Hynson J M, Sessler D I, Moayeri A, Katz J A
Department of Anesthesia, University of California, San Francisco.
Anesthesiology. 1994 Dec;81(6):1411-21. doi: 10.1097/00000542-199412000-00016.
A decrease in radial artery blood pressure relative to central arterial blood pressure is commonly associated with the rewarming phase of cardiopulmonary bypass. Decreased hand vascular resistance has been suggested as a possible mechanism. Although decreased blood viscosity due to hemodilution may contribute to decreased hand vascular resistance, thermoregulatory vascular responses to core hyperthermia also may be important.
Seven healthy volunteers were studied. Volunteers first were cooled until thermoregulatory vasoconstriction was evident. Next, each was warmed until intense sweating developed. After a cool-down period, general anesthesia was induced with propofol and N2O. Femoral artery pressure (a surrogate for central arterial pressure) and radial artery and oscillometric (brachial artery) pressures were compared during each of six defined thermoregulatory and anesthetic study conditions. To determine the effect of hand vascular resistance on blood pressure differences, measurements were compared before and after occlusion of hand blood flow. Upper-extremity blood flow was evaluated by forearm and fingertip plethysmography and laser Doppler flowmetry.
Forearm, fingertip, and cutaneous blood flow increased significantly during warming and were maximal during intense sweating. During thermoregulatory vasoconstriction, femoral, radial, and oscillometric mean blood pressures were similar. In contrast, radial artery mean pressure was 5 +/- 1 mmHg less than femoral artery mean pressure and 12 +/- 8 mmHg less than oscillometric mean pressure during intense sweating. Hand compression reduced these differences. The contour of the radial artery pressure waveform was dramatically altered by thermoregulatory and anesthetic conditions. Radial artery systolic pressure exceeded both femoral artery and oscillometric systolic pressures during vasoconstriction but was less than these during intense sweating. Hand compression reestablished the exaggerated radial artery systolic pressure during all study conditions.
Thermoregulatory and anesthetic-induced alterations in upper-extremity blood flow substantially influence the relations among femoral artery, radial artery, and oscillometric blood pressure measurements.
桡动脉血压相对于中心动脉血压的降低通常与心肺转流的复温阶段相关。手部血管阻力降低被认为是一种可能的机制。尽管血液稀释导致的血液粘度降低可能有助于降低手部血管阻力，但对核心体温过高的体温调节性血管反应也可能很重要。
对7名健康志愿者进行了研究。志愿者首先被冷却，直到体温调节性血管收缩明显。接下来，每个人都被加热，直到大量出汗。在冷却期后，用丙泊酚和笑气诱导全身麻醉。在六个定义的体温调节和麻醉研究条件下，比较股动脉压（中心动脉压的替代指标）与桡动脉压和示波法（肱动脉）压。为了确定手部血管阻力对血压差异的影响，在阻断手部血流前后比较测量值。通过前臂和指尖体积描记法以及激光多普勒血流仪评估上肢血流。
在加热过程中，前臂、指尖和皮肤血流显著增加，在大量出汗时达到最大值。在体温调节性血管收缩期间，股动脉、桡动脉和示波法平均血压相似。相比之下，在大量出汗期间，桡动脉平均压比股动脉平均压低5±1 mmHg，比示波法平均压低12±8 mmHg。手部压迫减少了这些差异。桡动脉压力波形的轮廓因体温调节和麻醉条件而显著改变。在血管收缩期间，桡动脉收缩压超过股动脉和示波法收缩压，但在大量出汗时低于这些值。在所有研究条件下，手部压迫恢复了桡动脉收缩压的夸大情况。
体温调节和麻醉引起的上肢血流改变显著影响股动脉、桡动脉和示波法血压测量之间的关系。
