Randomized double-blind comparison of ephedrine and phenylephrine for management of post-spinal hypotension in potential fetal compromise

BackgroundMost studies comparing phenylephrine and ephedrine have been conducted during elective caesarean sections in healthy mothers with no fetal compromise. The effect of vasopressors on fetal outcome may differ between healthy and compromised fetuses. There has been little research into the effect of phenylephrine and ephedrine, when used for management of post-spinal hypotension in the presence of potential fetal compromise.MethodsHealthy women with a singleton pregnancy undergoing emergency caesarean section for fetal compromise under spinal anaesthesia were studied. One-hundred-and-six consecutive subjects, who developed hypotension after spinal anaesthesia, were randomly allocated to two groups of 53 each, to receive either phenylephrine (Group P) or ephedrine (Group E). For every systolic blood pressure reading <100 mmHg patients received phenylephrine 100 μg or ephedrine 8 mg depending on group allocation. Umbilical blood gas parameters and Apgar scores were recorded.ResultsThere was no statistically significant difference in umbilical arterial pH (P=0.79), umbilical venous pH (P=0.98), other blood gas parameters, incidence of fetal acidosis (P=1.00) and Apgar scores. The number of hypotensive episodes, vasopressor doses for treatment of the first hypotensive episode and the total number of doses used during the study period were comparable. The median [IQR] total number of doses of phenylephrine and ephedrine used before delivery were 2 [1–2] and 2 [1–2], respectively (P=0.67). More patients receiving ephedrine (24.5%) developed tachycardia than those receiving phenylephrine (3.8%) (P=0.004). Bradycardia was more common with phenylephrine, with 39.6% of patients in Group P as compared to only 1.9% of patients in Group E developing a heart rate <60 beats/min after vasopressor administration (P=0.001).ConclusionsBoth phenylephrine 100 μg and ephedrine 8 mg boluses are equally efficacious when treating post-spinal hypotension in the presence of potential fetal compromise. However, phenylephrine may be a better choice in the presence of maternal tachycardia.     

A comparison of the haemodynamic effects of lateral and sitting positions during induction of spinal anaesthesia for caesarean section

BackgroundHypotension during spinal anaesthesia occurs commonly in parturients. By influencing spread of local anaesthetic, maternal position may affect the speed of onset of sensory block and thus the haemodynamic effects. The aim of this study was to determine whether inducing spinal anaesthesia for caesarean section using plain bupivacaine in the lateral position would result in less hypotension compared with the sitting position.MethodsOne hundred American Society of Anesthesiologists physical status I and II patients undergoing elective caesarean section were randomised to receive spinal anaesthesia in the lateral position (Group L) or the sitting position (Group S). Using the L3-4 interspace, patients received intrathecal plain bupivacaine, 10 mg or 12 mg according to their height, after which they were placed immediately in the supine position with left uterine displacement. Maternal blood pressure was measured every minute for 10 min, every three min for 20 min and 5-minutely thereafter. Hypotension was defined as a fall in systolic blood pressure >20% or a value <90 mmHg.ResultsThere was no difference in the lowest recorded systolic blood pressure in Group L (99.2 ± 8.9 mmHg) compared with Group S (95.4 ± 12.3 mmHg, P = 0.081). However, the lowest recorded mean arterial pressure was greater in Group L (72.9 ± 11.2 mmHg) than in Group S (68.2 ± 9.6 mmHg; P = 0.025). The incidence of hypotension was lower in Group L (17/50, 34%) than in Group S (28/50, 56%; P = 0.027). Onset of hypotension was similar between groups.ConclusionHypotension occurred less frequently when spinal anaesthesia for caesarean using plain bupivacaine was induced with patients in the lateral compared with the sitting position. Values for the lowest recorded mean arterial pressure were greater but values for the lowest recorded systolic blood pressure were similar for patients in the lateral position group.     

