Phenylephrine Requirements Research Articles

Role of prophylactic intravenous calcium in prevention of postspinal hypotension among women with preeclampsia undergoing cesarean delivery: a placebo controlled randomized clinical trial

BackgroundPreeclamptic women, in addition to traditional antihypertensive medications, often receive magnesium supplementation and are at increased risk of postspinal hypotension Postspinal hypotension increases the risk of fetomaternal morbidity. Calcium is a physiological antagonist of magnesium in vascular smooth muscle. Therefore, the study hypothesized that calcium is better suited for preserving systemic vascular resistance and preventing postspinal hypotension during cesarean delivery. ObjectivesThe study aimed to evaluate the effect of prophylactic calcium administration on postspinal hypotension in preeclamptic women receiving magnesium supplementation. MethodsThis prospective, randomized, placebo-controlled, double-blinded, two-arm parallel trial was conducted in preeclamptic women receiving magnesium sulfate supplementation undergoing cesarean delivery. The women were randomized to receive intravenous calcium or a placebo (normal saline) before spinal anesthesia. The study drug (calcium gluconate 500 mg or normal saline) was administered over 15 minutes and ended immediately before spinal anesthesia. The primary outcome measure was the incidence of postspinal hypotension, and secondary outcome measures were postpartum blood loss and maternal and neonatal outcomes. ResultsA total of 100 women (50 each calcium and placebo arm) completed the study. The baseline demographic variables, mean blood pressure and heart rate were comparable. The incidence of postspinal hypotension was significantly lower in the calcium arm compared to the placebo arm (32% vs 60%; Relative risk [95% CI]; 1.87 [1.18–2.97]; P=.007). The mean phenylephrine requirement (5.60±14.59 vs 14.80±22.42 mcg; P=.01) and mephentermine requirement (3.30±5.11 mg vs 5.82±4.97 mg; P=.008) was significantly lower in the calcium group. Furthermore, the calcium group's mean postpartum blood loss was significantly lower (406.90±94.34 vs 472.20±122.49 ml, P=.004). However, the Neonatal Intensive Care Unit admission rate, Apgar score, umbilical artery PH, and maternal serum calcium were comparable. ConclusionProphylactic calcium infusion significantly reduces the incidence of postspinal hypotension during cesarean delivery in preeclamptic women receiving magnesium supplementation. Furthermore, the effect of prophylactic calcium in decreasing postpartum blood loss is encouraging. However, large trials are required to validate the findings of this study.

Pulse oximetry-based perfusion index as a non-invasive indicator of systemic hemodynamics during spinal anesthesia in cesarean delivery

Background & Objectives: Placental perfusion is not autoregulated and is susceptible to effects of spinal anesthesia (SA) induced hypotension. The perfusion index (PI) is a non-invasive marker of peripheral vascular tone, and a higher PI indicates increased risk of hypotension following SA. This study aims to establish preoperative baseline PI in our local population and its correlation with incidence of intraoperative hypotension. Methods: This prospective observational study recruited 35 parturients who underwent elective lower segment cesarean section (LSCS). Preoperatively, baseline heart rate (HR), systolic blood pressure (SBP), mean arterial pressure (MAP) and PI were documented. SA was performed with 8 to 10 mg of injection bupivacaine 0.5% (hyperbaric) at L3–L4 interspace followed by co-loading with 1 L Hartmann solution. Hypotension was defined as SBP less than 80% of baseline or less than 90 mmHg. A bolus of phenylephrine 50 µg was given as rescue medication to treat the hypotension. Intraoperatively, degree of decrease in SBP, MAP and HR, as well as the amount of phenylephrine required was recorded every minute until delivery of the baby and 3 min thereafter. Results: The correlations between parturients’ baseline PI with the degree of decreases in systolic and mean arterial pressure (r = 0.81, P < 0.001 and r = 0.76, P < 0.001, respectively) and phenylephrine requirement (r = 0.761, p < 0.005) were recorded. This study identified that the patients with cut-off PI value of 3.2 were at higher risk for SA induced hypotension with a sensitivity of 85.9% and a specificity of 87.5% (P = 0.001). Conclusion: The patients with baseline cut-off perfusion index value of more than 3.2 were at higher risk for spinal anesthesia induced hypotension in elective cesarean section. Abbreviations: CO - cardiac output; LSCS - lower segment cesarean section MAP - mean arterial pressure; PI - perfusion index; SA - spinal anesthesia Keywords: Hypotension; Pulse Oximeter; Perfusion Index; Spinal Anesthesia; Cesarean section; Citation: Manap NSA, Zaini RHM, Shukeri WFWM, Omar SC, Abu Bakar MZ, Seevaunnamtum P. Pulse oximetry-based perfusion index as a non-invasive indicator of systemic hemodynamics during spinal anesthesia in cesarean delivery. Anaesth. pain intensive care 2024;28(5):927−932; DOI: 10.35975/apic.v28i5.2570 Received: July 23, 2024; Reviewed: September 02, 2024; Accepted: September 10, 2024

Effect of intravenous palonosetron on hypotension induced by spinal anesthesia for cesarean section: A randomized controlled trial.

