Bolus Doses Of Phenylephrine Research Articles

Comparative Efficacy of Intermittent Bolus Doses of Phenylephrine and Norepinephrine in Preventing Maternal Bradycardia during Cesarean Section under Spinal Anesthesia: A Randomized Controlled Trial

Background and Aims: Maternal hypotension is a common concern during cesarean sections (CS) with spinal anesthesia and can have adverse consequences for both the mother and fetus. This study aimed to investigate the prophylactic effectiveness of intermittent boluses of phenylephrine and norepinephrine in preventing maternal bradycardia during maintenance of systolic blood pressure (SBP) within 90–100% of baseline. Material and Methods: Two hundred American Society of Anesthesiologists physical status -II parturients scheduled for CS with subarachnoid block (SAB) were randomly assigned to Group A (phenylephrine, 50 µg) or Group B (norepinephrine, 4 µg). The primary goal was to assess the incidence of maternal bradycardia (≤50 bpm) whilst SBP maintenance at 90-100% of baseline. The secondary objectives encompassed total boluses administered, episodes of hypertension (≥120% of baseline), Intraoperative nausea and vomiting (IONV), and neonatal APGAR scores. The time from intrathecal injection to fetal delivery (induction–delivery interval) was also evaluated. Results: Both norepinephrine and phenylephrine groups effectively prevented spinal-induced hypotension, with similar outcomes However, Group A (phenylephrine) experienced a significantly higher incidence of bradycardia (18%) compared to Group B (norepinephrine) with only 5% (P=0.016). Episodes of hypertension, IONV, and neonatal APGAR scores were comparable between the two groups. Conclusion: Intermittent boluses of norepinephrine and phenylephrine demonstrated equivalent efficacy in preventing spinal-induced hypotension during CS. However, norepinephrine exhibited an advantage over phenylephrine by significantly reducing the incidence of bradycardia. These findings support the consideration of norepinephrine as an effective alternative vasopressor for maintaining maternal hemodynamics during CS under SAB.

Comparing the Effect of Phenylephrine Bolus and Phenylephrine Infusion for Maintaining Arterial Blood Pressure During Cesarean Delivery Under Spinal Anesthesia: A Randomized Prospective Study.

Maternal hypotension is a common complication of spinal anesthesia in cesarean section and requires immediate intervention. Phenylephrine is most commonly used as a vasopressor agent for the treatment of hypotension due to subarachnoid block.Our aim was to compare the bolus dose of 50 µg of phenylephrine with a fixed infusion at 50 µg.min-1 of phenylephrine for maintaining arterial blood pressure during cesarean delivery. This was a prospective, randomized comparative study. One hundred normotensive pregnant females aged 18-35 years, body mass index 18-29kg.m2, American Society of Anesthesiologists (ASA) physical status classificationIIscheduled to undergo cesarean section (elective/emergency) under spinal anesthesia were randomly divided into two groups of 50 each. Group PB received a bolus dose of phenylephrine 50 µg after they developed hypotension i.e., a decrease in systolic blood pressure (SBP) ≥ 20% from the baseline. Similarly, patients in Group PI were administered prophylactic infusion using a syringe pump of phenylephrine 50 µg.min-1, started just after the administration of subarachnoid block. The phenylephrine infusion was continued either till the delivery of the baby or when SBP rises >20% above the baseline. Parameters like blood pressure, heart rate, and peripheral oxygen saturation were recorded.After the delivery of the baby, theneonatal APGAR score was assessed at one minute and five minutes. Demographic data were comparable in terms of demographic profile, duration of surgery, and ASA physical status classificationbetween the groups. The heart rate was higher in Group PB compared to Group PI throughout the monitoring period (P<0.001). The fall in mean blood pressure was more in Group PB compared to Group PI till 18 minutes of surgery and was statistically significant (P<0.05). After 18 minutes of surgery, mean blood pressure stabilized and was comparable between the groups. Other variables like APGAR score at one minute and five minutes were comparable between the groups.Bradycardia and hypertension were more common in Group PI whereas hypotension, nausea, and vomiting were more common in group PB. We concluded that during cesarean section under spinal anesthesia, phenylephrine infusion provides better hemodynamic stability and APGAR score during the perioperative period.

