Improved Arterial Oxygenation and CO₂ Elimination Following Changes from Volume-Generated Peep Ventilation with Inspiratory/Expiratory(I/E) Ratio of 1:2 to Pressure-Generated Ventilation with I/E Ratio of 4:1 in Patients with Severe Adult Respiratory Distress Syndrome (ARDS)

Abstract

In earlier investigations we found that in severe ARDS caused by bilateral lung lavages in adult rabbits and dogs, the arterial oxygenation increases when constant pressure-generated ventilation with decelerating flow and an I/E ratio 4:1 was applied (1,2,3). This specific ventilation pattern was therefore used in 6 patients with severe ARDS who could not be sufficiently oxygenated with PEEP ventilation. Three of them had such severe damage to the lung parenchyma with gas leakage that PEEP pressure higher than 4–8 cm H₂O could not be administered. In two patients, PEEP higher than 12–16 cm H₂O had no influence on oxygenation. In one patient with myocardial re-infarction, a PEEP higher than 8 cm H₂O led to acute cardiac failure. Before the special ventilation pattern was started, all of the patients were ventilated with volume-controlled ventilation with an I/E ratio of 1:2 or 1:1. An FIO₂ of 1 had been used for an average of 72 h.