The effects of carbon dioxide management on plasma levels of fentanyl and sufentanil during hypothermic cardiopulmonary bypass.

This study examined the effects of carbon dioxide (CO2) management on the plasma levels of sufentanil and fentanyl during hypothermic cardiopulmonary bypass (HCPB). Thirty-two patients undergoing elective coronary artery bypass were divided into four groups: (I) fentanyl/alpha-stat; (II) fentanyl/pH-stat; (III) sufentanil/alpha-stat; and (IV) sufentanil/pH-stat. Fentanyl was administered intravenously at 50 micrograms/kg on induction with an additional 25 micrograms/kg just prior to sternotomy. Sufentanil was administered intravenously at 7 micrograms/kg on induction with an additional 3 micrograms/kg just prior to sternotomy. Samples were drawn at 5 (A) and 30 (B) minutes after institution of CPB (25 degrees C), and at 5 (C) minutes after discontinuation of CPB. Statistical comparisons were made between Group I and II, and Group III and IV at all three measurement points. The only significant (P < .01) finding was between Group III and IV at point B. The measured plasma levels of sufentanil were significantly lower under HCPB pH-stat management conditions. Until this observation is either confirmed or refuted, it would seem prudent for studies that report the plasma levels of sufentanil during HCPB to specify the type of CO2 management used.