Monitoring response to prone positioning

Purpose of review: The increasing use of prone position, in intubated patients with acute respiratory distress syndrome as well as in patients with acute hypoxemic respiratory failure receiving noninvasive respiratory support, mandates a better definition and monitoring of the response to the manoeuvre. This review will first discuss the definition of the response to prone positioning, which is still largely based on its effect on oxygenation. We will then address monitoring respiratory and hemodynamic responses to prone positioning in intubated patients. Finally, we will also discuss monitoring inspiratory effort in nonintubated patients with acute hypoxemic respiratory failure who breathe spontaneously and receive noninvasive respiratory support. Recent findings: The response to prone positioning should be enriched by data pertaining to lung protection beyond oxygenation. These include trans-pulmonary pressure, driving pressure, mechanical power, distribution of aeration and ventilation and assessment of potential for lung recruitment before the pronation. Summary: The implications of present findings are to: better select those patients who will benefit from proning in physiological terms, better indicate the timing of onset and end of the sessions, and strengthen the relationship between physiological response and patient outcome.