The aim of this study was to evaluate the impact of intravenous palonosetron compared to ondansetron on hypotension induced by spinal anesthesia in women undergoing cesarean section. Fifty-four women scheduled for elective cesarean section were, randomly allocated to ondansetron group (n = 27) or palonosetron group (n = 27). Ten minutes prior to the administration of spinal anesthesia, participants received an intravenous injection of either ondansetron or palonosetron. A prophylactic phenylephrine infusion was initiated immediately following the intrathecal administration of bupivacaine and fentanyl. The infusion rate was titrated to maintain adequate blood pressure until the time of fetal delivery. The primary outcome was total dose of phenylephrine administered. The secondary outcomes were nausea or vomiting, the need for rescue antiemetics, hypotension, bradycardia, and shivering. Complete response rate, defined as the absence of postoperative nausea and vomiting and no need for additional antiemetics, were assessed for up to 24 hours post-surgery. No significant differences were observed in the total dose of phenylephrine used between the ondansetron and palonosetron groups (387.5 μg [interquartile range, 291.3-507.8 μg versus 428.0 μg [interquartile range, 305.0-507.0 μg], P = 0.42). Complete response rates also showed no significant differences between the groups both within two hours post-spinal anesthesia (88.9% in the ondansetron group versus 100% in the palonosetron group; P = 0.24) and at 24 hours post-surgery (81.5% in the ondansetron group versus 88.8% in the palonosetron group; P = 0.7). In addition, there was no difference in other secondary outcomes. Prophylactic administration of palonosetron did not demonstrate a superior effect over ondansetron in mitigating hemodynamic changes or reducing phenylephrine requirements in patients undergoing spinal anesthesia with bupivacaine and fentanyl for cesarean section.

Comparison of hemodynamic changes in normotensive and preeclamptic parturients undergoing cesarean section under spinal anesthesia: A prospective observational study

Abstract Background and Aims: The safety of subarachnoid block (SAB) was established in preeclamptic parturients, but most of studies are of low quality. The study aimed to compare the hemodynamic parameters, phenylephrine requirement, and the neonatal outcome between normotensive and preeclamptic parturients undergoing cesarean section. Methods: This prospective observational study was conducted in 100 parturients, aged between 18 and 35 years, American Society of Anesthesiologists II/III scheduled for elective cesarean section under SAB. The heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean blood pressure (MBP) were recorded at the baseline, before SAB, and every 2 min till 30 min and then every 5 min till the end of the surgery. Phenylephrine was administered in a bolus of 50 μg when the MBP falls by 20% from the baseline. Neonatal outcomes were measured with the umbilical artery pH and APGAR scores at 1 and 5 min. The Statistical Package for the Social Science (SPSS) 26 was used for analysis. Results: The percentage fall in DBP and mean arterial BP from baseline was statistically significant between groups (26.83% ± 9.58% vs. 20.06% ± 14.17% and 24.90% ± 6.49% vs. 20.11% ± 9.75%). The mean requirement of phenylephrine was higher in the normotensive group than the preeclamptic (95.16 ± 41.54, 68.42 ± 31.14) (P < 0.001). The umbilical artery pH and APGAR scores at 1 and 5 min were comparable in both the groups. Conclusion: The incidence of hypotension was less in preeclamptic and required less phenylephrine compared to normotensives, with comparable neonatal parameters in parturients undergoing cesarean section under spinal anesthesia.

Role of Prophylactic Intramuscular Glycopyrrolate in Preventing Hypotension and Bradycardia in Patients Undergoing Elective Lower Limb Surgeries under Spinal Anaesthesia: A Randomised Placebo-controlled Study

Introduction: Spinal anaesthesia is an extensively used anaesthetic technique for infraumbilical surgeries. Despite its many advantages, hypotension and bradycardia are two common complications. The incidence of bradycardia following spinal anaesthesia is higher in young adults. Although a few previous studies have observed that intramuscular glycopyrrolate is effective in preventing spinal-induced bradycardia and hypotension in elderly and parturient patients, there is a lack of reported studies in the young population. Aim: To evaluate the role of intramuscular glycopyrrolate in the prevention of bradycardia and hypotension in adult patients undergoing lower limb surgeries. Materials and Methods: A randomised, parallel-group, doubleblind, placebo-controlled study was conducted in the Department of Anaesthesiology at Calcutta National Medical College, Kolkata, West Bengal, India. The duration of the study was 15 months, from July 2021 to September 2022. A total of 60 patients aged 18-45 years, of either sex, with American Society of Anaesthesiologists (ASA) physical status I and II, undergoing elective lower limb surgeries under spinal anaesthesia. The patients were randomised into two groups: group G received intramuscular glycopyrrolate 1 mL (0.2 mg) and group N received intramuscular normal saline 1 mL 15 minutes prior to spinal anaesthesia. Hyperbaric bupivacaine (0.5%) 3 mL and fentanyl (25 mcg) 0.5 mL were injected intrathecally. Haemodynamic parameters were monitored. All data were analysed using appropriate statistical tests. A p-value of <0.05 was considered statistically significant. Changes in Heart Rate (HR) were considered the primary outcome variable. The secondary outcome variables were changes in Mean Arterial Pressure (MAP), incidence of bradycardia and hypotension, phenylephrine requirement, and incidence of dry mouth. Results: The mean age of the study participants of group G and group N was 34.17 years and 33.63 years. The two groups were comparable in terms of demographic profile. In comparison to group N, patients in group G showed a significantly higher HR throughout the intraoperative period (p<0.001) and at 60 minutes in the postoperative period. The incidence of hypotension was significantly higher in group N (53.33%) compared to group G (3.33%, p<0.001), and the MAP was lower in group N compared to group G in the intraoperative period. The number of patients requiring phenylephrine was also higher in group N (53.33%) compared to those in group G (3.33%). Conclusion: Prophylactic use of intramuscular glycopyrrolate can maintain stable haemodynamics in patients undergoing lower limb surgeries under spinal anaesthesia. It can maintain a higher HR and reduces the incidence of hypotension following spinal anaesthesia.

