Introduction: Hyponatraemia is the most common electrolytic disorder in clinical practice. We designed a protocol, based on the latest consensus statements and adapted to our Hospital, for the use of 3% hypertonic saline solution (HSS) in patients with hyponatraemia.
Material and methods: Unicentric observational study of a case series. We collected data from 14 adult patients with severe hyponatraemia (serum sodium [SNa] <125 mmol/l) and mild-moderate hyponatraemic encephalopathy (no signs of brain herniation) treated with an intravenous bolus of 250 ml of HSS over 30 minutes and reevaluated 6 hours later. Our goal was to raise 46 mmol/l as soon as possible, and 6-8 mmol/l in 24 hours with a limit of 12 mmol/l. The bolus was repeated if SNa raised <3 mmol/l.
Results: Median age (IQR) was 69.9 (64.578.1) years, and 62% were female. Baseline median SNa was 120 (114.3122.8) mmol/l. Median SNa 6 hours after the bolus was 124.4 (120.7128.3) mmol/l, a median raise of 5 (4.46.2) mmol/l (P<0.001). One patient required an additional bolus. Median SNa raise 24 hours after the bolus was 6 (3.98.2) mmol/l (P<0.01) in 9 patients; there was no significant change between 6 and 24 hours. Median rise per 100 ml of HSS was 2 (1.72.5) mmol/l after 6 hours and 2.4 (1.63.3) mmol/l after 24 hours. No patients required treatment for overcorrection nor had adverse outcomes. No significant changes were observed in serum potassium and creatinine.
Conclusions: Our data suggests that this protocol is safe and effective to reach the goals in the treatment of severe hyponatraemia with mild-moderate encephalopathy in the first 6 hours, without noticeable side effects or overcorrection. Patients at low risk of osmotic demyelination may receive another bolus to reach a higher SNa in 24 hours. Larger studies are required to confirm these results.