Effectiveness of norepinephrine versus phenylephrine intravenous boluses for the treatment of hypotension in elective lower-segment cesarean section under spinal anesthesia: A randomized controlled, double-blind study

Abstract Background and Aim: Hypotension following spinal anesthesia is a common adverse effect during caesarean sections, with potentially harmful consequences for both the mother and the fetus. While phenylephrine is the current first-line treatment for maternal spinal hypotension during obstetric anesthesia, norepinephrine has been proposed as a possible alternative due to its weaker b-agonist-mediated positive chronotropic action. However, there is a lack of comparative data on the safety and efficacy of these two drugs in obstetric anesthesia. This study aimed to compare the number of bolus doses of phenylephrine and norepinephrine required to treat hypotension after spinal anesthesia in lower segment caesarean sections, as well as to evaluate maternal and fetal outcomes in both groups, including complications. Materials and Method: A prospective double-blinded randomized controlled trial was conducted, The study included 60 term parturients between the ages of 18 and 40, who had singleton pregnancy and were categorized as American Society of Anaesthesiologists (ASA) physical class II, and who were scheduled for elective caesarean section under spinal anesthesia. the parturients were randomized into two groups: Group N and Group P. Group P patients received an intravenous dose of phenylephrine 100 µg, while Group N patients received an intravenous dose of 8 µg whenever the systolic arterial pressure dropped below 20% of the baseline.primary objective was number of intravenous drugs required to treat spinal hypotension, secondary objective were incidence of maternal and foetal Complications. The data was collected on a form and entered into Excel. Statistical analysis was done using Epi Info 7.2.1.0 for Windows. The Kolmogorov-Smirnov test was used to check normality. Mean and standard deviation or median and range were used to present numerical data, while frequency and percentage were used for categorical data. T-tests compared quantitative variables, and Chi-square tests compared categorical data. Two-tailed tests were used, and a P-value of &lt;0.05 was considered significant. Result: The patient’s demographic profile was comparable in both groups.T he number of bolus doses of study drug required to treat spinal hypotension was significantly lower in Group N versus P (1.50 ± 0.57 vs. 2.13 ± 0.73, p =0.001)Incidence of bradycardia was more in group P, but not statistically significant. Other maternal complications like bradycardia, hypertension, nausea, vomiting, shivering were comparable in both groups. Conclusions: According to our study, Intermittent boluses of norepinephrine were effective in the management of spinal-induced hypotension during caesarean section. Norepinephrine boluses can thus be considered as an alternative to phenylephrine boluses.

To compare the efficacy of two different bolus doses of phenylephrine in combination with oxytocin in preventing oxytocin-induced hypotension during cesarean section under spinal anesthesia: A randomized comparative study

To compare the efficacy of two different bolus doses of phenylephrine in combination with oxytocin in preventing oxytocin-induced hypotension during cesarean section under spinal anesthesia: A randomized comparative study

Impact of hyperoxia and phenylephrine on cerebral oxygenation: An experimental clinical study.