Effect of combined intraoperative use of the Nociception Level (NOL) and bispectral (BIS) indexes on desflurane administration

BackgroundCurrently, nociception monitors are not part of standard anaesthesia care. We investigated whether combined intraoperative nociception (NOL index) and anaesthesia (BIS index) monitoring during general anaesthesia would reduce anaesthetics consumption and enhance intraoperative safety and postoperative recovery when compared to standard of care monitoring (SOC). MethodsIn this randomised study, we included 60 patients undergoing colonic surgery under desflurane/remifentanil anaesthesia and epidural analgesia. Patients received either standard monitoring or combined BIS + NOL index monitoring. In the monitored group, remifentanil infusion was titrated to achieve a NOL index below 20. Desflurane was adjusted to BIS values (45–55). In the SOC group, remifentanil and desflurane were titrated on vital signs and MAC. The primary outcome was intraoperative desflurane consumption. ResultsFifty-five patients were analysed. Desflurane administration was reduced in the monitored group from 0.25 ± 0.05 to 0.20 ± 0.06 mL kg−1 h−1 (p < 0.001). The cumulative time with a BIS under 40 was significantly higher in the SOC group with a median time of 12.6 min (95% CI: 0.6–80.0) versus 2.0 min (95% CI: 0.3–5.83) (p = 0.023). Time for extubation was significantly shorter in the monitored group: 4.4 min (95% CI: 2.4–4.9) versus 6.28 min (95% IC: 5.0–8.2) (p = 0.003). We observed no differences in remifentanil or phenylephrine requirements during anaesthesia or in postoperative outcome measures, such as postoperative pain, opioid consumption, neurocognitive recovery. ConclusionCombined intraoperative monitoring of anaesthesia and nociception during colonic surgery resulted in less desflurane consumption and quicker extubation time compared to standard clinical care monitoring.

Comparison of the Hemodynamic Changes in Normotensive and Severe Preeclamptic Pregnant Woman Posted For Cesarean Section under Spinal Anaesthesia

Background: Spinal anesthesia is widely considered a technique of choice for cesarean delivery. But due to fear of sudden and extensive sympathetic blockade, spinal anesthesia may not be considered safe in severe preeclampsia. Objectives: The aim of the present study was to compare the heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), incidence of hypotension, phenyl ephrine requirement and neonatal outcome between normotensive and severe pre-eclamptic women undergoing cesarean section under spinal anesthesia. Material and Methods: A total of 35 severe pre-eclamptic (BP &gt; 160/110 mmHg) 3(Group A) and 35 healthy parturients (group B), meeting the inclusion criteria were included in the study. After preloading with 10 ml/kg of ringer lactate (RL) solution spinal anesthesia was administered with 12.5 mg of hyper baric bupivacaine. Heart rate and blood pressure were recorded before spinal anesthesia and thereafter at 3 minute intervals upto 60 minutes. Hypotension was defined as MAP LESS,THAN 30% of the baseline or a decrease in SBP to LESS THAN 100 mm Hg over the same time interval and was treated with 50 mcg phenylephrine intravenously (i.v). Apgar score was noted 1 and 5 min after birth. Results: The incidence rate of hypotension among the preeclamptic patients was lower than that of the healthy parturients (55.6% vs. 34.1%). The minimum SBP, DBP, and MAP recorded were lower in normotensive, and the difference between two groups was statistically significant. The mean phenylephrine requirement in the normotensive group (151.1 ± 70) was significantly greater (P LESS THAN 0.0001) than that of pre-eclamptic group (48.3 ± 35). The total doses of IV Phenylephrine for treating hypotension were significantly lower among the preeclamptic patients (72 mcg in preeclamptic patients versus 188 mcg in normotensive patients) (P LESS THAN 0.05). There was no statistical difference in the neonatal outcome and Apgar score in the study groups. Conclusion: Pre-eclamptics experienced less hypotension following subarachnoid block (SAB) than normotensives and required less phenylephrine with comparable fetal Apgar scores.

