Increased physiological dead space/tidal volume ratio during exercise in burned children

Exercise testing enables the simultaneous evaluation of the cardiovascular and respiratory systemsʹ ability to perform gas exchange. The physiological responses to exercise have not been previously reported in the postburn child. This investigation was designed to evaluate residual cardiopulmonary impairment in patients convalescing from severe burns. Spirometry, lung volumes and exercise stress testing were completed on 40 children with a mean time postburn injury of 2.6 ± 1.9 years and mean burn size of 44 ± 22 per cent TBSA. Respiratory variables studied during exercise included expired volume, tidal volume and respiratory rate, and physiological dead space/tidal volume (VD/VT) ratios. Stress testing revealed an increased VD/VT ratio consistent with uneven ventilation-perfusion relationships. The data indicate that patients who survive thermal injury may not regain normal cardiopulmonary homeostasis.