Sodium and potassium derangements in severe burns in the immediate post-burn period

Abstract

This was a descriptive prospective study that aimed to assess the incidence of sodium and potassium derangements seen in severe bum patients in the first five days postbum. The study group comprised all patients with severe bums admitted to the Bums Unit (BU), High Dependency Unit (HDU) and Intensive Care Unit (lCU) of Kenyatta National Hospital (KNH) within 24 hours of injury. 60 patients who met the inclusion criteria and consented to be enrolled were interviewed, examined and serial blood analysis for sodium and potassium undertaken daily for 5 consecutive days. 53 patients survived the five days of investigation, with 4 patients dying on days 6 and 7. Data on demographic characteristics, time of injury, time to admission, type of bum, percentage total body surface area bumt (%TBSA), predominant bum depth, amount of fluids given within 24 hours post-bum and presence of inhalation injury was collected. The mean rehydration factor (MRF) was calculated. The derangements observed were correlated with gender, age, mean rehydration factor, time delay to admission, type of bum and bum severity. Outcome at day 7 was assessed. This outcome was in terms of survival. The male: female ratio was 1:1.08. Open flame bums were most common (75%), followed by scalds (18%). Electrical and chemical bums were seen in 5% and 1.7% respectively. Scalds caused mainly partial-thickness bums in contrast to full-thickness burns seen following open flame injuries. Hypokalaemia and hyponatraemia were the predominant derangements seen. Hypokalaemia was noted in 33(62%) patients. Only 2 patients had episodes of hyperkalaemia. 45(85%) patients registered at least one episode ofhyponatraemia as compared to 8 (15%) who did not. 8 patients registered hypematraemia, all on

day l.Age and mean rehydration factor were the most predictive of the two main derangements, hypokalaemia and hyponatraemia. There were 11 deaths in week one, translating to a weekl mortality of 18%. While those with hypokalaemia and hyponatraemia registered more deaths than those without the derangements, this did not attain statistical significance (p-values of 0.1397 and 0.9090 respectively). Electrolyte derangements did not seem to significantly influence survival. Presence of inhalation injury and high %TBSA were however associated with poor outcome (p-values 0.0329 and 0.0034 respectively). It is very difficult to predict who will develop a certain derangement, but the young and those with low MRF should be closely scrutinised. Urea and Creatinine abnormalities were not seen in this study. The mean urea was 5.7 ± 2.6 rnmol/L, while Creatininewas 76.8 ± 23.4umol/L. There was no significant difference between those with hyponatraemia or hypokalaemia and those without in regard to urea and Creatinine.