Although numerous descriptions of the clinical application of pressure support ventilation (PSV) have been published, few studies have compared delivery by different ventilators. We compared the efficacy of PSV as provided by the Hamilton Veolar and the Puritan-Bennett 7200a in 8 patients.
Methods
Patients were randomized to receive PSV initially by the Veolar (Group I) or 7200a (Group II) at PSVmax (PSV set to deliver VT = 10-12 mL/kg and f < 20). After 2 hours, patients were switched to the opposite ventilator and after a 2-hour period on the second ventilator were switched back to the initial ventilator for 2 more hours. The last 30 minutes of each 2-hour period were used for data collection. During data collection, ventilatory volumes, respiratory frequency, inspiratory time, airway pressures, oxygen consumption, carbon dioxide production, and arterial blood gases were measured.
Results
During ventilation with the 7200a, patients received a significantly larger tidal volume, or VT, (for Group I, p < 0.017; for Group II, p < 0.028) and longer inspiratory time, or TI, (for Group I, p < 0.023; for Group II, p < 0.031) compared to ventilation with the Veolar. Other measured variables (including blood gases, minute ventilation, and respiratory frequency) were unchanged. CONCLUSION: The 7200a provides a longer TI and larger VT than does the Veolar due to its lower inspiratory termination criterion (5 L/min vs 25% of peak flow). Both ventilators perform well in the PSV mode, and no clinically appreciable differences were noted.
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