Prevalence of severe hypokalaemia in patients with traumatic brain injury

IntroductionPatients with traumatic brain injury (TBI) are more vulnerable to develop hypokalaemia, we sought to investigate the prevalence, and the relationship between severe hypokalaemia and the mortality of traumatic brain injury patients.MethodsIsolated traumatic brain patients who had hypokalaemia (serum potassium <3.5 mmol/L) and age ≥ 14 yrs were recruited into the study between January 2008 and March 2013. Hypokalaemia was defined as potassium level in the blood <3.5 mmol/L during the hospitalisation, which was classified by severity: mild (3.0 mmol/L ≤ K < 3.5 mmol/L), moderate (2.5 mmol/L ≤ K < 3.0 mmol/L) and severe (K < 2.5 mmol/L). Multivariable logistic regression was performed to find the impact of hypokalaemia on mortality.ResultsA total 375 cases were included in analysis. The peak incidence of severe hypokalaemia occurred in the first 24–96 h. TBI patients with severe hypokalaemia had significantly higher serum sodium and lower serum phosphorus than those patients with mild or moderate hypokalaemia (p < 0.001). Compare to other groups, the severe hypokalaemia group had the worst outcome. Moreover, the patients (n = 15) who had severe hypokalaemia, hypernatraemia (Na > 160 mmol/L), and hypophosphataemia (P < 0.3 mmol/L) all died in hospital. Multiple logistic regression analysis resulted in decrease of GCS (OR = 1.27; 95% CI = 1.15–1.41; p < 0.001) and potassium (OR = 4.35; 95% CI = 2.04–9.26; p < 0.001) being associated with significant increased risk of mortality.ConclusionsThe peak incidence of severe hypokalaemia occurred in the first 24–96 h. TBI patients with severe hypokalaemia are more vulnerable to develop hypophosphataemia and hypernatraemia than patients with mild and moderate hypokalaemia. Severe hypokalaemia are the independent risk factors for mortality in TBI patients.