Guidelines Flashcards
Definition of FRC
volume of gas present in the lung at end expiration during tidal breathing
Definition of Expiratory Reserve Volume
volume of gas maximally exhaled from FRC
Definition of Inspiratory Capacity
Maximum amount of gas that can be inspired from FRC
Definition of Inspiratory Reserve Volume
Volume of gas maximally inhaled from end-inspiratory level during tidal breathing
Definition of Residual Volume
Volume of gas remaining in the lung after maximal exhalation
Definition of Tidal Volume
volume of gas inhaled or exhaled during the respiratory cycle
Definition of Total Lung Capacity
volume of gas in the lungs after maximal inspiration (of the sum of all volume compartments)
Definition of Vital Capacity
volume change between full inspiration and complete exhalation
What is the preferred time to measure ERV?
Immediately after acquisition of FRC followed by slow IVC
What are 4 ways you get measure FRC?
- Body Plethysmography
- Gas washout
- Gas dilution
- Radiography
Key points of Plethysmography (ie. what does it measure)
- Includes ventilated and non-ventilated regions of the lung - thus HIGHER than dilution/washout methods
- May also be increased by gas in other areas of the body (ie abdo)
Key points of gas dilution/washout methods
- Tend to underestimate the true FRC
2. Simple and inexpensive to do
How does Plethysmography work?
- Measures volume of intrathoracic gas measured when airflow occlusion happens at FRC
- Minimal difference compared to washout/dilution in healthy people
- Plethys results HIGHER in those with lung disease and gas trapping
- Based on Boyle’s law: P1V1 = P2V2
Measurement technique of Body Plethysmography
- Turn on and calibrate machine
- Patient to close mouth over mouthpiece with neutral neck position
- Close door and allow to equilibrate
- Patient to breathe quietly until stable and expiratory level is met
- Shutter closes at/near FRC
- Patient pants for 2-3 seconds (freq of 0.5-1 Hz). If can’t pant, can do rapid inspiratory maneuvers against closed shutter
Repeatability criteria for Plethysmography
If 3 FRC results are within 5%
Calculation of Delta V in Plethysmography
Box: P1V1 = P2 (V1-delta V)
Lung: P3 FRC = P4 (FRC + Delta V)
Key points for Nitrogen washout
- Based on washing out nitrogen from lungs while patient breathes 100% O2
Measurement technique for Nitrogen washout
- Turn on machine and calibrate
- Patient sits comfortably and breathes for 30-60 seconds to assure stable end-tidal expiratory level
- Patient breathes 100% oxygen
- Exhaled nitrogen is measures
- Considered complete if Nitrogen concentration <1.5% for at least 3 breaths
- Need to wait at least 15 min between attempts
Equation for FRC N2
FRC N2 = (N2 washed out -N2 from tissue)/ (FN21 - FN22)
FN21 = fraction of nitrogen before the washout
FN22 = fraction of nitrogen after the washout
(volume = area under the curve of a N2 fraction % vs volume graph)
Key point of measuring FRC using helium dilution
Based on equilibration of gas in lungs with known volume containing helium
C1V1 = (C1 + FRC) V2
Measurement technique for Helium Dilution
- Breathe for 30-60 seconds to ensure stable end tidal expiratory level
- Patient connected to test gas at end of normal tidal exhalation
- Continues to breathe regular tidal breaths
- O2 is increased to compensate for O2 consumption
- Helium concentration checked q15 seconds
- Test complete when change in concentration = <0.02% for 30 seconds
What is an important value for derivation of the references values
Height = most important factor
** Lung growth typically falls behind growth spurt in adolescents
Definition of FVC
Maximal volume of air exhaled with maximally forced effort from a max inspiration
Definition of FEV1
Maximal volume of air exhaled in the first second of a forced exhalation from a position of full inspiration
What is useful about the flow-volume loop?
Useful for assessing magnitude of effort
- *Should show 1 sec before start to allow for calculation of the back extrapolated volume
- Last 2 seconds should be displayed to show end of test criteria
Definition of Calibration
finding the relationship between the measured values of flow and the actual values of flow
** should be within 3%
3 phases of spirometry
1) Maximal Inspiration
2) Blast of Exhalation
3) Continued Complete Exhalation
Procedure for recording FVC
1) check calibration
2) Explain and prepare patient and get H & W
3) Correct position, noseclip and mouthpiece in mouth with lips closed around
4) For closed and open circuit = inhale completely and rapidly to TLC with <1 s pause, Exhale completely until no more air can be expelled while sitting upright, repeat for 3-8 maneuvers
If there is a delay between TLC and forced expiration, what would that affect?
Delay shown to cause reduction in PEF and FEV1
What is the Back Extrapolated Volume?
- creates a new “time zero”
- found by tracing back from the steepest part (largest slope) of the curve (volume/time) over an 80ms time period
- to be accurate: extrapolated value must be <150mls or <5% of FVC
2 recommended End of Test criteria
- Patient cannot or should not continue further exhalation
- Volume/time curve shows no change in volume (<0.025L) for >1 sec in someone who has exhaled long enough: <10 = >3 seconds, >10 = >6 seconds
*If test does not meet EoT criteria, it should not count towards one of the 3 acceptable maneuvers
7 factors for Acceptable curves
- Good start (extrapolated volume <5% of FVC or <150 mls)
- No cough during first second, or other times that affects accuracy of results
- No early termination (good end of test)
- No Valsalva/glottic closure/hesitation (reduced FEV1 +/- FVC)
- No mouthpiece leak
- No obstructed mouthpiece
- No extra breath during maneuver
3 Between maneuver criteria
- Need 3 acceptable curves
- Repeatability = FVC and FEV1 is <0.15L between largest and next (<0.1L if FVC <1L)
- Try not to exceed 8 blows
Test result selection
- Select largest FVC and FEV1 from acceptable curves
- May also obtain slow VC or IVC (IC tends to be larger than FVC)
Maneuver for doing Maximal Expiratory Flow-Volume Loops
Take rapid full inspiration to TLC from mouth - insert mouthpiece - then maximal expiration followed by maximal inspiration
OR
Insert mouthpiece during tidal breathing - at FRC make slow expiration to RV - slow inspiration to TLC- maximal expiration to RV - rapid inspiration back to TLC
When should patients not take meds before spirometry?
If aim of the study is to document reversible airflow limitation - should do test before regular drugs
(SABA > 4 hours, LABA > 12 hours, no smoking <1hr)
*If aim of study = determine whether lung function can be improved with therapy in addition to current therapy - subject can continue with regular meds
Method for documenting reversibility in spirometry
- After 3 pre-BD loops, give SABA (ventolin) via spacer (dose = 400ug) or ipratropium (4x40ug)
- wait 10-15 min for SABA or 30 min for anticholinergic
- Improved deposition with CFC free MDIs (smaller particle size)
When during the test should you measure Slow VC?
Should be done prior to FVC (due to potential for fatigue and history effects - repeated measurements may increase FRC due to gas trapping in those with severe airflow obstruction)
Can do either IVC or EVC maneuver
Maneuver for Peak Expiratory Flow
Flow achieved from maximal forced expiratory maneuver
Procedure must be rapid - deliver blow without delay
Repeat x 3 - need to be within 0.67L/s to be repeatable
Maneuver for Maximum Voluntary Ventilation
Maximum volume of air a subject can breathe over a specified time (12 sec for normal subjects)
- 3 resting tidal breaths
- breathing at a rate of 90-110/min
- maximal effort (as deep and rapid as possible)
- Sum of all individual exhalations calculated, multipled by correction factor during the best 12 seconds
- minimum of 2 attempts (should be within 20% of each other)
Goal = VT of 50% of VC with RR ~90/min
Definition of Accuracy
The closeness of agreement between the result of a measurement and the true value
Definition of Repeatability
Closeness of agreement between results of successive measurements with the same conditions
Definition of Reproducibility
Similar to repeatability, however the conditions are changed
Patient considerations for lung function testing
- Not within 1 month of MI
- chest/abdo pain, oral/facial pain exacerbated by mouthpiece, stress incontinence, dementia, confusion
What measurement can you use as a surrogate for height?
Armspan (tips of middle fingers)
Things to avoid before PFT
- Smoking within 1 hour
- Alcohol within 4 hours
- Vigourous exercise within 30 min
- clothing that restricts full chest and abdominal expansion
- large meals withn 2 hours
- SABA use within 4 hours
Ways to prevent infection in the PFT lab
- Hand washing, barrier devices
- wear gloves when handling potentially contaminated equipment
- wash hand between patients
- disinfect/sterilize reusable mouthpieces, tubes, valves and manifolds
- equipment that comes in contact with mucosal surfaces should be sterilized, disinfected or discarded
- closed circuit equipment should be flushed with room air 5 times
- open circuit - only the portion of the circuit where re-breathing occurred should be decontaminated
- Decontaminate equipment esp with hemotypsis or oral lesions
- TB: ventilation, air filtration, UV decontamination
What do the references values mean for PFTs?
Comparison to healthy subjects of same anthropometric characteristics and ethnicity
- important to measure height and weight for each person
- adjust for race if possible
Definition of air flow obstruction on PFT
Reduction in FEV1/FVC below 5th percentile of predicted value
*Earliest change = slowing in the terminal portion of the spirogram
Causes of reduced FVC and FEV1 in airflow obstruction
- patients who fail in inhale or exhale completely
- if flow is so slow that they can’t exhale to RV
- lower airway collapse causing gas trapping (RV may be elevated)
Definition of air flow restriction on PFT
Reduction in TLC below the 5th percentile of predicted value and a normal FEV1/VC
*Suspect with reduced VC, increased FEV1/FVC ratio or convex curve
Other causes for high ratio and reduced VC apart from restriction
- submaximal effort
- patchy peripheral airflow obstruction
Does a reduced VC alone qualify for air flow restriction?
No - Need to have reduced TLC as well
** Special = Pneumothorax and non-communicating bullae: normal ratio and normal TLC (on plethys), low FEV1 and low VC, (low TLC if gas dilution)
Definition of Mixed Abnormality on PFT
Presence of obstruction and restriction
*Present when low FEV1/VC AND low TLC
Which measure do you look at for severity classification for airflow obstruction?
FEV1
Mild >70 Moderate 60-69 Moderate-severe 50-59 Severe 35-49 Very severe <35
Why do FRC, RV, TLC and RV/TLC increase with severe obstruction?
Reduced lung elastic recoil
What is considered a meaningful bronchodilator response?
