Objective: Infants are potentially more susceptible to cell death mediated via glutamate excitotoxicity attributed to cardiopulmonary bypass. We hypothesized that ketamine, via N-methyl D-aspartate receptor blockade and anti-inflammatory effects, would reduce central nervous system injury during cardiopulmonary bypass.
Methods: We randomized 24 infants, without chromosomal abnormalities, to receive ketamine (2 mg/kg, n = 13) or placebo (saline, n = 11) before cardiopulmonary bypass for repair of ventricular septal defects. Plasma markers of inflammation and central nervous system injury were compared at the end of surgery, and 6, 24, and 48 hrs after surgery. Magnetic resonance imaging and spectroscopy before cardiopulmonary bypass and at the time of hospital discharge were performed in a subset of cases and controls (n = 5 in each group). Cerebral hemodynamics were monitored postoperatively using near-infrared spectroscopy, and neurodevelopmental outcomes were assessed using Bayley Scales of Infant Development-II before and 2-3 wks after surgery.
Results: Statistically significant differences were noted in preoperative inspired oxygen levels, intraoperative cooling and postoperative temperature, respiratory rate, platelet count, and bicarbonate levels. The peak concentration of C-reactive protein was lower in cases compared to controls at 24 hrs (p = .048) and 48 hrs (p = .001). No significant differences were noted in the expression of various cytokines, chemokines, S100, and neuron-specific enolase between the cases and controls. Magnetic resonance imaging with spectroscopy studies showed that ketamine administration led to a significant decrease in choline and glutamate plus glutamine/creatine in frontal white matter. No statistically significant differences occurred between pre- and postoperative Bayley Scales of Infant Development-II scores.
Conclusions: We did not find any evidence for neuroprotection or neurotoxicity in our pilot study. A large, adequately powered randomized control trial is needed to discern the central nervous system effect of ketamine on the developing brain. brain.
Trial registration: The trial is registered at www.ClinicalTrials.gov, NCT00556361.