Effect of nicardipine on vascular capacitance: Comparison with sodium nitroprusside during induced hypotension

The purpose of this study was to examine the effects of nicardipine and sodium nitroprusside (SNP) on vascular capacitance in the rat. In ten rats anesthetized with pentobarbital, mean arterial pressure was lowered to about 70 mmHg and subsequently 50 mmHg by intravenous infusion of nicardipine or SNP. Vascular capacitance was assessed before and during nicardipine- or SNP-induced hypotension by measuring the mean circulatory filling pressure (MCFP). MCFP was measured during a brief period of circulatory arrest produced by inflating a balloon inserted in the right atrium. MCFP was significantly decreased by SNP from 7.1 ±0.3 mmHg at control to 5.6 ± 0.4 mmHg and 4.4 ± 0.3 mmHg at mean arterial pressures of 70 mmHg and 50 mmHg, respectively. However, MCFP stayed at a similar level to that of the control during nicardipine-induced hypotension. These results suggest that nicardipine has a negligible influence on vascular capacitance during induced hypotension, whereas SNP has a potent vasodilating effect on the venous system as well as the arterial system.     

Skeletal muscle oxygen pressure fields during controlled hypotension with adenosine and sodium nitroprusside A comparative study in the rabbit

The MDO (Mehrdraht Dortmund Oberfläche) multiwire oxygen electrode was used for studies of oxygen pressure fields in eight rabbit skeletal muscle preparations during controlled hypotension with adenosine and sodium nitroprusside (SNP). Tissue oxygen histograms were constructed from 120 simple tissue oxygen pressures (P_tO₂) samples that were collected during 5 min. Statistical analysis between histograms was performed with the two-sample Kolmogorov-Smirnov test. Mean arterial blood pressure was reduced to 60 mmHg with both drugs, corresponding to a 42–43% reduction during the 25-min hypotension period. SNP-induced hypotension caused significant reduction of muscle oxygenization (compared to normotensive controls) in six of the animals, while this occurred on three occasions during adenosine administration. When comparing the histograms during hypotension, the tissue oxygenation during adenosine infusion was higher than during SNP in five and equal to SNP in three animals. Low tissue oxygen pressure values (0-0.6 kPa) were four times more frequent during SNP than during adenosine hypotension, although systemic arterial oxygen pressures were unaffected. We conclude that controlled hypotension with adenosine preserves tissue oxygen pressures better than hypotension induced by SNP.     

Changes in venous capacitance during prostaglandin E1-induced hypotension; Comparisons with trinitroglycerin

The purpose of this study was to examine the effects of prostaglandin E₁ (PGE₁) on venous capacitance during controlled hypotension. Trinitroglycerin (TNG) was used as a control agent. In rats anesthetized with ketamine, mean arterial pressure was lowered to 70mmHg and subsequently 50mmHg by intravenous infusion of PGE₁ or TNG. Venous capacitance was assessed before and during induced hypotension by measuring the mean circulatory filling pressure (MCFP). MCFP was measured after briefly arresting the circulation by inflating an indwelling balloon in the right atrium. MCFP was significantly decreased by PGE₁ from 7.9 ± 0.3 to 6.9 ± 0.3mmHg at mean arterial pressure of 70mmHg and to 6.9 ± 0.2mmHg at mean arterial pressure of 50mmHg. The decrease in MCFP by PGE₁ at mean arterial pressure of 70mmHg was not significantly different from TNG. However, the decrease in MCFP by PGE₁ at mean arterial pressure of 50mmHg was significantly less than that by TNG. The results suggest that the venous capacitance may be increased by PGE₁ to a similar degree with TNG at doses to produce a comparable level of moderate hypotension, but the increase in venous capacitance may be less in PGE₁ than TNG at doses to produce deep hypotension.(Liang J, Hoka S, Okamoto H, et al.: Changes in venous capacitance during prostaglandin E₁-induced hypotension; comparisons with trinitroglycerin. J Anesth 7: 303–307, 1993)     

