Many of the drugs we use have been extensively studied in adults but not in children. Such is the case with sodium nitroprusside (SNP). Based on the Best Pharmaceuticals for Children Act, the National Institute of Child Health and Human Development has worked to address this shortcoming in our understanding of drug behavior in children. (That study will be described in more detail elsewhere.) The study involved a 30 minutes blinded infusion, followed by open-label SNP to titrate mean arterial blood pressure to a target value. Dr. David R. Spielberg, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, and colleagues from throughout the United States summarized the results of this study in this month’s issue of Anesthesia & Analgesia in the article titled “Predictors of Arterial Blood Pressure Control During Deliberate Hypotension with Sodium Nitroprusside in Children.”
One hundred fifty-three patients between 3 months and just under 17 years of age were studied at 7 sites. On average there were 4 dose adjustments per hour. Blood pressure control was defined as the percent of time spent in within spent target MAP. Though SNP has rapid titratability, blood pressure control was obtained slightly less than half the time (45%). Large changes in infusion rate were associated with worse blood pressure control, thus suggesting that smaller changes in SNP infusion rates are better.
Children undergoing cerebral catheterization had much less precise blood pressure control (22%), as defined above, compared with patients undergoing spinal (49%) and craniofacial surgery (41%). Neither age nor degree of hypotension predicted blood pressure control. There was no evidence that frequently changing the SNP infusion rate was any different than rarely adjusting it. Tachycardia was observed in 7.9% in all study participants.
Though SNP rapidly reduces blood pressure, achieving precise control of blood pressure is difficult. Whether there is a difference between children and adults is not clear. Perhaps it is time to again look at computer-controlled closed-loop delivery of sodium nitroprusside.