Airway occlusion pressure

The most common causes of failure to wean include chronic obstructive pulmonary disease (COPD) exacerbations, neuromuscular diseases, h) oxic respiratory failure, post surgical complications (2), and heart failure. Weaning from the tracheostomy must consider the balance of respiratory muscle function and work of breathing. The work of breathing is determined by ventilatory demand, compliance of the lungs and chest wall, airway resistance, and intrinsic positive end-expiratory pressure (PEEPi). Adequacy of ventilatory drive and neuromechanical output can be assessed from the respiratory rate, airway occlusion pressure at 100 milliseconds (Po.i), maximum inspiratory pressure (MIP), and maximum voluntary ventilation (MW). 

Sasoon C, Mahutte C, and Te T, et al (1988) Work of breathing and airway occlusion pressure during assisted-mode mechanical ventilation, Chest 93 571-576,1988. 

Figure 1 A beagle dog was anesthetized with propofol and etomidate and intubated. One 250-mL breath of ammonia vapor above an 8-M ammonia solution was administered to the dog. The end-tidal COj shows an apnea followed by rapid, shallow breathing. The arterial pressure tracing demonstrates the short-lived decrease in heart rate and attendant hypotension. The transpulmonary pressure illustrates that the apnea and tachypnea was due to the absence of ventilatory drive, rather than airway occlusion.

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