Does the cycling-off criteria of pressure support change the respiratory parameters in intensive care unit patients?

Introduction

In modern mechanical ventilators it is possible to modify the flow cycling-off criteria of pressure support ventilation. The changes in the flow cycling-off criteria of pressure support ventilation can modify the synchrony between the mechanical and neural inspiration termination.

Objective

To compare the effects of two different flow cycling-off criteria of pressure support ventilation on the respiratory parameters of ICU mechanically ventilated patients.

Methods

We prospectively evaluated 20 intubated and mechanically ventilated adult ICU patients recovering from acute respiratory failure that could be comfortably ventilated with pressure support of 15 cmH₂O, PEEP of 5 cmH₂O and FIO₂ of 40%. The patients were ventilated at two different cycling-off criteria of pressure support of 25% and 40% of the peak inspiratory flow. We evaluated the respiratory rate (RR), expiratory tidal volume (V_Te), minute ventilation (MV), VCO₂, VTCO₂, ETCO₂, SpO₂, mean arterial pressure (MAP) and heart rate (HR).

Results

Comparisons between different cycling-off values did not result in any statistically significant changes for the evaluated variables. There were no significant changes in blood pressure or HR under any experimental conditions (Table 1).

Table 1 Respiratory and hemodynamic variables measured with two cycling-off criteria (25% and 40%)

Conclusion

The changes in cycling of criteria from 25% to 40% of the peak flow did not affect the respiratory parameters in mechanically ventilated patients in a mixed ICU.