Here's a commonly used formula, the modified Parkland formula, for calculating fluid replacement in burn patients. Always base fluid replacement on the patient's response, especially in terms of the urine output. Urine output of 30 to 50 ml/hour is a sign of adequate renal perfusion in an adult. For small children, 1 to 2 ml/kg/hour is appropriate (Joffe, 2017).
Formula
Use 4 ml of lactated Ringer solution per kilogram of body weight per percentage of body surface area over 24 hours.
Example: For a 68-kg (150-lb) person with 27% body surface area burns, 4 ml × 68 kg × 27 = 7,344 ml over 24 hours. Give one-half of the total over the first 8 hours after the burn and the remainder over the next 16 hours.