Comparison of the Hemodynamic Changes in Normotensive and Severe Preeclamptic Pregnant Woman Posted For Cesarean Section under Spinal Anaesthesia

Background: Spinal anesthesia is widely considered a technique of choice for cesarean delivery. But due to fear of sudden and extensive sympathetic blockade, spinal anesthesia may not be considered safe in severe preeclampsia. Objectives: The aim of the present study was to compare the heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), incidence of hypotension, phenyl ephrine requirement and neonatal outcome between normotensive and severe pre-eclamptic women undergoing cesarean section under spinal anesthesia. Material and Methods: A total of 35 severe pre-eclamptic (BP &gt; 160/110 mmHg) 3(Group A) and 35 healthy parturients (group B), meeting the inclusion criteria were included in the study. After preloading with 10 ml/kg of ringer lactate (RL) solution spinal anesthesia was administered with 12.5 mg of hyper baric bupivacaine. Heart rate and blood pressure were recorded before spinal anesthesia and thereafter at 3 minute intervals upto 60 minutes. Hypotension was defined as MAP LESS,THAN 30% of the baseline or a decrease in SBP to LESS THAN 100 mm Hg over the same time interval and was treated with 50 mcg phenylephrine intravenously (i.v). Apgar score was noted 1 and 5 min after birth. Results: The incidence rate of hypotension among the preeclamptic patients was lower than that of the healthy parturients (55.6% vs. 34.1%). The minimum SBP, DBP, and MAP recorded were lower in normotensive, and the difference between two groups was statistically significant. The mean phenylephrine requirement in the normotensive group (151.1 ± 70) was significantly greater (P LESS THAN 0.0001) than that of pre-eclamptic group (48.3 ± 35). The total doses of IV Phenylephrine for treating hypotension were significantly lower among the preeclamptic patients (72 mcg in preeclamptic patients versus 188 mcg in normotensive patients) (P LESS THAN 0.05). There was no statistical difference in the neonatal outcome and Apgar score in the study groups. Conclusion: Pre-eclamptics experienced less hypotension following subarachnoid block (SAB) than normotensives and required less phenylephrine with comparable fetal Apgar scores.

Maternal heart rate responses in the supine position and their relationship with hypotension and phenylephrine requirements during elective caesarean delivery using spinal anaesthesia: An observational study

BackgroundHypotension is the main side effect of spinal anaesthesia (SA) for elective caesarean delivery (CD). An increased in heart rate in response to inferior vena cava (IVC) compression has been reported to be predictive of hypotension and vasopressor requirements in this setting. The objective of the study was to evaluate the prevalence of an increase in heart rate in response to IVC compression and its potential effect on hypotension and phenylephrine requirements. MethodsHealthy parturients scheduled for elective CD under SA were preoperatively investigated for a positive supine stress test (SST). It was defined as an increase in heart rate (HR) > 10 beats/min after 5 min of supine position. A crystalloid coload and prophylactic phenylephrine infusion were systematically used to maintain systolic arterial pressure (SAP) between 90–100% of baseline. Hypotension was defined as SAP < 80% of baseline. ResultsAmong 100 women, 26% had a positive SST. There was no significant difference in the incidence of hypotension: 38% versus 24.3% (p = 0.17) in women with positive SST or without, respectively. The cumulative dose of phenylephrine (450 µg [325–625] versus 350 µg [250–500], p = 0.09) was not significantly different between the two groups. Incidences of reactive hypertension, bradycardia, nausea or vomiting and neonatal outcomes were comparable. ConclusionsA positive SST to IVC compression was found in a quarter of term women scheduled for elective CD under SA. This condition has no significant impact on hypotension and phenylephrine requirements when using a crystalloid coload and a phenylephrine infusion targeted at maintaining SAP close to baseline.

Colloid preloading versus crystalloid preloading to prevent hypotension after spinal anesthesia for cesarean delivery: A protocol for systematic review and meta-analysis.

Background:Maternal hypotension is the most frequent complication of spinal anesthesia for cesarean delivery, and intravenous fluid preloading is a preventive measure. We aimed to assess the efficacy of colloids versus crystalloids for preloading to reduce the incidence of spinal anesthesia-induced hypotension and vasopressor requirement in healthy parturients during elective cesarean delivery.Methods:We searched the Cochrane Library, MEDLINE and EMBASE to identify all studies published to June, 2019, through OVID and PubMed. We included randomized controlled trials, comparing colloid preloading with crystalloid preloading in women having spinal anesthesia for cesarean delivery. Primary outcomes were the incidence of hypotension and vasopressor requirement. Secondary outcomes included nausea and/or vomiting, neonatal Apgar score, neonatal umbilical blood pH. We used standardized mean differences for expressing continuous outcomes and risk ratios for dichotomous outcomes. Random-effect model was performed to estimate the pooled risk ratios and standardized mean differences.Results:Thirty-three randomized controlled trials contributed data for this meta-analysis. Fewer women experienced hypotension in the colloid group compared with the crystalloid group (risk ratio: 0.72, 95% confidence interval: 0.63–0.82; 2566 women, 32 studies; P < .00001). The total ephedrine dose required was significantly lower with colloid preloading (standardized mean difference: −0.37, 95% CI: −0.64 to −0.09; 1472 women, 19 studies; P = .009). Colloid preloading was also associated with fewer phenylephrine requirement compared with crystalloid preloading (standardized mean difference: -0.54, 95% CI: -0.82 to -0.25; 169 women; P = .0002). The incidence of nausea and/or vomiting was significantly reduced with colloid preloading (risk ratio: 0.72, 95% CI: 0.55–0.95; 1601 women, 20 studies; P = .02). However, the incidence of 1-minute Apgar score < 7, umbilical artery pH < 7.2 and umbilical vein pH < 7.2 were not statistically different between groups.Conclusions:Colloid preloading is superior to crystalloid preloading in reducing the incidence of hypotension induced by spinal anesthesia and vasopressor requirement in the healthy parturients undergoing elective cesarean delivery.The PROSPERO registration number: CRD42018096402.

