Haemodynamic changes during epidural caesarean delivery

The cardiovascular changes during epidural caesarean delivery were studied, using a non-invasive cardiac output monitor (BoMed NCCOM3-R7). Two different regimens were used to control hypotension (A = 15 ml/kg of 3% dextran 70, B = 7.5 ml/kg of 3% dextran 70 followed by an infusion of 17.5 mg of ephedrine). Cardiac index (CI) and heart rate (HR) increased after delivery and oxytocin administration (P < 0.001) and maximum values were recorded 1-1.5 min after administration of oxytocin. The maximum increase in CI was 76% (A) and 117% (B), in HR 42% (A) and 56% (B), and in SI 23% (A) and 47% (B) compared with values before anaesthesia. The increase in cardiac output after delivery was greater than that measured previously, which might be because impedance cardiac output is a continuous method. It is also suggested that the most pronounced changes are augmented by the use of a bolus injection of 10 units oxytocin i.v.     

全身麻醉和硬膜外麻醉期间胃粘膜pH的变化及意义

目的 研究全身麻醉和硬膜外麻醉期间胃粘膜ｐＨ（ｐＨｉ）的变化及ｐＨ与术后应激性溃疡的关系。方法 ３０例择期下腹部手术患者,随机分为两组,全麻组,芬太尼＋依托咪酯＋琥珀胆碱诱导,维库溴铵＋安氟醚维持,硬膜外组２％利多卡因。麻醉前１小时将Ｔｒｉｐ导管置入内,麻醉诱导前（Ｔ１）诱导后６０分钟（Ｔ２）,１２０分钟（Ｔ３）分别测定ｐＨｉ,Ｐｈａ,ＰａＣＯ２,ＭＡＰ和ＨＲ,术后随访３天观察胃经流管的出血情况。     

硬膜外麻醉时皮肤电传导变化的临床观察

目的探讨硬膜外麻醉时皮肤电传导(SC)基态值和反应波的变化。方法选择25例ASAⅠ或Ⅱ级下肢手术患者。记录硬膜外给药前(T0)、给予1%利多卡因5ml后5min(T1)、给予0.75%罗哌卡因10ml后5、10、15、25和45min(T2～T6)时的SC基态值(SC0)、针刺非阻滞区SC反应波的振幅差值(SC1)和痛觉阻滞区的SC反应波的振幅差值(SC2)。使用ROC曲线、逻辑回归分析评价SC反应波的振幅差值区分痛觉阻滞区和非阻滞区的准确性。结果与T0时比较,T3～T6时的SC0及SC1的均值明显降低(P<0.05),T1～T6时SC2明显低于SC1(P<0.05)。SC反应波的振幅差值ROC曲线下面积为0.928±0.017(P<0.01),特异性与敏感性分别为78%和88%,预测整体准确率84%。结论 SC基态值及反应波振幅差值的变化对定位硬膜外麻醉平面有一定指导作用。     

Central temperature changes are poorly perceived during epidural anesthesia.

Hypothermia and shivering are common during epidural anesthesia for cesarean delivery but are not always accompanied by a sensation of coldness. To test the hypothesis that central temperature changes are not perceived during epidural anesthesia, we measured central and skin temperatures and thermal perception in 30 patients undergoing cesarean delivery with epidural anesthesia. Central temperature decreased 1.0 +/- 0.6 degrees C from control values during anesthesia and surgery, but thermal perception scores did not reflect central temperatures (P = 0.56) or changes in central temperature (P = 0.63). A feeling of warmth was significantly correlated with increased mean skin temperature (P = 0.02) and increased upper body skin temperature (P = 0.03). We conclude that central temperature is poorly perceived and is less important than skin temperature in determining thermal perception during high levels of epidural anesthesia.     

麻黄碱纠正硬膜外阻滞低血压前后的血流动力学改变

对１７只犬用有创监测研究硬膜外阻滞后低血压和麻黄碱纠正其低血压的血流动力学改变。结果表明：硬膜外阻滞后肝血管阻力、肾血管阻力均降低．每搏肝动脉血流量、每搏门静脉血流量、每博肾动脉血流量有不同程度增加。麻黄碱纠正硬膜外阻滞低血压时，肝、肾血流量均能保持在较好的正常水个。     

Observational study of changes in epidural pressure and elastance during epidural blood patch in obstetric patients