The effect of intravenous ondansetron on maternal haemodynamics during elective caesarean delivery under spinal anaesthesia: a double-blind,randomised, placebo-controlled trial

BackgroundSpinal anaesthesia for caesarean delivery is frequently associated with adverse effects such as maternal hypotension and bradycardia. Prophylactic administration of ondansetron has been reported to provide a protective effect. We studied the effect of different doses of ondansetron in obstetric patients.MethodsThis prospective double-blind, randomised, placebo-controlled study included 128 healthy pregnant women scheduled for elective caesarean delivery under spinal anaesthesia. Women were randomly allocated into four groups (n = 32) to receive either placebo or ondansetron 2, 4 or 8 mg intravenously before induction of spinal anaesthesia. Demographic, obstetric, intraoperative timing and anaesthetic variables were assessed at 16 time points. Anaesthetic variables assessed included blood pressure, heart rate, oxygen saturation, nausea, vomiting, electrocardiographic changes, skin flushing, discomfort or pruritus and vasopressor requirements.ResultsThere were no differences in the number of patients with hypotension in the placebo (43.8%) and ondansetron 2 mg (53.1%), 4 mg (56.3%) and 8 mg (53.1%) groups (P = 0.77), nor the percentage of time points with systolic hypotension (7.3% in the placebo group and 11.1%, 15.7% and 12.6% in the ondansetron 2, 4 and 8 mg groups, respectively, P = 0.32). There were no differences between groups in ephedrine (P = 0.11) or phenylephrine (P = 0.89) requirements and the number of patients with adverse effects.ConclusionsIn our study, prophylactic ondansetron had little effect on the incidence of hypotension in healthy parturients undergoing spinal anaesthesia with bupivacaine and fentanyl for elective caesarean delivery.     

Haemodynamic effects of glycopyrrolate pre-treatment before phenylephrine infusion during spinal anaesthesia for caesarean delivery

BackgroundPhenylephrine given during spinal anaesthesia for caesarean delivery often induces a decrease in heart rate which may decrease cardiac output. Anticholinergic drugs may be given to attenuate this effect but may also cause more labile blood pressure. This study evaluated the effects of glycopyrrolate pre-treatment on non-invasively measured cardiac output and accuracy of blood pressure control.MethodsAt induction of spinal anaesthesia for caesarean delivery, 104 patients randomly received intravenous glycopyrrolate 4 μg/kg or saline placebo. Systolic blood pressure, measured at 1-min intervals, was maintained near baseline using closed-loop feedback computer-controlled phenylephrine infusion with crystalloid cohydration. Cardiac output and stroke volume were measured using suprasternal Doppler ultrasonography at baseline and 5-min intervals for 20 min. Blood pressure control was assessed using performance error calculations.ResultsEleven patients were excluded. Patients who received glycopyrrolate (n = 45) had greater cardiac output over time (P < 0.001), greater heart rate over time (P < 0.001), similar stroke volume over time (P = 0.95), and lower median phenylephrine infusion rate (P = 0.006) compared with control (n = 48). There was no difference in the incidence of hypotension between groups. Analysis of blood pressure control showed greater positive bias, greater inaccuracy and greater wobble in the glycopyrrolate group (all P < 0.05). Neonatal outcome was similar between groups.ConclusionsGlycopyrrolate 4 μg/kg given at the start of a phenylephrine infusion increased heart rate and cardiac output but also decreased accuracy of blood pressure control, increased the incidence of hypertension and caused an increased incidence of dry mouth postoperatively compared with control.     

The use of phenylephrine to obtund oxytocin-induced hypotension and tachycardia during caesarean section

