Noninvasive positive pressure ventilation in trauma patients with acute respiratory failure

The effectiveness of noninvasive pressure support ventilation (NIPSV) in treating trauma patients with acute respiratory failure (ARF) was evaluated in a retrospective clinical study. Forty-six conscious patients with ARF admitted to the general intensive care units (ICUs) of three hospitals between July 1988 and July 1991 were surveyed. Patients received NIPSV after a period of spontaneous breathing with supplemental oxygen. Blood gas levels and respiratory parameters were measured before the application of the mask and after 1, 6 and 12 h of NIPSV. Thirty-three (72%) patients were successfully weaned to spontaneous breathing (success group). Nine patients with hypercapnia and four with hypoxaemic respiratory failure failed to respond to prolonged mask ventilation and were intubated (failure group). Of the 13 patients who failed NIPSV, nine died after switching to invasive ventilation after a mean time of 10 +/- 3 days. No deaths occurred during NIPSV. A mean pressure support ventilation (PSV) of 11.7 +/- 4.2 cmH2O and positive end-expiratory pressure (PEEP) of 4.5 +/- 2.7 cmH2O were required to significantly increase arterial oxygen tension (Pa,O2)/inspiratory oxygen fraction (Fi,O2) from 152.4 +/- 41.7 (spontaneous breathing) to 277.9 +/- 108.7 (NIPSV) (p < 0.01) within the first hour. The expiratory tidal volume (VT) increased from 356.1 +/- 103.7 (spontaneous breathing) to 648.1 +/- 77.1 mL (NIPSV) (p < 0.01) with a concomitant reduction in the respiratory frequency (fR) from 31.4 +/- 5.2 (spontaneous breathing) to 20.4 +/- 4.3 (NIPSV) without significant differences between the success and failure group. In the 22 patients who were hypercapnic at the point of entering the study, the arterial carbon dioxide tension (Pa,CO2) decreased from 73.0 +/- 1.0 kPa (52.5 +/- 7.8 mmHg) (spontaneous breathing) to 5.5 +/- 1.0 kPa (41.5 +/- 7.5 mmHg) (NIPSV) (p < 0.01) and pH increased from 7.29 +/- 0.05 to 7.33 +/- 0.04 (p < 0.05). The median length of time of use of NIPSV was 55.5 h (range 6-144). In conclusion, noninvasive pressure support ventilation might effectively be used in a selected group of trauma patients as a means of treating respiratory failure.