Intrapulmonary percussive ventilation superimposed on spontaneous breathing: a physiological study in patients at risk for extubation failure.

PURPOSE

Intrapulmonary percussive ventilation (IPV) is a high-frequency ventilation modality that can be superimposed on spontaneous breathing. IPV may diminish respiratory muscle loading and help to mobilize secretions. The aim of this prospective study was to assess the short-term effects of IPV in patients at high risk for extubation failure who were receiving preventive non-invasive ventilation (NIV) after extubation.

METHODS

Respiratory rate, work of breathing, and gas exchange were evaluated in 17 extubated patients during 20 min of IPV and 20 min of NIV delivered via a facial mask, separated by periods of spontaneous breathing. The pressure-support level during NIV was adjusted until tidal volume reached 6-8 ml/kg and positive end-expiratory pressure (PEEP) 4-5 cmH(2)O. For IPV, the pressurisation frequency was set at 250 cycles/min and driving pressure at 1.2 bar. The pressure-time product of the diaphragm (PTPdi/min) was measured using an oesophageal and gastric double-balloon catheter.

RESULTS

Transdiaphragmatic pressure and PTPdi/min improved significantly (p < 0.01), from a median [25th-75th percentiles] of 264 [190-300] to 192 [152-221] cmH(2)O s/min with IPV and from 273 [212-397] to 176 [120-216] cmH(2)O s/min with NIV. Respiratory rate decreased significantly from 23 [19-27] to 22 [17-24] breaths/min for IPV and from 25 [19-28] to 20 [18-22] breaths/min for NIV (p < 0.01). Mean PaCO(2) decreased after NIV (from 46 [42-48] to 41 [36-42] mmHg, p < 0.01) but not after IPV. There was no noticeable effect on oxygenation.

CONCLUSIONS

IPV is an interesting alternative to NIV in patients at risk for post-extubation respiratory failure. Both NIV and IPV diminished the respiratory rate and work of breathing, but IPV was less effective in improving alveolar ventilation.