NIV Flashcards
Reasons for biPAP instead of CPAP?
Rate - eg. late onset CCHS such as ROHAD
For providing positive inspiratory pressure in patients with hypoventilation, such as neuromuscular disease
What questions could you ask to figure out clinical significance of a patient’s sleep disordered breathing?
Daytime functioning - tiredness, neurocognition, development
Pulmonary hypertension
Growth
What is the definition of periodic breathing?
Rule of 3s.
Periodic breathing, defined as three episodes of apnea lasting longer than 3 seconds and separated by continued respiration over a period of 20 seconds or less, is a common respiratory pattern in preterm neonates, and may also be highly prevalent in full-term newborns.
Non-pathologic. Improves over first year of life.
Interstingly:
These pauses may be accompanied by modest oxygen desaturation and bradycardia that do not require clinical intervention
Breathing abnormality in Rett’s?
- Abnormal breathing while awakeThis is a key point!! Awake is the issue for this type of breathing, though can also happen while asleep
- Hyperventilation and hypocapnea alternating with hypoventilation/apnea during which they may have oxygen desaturation
- Breathing is normal in between episodes
- Hypoventilation/apnea can last 20-120 seconds
- During hyperventilatoin: child is excited or agitated
- During hypoventilation/apnea: child doesn’t appear distressed, they may even be calm and smiling
- No associated bradycardia
- There can be severe cyanosis and EEG seizures
What are risk factors for SIDS?
●Maternal factors:
- Young maternal age
- Maternal smoking during pregnancy
- Late or no prenatal care
●Infant and environmental factors:
- Preterm birth and/or low birth weight
- Prone sleeping position
- Sleeping on a soft surface and/or with bedding accessories such as loose blankets and pillows
- Bed-sharing (eg, sleeping in parents’ bed)
- Overheating
What are some pediatric disease that can lead to sudden death?
CCHS, long QT syndromes, fatty acid oxidation defect like VLCAD
What is a typical pressure and number of cycles for cough assist?
Pressure of +/- 30-40 with 3-5 maneuvers
Methods for decreasing saliva production in children with salivary aspiration?
Anticholinergic: glycopyrrlate, atropine drops, scopolamine patch
Botulinum toxin injection of salivary glands
Salivary gland ligation or removal
Strategies for mucous plugging in patient with trach?
- Ensure appropriate size tracheostomy tube (e.g, would upsizing tracheostomy be appropriate?)
- Ensure adequate humidification to avoid thickened secretions (e.g, utilization of humidified circuit, addition of normal saline or sodium bicarbonate drops to thin secretions) – Art nose or HME
- Reduce secretions (e.g,. pharmacologically – atropine drops, glycopyrrolate, scopolamine patch, surgically – e.g,. Botox injections of salivary gland, ligation or removal of salivary glands). n.b. risks and benefits of pharmacologic management must be carefully considered, as they can make secretions thicker which could cause increased difficulty with obstruction.
Or if thick secretions: hypertonic saline
Chest physio: manual percussion, cough assist
Pulmonary complications of achondroplasia?
Main issues are related to sleep disordered breathing:
Reasons for sleep disordered breathing:
- Anatomic abnormalities such as midface hypoplasia, micrognathia, depressed nasal fridge, relative adenotonsillar hypertrophy, relative macroglossia, high palate, decreased TMJ mobility leads to OSA
- Hypotonia contributes to OSA
- Narrow forman magnum and cervical cord compression can lead to central sleep apnea and risk of sudden death
- AAP advises: neuroimaging (either CT or MRI) and PSG at diagnosis
- PSG at birth/diagnosis and then as indicated
- Neuroimaging at birth/diagnosis and then as indicated
Other pulmonary manifestations of achondroplasia:
Obesity, which can worsen OSA
- Lower on list of manifestations: restrictive lung disease in first 3 years of life (due to narrow chest wall and kyphosis)
What is obesity hypoventilaton syndrome and why does it occur?
Obesity hypoventilation syndrome (OHS) is defined as the presence of awake alveolar hypoventilation (arterial carbon dioxide tension [PaCO2] >45 mmHg) in an obese individual (body mass index [BMI] ≥30 kg/m2) which cannot be attributed to other conditions associated with alveolar hypoventilation (eg. neuromuscular disease).
Mechanisms contributing to OHS:
- There are compensatory mechanisms that normally exist in the obese individual to maintain eucapnea
- OHS happens when these compensatory mechanisms fail
- There need to be compensatory mechanisms because in obesity:
- Increased CO2 production due to increased body surface area
- V/Q mismatch with poor ventilation of lower lobes of lungs with persevered perfusion→hypoxemia, hypercapnea
- Breathing pattern characterized by high RR and low tidal volume→more anatomic dead space and CO2 accumulation
- Restriction
- Muscle weakness
- In OHS:
- Reduced neural drive—obese individuals with eucapnea have higher neural drive than non-obese individuals. Having lower than this compensatory level of increased drive can result in OHS
- Leptin resistance—leptin is produced in adipose tissue and stimulates ventilation
- Many patients with OHS have associated OSA, though this is not the case for 10% of patients
- Hypoventilation first starts during sleep in patients with obesity, typically during REM sleep
What is the PSG definition of a central apnea?
- Drop in signal excursion by >=90% from pre-event baseline + absent inspiratory effort throughout the entire duration of the event
- Signal device: oronasal thermal sensor
- One or more of the following:
- Duration: >=20 seconds
- At least 2 breaths with associated arousal
- At least 2 breaths with associated desaturation of >=3%
- At least 2 breaths and associated decrease in heart rate <50 x 5 seconds or <60 x 15 seconds (this would be the duration for infants)
What is the PSG definition of an obstructive apnea?
