Hemodynamic Impact of Mechanical Ventilation in the Acute Respiratory Distress Syndrome

In Brief Recent data show that mortality from adult respiratory distress syndrome has declined over the years yet these patients continue to be a challenge for physicians. Mechanical ventilatory support is required to maintain oxygenation and support respiratory workload. However, experimental data, largely from animal studies, have shown that lung injury can be induced by mechanical ventilation and positive pressure ventilation may worsen the hemodynamic status of an already unstable patient. Some ventilatory strategies may be more deleterious than others. Using the evidence from experimental and clinical studies, a “lung protective” strategy of mechanical ventilation has been proposed combining low tidal volumes to limit stretch and adequate levels of positive end-expiratory pressure to prevent alveolar collapse. This strategy may also limit end organ damage and promote hemodynamic stability. Patients with the acute respiratory distress syndrome (ARDS) are among the most challenging group of patients, as they are both hypoxemic and often hemodynamically unstable. This paper reviews the physiologic impact of positive pressure ventilation with a focus on ventilatory strategies that minimize lung injury and hemodynamic compromise while maximizing oxygen delivery in ARDS.