12-15% change from baseline in FEV1 +/- FVC (changes <8% are likely to be within measurement variability)
ATS: change in 12% AND 200ml difference (>12 yrs) from baseline
What variable seems most affected by upper airway obstruction on spirometry?
PEF (can be reduced)
Examples of variable extrathoracic airflow obstruction
Repeatable plateau of inspiratory flow (decreased because the pressure surrounding the airways cannot oppose the negative pressure generated by inspiratory effort)
Ex: VCD
Examples of variable intrathoracic airflow obstruction
Repeatable plateau of forced expiratory and normal forced inspiratory loop
Ex: Tracheomalacia
Examples of fixed airflow obstruction
Repeatable plateau during both expiratory and inspiratory loops
Ex: Subglottic stenosis
What does a sawtooth pattern on inspiratory or expiratory phases mean?
May represent mechanical instability of airway wall
What do you see on spirometry with unilateral mainstem bronchi obstruction?
Maximum inspiratory flow tends to be higher at the beginning than the end, because of a delay in gas filling
What is considered a significant changes in lung function over time?
If FVC or FEV1 change by more than 11-12% in 1 week - likely clinically significant
(>15% in one year = significant)
What is the lower limit of normal for DLCO?
Lower 5th percentile of reference population
Mild >60% but
What can cause isolated reduced DLCO?
Anemia Pulmonary Vascular Disorders ILD Emphysema PH
Causes of normal DLCO in the context of restrictive lung disease
Chest wall or neuromuscular condition
Causes of reduced DLCO in the context of restrictive lung disease
ILD
Sarcoidosis
Pulmonary fibrosis
Causes of reduced DLCO in the context of obstructive lung disease
Emphysema
Lymphangioleiomyomatosis
What can cause an elevated DLCO?
Asthma
Obesity
Intrapulmonary hemorrhage
What does a high DLCO/VA suggest?
Extrapulmonary abnormality (pneumonectomy or chest wall restriction)
What does a low DLCO/VA suggest?
Parenchymal abnormality
Steps in doing a single-breath CO test
- Tidal breathing after nose clips on and patient on mouthpiece
- Exhalation to RV (if severe obstruction, must be <12 seconds)
- At RV, patient connected to test gas and patient inhales to TLC (inspiratory volume should be at least 90% of VC)
- test gas: 0.3% CO, 21% O2, tracer + nitrogen
- tracer should be insoluble, chemically, and biologically inert
- DLCO calculated using alveolar volume, breath hold time, barometric pressure, frac concentration of CO and tracer gas in inspired and exhaled gas
How is dead space measured in the single breath CO test?
Fowler method (the volume at which the shaded area above the tracer gas on the gas washout vs exhaled volume curve = the shaded area below the curve)
How can you measure TLC from the single breath CO test?
Calculated by adding the expired volume to the end expiratory volume and subtracting dead space
What are the acceptability criteria for DLCO testing?
- Adequate inspiratory volume (>90% of the largest VC)
- Inhalation of > 85% of the test gas in 4 seconds
- Stable breath hold for 10 seconds with no leak
- Sample collection within 4 seconds of exhalation
What are the repeatability criteria for DLCO testing?
- 2 acceptable maneuvers within 2ml/min/mmHg
- should do at least 2 maneuvers and average results
What adjustments are made to predicted value of DLCO prior to interpretation?
1) Hemoglobin
2) Carboxyhemoglobin and CO back pressure (COHb can affect binding sites and CO also reduces the driving pressure for CO transport from alveoli to capillary)
* 2% decrease in DLCO for each 1% increase in COHb
3) Barometric Pressure: as BP decreases, the PiO2 decreases and DLCO increases (0.53% increase in DLCO for every 100m in increase in altitude)
3 Lung function test options for Sedated Infants
1) Raised-volume rapid thoracoabdominal compression (RVRTC) technique
2) Infant Pleth
3) Multiple breath washout = LCI
5 Lung function test options for Preschoolers
1) Spirometry
2) Pleth (specific airway resistance = sRaw)
3) Interrupter resistance technique (= Rint)
4) Forced oscillation technique (FOT)
5) Multiple breath washout = LCI
Equation for lung clearance index
Cumulative expired volume/FRC
Volume when concentration falls below 1/40th of original
Which lung disease as infant RVRTC been shown to be helpful in predicting early disease?
CF
What is the most accurate method for detecting early lung disease in preschoolers?
LCI
(LCI > sRaw > spirometry)
*recommendation - 25% decrease in sRaw as cut-off for asthma in young children
What are the 3 major roles for any lung function test?
1) Monitor disease severity over time
2) Evaluate response to treatment
3) Serve as objective outcome measures in clinical research studies
What are developmental differences in preschoolers vs older children regarding their ability
1) FEV1/FVC ratio is 90-95% in 5-6 year olds and even higher in young children
2) Utility in FEV1 in older children is due to its location on the effort-independent part of the curve
3) Unlikely that preschool children will not have the respiratory muscle strength to maintain flow limitation to lung volumes as low as 85-90%
What is the most useful lung function test for preschoolers with CF?
Lung Clearance Index
Spirometry recommendations for preschoolers (13)
1) Live flow-volume curves
2) Review FVC, FEV1, VBE, point when flow ceases as proportion of PEF
3) Acclimatize child to equipment and lab
4) Flow and Volume-driven incentives may be useful
5) Posture and nose-clip use should be recorded
6) Make sure no leak
7) Minimum 3 maneuvers, no max
8) Inspect curves for rapid rise to peak flow and smooth descent without cough or glottic closure
9) if VBE > 80mls or 12.5% FEV1 - inspect curve but dont always reject
10) Premature termination = cessation of flow at >10% FVC (may use FEV1 but not FVC or ratios)
11) Report highest FEV1 and FVC
12) starting point for FEV1 determined from back extrapolation
13) At least 2 acceptable curves with FEV1 and FVC within 0.1L or 10% of highest value
2 ways to measure tidal volume?
- Tidal expiratory flow analysis
2. Thoraco-abdominal motion analysis
Maneuver for tidal expiratory flow analysis?
- Stable breathing in seated/standing position
- At least 30 seconds /10 tidal breaths
- Report mean, SD, coefficient of variability
- inspect Flow volume curve for repeatability and flow-time to ensure steady tidal breathing
*Flow at the airway determined by driving pressure and resistance (F = P/R)
P determined by elastic recoil of the respiratory system and net pressure due to respiratory muscle activity
*Those with wheezing with have increased Time to Peak tidal expiratory flow/total expiratory time AND increased Volume at peak tidal expiratory flow/expired tidal volume (both decrease with ventolin)
Maneuvers involved in Thoraco-Abdominal Motion Analysis
With increasing negative intrathoracic pressure, rib cage lags behind abdomen and may even more inwards initially
- Measure with child seated, with mouthpiece
- Occlusion with valve closing in <10ms and for <100 ms
- Occlusion triggered by PEF in expiration
- Record 10 occlusions to get 5 acceptable maneuvers
- Report median
*During sudden occlusion, alveolar P will rapidly equilibrate with P at the mouth (Pmo)
Rint = Pmo/flow
Principles of Forced Oscillation Technique
External pressure wave applied at the mouth
Resulting pressure-flow pattern is analyzed in terms of respiratory impedance
Procedure for Forced Oscillation Technique
- System should be able to measure a reference impedance of >1.5 kPa.s/L within 10% of <0.1L
- Excitation frequency = 4-8 Hz
- Child is seated, breathing through mouthpiece with noseclips
- Acquisition over several breathing cycles, typically 8-16
- 3-5 measurements
- Mean reported as well as SD and CV
Point of doing Multiple Breath Washout Test
Assesses ventilation distribution and FRC
Procedure for Multiple Breath Washout Test
- child seated upright with mouthpiece or sealed facemark
- Deadspace = <1-2ml/kg
- Sufficiently long wash-in to allow gas to equilibrate in lung - usually 10s after inspired/expired concentrations are equal
- Washout continues until end-tidal concentration = 1/40th starting concentration, over 3 breaths
- Watch Vt and gas concentration to detect for any leaks
- FRC and indices of ventilation inhomogeneity should be calculated on each washout. Mean values, with different <10% from 2 washouts can be reported
- LCI = cumulative expired volume, minus dead space times number of breaths divided by FRC
Procedure for Bronchial Responsiveness Tests in Preschoolers
- Perform in children who are free from respiratory infection (>3 weeks), normal auscultation and PFTs including sat > 95%
- Agent should be delivered by tidal breathing (standard nebulizer output for 2 min) or dosimeter method (deep inhalation, nebulization 0.6 seconds, repeated every 5 min)
- if transcut pp O2 used - change >20%
- Avoid SpO2 as a sole marker of bronchoconstriction
- An increase in resistance of up to 35-40% = negative test
- Test should be ended with bronchodilator and confirmation that PFT is at baseline
For DMD, what is the best negative predictor of survival?
FVC <1L
What is considered to be ineffective airway clearance?
Peak cough flow <160L/min
MEP <45 cm H20
According to ATS, what values would benefit from assisted cough techniques?
Peak cough flow <270L/s
MEP <60 cm H20
*CDC: FVC <40%
BTS: peak cough flow <270 L/s
When should you offer nocturnal NIV to DMD patients?
Awake PaCO2 >45
O2 sat <92-95%
FVC <30-40%
When should you consider daytime NIV to DMD patients?
Daytime PaCO2 >50 or O2 sat <92%
What is the worry about providing oxygen to DMD patients?
Can mask underlying cause and they may lose their hypoxic drive to breathe
At what FVC is the prognosis for recovery from scoliosis surgery best?
FVC >40%
What should the extubation protocol for DMD kids include?
Airway clearance techniques
Immediate use of NIV following extubation
Indications for tracheostomy in DMD?
patient and family preference
cannot tolerate NIV
medical infrastructure can’t support NIV
3 failures to achieve extubation despite NIV and cough assist
Failure of cough assist to prevent aspiration of secretions
Gene for CCHS
Phox2B
“Paired like homeobox”
Inheritance pattern for CCHS
Autosomal dominant
Mosaicism in 5-10%
De novo mutations (most = de novo unless parents are affected)
Clinical picture of CCHS
Reduced tidal volumes, monotonous respiratory rates awake and asleep
More profound hypoventilation occurs with sleep
Often become hypoxic and hypercarbic
Lack responsiveness to the physiologic changes and often do not arouse
Lack perception of asphyxia during wakefulness (and exertion)
Aspects of autonomic dysregulation in CCHS
Hirschsprungs Neural crest tumours Reduced pupillary light response Esophageal dysmotility Breath holding spells Reduced basal temperature Sporadic profuse sweating Lack of perception to dyspnea Altered response to exercise challenge and environmental stressors
Mutations on PHOX2B that play a role in CCHS
Two polyalanine repeat regions in exon 3 - SECOND one is important!