- Drop in signal excursion by >=90% from pre-event baseline
- Signal device: oronasal thermal sensor
- Duration: at least 2 breaths
- Respiratory effort during entire period of cessation of airflow
What are causes of central hypoventilation?
- Tumor
- Infection
- Bleed
- CNS infarct
- Metabolic disorder
- Myelomeningocele
- Arnold chiari malformation type 2
- Congenital (CCHS)
- Last onset congenital hypoventilation syndrome due to a trigger like pneumonia, obesity, cor pulmonale. ROHAD : rapid onset obesity, hypothalamic dysfunction, hypoventilation and autonomic dysregulation
- Syndrome: Prader willi syndrome
Symptoms and signs of OSA?
Related to upper upper airway obstruction:
- Snoring
- Witnessed apneas
- restlessness
- diaphoresis
- difficulty breathing, mouth breathing
- abnormal sleep posture
Related to morbidity (consequences)
- elevated BP
- enuresis
- excessive daytime sleepiness
- inattention/hyperactivity
- cognitive deficits
- academic difficulty
- failure to thrive
- (morning headache)
How does thoracic imepedence monitoring work? What can be it used for? What are the disadvantages?
- the same electrodes that are used for ECG heart rate monitoring are used to send a small current through the chest wall
- breathing motions will change the impedence–>voltage change
- if there is no breathing, then no voltage change–>monitor will alarm
- used for infant apnea (particularly central apnea monitoring)
- Disadvantages to using this monitoring in the home environment:
- not able to detect obstructive apnea
- other signals will cause change in impedence like normal cardiac activity and motion–>machine will think the patient is breathing, even though the patient isn’t breathing. There cases where machine has failed to detect apneas of 50 seconds and infants have died
- parental anxiety, false sense of reassurance
- no evidence that it prevents sids (it’s important to let parents know this, this is not an indication for prescription) –>there’s actually better ways of preventing SIDS (supine positioning, firm mattress and having no soft objects in the crib, eliminate prenatal and postnatal smoke exposure)
• AAP 2003:
routine home apnea monitoring is not recommended, in particular for infants with ALTE/BRUE or siblings of infants who had SIDS
they do say that in select preterm infants, home apnea monitoring may be recommended in infants till 43 weeks or till extreme apneic events subside
they also say that home apnea monitoring is recommended in infants who are technology dependent (eg. invasively ventilated, NIV) at home
Key points: home apnea monitoring has NOT been proven to prevent SIDS and so it should not be prescribed for SIDS prevention
What causes hypoventilation?
Central: Congenital central hypoventilation, ROHAD, opioid use
Thoraco-skeletal (chest wall abnormality)
NeuroMuscular
Severe airway disease like asthma or COPD
What is the definition of hypoventilation, as based on PSG?
PCO2>50 mmHg for >25% of total sleep time. (CO2 either based on blood gas or surrogate, so presumably end tidal or transcutaneous
Does normal oximetry rule out obstructive sleep apnea?
No, it doesn’t
Children may have obstruction, but if there is a higher arousal threshold, then they will wake up before they desaturate
How do we stage the severity of OSA on PSG?
Mild: 1.5-5
Moderate: >5-10
Severe: >10
What was the key finding of the CHAT study?
- In school age children of 5-9 years with OSA, but with no prolonged oxyhemoglobin desaturation and not on medication for ADHD, who were randomly assigned to watchful waiting or T+A and re-evaluated at 7 months:
- No significant difference in the primary outcome of attention and executive function
- Differences were noted for secondary outcomes such as behaviour, quality of life, normalization of PSG
- Even in children within the watchful waiting group, about 1/2 had normalization of PSG at time of follow up
With respect to oximetry for OSA, is oximetry more sensitive or specific?
- More specific
- Not very sensitive
- The positive predictive value, combined with clinical history, is high
- The negative predictive value is only 50%
Which patients need post operative monitoring after adenotonsillectomy?
- > 3 drops in saturation to <85% (corresponds to a score of 3 or 4 on McGill)
- AHI>=24 (this is definitely in the severe category)
- hypercapnea
Maybe consider for other postoperative risk factors:
- younger than age 3 years
- severe OSA, as detailed above
- cardiac complications
- failure to thrive
- obesity
- craniofacial abnormality
- neuromuscular disease
(This is from McGill scoring system and AAP guideline)
In an infant with OSA, what sorts of underlying syndromes can be predisposing?
- Pierre robin sequence
- Down syndrome
- Neuromuscular
- Laryngomalacia
- Choanal atresia
- Achondroplasia
- Beckwith wiedmann
- Prader willi
- Chiari malformation
- Mucopolysaccharidoses
What is different about REM sleep compared to other sleep stages?
- Low muscle tone
- More blunted (less steep of slope) response to CO2 compared to other sleep stages
What is the effect of changes in PaO2 and PaCO2 on brain blood flow?
- Hypoxia will cause increased cerebral blood flow
- High CO2 (hypercapnea) will cause increased cerebral blood flow
What are the changes that occur in sleep in healthy people?
- decreased ventilatory drive
- decreased muscle tone in upper airway and intercostal muscles
- the above is true for all of sleep, but worse during REM sleep
- these changes are worse during REM sleep
Why should a neuromuscular patient with nocturnal hypoxemia and hypoventilation not be treated with just oxygen?
- CO2 is our main drive to breathe
- with chronic hypercapnea, there can be a diminished ventilatory response to CO2, so more reliant on hypoxemia as a drive to breathe
- if you just give them oxygen, then there is nothing to trigger their drive to breathe
What is the stepwise progression of timing for hypoventilation in a patient with neuromuscular disease?
- Hypoventilation during REM sleep
- Hypoventilation during REM and non-REM
- daytime hypoventilaton
What are the benefits of NIV in children with neuromuscular disease?