Effect of ondansetron on spinal induced hypotension in caesarean deliveries

Background: Spinal anesthesia is the preferred technique of anesthesia employed for caesarean sections. However, it is very often complicated by hypotension. Different drugs and techniques have been used to prevent the hypotension induced by spinal anesthesia. In this study, the effect of ondansetron on the prevention of hypotension after spinal anesthesia was evaluated.&#x0D; Objectives: To determine the effect of prophylactic ondansetron on prevention of spinal induced hypotension in elective caesarean section.&#x0D; Methodology: Eighty-six parturients planned for elective caesarean deliveries were randomized into two groups of 43 each. Group O received Ondansetron 4 mg (4 ml) and Group S received Normal Saline (4 ml) intravenously 10 minutes prior to spinal anesthesia. Blood pressure, heart rate, phenylephrine requirements, occurrence of nausea and vomiting and APGAR scores of neonates were compared between the groups. Hemodynamic data was analyzed using Student’s t-test for intergroup comparison and ANOVA was used for intragroup comparison. Categorical data was analyzed using Pearson Chi-Square test. For all determinants, p-value &lt;0.05 was considered significant.&#x0D; Results: Occurrence of hypotension in Group O (20.9 %) was significantly lower than in Group S (72.1%) (p &lt; 0.05). The mean arterial pressure was significantly higher in Group O at 2, 6, 8, 12 and 14 minutes (p &lt; 0.05). The use of phenylephrine (37.21 mcg vs. 146.51 mcg, p &lt; 0.05) and occurrence of nausea (11.6%, vs. 41.9% p &lt; 0.002) was significantly lower in ondansetron group.&#x0D; Conclusion: Ondansetron is effective in preventing spinal induced hypotension in elective caesarean sections.

Distribution of Ventilation in Pneumoperitoneum: Comment.

We read with great interest a very informative and well-conducted study by Shono et al. titled “Positive End-expiratory Pressure and Distribution of Ventilation in Pneumoperitoneum Combined with Steep Trendelenburg Position” published in the Journal.1 The study has objectively shown that application of positive end-expiratory pressure (PEEP) of 15 cm H2O resulted in more homogeneous ventilation and favorable pulmonary physiologic effects during robot-assisted laparoscopic prostatectomy, but did not improve postoperative lung function. Whereas that authors have focused on the beneficial pulmonary effects of high PEEP values, the article would benefit readers considerably if the authors could address its potential ill effects on some other organ systems.In this regard we wish to highlight our concern regarding application of high PEEP on intracranial pressure (ICP) in patients given a steep Trendelenberg position. It is known that ICP rises rapidly with pneumoperitoneum and this increase is more pronounced due to the effects of gravity in patients assuming the head-down Trendelenburg position.2,3 Increased intraabdominal pressure displaces the diaphragm cranially, narrowing the inferior vena cava and decreasing venous return which, in turn, increases the ICP.3 The high intrathoracic pressures due to positive pressure ventilation and high intraabdominal pressure due to pneumoperitoneum cause a triple compartment syndrome because of an increase in ICP. In susceptible populations such as patients with head injuries or patients who have undiagnosed intracranial pathology, neurologic deterioration could be a concern. Clinically, even minor adverse effects of raised ICP may present in different ways.4 In a study by Cooke et al., headache and nausea were found to be significantly higher after laparoscopic abdominal surgery, possibly due to raised ICP.4Shono et al. have reported that phenylephrine requirement in the high PEEP group was significantly greater than in the normal PEEP group. For maintenance of cerebral perfusion pressure, a higher mean arterial pressure should have been targeted in view of the raised ICP. The authors have reported a raised arterial carbon dioxide of 49 ± 5 mm Hg which may also have detrimental effect on the ICP. Adjusting the respiratory rate to normalize the end tidal carbon dioxide could have been considered in the study design. In susceptible individuals, surgeries lasting 484 ± 81 min with a persistently high ICP resulting from a high PEEP of 15 cm H2O could result in a greater incidence of complications. These complications should be investigated before we can recommend universal application of a high PEEP in all patients. Prospective authors planning similar studies could consider adding incidence of adverse effects on ICP or intraocular pressure as one of their secondary objectives; otherwise, they could include these concerns as limitations of their study.The authors declare no competing interests.

Comparison of Two Methods of Anesthesia Using Patient State Index: Propofol Versus Sevoflurane During Interventional Neuroradiology Procedure.

