Clinical studies

Substantial differences are expected between patient-ventilator interactions in pressure support ventilation and proportional assist ventilation as a consequence of variations in ventilatory requirements. In mechanically ventilated patients during weaning, the strategy used to compensate for increased ventilatory requirements due to CO2 stimulation substantially differed during pressure support ventilation and proportional assist ventilation ( Ranier ยง[email protected] 1996). An increase in minute ventilation is obtained by increasing respiratory rate in the former and by increasing tidal volume in the latter. When the energy cost, evaluated as the product of esophageal pressure and time, of such different strategies is compared, a larger amount of inspiratory muscle effort is required to increase minute ventilation in response to hypercapnic stimulation during pressure support ventilation than during proportional assist ventilation. Patient discomfort also appears lower during proportional assist ventilation. Finally, non-invasive proportional assist ventilation has been used to alleviate distress and avoid intubation in patients with acute respiratory failure; early use of proportional assist ventilation resulted in the avoidance of intubation in eight of eleven patients with acute respiratory failure of different etiologies.

Sleep Apnea

Sleep Apnea

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