Duthie D J, Stevens J J, Doyle A R, Baddoo H H, Gupta S K, Muir K T, Kirkham A J
Department of Anaesthesia, Papworth Hospital, Cambridge, United Kingdom.
Anesth Analg. 1997 Apr;84(4):740-4. doi: 10.1097/00000539-199704000-00007.
We measured the apparent blood clearance and pulmonary extraction ratio of remifentanil in 10 adult patients undergoing elective myocardial revascularization for the first time with hypothermic cardiopulmonary bypass (CPB). Patients received continuous infusions of remifentanil 1.0, 1.5 or 2.0 microg x kg(-1) x min(-1). After surgery, remifentanil was infused at 1.0 microg x kg(-1) x min(-1) in all patients. Remifentanil concentrations were measured in pulmonary and radial artery blood by gas chromatography with high resolution mass spectrometry before and after CPB and 165 min (60 SD) after surgery. Cardiac output was measured by thermodilution at the time of blood sampling. The mean pulmonary extraction ratio of remifentanil was 5.7% (13.1% SD), which was not significantly different from zero. However, pulmonary extraction ratio was related inversely to the pulmonary artery hydrogen ion concentration and directly to the percent of nonionized form of the base in the pulmonary artery. Remifentanil concentrations in pulmonary and radial artery blood were related directly to infusion rate, but not to duration of infusion. There was no evidence of accumulation or sequestration. Mean apparent blood remifentanil clearance was 2.03 L/min (0.35 SD) and, in contrast to remifentanil pulmonary extraction ratio, was related directly to cardiac index and oxygen delivery. Increased tissue perfusion increased blood remifentanil clearance. We found predictable blood remifentanil levels with no evidence of accumulation or pulmonary extraction.
我们测量了10例首次接受择期心肌血运重建术并采用低温体外循环（CPB）的成年患者中瑞芬太尼的表观血清除率和肺摄取率。患者接受1.0、1.5或2.0微克·千克⁻¹·分钟⁻¹的瑞芬太尼持续输注。术后，所有患者均以1.0微克·千克⁻¹·分钟⁻¹的速度输注瑞芬太尼。在CPB前后以及术后165分钟（标准差60分钟），通过气相色谱-高分辨率质谱法测量肺和桡动脉血中的瑞芬太尼浓度。在采血时通过热稀释法测量心输出量。瑞芬太尼的平均肺摄取率为5.7%（标准差13.1%），与零无显著差异。然而，肺摄取率与肺动脉氢离子浓度呈负相关，与肺动脉中碱基非离子化形式的百分比呈正相关。肺和桡动脉血中的瑞芬太尼浓度与输注速率直接相关，但与输注持续时间无关。没有蓄积或潴留的证据。瑞芬太尼的平均表观血清除率为2. 03升/分钟（标准差0. 35），与瑞芬太尼肺摄取率不同，它与心脏指数和氧输送直接相关。组织灌注增加会提高血中瑞芬太尼清除率。我们发现瑞芬太尼血药浓度可预测，且没有蓄积或肺摄取的证据。