BackgroundOver the past few decades, interventional neuroradiology (INR) has been a rapidly growing and evolving area of neurosurgery. Sevoflurane and propofol are both suitable anesthetics for INR procedures. While the depth of anesthesia is widely monitored, few studies have examined the patient state index (PSI) during clinical neuroanesthesia.ObjectivesThis study aimed to investigate the differences in PSI values and in hemodynamic variables between sevoflurane anesthetic and propofol anesthetic during INR procedures.MethodsWe reviewed the medical charts of the patients who underwent embolization of a non-ruptured intracranial aneurysm by a single operator at a single university hospital from May 2013 to December 2014. Sixty-five patients were included and divided into two groups: S group (sevoflurane anesthesia, n = 33) vs. P group (propofol anesthesia, n = 32). The PSI values, hemodynamic variables, and use of hemodynamic drugs between two groups were analyzed.ResultsThere were significant differences between the PSI values obtained through different perioperative stages in the two groups (P < 0.0001). During the procedure, the PSI values were significantly lower in the P group than in the S group (P = 0.000). The P group patients had a more prolonged extubation time (P = 0.005) and more phenylephrine requirement than the S group patients (P = 0.007). More anti-hypertensive drugs were administered to the patients in the S group during extubation (P = 0.0197).ConclusionsThe PSI can be used to detect changes in anesthetics concentration and in the depth of anesthesia during INR procedures. Although the extubation was faster under sevoflurane anesthetic, propofol anesthetic showed rather smoother recovery.

Left Lateral Table Tilt for Elective Cesarean Delivery under Spinal Anesthesia Has No Effect on Neonatal Acid-Base Status: A Randomized Controlled Trial.

Current recommendations for women undergoing cesarean delivery include 15° left tilt for uterine displacement to prevent aortocaval compression, although this degree of tilt is practically never achieved. We hypothesized that under contemporary clinical practice, including a crystalloid coload and phenylephrine infusion targeted at maintaining baseline systolic blood pressure, there would be no effect of maternal position on neonatal acid base status in women undergoing elective cesarean delivery with spinal anesthesia. Healthy women undergoing elective cesarean delivery were randomized (nonblinded) to supine horizontal (supine, n = 50) or 15° left tilt of the surgical table (tilt, n = 50) after spinal anesthesia (hyperbaric bupivacaine 12 mg, fentanyl 15 μg, preservative-free morphine 150 μg). Lactated Ringer's 10 ml/kg and a phenylephrine infusion titrated to 100% baseline systolic blood pressure were initiated with intrathecal injection. The primary outcome was umbilical artery base excess. There were no differences in umbilical artery base excess or pH between groups. The mean umbilical artery base excess (± SD) was -0.5 mM (± 1.6) in the supine group (n = 50) versus -0.6 mM (± 1.5) in the tilt group (n = 47) (P = 0.64). During 15 min after spinal anesthesia, mean phenylephrine requirement was greater (P = 0.002), and mean cardiac output was lower (P = 0.014) in the supine group. Maternal supine position during elective cesarean delivery with spinal anesthesia in healthy term women does not impair neonatal acid-base status compared to 15° left tilt, when maternal systolic blood pressure is maintained with a coload and phenylephrine infusion. These findings may not be generalized to emergency situations or nonreassuring fetal status.

The Influence of Body Mass Index on Sensorimotor Block and Vasopressor Requirement During Spinal Anesthesia for Elective Cesarean Delivery.

It has been suggested that the dose requirement for spinal anesthesia (SA) is lower in obese patients for cesarean delivery (CD). In this prospective, observational, noninferiority study, we tested the hypothesis that obesity would not have a clinically important effect on vasopressor requirements or block height. Two groups of 25 parturients, group O (body mass index [BMI] >40 kg/m) and group N (BMI <32 kg/m) requiring elective CD were recruited. All patients received 10 mg intrathecal hyperbaric bupivacaine coadministered with 10 μg fentanyl. Dermatomal levels were assessed at 5 and 25 minutes after SA, and at completion of surgery, using light touch and cold sensation in response to ethyl chloride. The primary outcomes were phenylephrine requirement in the first 30 minutes after SA, and maximum block height, measured by the sensation of touch and cold. Secondary outcomes were total phenylephrine dose required, changes in hand grip strength, and peak flow rate. There were no significant between-group differences in median block height as assessed by touch at 5 or 25 minutes or by temperature at 5 minutes. At 25 minutes, there was a 2-dermatome difference in median block height for loss of temperature sensation between group O and group N (T2 vs T4, 95% confidence interval [CI] of the difference in medians 0-2 dermatomes). No blocks extended to cervical dermatomes. The median (range) phenylephrine dose for the first 30 minutes was 150 µg (0-900 µg), and 100 µg (0-1250 µg) in group N and group O, respectively. The 95% CI for the difference between the 2 median doses was -150 µg to 100 µg. There were no differences in median percentage reductions in peak flow rate or median hand grip strength after SA. Mean surgical time was longer in group O than in group N (49.1 vs 39.4 min, 95% CI difference 1.7-17.7 min). The mean time for recovery of touch sensation to T10 was longer in group O (152 vs 132 min, 95% CI difference 3.8-36.2 min). No analgesic supplementation was required. Only a minor increase in block height as assessed by temperature occurred in group O at 25 minutes. Vasopressor requirements during the first 30 minutes of SA were equivalent. Time for regression of SA block level was longer in the group O, which may be beneficial considering the longer surgical time. A dose of spinal bupivacaine 10 mg for single-shot SA should not be reduced in morbidly obese parturients.

