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%)