Normal = 20 alanines
either PARM or NPARM mutations (NPARM worse)
Affected individuals have more polyalanines in this sequence (24-33)
**Most common = 20/25, 20/26, 20/27
How many patients have NPARM mutations in CCHS?
10%
Are PARM or NPARM mutations worse in CCHS?
NPARM
- Includes sequence changes outside of the polyalanine repeat and can cause frameshift variants
- Typically more severe phenotypes
Phenotypes with increased risk if you have NPARM mutation in CCHS
Continuous ventilatory support
Hirschsprungs
Neural crest tumours
Phenotypes with increased risk if you have PARM mutation in CCHS
Neural crest tumours (20/29-20/33)
Autonomic nervous system dysregulation
What is the theory behind later onset CCHS?
likely a reflection of variable penetrance of the 20/24 and 20/25 mutations or NPARM with environmental cofactor
Evaluation for CCHS
- H&P (including response to sedation/anesthesia and delayed recovery, unexplained seizures and neurocognitive impairment)
- Review photographs for facial dysmorphology
- 72 hour holter for investigation of prolonged sinus pauses
- PSG for ventilation impairment
- Hematocrit and reticulocyte count (polycythemia and response to hypoxemia)
- Bicarb level
- CXR, echo, or ECG (pulmonary HTN)
- Barium enema or manometry in cases of constipation
What disease is important to distinguish from CCHS?
ROHHAD-NET
Presents with rapid obesity, hypothalamic disorders, OSA, hypoventilation, autonomic dysregulation
Recurrence rates for CCHS
50% of transmitting it if affected parents
50% chance of recurrence with unaffected mosaic parents
Mechanism of PARM in CCHS
regarded as flexible spacer elements essential to conformation, protein-protein interaction and DNA binding
Mechanism of PHOX2B mutations in CCHS
Typically responsible for expression regulation of genes involved in the development of the ANS
Diagnosis and clinical course for CCHS
1) Need to send for PHOX2B screening test for diagnosis. Rule out other causes of hypoventilation + other lung disease muscle weakness, cardiac disease
2. Investigations for Hirschsprungs
3. Serial chest and abdo imaging essential for PARM and NPARM with 20/29-20/33
4. Annual 72 hour holter for abhorrent cardiac rhythms
5. Annual echo, hematocrit, reticulocyte count (at risk for PH)
6. Ophthalmologic evaluation
7. Reported to have decreased school performance - neurocognitive test annually
8. Biannual then annual comprehensive physiologic studies to assess ventilatory needs
What is the hallmark of CCHS?
Alveolar hypoventilation
- *Diminished tidal volume and minute ventilation is most easily seen in non-REM sleep but also abnormal in REM and wakefulness
- *Need for ventilatory support tied to PARM mutations (worse with more PARM >20/27) and NPARMs
Options for ventilatory management in CCHS
Trach
BiPAP
Negative pressure ventilators
Diaphragmatic pacing
Problem with diaphragmatic pacing?
Will be picked up in ECG so may artificially elevate HR and hide the sinus pauses
Should kids with CCHS swim?
NO!
Prohibited from underwater swimming as they won’t perceive asphyxia that occurs with drowning and breath holding
Is NIV optimal management in CCHS?
No
*Considered after 6-8 years
What form of ventilation is recommended for CCHS especially in the first few years?
Trach
**Portable postive pressure ventilator via trach = most common method of providing home ventilation
**Must have power generator and placement on emerge list for local power company and fire dept
4 signs that a trach needs upsizing
- Difficulty achieving adequate gas exchange and plateau on ETCO2
- Increasing ventilator settings to those above other similar aged children
- More frequent pneumonia
- Audible leak
*Bronch q12-24 months for assessment
Recommendation for BiPAP in CCHS
Can be used via nasal mask, prongs or facemark (but discouraged)
Provide continuous flow with fixed leak
Can adjust pressure accordingly
Should not be used outside of sleep - interferes with activity, skin breakdown, mid face hypoplasia
Recommendation for Negative Pressure Ventilation in CCHS
- Many children still need a trach
- Not portable
- Requires supine position
- Causes skin irritation and a “chilled” sensation
- Possible when older (6-8)
Mechanism for Diaphragmatic Pacing in CCHS
- Generates respiratory rate using the diaphragm
- Uses battery operated external transmitter sent via antenna with a radio signal sent to subcutaneous bilateral receiver - generates an electrical impulse which stimulates a breath
**Can give 12-15 hours of support
If needing 24 hours - need a second method of ventilation for part of the day
MUST have backup support
OSA may be a complication *dyssynchrony with the upper airway muscles
Optimal CCHS candidates for Diaphragmatic pacing
No or mild lung disease
Not obese
Intact phrenic nerve/diaphragm integrity
Needs tracheostomy initially
Lifestyle recommendations for CCHS
No alcohol or drug use
Be careful with pregnancy - increases respiratory load, decreases minute ventilation and central drive
Low mortality for those managed aggressively
Most children have prolonged survival with good quality of life
2 techniques for Multiple Breath Washout
1) Nitrogen
2) SF6
Explain how nitrogen washout works
1) RA in (nitrogen ~80%)
2) Washout: 100% O2
Done with N2 < 1.5% x 3 breaths
Cheapest and most commonly used
No wash-in needed
Intert but “intrinsic” gas - lungs excrete nitrogen
Explain how SF6 washout works
1) Wash-in: SF6 with 21% O2 - to 4%
2) Washout: RA (open circuit)
“Extrinsic”, not produced by the lungs
Easier detection
Disadvantages: greenhouse gas, expensive, longer wash-in period
Equation for Lung Clearance Index
(Cumulation expired volume to reach 1/40th gas)/FRC
What does LCI measure?
Measures ventilation homogeneity
Higher LCI = more lung inhomogeneity
Healthy = ~7 (5.7-7.7), age-dependent
Decreases in 1st 2 years of life - plateaus (toddler) - then increases
Can be normal in atelectasis/complete obstruction
Main application = CF
What are the 3 2019 End of Forced Expiration criteria for spirometry? (Need 1 of these)
- Expiratory plateau ≤ 0.025L/s in the last second
- Expiratory time > 15 seconds
- FVC within repeatability tolerance
> 6yr: ≤ 0.150L between 2 highest values for FVC and FEV1
<6yr: ≤ 0.100L or 10%
Activities to avoid before lung function testing
- Smoking +/- vaping +/- water per use within 1 hr
- Consuming intoxicants within 8 hr before testing
- Performing vigorous exercise within 1 hour before testing
- Wearing clothing that substantially restricts full chest and abdominal expansion
According to Canadian TB guidelines, who are the most affected populations in Canada for TB?
Canadian-born aboriginals
Foreign-born individuals
Disproportionate number of incident cases in North
Most common TB disease site
Pulmonary 64%
Peripheral lymph nose second most common 13%
Almost all cases culture confirmed (80%)
What is the most common co-infection with TB?
HIV
Characteristics relating to pathogenesis of M. tuberculosis
Almost exclusively a human pathogen
Airborne transmission
Distribution of inhaled droplet nuclei into the lung determined by pattern of regional ventilation - follows the most direct path to the periphery and favours middle and lower zones (which receive the most ventilation)
If successfully cleared by host macrophages - IGRA and TST = negative
At which time post infection would we expect the TST and IGRA to be positive?
After 3-8 weeks - the host develops specific cell-mediated immunity and delayed-type hypersensitivity
Infection and immune conversion almost always asymptomatic
Once infected, what is the progression of TB?
Granuloma formation - as more cellular infiltrates continue to the site of infection = centre becomes caseous or necrotizing
Ghon focus = calcified granuloma
Ghon complex = calcified granulomatous focus in a draining lymph node
Other early manifestations of TB
Erythema nodosum - cutaneous immunology reaction to an extra cutaneous TB infection
Phlyctebular conjunctivitis - hypersensitivity reaction
Early disease progression in TB
Progression to disease = recently infected individuals unable to contain infection despite immune response and end up progressing to TB in months
4-12 mos = early disease manifestations include:
- Complicated LN disease
- Immunocompetent - intrathoracic adenopathy and unilateral pleural effusion
Definition of late TB disease
Any individual with a dx of TB made within 18-24 most of infectious = primary disease
Almost always the result of lymphs-hematogenous spread
Definition of Latent TB infection
Positive TST or IGRA in the absence of active disease
Organisms can shift into state of dormancy if allowed to settle through gradual reductions in oxygen tension
Defnition of re-infection of TB
Takes up to 18 mos from initial infection for cell-mediated immunity to occur - reinfection during this time = same disease risk as initial infection
Is reactivation or reinfection more common in Canada?
Reactivation
Risk factors for progression from TB infection to disease
- Children < 5 yrs (especially infants), young adults (especially females) and older adults (especially male)
- Undernutrition
- Seasonality (highest incidence in spring and summer)
Progression depends on immunocompetence of the host
Characteristics of transmission of TB
- Aerosol route
- Humans = reservoir
- Droplet nuclei created by forced expiratory efforts and have an extremely slow settling rate
- Rate of transmission can be measured by the percentage of close contacts whose TST and IGRA responses are converted
- Transmission requires a TB patient to be able to produce airborne infectious droplets
- Smear positive/culture postive TB more infectious than smear negative/culture positive
- Cavitary disease more infections than non-cavitary disease
- Laryngeal disease more infectious
- Sneezing = most infectious (then coughing followed by breathing)
Environmental factors relating to TB transmission
- Air circulation and ventilation
- Proximity to the source case
- Duration of exposure
Areas that are included in the diagnosis of Respiratory TB
- Primary TB
- Pulmonary TB
- Tuberculous pleurisy
- TB of the intrathoracic nodes, mediastinum, nasopharynx, nose and sinus
Classic symptoms of TB
- cough at least 2-3 weeks duration
- Dry -> productive
- Fever and night sweats
- Hemoptysis, anorexia, weight loss, chest pain (manifestations of advanced disease)
Most common finding on exam for TB
Normal exam
Signs of extra pulmonary TB
LAN, pleural effusion, abdominal and bone or joint involvement
Algorithm for active TB testing
- CXR - 2 views
- Microbiology
- Evaluation for drug resistance
Components of microbiological testing for TB
- Sputum: smear yield reduces with each collection, but culture yield can increase, sputum should be induced
- Bronchoscopy: might consider if unable to perform sputum induction or if all samples are smear negative
- Gastric aspirate: in those who cant expertorate
- Smear-microscopy: Ziehl-Neelson (light micro), Auromine stain (fluorescence) - high specificity for mycobacteria
- Mycobacterial culture = gold standard (Lowenstein Jensen media)
- Nucleic acid amplification test - sensitive, PCR most common
2 methods for testing for drug resistance in TB
- Phenotypic (gold standard)
2. Molecular methods
Situations in which neither TST nor IGRA should be used for testing
- People who have a low risk of infection and a low risk that there will be progression to active TB disease if they are infected
- For the diagnosis of active TB
- For routine or mass screening for LTBI of all immigrants
- For monitoring anti-TB treatment responses
Situations in which IGRAs are preferred for testing but a TST is acceptable
- People who have received BCG vaccine after infancy (1 year of age) and/or have received BCG vaccination more than once
- People from groups that historically have poor rates of return for TST reading.
