INCREASED PHYSIOLOGICAL DEAD SPACE TIDAL VOLUME RATIO DURING EXERCISEIN BURNED CHILDREN

Exercise testing enables the simultaneous evaluation of the cardiovasc ular and respiratory systems' ability to perform gas exchange. The phy siological responses to exercise have not been previously reported in the postburn child. This investigation was designed to evaluate residu al cardiopulmonary impairment in patients convalescing from severe bur ns. Spirometry, lung volumes and exercise stress testing were complete d on 40 children with a mean lime postburn injury of 2.6+/-1.9 years a nd mean burn size of 44+/-22 per cent TBSA. Respiratory variables stud ied during exercise included expired volume, tidal volume and respirat ory rate, and physiological dead space/tidal volume (VD/VT) ratios. St ress testing revealed an increased VD/VT ratio consistent with uneven ventilation-perfusion relationships. The data indicate that patients w ho survive thermal injury may not regain normal cardiopulmonary homeos tasis.