BackgroundOxytocin causes clinically significant hypotension and tachycardia. This study examined whether prior administration of phenylephrine obtunds these unwanted haemodynamic effects.MethodsForty pregnant women undergoing elective caesarean section under spinal anaesthesia were randomised to receive either an intravenous 50 μg bolus of phenylephrine (Group P) or saline (Group S) immediately before oxytocin (3 U over 15 s). Systolic blood pressure, diastolic blood pressure, mean arterial pressure and heart rate were recorded using a continuous non-invasive arterial pressure device. Baseline values were averaged for 20 s post-delivery. Between-group comparisons were made of the mean peak changes in blood pressure and heart rate, and the mean percentage changes from baseline, during the 150 s after oxytocin administration.ResultsThe mean ± SD peak percentage change in systolic blood pressure was −16.9 ± 2% in Group P, and −19.0 ± 1.9% in Group S and the estimated mean difference was 2.1% (95% CI −3.5% to 7.8%; P=0.44); corresponding changes in heart rate were 13.5 ± 2.3% and 14.0 ± 1.5% and the mean estimated difference was 0.5% (95% CI −6.0% to 5%; P=0.87). The mean percentage change from the baseline measurements during the 150 s period of measurement was greater for Group S than Group P: systolic blood pressure −5.9% vs −3.4% (P=0.149); diastolic blood pressure −7.2% vs −1.5% (P=0.014); mean arterial pressure −6.8% vs −1.5% (P=0.007); heart rate 2.1% vs −2.4% (P=0.033).ConclusionIntravenous phenylephrine 50 μg immediately before 3 U oxytocin during elective caesarean section does not prevent maternal hypotension and tachycardia.     

Comparison between colloid preload and crystalloid co-load in cesarean section under spinal anesthesia: a randomized controlled trial

BackgroundHypotension is a common problem during spinal anesthesia for cesarean delivery. Intravenous fluid loading is used to correct preoperative dehydration and reduce the incidence and severity of hypotension. Different fluid regimens have been studied but colloid preload and crystalloid co-load have not been compared.MethodsIn this randomized double-blind study, 210 patients scheduled for elective cesarean section under spinal anesthesia were randomly allocated to receive either 6% hydroxyethyl starch 130/0.4 500 mL before spinal anesthesia (colloid preload) or Ringer’s acetate solution 1000 mL administered rapidly starting with intrathecal injection (crystalloid co-load). Maternal hypotension (systolic blood pressure <80% of baseline or <90 mmHg) and severe hypotension (systolic blood pressure <80 mmHg) were treated with 5 and 10 mg ephedrine boluses, respectively. The primary outcome was the incidence of hypotension. Secondary outcomes included the incidence of severe hypotension, total ephedrine dose, nausea and vomiting and neonatal outcome assessed by Apgar scores and umbilical artery blood gas analysis.ResultsData analysis was performed on 205 patients; 103 in the colloid preload group and 102 in the crystalloid co-load group. There were no significant differences in the incidence of hypotension (52.4% vs. 42.2%; P=0.18) or severe hypotension (15.5% vs. 9.8%; P=0.31) between colloid preload and crystalloid co-load groups, respectively. The median [range] ephedrine dose was 5 [0–45] mg in the colloid preload group and 0 [0–35] mg in the crystalloid co-load group (P=0.065). There were no significant differences in maternal nausea or vomiting or neonatal outcomes between groups.ConclusionThe use of 1000 mL crystalloid co-load has similar effect to 500 mL colloid preload in reducing the incidence of hypotension after spinal anesthesia for elective cesarean delivery. Neither technique can totally prevent hypotension and should be combined with vasopressor use.     

O efeito de epinefrina,norepinefrina e fenilefrina no tratamento da hipotensão pós‐raquianestesia: estudo clínico comparativo

Background and objectivesLimited data are present on safety and efficiency of epinephrine for the prophylaxis and treatment of spinal‐hypotension. This study was conducted to compare the effect of epinephrine with norepinephrine and phenylephrine on the treatment of spinal‐hypotension and ephedrine requirement during cesarean delivery.MethodsOne hundred and sixty parturients with uncomplicated pregnancies undergoing elective cesarean delivery under spinal anesthesia were recruited. They were allocated randomly to receive norepinephrine 5 μg.mL^‐1 (n = 40), epinephrine 5 μg.mL^‐1 (n = 40), phenylephrine 100 μg.mL^‐1 (n = 40) or 0.9% saline infusions (n = 40) immediately after induction of spinal anesthesia. Whenever systolic blood pressure drops to less than 80% of baseline, 5 mg of iv ephedrine was administered as rescue vasopressor. The incidence of hypotension, total number of hypotension episodes, the number of patients requiring ephedrine, the mean amount of ephedrine consumption and side effects were recorded.ResultsThere was no statistically significant difference in incidence of maternal hypotension between groups. The number of patients requiring ephedrine was significantly greater in group saline than in group phenylephrine (p < 0.001). However, it was similar between phenylephrine, norepinephrine, and epinephrine groups. The mean ephedrine consumption was significantly higher in group saline than in norepinephrine, epinephrine, phenylephrine groups (p = 0.001).ConclusionThere is no statistically significant difference in incidence of hypotension and ephedrine consumption during spinal anesthesia for cesarean delivery with the use of epinephrine when compared to norepinephrine or phenylephrine. Epinephrine can be considered as an alternative agent for management of spinal hypotension.     

