Differences in Resuscitation in Morbidly Obese Burn Patients May Contribute to High Mortality

Abstract

Objective The rising number of obese patients poses new challenges for burn care. These may include adjustments in calculations of burn size, resuscitation, ventilator wean, nutritional goals as well as challenges in mobilization. We have focused this observational study on resuscitation in the obese patient population in the first 48 hours after burn injury. Prior trauma studies suggest a prolonged time to reach end points of resuscitation in the obese compared to non-obese injured patients. We hypothesize that obese patients have worse outcomes after thermal injury and that differences in the response to resuscitation contribute to this disparity. Methods We retrospectively analyzed data prospectively collected in a multi-center trial to compare resuscitation and outcomes in patients stratified by NIH/WHO BMI classification (BMI: normal weight 18.5-24.9, overweight 25-29.9, Obese 30-39.9, morbidly obese ≥40). Due to distribution of body habitus in the obese, total burn size was recalculated for all patients using the method proposed by Neaman and compared to Lund-Browder estimates. We analyzed patients by BMI class for fluids administered and end points of resuscitation at 24 and 48 hours. Multivariate analysis was used to compare morbidity and mortality across BMI groups. Results We identified 296 adult patients with a mean TBSA of 41%. Patient and injury characteristics were similar across BMI categories. There were no significant differences in burn size calculations using Neaman vs. Lund-Browder formulas. Although resuscitation volumes exceeded the predicted formula in all BMI categories, higher BMI was associated with less fluid administered per actual body weight (p=0.001). Base deficit on admission was highest in the morbidly obese group at 24 and 48 hours. Furthermore, these patients did not correct their metabolic acidosis as well as lower BMI groups (p-values 0.04 and 0.03). Complications and morbidities across BMI groups were similar, although examination of organ failure scores indicated more severe organ dysfunction in the morbidly obese group. Compared to normal weight patients, being morbidly obese was an independent risk factor for death (OR = 10.1; CI 1.94-52.5, p= 0.006). Conclusions Morbidly obese patients with severe burns tend to receive closer to predicted fluid resuscitation volumes for their actual weight. However, this patient group has persistent metabolic acidosis during the resuscitation phase and is at-risk of developing more severe multiple organ failure. These factors may contribute to higher mortality risk in the morbidly obese burn patient.

The obesity factor in critical illness

“…79 Similar findings were also reported in morbidly obese patients with severe burns. 73 Other investigations concentrated on examining the specific impact of abdominal obesity on organ failure. 61,80 The study of Paolini et al 61 showed that visceral adiposity was associated with intra-abdominal hypertension and higher occurrence of kidney failure.…”

A quantitative assessment of variations in the palm surface area as a percentage of total body surface area within the general population

“…Existing studies have shown the errors in the LBC and RN approaches. As a larger percentage of the population qualifies as obese, these tools become more unreliable (Rae et al, 2013;Neaman et al, 2011;Berry et al, 2001;Livingston and Lee, 2001). An underestimation of the TBSA is likely with obese patients and higher body mass index (BMI).…”

The clinical study of incidence and role of co-morbid conditions in management and outcome of burns patients

“…6 296 adult patients with mean TBSA of 41% were taken up for study stated that being morbidly obese was an independent risk factor for death. Obese patients suffered persistent metabolic acidosis during resuscitation with high risk of multiple organ failure.…”