- Nocturnal hypoventilation
- Daytime hypoventilation
- Decrease admissions to hospital
- Prolong survival
- Prevent chest wall deformity
General indications for intubation in a patient with NMD?
- Airway protection: severe bulbar dysfunction causing aspiration
- Failure to extubate–>inability to extubate after an acute event, despite optimal management for 2 weeks or more
- Ventilatory support needed for more than 16 hours per day
- Failure to correct hypoxemia or hypercapnea on NIV
- Severe midface hypoplasia that can’t be corrected by changing interface
Early, non-ambulatory DMD patient. How often do you want to see them in clinic and what measurements should be done?
- twice annually
- FVC (seated FVC), peak cough flow, MIP, MEP, SpO2, transuctaneous or end tidal CO2
DMD patient with OSA who needs NIV. What type of NIV do you start? CPAP or BPAP?
start BPAP since they will eventually need it anyways
Indication for cough augmentation in patients with DMD?
- FVC<50%
- MEP<60
- peak cough flow <270 L/min
Indication for nocturnal ventilation in patient with Duchenne?
- FVC<50%
- MIP<60
(the old guideline said if signs/symptoms of hypoventilation, patients with FVC<30% at higher risk) - Baseline saturation of <95% or end tidal/blood gas CO2>45 while awake
Sleep study indications:
PETCO2 or PtcCO2 is >50 mmHg for at least 2% ofsleeptime
*
Sleep related increase in CO2 of 10 mmHg above baseline for at least 2% of sleep time
*
SpO2 <=88% for at least 2% of sleep time or 5 min continuously
*
AHI >=5
Indications for daytime ventilation in kid with DMD?
- symptoms of hypoventilation with sats<95% or CO2>45 while awake
- self extension of ventilation into daytime hours
- inability to speak full sentence without breathlessness
- abnormal swallowing due to dyspnea, which is relieved by ventilatory assistance
Indications for tracheostomy in patient with DMD?
- patient preference
- inability to use NIV successfully
- inability of local infrastructure to support NIV
3 failed extubation attempts during criticial illness, in spite of optimal use of NIV and mechanically assisted cough- aspiration of secretions into lungs due to bulbar weakness, causing drops in saturation or frequent suctioning
What are the respiratory complications in patients with neuromuscular disease?
- Low muscle tone, including maintenance of upper airway tone–>OSA
- The respiratory pump is weak–>hypoventilation
- Secretion clearance–>retain secretions, lower airway infection
- Airway protection–>aspiration
- Scoliosis and restrictive lung disease
Should nebulized mucolytics like pulmozyme, 3% saline, 7% saline be used in patients with neuromusclar disease on a regular, chronic basis?
No. Their mucous is normal, in contrast to a patient with CF. Thinning secretions can result in excessive secretion burden.
(Traditional airway clearance is thought to be an important part of dealing with secretion retention and is recommended as part of regular management for SMA patients)
SMA type 1–>frequency of clinical assessment, investigations and management?
- seen every 3 months initially, then every 6 months
- assessment of pulse oximetry, end tidal/transcutaneous CO2
- early PSG
- want to be proactive with initiation of NIV, ideally before they are symptomatic
- chest physiotherapy + cough assist, oral suctioning–>this implemented immediately. (this is in contrast to duchenne where initiation of cough assist is based on peak flow; with SMA type 1, there is respiratory failure by 2 years of age, so you need to be proactive.
What are the FVC thresholds that are associated with the stepwise progression of respiratory failure in patients with neuromuscular disease as a whole ?
- FVC<60%–>associated with REM related hypoventilation
- FVC<40%–>REM and non-REM hypoventilation
- FVC<20%–>daytime ventilatory failure
(this is from a combination of BTS general neuromuscular guideline and the SMA guideline)
At what peak cough flow should cough assist be initiated?
- peak cough flow<270 (this recommendation is consistent with between BTS neuromuscular, SMA and duchenne guideline), though with SMA type 1 you initiate mechanical cough assist right away b/c of rapidity of progression
What is the change in lung volumes seen in patients with neuromuscular disease?
- Decrease TLC
- Normal or low FRC
- relative sparing of residual volume because of expiratory muscle weakness (you can’t blow down to a lower residual volume)
- Don’t need to do full lung volumes, can just look at vital capacity, which would be slow or forced
In the patient with neuromuscular disease, what are the complications of restriction?
- Poor clearance of secretions
- the lung is sitting on a less favorable portion of the compliance curve
- hypoventilation
Patients with ILD also have restriction and low lung volumes. Why is there no hypoventilation?
- there is no weakness of respiratory muscles. they have a normal residual volume
- they are able to maintain minute ventilation
- they may be tachypneic–>when the lung is stiff, there is a lot of elastic work of breathing. even though being tachpyneic will result in more resistive work of breathing, this will actually be less than the elastic work of breathing
In which neuromuscular patients is lung volume recruitment not advised?
- patients with obstructive airway disease since there is a risk of barotrauma. (this is why looking at FEV1/FVC is important for neuromuscular patient)
what does a more than 25% drop in FVC between upright and supine indicate?
indicates diaphragm weakness
For the purpose of initiating an infant with BPD on home oxygen, how is chronic hypoxemia defined?
- Recording of >=5% that is <=93%
- 3 separate findings of saturation <=93%
- (The problem is that the oximetry does not break it down for <93%)
Target saturation for infant with BPD and PH?
92-95% (AHA guideline, ATS home oxygen guideline)
For the purpose of providing home oxygen, how is chronic hypoxemia defined for most disease states?
- saturation is <90% for >=5% of the time
- 3 separate saturation values <90%
(this threshold is slightly different than how ATS defines normal saturations)
Indication for cough assist in duchenne?
non-ambulatory stage and
FVC<50% or
peak cough flow<270 or
MEP<60 (Lancet 2018 duchenne guideline)
Indication for LVR in patient with Duchenne?
