Mechanical ventilation in the prone position: A strategy for acute respiratory failure after cardiac surgery

Ventilation in the prone position, initially introduced in respiratory therapy to improve the drainage of secretions, has been used in intensive care to improve oxygenation. We report a case of an obese male patient who underwent elective coronary artery bypass grafting and had low PaO₂ in the postoperative period. The PaO₂ improved whenever the patient was ventilated in the prone position. On each occasion, oxygenation improved without any change in the hemodynamic parameters. The PaO₂ increased from 57.8 to 249.7 mmHg on the first occasion, from 48.7 to 194.6 mmHg on the second and 62.5 to 199.7 mmHg on the third at an FIO₂ of 1.0. The shunt fraction (Qva/Qt) decreased from 43.6% to 7.2% on the first occasion and from 46.7% to 12.5% on the second. Ventilation in the prone position can be an effective method for improving oxygenation in patients suffering from postoperative acute respiratory failure who are not responding to other ventilatory strategies.