NONINVASIVE CARDIAC INDEX MONITORING IN GUNSHOT WOUND VICTIMS

Objective: To evaluate a bioimpedance device for the noninvasive measu rement of cardiac index (CI) against standard thermodilution measureme nts in patients with gunshot wounds. Methods: A prospective open-label performance evaluation was done using a convenience sample of gunshot wound victims initially treated in the resuscitation area of a high-v olume, urban ED. After initial resuscitation, patients had a flow-dire cted pulmonary artery catheter placed for thermodilution cardiac outpu t (GO) measurements. The CO measurements were made in triplicate and a veraged, Estimates of body surface area were used to convert these mea surements to CI estimates, Electrodes for bioimpedance measurements we re placed as soon as practical after ED arrival. Simultaneous measurem ents of CI using the bioimpedance device were made as clinically indic ated during each patient's hospital course. Results: There were 54 pat ients studied, with an overall mean (+/- SEM) age of 32 +/- 3 years, R evised Trauma Score of 6.7 +/- 0.4, and Injury Severity Scale score of 22 +/- 3. There were 42 survivors and 12 nonsurvivors. The CI as esti mated by bioimpedance correlated well with that measured by thermodilu tion (r = 0.79, p less than or equal to 0.02). The precision of the in vasive and noninvasive measurements was 1.1 L/min/m(2); the bias was - 0.011 L/min/m(2). In 24 patients with thoracic injuries requiring tube thoracostomy or thoracic surgery, the correlation of the 2 devices wa s r = 0.71 with precision and bias of 1.4 L/min/m(2) and -0.018 L/min/ m(2), respectively. Conclusions: Cardiac index can be noninvasively es timated in acutely injured patients with gunshot wounds using a bioimp edance device, Further study of bioimpedance measurements as a guide t o volume therapy is warranted.