EFFECTS OF PRESSURE-SUPPORT VENTILATION ON RECOVERY FROM ACUTE DIAPHRAGMATIC FATIGUE IN RABBITS

Objectives: To examine the effects of pressure-support ventilation on recovery from acute diaphragmatic fatigue, Design: Prospective laborat ory trial, Setting: Experimental laboratory. Subjects: Twenty-one heal thy, adult New Zealand white rabbits, Interventions: Diaphragmatic fat igue was induced with 50 Hz phrenic nerve stimulation for 30 mins, Rec overy was compared between pressure-support ventilation 0 cm H2O (SB), 10 cm H2O (P10), and 20 cm H2O (P20) for 90 mins immediately after th e end of the fatigue inducing procedure. Measurements and Main Results : After the fatigue inducing procedure, pressure-support ventilation r educed transdiaphragmatic pressure and integrated diaphragmatic electr omyogram both at P20 and P10, but not in SE. Recovery was assessed by airway occlusion pressure (Poccl) generated by high- (100 Hz) and low- (20 Hz) frequency phrenic nerve stimulation. Poccl at 100 Hz was lowe r in P10 and P20 than in SE (74.6 +/- 6.2 [SEM] %, 66.9 +/- 3,3%, and 94.8 +/- 3.6% of the baseline at 90 mins for P10, P20, and SE, respect ively), while those at 20 Hz showed no differences between the three g roups, Conclusion: Recovery from acute diaphragmatic fatigue might be disturbed with pressure-support ventilation.