Oxygen supply to the brain is of special importance during intracranial surgery because it may be compromised by intracranial pathology. A high arterial blood pressure (mean arterial pressure above 80 mmHg) and a high arterial oxygen tension (PaO2 above 12 kPa) is therefore often targeted in these patients, when for example intracranial pressure is increased or when a mass effect on brain tissue from a tumour is present, and it is pursued by administering vasopressors such as phenylephrine and by increasing inspiratory oxygen fraction (FiO2 ). However, whether these interventions increase cerebral oxygenation remains uncertain. We aimed to investigate the effect of hyperoxia and phenylephrine on brain tissue oxygen tension (PbtO2 ) in patients undergoing craniotomy. In this experimental study, we included 17 adult patients scheduled for elective craniotomy. After securing a stable baseline of the oxygen probe, PbtO2 was measured in white matter peripherally in the surgical field during general anaesthesia. Primary comparisons were PbtO2 before versus after an increase in FiO2 from 0.30 to 0.80 as well as before versus after a bolus dose of phenylephrine (0.1-0.2mg depending on patient haemodynamics). Data were analysed with the Wilcoxon signed rank test. We obtained complete data sets in 11 patients undergoing the FiO2 increase and six patients receiving the phenylephrine bolus. PbtO2 was 22 (median; 5%-95% range, 4.6-54) mmHg during 30% oxygen, 68 (8.4-99) mmHg during 80% oxygen (p=.004 compared to 30% oxygen), 21 (4.5-81) mmHg before phenylephrine, and 19 (4.2-56) mmHg after phenylephrine (p=.56 compared to before phenylephrine). In patients undergoing craniotomy under general anaesthesia, brain tissue oxygen tension increased with a high inspiratory oxygen fraction but remained unchanged after a bolus dose of phenylephrine.

Efficacy of Prophylactic Phenylephrine in Prevention of Hypotension in Parturient Undergoing Spinal Caesarean Section

To determine the hemodynamic (pulse, blood pressure) stability of prophylactic bolus dose of phenylephrine in caesarean section under spinal anaesthesia. Study design &amp; Setting: Interventional study was done from 13th Feb 2021 to 07th Oct 2021 at Islam Teaching Hospital, Sialkot. Methodology: Study approval was taken vide letter no.2021-05/AN dated 26-3-2021, issued by Chairman Ethical Review Board, Islam Medical College, Sialkot. Statistical software(version.3.1.9.2) with (prob of 0.80, critical 2 value 15.08), was employed and sample size calculated to be 200 cases i.e. groups-I (injection phenylephrine 100µgm) and group-II (placebo) divided by lottery method into 100 each given at spinal neuraxial block. Primary study variable being heart rate and blood pressure variations. Spearman’s Rank correlation statistical test was used to check interdependence between the two variables i.e., systolic blood pressure and pulse rate. SPSS version 21 was used. Results: In group-II, in 36% cases atropine was given as compared to 24% cases in group-I, thus 150 % more anti-cholinergic was used in group-II. In group-II, in 33% cases top-up of injection Adrenaline 10 microgram was used whereas given in 24% cases in group-I, thus 137.5 % more top-ups of vasopressors in group-II. In group-I, heart rate decreased by value of 9.02 % with respect to baseline value, while comparable reading noted was 3.42% decline in pulse rate in group-II respectively. Conclusion: Prophylactic phenylephrine at time of spinal injection resulted in stable blood pressure and pulse rate values in caesarean spinal delivery

Clinical Comparative Study of Effect of Two Different Doses of Phenylephrine on Spinal Induced Hypotension during Cesarean Section

Background and Aims: During Cesarean section, hypotension occurs in the most of parturients, following spinal anesthesia. This prospective observational study was undertaken to determine the efficacy of two different Bolus Doses of Phenylephrine for Prevention of Spinal-Induced Hypotension during Cesarean Section.&#x0D; Materials and Methods: A total of 120 parturients undergoing cesarean section were divided into two groups of group A and group B with sixty in each group. Group A received phenylephrine 75 mcg IV bolus, while Group B received phenylephrine 100 mcg IV bolus, immediately after giving spinal anesthesia. For the next 20 minutes, systolic blood pressure (SBP), diastolic blood pressure (DSP), mean arterial pressure (MAP), and heart rate (HR) were recorded every 2 minutes, and APGAR scores at 1 and 5 minutes were recorded.&#x0D; Results: There was no difference between the two groups in terms of preventing hypotension, with 16.6% in Group A and 16.6% in Group B. In the first 2–6 minutes, however, the rise in systolic pressure in Group B was higher than in Group A. Group B (46.66 %) had a higher rate of bradycardia than Group A (25 %).&#x0D; Conclusion: Both phenylephrine dosages were equally effective in preventing hypotension following spinal anesthesia. However, Prophylactic bolus dose of phenylephrine 75 mcg was found to be effective for the management of spinal-induced hypotension and should be preferred over 100 mcg which causes significant bradycardia and reactive hypertension.

