Brooker R F, Butterworth J F, Kitzman D W, Berman J M, Kashtan H I, McKinley A C
Department of Anesthesia, Bowman Gray School of Medicine of Wake Forest University, Winston Salem, North Carolina 27157-1009, USA.
Anesthesiology. 1997 Apr;86(4):797-805. doi: 10.1097/00000542-199704000-00009.
Despite many advantages, spinal anesthesia often is followed by undesirable decreases in blood pressure, for which the ideal treatment remains controversial. Because spinal anesthesia-induced sympathectomy and management with a pure alpha-adrenergic agonist can separately lead to bradycardia, the authors hypothesized that epinephrine, a mixed alpha- and beta-adrenergic agonist, would more effectively restore arterial blood pressure and cardiac output after spinal anesthesia than phenylephrine, a pure alpha-adrenergic agonist.
Using a prospective, double-blind, randomized, cross-over study design, 13 patients received sequential infusions of epinephrine and phenylephrine to manage hypotension after hyperbaric tetracaine (10 mg) spinal anesthesia. Blood pressure, heart rate, and stroke volume (measured by Doppler echocardiography using the transmitral time-velocity integral) were recorded at baseline, 5 min after injection of tetracaine, and before and after management of hypotension with epinephrine and phenylephrine. Cardiac output was calculated by multiplying stroke volume x heart rate.
Five min after placement of a hyperbaric tetracaine spinal anesthesia, significant decrease in systolic (from 143 +/- 6 mmHg to 125 +/- 5 mmHg; P < 0.001), diastolic (from 81 +/- 3 to 71 +/- 3; P < 0.001), and mean (from 102 +/- 4 to 89 +/- 3; P < 0.001) arterial pressures occurred. Heart rate (75 +/- 4 beats/min to 76 +/- 4 beat/min; P = 0.9), stroke volume (115 +/- 17 to 113 +/- 13; P = 0.9), and cardiac output (8.0 +/- 1 l/m to 8.0 +/- 1l/m; P = 0.8) did not change significantly after spinal anesthesia. Phenylephrine was effective at restoring systolic blood pressure after spinal anesthesia (120 +/- 6 mmHg to 144 +/- 5 mmHg; P < 0.001) but was associated with a decrease in heart rate from 80 +/- 5 beats/min to 60 +/- 4 beats/min (P < 0.001) and in cardiac output from 8.6 +/- 0.7 l/m to 6.2 +/- 0.7 l/m (P < 0.003). Epinephrine was effective at restoring systolic blood pressure after spinal anesthesia (119 +/- 5 mmHg to 139 +/- 6 mmHg; P < 0.001) and was associated with an increase in stroke volume from 114 +/- 12 ml to 142 +/- 17 (P < 0.001) and cardiac output from 7.8 +/- 0.6 l/m to 10.8 +/- 1.1 l/m (P < 0.001).
Epinephrine management of tetracaine spinal-induced hypotension increases heart rate and cardiac output and restores systolic arterial pressure but does not restore mean and diastolic blood pressure. Phenylephrine management of tetracaine spinal-induced hypotension decreases heart rate and cardiac output while restoring systolic, mean, and diastolic blood pressure.
尽管脊麻有诸多优点，但常伴有不良的血压下降情况，对此理想的治疗方法仍存在争议。由于脊麻引起的交感神经切除术以及使用单纯α - 肾上腺素能激动剂进行处理均可单独导致心动过缓，作者推测，作为α和β肾上腺素能混合激动剂的肾上腺素，相较于单纯α - 肾上腺素能激动剂去氧肾上腺素，在脊麻后能更有效地恢复动脉血压和心输出量。
采用前瞻性、双盲、随机、交叉研究设计，13例患者在接受高压布比卡因（10 mg）脊麻后，依次输注肾上腺素和去氧肾上腺素以处理低血压。在基线、注射布比卡因后5分钟以及用肾上腺素和去氧肾上腺素处理低血压之前和之后，记录血压、心率和每搏量（使用经二尖瓣时间 - 速度积分通过多普勒超声心动图测量）。心输出量通过每搏量×心率计算得出。
在实施高压布比卡因脊麻后5分钟，收缩压（从143±6 mmHg降至125±5 mmHg；P < 0.001）、舒张压（从81±3降至71±3；P < 0.001）和平均动脉压（从102±4降至89±3；P < 0.001）显著下降。脊麻后心率（从75±4次/分钟至76±4次/分钟；P = 0.9）、每搏量（从115±17至113±13；P = 0.9）和心输出量（从8.0±1 l/m至8.0±1 l/m；P = 0.8）无显著变化。去氧肾上腺素在脊麻后能有效恢复收缩压（从120±6 mmHg升至144±5 mmHg；P < 0.001），但与心率从80±5次/分钟降至60±4次/分钟（P < 0.001）以及心输出量从8.6±0.7 l/m降至6.2±0.7 l/m（P < 0.003）相关。肾上腺素在脊麻后能有效恢复收缩压（从119±5 mmHg升至139±6 mmHg；P < 0.001），并与每搏量从114±12 ml增至142±17（P < 0.001）以及心输出量从7.8±0.6 l/m增至10.8±1.1 l/m（P < 0.001）相关。
肾上腺素处理布比卡因脊麻引起的低血压可增加心率和心输出量，并恢复收缩动脉压，但不能恢复平均和舒张压。去氧肾上腺素处理布比卡因脊麻引起的低血压会降低心率和心输出量，同时恢复收缩压、平均动脉压和舒张压。
