Sodium nitroprusside metabolism in children during hypothermic cardiopulmonary bypass.
Ten children, aged 1-7 yr, presenting for repair of complex congenital heart lesions, were prospectively studied. A ketamine, halothane/isoflurane, and fentanyl anesthetic was used. After initiation of hypothermic cardiopulmonary bypass, sodium nitroprusside (SNP) was titrated as necessary to maintain a target mean arterial blood pressure of 35-60 mm Hg. Blood samples drawn immediately prior to starting SNP infusion, every 15 min during infusion, and at 1, 4, and 24 h postinfusion were analyzed for whole blood cyanide (CN-) and serum thiocyanate (SCN-). Blood gas analysis was performed every 30 min during SNP infusion. A maximum CN- level > or = 1.0 micrograms/mL was observed in two children; four others had maximum CN- levels between 0.5 micrograms/mL and 1.0 micrograms/mL (normal, < 0.2 micrograms/mL). No child had a clinically important increase of SCN- subsequent to SNP infusion. There was substantial variability in observed CN- accumulation during SNP infusion. CN- levels during the first 60 min correlated with the average SNP rate of administration (P = 0.02). Cyanide levels rapidly decreased after termination of SNP infusion and were undetectable 4 h postinfusion. Despite the short-term increase of CN- level, no child showed biochemical signs of toxicity (acidosis or increased mixed venous oxygen tension).
D002315:Cardiopulmonary Bypass; D002648:Child; D002675:Child, Preschool; D003486:Cyanides / Q000097:blood*; D006330:Heart Defects, Congenital / Q000601:surgery*; D006801:Humans; D007036:Hypothermia, Induced; D007223:Infant; D009599:Nitroprusside / Q000378:metabolism*; D011446:Prospective Studies; D013861:Thiocyanates / Q000097:blood*
D003486:Cyanides; D013861:Thiocyanates; D009599:Nitroprusside