Combined nitric oxide inhalation, prone positioning and almitrine infusion improve oxygenation in severe ARDS

To determine the efficacy and side effects of prone positioning (PP) and nitric oxide (NO) inhalation, alone, associated, or combined with i.v. almitrine for the treatment of hypoxaemia in severe acute respiratory distress syndrome (ARDS).

Over a period of 20 months, 27 consecutive critically ill patients with severe ARDS (Murray score > 2.5, PaO2/FiO2 < 170 after alveolar recruitment) were prospectively and randomly included. They inhaled NO for two hours at concentrations of 5 and 10 ppm for one hour each (H0-H2). One hour later, they were returned to the prone position for four hours (H3-H7). During the last two hours in this position (H5-H7), they were assigned to further inhalation of 10 ppm NO (Group B, n = 9) or to no further inhalation (Group A, n = 9). In group C (n = 9), the procedure for group B was combined with perfusion of 16 mg.kg-1.min-1 almitrine throughout the study.

Compared with control values, two hours NO inhalation improves PaO2/FiO2 and shunt effect by +28% and -9%, PP by +88% and -27%, PP + almitrine by +132% and -28%, NO + almitrine by +153 and -28%, PP + NO by +94% and -29%, NO + PP + almitrine by +327 and -48%. NO inhalation reduces pulmonary vascular resistance. Other haemodynamic parameters remain unchanged, whatever the treatment. NO inhalation improves PaO2/FiO2 by over 20% in 50% of the patients and PP is effective in 78% of the cases.

Prone Position improves PaO2/FiO2 significantly more than NO alone but less than PP + almitrine or NO + almitrine. The best results are obtained with the association of NO + Prone position + Almitrine.