前列腺素E1与硝普钠控制性降压对犬血流动力学影响的对比研究

对比研究了普鲁卡因复合麻醉下前列腺素Ｅ１（ＰＧＥ１）与硝普钠（ＳＮＰ）控制性降压时犬血流动力学变化。结果表明，ＳＮＰ降压组有显著的反射性心动过速和反跳性高血压，ＰＧＥ；降压组两者均无。ＰＧＥ１降压时心指数、肺动脉压等其它血流动力学参数亦比ＳＮＰ稳定，提示在保证心肌氧供求平衡及防止血管意外方面ＰＧＥ１降压优于ＳＮＰ。     

右美托咪定联合硝普钠控制性降压在腔内隔绝术中的应用

目的探讨右美托咪定联合硝普钠控制性降压在腔内隔绝术中应用的安全性和有效性。方法选择诊断为DebakeyⅢ型夹层动脉瘤拟行腔内隔绝术的患者40例,男32例,女8例,年龄27~79岁,ASAⅡ或Ⅲ级,随机分为硝普钠组(S组)和右美托咪定联合硝普钠组(SD组),每组20例。SD组全麻诱导前给予右美托咪定1μg/kg,15min内泵注完毕;S组给予等量的生理盐水,两组均在切皮时泵注硝普钠实施控制性降压。记录两组患者入手术室时(T0)、泵注硝普钠后5min(T1)、10min(T2)及停止泵注硝普钠后5 min(T3)、10 min(T4)的SBP、HR;记录达到目标血压(70~90mm Hg)所用的时间、硝普钠的平均用量及手术麻醉过程中不良反应的发生情况。结果与T0时比较,T1~T3时S组、T1~T4时SD组的SBP明显下降,T3时S组、T1~T4时SD组的HR明显减慢(P0.05)。T3、T4时SD组的SBP明显低于S组,T1~T4时的HR明显慢于S组(P0.05)。SD组达到目标血压所用的时间明显短于S组(P0.05),硝普钠的平均用量明显少于S组(P0.05);SD组心动过速和术后躁动的发生率明显低于S组(P0.05)。结论右美托咪定联合硝普钠用于腔内隔绝术中控制性降压更平稳快速、安全有效。     

硝普钠控制性降压对心率变异性的影响

目的　观察硝普钠控制性降压对心率变异性的影响。方法　ASAⅠ级鼻内窥镜手术病人 5 2例。降压前、降压稳定即刻、此后 10、30分钟、复压前、复压稳定即刻和此后 5分钟 ,记录LF/HF、LF、HF及TP。结果　降压稳定即刻的LF/HF较降压前增加 ,降压稳定后 10、30分钟LF/HF较降压稳定即刻降低 (P <0 0 5 )。复压稳定即刻LF/HF大于复压前 ,复压稳定后 5分钟LF/HF小于复压稳定即刻 ,HF大于复压稳定即刻 (P <0 0 5 )。结论　硝普钠控制性降压初期交感迷走神经张力的均衡性改变 ,交感神经张力的增高较迷走神经张力的增高幅度大。血压稳定后交感 迷走神经张力达到新的平衡。复压稳定后 5分钟迷走神经的张力进一步增高     

硝普钠-艾司洛尔用于神经外科控制性降压的临床研究

目的　研究硝普钠或硝普钠 艾司洛尔用于轻或中度颅内高压患者控制性降压对脑氧代谢和颅内压的影响。方法　 1 8例颅内压轻度增高的颅内肿瘤患者 ,在持续丙泊酚静脉麻醉 (目标血浓度 5 μg/ml)下行开颅手术。采用硝普钠或硝普钠 艾司洛尔控制性降压至动脉压 6 4～ 6 8/ 4 0～4 5mmHg,持续 1h。监测降压前后及降压期间颈内静脉血氧饱和度及动脉氧分压、颅内压、心率、血压变化。结果　在丙泊酚全身麻醉下硝普钠降压不引起颅内压增高 ,脑氧代谢良好。合并使用艾司洛尔 5 0 μg·kg 1 ·min 1 ,有助于维持较低的颅内压 ,并可减慢心率 ,防止硝普钠停药后反跳性高血压 ,硝普钠用量亦减少约 4 5 %。结论　硝普钠降压用于丙泊酚静脉麻醉的神经外科病人 ,脑氧代谢良好 ,联合使用硝普钠、艾司洛尔优于单纯使用硝普钠     