- non-ambulatory stage + FVC<=60%
indication for nocturnal ventilation with Duchenne?
- signs of symptoms of hypoventilation or sleep disordered breathing
- abnormal daytime ventilation: awake baseline saturation of <95% or pCO2<45 mmHg
- abnormal sleep study findings:
- PETCO2 or PtcCO2 is >50 mmHg for at least 2% ofsleeptime
- Sleep related increase in CO2 of 10 mmHg above baseline for at least 2% of sleep time
- SpO2 <=88% for at least 2% of sleep time or 5 min continuously
- AHI >=5
Indication for daytime ventilation in Duchenne?
- Indication for starting daytime ventilation, if during the day if despite nocturnal ventilation:
* CO2 (either end tidal or transcutaneous or venous/arterial or capillary gas) >45 mmHg * baseline SpO2 <95% on room air
OR if symptoms of awake dyspnea
indications for tracheostomy in duchenne?
- patient preference
- inability to use NIV successfully
- 3 failed extubation attempts during criticial illness, in spite of optimal use of NIV and mechanically assisted cough
- aspiration of secretions into lungs due to bulbar weakness
Minimum Peak cough flow for a healthy person. Minimum PCF for an effective cough.
2 ways to increase PCF.
- Normal cough flow in healthy adults: >=400 L/min
- Peak cough flow>160 is needed for effective secretion clearance
- Peak cough flow>270 is needed for resilience to respiratory infections (would be vulnerable to respiratory failure) –><270 in child >=12 years is the threshold for some sort of assisted cough
- We do NOT have values for cough flow in children (I think this is why they don’t recommend using it till the age of 12 years)
To increase peak cough flow:
- Lung volume recruitment- eg. bagger, Air stacking / Volume recruitment
- Manually assisted cough with Chest compression
- Mechanical insufflation/exsufflation
What is the difference in the type of paradoxical breathing caused by intercostal muscle weakness (relative diaphragm sparing) versus diaphragm muscle weakness.
- With normal breathing, chest wall and abdomen should move in same direction on inspiration and expiration
- Intercostal muscle weakness with diaphragm sparing (eg. this is the case with SMA): still generate a negative intrapleural pressure, chest wall is sucked in and abdomen is pushed out. Reduced FVC, low MIP and MEP
- diaphragm muscle weakness with intercostal sparing (eg. duchenne, diaphragm paralysis, end stage respiratory failure since diaphragm is more affected than intercostals): outward chest wall movement, abdomen moves in (since diaphragm can’t push it down). Low FVC, MIP is more affected than MEP
Pulmonary manifestations of duchenne?
- restrictive lung disease (due to neuromuscular weakness, scoliosis, obesity)
- decreased peak cough flow and risk of LRTI
- hypoventilation
- OSA
- obesity
- scoliosis
- aspiration
- associated cardiomyopathy
Advantages and disadvantages of end tidal versus transcutaneous CO2?
End tidal:
- Advantage: real time with breath by breath changes in CO2
- Disadvantage: not accurate if patient is mouth breathing, cannula can get occluded by secretions
Transcutaneous: advantage: accuracy is not affected by mouth breathing, supplemental oxygen or mask ventilation.
disadvantage: poor seal on skin pick up, not real time breath to breath variability in CO2 because the signal has a longer response time compared to end tidal
When should patients with DMD be routinely evaluated for sleep disordered breathing?
2012: annual evaluation, ideally with PSG, when patients are wheelchair bound
(2018 guideline does not specify when screening PSG should be started)
- If we extrapolate from the general neuromuscular BTS guideline, then FVC<60%–>annual PSG is ideal
What cobb angle of scoliosis corresponds to restrictive disease?
- Cobb angle >50 –>restriction
- Cobb angle >60–>nocturnal hypoventilation
- Cobb angle >90–>cardiorespiratory failure
When is the ideal time for surgery in DMD and scoliosis?
In DMD, progressing cobb angle of >20 degrees and at least FVC 40% is indication for surgical management since bracing is not effective in these patients (Kendig’s). (2012 guideline said Cobb angle of 30-50 degrees)
- no absolute contraindication based on pulmonary funciton
(ideal time is before lung function is bad and before cardiomyopathy has set in)
- of note, scoliosis usually becomes worse in non-ambulatory stage
- bracing doesn’t work, so have to go to surgery
DMD patient going for scoliosis surgery. What preoperative evaluation should happen?
- reviewed by respirology and cardiology, anaesthesia 2 months prior to surgery
- assess for sleep hypoventilation pre op, ideally with PSG
- PFT, spO2, CO2
- optimize nutrition
- consider initiating LVR, cough assist or NIV
- consider extubation directly to non-invasive
- scoliosis surgery: posterior spinal fusion
In DMD patient, what is the impact of scoliosis on lung function? What are the benefits of scoliosis surgery?
Scliosis surgery:
- the goals of scoliosis surgery are not about the lungs, the goals is: minimize progression, decrease pain,improve sitting tolerance
Effect of scoliosis surgery on lung function:
- short term:
Surgery doesn’t improve FVC , in fact there is evidence to indicate it might decrease FVC temporarily
The decrease in vital capacity usually lasts for 6 weeks to 3 months after fusion but can persist for up to 1 year
- spinal fusion may slow progression of respiratory decline, but some studies show no difference in rate of respiratory decline
How do we monitor respiratory function in patients with DMD? When does respiratory function usually decline?
- see patients every 6 months if non-ambulatory
- every 12 month visit if ambulatory
- FVC, peak cough flow, MIP, MEP, oxygen saturation, PETCO2
- annual PSG when non-ambulatory and we could extrapolate from other neuromuscular guidelines about FVC<60%
- lung function goes down at 10-12 years when there is loss of ambulation
What are the benefits and side effects of steroids used in DMD?