Anaesthesia mode for caesarean section and mortality in very preterm infants: An epidemiologic study in the EPIPAGE cohort

BackgroundLittle is known about the influence of anaesthesia for caesarean section on outcome in very preterm infants.MethodsA prospective, population-based, cohort study (the EPIPAGE cohort) included all births before 33 weeks in nine French regions in 1997. Of 2360 infants live-born between 27 and 32 weeks, 1338 were delivered by caesarean section with general anaesthesia (n = 711, 53.1%), spinal anaesthesia (n = 419, 31.3%), or epidural anaesthesia (n = 208, 15.6%). Neonatal mortality was compared among these three groups using bi- (according to gestational age and to anaesthetic technique) and multivariate analyses.ResultsNeonatal mortality was 10.1% with general anaesthesia, 12.2% with spinal anaesthesia and 7.7% with epidural anaesthesia. After adjustment for gestational age and characteristics of pregnancy, delivery and neonate, spinal anaesthesia was associated with a higher risk of neonatal death than general anaesthesia (adjusted odds ratio, 1.7; 95% confidence interval 1.1 to 2.6).ConclusionIn this population-based study, spinal anaesthesia was associated with an increased risk of neonatal mortality in very preterm infants compared to general anaesthesia (and epidural anaesthesia), independently from gestational age and characteristics of the pregnancies, deliveries and neonates. Although this multivariate analysis does not prove a causal relationship, the results suggest it could exist, particularly if maternal haemodynamics are poorly controlled. With recent significant change in the conduct of spinal anaesthesia, further studies are needed to investigate potential harmful effects of anaesthesia on very preterm infants delivered by caesarean section.     

A new modality for improving the efficacy of intrathecal injection for cesarean section

BackgroundIntrauterine resuscitation (IUR) is to improve O2 delivery to the placenta and umbilical blood flow, for reversal of foetal hypoxia and acidosis. We evaluated whether maintaining a lateral position after an intrathecal injection of a relatively low dose of hyperbaric bupivacaine and high dose of fentanyl improving the efficacy of spinal anaesthesia, IUR and preventing hypotension during cesarean delivery.MethodsOne hundred and seventy two healthy women undergoing elective cesarean delivery were enrolled in a double blind prospective randomized study. Spinal anesthesia was conducted in the right lateral position which maintained for 6 min for all the patients participated in the study, and then the subjects were turned supine. Patients were randomly allocated to two groups: low-dose spinal bupivacaine (LD) group (n = 86) patients received 6 mg of hyperbaric bupivacaine 0.5% and 15 μg of fentanyl, high-dose spinal bupivacaine (HD) group (n = 86) patients received 10 mg of hyperbaric bupivacaine and 15 μg of fentanyl. The incidence of hypotension and nausea, ephedrine requirement, maximal block height, and Apgar score at 1 and 5 min.ResultsThe authors found significant decrease in MAP in the group that was given the high dose of bupivacaine the incidence of hypotension was 80% but the LD spinal bupivacaine group was hemodynamically stable. The lowest blood pressure, boluses of inj. ephedrine used, or nausea were more significant in the HD group than in LD group. Onset of hypotension was more rapid (8 ± 3 vs. 16 ± 6 min, P < 0.001), and the sensory block level was more cephalad in HD group than in LD group (T2 [C8–T5] vs. T4 [T1–T6], P = 0.001). Apgar scores did not differ between the groups.ConclusionMaintaining the lateral position for 6 min after an intrathecal injection of a relatively low dose of hyperbaric bupivacaine and high dose of fentanyl resulted in improving the efficacy of spinal anaesthesia, IUR by more gradual and higher cephalad sensory block, without an increase in the incidence of maternal hypotension.     