Situations in which TST is recommended for testing but an IGRA is NOT acceptable
It is planned to repeat the test later to assess risk of new infection (i.e. conversions), such as repeat testing in a contact investigation or serial testing of health care or other populations (e.g. corrections staff or prison inmates) with potential for ongoing exposure.
Situations in which both tests can be used (sequentially, in any order) to enhance sensitivity
- When the risks of infection, of progression to disease and of a poor outcome, are high.
- In children (under age 18 years) with suspected TB disease, IGRAs may be used as a supplementary diagnostic aid in combination with the TST and other investigations to help support a diagnosis of TB.
- Repeating an IGRA or performing a TST might be useful when the initial IGRA result is indeterminate, borderline or invalid, and a reason for testing persists.
Steps for performing a TB skin test
○ 5 TU of purified protein derivative is used (not 1-TU)
○ Refrigerated at 2-8 degrees celsius
○ 0.1 mL of solution
○ Try to limit light exposure
○ Use within one month of opening
○ Inject the inner aspect of the forearm, about 10 cm below the elbow
○ Do not use EMLA or other anesthetic cream
○ Use a ¼-½ inch 26 or 27 G needle
○ Insert at 5-15 degree angle so that needle is just visible below the surface of the skin
○ Slow intradermal injection
○ Site should not be bandaged and patient should be discouraged from scratching or touching the area
○ If the injection is too deep - it will not harm the patient, but the test will need to be repeated
○ Record : date of infection, dose of PPD, PPD manufacturer, lot number, expiration date, site of injection, person administering test
○ Reading should be performed 48-72 hours later
○ Induration should be palpated
Contraindications to TST
- Positive, severe blistering TST reactions in past, extensive burns or eczema present over TST testing sites
- Documented active TB or well-documented history of adequate treatment for TB infection or disease in the past
- Those with current major viral infections (measles, mumps, varicella)
- Live vaccine within the past 4 weeks (increases false negatives)
TST can be used in those taking low doses of systemic corticosteroid (<15 mg prednisone daily)
Potential causes of false-negative TST
- Improper storage of tuberculin material or contamination, improper dilution or denaturation
- injection of too little or injection too deeply
- Administration > 20 min after drawing it up
- Inexperience reader/technical issues
- Active TB (especially if advanced)
- Other bacterial infections (typhoid fever, brucellosis, typhus, leprosy, pertussis)
- HIV infection (especially if CD4 count <200)
- Other viral infection (measles, mumps, varicella)
- Fungal infection
- Live virus vaccination (MMR)
- Immunosuppressive drugs and steroids
- Metabolic disease (chronic renal failure, severe malnutrition, stress)
- Disease of lymphoid organs (lymphoma, CLL, sarcoidosis)
- Age: infants <6 mos, the elderly
Management of a positive TST result
STEP 1 - deciding that a TST is positive
- Based on size and using criteria
STEP 2 - medical evaluation
- Assess for symptoms suggestive of possible active TB, risk factors for TB, Chest X ray
- In the presence of symptoms or abnormal CXR, microscopy and culture should be performed
- If no evidence of active infection, then recommendations for treatment of LTBI be made
Interpretation of a positive TST
- Size of induration
- Positive predictive value
- Risk of disease if person is truly infected
People considered to have a positive TST with 0-4mm
- Child under 5
- High risk of TB infection
People considered to have a positive TST ≥ 5mm
- HIV infection
- Contact with infectious TB case within the past 2 years
- Presence of fibronodular disease on CXR
- Organ transplantation
- TNF alpha inhibitors
- Other immunosuppressive drugs
- End-stage renal disease
People considered to have a positive TST ≥10mm
All others including:
- TST conversion (within 2 years)
- Diabetes, malnutrition, smoking, alcohol
- Silicosis
- Hematologic malignanies
Typical CXR findings for TB
Infiltrates in apical-posterior segments of upper lobes or superior segments of the lower lobes
Volume loss
Cavitation
Signs of complications:
- Small nodular shadows from airway involvement
- Pleural effusion
- Pneumothorax
BCG vaccination can be ignored as a cause of a positive TST under which circumstances?
- BCG vaccination was given in infancy, and the person tested is now aged 10 years or older
- High probability of TB infection: close contacts of an infectious TB case, Aboriginal Canadians from a high-risk community or immigrants/visitors from a country with high TB incidence
- High risk of progression from TB infection to disease
BCG should be considered the likely cause of a positive TST under which circumstances
- BCG vaccine was given after 12 months of age AND
- There has been no known exposure to active TB disease or other risk factors AND
- the person is either Canadian-born non-Aboriginal OR
- an immigrant/visitor from a country with low TB incidence.
Definition of TST conversion
- TST of 10 mm or greater when earlier test < 5 mm induration
- If earlier test 5-9 mm induration:
- Increase of 6 mm or more - suggested for those who are immunocompromised with increased risk of disease or for an outbreak - Increase of 10 mm or more - all others
TST conversion occurs within 8 weeks of exposure
What is the booster effect that can be seen with 2-step TST?
- Single TST may stimulate an anamnestic immune response so that a second TST performed later on will elicit a greater response
- This can be confused with conversion
- Should be performed if likely to perform serial testing
- If second TST 10 mm or more, patient should be referred for medical evaluation
Types of IGRAs
IGRA = Interferon Gamma Release Assays
- Quantiferon TB Gold in tube (QTF-GIT)
- T spot.TB
Specificity >95% for the diagnosis of LTBI, not affected by BCG vaccine
Most NTM not picked up by IGRAs, except Mycobacterium kansasii and Mycobacterium marinum
Sensitivity diminished by HIV infection → indeterminate result
Are IGRAs recommended for active TB diagnosis or for serial testing purposes?
No
What are the 2 phases of TB treatment?
- Initial Intensive: 2 months, daily meds
2. Continuation: 2 drugs given, length variable, daily or intermittent therapy
Which TB drug requires the addition of Pyridoxine?
Isoniazid
For: patients with diabetes, renal failure, malnutrition, substance abuse, seizure disorders or for women who are pregnant or breastfeeding
Typical duration of the Continuation phase in TB treatment
4 months (7 months for elderly, hepatotoxicity, pregnant)
When would you consider prolonging the continuation phase?
- More extensive disease
- Cavities on chest x ray in the first 2 months of therapy
- Being culture positive after 2 months of therapy
- Having a cavity of CXR at the end of treatment
- HIV patients not on ARV therapy
Antibiotics for treatment of TB
Rifampin
Isoniazid
Pyrazinamide
Ethambutol
Criteria for intermittent therapy
- Should only be used with direct observed therapy (DOT)
- In the intensive phase, daily therapy is recommended - this can be given 5 days per week if therapy is given by DOT
- If DOT in the initial phase is difficult, patients may be treated with 3x weekly therapy if they are HIV-, have a low bacillary load and have demonstrated adherence to their DOT in the first 2 weeks
- In the continuation phase, if DOT is used then 3 x weekly therapy is preferred.
- Intermittent therapy not recommended for HIV infected patients
When to add adjunctive steroid for TB treatment
TB meningitis and TB pericarditis
Indications for hospitalization for TB
- Investigation and/or treatment of symptoms i.e. hemoptysis, malaise, cachexia
- Establishment of an acceptable therapeutic regimen in patients with drug related adverse events or with known/suspected resistance
- Drug desensitization
- Management of associated medical conditions complicating TB i.e. HIV infection
- Provision of airborne isolation if cannot be effectively provided as an outpatient
- Involuntary admission
Follow-up during active TB treatment
- Follow up during active TB treatment should be monthly to monitor response to therapy and adherence
- Patients who are AFB smear positive should have weekly smear examination until smear negative.
