Effect of lower leg compression during cesarean section on post-spinal hypotension and neonatal hemodynamic parameters: nonrandomized controlled clinical trial

ObjectivesThis study aimed to determine the effect of lower leg compression during cesarean section (CS) on post-spinal hypotension (PSH) and neonatal hemodynamic parameters.MethodsThis study is a nonrandomized controlled clinical trial conducted in the cesarean delivery unit of the National Medical institute, Damanhour, Egypt. The sample included 120 parturients (60 intervention and 60 control). The researchers developed three tools for data collection: sociodemographic data and reproductive history interview schedule, electronic monitoring of maternal hemodynamic parameters, and neonatal hemodynamic assessment sheet. All parturients received ordinary pre-operative care. For the intervention group, a long elastic stocking (ordinary pressure 20–30 mmHg, 1 mmHg = 0.133 kPa) was applied on both legs during cesarean section. The control group received the same care without the elastic stocking.ResultsSystolic blood pressure, diastolic blood pressure, and mean arterial blood pressure were significantly higher in the intervention group throughout the entire operation period except in the last 5–15 min. Heart rate was significantly lower in the intervention group. Only 13.3% of the intervention group took ephedrine compared with 45% of the control group. Apgar score was higher among neonates of intervention group compared with the control group at 1 min. Neonatal acidosis was significantly higher in the control group than in the contral group.ConclusionLower leg compression technique can effectively reduce PSH and neonatal acidosis.     

血清白蛋白水平对血液透析低血压发生的影响

目的了解血浆白蛋白水平对血液透析时低血压发生率的影响。方法按血清白蛋白水平分为三组:血清白蛋白>35g/L组、25-35g/L组和<25g/L组,观察三组在血透期间低血压的发生率。结果随着血清白蛋白水平的下降,低血压的发生率呈升高趋势,三组的发生率分别为4.8%,6.4%,25.7%,三组间有显著性差异(P<0.01)。结论血浆白蛋白在维持血透期间的血压起着重要的作用,低白蛋白血症,尤其白蛋白<25g/L时,易发生低血压,在拟定超滤方案时应充分考虑这一因素。     

DPOAE对系统性低血压患者的耳蜗功能监测及其临床意义

目的用畸变产物耳声发射(distortion-product otoacoustic emission,DPOAE)来观察系统性低血压和慢性进行性听力损伤的关系。方法实验组为34例体检中发现的系统性低血压患者(诊断标准:舒张压<60mmHg,收缩压<90mmHg),对照组由年龄、性别相匹配的30例正常人组成,两组在同一实验室中进行了生化、心血管、耳鼻咽喉专科和纯音测听、声阻抗、DPOAE等听力学检查。将两组的各项结果进行比较。结果实验组DPOAE听力图结果显示16例患者有一个以上频率轻到中度的听力损伤,主要在低频范围。与对照组相比,实验组的DPOAE幅值在一个以上的频率低下甚至缺失。结论系统性低血压有可能是导致耳蜗功能损伤的因子之一,而DPOAE可作为早期监测此类患者耳蜗功能损伤情况的有效工具。     

异丙酚复合麻醉下髋关节置换术患者瑞芬太尼控制性降压的效果

目的探讨异丙酚复合麻醉下髋关节置换术患者瑞芬太尼控制性降压的效果。方法择期行髋关节置换术患者30例,ASA分级Ⅱ级或Ⅲ级,随机分为2组(n=15):瑞芬太尼组(R组)和硝普钠组(N组)。2组麻醉诱导气管插管后在30min内静脉输注6%羟乙基淀粉200/0.5 15ml/kg行急性高容量血液稀释,桡动脉穿刺置管监测平均动脉压(MAP)和心率(HR),颈内静脉穿刺置管监测中心静脉压,术中维持脑电双频谱指数45～55。2组于切皮前开始降压,R组和N组分别持续静脉输注瑞芬太尼0.3～0.7μg·kg~(-1)·min~(-1)、硝普钠0.5～6.0μg·kg~(-1)·min~(-1),使MAP降低到术前基础值的70%左右(60～70mm Hg)并维持至术毕。分别于急性高容量血液稀释后控制性降压前即刻(T_0)、控制性降压20min(T_1)、40min(T_2)、术毕(T_3)时抽取静脉血,测定血红蛋白(Hb)、红细胞压积(Hct)、乳酸(Lac)浓度,同时抽取动脉血,行动脉血气分析,记录开始降压至目标血压所需的时间(降压诱导时间)、停降压药后MAP恢复至基础值的时间(MAP恢复时间)及术中出血量、输血量。结果与N组比较,R组降压诱导时间、MAP恢复时间、血气分析指标及Lae水平差异无统计学意义(P>0.05),T_(1,2)时HR降低,出血量减少(P<0.05或0.01);N组有5例患者发生反射性心动过速,需使用艾司洛尔,T_3时有2例患者发生反跳性高血压,2组术后均未见并发症。结论异丙酚复合麻醉下髋关节置换术患者持续静脉输注瑞芬太尼0.3～0.7μg·kg~(-1)·min~(-1)控制性降压可控性好,降压及恢复平稳,且血液保护作用优于硝普钠。     