Prospective evaluation of systolic arterial pressure control with a phenylephrine infusion regimen during spinal anaesthesia for caesarean section

BackgroundHypotension and nausea occur frequently during spinal anaesthesia for caesarean section. The aim of this evaluation was to assess systolic arterial pressure control with our routine prophylactic intravenous phenylephrine infusion regimen. We audited a local standard for an incidence of hypotension of ?25% during the first 15 min of anaesthesia.MethodsOne hundred healthy women undergoing elective caesarean section were assessed. Following intravenous preload with 10 mL/kg Hartmann’s solution, 0.5% hyperbaric bupivacaine 2.8 mL combined with diamorphine 400 μg was given intrathecally in the sitting position. Intravenous phenylephrine was then started at 67 μg/min (the maximum rate). Systolic arterial pressure was recorded every 2 min. The infusion was titrated, according to local guidelines, to maintain systolic arterial pressure close to baseline.ResultsThe median dose of phenylephrine given by infusion was 1000 [interquartile range 670–1000] μg, with 51 patients not requiring any change to the infusion rate. Eleven patients (11%, 95% CI 6–19) developed hypotension, defined as a systolic arterial pressure <80% of baseline. A further four patients were given a bolus of phenylephrine for suspected hypotension. The incidence of hypotension or suspected hypotension was therefore 15% (95% CI 9–24). Thirteen patients (13%, 95% CI 7–21) developed nausea. No patient vomited.ConclusionsOur routine phenylephrine infusion regimen was effective at minimizing hypotension and nausea during relatively high-dose spinal anaesthesia. This was achieved with a low intervention rate, in conjunction with a 2-min rather than a 1-min non-invasive blood pressure cycle time and a relatively low volume of intravenous fluid.     

Role of pleth variability index for predicting hypotension after spinal anesthesia for cesarean section

BackgroundHypotension is frequently observed after spinal anesthesia for cesarean section and can be detrimental to both mother and baby. We investigated the role of the pleth variability index for predicting hypotension after spinal anesthesia for cesarean section.MethodsEighty-five parturients undergoing elective cesarean section under spinal anesthesia were enrolled. We recorded pleth variability index and perfusion index before anesthesia, and blood pressure, heart rate and pulse oxygen saturation before and after anesthesia. The association between baseline pleth variability index and perfusion index with hypotension after spinal anesthesia was explored using multivariate analysis.ResultsHypotension occurred in 42 parturients. Baseline pleth variability index was higher in parturients who experienced hypotension than in those who did not (P < 0.05), although there was no difference in baseline perfusion index. The area under the receiver operating characteristic curve was 0.66 for baseline pleth variability index for the prediction of hypotension (P < 0.05). Baseline pleth variability index was significantly related to the incidence of hypotension (P = 0.017), but was not significantly related to the magnitude of the decrease in systolic blood pressure. Baseline perfusion index was not significantly related to the magnitude of the decrease in systolic blood pressure.ConclusionGreater baseline pleth variability index was associated with hypotension after spinal anesthesia for cesarean section, but may not be a clinically useful predictor.     

The effect of adding magnesium sulphate to epidural bupivacaine and fentanyl in elective caesarean section using combined spinal–epidural anaesthesia: a prospective double blind randomised study

BackgroundCombined spinal–epidural anaesthesia is commonly used for elective caesarean section. Intrathecal injection produces rapid onset with minimal doses of local anaesthetic and epidural administration can be used to prolong the block. Our study examined the effects of adding magnesium sulphate to epidural bupivacaine and fentanyl in patients undergoing elective caesarean section using combined spinal–epidural anaesthesia.MethodsWomen ASA physical status I or II at term were recruited. All received 2 mL intrathecal 0.5% hyperbaric bupivacaine, 10 mL epidural 0.25% plain bupivacaine with fentanyl 100 μg, and were randomly allocated to receive either 10 mL of epidural 0.9% sodium chloride or 10 mL epidural 5% magnesium sulphate. The quality of surgical anaesthesia, incidence of hypotension, Apgar scores, intraoperative pain assessment, onset of postoperative pain, sedation scores and side effects were recorded in the postoperative period.ResultsNinety women were recruited. There was no difference in the time taken for the block to reach T4 sensory level, time to reach the highest level of sensory block, time interval between first neuraxial injection and onset of surgery between the groups. Women who received magnesium had greater motor block and muscle relaxation (P < 0.05). Apgar scores were 7 or more in almost all neonates in both groups. There was no significant difference in the incidence of hypotension, nausea and vomiting and duration of motor blockade between the groups. Women who received magnesium showed less shivering and later onset of post operative pain (P < 0.05).ConclusionThe addition of magnesium to epidural bupivacaine and fentanyl in women undergoing elective caesarean section with combined spinal–epidural anaesthesia improved intraoperative conditions and the quality of postoperative analgesia.     