- Once smear negative, one culture should be done at the end of the second month of therapy to assess the risk of relapse, then again towards the end of therapy
- CXR should be performed at 2 and 6 months
Side effects of Isoniazid
Rash Hepatitis Neuropathy CNS toxicity Anemia
Side effects of Rifampin
Drug interactions Rash Hepatitis "flu-like illness" Neutropenia Thrombocytopenia
Side effects of Pyrazinamide
Hepatitis
Rash
Arthralgia
Gout
Side effects of Ethambutol
Eye toxicity
Rash
Baseline ophthalmological assessment should be obtained before starting EMB (especially in young children)
Treatment of suspected TB drug induced hepatotoxicity
- Stop PZA, INH and RMP and start at least 2 alterative TB meds
- Review history carefully, and check viral serologies (hep A, B, C)
- When transaminases have returned to normal, restart RMP (not likely to give hepatitis)
- Wait 2 weeks, then start INH. If severe hepatotoxicity, consider not rechallenging with INH
- If RMP and INH are restarted and transaminases remain normal, assume that the hepatitis is due to PZA. Do not rechallenge with PZA
High Risk factors for reactivation of active disease from LTBI
Strongest = AIDS, but note that HIV also increases the risk
- Transplant (related to immunosuppression)
- Silicosis
- Chronic renal failure requiring hemodialysis
- Carcinoma of head and neck
- Recent TB infection (≤ 2 years)
- Abnormal CXR (fibronodular disease)
Indications for treatment of LTBI
Recent infection and increased risk of reactivation
Is LTBI treatment recommended if immune compromised and TST is negative
No
Regimens for LTBI treatment
Standard regimen
- 9 months of INH (Self-administered) **Now 4 mos daily RMP
Alternative regimen
- Six months of daily, self administered INH - less effective
- Four months of daily, self administered of INH and RMP acceptable
- Three months of once weekly directly observed INH and RPT - High rates of hypersensitivity
Is Pregnancy and breastfeeding safe with LTBI treatment
Yes but supplement with Pyridoxine if using Isoniazid or Rifampin
Clinical presentation of non-respiratory TB
- TB lymphadenitis
- Urinary tract TB
- Genital TB
- Miliary TB
- Spinal/vertebral TB (Pott’s disease)
- Joint/arthritis
- GI TB
- Peritoneal TB
- TB meningitis
- Tuberculomas
- Ocular TB
- TB pericarditis
Definition of drug-resistant TB
Drug resistant TB if strain is resistant to one or more first-line drugs (INH, RMP, PYR, EMB)
Characteristics of paediatric TB
- TB diagnosis in young children is a sentinel event indicating recent transmission
- Diagnosis is difficult since signs, symptoms and radiographic appearance is nonspecific and disease is often paucibacillary
- Primary infection usually accompanied by occult, subclinical bacteremia that seeds distant sites including the apices of the lungs, lymph nodes, CNS and may rapidly lead to severe forms (especially in kids < 5 years)
- No confirmatory test for LTBI
- Cavitation is rare in childhood disease
- Gastric aspirates: overall diagnostic yield is 50%
- Pyridoxine recommended for all children on meat and milk deficient diets, breast fed infants, those with nutritional deficiencies, those with symptomatic HIV infection, adolescents who are pregnant or breastfeeding
Diagnosis of TB depends on triad of: Positive TST or IGRA (delineating exposure), either an abnormal CXR and/or physical examination, discovery of a link to a known or suspected case of infectious TB
Treatment modification and duration for pediatric TB
- Fully susceptible, intrathoracic TB, INH, rifampin and PZA should be used for 2 months, followed by 4 months of INH and RMP (ethambutol can be dropped if fully sensitive)
- Minimum duration of therapy is 6 months - should be longer in patients with cavities or positive sputum cultures after 2 months (9 months)
- If hilar adenopathy alone is present, treatment as for pulmonary disease should be given
- Evaluation at least monthly
- Dose adjustments with weight
- Chest X ray 2 months into disease - however don’t change treatment based on cxr if clinical improvement
- Follow patients at least one year post d/c of treatment
Management of contacts of paediatric TB
- All exposed children should have a symptom inquiry and TST
- Those < 5 years, and all close contact children should have a physical examination and CXR
- Children < 5 years with negative TST should have window prophylaxis of INH - can be discontinued if asymptomatic and TST negative at that time
- In the exposed child, if the initial TST >/= 5 mm , then full course of LTBI is recommended
Targeted paediatric testing for latent TB infection
- Contacts of known TB
- Children with suspected active disease
- Children with known risk factors for progression of infection to disease
- Children who have travelled or resided for 3 months or longer in an area with a high TB incidence
- Children who arrived in Canada from countries with high TB incidence
Recommended management of the newborn infant exposed to TB
- Clinical exam
- TST
- CXR
- Cultures including a lumbar puncture
- Abdominal ultrasound
- HUS can be considered
- Window prophylaxis x 6 months with IHN, when TST can be repeated
- Congenital TB: oral isoniazid (10–15 mg/kg/day), oral rifampin (10–20 mg/kg/day), oral pyrazinamide (20–40 mg/kg/day), and IM streptomycin (20–40 mg/kg/day) for 2 months; isoniazid and rifampin should then be continued for an additional 6 months.
Risk factors for spontaneous pneumothorax
Smoking (most important)
Underlying lung disease
Tall, thin body habitus
Physical exam finding with pneumothorax
Reduced or absent breath sounds
Reduced ipsilateral chest expansion and hyper-resonant percussion
Haemodynamic compromise or significant hypoxia is
unusual in primary pneumothorax
Is size of the pneumothorax important?
- Size less important than degree of clinical compromize
- Rim > 2 cm associated with large ptx (BTS, inter pleural distance)
- Size does not correlate well with clinical symptoms
Treatment options for pneumothorax
- Patients with lung dz tolerate pneumothorax less well
- Important to distinguish btw primary and secondary ptx
- Breathlessness indicates the need for active intervention
- Size of ptx indicates rate or resolution and is relative indication for intervention
Primary, asymptomatic and small - F/U 2-4 weeks
Primary, symptomatic, >2 cm: Needle aspirate if no success - chest tube
Secondary, small <1cm, asymptomatic: admit for oxygen, observe 24 hours
Secondary, large 1-2 cm: needle aspirate
Secondary large > 2cm: chest tube
Follow-Up and further management pneumothorax
- Conservative management if no symptoms - outpatient review
- Suction not routinely recommended - reserved for persistent air leak (Increase risk of reexpansion pulmonary edema)
- Referral to a respiratory specialist within 24 hours of admission
Management secondary spontaneous pneumothorax
- All patients with SSP should be admitted to hospital at least 24 hours and receive supplemental oxygen
- Most will require insertion of a chest tube (aspiration less likely to be successful)
- Early referral to chest physician
- Persistent air leak > 48h should be discussed with surgeon
- SSP persistent airleak, unsuitable candidate for surgery
- Medical pleurodesis
- Consideration for ambulatory management with Heimlich valve
Discharge and follow-up post pneumothorax
- Patients should be advised to return to hospital if increasing breathlessness
- CXR 2 weeks post observation or NA
- Follow up by a respiratory physician until full resolution of ptx
- Air travel should be avoided until full resolution (1 month since occurrence, or 1 week post resolution)
- Diving avoided for life unless bilateral pleurodesis
- Normal lung function and CT scan afterward
- Return to work and resume normal activities once symptoms resolve
- Sports involving contact or extreme exertion should be limited until full resolution
Definition of Spontaneous vs Secondary Pneumothorax
Spontaneous pneumothorax = absence of any identified extrinsic cause.
PSP occurs in the absence of clinically apparent underlying lung disease
SSP occurs as a complication of a pre-existing underlying lung disease such as COPD, cystic fibrosis, lung malignancy ( primary or metastatic) or necrotising pneumonia of various causes.
Definition of Recurrent Pneumothorax
A subsequent episode of pneumothorax occurring after either an ipsilateral or contralateral pneumothorax.
When would a tension pneumothorax occur?
Tension pneumothorax occurs when the intrapleural pressure becomes greater than the atmospheric pressure throughout all phases of respiration. It can be seen in ventilated patients or after trauma or cardiopulmonary resuscitation, but is extremely rare in PSP
Indications for definitive management of primary spontaneous pneumothorax (PSP)
Second episode of PSP Persisting air leak >3–5 days Haemopneumothorax Bilateral pneumothorax Professions at risk (aircraft personnel, divers)
What is Medical chemical pleurodesis and who gets it?
Chemical pleurodesis should be reserved for people who cannot tolerate surgery
Prevention of recurrent pneumothorax should be undertaken surgically
- Lower recurrence rates than for medical pleurodesis
Chemical sclerosing agents:
- Minocycline, doxycycline
- Tetracycline
- Talc
- Risk of recurrence 10-20%
When to refer to surgery for management of pneumothorax
Persistent air leak - referral to surgeons at 3-5 days indicated Low morbidity of surgery Recurrence rates very low Accepted indications for surgical advice ○ Second ipsilateral pneumothorax ○ First contralateral ptx ○ Synchronous bilateral spontaneous ptx ○ Persistent air leak (Despite 5-7 days of chest tube) or lack of lung re-expansion ○ Spontaneous hemothorax ○ Professions at risk (pilots, i.e.) ○ Pregnancy
What is the main etiological factor pneumothorax in the context of AIDS?
PJP
Key points of pneumothorax associated with CF
- The development of a pneumothorax in a patient with cystic fibrosis requires early and aggressive treatment with early surgical referral
- Pleural procedures, including pleurodesis, do not have a significant adverse effect on the outcome of subsequent lung transplantation
- PTX more frequent with increasing age and disease severity
- Up to 3.4% of CF patients
- CT drainage has recurrence rate of 50%
- Lung may be slow to expand - mucous impaction makes for a stiff lung
- Partial pleurectomy = treatment of choice, if fit for surgery
- If not fit for surgery - chemical pleurodesis
Indications for tracheostomy
- Structural airway problems: subglottic stenosis, hemangioma, tumours, craniofacial anomalies
- Lung problems: CLD, chronic ventilation
- Neurological problems: neuromuscular, SCI, vocal cord paralysis, diaphragmatic dysfunction
When should cuffed tubes be used?
Requiring high pressures
Only nocturnal ventilation
Chronic aspiration
Recommendations for trach suctioning
- Clean technique recommended for home care
- Premeasured technique (measure until distal holes of suction catheter just exiting tip of trach tube) recommended for all routine suctioning
- Suction prn but if no evidence of secretions then minimum morning and bedtime to check patency
- Largest size catheter that will fit inside tube is recommended (usually double size of trach)
- Use pressures of 80-100 mmHg
- Rapid technique (< 5 sec) recommended to prevent atelectasis
- Routine use of N/S not recommended
Recommendation for humidification with tracts
If upper airway is bypassed then inspired air lacks humidity - loss of ciliary action, thickens secretions -impairs ventilation and increases risk of infection
Recommend humidification with e.g. HME: traps the heat and moisture from exhalation and partly returns it during inspiration (but increases dead space and resistance)
Criteria for use of a speaking valve
Speaking valve e.g. Passy-Muir: one way valve with air able to come in but not out so air is forced upwards through larynx/vocal cords to allow speech
- Tube size should not exceed 2/3 of tracheal lumen (unless using fenestrated tube)
- No aspiration risk and secretions thin
- Medically stable with patency of airway above trach
- Some ability to vocalize with trach occluded
Recommendations for decannulation
- Sequential downsizing of tube, often with partial or complete plugging of the tube (over days-weeks)
- After able to tolerate smallest tube then tube is removed
- Majority of failures occur within 12-36 hours after decannulation (may already have closure of stoma)
Complications for tracheostomy
50% will have complications from time of surgery to decannulation
Mortality < 1%
Early
- Bleeding
- Infection
- False tract
- Decannulation
- Obstruction
Late
- Decannulation - takes hrs to days to close
- Tube obstruction
- Granuloma
- Stenosis - suprastomal, stoma, at tip (secondary to infection, inflamm, pressure, mechanical irritation)
- Infection - bypassing nasal filtration (microbial aspiration) and humidification (decreases efficiency of mucociliary clearance)
- Hemorrhage - suctioning trauma or tracheoinominate fistula (risk factors: low tube tip, high pressure cuff, excessive tube movement)
- TEF - related to posterior tracheal wall injury
- Tracheomalacia - ischemic injury with subsequent weakness and destruction of supporting cartilage (reason why cuffed tubes not routinely used)
New definition of PH in children
Resting mean pulmonary artery pressure (mPAP) >20 mmHg beyond the first few months of life (> 3 most at sea level)
Definition of idiopathic PAH
pulmonary vasculopathy that remains a diagnosis of exclusion, specifically indicating the absence of diseases of the left side of the heart or valves, lung parenchyma, thromboembolism, or other miscellaneous causes.