Ondansetron Does Not Attenuate Hemodynamic Changes in Patients Undergoing Elective Cesarean Delivery Using Subarachnoid Anesthesia

Hypotension is the most common complication after subarachnoid anesthesia for cesarean delivery. Several therapeutic and preventive measures are used to attenuate this side effect. Serotonin receptor-blocking drugs have been suggested as one such approach. We sought to determine whether prophylactically administered intravenous ondansetron could attenuate hypotension in patients undergoing elective cesarean delivery performed under subarachnoid anesthesia. Eighty-six patients undergoing elective cesarean delivery were recruited and randomly allocated to receive either 8 mg intravenous ondansetron (group O; n = 44) or placebo (group P; n = 42) in a prospective double-blind design. Systolic blood pressure (SBP), mean arterial pressure (MAP), diastolic blood pressure (DBP), and heart rate (HR) were measured at baseline and at 3-minute intervals from the time of initiation of subarachnoid anesthesia until delivery. Ondansetron effect on hemodynamics (SBP, DBP, MAP, and HR) was quantified and analyzed using a linear mixed effect model. We did not find differences in SBP (P = 0.78), MAP (P = 0.89), DBP (P = 0.82), or HR (P = 0.18) between the 2 groups during the study period. Phenylephrine requirements to treat hypotension were 350 μg (175-700 μg) in group O and 450 μg (300-700 μg) in group P (P = 0.30). The incidence of pruritus was 63% (n = 28 of 44) in group O and 56% (n = 23 of 42) in group P (difference, 0.08 [95% confidence interval, -0.23 to 0.41], P = 0.59). No difference in the incidence of nausea and vomiting or sensory level was found. Ondansetron premedication does not attenuate hemodynamic changes after subarachnoid anesthesia nor does it reduce the amount of vasopressor use, pruritus, or nausea and vomiting.

6% Hydroxyethyl starch (130/0.4) vs Ringer's lactate preloading before spinal anaesthesia for Caesarean delivery: the randomized, double-blind, multicentre CAESAR trial

Vasopressor administration is recommended to prevent hypotension during spinal anaesthesia (SA) for elective Caesarean delivery. We aimed to test the superior efficacy and ensure safety of a hydroxyethyl starch (HES) vs a Ringer's lactate (RL) preloading, when combined with a phenylephrine-based prophylaxis. A total of 167 healthy parturients undergoing elective Caesarean delivery under SA were included in this multicentre, randomized, double-blind study. Patients received 500 ml of 6% HES (130/0.4)+500 ml of RL (HES group) or 1000 ml of RL (RL group) i.v. before SA. After SA, i.v. phenylephrine boluses were titrated when systolic arterial pressure (SAP) was below 95% of baseline. The primary outcome was the incidence of maternal hypotension (SAP <80% of baseline). The incidence of both hypotension and symptomatic hypotension (i.e. with dizziness, nausea/vomiting, or both) was significantly lower in the HES group vs the RL group: 36.6% vs 55.3% (one-sided P=0.025) and 3.7% vs 14.1%. There was no significant difference in total phenylephrine requirements [median (range): 350 (50-1800) vs 350 (50-1250) µg]. The decrease in maternal haemoglobin value the day after surgery was similar in the two groups [1.2 (1.0) vs 1.0 (0.9) g dl(-1)]. There was no detectable placental transfer of HES in six umbilical cord blood samples analysed in the HES group. Neonatal outcomes were comparable between the groups. Compared with a pure RL preloading, a mixed HES-RL preloading significantly improved prevention of both hypotension and symptomatic hypotension based on early phenylephrine bolus administration and did not induce adverse effects. NCT00694343 (http://clinicaltrials.gov).

Comparison of hemodynamic response and vasopressor requirement following spinal anaesthesia between normotensive and severe preeclamptic women undergoing caesarean section: A prospective study

Background: Spinal anesthesia is the technique of choice in cesarean sections, but it is not widely accepted in severe pre-eclampsia due to fear of sudden and extensive sympathetic blockade. The aim of the present study was to compare the heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), phenyl ephrine requirement, and neonatal outcome between normotensive and severe pre-eclamptic women undergoing cesarean section under spinal anesthesia. Materials and Methods: A total of 30 healthy (group 1) and 30 severe pre-eclamptic (BP > 160/110 mmHg) parturients (group 2) above 18 years of age, meeting inclusion criteria undergoing elective cesarean section, were included in the study. After preloading with 10 ml/kg of ringer lactate solution spinal anesthesia was administered with 12.5 mg of hyper baric bupivacaine. Also, SBP, DBP, MAP, and HR were recorded before spinal anesthesia and then at every 2-min interval after spinal block for the first 30 min and thereafter every 5 min until completion of surgery. Phenylephrine was administered in 50 μg bolus dose when MAP decreased below 30% of base line. Apgar score was noted 1 and 5 min after birth. Results: The minimum SBP, DBP, and MAP recorded were lower in normotensive, and the difference between two groups was statistically significant. The mean phenylephrine requirement in the normotensive group (151.1 ± 70) was significantly greater (P < 0.0001) than that of pre-eclamptic group (48.3 ± 35). Apgar scores at 1 and 5 min after birth were comparable in both the groups.Conclusion: Pre-eclamptics experienced less hypotension following subarachnoid block (SAB) than normotensives and required less phenylephrine with comparable fetal Apgar scores.