Comparison of intravenous bolus doses of phenylephrine vs ephedrine along with crystalloid co-loading in the prevention of hypotension during spinal anesthesia for caesarean section

Caesarean section was the first obstetrical operation that saves the life of the baby when normal delivery fails. Spinal anaesthesia is the most appropriate method for caesarean section. But hypotension is the most common side effect of it in patient with pregnant uterus. To compare the vasopressor effects of ephedrine and phenylephrine in ameliorating hypotension in elective caesarean delivery receiving crystalloid coloading, during intrathecal bupivacaine injection.: Study participants were randomly divided into two groups of 50 patients each. After subarachnoid block, all the parturients were given rapid administration of ringer lactate solution 20ml/kg, during the initial 5 minutes of surgery the parameters such as oxygen saturation, blood pressure and pulse rate recorded for every one minute followed by every five minutes until the completion of the surgery. The incidence of hypotension, bradycardia, nausea/vomiting, block height and requirements of vasopressor (ephedrine and phenylephrine) were recorded. Apgar score, and blood sample from umbilical cord was taken and sent for blood gas analyses to determine the neonatal outcome.: Vasopressor consumption was more in phenylephrine group (92±112 µg) compared to ephedrine group (4.8±5.5 mg) which was statistically significant p=0.0001. The neonatal outcome was statistically significant regarding umbilical cord pH (Group E-7.2±0.06 and Group P-7.37±0.04 with p=0.002) but clinically no true fetal acidosis in either groups and no significant changes regarding Apgar score in the two groups.: Thus we conclude that that ephedrine 6 mg and phenylephrine 100 µg does not differ in their efficacy to manage hypotension during spinal anaesthesia for caesarean delivery. However, maternal bradycardia was more in the phenylephrine group with equal incidence of fetal acidosis in the study groups.

A randomised double-blind comparison of phenylephrine and norepinephrine for the management of postspinal hypotension in pre-eclamptic patients undergoing caesarean section.

Studies comparing phenylephrine and norepinephrine for the treatment of postspinal hypotension in pre-eclamptic patients are limited. To compare bolus doses of phenylephrine and norepinephrine for treating hypotension in pre-eclamptic mothers undergoing caesarean section under spinal anaesthesia. It was hypothesised that norepinephrine and phenylephrine use would be associated with similar neonatal outcome. Randomised controlled study. Single centre, tertiary care, university teaching hospital, from December 2018 to March 2020. A total of 86 women with pre-eclampsia and a singleton pregnancy who developed postspinal hypotension during caesarean section. Patients received intravenous phenylephrine (50 μg) or norepinephrine (4 μg) for treatment of hypotension, defined as a fall in baseline systolic BP by ≥ 20% or an absolute value < 100 mmHg. The primary outcome was umbilical artery pH. Secondary outcomes included Apgar scores, the number of hypotensive episodes, vasopressor requirements, the incidence of tachycardia/bradycardia/arrhythmias/hypertension and maternal complications. Umbilical artery pH was not different between the phenylephrine and norepinephrine groups (7.26 ± 0.06 and 7.27 ± 0.06, respectively; P = 0.903). The median [IQR] number of hypotensive episodes was higher in the norepinephrine than the phenylephrine group: 2 [1 to 3] vs 1 [1 to 2], respectively; P = 0.014. Apgar scores, total number of vasopressor boluses required, systolic BP trends and the incidence of maternal complications were comparable in the two groups. Heart rate (HR) values were lower in phenylephrine group (P = 0.026), and one patient in phenylephrine group and none in the norepinephrine group developed bradycardia (HR < 50 bpm), P = 1.000. In women with pre-eclampsia undergoing caesarean section, bolus doses of phenylephrine (50 μg) and norepinephrine (4 μg) used to treat hypotension after spinal anaesthesia are equally effective with similar neonatal and maternal outcomes. CTRI/2018/11/016478.

