Association of arterial blood pH at cannulation with 1-year survival
among VA-ECMO recipients: the three seven rule
Abstract
Objective We aimed to describe the clinical outcomes of
patients receiving veno-arterial extracorporeal membrane oxygenation
therapy considering clinical context and pH at cannulation.
Methods We reviewed all patients having received veno-arterial
extracorporeal membrane oxygenation therapy at a tertiary referral
center during the 2005-2020 period with 1-year complete follow up. Our
cohort was divided in three groups according to the pH level at
cannulation: pH<7 (group 1), pH 7-7.2 (group 2) and
pH>7.2 (group 3). Survival was analyzed using Kaplan–Meier
method. Association between pH group and survival was estimated using a
Cox model. Results Among the 951 patients in our database, 572
were included in 3 different groups according to their pH at
implantation: 60 patients in group 1, 115 in group 2 and 397 in group 3.
Main indications of mechanical support were refractory cardiogenic shock
(36%), post cardiotomy (28%), early graft failure (12%), refractory
cardiac arrest (11%). One-year survival rate was 13% in group 1, 36%
in group 2, 43% in group 3 respectively (p<0.001). Death
mainly occurred within the first month. The strong correlation between
pH and lactates led to propose a simple “three seven rule”:
pH<7 and lactate >7 was associated with
<7% survival. Conclusion Extracorporeal
veno-arterial membrane oxygenation should be considered with caution in
patients with pH<7. Lactates and pH level might be important
parameters to elaborate a new score to predict survival in this
population. The simplicity of the “three seven rule” can be very
relevant when facing emergency situations.