硝普钠控制性低血压对犬胃粘膜灌注的影响

目的　观察硝普钠控制性低血压对犬胃粘膜灌注的影响。方法　 1 6只健康杂种犬 ,随机分为对照组和控制性低血压组。基础麻醉后气管插管 ,经口置入胃张力计导管 ,股动、静脉置管 ,右颈内静脉放置Swan Ganz四腔漂浮导管。控制性低血压组静脉泵注 0 0 2 %硝普钠溶液进行控制性低血压 ,将MAP维持在 6 0mmHg 30min。监测降压期间血液动力学参数MAP、HR、CVP、肺动脉压 (MPAP)、肺毛细血管楔压 (PCWP)、心输出量 (CO)、每搏指数 (SVI)、体循环阻力指数 (SVRI)、肺循环阻力指数 (PVRI)、左室搏功指数 (LVSWI)、右室搏功指数 (RVSWI)、胃粘膜二氧化碳分压 (Pg CO2 )及胃粘膜与呼气末二氧化碳分压差 (Pg etCO2 )的变化。结果　与对照组相比 ,低血压组SVRI、PVRI显著下降 (P <0 0 5 ) ,LVSWI亦显著下降 (P <0 0 5 ) ;而CO、SVI、CVP、PCWP、RVSWI不变。在MAP 6 0mmHg的低血压水平 ,PgCO2 、Pg etCO2 分别由 4 7.4 5、9 0 7mmHg显著升高至 6 0 5 4、2 1 2 1mmHg(P <0 0 5 ) ,血压回升后上述指标均恢复正常。 结论　在保持充足血管内容量的条件下 ,硝普钠控制性低血压期间全身血管阻力显著下降 ,而心输出量不变。低血压期间胃粘膜灌注短暂受损 ,与血流重分布有关     

硝普钠控制性降压对血液动力学及脑氧平衡的影响

目的 研究硝普钠控制性降压对颅内手术病人血液动力学及脑氧供需平衡的影响。方法 择期颅内手术病人12例，用硝普钠使平均动脉压(MAP)降至50～65mmHg，并维持30min。降压前后，自桡动脉和颈内静脉球部取血进行血气分析和血糖测定，并以CO2复吸人法无创心排血量监舅仪(NiCO2)连续监测心排血量(CO)。结果 (1)降压期间，HR明显加快，CO先下降后又回升至降压前水平;颈静脉血氧饱和度无明显下降；(2)动-颈内静脉球部氧含量差、脑氧摄取率、动-颈内静脉糖含量差和脑葡萄糖摄率麻醉后均显著下降，降压及停降压后均进一步下降，仅脑氧摄取率降压后稍增加。结论 硝普钠控制性降压时心率增快，CO无明显变化，脑氧供需可维持平衡，但对葡萄糖的利用减少。     

Cardiovascular function during controlled hypotension induced by adenosine triphosphate or sodium nitroprusside in the anesthetized dog

