Background
Patients with tetralogy of Fallot experience changes in the dynamics of right ventricular outflow tract obstruction, or changes in systemic vascular resistance cause a decrease in the systemic arterial oxygen saturation. Dexmedetomidine use is not yet approved in pediatric patients, but its effects have been studied in pediatric patients during cardiac surgery, which showed a decrease in the incidence of arrhythmias after bypass. In this study, we postulate that dexmedetomidine may have potential benefits on the pulmonary vascular resistance, which may play a role in decreasing the incidence of tet spells during Fallot repair.
Patients and methods
This randomized controlled study was conducted in Cairo university pediatric hospitals, where patients were randomly allocated to two equal groups, 30 patients in each group between 6 months and 12 years of age. Patients were allocated to two groups to receive two different anesthesia maintenance regimens: group 1 (the ketamine group, =30) received isoflurane 0–1% together with ketamine infusion 1 mg/kg/h, and group 2 (the dexmedetomidine group, =30) received isoflurane 0–1% together with dexmedetomidine 0.25 μg/kg/h. Mean arterial pressure, heart rate, and oxygen saturation were recorded. Arterial blood gases, glucose and lactate levels, and number of tet spells, which is the primary outcome in our study, were evaluated.
Results
Our primary finding was the number of spells, which was 2 (range: 0–4) in the KET group compared with 0 (range: 0–2) in the DEX group (<0.001). Intraoperative heart rate decreased more in the DEX group than in the KET group at all times of measurement but with a significant difference at T2 and T3. Mean arterial pressure also decreased in the DEX group with a significant difference between the two groups at T1, T2, and T3.
Conclusion
Dexmedetomidine infusion as an adjuvant to anesthesia decreased the number of spells in the prebypass period significantly better than ketamine infusion in children undergoing Fallot repair.