- steroids should be started at the plateau phase, about 4-8 years
- benefits:
- ambulatory: prolongs ambulation, slows cardiac, respiratory, orthopedic compications
- even when patients are non-ambulatory, steroids slow the rate of progressive of scoliosis and help with stabilizing pulmonary function
- Side effects:
- obesity
- hypertension
- adrenal insufficiency
- glucose intolerance
- GERD
- cataract
- bone demineralization and risk of fracture
Initial settings for biPAP titration in sleep lab?
- S/T (spontaneous timed mode–>patient has the opportunity for sponanteous breaths, but there is a back up rate
- 8/4
- back up rate 2-4 breaths below spontaneous rate
- titrate PS based on tidal volume (<6-8 mL/kg) and if PCO2 remains persistently elevated or saturation <90%
In a patient with scoliosis or who is wheelchair bound, what can we use as a surrogate for standing height?
- arm span
In which patients with scoliosis should you consider routine PSG?
- cobb angle >60
In general, does scoliosis surgery improve lung function?
- No
- seems reasonable to extrapolate the approach in duchenne–>no significant change in FVC, but treating the scoliosis may halt progression, slow rate of decline, pain, quality of life indications
Change in lung function after surgery:
* Change in lung function: * decreased vital capacity for 6 weeks to 3 months after fusion, but can last for 1 year * by 1-2 years post, vital capacity is back to where it was preop * some patients may need longstanding biPAP support after
3 categories of scoliosis and which one is the most common type?
● Congenital ,
● Idiopathic - (infantile , juvenile and adolescent) and ,
● Scoliosis associated with neuromuscular disease
Most common is the idiopathic scoliosis (85%)
- What is the prevalence of idiopathic adolescent scoliosis in the general population
2-3%
- scoliosis is defined by cobb angle greater than 10 degrees
Name 1 respiratory complication and 1 cardiac complication that you expect to see from Scoliosis
Restrictive lung disease and pulmonary hypertension
scoliosis is a 3D phenomenon, many sources comment on cardiorespiratory compromise, mitral valve prolapse is also seen
What determines Restriction severity in scoliotic patients
Cobb angle
Presence of associated neuromuscular problems – there will be additional restriction from neuromsucular weakness
Age of onset (lung hypoplasia) –earlier age of onset is associated with lower FVC for the same cobb angle
- What are the PFT abnormalities that you expect to see and what is the most sensitive marker of reduced thoracic cage and mobility?
Decreased FVC, normal ratio, decreased TLC and normal or increased RV/TLC since TLC is more decreased than RV
Most sensitive marker of reduced thoracic cage mobility is FVC (Kendig)
Decreased MIP
Indications for treatment in scoliosis?
● Cobb Less than 25 and non progressive , wait and watch
- if Cobb angle is more than 25 - 50 and non progressive –>bracing
- when cobb angle is more than 50 or progressing despite bracing in idiopathic scoliosis–>surgery
- the above holds true for adolescent idiopathic scoliosis
● In duchenne (and potentially other neuromuscular disease) bracing avoided, surgery when Cobb >20 and FVC <40%
● Surgery- Growth friendly distraction technique before bone growth is complete and spinal fusion after spine growth is complete
● In congenital scoliosis - serial casting until 5 years followed by growth friendly distraction surgery
Post op scoliosis surgery complications?
Bleeding , fluid shifts causing pulmonary edema , pneumonia, Atelectasis, Multifactorial respiratory failure related to pain, sedation, analgesia, restriction, fat embolism etc
Does the cobb angle in scoliosis predict the degree of lung restriction?
No
What electrodes are used during PSG?
From Reshma article:
Electroencephalogram (EEG): The AASM recommends F4-M1, C4-M1 and O2-M1;
contralateral leads are typically applied as well (F3-M2, C3-M2 and O1-M2).
• Electromyogram (EMG): Submental and bilateral tibial
• Electrooculogram (right and left)
• ECG
• Nasal pressure
• Oronasal airflow (thermistry)
• End-tidal PCO2
• Arterial oxygen saturation (SpO2) with pulse waveform
• Chest and abdominal wall motion
• Body position monitor
• Snoring microphone (optional)
• Video
From notes:
- EEG (3 locations - frontal, central, occipital)
- EOG (extraocular, 2 leads)
- Chin EMG - 3 leads
- intercostal EMG
- ?diaphragm EMG
- limb EMG (to look for periodic leg movements)
- ECG/HR
- SpO2
- nasal pressure transducer (this is used for determination of hypopnea)
- thermal airflow sensor (this is moustache sticker)
- chest wall band
- abdominal wand
- TcO2 +/- EtCO2
What are features of different sleep stages ?
NREM1: theta waves – low amplitude, mixed frequency waves (4-7 Hz – so lower frequency than with alpha rhythm when people are awake. Alpha rhythm is 8-13 Hz)
NREM2: sleep spindles, K-complexes
NREM3: slow wave sleep, delta waves (high voltage, low frequency) – restorative
You shouldn’t be seeing a lot of eye movements for N1, N2, N3
REM: low amplitutde mixed frequency EEG, saw tooth pattern (looks similar to alpha waves when awake), sharp eye movements, decreased chin activity, muscle atonia – memory consolidation - more respiratory events usually (20%) (remember that tone is decreased so that you aren’t acting out your dreams)
practically, you will see an abrupt drop in chin tone with REM movements
In general, how is apnea described on PSG?
- Based on oronasal thermal airflow sensor, drop in peak signal intensity by at least 90% for 2 breaths
How is desaturation on PSG defined?
> =3% decrease in saturation
Definition of hypopnea on PSG?