The present study was undertaken to compare the hemodynamic effects of adenosine triphosphate (ATP) and sodium nitroprusside (NP) given in equieffective doses to induce hypotension during halothane anesthesia. Eight dogs, instrumented with pressure and ultrasonic dimension transducers for assessment of left ventricular (LV) performance, were given both NP and ATP. Regional blood flow was measured by radioactive microspheres. After 20 min of infusion, both drugs decreased systemic arterial pressure by 36% with minimal changes in cardiac index (CI), LV end-diastolic pressure, or heart rate. However, hypotension produced by ATP was associated with a greater CI (3.84 +/- 0.32 vs 2.97 +/- 0.35 L X min-1 X m-2) than was NP and also associated with a further decrease in systemic vascular resistance (14.4 +/- 1.4 vs 17.7 +/- 2.2 mm Hg X L-1 X min X m2). Left ventricular global function, measured by the slope of the linear regression line of the LV end-systolic pressure-diameter relation (Ees), did not change significantly after either drug. Blood flow to the coronary bed was significantly greater with ATP than with NP (231.6 +/- 30.6 vs 81.7 +/- 6.1 ml X min-1 X 100 g-1). Except for an increase in hepatic arterial blood flow with NP, neither ATP nor NP significantly altered blood flow to the brain, spinal cord, spleen, kidney, jejunum, muscle, and skin. Controlled hypotension by ATP was stable and rapidly reversible without rebound hypertension. The results of this study indicate that ATP is a rapidly acting, effective hypotensive agent that compares favorably with NP.     

Myocardial effects of adenosine- and sodium nitroprusside-induced hypotension: a comparative study in patients anaesthetized for abdominal aortic aneurysm surgery

The effects of adenosine and sodium-nitroprusside (SNP) on central and myocardial haemodynamics and metabolism were evaluated during fentanyl anaesthesia (100 micrograms.kg-1) in six patients with peripheral vascular disease. The investigation was performed during stable anaesthesia, before scheduled abdominal aortic graft surgery. Adenosine and SNP were infused intravenously in random order over 20 min, leaving a 30-min control period in between. The vasodilators were titrated in order to reduce mean arterial pressure by approximately 25%. Adenosine (90 +/- 20 micrograms.kg-1.min-1) reduced mean arterial pressure from 10.9 +/- 0.3 to 8.4 +/- 0.4 kPa (82 +/- 3 to 63 +/- 3 mmHg), and SNP (0.7 +/- 0.1 micrograms.kg-1.min-1) from 11.0 +/- 0.2 to 8.4 +/- 0.3 kPa (83 +/- 3 mmHg to 63 +/- 3 mmHg), during the hypotension period. Cardiac index remained unaffected during induced hypotension with both vasodilators, while heart rate increased during SNP infusion (8 +/- 3%) and remained unaffected with adenosine. Left ventricular stroke work index and myocardial oxygen consumption decreased during SNP infusion (33 +/- 3% and 17 +/- 5%, respectively), while these parameters were unchanged with adenosine. Adenosine hypotension increased coronary sinus flow 1-2 fold (128 +/- 26%), together with increased coronary sinus oxygen content (96 +/- 11%). In contrast, coronary sinus flow decreased during SNP hypotension (-15 +/- 4%) with unaffected coronary sinus oxygen content. It is concluded that adenosine, in contrast to SNP, is associated with a hyperkinetic myocardial circulation.     

Comparative cardiovascular effects of SNP,ATP and phentolamine during norepinephrine-induced hypertension in dogs

There has been no study comparing the advantage and disadvantage of various antihypertensive agents during surgery for pheochromocytomas because the study is difficult in clinical setting. In the present experiments using dogs, after increasing the arterial blood pressure with norepinephrine, we decreased it to the baseline with sodium nitroprusside (SNP), adenosine triphosphate (ATP), or phentolamine (PE) and compared the hemodynamic changes. A hyperdynamic state was found with ATP and with PE, but not with SNP. The norepinephrine-induced pulmonary hypertension could be successfully treated with SNP, but not with ATP or PE. The reason for these differences are thought to be the different vasodilative properties on peripheral arteries and veins. We conclude that agents that dilates the arteries and veins should be used to regulate the arterial pressure during surgical removal of a pheochromocytoma.(Murata K, Takahashi H, Ikeda K: Comparative cardiovascular effects of SNP, ATP and phentolamine during norepinephrine-induced hypertension in dogs. J Anesth 5: 396–403, 1991)     