Blood volume and right heart haemodynamics in abrupt hypotension following sublingual isosorbide dinitrate in acute myocardial infarction

Arterial blood pressure and heart rate were measured in 43 patientswith acute myocardial infarction and a systolic blood pressure120 mmHg during sublingual administration of 5 mg of isosorbidedinitrate. In 25 of them right heart haemodynamics were alsomeasured. Severe (25%) hypotension developed in 12 patients(Group 1, systolic blood pressure 158 ± 28 to 78 ±17 mmHg, mean ± SD) but not in the remaining 31 (Group2) and was accompanied by a fall in heart rate (82 ±20 to 70 ± 22beats min^-1, P<0.05), in cardiac output(4.3 ± 0.3 to 3.2 ± 0.4l mm^-1, P<0.02, n =5) and in systemic vascular resistances (2326 ± 463 to1532 ± 442 dynes sec^-1 cm^-5, P<0.02) not present inGroup 2. The reduction in right (Group 1,8 ± 3 to 3 ±1, vs. Group 2,10 ± 3 to 6± 3 mmHg, V <0.005)and in left ventricular filling pressures (Group 1,15 ±4 to 8 ± 2, vs. Group 2,18 ± 6 to 13 ±5 mmHg, P<0.001) was more remarkable in Group 1. In thisgroup there was also a high incidence of anterior infarction(9/12, 75%). Blood volume measured in 30 patients was lowerin Group 1 but differences were not significant. A second doseof 5 mg of isosorbide dinitrate 36–48 h later producedneither symptomatic hypotension (Group 1, 147 ± 29 to129 ± 24 mmHg) nor a fall in cardiac output in any patient,whereas changes infilling pressures were comparable to thoseof the first dose. Thus, severe isosorbide dinitrate-induced hypotension in myocardialinfarction is limited to the acute phase and seems more prevalentin anterior infarction but can not be clearly predicted fromresting haemodynamic or blood volume measurements, at leastin non-hypotensive patients. Moreover, it appears to be causedby an excessive ventricular emptying due to a striking venousand arterial vasodilation, probably during a stage of a particularlydepressed ventricular compliance.     

Cardiovascular actions of cannabinoids and their generation during shock

Marijuana is a widely abused recreational drug well known for its psychoactive properties. Cannabinoids, the active ingredients of marijuana, elicit their neurobehavioral effects by interacting with the CB₁ cannabinoid receptor subtype, expressed primarily in the brain but also present in some peripheral tissues. A second receptor subtype, the CB₂ receptor, is expressed on cells of the immune system and is thought to be responsible for the immunosuppressant effects of cannabinoids. Recently, endogenous lipidlike substances have been identified, including arachidonyl ethanolamide (anandamide) and 2-arachidonyl glyceride, that bind to cannabinoid receptors and mimic many of the neurobehavioral effects of plant-derived cannabinoids. Both plant-derived cannabinoids and the endogenous ligands have been shown to elicit hypotension and bradycardia via activation of peripherally located CB₁ receptors. Possible underlying mechanisms include presynaptic CB₁ receptor mediated inhibition of norepinephrine release from peripheral sympathetic nerve terminals, and/or direct vasodilation via activation of vascular cannabinoid receptors. The latter may also be the target of endocannabinoids of vascular endothelial origin. Recent studies indicate that a peripheral endogenous cannabinoid system in circulating macrophages and platelets is activated in hemorrhagic and septic shock and may contribute to the hypotension associated with these conditions via activation of vascular cannabinoid receptors. The potential role of this mechanism in human shock conditions is under investigation. Received: 20 May 1998 / Accepted: 24 August 1998     

Hypotension and thirst in rats after isoproterenol treatment

Drinking induced in rats by systemic isoproterenol treatment is markedly attenuated after bilateral nephrectomy. The present experiments demonstrate that the hypotension produced by iso-proterenol treatment was more profound, and lasted much longer, in nephrectomized rats than in intact animals. When arterial blood pressure was partially elevated by central administration of angiotensin II or carbachol (Experiment 1) or by intraarterial infusion of epinephrine (Experiment 2), drinking behavior was restored in the nephrectomized animals and their water intakes approximated the amounts consumed by intact rats given isoproterenol. In general, an inverted U-shaped curve was found to define the relation between blood pressure and water intake in rats after isoproterenol treatment. Drinking was most probable when mean arterial blood pressures were in the range of 70–85 mm Hg, whereas rats were unlikely to drink when blood pressures were much below or above this range. These findings indicate that isoproterenol-induced thirst is not dependent on a renal dipsogen, and suggest instead that the hypersecretion of renin that occurs in intact rats is simply permissive of drinking behavior by modulating the hypotensive effects of the drug treatment.     

