Prevention of hyponatraemia with prophylactic oral sodium chloride in good grade aneurysmal subarachnoid haemorrhage

Objective: To assess the efficacy and safety of oral sodium chloride (Slow Sodium®) as hyponatraemia prophylaxis in patients with World Federation of Neurosurgical Societies (WFNS) Grade 1 and Grade 2 aneurysmal subarachnoid haemorrhage (aSAH). Methods: This prospective cohort study was conducted at Royal Victoria Hospital in Northern Ireland over two separate periods between 2015 and 2017, a total of 60 patients with aneurysmal subarachnoid haemorrhage were recruited. During Phase 1 (Jan 2015–Oct 2015), 32 patients were studied before hospital subarachnoid haemorrhage (SAH) protocol was modified. In Phase 2 (Jul 2016–Jan 2017), 28 patients received prophylactic oral sodium chloride (Slow Sodium®) in addition to standard SAH protocol. Primary outcomes were: incidence of hyponatraemia, length of hospital stay and Glasgow Outcome Scale (GOS) at a median of 4 months post-SAH; secondary outcome was the incidence of vasospasm. Results: Patients in Phase 2 demonstrated significantly lower incidence of hyponatraemia (p = 0.0006), shorter hospital stay (p < 0.05) and better long term neurological outcomes (p = 0.0069). Both patient groups had similar baseline characteristics. Hyponatraemia occurred in 24 patients (75%) and 8 patients (28.6%) enrolled in Phase 1 and Phase 2 respectively. Phase 2 patients had higher minimum serum sodium concentration (3.8, 95% Cl, 1.5–6.1; p < 0.002) and individuals who developed hyponatraemia had reduced severity. Individuals in phase 2 demonstrated better neurological outcomes and less severe deficits than phase 1 at clinic follow up, 27 patients (96.4%) had GOS 5 in phase 2 when there were only 22 patients (68.8%) in phase 1. Conclusion: Oral sodium chloride (Slow Sodium®) was found to be effective and safe as prophylactic treatment for hyponatraemia in WFNS Grade 1 and Grade 2 aneurysmal SAH patients. This led to a significant reduction in hyponatraemia incidence, shorter hospital stay and better long term neurological outcomes, although difference in incidence of vasospasm was not statistically significant