Myocardial hemodynamics during induced hypotension: a comparison between sodium nitroprusside and adenosine triphosphate

Adenosine triphosphate (ATP) has been reported to be a hypotensive agent similar in effect to sodium nitroprusside (SNP). The purpose of this study was to examine and compare the effects of both SNP and ATP on general coronary hemodynamics, myocardial O2 consumption, and circulating catecholamines. Twelve dogs were anesthetized with 1.0% halothane and given either SNP or ATP by controlled infusion to reduce their systemic blood pressure by 50% for a 2-h period followed by a (blood pressure) recovery period. The ATP-induced hypotension was rapid, easily controlled, not accompanied by tachyphylaxis over the 120 min studied, and resulted in an increase in coronary sinus blood flow (CSBF), which plateaued at 260% above control. The increase in CSBF was almost immediate and remained at this elevated level for the duration of the induced hypotension. During the ATP-induced hypotension, there was no change in heart rate or circulating catecholamines. A 60% reduction in myocardial O2 uptake was observed, presumably from the cardiac unloading. In contrast, SNP-induced hypotension required a marked increase in dose over time, did not significantly increase CSBF, did increase heart rate, and resulted in large increases in circulating plasma catecholamines. Neither agent affected cardiac output. ATP-induced hypotension resulted in no change in cardiac lactic acid uptake, while SNP caused lactic acid production, indicating possible cardiac ischemia or cyanide toxicity.     

硝普钠降压对胃粘膜pH的影响

目的 观察硝普钠控制性降压对胃粘膜pH(i-pH)的影响。方法 选择ASAⅠ～Ⅲ级择期行神经外科手术的病人16例,术中用硝普钠控制性降低平均动脉压(MAP)至50 mmHg 90min,采用胃管法,分别于降压前、降压30、90 min和复压后120 min抽取胃液检测胃粘膜PCO_2(i-PCO_2)。同时抽动脉血监测pH、PaCO_2、PaO_2、HCO_3和BE。用Henderson-Hasselbalch公式计算i-pH。结果 i-pH于降压90 min比降压前显著降低(P<0.05),复压后120 min又恢复至降压前水平。结论 硝普钠控制性降压可降低i-pH,引起胃粘膜短暂的低灌注损害。     

外源性三磷酸腺苷在大鼠肝脏低温保存中的作用

目的研究外源性三磷酸腺苷(ATP)在大鼠肝脏低温保存中的作用及其机制.方法采用持续低温机器灌流保存模型,利用高效液相色谱、光镜及放射自显影等技术测定低温保存大鼠肝脏的能量代谢、功能、形态学变化及外源性ATP是否能进入肝细胞内.结果灌流液中不含ATP及MgCl2组(A组)和灌流液中含5 mmol/LATP、不含MgCl2组(B组),随保存时间的延长,大鼠肝细胞内ATP及Atkinson's能量转换(EC)迅速下降,两组差异不显著(P>0.05),而灌流液中含5 mmol/LATP及5 mmol/LMgCl2组(C组),ATP及EC则下降缓慢(P<0.01);A、B组乳酸脱氢酶(LDH)及天冬氨酸转氨酶(AST)迅速增高(P>0.05),C组上升较A、B组缓慢(P<0.05);保存24     

