Clonidine as a First-Line Sedative Agent after Neonatal Cardiac Surgery: Retrospective Cohort Study

Objectives: To determine the cardiovascular tolerance of clonidine used as a first-line sedative after cardiac surgery in small infants. Design: Retrospective chart review. Setting: A tertiary and quaternary referral cardiac PICU. Patients: All infants younger than 2 months who received a clonidine infusion for sedation after cardiac surgery from October 2011 to July 2013. Interventions: None. Measurement and Main Results: Heart rate, blood pressure, central venous and left atrial pressure, vasoactive inotropic score, volume of fluid bolus, and lactate and central mixed venous saturation were assessed. Preinfusion values were compared with postinfusion values. Of 224 potentially eligible patients, only 23 infants met inclusion criteria, as most patients only received high doses of morphine and some received midazolam instead of clonidine. Clonidine administration was started at a median of 12 hours after surgery (Q1-Q3, 5-23), and infusion rate was 0.5-2 μg/kg/hr for a median duration of 30 hours (Q1-Q3, 12-54). Heart rate decreased (maximal mean decrease: 12% [149 beats/min (sd, 17) to 131 beats/min (sd, 17)]; p < 0.0001). Apart from a transient and limited drop in diastolic blood pressure of 13% (maximal mean decrease: from 42.8 mm Hg [sd, 5.9] to 37.1 mm Hg [sd, 4.0]; p = 0.018), all other cardiovascular variables were stable or improved. A contemporaneous cohort of patients who received midazolam, did so sooner after surgery, stayed longer in the PICU and showed less favorable hemodynamics. Conclusions: IV clonidine as sedative added to morphine in selected patients seems hemodynamically safe. The observed decrease in heart rate and diastolic blood pressure seems of minimal clinical importance as all other hemodynamic variables remained stable or improved. The safety of clonidine given early after cardiac surgery as alternative to midazolam merits further study.

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