In the acute respiratory distress syndrome (ARDS), positive end-expiratory pressure (PEEP) may decrease ventilator-induced lung injury by keeping lung regions open that otherwise would be collapsed. Since the effects of PEEP probably depend on the recruitability of lung tissue, we conducted a study to examine the relationship between the percentage of potentially recruitable lung, as indicated by computed tomography (CT), and the clinical and physiological effects of PEEP.

This report summarizes current physiological and technical knowledge on esophageal pressure (Pes) measurements in patients receiving mechanical ventilation. The respiratory changes in Pes are representative of changes in pleural pressure. The difference between airway pressure (Paw) and Pes is a valid estimate of transpulmonary pressure. Pes helps determine what fraction of Paw is applied to overcome lung and chest wall elastance. Pes is usually measured via a catheter with an air-filled thin-walled latex balloon inserted nasally or orally. To validate Pes measurement, a dynamic occlusion test measures the ratio of change in Pes to change in Paw during inspiratory efforts against a closed airway. A ratio close to unity indicates that the system provides a valid measurement. Provided transpulmonary pressure is the lung-distending pressure, and that chest wall elastance may vary among individuals, a physiologically based ventilator strategy should take the transpulmonary pressure into account. For monitoring purposes, clinicians rely mostly on Paw and flow waveforms. However, these measurements may mask profound patient–ventilator asynchrony and do not allow respiratory muscle effort assessment. Pes also permits the measurement of transmural vascular pressures during both passive and active breathing. Pes measurements have enhanced our understanding of the pathophysiology of acute lung injury, patient–ventilator interaction, and weaning failure. The use of Pes for positive end-expiratory pressure titration may help improve oxygenation and compliance. Pes measurements make it feasible to individualize the level of muscle effort during mechanical ventilation and weaning. The time is now right to apply the knowledge obtained with Pes to improve the management of critically ill and ventilator-dependent patients.

To comprehensively assess published peer-reviewed studies related to extracorporeal membrane oxygenation (ECMO), focusing on outcomes and complications of ECMO in adult patients. Systematic review and meta-analysis. MEDLINE/PubMed was searched for articles on complications and mortality occurring during or after ECMO. Included studies had more than 100 patients receiving ECMO and reported in detail fatal or nonfatal complications occurring during or after ECMO. Primary outcome was mortality at the longest follow-up available; secondary outcomes were fatal and non-fatal complications. Twelve studies were included (1763 patients), mostly reporting on venoarterial ECMO. Criteria for applying ECMO were variable, but usually comprised acute respiratory failure, cardiogenic shock or both. After a median follow-up of 30 days (1st-3rd quartile, 30-68 days), overall mortality was 54% (95% CI, 47%-61%), with 45% (95% CI, 42%-48%) of fatal events occurring during ECMO and 13% (95% CI, 11%-15%) after it. The most common complications associated with ECMO were: renal failure requiring continuous venovenous haemofiltration (occurring in 52%), bacterial pneumonia (33%), any bleeding (33%), oxygenator dysfunction requiring replacement (29%), sepsis (26%), haemolysis (18%), liver dysfunction (16%), leg ischaemia (10%), venous thrombosis (10%), central nervous system complications (8%), gastrointestinal bleeding (7%), aspiration pneumonia (5%), and disseminated intravascular coagulation (5%). Even with conditions usually associated with a high chance of death, almost 50% of patients receiving ECMO survive up to discharge. Complications are frequent and most often comprise renal failure, pneumonia or sepsis, and bleeding.