Emergency War Surgery NATO Handbook: Part I: Types of Wounds and Injuries: Chapter III: Burn Injury
Urinary Output
United States Department of Defense
The most readily available clinical guide to the adequacy of resuscitation is the hourly urinary output, which should be maintained between 30-50 ml in patients weighing more than 30 kilograms and 1 ml/kg/hr in patients weighing less than 30 kilograms. In patients who require fluid resuscitation, an indwelling urethral catheter should be placed and the hourly urine output should be measured and recorded. Except possibly in patients with electric injury, oliguria in the first 48 hours postburn is rarely caused by acute renal failure and is treated by increasing fluid administration rather than by decreasing fluid administration or giving a diuretic.
Three categories of patients may require an osmotic diuretic: (1) those patients with significant electric injury in whom liberated hemochromogens increase the risk of acute renal failure, (2) those patients with associated crush or other injuries with extensive tissue death and large hemochromogen loads in the urine, and (3) those patients with large burns to whom one has given considerably more than the estimated fluid requirement but in whom oliguria persists. Osmotic diuretics, such as mannitol, will insure an adequate urinary output, but one must remember that this will occur at the expense of blood volume even in hypovolemic patients. Urinary output in patients who have received a diuretic is no longer a guide to the adequacy of resuscitation. Other diuretics, such as furosemide and ethacrynic acid, also have been used in burn patients.