[The effect of positive end-expiratory pressure on gas exchange and hemodynamics]

The effects of positive end-expiratory pressure (PEEP) on arterial and mixed venous blood oxygenation as well as the effects on systemic and pulmonary circulation were studied in 15 patients with adult respiratory distress syndrome (ARDS) on mechanical ventilation. The measurements of arterial and mixed venous blood oxygen pressure (PaO2, PvO2), heart rate (HR), central venous pressure (CVP), pulmonary wedge pressure (WP), mean pulmonary arterial pressure (Ppa), mean systemic arterial pressure (Psa) and cardiac output (CO) were performed at 0, 5, 10 and 15 cm H2O PEEP. The positive effect of + 10 cm H2O on arterial oxygenation was found (PaO2 raised from 11.49 +/- 3.5 kPa to 13.3 +/- 3.3 kPa). Ppa raised too, from 23 +/- 7.6 mm Hg to 26 +/- 7 mm Hg. Psa and CO lowered at + 15 cm PEEP. Psa from 85 +/- 17 mm Hg to 73 +/- 17 mm Hg as well as CO from 8.22 +/- 1.1 l/min to 6.91 +/- 1.40 l/min. Authors conclude that PEEP can be accepted form of therapy in the treatment of refractory hypoxemia in patients with ARDS. Despite this beneficial effect, PEEP may adversely affect cardiovascular function. As with any therapy, the optimum PEEP "dose" should be tailored to each patient according to his needs and response.