Clinical application of differential ventilation with selective positive end-expiratory pressure in adult respiratory distress syndrome.

Differential ventilation in the lateral position with positive end-expiratory pressure (PEEP) selectively applied to the dependent lung (DVSP) has been shown to reduce venous admixture and improve oxygenation without compromising cardiac output in short term studies of patients with acute respiratory failure. We have applied this ventilation technique as a long-term treatment in severe adult respiratory distress syndrome (ARDS) in an open clinical trial. Eleven patients with ARDS of varying aetiology were treated with DVSP for a total of 34 days. Median duration of conventional ventilatory therapy before start of DVSP was 5 days (1 to 18 days), inspiratory oxygen fraction (FIO2) was 0.61 +/- 0.16 (mean +/- s.d.), resulting in a mean arterial oxygen tension (PaO2) of 7.1 +/- 2.1 kPa (PaO2/FIO2 = 11 +/- 4 kPa). A gradual improvement in gas exchange was seen during the first 24 h of DVSP such that PaO2 increased to 8.4 +/- 1.4 with a decreased FIO2 (0.52 +/- 0.14) resulting in an increased PaO2/FIO2 (16 +/- 5 kPa). Five out of the eleven patients survived. No major complication was noted using DVSP as a method. We found a steady improvement in gas exchange over the first 24 hours in most patients. However, mortality rate was no lower than expected. Drawbacks with DVSP were increased demand on staff and difficulties with adequate endo-bronchial suctioning.