Why Prone? Why Now? Improving Outcomes for ARDS Patients

Abstract

The latest evidence I have seen is that proning more than 16 to 18 hours/day showed benefits. Was the 12-hour mark a new change?The current evidence suggests that patients should remain in the prone position for most of the day (>16 h), if tolerated. Derecruitment of the lungs can occur when the patient is turned supine because of an increase in ventral-dorsal pleural pressure on the lungs. The greater than 12-hour mark is the recommendation from the American Thoracic Society/Society of Critical Care Medicine guidelines for patients with moderate to severe adult respiratory distress syndrome (ARDS) who are receiving mechanical ventilation. If no improvement is seen on initial prone positioning, consider a consecutive 48-hour trial, then stop if no improvement. Evidence of improvement includes fraction of inspired oxygen (Fio2) reduced by 0.10 or a 30-point increase in Pao2/Fio2 ratio. Discontinue proning if instability occurs or if the Pao2/Fio2 ratio is greater than 150 mm Hg and the Fio2 is less than 0.60.How do you determine whether prone positioning is best versus extracorporeal membrane oxygenation (ECMO)?Consider ECMO only after routine treatment strategies have failed, including the following:Are standards to place patients in the prone position quickly or within so many hours of diagnosis of ARDS?The time from lung injury to prone positioning should be less than 48 hours. Begin as soon as possible, if conventional ventilation is not meeting goals.How do you deal with hemodynamic instability during the 10 to 15 minutes after proning?For cardiovascular instability, adjust vasopressor dosage temporarily and then titrate back down as appropriate. For oxygen, repeat the hyperoxygenation until patients adjust. The body’s oxygen demand increases during a turn, so providing greater support may be enough to overcome the increase in demand. For life-threatening arrhythmias, return patients to the supine position immediately.