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.     

Serum uric acid as a novel marker for uterine atony and post-spinal vasopressor use during cesarean delivery

IntroductionSerum uric acid is a marker for oxidative stress in preeclampsia. Because oxidative stress can result in diminished uterine contractility and impaired vascular relaxation, we hypothesized that an elevated serum uric acid level in women undergoing neuraxial anesthesia for cesarean delivery would be associated with greater uterine atony, as measured by supplemental uterotonic agent use and blood loss, and less hypotension, as measured by total vasopressor use.MethodsAll records of patients (n = 2527) undergoing cesarean delivery in 2009 were reviewed. Serum uric acid was measured within 24 h of delivery in 509 patients; data from 345 patients with singleton pregnancies undergoing neuraxial anesthesia were analyzed. Demographic data, medical and obstetric history, anesthetic management and peripartum course were evaluated. ANOVA, Chi-square, and multivariate logistic and linear regression analyses were performed.ResultsIncreased serum uric acid correlated positively with preeclampsia and the need for supplemental uterotonic agents (odds ratio 1.53, 95%CI 1.2–2.0, P = 0.002), but not blood loss. The presence of preeclampsia also correlated with greater supplemental uterotonic agent use (P = 0.01). The correlation between serum uric acid and post-spinal vasopressor use (i.e., none, moderate, and high) was of borderline significance (P = 0.05). In patients without diabetes, serum uric acid levels correlated inversely with post-spinal vasopressor use (P = 0.04).ConclusionsElevated serum uric acid in parturients undergoing cesarean delivery with neuraxial anesthesia correlated with increased use of supplemental uterotonic agents and decreased use of post-spinal vasopressors. Further validation of this study is required to determine if serum uric acid in parturients can serve as a reliable predictor for higher and lower occurrences of uterine atony and spinal-induced hypotension, respectively.     

Prévention de l’hypotension induite par la rachianesthésie au cours de la césarienne programmée : coremplissage par HEA 130/0,4 vs sérum salé isotonique

ObjectiveThe aim of this study was to compare the efficacy of HES 130/0.4 coloading compared to normal saline solution for prevention of hypotension during spinal anesthesia for elective caesarean section.Study designProspective, randomized.Patients and methodsOne hundred and twenty ASA I and II patients scheduled for elective caesarean section were recruited. Patients were randomized to receive either 500 mL of HES 130/0.4 (Voluven^®) coloading (Group V) or 500 mL of normal saline solution coloading (Group C). Spinal anesthesia technique and ephedrine administration were standardized in both groups. The primary endpoint was the incidence of maternal hypotension during spinal anesthesia for elective caesarean section.ResultsHypotension occurred in 43 patients in group C and 24 patients in group V (p = 0.001). Ephedrine consumption was significantly lower in group V (P = 0.005). Nausea, vomiting and headache incidence was higher in group C (p = 0.006). Apgar scores and umbilical blood gazes were comparable between groups.ConclusionHES 130/0.4 coload was more effective than normal saline solution to prevent hypotension following spinal anesthesia for elective cesarean section. HES 130/0.4 coload reduced the incidence, the duration of longest hypotension, the need for ephedrine and the adverse maternal effects.     

