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Investigating Cardiac Metabolism in the Isolated Perfused Mouse Heart with Hyperpolarized [1-13C]Pyruvate and 13C/31P NMR Spectroscopy
Published on: April 21, 2023
The lactate:pyruvate ratio following open cardiac surgery in children
Mark Hatherill1, Shamiel Salie2, Zainab Waggie2
1Division 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.
Insights
Hyperlactataemia, not lactate:pyruvate ratio or metabolic acidosis, prolonged PICU stay in children post-cardiac surgery. Routine lactate:pyruvate ratio measurement is not recommended for low-risk pediatric patients.
Area of Science:
- Pediatric Intensive Care
- Cardiothoracic Surgery
- Metabolic Monitoring
Background:
- Metabolic acidosis and hyperlactataemia are common post-cardiac surgery in children.
- The lactate:pyruvate ratio is a potential marker for tissue hypoperfusion.
- Understanding these markers' impact on outcomes is crucial for pediatric intensive care.
Purpose of the Study:
- To investigate the association between lactate:pyruvate ratio, hyperlactataemia, metabolic acidosis, and morbidity in pediatric cardiac surgery patients.
- To determine if lactate:pyruvate ratio or metabolic acidosis predict prolonged intensive care unit stay.
Main Methods:
- Prospective observational study in a university hospital's pediatric intensive care unit (PICU).
- Enrolled 97 children undergoing open cardiac surgery, predominantly low-moderate risk.
- Measured acid-base status, lactate, and pyruvate on admission; defined metabolic acidosis, hyperlactataemia, and elevated lactate:pyruvate ratio.
Main Results:
- Metabolic acidosis (74%), hyperlactataemia (42%), and elevated lactate:pyruvate ratio (45%) were prevalent.
- Hyperlactataemia was independently associated with increased duration of inotropic support, ventilatory support, and PICU stay.
- Lactate:pyruvate ratio and standard bicarbonate were not independently associated with prolonged PICU support.
Conclusions:
- Hyperlactataemia, but not elevated lactate:pyruvate ratio or metabolic acidosis, correlated with longer PICU stays in this cohort.
- Routine lactate:pyruvate ratio measurement is not indicated for low-to-moderate risk pediatric cardiac surgery patients.
- Focusing on hyperlactataemia may be more clinically relevant for predicting prolonged PICU support in this population.
Objective:
To explore the relationship between lactate:pyruvate ratio, hyperlactataemia, metabolic acidosis, and morbidity.
Design And Setting:
Prospective observational study in the paediatric intensive care unit (PICU) of a university hospital.
Patients:
Ninety-seven children after open cardiac surgery. Most children (94%) fell into low-moderate operative risk categories; observed PICU mortality was 1%.
Interventions:
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.
Measurements And 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.
