EVALUATION OF TROPONIN-I AS AN INDICATOR OF CARDIAC DYSFUNCTION AFTERTHERMAL-INJURY

Background: Biochemical serum markers commonly used to assess human ca rdiac injury (creatinine phosphokinase, creatine phosphokinase-MB) hav e been shown to have diminished specificity for detection of cardiac i njury in the setting of burn-related soft-tissue and skeletal muscle i njury. Laboratory studies have demonstrated that severe cutaneous ther mal injury is associated with cardiac contractile dysfunction and a co rresponding elevation in serum cardiac troponin-I (cTn-I) in several s pecies. Methods: Twenty-three patients admitted to a tertiary care bur n referral center were evaluated. Patients were monitored with pulmona ry artery catheters, and creatinine phosphokinase, creatine phosphokin ase-MB, and cTn-I levels were determined for 24 hours. Using a databas e, 6,722 burn patients were reviewed to determine the incidence of pre existing cardiac disease and postburn cardiac complications. Results: All patients had persistent sinus tachycardia (>115 beats per minute) without obvious electrical anomalies. All patients centrally monitored with a pulmonary artery catheter (n = 20) maintained a cardiac index of greater than 3.0 L.min(-1).m(-2). cTn-I was present (>0./3 ng/mL) w ithin 3.0 hours and elevated (>0.55 ng/mL) at 24 hours for all burns o f more than 18% total body surface area. Historically, although only 5 % of all admissions manifest acute postburn cardiac complications, 94% of these patients presented with preexisting heart disease. Conclusio n: Severe thermal injury was associated with a mild elevation in serum troponin-I; however, this did not correlate with overt cardiac morbid ity or mortality. Postburn elevation of cTn-I suggested that a subtle degree of cardiac injury was present after a severe thermal injury des pite hyperdynamic cardiac function during resuscitation.