Differences between paediatric and adult PH
1) Pediatric PH is intrinsically linked to issues of lung growth and development,
2) The development of PH in the neonate and young infant is often related to impaired functional and structural adaptation of the pulmonary circulation during transition from fetal to postnatal life.
3) Adult PH and pediatric PH differ in vascular function and structure, genetics, natural history, response of the right ventricle (RV), and responsiveness to PAH-specific therapies
The 5 classifications of pulmonary hypertension
- PAH (1’ PVOD, 1.1’’ PPHN)
- PH due to left-sided heart disease
- PH caused by lung disease or hypoxemia
- Chronic thromboembolic disease
- PH with unclear or multifactorial mechanisms
Imaging to diagnose what disorders should be done at the time of PH diagnosis
pulmonary thromboembolic disease, peripheral pulmonary artery stenosis, pulmonary vein stenosis, pulmonary veno-occlusive disease (PVOD), and parenchymal lung disease
What imaging/diagnostic modality is recommended before starting PH medications?
Cardiac catheterization is recommended before initiation of PAH-targeted therapy and should include acute vaso- reactivity testing (AVT)
What is considered to be a positive response on cath to acute vasoreactivity testing?
Positive response to AVT for children should be considered as a ≥20% decrease in PAP and pulmonary vascular resistance (PVR)/systemic vascular resistance (SVR) without a decrease in cardiac output
Pulmonary testing to consider when investigating the cause of PH
CXR
PFT
PSG
V/Q scan
Most common genetic cause for PH
BMPR2
Genetic syndromes with increased risk for PH (+/- CHD)
T21 DiGeorge syndrome Scimitar syndrome Noonan syndrome Dursan syndrome Cantu syndrome
O2 saturation goal in patients with established BPD and PH?
maintaining O2 saturations between 92% and 95% in patients with established BPD and PH
When should lung biopsy be considered for PH?
Lung biopsy may be considered for children with PAH suspected of having PVOD, pulmonary capillary hemangiomatosis, or vasculitis
When should lung transplant be considered for PH?
Referral to a lung transplantation center for evaluation is recommended for patients who have confirmed pulmonary capillary hemangiomatosis or PVOD
Preventive care measures for health maintenance are recommended for pediatric patients with PH?
Respiratory syncytial virus prophylaxis (if eligible)
Influenza and pneumococcal vaccinations
Rigorous monitoring of growth parameters
Prompt recognition and treatment of infectious
Respiratory illnesses
Antibiotic prophylaxis for the prevention of subacute bacterial endocarditis in cyanotic patients and those with indwelling central lines
Which patients with PH should not participate in competitive sports
Pediatric patients with severe PH (WHO functional class III or IV) or recent history of syncope should not participate in competitive sports
What is the most frequently noted abnormality of lung volumes in patients with respiratory muscle weakness?
Reduction in vital capacity (VC).
With marked expiratory weakness, what happens to RV?
RV is usually normal or increased, the latter particularly with marked expiratory weakness
With muscle weakness, what happens with TLC, RV/ TLC and FRC/TLC ratios?
Total lung capacity (TLC) is less markedly reduced than VC, and the RV/ TLC and FRC/TLC ratios are often increased without necessarily implying airway obstruction.
The VC is limited by weakness of both the inspiratory muscles, preventing full inflation, and expiratory muscles, inhibiting full expiration.
Reductions in compliance of both the lungs and chest wall also contribute to the reduction of VC
Vital capacity reflects the combined effect of weakness and the static mechanical load on the respiratory muscles
Im mild respiratory muscle weakness, which is more sensitive - VC or max respiratory pressure
In mild respiratory muscle weakness, VC is less sensitive than maximum respiratory pressures
In more advanced disease, marked reductions in VC can occur with relatively small changes in maximum pressures.
What happens to VC in patients with isolated or disproportionate bilateral diaphragmatic weakness or paralysis in the supine position?
In patients with isolated or disproportionate bilateral diaphragmatic weakness or paralysis, the VC shows a marked fall in the supine compared with the erect posture because of the action of gravitational forces on the abdominal contents.
Advantages of VC in measuring muscle weakness
VC has excellent standardization, high reproducibility and well- established reference values
It is quite sensitive for assessing progress in moderate to severe respiratory muscle weakness.
Disadvantages of VC in measuring muscle weakness
VC has poor specificity for the diagnosis of respiratory muscle weakness.
In mild weakness, it is generally less sensitive to changes than are maximum pressures
In uncomplicated respiratory muscle weakness, is airway resistance generally normal?
yes
Is maximum voluntary ventilation recommended for patients with respiratory muscle weakness as a measure of assessment and monitoring?
No - Maximum voluntary ventilation is not generally recommended for patients with known or suspected respiratory muscle weakness but may be helpful in the assessment and monitoring of patients with extrapyramidal disorders.
In respiratory muscle weakness, when would you expect to see daytime hypercapnia?
Daytime hypercapnia is unlikely unless respiratory muscle strength is reduced to < 40% of prediced and VS is reduced to <50% of predicted
Advantage of awake arterial blood gas in patients with respiratory muscle weakness
Advantages = Arterial blood gases assess the major functional consequence of respiratory muscle weakness.
In patients with Duchenne muscular dystrophy, hypercapnia has been shown to predict shorter survival
Disadvantage of awake arterial blood gas in patients with respiratory muscle weakness
Definitely abnormal arterial blood gases usually imply late and severe impairment of respiratory muscles
Symptoms of nocturnal hypoventilation
morning headaches, daytime sleepiness, and lack of energy.
Advantage of overnight oximetry in patients with respiratory muscle weakness
Overnight oximetry is simple to perform
Disadvantage of overnight oximetry in patients with respiratory muscle weakness
Current evidence suggests that nocturnal hypoxemia is a less good prognostic indicator than either vital capacity or awake PaCO2
3 aspects of Respiratory control
(1) sensory receptors
(2) the central integrating circuits
(3) motor output
What is occlusion pressure?
The pressure generated in the airway (and by inference the pressure generated in the pleural space) by contraction of inspiratory muscles when the airway has been occluded at end expiration.
Occlusion pressure amplitude does not directly assess either the degree of muscle weakness or the degree of neuronal adjustment to the weakness. P0.1 is the pressure generated in the first 100 milliseconds of inspiration against an occluded airway.
What is considered normal values for P0.1?
Values of P0.1 are around 1 cm H2O in normal subjects at rest, around 3 cm H2O in patients with stable chronic obstructive pulmonary disease
May be 10 cm H2O or more in acute respiratory failure due to chronic obstructive pulmonary disease or acute respiratory distress syndrome.
Reason you may see a low DLCO in a patient with respiratory muscle weakness
Reduction is due to inability to achieve full distension of the lungs at TLC and consequent failure to expose all of the alveolar surface to CO.
As with other extra- pulmonary causes of lung volume restriction, the transfer co- efficient (KCO) is often supernormal.
The pattern of normal or mildly reduced DLCO and raised KCO directs attention to extrapulmonary conditions, that is, respiratory muscle weakness, pleural disease or rib cage abnormalities.
What is the reason for the reduction in maximum oxygen consumption in patient with respiratory muscle weakness
Maximum oxygen consumption is reduced because of weakness of leg muscles rather than cardiorespiratory factors
Physiologic reasons for ventilatory failure specific to infants and newborns?
Ventilatory failure can occur in newborns and infants due to:
- immaturity of the chest wall and respiratory muscles
- poor coupling between thoracic and abdominal movements
- upper airway dysfunction.
Adults can elevate the rib cage where in infants, the ribs are already elevated and this may be one reason why motion of the rib cage during RA breathing contributes little to tidal volume
The orientation of the ribs does not change substantially until the infant assumes the upright posture.
Dynamic end-expiratory lung volume in newborns and infants is substantially above the passively determined FRC.
The inspiratory force reserve of respiratory muscles is reduced in infants with respect to adults because inspiratory pressure demand at rest is greater.
Rationale for measuring crying pressure in infants
Mouth pressures generated during crying efforts may provide an index of respiratory muscle strength in awake infants.
Airway occlusions are performed at the end or at the beginning of a crying effort to measure crying PImax and PEmax, respectively
Definition of exercise-induced bronchoconstriction. Drop in FEV1 to count?
Exercise-induced bronchoconstriction (EIB) = acute airway narrowing that occurs as a result of exercise.
The criterion for the percent fall in FEV1 used to diagnose EIB is >10%.
How is the severity of EIB graded?
The severity of EIB can be graded as mild, moderate, or severe if the percent fall in FEV1 from the pre-exercise level
Mild: >10% less then 25%
Moderate: >25% but less than 50%
Severe: >50%
Surrogates for exercise testing
Eucapnic voluntary hyperpnea or hyperventilation
Hyperosmolar aerosols (including 4.5% saline)
Dry powder mannitol.
1st line treatment for exercise-induced bronchoconstriction
An inhaled short-acting b2-agonist (SABA) before exercise.
The SABA is typically administered 15 minutes before exercise.
When is a controller agent generally added in exercise-induced bronchoconstriction?
A controller agent is generally added whenever SABA therapy is used daily or more frequently.
After regular controller, other options for add-ons for EIB
Don’t use daily use of an inhaled long- acting b2-agonist as a single therapy
Start daily administration of an inhaled corticosteroid (ICS)
Do not give ICS only before exercise
Start daily administration of a leukotriene receptor antagonist
Administration of a mast cell stabilizing agent before exercise
Administration of an inhaled anticholinergic agent before exercise
Non-pharm interventions that are recommended for EIB
Interval or combination warm-up exercise before planned exercise
For patients with EIB who exercise in cold weather, we suggest routine use of a device (i.e., mask) that warms and humidifies the air during exercise
For patients with EIB who have an interest in dietary modification to control their symptoms:
Implementation of a low-salt diet
Dietary supplementation with fish oils
Recommendation against dietary supplementation with lycopene
Dietary supplementation with ascorbic acid
What are the key roles of Nitric Oxide?
