Traumatic respiratory insufficiency: comparison of conventional mechanical ventilation to high-frequency positive pressure with low-rate ventilation.

Eleven patients suffering severe traumatic respiratory insufficiency were mechanically ventilated using a new system which combined high-frequency positive-pressure ventilation (HFPPV) with low-rate conventional mechanical ventilation (LRCMV). Ten similar patients were ventilated by conventional mechanical ventilation (CMV) with PEEP. HFPPV patients were fully conscious and cooperative during ventilation and did not need sedatives or muscle relaxants. Arterial oxygenation was significantly (p less than .005) better in HFPPV than CMV patients (89.91 +/- 10.24 vs. 78.43 +/- 11.13 torr, respectively), and pulmonary shunt was also better in the HFPPV group (13.1 +/- 4.7% vs. 20.4 +/- 6.4%, p less than .01). Moreover, inspired oxygen concentrations were lower (PaO2/FIO2 197.8 +/- 51.3 in the HFPPV group vs. 130 +/- 46.6 in the CMV group, p less than .005) and the time required for mechanical ventilation was shorter (4.2 +/- 0.91 vs. 6.1 +/- 0.8 days, p less than .1). All HFPPV patients immediately began breathing spontaneously when they were disconnected from the ventilator. We suggest this method as a better ventilatory mode for patients suffering traumatic respiratory insufficiency.