Sequential circulatory changes in the circumferentially burned limb

To assess the hemodynamic alterations in the circumferentially burned extremity, Doppler arterial examinations and Xenon-133 washout determinations of muscle blood flow (MBF) were obtained in 27 limbs. In this laboratory normal resting MBF was 2.82+/-0.86 cc/min/100 gm (mean +/- S.E.M., N=26) with no value less than 1.60 cc/min/100 gm. In 27 circumferentially burned limbs, the maximum decrement in MBF occurred by 36 hours following thermal injury. The lowest MBF value in the 11 extremities not requiring escharotomy was 1.50cc/min/100gm. Escharotomy was done in 16 extremities. Mean MBF immediately prior to escharotomy was 1.30+/-0.26cc/min/100gm and improved to 4.43+/-0.52cc/min/100gm following escharotomy (p less than 0.01). Correlation between MBF and Doppler examinations was present in 63% of all studies and in 88% of studies performed immediately before or after escharotomy. The diagnostic sensitivity of Doppler examination required audible recognition of abnormal velocity signals as well as absent velocity signals. Because the intial MBF determination or Doppler examination is not helpful in predicting which extremities will eventually require escharotomy, sequential studies should be done during the first 36-48 hours following thermal injury.