BackgroundDuring an epidural blood patch, we inject blood until the patient describes mild back pressure, often leading to injection of more than 20 mL of blood. We undertook this study to measure the epidural pressures generated during an epidural blood patch and to identify the impact of volume on epidural elastance in obstetric patients.MethodsThis study was performed in postpartum patients who presented for an epidural blood patch with symptoms consistent with a postdural puncture headache. After identification of the epidural space using loss of resistance to air or saline, we measured static epidural pressure after each 5-mL injection of blood. Models were then fitted to the data and the epidural elastance and compliance calculated.ResultsEighteen blood patches were performed on 17 patients. The mean final volume injected was 18.9 ± 7.8 mL [range 6–38 mL]. The mean final pressure generated was 13.1 ± 13.4 mmHg [range 2–56 mmHg]. A curvilinear relationship existed between volume injected and pressure, which was described by two models: (1) pressure = 0.0254 × (mL injected)² + 0.0297  mL, or (2) pressure = 0.0679 × mL^1.742. The value for r² was approximately 0.57 for both models. We found no correlation between the final pressure generated and the success of the epidural blood patch.ConclusionsWe found a curvilinear relationship between the volume of blood injected during an epidural blood patch and the pressure generated in the epidural space. However, there was a large variation in both the volume of blood and the epidural pressure generated. The clinical importance of this finding is not known. A larger study would be required to demonstrate whether pressure is a predictor of success.     

Hemodynamic changes in normovolemic and hypovolemic canines during epidural block]

Hemodynamic changes were studied in normovolemic and hypovolemic canines during epidural block. In normovolemic canines after epidural block, stroke volume (SV) increased, heart rate (HR) slowed down and total peripheral resistance (TPR) and mean arterial pressure (MAP) decreased. In addition, hepatic vascular resistance (HVR) and renal vascular resistance (RVR) decreased but quantity of hepatic artery per beat (QHR/HR), quantity of hepatic artery per beat (QPV/HR) and quantity of renal artery per beat (QRA/HR) increased significantly. In hypovolemic canines, the hemodynamic changes after epidural block were similar in normovolemic ones but more abrupt. The increase of QHA/HR, QPV/HR and QRA/HR was not statistically significant, but minute hepatic blood volume quantity of hepatic artery (QHA), quantity of portal vein (QPV) and hepatic blood flow (HBF) decreased significantly. In hypovolemic canines during epidural block, ischemic injury of the liver should be alerted and abrupt hemodynamic changes should be well controlled.     

Local metabolic changes in subcutaneous adipose tissue during intravenous and epidural analgesia

BACKGROUND: This clinical study aimed at investigating the impact of postoperative thoracic epidural analgesia on extracellular glycerol concentration and glucose metabolism in subcutaneous adipose tissue, using the microdialysis technique. The sympathetic nervous activity, which can be attenuated by epidural anesthesia, influences lipolysis and the release of glycerol. METHODS: Fourteen patients who underwent major abdominal or thoraco-abdominal surgery were studied postoperatively over 3 days. For postoperative analgesia the patients were prospectively randomized to receive either thoracic epidural analgesia with a bupivacaine/morphine infusion (EPI-group, n=6) or a continuous i.v. infusion of morphine (MO-group, n=8). The concentration of glycerol, glucose and lactate in the abdominal and deltoid subcutaneous adipose tissue were measured using a microdialysis technique. RESULTS: The abdominal glycerol levels were equal in both groups. In the deltoid region of the EPI-group, glycerol concentrations started to increase on Day 2, and reached significantly higher levels on Day 3 compared with the MO-group. The glucose and lactate levels showed no differences between groups in the two regions. CONCLUSION: The uniform glycerol levels in abdominal subcutaneous adipose tissue in conjunction with the difference in glycerol levels in the deltoid area indicate that the local lipolysis is different in the two study groups. This might be explained by a regional metabolic influence of thoracic epidural analgesia, possibly via the sympathetic nervous system.     

