COMPARATIVE-EVALUATION OF DIAPHRAGMATIC ACTIVITY DURING PRESSURE SUPPORT VENTILATION AND INTERMITTENT MANDATORY VENTILATION IN ANIMAL-MODEL

The aim of the present study is a comparative evaluation of the effect s of pressure support ventilation (PSV) and intermittent mandatory ven tilation (IMV) on diaphragmatic activity in rabbit model of neonate. T he animals were divided into a PSV group and an IMV group. In the IMV group, spontaneous breathing and four kinds of IMV rate (5, 10, 15, an d 20/min) were applied (Ventilator: Bear BP200, peak inspiratory press ure [PIP]: 12 cm H2O, inspiratory time: 0.6 s). In the PSV group, spon taneous breathing and four levels of PSV (3, 6, 9, and 12 cm H2O) were applied (Ventilator: VIP Bird, flow triggering). Airway pressure (Paw ), flow (V), esophageal pressure (Pes), integrated diaphragmatic elect romyogram (Edi), and arterial gas data were measured. Amplitudes of Pe s and Edi were expressed as percentages (%Edi and %Pes) of the control value during spontaneous breathing to evaluate diaphragmatic activity . Lower IMV rates did not reduce diaphragmatic activity. Approximately half of diaphragmatic activity of control remained even at IMV 15/min . Diaphragmatic activity disappeared at IMV20/min. In contrast, PSV re duced Edi and Pes linearly according to support level. In conclusion, diaphragmatic activity could be reduced more gradually with PSV than I MV by altering ventilatory support level.