Las medidas ecográficas de la vena cava inferior no predicen hipotensión arterial postinducción anestésica en pacientes tratados mediante cirugía vascular

IntroductionIntraoperative hypotension (IH) is an independent predictor of mortality. Some experts have suggested that ultrasound measurement of the inferior vena cava (IVC) in spontaneous ventilation can predict IH.ObjectiveTo evaluate the capacity of ultrasound measures of IVC in spontaneous ventilation to predict episodes of IH after anaesthesia induction.Patients and methodsWe studied 55 high-risk cardiac patients undergoing vascular surgery. The maximum (dIVCmax) and minimum (dIVCmin) diameter of the IVC were measured and the collapsibility index CI = (dIVCmax-dIVCmin)/dIVCmax was calculated prior to anaesthesia induction. Three definitions of IH were used: systolic blood pressure (SBP) less than 100 mmHg, mean arterial pressure (MAP) less than 60 mmHg, and a decrease in MAP greater than or equal to 30% compared to baseline.ResultsThere were no significant differences in dIVCmax or in CI between patients presenting IH after anaesthesia induction and those who did not. ROC curves for dIVCmax showed an area under the curve of 0.55 (0.39-0.70), 0.69 (0.48-0.90), and 0.57 (0.42-0.73) and ROC curves for the CI were 0.62 (0.47-0.78), 0.60 (0.41-0.78) and 0.62 (0.47-0.78) for the 3 definitions of IH (<100 mmHg, MAP < 60 mmHg, and MAP ≥30% baseline), respectively.ConclusionsUltrasound measurements of IVC in spontaneous ventilation are not good predictors of IH after anaesthesia induction in these patients. The optimal cut-off points show low specificity and moderate sensitivity for predicting IH.     

General anaesthesia versus combined spinal epidural anaesthesia in the presence of mild to moderate pericardial effusion: A study of volunteers undergoing caesarean section

Study objectiveThis study evaluated the haemodynamic effects of general anaesthesia versus combined spinal epidural anaesthesia in patients undergoing caesarean section in the presence of mild to moderate pericardial effusion.DesignA prospective randomized study.SettingThe study setting included a hospital where a surgical team performed elective caesarean section in the presence of mild to moderate pericardial effusion.Patients and interventionsThirty healthy patients were randomly divided into two groups, general anaesthesia (GA) (group I) and combined spinal epidural (CSE) anaesthesia (group II).Measurements and main resultsHeart rate, central venous pressure, mean arterial blood pressure, and pulmonary capillary wedge pressure were measured 10 min before anaesthesia, after 20 and 30 min of anaesthesia, and 30 min after recovery. Blood loss was significantly lower in group II [465.33 (72.78) ml] as compared to group I [548.20 (22.73) ml]. The pain score in group II was significantly lesser [1.66 (0.72)], than in group I [2.60 (0.73)]. The HR was significantly higher in group I as compared to that in group II at 20 and 30 min after anaesthesia, and 30 min after surgery, being 81.53 (2.72), 94.80 (3.12) and 82.8 (2.85) (beats/min), respectively. However, the CVP was significantly higher in the group I at 20 and 30 min after induction, being 8.40 (0.63) and 7.80 (0.67) (cmH2O) respectively. The MAP was significantly higher in group II than in group I at 20 and 30 min after induction, being 80.86 (1.30) and 81.00 (1.00) (mmHg) respectively. The PCWA was significantly higher in group I compared to group II at 20 and 30 min after induction, being 10.13 (1.35) and 11.80 (0.94) (mmHg), respectively.ConclusionCSE anaesthesia appeared to be more advantageous, in patients undergoing caesarean section with mild to moderate pericardial effusion, with less haemodynamic changes, decreased blood loss, and better postoperative analgesia than general anaesthesia patients.     

Ultrasound-guided spinal anaesthesia in obstetrics: is there an advantage over the landmark technique in patients with easily palpable spines?