The functions and effects of NO in the lung/airways reflect its key roles as a vasodilator, bronchodilator, neurotransmitter, and inflammatory mediator.
Patients with asthma have high levels of NO in their exhaled breath and high levels of inducible nitric oxide synthase (NOS2) enzyme expression in the epithelial cells of their airways, suggesting a role for NO in asthma pathogenesis.
The pathophysiological role of NO in the airways and lungs
On the one hand, it may act as a proinflammatory mediator predisposing to the development of airway hyperresponsiveness (AHR).
On the other, under physiological conditions NO acts as a weak mediator of smooth muscle relaxation, and protects against AHR.
In exhaled air, NO appears to originate in the airway epithelium, as a result of NOS2 up-regulation which occurs with inflammation.
Thus, exhaled NO may be regarded as an indirect marker for up-regulation of airway inflammation.
Advantages for FENO
The noninvasive nature of the test
Ease of repeat measurements
The relatively easy use in patients with severe airflow obstruction where other techniques are difficult to perform
Disadvantages of FENO
The methods and equipment for measuring FENO needed to be standardized
What is the upper limit of FeNO?
We recommend that FENO greater than 50 ppb (35 ppb in children) be used to indicate that eosinophilic inflammation and, in symptomatic patients, responsiveness to corticosteroids are likely
What is the lower limit of FeNO?
We recommend that low FENO less than 25 ppb (20 ppb in children) be used to indicate that eosinophilic inflammation and responsiveness to corticosteroids are less likely
FENO values between 25 ppb and 50 ppb (20–35 ppb in children) should be interpreted cautiously and with reference to the clinical context. (strong recommendation, low quality of evidence).
What is considered a significant increase in FENO?
greater than 20% for values over 50 ppb
more than 10 ppb for values lower than 50 ppb from one visit to the next
We suggest using a reduction of at least 20% in FENO for values over 50 ppb or more than 10 ppb for values lower than 50 ppb as the cut point to indicate a significant response to antiinflammatory therapy
Definition of hypoxemia in children younger than 1 year old
Spending 5% of the recording time with SpO2 less than or equal to 90%
Definition of hypoxemia in children older than 1 year old
Spending 5% of the time with SpO2 less than or equal to 93%
When would you consider using an arterial blood gas for PaO2 assess hypoxemia?
When pulse oximetry may not accurately measure SpO2, including:
Altered hemoglobin state
Diseases affecting hemoglobin (SCD)
Definition of severe chronic hypoxemia
1) greater than or equal to 5% of recording time spent with an SpO2 less than 90% if measurements are obtained by continuous recording or
2) at least three separate findings of an SpO2 less than 90% if measurements are obtained intermittently.
A duration of 2 weeks defines chronicity of hypoxemia in a child.
Definition of mild chronic hypoxemia
1) greater than or equal to 5% of recording time spent with an SpO 2 90–93% if measurements are obtained by continuous recording
2) at least three separate findings of an SpO2 90–93% if measurements are obtained intermittently.
Risk factors for more severe BRUEs in premature infants
Central apnea longer than 30 seconds
SpO2 less than 80% for 10 seconds
Bradycardia to less than 50–60 beats per minute for 10 seconds
Upper respiratory infection symptoms
What factors can contribute to the development of severe nocturnal hypoxemia in SCD?
Hemoglobin SS is associated with more severe nocturnal hypoxemia than is hemoglobin SC, and treatment of patients with SCD with hydroxyurea is associated with improvement in hypoxemia
When should home oxygen be prescribed in CF?
Severe chronic hypoxemia
Both mild chronic hypoxemia and dyspnea on exertion
When should home oxygen be prescribed in BPD?
Chronic hypoxemia
When should home oxygen be prescribed in sleep-disordered breathing?
Sleep-disordered breathing complicated by severe nocturnal hypoxemia who cannot tolerate positive airway pressure therapy or are awaiting surgical treatment of sleep- disordered breathing
When should home oxygen be prescribed in SCD?
Severe chronic hypoxemia
When should home oxygen be prescribed in PH?
For pulmonary hypertension without congenital heart disease complicated by chronic hypoxemia
For patients with pulmonary hypertension with congenital heart disease complicated by chronic hypoxemia, supplemental oxygen will impact hemodynamics and physiology; we recommend that home oxygen therapy NOT be initiated in these children, regardless of previous reparative or palliative congenital heart surgery, until there has been consultation with a pediatric pulmonologist or cardiologist who has expertise in the management of pulmonary hypertension in this clinical setting
When should home oxygen be prescribed in ILD?
Severe chronic hypoxemia
Both mild chronic hypoxemia and dyspnea on exertion or desaturation during sleep or exertion
What is the primary source of home oxygen for infants and small children (if low flow rates and short duration)?
Size-adequate oxygen cylinders can be used in infants and small children as the primary source of home oxygen if flow rates are low (0.3 L/min) and if the duration of oxygen therapy is expected to be limited to a few months
At what flow rate is the addition of humidification recommended?
Flow rates above 1 L/min
Can be achieved through cold bubble or heated humidification devices
Most common mode of oxygen delivery?
Nasal cannula
Primary method of monitoring SpO2 in the pediatric population.
Pulse oximetry
Limitations to accurate SpO2 determinations with pulse oximeters
Improper probe placement Movement artifact Nail color Ambient light Reduced distal extremity perfusion Hypothermia Skin pigmentation Dysfunctional hemoglobin
Concerns regarding home oximetry monitoring
The nuisance of frequent alarms
Increased caregiver anxiety
The potential for overreliance by caregivers on normal SpO2 versus overall clinical status
Aspects of home safety with oxygen in the house
Risks of smoking and open flames in the home
The use of oil-based products or other fuels near the oxygen source
The focus on the dangers of exposure should include the flammability of compressed oxygen and the known harms that inhaled smoke imparts to growing infants and children
It is also imperative to ensure access to reliable electricity and a telephone in case of emergencies
Criteria for consideration of weaning home oxygen
Reassuring medical examination
Reassuring objective measurements of oxygenation (Oxygen saturation measured at steady state (not spot checked) by continuous pulse oximetry in room air)
Consider an echocardiogram to demonstrate absence of or improvement in findings suggestive of PH or right heart strain
Guidelines to wean home oxygen
It is suggested either to decrease oxygen flow rate gradually or to withdraw its use during certain periods of the day
When gradually decreasing the oxygen flow rate, it is practical to wean by halving because conventional home oxygen delivery devices easily allow for this (1 L/min to 0.5 L/min then 0.25 L/min, and so forth) before room air challenges.
We suggest weaning the flow rate gradually over the course of weeks while frequently monitoring for adverse effects.
When to consider room air challenges for those on home oxygen
Room air challenges can be considered for clinically stable children under 1 year of age receiving less than 0.1 L/min and children up to preschool age receiving 0.1–0.25 L/min.
What should you do once a patient is considered for stopping nocturnal home oxygen
In-home, room air, nocturnal pulse oximetry study should be performed
How quickly can you make changes to home oxygen?
Given the chronicity of these respiratory conditions, changes should be made on a weeks to months basis, as opposed to more quickly.
What factors to monitor that reflect those assessed when considering patient readiness
Patient growth
Development
Cardiorespiratory status
Stability of health (e.g., handling of respiratory illnesses, travel to altitude).
Definition of ILD
Nonspecific term referring to disorders that feature remodeling of the lung interstitium and distal airspaces, with resultant abnormal gas exchange.
What is considered the most prevalent sign in children with diffuse lung disease?
Tachypnea is consistently the most prevalent sign, occurring in 75–93% of patients.
Hypoxemia is also common, as are crackles and cough.
Failure to thrive is common in young children with DLD
Criteria for chILD (need 3 of 4)
(1) respiratory symptoms (cough, rapid and/or difficult breathing, or exercise intolerance)
(2) respiratory signs (e.g., resting tachypnea, adventitious sounds, retractions, digital clubbing, failure to thrive, or respiratory failure)
(3) hypoxemia
(4) diffuse abnormalities on CXR or a CT scan.
The chILD syndrome requires that more common causes of DLD have been excluded. What do these include?
Cystic Fibrosis Congenital or acquired immunodeficiency Congenital heart disease Bronchopulmonary dysplasia Pulmonary infection Primary ciliary dyskinesia presenting with newborn respiratory distress Recurrent aspiration.
3 main classifications of ILD
Disorders prevalent in infancy
Disorders not specific to infancy
Unclassified
What disorders are considered part of ILD disorders prevalent in infancy
1) Diffuse developmental disorders (ie. ACDMPV)
2) Growth abnormalities (ie. pulmonary hypoplasia)
3) Specific condition of unknown etiology (PIG, NEHI)
4) Surfactant dysfunction mutations and related disorders
What disorders are considered part of ILD disorders not specific in infancy
1) Disorders of the normal host
2) Disorders relating to systemic diseases processes
3) Disorders of immunocompromised host
4) Disorders masquerading as ILD
What disorders are considered to be part of ILD disorders unclassified
End stage disease
Non-diagnostic biopsies
Those with inadequate material
When should neonates or infants with established lung disease be investigated for potential co-existing chILD disorder
Neonates and infants who are diagnosed with one of the common diseases that can cause DLD, but whose severity of illness is out of proportion to that diagnosis, require further evaluation for coexisting chILD syndrome.
What investigations are recommended for a chILD work-up?
Echo
Thin section chest CT (CT scanning is superior to CXR at identifying DLD, and that CT scanning is superior to MRI in resolution, detecting characteristics of chILD diseases)
Infant PFT
Flexible bronchoscopy with BAL (to exclude infection or airway abnormalities as possible causes of DLD)
Cytologic studies may be useful for excluding alternative causes of DLD, such as:
Pulmonary hemorrhage syndrome Pulmonary alveolar proteinosis Pulmonary histiocytosis Sarcoidosis Niemann-Pick disease Aspiration
Findings consistent with pulmonary alveolar proteinosis should lead to an investigation for what conditions?
surfactant dysfunction mutations, GM-CSF pathway abnormalities, and lysinuric protein intolerance
Other ways of assessing for aspiration besides lipid laden macrophages
Measuring gastric pepsin levels and/or determining alveolar macrophage localization of milk proteins
When should a lung biopsy be considered for ILD?