全麻联合硬膜外阻滞下经典式原位肝移植术期间血流动力学的改变

目的 观察全麻联合硬膜外阻滞行经典式原位肝移植期间血流动力学的变化.方法 24例肝癌全麻联合硬膜外阻滞下行经典式原住肝移植术,麻醉前放置Swam-Gaze导管,右桡动脉导管及右股静脉导管,监测麻醉前期,切皮时,无肝前期末,无肝期5 min,无肝期30 min,新肝期15 min及术毕各个时期血流动力学参数,用t检验组间变化的差异性.再分别以麻醉前作时照处理数据.结果 24例肝癌患者均行经典式原位肝移植术,手术时间(435±48)min,术中出血量(2 258±325)ml.术中输库存浓缩RBC(6.6±1.5)U、血浆(785±68)ml、平衡液(1 856±86)ml、血浆代用品(1 625±115)ml.①切皮时,中心静脉压(CVP),股静脉压(FVP),平均肺动脉压(MPAP),肺毛细血管楔压(PCWP)下降(P≤0.05或P≤0.01),心输出量(CO),心指数(CI)也随着降低(P≤0.05),MPAP降低(P≤0.05).②无肝前期末,CVP,FVP,MPAP,PCWP进一步下降(P≤0.01),CO和CI也随着进一步下降(P≤0.01),MPAP也进一步降低(P≤0.01).③无肝期5 min,CVP,MPAP,PCWP,CO,CI以及MPAP进一步剧烈下降(P≤0.01),即使周围血管阻力和肺血管阻力升高(P≤0.05),MPAP依然进一步剧烈下降(P≤0.01),但FVP骤然升高(P≤0.01).④无肝期30 min,股静脉压有所回落(P≤0.01),MPAP,PCWP,CO以及CI较无肝期5 min有回升趋势(P≤0.01).⑤新肝期,CVP,MPAP,PCWP,CO,CI以及MPAP明显回升(P≤0.01);周围阻力下降(P≤0.05),FVP骤然下降(P≤0.01).⑥手术结束时,CVP,FVP及MPAP较新肝期进一步回升(P≤0.01),其他指标如MAP,MPAP,PC聊,CO以及CI也基本上恢复至麻醉前水平(P≤0.05).FVP基本上和CVP相差不大(P≤0.05).结论 全麻联合硬膜外阻滞下原位肝移植术期间,协同麻醉作用,减少全身麻醉药对患者重要脏器的影响,扩张硬膜外阻滞区域血管,在门静脉和下腔静脉阻断时,可增加回心循环的血流量,部分代替体外静脉-静脉技术的作用,减少血流动力剧烈波动.     

Hemodynamic and respiratory changes in athletes during deep breath-hold diving

BACKGROUND: The study analysed the hemodynamic and respiratory aspects of deep breath-hold diving. METHODS: One male (59-year-old) and one female (32-year-old) subject were enrolled. They were both champion deep breath-hold divers. The dives were performed in the wet compartment of the hyperbaric chamber, first in thermoneutral (35 degrees C) and then cool (25 degrees C) water. The subjects were monitored using ECG recordings; percentage cannulation of the right radial artery using an aseptic technique. Stroke volume (SV) and cardiac output (CO) were measured using impedance cardiography (Bomed). RESULTS: Variations were observed in heart rhythm, cardiac output, arterial blood pressure and breathing. Both bradycardia and many hemodynamically effective dysrhythmias influenced CO, which showed a tendency to decrease in the diver in cool water. Changes in CO were caused by concomitant changes in HR as SV showed no significant variations. During breath-hold diving, a drop in intra-thoracic pressure is likely to enhance redistribution of blood from the periphery to the chest, which might distend the heart even more, contributing to dysrhythmogenesis. The observation that dysrhythmias were more frequent in cool water is in line with these concepts. CONCLUSIONS: Only two leading divers were recruited in this study and observed for hemodynamic and respiratory changes. However, these findings are in line with similar studies carried out by other authors.     

Cardiovascular changes during deep halothane anaesthesia in infants and children

Cardiac output, blood pressure and heart rate were measured with noninvasive techniques before, during and after induction of anaesthesia with halothane and after intubation in unpremedicated infants and in diazepam-atropine premedicated children presenting for elective surgery. Cardiac output was measured with pulsed doppler echocardiography. Left ventricular shortening fraction was estimated with M-mode echocardiography during induction. Induction with halothane in infants caused significant decrements in blood pressure, cardiac index, stroke volume index and significant depression of left ventricular shortening fraction. Induction with halothane in diazepam-atropine premedicated children caused a significant increase in heart rate but significant decreases in blood pressure, stroke volume index and left ventricular shortening fraction while cardiac index decreased slightly. Intubation in infants caused a mild increase in heart rate compared with pre-induction values but blood pressure, cardiac index and stroke volume index remained below pre-induction values. Intubation in diazepam-atropine premedicated children caused significant increases in heart rate and cardiac index, and a non-significant increase in blood pressure but stroke volume index remained significantly below pre-induction values. Healthy infants and children tolerate induction of anaesthesia with halothane to a depth to permit intubation but large reductions in cardiac output and myocardial contractility are expected with subsequent reductions in blood pressure.