Caesarean section to prevent supine hypotension syndrome

BACKGROUND: The objective of this study was to investigate the effects of posture after spinal anesthesia with 2% lidocaine and 0.5% isobaric bupivacaine in parturients undergoing caesarean section and to demonstrate our modified combined spinal epidural (CSE) method. METHODS: The patients in groups 2%lido (S) and (L) received 2 ml of 2% lidocaine and the patients in groups 0.5%bupi (S) and (L) received 1.6 ml of 0.5% isobaric bupivacaine. The two (S) groups were turned into the supine position after spinal injection and the two (L) groups were kept on their left side for 10 or 15 minutes before they turned supine. All the patients received an epidural injection of 6 ml of 2% lidocaine or 6 ml of 1% ropivacaine 16 minutes after spinal injection. RESULTS: There was a significant difference in the level of analgesia between the (S) groups and the (L) groups 10 minutes after spinal injection (P<0.05). The systolic blood pressures 10 minutes after spinal injection were significantly decreased than those before spinal injection in the (S)groups (P<0.05). CONCLUSIONS: Our modified CSE method can provide beneficial effects on full term pregnant women by preventing hypotension due to spinal anesthesia.     

Volume preload: lack of effect in the prevention of spinal-induced hypotension at caesarean section

A randomized double-blind study of 40 women was performed to compare blood pressure changes between two groups of women following induction of spinal anaesthesia for elective caesarean section. One group received a 1 L Ringer's solution preload, administered over 10 min, before spinal anaesthesia while the other group received no preload. In both groups a prophylactic infusion of ephedrine (60 mg in Ringer's solution 1000 ml) was started immediately following intrathecal injection of local anaesthetic. There was no significant difference either in the ephedrine requirements or the incidence of hypotension between the two groups. There were no differences between the groups in terms of neonatal outcome as assessed by Apgar score, umbilical arterial and venous blood pH, and Neonatal Adaptive Capacity Scores. When ephedrine is infused prophylactically immediately following spinal anaesthesia for elective caesarean section, a 1000 ml crystalloid preload confers no advantages in terms of maternal blood pressure control or neonatal outcome.     

ED95 of phenylephrine to prevent spinal-induced hypotension and/or nausea at elective cesarean delivery

BackgroundThe purpose of this trial was to determine the 95% effective dose (ED95) of phenylephrine by intermittent i.v. bolus, to prevent spinal-induced hypotension and/or nausea at elective cesarean delivery.MethodsThe study was conducted in a double-blinded fashion in 50 patients undergoing elective cesarean delivery under spinal anesthesia. The dose of phenylephrine was determined using up-down sequential allocation, modified by a variation of the Narayana rule. Systolic pressure and heart rate were assessed every minute until uterine incision. The first patient was assigned a 40-μg dose, and the dose to subsequent patients varied by 10-μg increments or decrements. An adequate response was defined as absence of hypotension (systolic pressure <80% of baseline) and nausea. The study solution was given immediately after spinal administration, without prior pressure measurement, and thereafter when the systolic pressure was ? control values. fell below baseline. The ED95 was determined by a logistic model with non-log-transformed doses, using Firth’s penalized maximum likelihood method with 95% confidence intervals based on penalized profile likelihood.ResultsThe ED95 of phenylephrine was estimated as 159 μg (95% confidence interval: 122–371 μg), although the largest dose given in the study was only 120 μg. Hypertension (systolic blood pressure >120% of baseline) was observed in 14 cases, immediately after intrathecal injection and prophylactic phenylephrine administration in all cases.ConclusionThe ED95 of phenylephrine, administered as intermittent boluses to prevent pre-delivery spinal-induced hypotension and/or nausea at elective cesarean delivery, is at least 122 μg (lower limit of the confidence interval). The safety of this dose warrants further studies.     

Colloid vs. crystalloid preloading to prevent maternal hypotension during spinal anesthesia for elective cesarean section

Background:  Hypotension associated with spinal anesthesia for cesarean section is still a clinical problem. Colloid solutions seem preferable to crystalloid solutions for preloading. In most studies the overall rate of hypotension is reported. Few studies have, however, investigated the maternal and neonatal consequences of different levels of maternal hypotension.
Methods:  In this randomized, double-blinded study 110 patients presenting for elective cesarean section received either 1000 ml acetated Ringer's solution or 1000 ml 3% dextran 60 solution immediately before spinal anesthesia. The effect on overall hypotension, clinically significant hypotension (hypotension associated with maternal discomfort defined as nausea, retching/vomiting, dizziness or chest symptoms) and severe hypotension (systolic arterial pressure <80 mmHg) was studied.
Results:  Dextran reduced the incidence of overall hypotension from 85 to 66% ( P =  0.03), reduced the incidence of clinically significant hypotension from 60 to 30% ( P =  0.002) and reduced the incidence of severe hypotension from 23 to 3.6% ( P =  0.004) compared to Ringer's solution. There were neither differences in neonatal outcome between treatment groups nor between neonates grouped after severity of maternal hypotension.
Conclusion:  Clinically significant hypotension seems to be a more suitable outcome variable than overall hypotension. The protective effect of the colloid solution increased with increased severity of hypotension.     

