Invited Commentary

Abstract

Dr Roncon-Albuquerque, Jr and colleagues [1Roncon-Albuquerque Jr., R. Ferreira-Coimbra J. Vilares-Morgado R. Figueiredo P. Paiva J.A. PaO2/FiO2 deterioration during stable extracorporeal membrane oxygenation associates with protracted recovery and increased mortality in severe acute respiratory distress syndrome.Ann Thorac Surg. 2016; 102: 1878-1885Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar] evaluated the effect of changes in Pao2/Fio2 (P/F) ratios between day 1 and day 7 after the institution of venous-venous (VV) extracorporeal membrane oxygenation (ECMO) for severe acute respiratory distress syndrome. They demonstrated a marked difference in patient outcomes for patients presenting an improving P/F ratio in1 week versus a decreasing P/F, eg, mortality was significantly decreased with an improving P/F ratio (22% versus 48%). Many factors can affect systemic blood oxygenation during VV ECMO. Among the most important are ECMO flow versus cardiac output and the residual lung function contribution. Other factors include recirculation (fraction of oxygenated circuit blood drained back to the circuit by the drainage cannula), body temperature, and oxygen extraction rate. The main message of this study is that the P/F ratio during the first week of an ECMO run can have significant prognostic value. However, it is likely that this is simply a representation of patients with less severe lung injury, leading to a more rapid recovery of native lung function. However, other important patient factors, such as absence of sepsis and therefore a less hyperdynamic patient (increased ratio between the blood oxygenated by the artificial lung and the patients' venous blood), may play a role in both the P/F ratio and final patient outcomes. Although the relatively low number of patients is a weakness of this study, the single-institution, well-standardized ventilation protocols before and after ECMO and consistent ECMO techniques (dual-cannula VV) and management add significant value to the findings. Once this is confirmed in a larger number of patients, the variation of P/F ratio in the first week after the institution of VV ECMO could be used as a simple prognostic marker that could aid not only in informing the patient’s family of his or her ultimate chance of recovery but also in the prediction of hospital resource use. Finally, it can also be used to stratify more equal groups for novel therapeutic trials in ECMO for acute respiratory distress syndrome. PaO2/FiO2 Deterioration During Stable Extracorporeal Membrane Oxygenation Associates With Protracted Recovery and Increased Mortality in Severe Acute Respiratory Distress SyndromeThe Annals of Thoracic SurgeryVol. 102Issue 6PreviewDuring extracorporeal membrane oxygenation (ECMO), arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2; PF ratio reflects native and artificial lung blood oxygenation). In this study we analyzed PF ratio during ECMO support and its association with clinical outcome. Full-Text PDF