Intrarenal oxygen tension measured by a modified Clark electrode at normal and low blood pressure and after injection of x-ray contrast media

 The oxygen tension (pO₂) in the rat kidney was studied using a Clark microelectrode with a guard cathode behind the sensing cathode. The mean (± SEM) outer tip diameter of the electrodes used was 5.5 ± 1.9 μm. The zero-pO₂ current amounted to 12.5 ± 0.9 pA at 37°C; at air saturation it was 252 ± 22.9 pA. Rats with a systolic blood pressure (BP) above 80 mmHg (where 1 mmHg = 133 Pa) showed an average pO₂ in the cortex of 45 ± 2 mmHg and in the outer medulla of 31 ±1 mmHg. In rats with a BP below 80 mmHg a paradoxically high outer medullary pO₂ of 40 ± 4 mmHg was found, while the pO₂ in the cortex was 27 ± 4 mmHg. Changes in pO₂ were also noted in the renal cortex and outer medulla after intravenous injections of the x-ray contrast medium diatrizoate (370 mg iodine/ml). In rats with normal BP, injection of diatrizoate caused a slight fall in pO₂ in the renal cortex, from 42 ± 4 to 38 ±4 mmHg. In the medulla pO₂ decreased significantly from 34 ± 6 to 20 ±4 mmHg. Ringer’s solution did not induce any changes. Received: 9 September 1996 / Received after revision: 22 May 1997 / Accepted: 23 May 1997     

Interaction between the septal area and the subfornical organ in the control of water intake induced by thirst-eliciting procedures

Rats bearing lesions in the septal area followed by lesions in the subfornical organ were submitted to various thirst-eliciting procedures. The rats with hyperdipsia induced by lesions of the septal area drank more water than either during the control period or after lesion of the subfornical organ under the same thirst-eliciting or angiotensin-liberating stimuli (polyethyleneglycol, isoproterenol, water deprivation and ligation of the inferior vena cava). The overdrinking elicited by lesions in the septal area was blocked after lesion of the subfornical organ. Neither hypovolemia, nor hypotension or water deprivation could elicit increased water intake in animals whose subfornical organ had been destroyed. Animals with lesions in the subfornical organ showed decreased water intake after cellular dehydration. The results obtained suggest that the subfornical organ acts as a more important structure than the septal area in the regulation of water intake elicited by angiotensin, with two opposite effects: a direct one facilitating water intake, and an indirect one inhibiting the septal area. The septal area has an inhibitory effect on the subfornical organ and on water intake.     

Systemic Hemodynamic Changes in Low-Dose Ethanol Embolotherapy for Soft-Tissue Arteriovenous Malformations

Background Ethanol embolotherapy is considered an optimal choice for the treatment of arteriovenous malformations(AVMs);however,there are some complications associated with this treatment.This study aimed to prospectively investigate systemic hemodynamic changes in high-flow AVMs using ethanol embolotherapy.Methods From September 2012 to September 2014,34 male patients and 26 female patients with AVMs who underwent embolotherapy(100 sessions in total)with absolute ethanol were included in this study.Invasive systolic blood pressure(SBP)and heart rate(HR)were recorded before and after each injection and throughout the procedure.Differences between the initial and highest SBP(ΔmaxSP)and HR values(ΔmaxHR),as well as the initial and final SBP(ΔSP)and HR(ΔHR)values,were analyzed.We aimed to explore the potential association between these values and the amount of ethanol that was used.Results The total ethanol used was variable(0.01–0.40 mL/kg;mean,0.20 mL/kg).SBP and HR increased after ethanol injection in most sessions(91 in 100 sessions).SBP decreased in 9 sessions(9 in 100 sessions),while HR,oxygen saturation,and end-tidal CO2 decreased in one of the 9 sessions.ΔmaxSP andΔmaxHR averaged 38.4 mmHg and 27.8 bpm,respectively(both P<0.05),whileΔSP andΔHR averaged 3.4 mmHg and 4.0 bpm,respectively(both P<0.05).ΔmaxSP andΔmaxHR were positively correlated with the total dose of ethanol injected.Conclusions Elevations in SBP and HR during ethanol embolotherapy are common,temporary,and most likely pain-mediated;these increases tend to be positively correlated with ethanol dose.Hypotension may be regarded as an acute complication of ethanol embolotherapy.Hypotension combined with bradycardia,oxygen desaturation,and decreased end-tidal CO2 may be a potential predictor of cardiovascular collapse.