Epidural volume extension at Caesarean section

Editor—I read with interest the article on epidural volumeextension (EVE).¹ The proposed mechanism of EVE is that it fillsthe epidural space with liquid, which results in compressionof the subarachnoid space leading to the local anaesthetic init to be pushed upwards. On the few occasions I have used EVE,I have often wondered why the injected fluid does not run backout of the     

Spinal-induced hypotension at caesarean section

Spinal anaesthesia is preferred for caesarean section, yet hypotension remains a significant problem and may adversely affect mother and baby. Understanding the physiological causes is essential to direct management. The international consensus of management includes vasopressors, intravenous fluids and avoidance of aorto-caval compression. Phenylephrine by infusion is now the vasopressor of choice. Low-dose spinal anaesthesia can reduce the incidence but risks inadequate anaesthesia. Novel means of predicting or more rapidly detecting spinal-induced hypotension include the use of continuous non-invasive blood pressure and cardiac output monitoring devices. Computer-aided closed-loop feedback systems with automated delivery of vasopressors permit timely treatment but remain outwith clinical practice.     

Spinal-induced hypotension at caesarean section

Spinal anaesthesia is preferred for caesarean section, yet hypotension remains a significant problem and may adversely affect mother and baby. Understanding the physiological causes is essential to direct management. The international consensus of management includes vasopressors, intravenous fluids and avoidance of aorto-caval compression. Phenylephrine by infusion is now the vasopressor of choice. Low-dose spinal anaesthesia can reduce the incidence but risks inadequate anaesthesia. Novel means of predicting or more rapidly detecting spinal-induced hypotension include the use of continuous non-invasive blood pressure and cardiac output monitoring devices. Computer-aided closed-loop feedback systems with automated delivery of vasopressors permit timely treatment but remain outwith clinical practice.     

Reduction in spinal-induced hypotension with ondansetron in parturients undergoing caesarean section: a double-blind randomised, placebo-controlled study

BackgroundSubarachnoid block is the preferred method of anaesthesia for caesarean section, but is associated with hypotension and bradycardia, which may be deleterious to both parturient and baby. Animal studies suggest that in the presence of decreased blood volume, 5-HT may be an important factor inducing the Bezold Jarisch reflex via 5-HT3 receptors located in intracardiac vagal nerve endings. In this study, we evaluated the effect of ondansetron, as a 5-HT3 receptor antagonist, on the haemodynamic response following subarachnoid block in parturients undergoing elective caesarean section.MethodsFifty-two parturients scheduled for elective caesarean section were randomly allocated into two groups. Before induction of spinal anaesthesia Group O (n = 26) received intravenous ondansetron 4 mg; Group S (n = 26) received normal saline. Blood pressure, heart rate and vasopressor requirements were assessed.ResultsDecreases in mean arterial pressure were significantly lower in Group O than Group S from 14 min until 35 min. Patients in Group O required significantly less vasopressor (P = 0.009) and had significantly lower incidences of nausea and vomiting (P = 0.049).ConclusionOndansetron 4 mg, given intravenously 5 min before subarachnoid block reduced hypotension and vasopressor use in parturients undergoing elective caesarean section.     

Severe hypotension is not essential for isoflurane neuroprotection against forebrain ischemia in mice

BACKGROUND: Volatile anesthetics provide protection in experimental models of global cerebral ischemia. To date, all models evaluated have included profound systemic arterial hypotension as a component of the ischemic insult. This study was designed to determine if isoflurane protection persists in a global insult devoid of hypotension. METHODS: C57BL/6J mice having a high incidence of posterior communicating artery atresia were anesthetized with isoflurane (1.2%) or fentanyl/N2O and subjected to bilateral carotid artery occlusion for 15 min or 20 min with normotension (80-110 mmHg mean arterial pressure) or for 10 min with hypotension (35 mmHg mean arterial pressure). Three days later, neurologic function and histologic damage were assessed. Other mice underwent measurement of intraischemic cerebral blood flow (4-iodo-N-methyl-[14C]antipyrine autoradiography) or plasma norepinephrine. RESULTS: Isoflurane reduced the percentage of hippocampal CA1 dead neurons (e.g., 10 min bilateral carotid occlusion + hypotension: 43 +/- 18 (isoflurane) vs. 67 +/- 20 (fentanyl/N2O), P = 0.003; 20 min bilateral carotid occlusion + normotension: 49 +/- 27 (isoflurane) vs. 71 +/- 22 (fentanyl/N2O), P = 0.003). Isoflurane also reduced CA3 damage and improved neurologic function under all conditions. Intraischemic forebrain blood flow was similar during bilateral carotid occlusion plus normotension for the two anesthetic states. Plasma norepinephrine values were greater when hypotension was added to the ischemic insult. CONCLUSIONS: Isoflurane resulted in improved neurologic function and reduced histologic damage regardless of the presence or absence of systemic hypotension during the ischemic insult. This indicates that beneficial effects of isoflurane are most likely attributable to direct effects at the neuronal level as opposed to indirect effects resulting from interactions with profound hypotension.     

