The lactate:pyruvate ratio following open cardiac surgery in children.
OBJECTIVE
To explore the relationship between lactate:pyruvate ratio, hyperlactataemia, metabolic acidosis, and morbidity.


METHODS
Prospective observational study in the paediatric intensive care unit (PICU) of a university hospital.


METHODS
Ninety-seven children after open cardiac surgery. Most children (94%) fell into low-moderate operative risk categories; observed PICU mortality was 1%.


METHODS
Blood was sampled on admission for acid-base analysis, lactate, and pyruvate. Metabolic acidosis was defined as standard bicarbonate lower than 22 mmol/l, raised lactate as higher than 2 mmol/l, and raised lactate:pyruvate ratio as higher than 20.


RESULTS
Median cardiopulmonary bypass and aortic cross-clamp times were 80 and 46 min. Metabolic acidosis occurred in 74%, hyperlactataemia in 42%, and raised lactate:pyruvate ratio in 45% of children. In multivariate analysis lactate:pyruvate ratio increased by 6.4 in children receiving epinephrine infusion and by 0.4 per 10 min of aortic cross-clamp. Duration of inotropic support increased by 0.29 days, ventilatory support by 0.27 days, and PICU stay by 0.42 days, for each 1 mmol/l increase in lactate. Neither standard bicarbonate nor lactate:pyruvate ratio were independently associated with prolongation of PICU support.


CONCLUSIONS
Elevated lactate:pyruvate ratio was common in children with mild metabolic acidosis and low PICU mortality. Hyperlactataemia, but not elevated lactate:pyruvate ratio or metabolic acidosis, was associated with prolongation of PICU support. Routine measurement of lactate:pyruvate ratio is not warranted for children in low-moderate operative risk categories.
Hatherill
Mark
M
Division of Critical Care and Children's Heart Disease, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa. mark.hatherill@uct.ac.za.
Salie
Shamiel
S
Division of Critical Care and Children's Heart Disease, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa.
Waggie
Zainab
Z
Division of Critical Care and Children's Heart Disease, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa.
Lawrenson
John
J
Division of Critical Care and Children's Heart Disease, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa.
Hewitson
John
J
Division of Critical Care and Children's Heart Disease, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa.
Reynolds
Louis
L
Division of Critical Care and Children's Heart Disease, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa.
Argent
Andrew
A
Division of Critical Care and Children's Heart Disease, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa.
D000138:Acidosis / Q000097:blood*; D000293:Adolescent; D001639:Bicarbonates / Q000097:blood*; D006348:Cardiac Surgical Procedures / Q000706:statistics & numerical data*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D015278:Intensive Care Units, Pediatric; D007773:Lactates / Q000097:blood*; D016014:Linear Models; D011184:Postoperative Period; D011446:Prospective Studies; D011773:Pyruvates / Q000097:blood*
D001639:Bicarbonates; D007773:Lactates; D011773:Pyruvates