Impact of preoperative hyponatraemia on paediatric perioperative mortality


Prior to this no study had examined the relationship between preoperative hyponatraemia and paediatric perioperative complications. Their primary objective was to determine if preoperative hyponatraemia is predictive of patient morbidity and mortality. This is a retrospective analysis of children undergoing surgery in 2014 and 2015. The data of patients who underwent surgery were reviewed to determine if a serum sodium within 30 days of surgery was available.  A normal sodium was defined as 136-145mEq L-1, hyponatraemia was defined as mild (131-135mEq L-1) or severe (<130mEq L-1). Primary outcome was 30-day all-cause mortality.  Secondary outcomes were postoperative seizure within 30 days and prolonged length of stay.  35,291 patients were included in the study.  1 in 7 had hyponatraemia. There were 432 (0.8%) deaths at 30 days.  Compared with patients with a normal sodium those with any hyponatraemia had an increased odds ratio for 30-day mortality of 3.85.  Those with mild and severe hyponatraemia had increased rates of death even when adjusting for co-morbidity and procedural complexity.  Preoperative hyponatraemia did not have a consistent effect on mortality on patients with an ASA 2 and patients aged 13 months to 10 years. The association between hyponatraemia and mortality persisted even with the exclusion of premature infants who made up 48.8% of deaths.  There was a statistically significant association between severe preoperative hyponatraemia and postoperative seizures and prolonged length of stay.

Take Home Message

This study draws on a large data base of cases with very detailed information available for each patient and for that reason it provides some valuable information.  They claim that there is a 285% increased risk of mortality, after adjusting for co-morbidities, in patients with hyponatraemia and increased risk of seizures and length of stay in hospital.  Unlike adults this increased risk only seems to be associated with certain subsets including patients with an ASA of 3 or higher and in neonates and those aged over 10 years.  It is difficult to tell if the hyponatraemia is the cause of the increased morbidity and mortality or an indicator of how sick the patient was to begin with.  Although we do know that hyponatraemia is a particular worry in paediatric patients due to the risk of cerebral oedema and intracranial hypertension.  This study is of limited value due to it being retrospective therefore the reason for preoperative bloods being taken is unknown.  Also the data set used does not include a cause of death. I think there is sufficient information to justify correcting sodium in elective cases when appropriate and to encourage a prospective trial to study this further.

Reviewed by : Dr Roisin Nee