Could ephedrine replace meperidine for prevention of shivering in women undergoing Cesarean Section under spinal anesthesia? A randomized study

PurposeTo compare possible unlabeled effect of ephedrine, as shivering prophylaxis, with meperidine during spinal anesthesia for Cesarean Section.MethodsAfter institutional ethical committee approval, 96 parturients scheduled for elective cesarean delivery under spinal anesthesia were randomly allocated according to shivering prophylaxis to receive either 15 mg meperidine (group M, n = 48) or 6 mg ephedrine (group E, n = 48) intravenously before spinal block. Incidence and intensity of shivering as well as side effects of either drug were assessed.ResultsThe incidence shivering in meperidine and ephedrine groups in women undergoing Cesarean Section under spinal anesthesia was comparable (27%, 29% respectively, P = 0.06). Also, intensity of shivering was not different between two groups. Moreover, phenylephrine requirement and incidence of nausea and vomiting were significantly less in ephedrine group (121 ± 2.2% and 4.1% respectively) relative to meperidine group (168 ± 3.2% and 16.6% respectively).ConclusionThe prophylactic use of a low dose ephedrine is effective as meperidine for shivering prophylaxis in women undergoing Cesarean Section under spinal anesthesia as meperidine. Moreover, it is associated with less hypotension, nausea and vomiting.

The Effect of Maternal and Fetal β2-Adrenoceptor and Nitric Oxide Synthase Genotype on Vasopressor Requirement and Fetal Acid-Base Status During Spinal Anesthesia for Cesarean Delivery

Previous work demonstrated that maternal haplotypes of the β₂-adrenoceptor gene (ADRB2) influence ephedrine requirements during cesarean delivery. The use of ephedrine versus a pure α-adrenergic agonist such as phenylephrine has been associated with lower umbilical artery (UA) pH, thought to be secondary to increased fetal metabolism. There are no data evaluating the effect of fetal/neonatal genotypes on the metabolic response to maternally administered vasopressors. We hypothesized that neonatal ADRB2 genotype would affect the extent of neonatal acidemia. We also examined the effect of maternal ADRB2 and the endothelial nitric oxide synthase gene (NOS3) on ephedrine and phenylephrine requirements for treatment of maternal hypotension. The study was performed on 104 Chinese women scheduled for cesarean delivery under spinal anesthesia who were participating in a double-blind randomized clinical trial evaluating the maternal and neonatal effects of ephedrine versus phenylephrine infusions. Blood samples were drawn from the UA, umbilical vein, and maternal radial artery to measure blood gas values and lactate, ephedrine, and phenylephrine concentrations, and to determine maternal and neonatal genotype at nonsynonymous single nucleotide polymorphisms at codons 16 (rs1042713) and 27 (rs1042714) of ADRB2 and codon 298 (rs1799983) of NOS. Clinical variables (UA pH, UA lactate, and dose of vasopressors) among genotypes were compared, and regression models were created to assess the effect of genotype on vasopressor dose and fetal acid-base status. Maternal ADRB2 genotype did not affect the ephedrine dose. Neonatal genotype at codon 16 influenced fetal acid-base status. UA pH was higher in Arg16 homozygous neonates (7.31 ± 0.03 in p.16Arg/Arg vs. 7.25 ± 0.11 in p.16 Arg/Gly and p.16 Gly/Gly; P < 0.001, 95%confidence interval (CI) of difference 0.03 ~ 0.09) and UA lactate was lower (2.67 mmol/L ± 0.99 in p.16Arg/Arg vs 4.28 mmol/L ± 2.79 in. p.16 Arg/Gly and p.16 Gly/Gly; P < 0.001, 95% CI of difference -2.40 ~ -0.82). In neonates born to mothers receiving ephedrine, the magnitude of the difference among genotypes was even greater (pH 7.30 ± 0.02 in p.16Arg/Arg vs. 7.19 ± 0.10 in p.16 Arg/Gly and p.16 Gly/Gly; P < 0.001, 95% CI of difference 0.07 ~ 0.14) and UA lactate was lower (3.66 mmol/L ± 1.30 in p.16Arg/Arg vs. 5.79 mmol/L ± 2.88 in p.16 Arg/Gly and p.16 Gly/Gly; P = 0.003, 95% CI of difference -3.48 ~ -0.80). In a multiple linear regression model (R² = 63.6%; P = 0.03), neonatal ADRB2 genotypes (p.16Arg/Arg and p.27Gln/Glu) and lower neonatal birth weight predicted lower UA lactate concentrations. Phenylephrine dose was not affected by maternal ADRB2 or NOS3 genotypes, and neonatal NOS3 genotype did not affect UA pH or UA lactate. In contrast to previous findings in a North American cohort, maternal ADRB2 genotype did not affect ephedrine requirements during elective cesarean delivery in a Chinese cohort. However, our findings suggest that neonatal ADRB2 p.Arg16 homozygosity confers a protective effect against developing ephedrine-induced fetal acidemia.