Propanidid for anaesthetic induction at Caesarean section.

In 50 healthy mothers scheduled for elective Caesarean section, anaesthesia was induced with propanidid (7 mg/kg body weight). Thereafter, ventilation was controlled with nitrous oxide, oxygen and muscle relaxants. A further dose of propanidid (1 mg/kg body weight) was administered 3 minutes after the initial injection of this drug, as a means of preventing maternal awareness during equilibration with the anaesthetic gas mixture. The acid-base status of the mothers before the induction of anaesthesia, and at delivery, revealed a mild degree of respiratory alkalosis with a compensatory metabolic acidosis. Umbilical cord blood gas results indicated the presence of significant fetal acidosis, both respiratory (mean pCO2 Uv 46,3 torr (SD 11,3) and Ua 54,3 torr (SD 12,0)), and metabolic (mean base excess Uv-9 mEq/l (SD 4,2) and Ua-11,8 mEq/l, (SD 5,0)) in origin. The average umbilical cord blood oxygen tensions were Uv 25,9 torr (SD 10), and Ua 15,4 torr (SD 8,5); mean maternal to fetal base-excess gradients were Ma-Uv 4,1 mEq/l (SD 2,8) and Ma-Ua 6,5 mEq/l (SD 3,5). Five mothers (10%) offered convincing evidence of factual recall during surgery, and 3 of these were aware of pain. Nausea and vomiting occurred in 5 patients and in 4 there were clinical signs of postoperative chest infection. The degree of fetal biochemical asphyxia, and the incidence of maternal awareness during surgery, were significantly greater than previously reported when thiopentone was used for the induction of anaesthesia for Caesarean section. The results obtained are discussed, and the conclusion is drawn that propanidid for anaesthesia appears to offer no advantage over thiopentone in obstetric practice.     

Acute inversion of the uterus at Caesarean section

Two cases of acute inversion of the uterus that occurred through the uterine incision at the time of Caesarean section are described. These represent only the sixth and seventh cases reported in the literature at this time. The implications for the anaesthetist are discussed.     

Multivariate study of risk factors for arterial hypotension in pregnant patients at term undergoing Caesarean section under subarachnoid anesthesia

OBJECTIVES: The most common and potentially dangerous complication of spinal anesthesia for cesarean section is arterial hypotension. The aim of this study was to analyze maternal and gestational factors that might affect risk of arterial hypotension in full-term parturients undergoing cesarean section. MATERIAL AND METHOD: We enrolled full-term parturients scheduled for elective cesarean section under spinal anesthesia. Spinal puncture was performed at L2-L3 using an atraumatic Sprotte-type needle. We administered 12.5 mg of hyperbaric 0.5% bupivacaine and 12.5 micrograms of fentanyl. Arterial hypotension was defined as a decrease in systolic pressure of at least 20% or a decrease to a pressure below 100 mmHg. Multivariate analysis was performed to identify factors related to the presentation of hypotension appearing in the interval between spinal puncture and birth. RESULTS: The incidence of arterial hypotension was 33.3%. Statistical analysis revealed that integrity of the amniotic sac, parity and elective cesarean were significantly associated with a higher incidence of arterial hypotension (p < 0.03). CONCLUSIONS: Identifying risk for multiparous parturients with intact amniotic sacs scheduled for elective cesarean can be worthwhile if greater preventive measures are taken in such patients to reduce the incidence and intensity of arterial hypotension.     

Re-evaluation ofim ephedrine as prophylaxis against hypotension associated with spinal anaesthesia for Caesarean section

Purpose

To assess the safety and efficacy of 37.5 mg ephedrineim in preventing hypotension associated with spinal anaesthesia for Caesarean section.

Methods

In a double-blind randomised controlled study, 40 patients (20 in each group) were given either 37.5 mg ephedrine or placeboim. The following parameters were recorded: (i) blood pressure; (ii) heart rate; (iii) ephedrineiv supplementation; (iv) umbilical venous blood gases and neonatal Apgar scores.

Results

The incidence of hypertension in the study group was 30% compared with 20% for the control group (P:NS). There was no difference in mean highest blood pressure or mean highest heart rate between the groups. The incidence of hypotension was lower but not significantly lower in the study group (50%) than in the control group (80%) (P:NS). However, the incidence of delayed hypotension was only 10% in the study group patients compared with 50% in the control group patients (P < 0.05).

Conclusion

Giving 37.5 mg ephedrineim prior to spinal anaesthesia was not associated with reactive hypertension or tachycardia. Intramuscular ephedrine provided more sustained cardiovascular support than intravenous ephedrine.