For neonates and infants with chILD syndrome in whom other diagnostic investigations have not identified the pre- cise chILD disease, or in whom there is clinical urgency to identify the precise chILD disease, we recommend surgical lung biopsy
Biopsy should performed using video-assisted thoracoscopy (VATS) rather than open thoracotomy
VATS visualizes a greater percentage of the lung and permits the sampling of different lobes with the same incision sites. VATS also appears to be associated with less post- operative pain, shorter recovery time, and superior cosmetic results compared with a large thoracotomy incision.
For newborns who present with chILD syndrome, congenital hypothyroidism, and hypotonia consider this syndrome
NKX 2.1
For infants beyond the neonatal period who have chILD syndrome with hypothyroidism and/or neurologic abnormalities (e.g., hypotonia or choreoathetosis), or those with severe disease, a family history of adult ILD or chILD, or other features of surfactant dysfunction mutations and negative testing for ABCA3 and SFTPC, we recommend genetic testing for NKX2.1
For newborns who present with chILD syndrome leading to respiratory failure and refractory pulmonary hypertension, consider this genetic test
FOXF1 deletions or mutations
For infants beyond the neonatal period who have chILD syndrome, we recommend testing for which mutations if initial studies do not provide a diagnosis
For infants beyond the neonatal period who have chILD syndrome, we recommend testing for SFTPC and ABCA3 mutations if initial studies do not provide a diagnosis
For infants beyond the neonatal period who have chILD syndrome with alveolar proteinosis and whose genetic testing for SFTPC and ABCA3 are negative, which further testing is required.
For infants beyond the neonatal period who have chILD syndrome with alveolar proteinosis and whose genetic testing for SFTPC and ABCA3 are negative, we suggest genetic testing for CSF2RA and CSF2RB and obtaining serum levels of granulocyte- macrophage colony–stimulating factor (GM-CSF)
Some ILD that can cause severe neonatal chILD
Acinar dysplasia Pulmonary hypoplasia/alveolar simplification ACDMPV PIG Surfactant protein B ABCA3 mutation TTF-1 (NKX 2.1) mutations Pulmonary hemorrhage syndromes Pulmonary lymphangiectasia
Side effects to monitor for while on therapy for ILD
Monitor for side effects: bone density scanning, serial growth measurements, and ophthalmologic screening in children receiving chronic corticosteroids
Periodic complete blood counts and ophthalmologic evaluations in children receiving chronic hydroxychloroquine
When should infants with ILD be referred for lung transplant
Infants with chILD syndrome, diagnosis for whom a poor outcome is likely and effective treatment is unavailable should be referred to a center with experience in lung transplantation of infants to be considered for transplantation
Supportive and preventative care recommendations for chILD
Children with severe respiratory impairment due to chILD syndrome may benefit from invasive or noninvasive ventilation.
Many patients with chILD syndrome have poor somatic growth that requires nutritional intervention.
Patients with chILD syndrome should avoid harmful environmental exposures, such as second-hand smoke.
They may benefit from the pneumococcal vaccine, an annual influenza vaccination, and routine childhood immunizations, with the exception of live-virus vaccines in immunosuppressed patients.
RSV can increase the morbidity and mortality of infants and young children with chronic lung diseases such as chILD syndrome
Immunosuppressed children are routinely given prophylaxis for Pneumocystis jiroveci.
Definition of PCD
Genetically heterogeneous, autosomal recessive disorder characterized by motile cilia dysfunction.
caused by biallelic pathogenic mutations in one of the many identified PCD causative genes
4 key clinical features characteristics of PCD
1) Year-round, daily, productive (wet) cough
2) Year- round, daily, nonseasonal rhinosinusitis present early and are almost universally present by 6 months of age.
3) Neonatal respiratory distress syndrome as term newborns, defined as the need for supplemental oxygen or positive pressure ventilation support for more than 24 hours without clear explanation
Approximately 80% of children with PCD have a history of this
4) Laterality defects (e.g., situs inversus totalis), whereas other situs anomalies with or without congenital heart defects = 12% of affected individuals.
Roughly 40–55% of patients with PCD
Diagnostic tests for PCD
Previously, the diagnosis of PCD has been based on the presence of ultrastructural defects in the ciliary axoneme using TEM analysis
Nasal nitric oxide (nNO) measurement
Genetic testing
Digital high-speed video microscopy with ciliary beat pattern analysis (HSVM)
Immunofluorescence imaging for specific axonemal proteins.
Recommendations for genetic testing for PCD
In patients presenting with a strong clinical phenotype for PCD, we suggest using an extended genetic panel as a diagnostic test over TEM ciliary testing and/or standard (<12 genes) genetic panel testing
Recommendations for nasal NO for PCD
In cooperative patients 5 years of age or older with a clinical phenotype consistent with PCD and with CF excluded, we suggest using nNO testing for the diagnosis of PCD over TEM and/or genetic testing
How many nNO values need to be measured to diagnose PCD
Because nNO values may be transiently decreased with acute viral respiratory infections or sinusitis, establishing a low nNO → two separate occasions is indicated.
Can CBP analysis by HSVM be used as a replacement diagnostic test for PCD?
No - the recommendations suggest not using CBP analysis by HSVM as a replacement diagnostic test in patients with a high probability of having PCD
Common reasons for flexible bronchoscopy in children
1) Diagnostic unexplained wheeze or stridor chronic cough recurrent pneumonia microbiologic sampling suspected aspiration, structural abnormalities, endobronchial lesion OSA Radiographic abnormality Hemoptysis and pulmonary hemorrhage Monitoring of lung allograft Monitoring of artificial airway 2) Therapeutic Treatment of persistent atelectasis Control hemorrhage Bronchoscopic intubation Dilation of stenotic airway
The only absolute contraindication to flexible bronchoscopy
Refusal of the parent or guardian to provide informed consent
Consequences of flexible bronchoscopy
Minor epistaxis Partial airway obstruction Pharyngeal discomfort Minor dysphonia Cough Minor airway bleeding Transient inadvertent PEEP Transient increased ICP Transient minor fever
Complications of flexible bronchoscopy
Mechanical
(epistaxis, vocal cord spasm or trauma, significant stridor, airway trauma, hemorrhage, lower airway obstruction leading to hypoxemia, hypercapnia, air leak, bronchospasm, atelectasis)
Microbiologic
(Nosocomial infection, intrapulmonary spread of infection)
Anesthetic
(apnea, hypoxemia, hypercapnia, hypotension, nausea, aspiration, adverse drug reaction)
Multifactorial
(significant aspiration, prolonged fever >24 hours, cardiac arrhythmias, death)
Preexisting conditions essential to recognize prior to bronchoscopy include:
Hemodynamic instability Severe or uncontrolled pulmonary HTN Profound upper or central airway obstruction Immunodeficiency Infectious risk to the team (TB) Severe bronchial hyperresponsiveness Uncorrected bleeding diathesis
Medication recommendations pre bronchoscopy
May consider suspending or withholding antibiotics before the procedure to maximize the diagnostic yield of BAL.
Patients with a history of bronchial hyperresponsiveness may benefit from an inhaled short-acting b-agonist immediately before the FAE
Advantages of scoping through nose or mouth (without artificial airway)
Inspect entire airway
Assess dynamics/malacia
May allow for use of a larger scope
Allows for airway evaluation with rigid scope
Disadvantages:
more difficult to monitor ventilation and airway patency
Laryngospasm
Anesthetic waste gas into OR environment
Advantages of scoping through facemask
Inspect entire airway
Assess dynamics/malacia
Does not limit size of scope
Disadvantages:
More challenging for anesthetist than LMA or tube
Laryngospasm
May limit movement of the scope
Advantages of scoping through LMA
Easy to place
Relatively secure airway
Can assist ventilation with positive pressure
Disadvantages: Can't assess upper airway or VC movement May limit scope size Aperture bars may limit passage of scope Requires more anesthetic Can mask lower airway dynamics
Advantages of scoping through tube or trach
Faster and safer access to low airway
Secure airway
Quick to remove and reinsert scope if needed
Enable PPV and extensive suctioning
Potentially avoids contamination of lower airway with upper airway flora
Disadvantages: Can't assess upper airway or VC movement May limit scope size Requires more anesthetic Can mask lower airway dynamics
Advantages of flexible scope compared to rigid
More thorough exam of distal airway and upper lobe segments
Directed sampling by BAL
Better assessment of airway dynamics (depending on sedation)
Introduction through nasal passage, or tube (which allows for tube placement)
Advantages of rigid scope compared to flexible
Allows for introduction of instruments into the scope
Best for removal of foreign bodies
Can ventilate through the scope
Better assessment of the upper airway (assessing for laryngeal clefts etc.)
May be best for evaluation and control of brisk alveolar hemorrhage
Most frequently sampled lobes for BAL
The right middle lobe and lingula are the lung segments most frequently sampled because they provide maximal return
In evaluating children for suspected aspiration, it may be optimal to sample which segments?
In evaluating children for suspected aspiration, it may be optimal to sample segments that are normally dependent.
BAL findings of alveolar proteinosis
Gross: milky, sediment is often visible
Cytology: PAS-positive, diastase-resistant, amorphic material
Electron microscopy: Abundant extracellular multilamellated bodies and tubular myelin structures, alveolar macrophages with enlarged foamy cytoplasm
BAL findings of alveolar hemorrhage
Gross: bloody, increasing with each sample
Cytology: hemosiderin laden macrophages
BAL findings of Langerhans Cell Histiocytosis
Immunostaining for S-100, CD1a, langerin
BAL findings of Chronic Lipoid Pneumonia
Oil Red O staining with scoring for lipid-laden macrophages
BAL findings of Pulmonary Alveolar Microlithiasis
Microlith staining with PAS or von Kossa stain
The medical home for the ventilator dependent child must provide these things
Subspecialty management of the child’s chronic respiratory failure and its treatment including all aspects of ventilator management and associated therapies
Support for technical aspects of the ventilator and tracheostomy
Appropriate training of family caregivers
Access to care 24h/d, 7d/wk
Community -based primary care
Coordination of all aspects of the child’s care
Guidance to patient/family on all aspects of the child’s medical care
Providers responsible for comprehensive care assessment and management of all aspects of the child’s health care
Proposed standardized criteria for discharge of an invasively ventilated child to home
The child must be medically stable for discharge
Caregivers must demonstrate willingness and ability to look after the child
A DME company must be available and able to provide the required equipment and technical support
Professional in home caregivers as required to support family must be arranged before discharge
The home and community environment must be safe and allow access to routine and urgent care as needed
