以人工心肺分流模式探討不同抽血位置之Propofol濃度對血壓變化之影響

The Hypotensive Effects of Propofol at Different Sampling Sites in Cardiopulmonary Bypass Model

背景：本研究的目的在探討從動脈或上腔靜脈端抽取之血液樣本較適合預估propofol對血壓之影響。方法：選取八位接受心臟手術人工心肺分流術之病人，給予快速輸注充分稀釋之propofol溶液，並分別於輸注後0，0.5，1，1.5，2，5，10，20，30，40分鐘時，從分流之動脈端(Ca)及上腔靜脈端(Cv)抽取血液樣本，並同時記錄動脈血壓之變化。Propofol之濃度則事後以HPLC測量之。結果：動脈端濃度(Ca)從0.5至5分鐘之間明顯高於靜脈端濃度(Cv)，而動脈端濃度高峰期在第0.5分鐘時，接著快速下降，於約10分鐘時與靜脈端濃度曲線交叉，此後Cv便高於Ca。平均動脈血壓於輸注後1至20分鐘內明顯下降，而動脈血壓與上腔靜脈端濃度的改變在藥物分布期（0至5分鐘）相關性最強。結論：在人工心肺分流模式之下，快速輸注propofol，會產生相當明顯的動靜脈濃度差，尤其於藥物分布期時，其產生的血壓降低反應，以上腔靜脈端濃度來預測較佳。

Background: Although propofol has been widely used the uncertainties about its pharmacokinetics and pharmacodynamics are still in existence especially on acute infusion model. This study was designed to observe the changes of the arterial and superior vena cava blood concentrations of propofol during cardiopulmonary bypass and to see whichever site is more appropriate for pharmacodynamic studies of propofol. Methods: Eight patients undergoing cardiopulmonary bypass were infused rapidly with propofol. Samples were collected concurrently from bypass arterial side (Ca) and superior vena cava (Cv) side at 0, 0.5, 1, 1.5, 2, 5, 10, 20, 30, and 40 minutes after infusion and analyzed with high pressure liquid chromatography (HPLC). Arterial blood pressure was also recorded at the same time. Results: After administration, the concentration at Ca side was significantly higher than that at the corresponding Cv side from 0.5 to 5 min. The concentration at Ca side peaked at 0.5 min, then decreased rapidly and crossed the Cv curve at approximately 10 min. Thereafter Cv side concentration was slightly higher than that of Ca side. The mean arterial blood pressure decreased significantly from 1 to 20 min after injection. The change in Cv side was significantly consistent with the blood pressure change in the distribution phase (γ= 0.78, γ2 = 0.61 P < 0.001) (0 to 5 min). Conclusions: There was a significant arteriovenous concentration difference of propofol after a rapid infusion in the cardiopulmonary bypass model. The hypotensive effect of propofol in the distribution phase can be predicted better on Cv side.