- decrease in peak signal excursion by >=30% for at least 2 breaths
- This decrease in signal is based on the nasal Pressure transducer (think P for hypopnea and pressure)
- associated desaturation (>=3%) or arousal
Definition of periodic breathing on PSG?
- > =3 episodes of central apnea lasting >3 seconds, separated by <=20 seconds of normal breathing
definition of hypoventilation on PSG?
> 25% of TST with CO2>50
pCO2, etCO2, tcCO2 >50mmHg > 25% of recording time
Definition of desaturation on PSG?
-drop in SpO2 >3% from baseline or <90%
Definition of OSA severity on PSG?
OSA SEVERITY Pediatrics (can use to <18 years old): < 1.5 = normal 1.5 – 5 = mild 5 – 10 = moderate >10 = severe
Adults (can use if > 13 year old at discretion): < 5 = normal 5 - 15 = mild 15 - 30 = moderate >30 = severe
Look at sleep notes on other brainscape
to do
What is the definition of ROHAD?
- rapid onset obesity, hypothalamic dysfunction, autonomic dysfunction, sleep related breathing disorders (eg. OSA, nocturnal hypoventilation, central apnea), negative test for PHOX2B (which is seen with CCHS), normal brain MRI, no other mutation that could account for these abnormalities
3 year old child with rapid onset weight gain (20-30 pounds in 6 months), new onset hypothyroidism. What’s the on the differential?
- very important to consider ROHHAD and have a high index of suspicion b/c these kids can die from cardiorespiratory arrest
- PSG abnormalities: OSA, central apnea, hypoventilation
- most common initial PSG abnormality is OSA
- even if no hypoventilation on initial PSG, very important to do a follow up PSG in case the patient actually has a diagnosis of ROHHAD–basically, it’s a diagnosis of exclusion
- can’t find a guideline for how frequently PSG should be done
- rapid onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation
- rare disease, high mortality rate 50-60% with cardioresp arrest
- no specific diagnostic test, clinical Dx
1. Excessive weight gain (20-30lbs) over 6-12mo in young child beginning 2-3yo
2. May have: neuroendocrine tumor, hyperprolactinemia, central hypothyroidism, disordered water balance (diabetes insipidus), failed GH stim test, temp dysregulation, gastric dysmotility, hypotension.
3. SRBD – OSA, CSA, abn response to CO2/ hypoventilation - *predisposed to cardiac arrest**
- hypoventilation is essential, but it can evolve over time, other symptoms presenting first
- may initially present only with OSA, and develop nocturnal hypoventilation + dysfunctional day-time breathing later (centrals with desaturations)
What types of hypothalamic and autonomic abnormalities can be associatd with ROHHAD?
- hypothalamic: hyperprolactinemia, hypothyroidism, hypernatremia, polydipsia, hyperphagia, growth hormone deficiency, adipsia, adrenal insuffiicency, diabetes insipidus
- autonomic dysregulation: bradycardia, thermal dysregulation, GI dystmotility, hypotension, tumor of neural crest origin
Criteria for narcolepsy?
- Type 1: with cataplexy
- Type 2: without cataplexy
- DDX for EDS
- consider atypical presentations of cataplexy
- need absence of other SRBD or it is adequately treated
Type 1 – A & B criteria must be met
A. daily periods of irrepressible need to sleep or daytime lapses into sleep >3mo
B. one or both of
1. Cataplexy AND a mean sleep latency of <8 minutes and 2 or more sleep onset (w/in 15 minutes of sleep onset) REM on MSLT. SOREM on PSG night before can replace one above.
2. CSF hypocretin-1 concentration, measured by immunoreactivity <110pg/mL or <1/3 of mean values in normal subjects during the day
** in children, Narcolepsy can present as excessively long night time sleep or as resumption of previously discontinued day-time napping.
** if narcolepsy type 1 suspected, but B of criteria not met, the MSLT should be repeated.
Type 2 – A through E criteria must be met
A. daily periods of irrepressible need to sleep or daytime lapses into sleep >3mo
B. mean sleep latency of <8 minutes and 2 or more sleep onset (w/in 15 minutes of sleep onset) REM on MSLT. SOREM on PSG night before can replace one above.
C. Cataplexy is absent (if cataplexy develops later – can chg Dx to type 1)
D. CSF hypocretin has not been measured OR CSF hypocretin-1 concentration, measured by immunoreactivity <110pg/mL or <1/3 of mean values in normal subjects during the day
E. Hypersomnolence and/or MSLT findings are not better explained by: insufficient sleep, OSA, delayed sleep phase disorder, effect of medications/ substances.
Describe features of CCHS.
-central chemoreceptor dysfunction
-leads to central apneas during sleep, and prolonged breath-holding in the day
-PSG early (<1 year old) then repeat as indicated
-avoid swimming, etOH, drugs
-caution with illness, bc classic tachypnea/ distress not always apparent
Vent support :
-PPV with trach in first several years of life
-possibility of decannulation and nocturnal NIV at 6-8yrs earliest
Diaphragm pacing
Non- Resp Complications:
-Hirschsprungs
-Neuroendocrine tumors
-Neurocognitive deficits
-Asystole
-Other autonomic dysfunction
Monitoring:
-q6mo PSG, echo (LVH, cor pulmonale), 72hr holter (until 3 years)
-q1 year PSG, echo (LVH, cor pulmonale), 72hr holter
-q3mo until 2yrs, then q6mo till 7 years, then q1yr abdo imaging, and urine catecholamines
-q1yr chest and abdo imaging
-annual neurocognitive assessments
Considerations from ventilation SMA? (
- hypoventilation from +++ chest wall weakness 🡪 high CO2
- atelectasis from chest wall and diaphragm weakness 🡪 low SpO2
- early BiPAP improves prognosis – SMA-1 (helps prevent chest wall rigidity)
- early PSG as possible
NIV in all symptomatic infants, prepare for resp failure, helps prevent chest wall distortion, palliate dyspnea
CPAP should not be used, but with caution to maintain FRC, and when trouble syncing
Extubate from, higher pressures, to NIV, and once room air
CXR: parasol chest, ribs angle down
(Jody’s notes)
Considerations for ventilation in prader willi?
