Patient Comfort During Pressure Support and Volume Controlled-Continuous Mandatory Ventilation

BACKGROUND: Pressure-support ventilation (PSV) is more comfortable than volume controlledcontinuous mandatory ventilation (VC-CMV) in acute hypercapnic respiratory failure, in patients undergoing noninvasive ventilation. Physiologic measurements of patient status have been compared in PSV and VC-CMV in endotracheally intubated patients, but patient perception of comfort has not been measured in this population.

OBJECTIVE: To determine if PSV is more comfortable than VC-CMV (volume-cycled, flow-limited) in intubated mechanically ventilated patients.

METHODS: In a randomized prospective trial, patients underwent PSV and VC-CMV for 30 min each, separated by a 30 min washout with the baseline ventilation mode (pressure-regulated volumecontrol ventilation “PRVC”). The level of pressure support was set as the plateau pressure on VC-CMV with a tidal volume of 8 mL/kg minus the end-expiratory pressure. After each mode the patient was asked to mark his or her comfort level on a visual analog scale.

RESULTS: Eleven of the 14 patients were more comfortable during PSV. The baseline mean comfort score (during PRVC) was 62 ± 18 (95% confidence interval 51.7–72.5). The mean comfort score for PSV was 83 ± 11 (95% confidence interval 76.9–89.6). The mean comfort score for VC-CMV was 70 ± 18 (95% confidence interval 59.4–79.9). PSV was significantly more comfortable than VC-CMV (p = 0.02) or PRVC (p = 0.009), whereas the comfort scores for VC-CMV and PRVC were not significantly different (p = 0.278). Respiratory rate, blood pressure, heart rate, minute ventilation, and blood oxygen saturation showed no difference between PRVC, VC-CMV, and PSV.

CONCLUSIONS: On average the patients felt more comfortable during PSV than during VC-CMV or PRVC, so PSV may be the preferred mode for awake intubated patients.