Serum lactate at 24 hours is associated with outcome in children requiring extracorporeal membrane oxygenation for pulmonary causes – a retrospective, observational study

Abstract

OBJECTIVES Extracorporeal membrane oxygenation (ECMO) has become an essential life-saving tool. Being resource-intensive, judicious use and optimising the outcomes of this precious resource is important. This retrospective, explanatory, observational study aimed to quantify associations between factors and outcome after pulmonary ECMO in children. METHODS This study included 39 consecutive ECMO runs in 38 children performed for pulmonary indications at our hospital from 2008 to 2018. Indications included acute respiratory distress syndrome, infection, drowning, meconium aspiration and pulmonary hypertension, among others. Depending on the need for haemodynamic support, 21 patients (53.8%) received veno-venous ECMO, while 18 (46.2%) received veno-arterial ECMO. We sought to compare the 11 non-survivors with the 27 survivors with respect to time-independent and time-dependent variables. Logistic regression models and Cox proportional hazards models were used. Threshold analysis was done using the “minimum p-value approach”. RESULTS 27/39 (69%) ECMO runs could be weaned; 27/38 (71%) patients were discharged. 20/27 (74%) survivors had unremarkable neurological status, six (22%) had mild findings (convulsions, muscular hypotony, neuropathy) and one (4%) had a hemi-syndrome at discharge. Univariate analyses showed a hazard ratio (HR) of 0.48 for log(pH) (95% confidence interval [CI] 0.22 to 1.02, p = 0.055) and an HR of 4.48 for log(lactate) (95% CI 1.92 to 10.48, p = 0.0005). Multivariate models showed an HR of 0.99 for log(pH) (95% CI 0.43 to 2.26, p = 0.98) and an HR of 4.44 for log(lactate) (95% CI 1.65 to 11.95, p = 0.003). Threshold analysis showed lactate >4.1 to be associated with mortality, with an HR of 32.7 (95% CI 4.8 to 221.7, p = 0.0002). This threshold should, however, be interpreted very cautiously. Evidence of an association between serum lactate at 24 hours and mortality was found (difference between survivors and non-survivors: −2.78, 95% CI −5.36 to −0.20, p = 0.037). CONCLUSIONS The results of ECMO for pulmonary indications are very good. Serum lactate may be an early prognostic indicator.

Keywords

• ECMO
• paediatric
• hypoxia
• outcomes
• temporary circulatory support