急性等容血液稀释及联合降压对犬胃肠灌注的影响

目的 观察急性等容血液稀释联合硝普钠控制性降压对犬胃肠灌注的影响。方法 健康杂种犬16只,随机分为血液稀释组和联合组。以6％羟乙基淀粉等量置换全血实施急性等容血液稀释(ANH),分别使Het降至20％～25％(HD1)、10％～15％(HD2);控制性降压期间,0．02％硝普钠溶液泵人,使MAP降至50mmHg维持30min。监测各稀释水平以及稀释联合降压时的血液动力学和胃粘膜二氧化碳分压(PgCO2)的变化。结果 (1)血液稀释组HD1及HD2时CO、SI显著增高,SVRI、PVRI显著降低(P＜0．01),MAP、HR、CVP、PAP、PCWP不变;(2)血液稀释组HDl及HD2时Hb、CaO2、CvO2、DO2显著降低(P＜0．01),而ERO2增高,VO2不变;(3)与基础值比,联合组CO、SI、MAP、SVRI、PVRI显著降低(P＜0．01);(4)血液稀释组PgCO2、胃粘膜与呼气末二氧化碳分压差(KETCO2)无显著变化;联合组PgCO2、Pg-ET CO2分别由48．6mmHg、9．8mmHg增高至70．7mmHg、29．3mmHg。结论 血液稀释联合硝普钠降压时,因静脉回心血量下降,心输出量因而降低,内脏灌注受损。     

A randomized comparison of labetalol and nitroprusside for induced hypotension

In a randomized study, labetalol-induced hypotension and nitroprusside-induced hypotension were compared in 20 patients (10 in each group) scheduled for major orthopedic procedures. Each patient was subjected to an identical anesthetic protocol and similar drug-induced reductions in mean arterial blood pressure (BP) (50 to 55 mmHg). Nitroprusside infusion was associated with a significant (p < 0.05) increase in heart rate and cardiac output; rebound hypertension was observed in three patients after discontinuation of nitroprusside. Labetalol administration was not associated with any of these findings. Arterial PO₂ decreased in both groups. It was concluded that labetalol offers advantages over nitroprusside.     

Hemodynamic and sympathetic effects of fenoldopam and sodium nitroprusside

BACKGROUND: Fenoldopam is a novel dopamine-1 receptor selective agonist that can be used as a vasodilator perioperatively to treat hypertension and to produce induced hypotension. We were interested to find out whether there were any differences between fenoldopam (FM) and sodium nitroprusside (SNP), one of the most popular vasodilators, in their effects on hemodynamics and sympathetic outflow using not only neuraxis intact but also baro-denervated animal models. METHODS: A total of 60 New Zealand white rabbits were divided into two groups of 30 each: the neuraxis-intact group and the totally baro-denervated group. Each group was further divided into three groups of 10 each to receive SNP 10 microg x kg(-1), FM 10 microg x kg(-1) or FM 20 microg x kg(-1), respectively. Mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were recorded before and after intravenous (i.v.) administration of each agent. In addition, cardiac and sympathetic baroreflex sensitivity were assessed in the neuraxis-intact animals. RESULTS: In the neuraxis-intact groups, although RSNA was increased to a similar extent in all three groups (P<0.01), the reduction of MAP with FM groups was significantly greater than with SNP (P<0.05). HR was increased only in the SNP group. Cardiac (HR) and sympathetic barosensitivity were significantly attenuated with FM 20 microg x kg(-1) as compared to the SNP group. In the baro-denervated groups, there were significant and similar degrees of reduction of MAP in all three group up to 1 min (P<0.01). MAP remained significantly decreased in the FM groups for 10 min (only 2 min with SNP) in both animal models. CONCLUSIONS: Unlike sodium nitroprusside, fenoldopam attenuates both cardiac (heart rate) and sympathetic baroreflex sensitivity, which may explain the lack of rebound hypertension with fenoldopam. The offset of hypotensive effects of fenoldopam is a significantly slower process as compared to nitroprusside, and this may be an unfavorable feature of fenoldopam should overshoot of hypotension occur.     

可乐定对硝普钠控制性降压期间血浆激素水平的影响

以择期颅脑手术患者，术前口服可乐定 ５μｇ／ｋｇ对硝普钠控制性降压期间血浆儿茶酚胺、肾素血管紧张素和抗利尿激素水平的影响。结果发现，可乐定明显降低硝普钠控制性降压期间儿茶酚胺和抗利尿激素的水平，增加肾素血管紧张素系统的活性。提示可乐定通过降低血浆儿茶酚胺和抗利尿激素水平而加强硝普钠的降压作用。