PaO2/FiO2Deterioration During Stable Extracorporeal Membrane Oxygenation Associates With Protracted Recovery and Increased Mortality in Severe Acute Respiratory Distress Syndrome.
BACKGROUND
During 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.


METHODS
This was a single-center observational study of adult patients (n = 81) undergoing veno-venous ECMO support for severe acute respiratory distress syndrome.


RESULTS
In 37 patients (46%) PF ratio decreased from ECMO-day 1 to ECMO-day 7 (PF ratio deterioration [PF-d]; -37 ± 6.1 mm Hg), whereas in 44 patients PF ratio improved (PF-i; 65 ± 10.8 mm Hg). PF-d group required prolonged ECMO (median 21 days [interquartile range (IQR)]:14-35 days] versus 13 days [IQR: 10-20 days]) and invasive mechanical ventilation (median 33 days [IQR: 24-52 days] versus 26 days [IQR: 22-34 days]), longer intensive care unit (median 44 days [IQR: 32-74 days] versus 30 days [IQR: 25-47 days]), and hospital (median 66 days [IQR: 39-95 days] versus 36 days [IQR: 28-54 days]) lengths of stay, with higher hospital mortality rates (48.7% versus 22.7%). ECMO oxygenation did not explain PF ratio variation that remained stable in PF-d and decreased in PF-i (198 ± 12.7 mL/min versus 171 ± 8.8 mL/min). Pre-ECMO PF ratio, neuromuscular blockade, and prone position, as well as ventilatory variables did not differ between groups. The PF-d group was older (49 ± 2.1 years versus 41 ± 1.8 years) and presented lower Respiratory Extracorporeal Membrane Oxygenation Survival Prediction (RESP) scores (0.57 ± 0.63 versus 2.2 ± 0.52). With the use of logistic regression, PF ratio variation remained an independent predictor of hospital mortality after adjusting for age or RESP score.


CONCLUSIONS
In severe acute respiratory distress syndrome, PF ratio deterioration during stable ECMO associates with protracted recovery and increased mortality, not accounted for by patient baseline characteristics, acute respiratory distress syndrome severity, or pre-ECMO management.
Department of Emergency and Intensive Care Medicine, Centro Hospitalar S. João, Porto, Portugal; Department of Physiology and Cardiothoracic Surgery, Faculty of Medicine, University of Porto, Porto, Portugal. Electronic address: rra_jr@yahoo.com.
Roberto
R
Roncon-Albuquerque
Department of Internal Medicine, Centro Hospitalar S. João, Porto, Portugal.
João
J
Ferreira-Coimbra
Department of Physiology and Cardiothoracic Surgery, Faculty of Medicine, University of Porto, Porto, Portugal.
Rodrigo
R
Vilares-Morgado
Department of Infectious Diseases, Centro Hospitalar S. João, Porto, Portugal.
Paulo
P
Figueiredo
Department of Emergency and Intensive Care Medicine, Centro Hospitalar S. João, Porto, Portugal; Department of Medicine, Faculty of Medicine, University of Porto, Porto, Portugal.
José Artur
JA
Paiva
D000328:Adult; D001784:Blood Gas Analysis; D003422:Critical Care; D015199:Extracorporeal Membrane Oxygenation; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D020127:Recovery of Function / Q000502:physiology; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000097:blood* / Q000401:mortality / Q000628:therapy*; D015656:Respiratory Mechanics / Q000502:physiology; D016896:Treatment Outcome