NIV and Glottis-diaphragm Synchrony
NIV and Glottis-diaphragm Synchrony
Noninvasive ventilation (NIV) can provide ventilatory support in selected patients with acute
 respiratory failure, for instance due to acute exacerbation of COPD and acute heart failure.
 Advantages of noninvasive ventilation compared to invasive mechanical ventilation include
 absence of complications associated with endotracheal intubation, lower risk of pneumonia,
 lower level or even absence of sedation and the ability of the patient to verbally
 communicate. However, in approximately 30% of patients NIV fails and endotracheal intubation
 is needed to provide optimal ventilatory support. Surprisingly, very few studies have
 investigated why patients fail on NIV. Clinical observations indicated that agitation,
 delirium and most importantly asynchrony between patient and ventilator play a role in
 unsuccessful support with NIV. The upper airways are bypassed during endotracheal intubation.
 However, with NIV the upper airways may play a role in the efficiency of ventilatory support.
 In normal breathing the upper airways actively dilate before initiation of inspiratory flow.
 This is a highly appropriate response as it prevents narrowing of the upper airways during
 inspiration, which would result in elevated inspiratory resistance. Experiments in newborn
 lambs have shown that NIV has profound effects on physiology of the upper airways. Positive
 pressure during inspiration results in constriction of upper airway muscles in the early
 phase of inspiration. This results in elevated upper airway resistance with lower tidal
 volume delivered to the lungs. Subsequent studies revealed that reflexes that mediate this
 response originate in vagal afferences located in the lower airways. From an evolutionary
 point of view this might be an appropriate response, as high pressure delivered to the lungs
 may induce barotraumas. However, these responses may negatively affect the efficiency of
 ventilatory support delivered during NIV. The understanding of upper airway constriction and
 dilation during NIV is rudimentary. This study aims at determining the effect of NIV on
 regulation of upper airway patency in patients with COPD.
Inclusion Criteria:

 -  Informed consent

 -  COPD

 -  Hypercapnic respiratory acidosis

 -  Clinical need of NIV ventilation on the intensive care

 -  NAVA catheter in situ

 Exclusion Criteria:

 -  Pre-existent muscle disease (congenital or acquired) or diseases / disorders known to
 be associated with myopathy including auto-immune diseases.

 -  Diabetes

 -  Upper airway/esophageal/mouth or face pathology (i.e. recent surgery, esophageal
 varices, diaphragmatic hernia)

 -  Recent (< 1 month) nasal bleeding

 -  Allergic to xylocaïne