Aerobic fitness is disproportionately low in adult burn survivors years after injury

Abstract

Objective A maximal aerobic capacity below the 20th percentile is associated with an increased risk of all-cause mortality.1 Adult burn survivors have a lower aerobic capacity compared to non-burned adults when evaluated 38±23 days post-injury.2 However, it is unknown if burn survivors with well-healed skin grafts (i.e., multiple years post injury), also have low aerobic capacity. This project tested the hypothesis that aerobic fitness, as measured by maximal aerobic capacity (VO2max), is reduced in well-healed adult burn survivors when compared to normative values from non-burned individuals.

Methods Twenty-five burn survivors (36 ± 12 years old; 13 females) with well-healed split thickness grafts (median: 16 years post-injury, range: 1 to 51 years) covering at least 17% of their body surface area (mean: 40±16%; range: 17 to 75%) performed a graded cycle ergometry exercise test to volitional fatigue. Expired gases and minute ventilation were measured via a metabolic cart for the determination of VO2max. Each subject’s VO2max was compared with sex- and age-matched normative values from population data published by the American College of Sports Medicine (ACSM), the American Heart Association (AHA), and recent epidemiological data.3

Results Subjects had a VO2max of 29.4 ± 10.1 ml O2/kg body mass/min (median: 27.5; range: 15.9 to 53.3). Using ACSM normative values, mean VO2max of the subjects was in the lower 24th percentile (median: 10th percentile). 88% of the subjects had a VO2max below AHA age-adjusted normative values. Similarly 20 of the 25 subjects had a VO2max in the lower 25% percentile of recent epidemiological data.

Conclusions Relative to non-grafted subjects, 80–88% of the evaluated skin graft subjects had a very low aerobic capacity. Based upon these findings, adult burn survivors are disproportionally unfit relative to the general U.S. population, and this puts them at an increased risk of all-cause mortality.