- CSA more common in infancy when hypotonic/ poor feeding
- should resolve with age
- gets better with oxygen therapy
- PSG early (<1 year old) then repeat as indicated
- OSA more common in childhood when obesity and still hypotonic
- growth hormone starts need PSG pre, then after 6months on treatment -
- sleep studies and treatment needed
Considerations for ventilation in Rett, Joubert, MPS?
Mucopolysaccharidoses (MPS)
- group of inherited syndromes – Hurler=MPS1, Hunter=MPS2
- Hurler = macroglossia, limited mouth opening, T&A hypertrophy, laryngeal mucosal deposits, tracheal GAG deposits, neurodegenerative. Hunter similar, less severe.
- multilevel airway obstruction 🡪OSA, daytime obstruction +/- tracheostomy
- PSG indicated depending on GOC/ etc.
Rett Syndrome (MECP2 deletion)
- can have CSA or OSA
- breathing abnormalities awake include (CNS dysregulation of breathing):
- central apneas
- hyperpnea 🡪 hyperventilation 🡪 hypocapnea
- Neuro can be involved to Rx Fluoxetine, Buproprion
- can also have aspiration due to swallowing dysfunction or GERD
- ILD has been reported
- low threshold for PSG
Jouberts Syndrome
- breathing abnormalities with sleep AND awake
- central apneas
- hyperpnea
- triad of: developmental delay, hypotonia resp rhythm abnormalities
- ciliopathy syndrome
- molar tooth sign on MRI
- PSG indicated early
(Jody notes)
Considerations for ventilation in patient with sickle cell?
- upper airway obstruction can occur due to
- racial difference in face shape – mid-face hypoplasia
- face bone medullary hematopoiesis
- adenoid and tonsil hypertrophy (increased due to compensation for asplenia)
- usually no OSA unless history of snoring or EDS (excessive daytime sleepiness)
- concern with OSA and hypoxia 🡪 triggers sickling
- SpO2 may be lower at baseline bc HbS shifts your oxygen dissociation curve to the right (to promote oxygen unloading from hemoglobin – so can be even lower with sleep
- Hydroxyurea increase % HbF which shifts your curve to the left, and increases SpO2
- PSG if symptomatic: snoring +/- EDS
Consideration of ventilation for achondroplasia?
- foramen magnum stenosis
- risk of brainstem herniation or compression of the medulla
- risk of inc ICP from dec CSF flow
- CSA can cause early death
- OSA possible – midface hypoplasia, nerve impingement
- PSG early (<1 year old) then repeat as indicated
Jody’s notes
Considerations for ventilation in T21?
- can have central and obstructive apneas
- hypopnea is still important
- Hx says they don’t snore – can not trust history of just no snoring in T21
- Screen at 4yo/ <5yo - if PSG perfect - unlikely to get more TA hypertrophy
- if symptoms do first PSG sooner
- no repeat testing unless symptoms or obese
- at risk of obesity/ OSA +/- hypoventilation in adolescence
- important to watch kids with history of PHTN that has resolved, at high risk to have recurrence of PHTN secondary to OSA.
Jody’s notes
How is daytime hypercapnea defined?
pCO2>45
Indications and physiologic effect of CPAP?
- Pneumatic stent to keep the upper airway open
- pressure is also transmitted down to lower airways–>prevent lower collapse, increases FRC, reduce LV afterload (this is why it is used in cardiac patients), reduces work of breathing
Not considered a true ventilator since it doesn’t actively assist inspiration
Indications for biPAP?
Indications:
- chronic hypercapneic respiratory failure
- CPAP not tolerated
- CPAP doesn’t get rid of upper airway obstruction
IPAP:
- decreases work of breathing, decreased respiratory rate, reduce PaCO2
EPAP:
- eliminate upper airway obstruction
- improve oxygenation
- most ventilation in the home is pressure targeted ventilation
Contraindications to NIV?
- unable to protect upper airway and adequately manage secretions
- bulbar dysfunction
- significant GERD and aspiration risk
- unable to tolerate PAP
- lack of sufficient caregiver support
- use of PAP>=16 hours per day
- unable to find interface with good fit
- recent upper airway or craniofacial surgery
What are the interface options for NIV?
- Nasal
- Nasal pillow - not available for infants or younger children
- oronasal
- full face - lots of deadspace, higher chance of CO2 rebreathing but all the masks have an intentional leak to prevent re-breathing of CO2
Why is breakdown of sleep stages important?
REM is the most sensitive time for detecting obstruction and hypoventilation, so if not enough time in REM then you would miss detecting these abnormalities. Often, for the first night in sleep lab, ther is a “first night” effect wiht less REM sleep
complications of PAP therapy?
- skin erythema and breakdown, skin necrosis
- midface hypoplasia
- gastric insufflation and risk of aspiration (consider venting G tube if they have one)
- nose bleeds, nasal congestion (make sure that humidifer is being used)
- eye irritation if there is leak
- rebreathing of exhaled CO2, which is more likely if full face or oronasal
- pulmonary air leak - such as in patients with CF or apical blebs
- Cardiac effects:
- increased intrathoracic pressure–>decreased venous return and less cardiac output. this is relevant for patients who are hypovolemic or single ventricle
- pulmonary hyperinflation–>increased vascular resistance–>decreased left ventricular filling and cardiac output. –>for most patients, the cardiac complications are not a big deal
How would you initiate CPAP or BPAP in the sleep lab?