BackgroundData are scarce on the advantage of ultrasound-guided spinal anaesthesia in patients with easily identifiable bony landmarks. In this study, we compared the use of ultrasound to the landmark method in patients with no anticipated technical difficulty, presenting for caesarean delivery under spinal anaesthesia.MethodsA total of 150 pregnant women were recruited in this randomized, controlled study. Ultrasound examination and spinal anaesthesia were performed by three anaesthetists with experience in ultrasound-guided neuraxial block. Patients were randomized to either the Ultrasound Group (n = 75) or the Landmark Group (n = 75). In both groups the level of L3–4 or L4–5 was identified by ultrasound (transverse and longitudinal approach) or palpation. The primary outcome was the procedure time, measured from the time of skin puncture by the introducer to the time of viewing cerebrospinal fluid at the hub of the spinal needle. Secondary outcomes were the number of skin punctures, number of passes, and incidence of successful spinal blockade.ResultsThe average procedure time, number of skin punctures and needle passes, were similar in both groups. The number of patients with successful spinal anaesthesia after one puncture was not statistically different between the groups.ConclusionThe present results indicate that when performed by anaesthetists experienced in both ultrasound and landmark techniques, the use of ultrasound does not appear to increase the success rate of spinal anaesthesia, or reduce the procedure time or number of attempts in obstetric patients with easily palpable spines.     

The effect of induced hypertension on neurological outcome in forebrain ischaemia model in rats

IntroductionThe present study investigated the effects of induced hypertension on hippocampal cell death after forebrain ischaemia in rats.Materials and methodsIn this study, forebrain ischaemia was induced in 20 Sprague-Dawley rats by clamping the bilateral common carotid arteries to induce systemic hypotension for 8 min. All rats then underwent reperfusion during which the induced hypertension group (n = 10) received intermittent intravenous injections of phenylephrine (5 μg) to maintain their mean arterial blood pressure at 20 mmHg above baseline for 10 min and the control group (n = 10) did not receive any treatment. In both groups, the numbers of viable and apoptotic neuronal cells in the cornu ammonis 1 (CA1) area of the hippocampus were evaluated 7 days after the induction of ischaemia.ResultsThe mean percentage of viable neuronal cells was higher in the induced hypertension group than in the control group (35% vs. 26%, respectively; p = 0.004), but there was no significant difference in the proportion of apoptotic neuronal cells between the groups (57% vs. 43%, respectively; p = 0.165).ConclusionsInduced hypertension significantly attenuated necrotic cell death in the hippocampal CA1 area, but apoptotic cell death was not affected.     

To estimate the minimum effective dose of oxytocin required to produce adequate uterine tone in women undergoing elective caesarean delivery

To estimate the minimum effective dose of oxytocin required to produce adequate uterine tone in women undergoing elective caesarean delivery under spinal anaesthesia.BackgroundPatients undergoing caesarean delivery are at increased risk of obstetric haemorrhage. Uterine atony has been shown to be most common aetiology (30%) for PPH in patients undergoing caesarean delivery. Use of uterotonic agents decreases the incidence of PPH by approximately 40% when compared with placebo. Oxytocin is the most frequently used uterotonic agent because of less side-effects compared with all other available agents. We did the study to find out the minimal dose of oxytocin required to produce adequate uterine tone (UT) in primigravida women undergoing elective caesarean delivery.MethodsThis randomized double blind study was conducted in ninety full term primigravidas undergoing elective caesarean delivery under spinal anaesthesia. All patients received intravenous bolus of either 0.5, 1, or 2 unit oxytocin followed by infusion of 10 unit/h. UT was assessed by a blinded obstetrician as either adequate or inadequate, and using a five point scale, where 1 = atonic, 2 = partial but inadequate contraction, 3 = adequate contraction, 4 = well contracted and 5 = very well contracted at 2, 3, 6, and 9 min after oxytocin administration. Minimum effective doses of oxytocin were analysed. Oxytocin related side-effects (including hypotension) were recorded.ResultsThere were no significant differences in the prevalence of adequate UT among the study groups at 2 min (86%, 90% and 93% for, 0.5, 1 and 2 unit oxytocin, respectively). The prevalence of nausea and vomiting was significantly higher after 2 unit oxytocin vs 0.5 unit at 1 min (13% vs 3%).ConclusionSmall bolus dosages of oxytocin (0.5–2 unit) result in adequate uterine tone in primigravida women undergoing elective caesarean delivery with minimal effects on haemodynamic parameters and less incidence of nausea and vomiting.