Comparison of measures of physiologic stress during treadmill exercise in a patient with 20% lower extremity burn injuries and healthy matched and nonmatched individuals

Patients with burn injuries are referred for rehabilitation within days after the injuries to encourage early ambulation and functional training. Many of these patients are hypermetabolic at rest. Metabolic demands of activity are added to the already hypermetabolic state and elevate total energy requirements and some physiologic measures. Reports on the physiologic stress imposed by therapeutic activities for patients with burn injuries are limited to low levels of metabolic demand (< or =2 metabolic equivalents METS]). The degree of stress imposed by functional activities such as ambulation (3 METS) and stair climbing (5 METS) is not known for adults with burn injuries. The purpose of this study was to report the clinical measures of myocardial and physiologic stress in a patient with 20% lower extremity total body surface area burns during an exercise challenge equivalent to stair climbing. Physiologic measures were assessed before and during a treadmill activity (5 METS) for a 40-year-old obese man 3 weeks after he had lower extremity burn injuries. These measures were compared with mean values for 62 healthy counterparts and 6 healthy subjects matched for age, gender, and fitness level. Heart rate, systolic blood pressure, rate pressure product, and the rating of perceived exertion for the patient with burn injuries were higher at baseline and during exercise than the mean values for the 62 healthy individuals and the 6 matched subjects. The steady state exercise values for heart rate, systolic blood pressure, rate pressure product, and rating of perceived exertion at 6 minutes were 189 beats per minute, 190 mm Hg, 3591, and 17, respectively, for the patient with burn injuries and were 111.3 beats per minute, 149 mm Hg, 1680, and 11.7, respectively, for the 6 matched subjects. Ventilation during exercise also increased for the patient with burn injuries more than for the matched subjects (3/4 vs 1/4). Pain experienced by the patient with burn injuries decreased with activity (9.8 vs 7.3 on a 15-cm scale). Treadmill walking produced near maximal responses for most physiologic measures for this patient who was hypermetabolic at rest. We provided normative data to assist therapists who work with patients with similar burn injuries.