CPAP: start at +4 and titrate. Shouldn’t need oxygen unless there is associated lung disease
BPAP: S/T (sponanteous/timed) mod, start at 8/4, I time 0.8-1.5 seconds, BUR 2-4 breaths below patient’s spontaneous rate, medium trigger, medium cycle. There should always be a minimal delta of 4
What is trigger, cycling and synchrony on the ventilator?
- trigger: patient’s ability to initiate/trigger a breath
- terminate/cycle: ability to terminate a breath and cycle to the next breath
- synchrony: machine is doing what the patient wants
- autocycling = over triggering, would want to adjust trigger level
Bipap and not tolerating it, what are the causes?
Blowing into the eyes Poor mask and headgear fit High leak Inappropriate settings Not de-sensitized with mask Poor sensing - dyssynchony Lack of humidification
Differential for central hypoventilation?
Drugs - narcotic, anticonvulsant
Infection
Metabolic - hypoglcemia, fatty acid disorder, metabolic alkalosis
Structural - CNS hemorrhage, Arnold chiari malformation type 2, myelomeningocele
Intrinsic: congenital (CCHS), late onset (ROHAD)
Sleep related breathing abnormalities in prader willi syndrome?
- Increased amount of REM sleep
- Disturabances in circadian rhythm and excessive daytime sleepiness
- Obesity and hypotonia—>OSA
- Absence of ventilatory response to peripheral chemoreceptor stimulation—>abnormal arousals during sleep
- Obesity reduces central chemoreceptor sensitivity, which is improved with growth hormone
- But there has been sudden death in PWS kids started on growth hormone
- Need to do overnight PSG before initiation of GH in child with PWS, repeat PSG in a few weeks and yearly
What is late onset central hypoventilation?
- A trigger such as: pneumonia, severe obesity or cor pulmonale cause hypoventilation
- ROHAD - rapid onset obesity with hypothalamic dysfunction, hypoventilation and autonomic dysregulation
Gene for CCHS?
PHOX2B (autosomal dominant)
Diagnostic criteria for CCHS?
- There has to be evidence of hypoventilation with no other obvious cause for hypoventilation: no neuromuscular disease, cardiac disease, pulmonary disease
- Hypoventilation (paCO2>60) - in particular during quiet sleep
- onset in first year of life
- Hypercapneic ventilatory challenge—it sounds like this is part fo the diagnostic criteria (not sure if this is separate from PSG)
- Investigations while waiting for genetic results:
- Metabolics - inborn error
- MRI brain
- Echo
- CXR +/- CT
Monitoring for complications of CCHS:
- Cardiac: heart block, prolonged sinus pauases, pulmonary hypertension–>annual 72 hour Holter and echo
- Hirschpsrung disease–>clinical monitoring. If concerning symptoms, then contrast enema and rectal suction biopsy
- Cognitive deficits–>Annual neurocognitive assessment
- Tumors of neural crest origin:
- NPARM: abdo imaging and urine catecholamines q3 months for first 2 years, then q6 months till age 7 years, (then every year)
- PARM with 20/28-20/33: annual chest and abdominal imaging
- PSG: every 6 months till age 3 years, then every year
- All patients: annual echo, Holter, neurocognitive assessment
Supplies for emergency tracheostomy kit?
- Obturator of current tube
- Two extra tracheostomy tubes - current size and size below
- Fully charged suction machine, suction catheters
- Normal saline syringes for installation
- Prepared trach ties
- emergency alogirthm
- phone number
- bagger with mask (self inflating mag with mask) and connector if child is ventilated
manual resuscitation device with same size and size smaller, tracheostomy tube, tracheostomy tube ties, suction machine, suction catheters , suction catheters, Normal saline, water soluble lubricant, scissors, tape, medical information and an ambu bag if possible.
The Go Bag should be checked on a routine basis and these equipments (except for the suction machine) should not be used except for an emergency.
Contraindications/relative contraindications for NIV
- Recent facial or upper airway surgery or burn
- Poor glottic function and inability to protect the upper airway
- Patient preference
- CCHS, requiring ventilation during infancy - since they would require ventilation for significant portion of day and developmental concerns
- copious respiratory secretions
Neuromuscular patient with viral illness who comes into hospital. Baseline saturation of 93%.
Need to implement cough augmentation techniques like cough assist if saturation <95% on room air (either with or without NIV). Cough assist has been shown to decrease chance of intubation.
Lung volume recruitment maneuvers for patient with NMD?
- Stacked breaths (no exhalation in between inspiration) via:
- Lung volume recruitment bag
- volume cycled NIV
- Glossopharyngal breathing
Methods for cough augmentation in NMD?
Inspiration:
* Stacked breaths (no exhalation in between inspiration) via:
* Lung volume recruitment bag
* volume cycled NIV
* Glossopharyngal breathing
Expiration:
* Manual chest wall or upper abdominal thrust
* Mechanical exsufflation with negative pressure
Which method of cough augmentation is most effective?
Mechanical insufflation/exsufflation
Respiratory considerations in a patient with neuromuscular disease?
- Ineffective cough clearance–>airway clearance (eg. cough assist)
- Swallowing dysfunction–>tube feeding, sialorrhea
- Sleep disordered breathing during REM sleep–>non-REM SDB and hypoventilation so use of NIV
Later progression to diurnal hypercapea->daytime ventilation (?invasive ventilation)
(See alogirthm for more details)
Describe components of cough reflex arc
Receptor:
- mechanical receptors from pharynx to terminal bronchiole, diaphragm, pleura. Chemical receptors - eg. capsaicin
Affarnet: vagus, glossopharyngeal
Cough centre: medulla pons
Effarent: vagus, phrenic, spinal motor nerve to diaphragm, abdominal wall muscles
