Muscle tissue electrolytes in burned subjects

In a group of patients with burns covering at least 20 per cent of their body surface area (BSA), extracellular electrolytes and acid-base status and intracellular electrolytes and nitrogen (muscle needle biopsy) were measured both in the early phase (12–24 hours) and 7–14 days after burn injury.In the acute burn phase, extracellular electrolyte and acid-base disturbances are uncommon, while intracellular data shows increase of muscle sodium, decrease of muscle potassium and magnesium and normal muscle cell nitrogen.In the later burn phase, despite an adequate fluid, electrolyte and protein-calorie supply, the changes of electrolytes appear to be uncorrected; no decrease of muscle cell nitrogen is found. Our data could suggest that defects of the sodium-potassium pump in the cell membrane, which are thought to be the cause of intracellular electrolyte disturbances during the acute phase of burns, do not ameliorate with adequate fluid and protein-calorie intake; however, a persistent muscle potassium depletion is also consistent with a reduction of cell ‘capacity’ for potassium, possibly due to muscle protein catabolism, although muscle cell protein values do not show a significant reduction.