• E Bennett-Guerrero, J L Jimenez, W D White, E B D'Amico, B I Baldwin, and D A Schwinn.
• Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA.
• JAMA. 1996 Mar 6; 275 (9): 687-92.

ObjectiveTo test the hypothesis that triiodothyronine (T(3)) administration improves hemodynamic variables and decreases inotropic drug requirements in cardiac surgery patients.DesignProspective, randomized, double-blind, placebo-controlled trial.SettingTertiary care medical center.PatientsA total of 211 patients undergoing coronary artery surgery at high risk for requiring inotropic drug support.InterventionAt release of aortic cross-clamp, patients were randomized to an intravenous infusion of T(3) (0.8 microg/kg followed by 0.12 microg.kg(-1).h(-1) for 6 hours), dopamine (positive control, 5 microg.kg(-1).min(-1) for 6 hours) or placebo.Main Outcome MeasuresPerioperative hemodynamic variables, inotropic support requirements, and serum T(3) concentrations.ResultsMean+/-SEM free T(3) serum concentrations decreased significantly during cardiopulmonary bypass in all groups (from 0.0035+/-0.0001 nmol/L [0.23+/-0.01 ng/dL] to 0.001+/-0.0001 nmol/L [0.7+/- 0.00 ng/dL]; P=.001) and increased to 0.0133+/-0.0004 nmol/L [0.87+/-0.03 ng/dL] (twice normal range; P<.001) following initiation of intravenous T(3). Intravenous T(3) did not change hemodynamic variables or inotropic drug requirements; however, heart rate increased (P<.001), and a trend toward decreased use of inotropic agents was demonstrated in the dopamine group.ConclusionsTriiodothyronine administration prevents decreases in serum thyroid hormone concentrations associated with cardiopulmonary bypass. Intravenous T(3) does not have dramatic effects on hemodynamic variables in this setting as has been previously suggested. Although mild effects on myocardial performance may exist, we cannot recommend at this time the routine use of intravenous T(3) as an inotropic agent in patients undergoing coronary artery bypass graft surgery.

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