Background: Proportional assist ventilation (PAV), a new mode for assist ventilation, allows the patient not only to trigger the ventilator but enables him to keep his breathing pattern. The basis of PAV is a positive feed back between patient and ventilator.
Patients and method: PAV was applied in 6 patients, who were under long-term ventilation and who were stable. The ventilator was adjusted to compensate for the endotracheal tube, different parts between 90 and 40% of resistance and elastance were assisted. Airway pressure, flow and tidal volume were measured. PAV was compared with pressure support ventilation (PSV).
Result: No difference in blood gases were found in PAV as compared to PSV. Airway pressure were lower in PAV than in PSV (10.4 +/- 3.3 cm H2O vs. 18.8 +/- 5.9 cm H2O in PSV). Breathing frequency was higher (22.4 +/- 8.1 vs. 15.8 +/- 5.9 in PSV).
Conclusion: The higher breathing frequencies in PAV were associated with the underlying diseases and resulted in a better synchronisation with the respiratory center output.