The impact of patient weight on burn resuscitation

Abstract

Background: Optimal fluid resuscitation of burn patients with burns greater than 20% total body surface area is critical to prevent burn shock during the initial 24 hours to 48 hours postburn. Currently, most resuscitation formulas incorporate the patient's weight when estimating 24-hour fluid requirements. The objective of this study was to determine the impact of weight on fluid resuscitation requirements and outcomes during the initial 24 hours after admission.

Methods: We performed a retrospective review of patients admitted to our burn intensive care unit from December 2007 to April 2013, resuscitated with a computerized decision support system. We classified patients into body mass index (BMI) categories of underweight (BMI: <18.5), normal (BMI: 18.5-24.9), overweight (BMI: 25.0-29.9), or obese (BMI: >30.0). We also calculated the percent difference from ideal body weight (IBW) and compared 24-hour fluid volumes received.

Results: Patients with missing weight and/or height values were excluded from the study, resulting in a final cohort of 161 patients for analysis. Mean total body surface area was 42 ± 20% with a full thickness burn of 18 ± 23%. Mean age, weight, and height were 47 ± 19 years, 83 ± 19 kg, and 68 ± 4 inches, respectively. IBW for this cohort was 68 ± 11 kg with a BMI of 28 ± 6. Univariate analysis showed significant differences in 24-hour resuscitation volumes (mL/kg) between normal and obese patients (p < 0.05). Further analysis revealed that increasing percent difference from IBW was associated with lower fluid volumes. Although obesity was not associated with inhalation injury or renal replacement therapy, it was correlated to an increased risk for mortality (p < 0.05).

Conclusion: This analysis showed that increasing weight was associated with lower fluid resuscitation volume requirements and a higher mortality rate, despite the low incidence of inhalation injury and renal replacement therapy in our obese patients. The use of actual body weight to drive resuscitation volumes may result in overresuscitation of obese patients, depending on the resuscitation formula. Further studies are needed to better explain the relationship between mortality and obesity in burn patients.

Level of evidence: Therapeutic/care management, level IV.