Comparison of bolus phenylephrine, Ephedrine and Mephentermine for maintenance of arterial pressure during Spinal anaesthesia in Caesarean section

Background: Hemodynamic changes during cesarean delivery after spinal anesthesia are common. The hypotension seen after spinal anesthesia in a cesarean delivery can be treated by many agents. In the management of hypotension during spinal anesthesia for cesarean section, the effects of Phenylephrine, Ephedrine and Mephentermine were compared in this study based on the following parameters-1. The efficacy of the vasopressor in treating hypotension 2. Incidence of undesirable side effects. Materials and method: This study included a total of 120 patients (ASA Grade I and II) undergoing elective cesarean section (with a normal singleton pregnancy, full term/near term) under spinal anesthesia. The patients were randomly allocated into three groups of 40 each. Group ‘P’ was given prophylactic bolus dose of Phenylephrine 100 mcg IV, Group ‘E’ was given prophylactic bolus dose of Ephedrine 10 mg IV and Group ‘M’ received prophylactic bolus dose of Mephentermine 6 mg IV. Blood pressure and heart rate was recorded every 2 minutes for 20 minutes and thereafter every 5 minutes till the end of the surgery. Results: In managing hypotension between the three groups, no difference was found between them. The incidence of bradycardia was higher in the Phenylephrine group. Conclusion: All the three vasopressors are effective (in intravenous form) in maintenance of maternal arterial pressure. Although Phenylephrine has quicker peak effect, in comparison to Ephedrine and Mephentermine and it causes reduction in heart rate.

Testing individual baroreflex responses to hypoxia-induced peripheral chemoreflex stimulation

IntroductionBaroreflexes and peripheral chemoreflexes control efferent autonomic activity making these reflexes treatment targets for arterial hypertension. The literature on their interaction is controversial, with suggestions that their individual and collective influence on blood pressure and heart rate regulation is variable. Therefore, we applied a study design that allows the elucidation of individual baroreflex–chemoreflex interactions.MethodsWe studied nine healthy young men who breathed either normal air (normoxia) or an air–nitrogen–carbon dioxide mixture with decreased oxygen content (hypoxia) for 90 min, with randomization to condition, followed by a 30-min recovery period and then exposure to the other condition for 90 min. Multiple intravenous phenylephrine bolus doses were applied per condition to determine phenylephrine pressor sensitivity as an estimate of baroreflex blood pressure buffering and cardiovagal baroreflex sensitivity (BRS).ResultsHypoxia reduced arterial oxygen saturation from 98.1 ± 0.4 to 81.0 ± 0.4% (p < 0.001), raised heart rate from 62.9 ± 2.1 to 76.0 ± 3.6 bpm (p < 0.001), but did not change systolic blood pressure (p = 0.182). Of the nine subjects, six had significantly lower BRS in hypoxia (p < 0.05), two showed a significantly decreased pressor response, and three showed a significantly increased pressor response to phenylephrine in hypoxia, likely through reduced baroreflex buffering (p < 0.05). On average, hypoxia decreased BRS by 6.4 ± 0.9 ms/mmHg (19.9 ± 2.0 vs. 14.12 ± 1.6 ms/mmHg; p < 0.001) but did not change the phenylephrine pressor response (p = 0.878).ConclusionWe applied an approach to assess individual baroreflex–chemoreflex interactions in human subjects. A subgroup exhibited significant impairments in baroreflex blood pressure buffering and BRS with peripheral chemoreflex activation. The methodology may have utility in elucidating individual pathophysiology and in targeting treatments modulating baroreflex or chemoreflex function.

Novel Approach to Elucidate Human Baroreflex Regulation at the Brainstem Level: Pharmacological Testing During fMRI.

Introduction: Brainstem nuclei govern the arterial baroreflex, which is crucial for heart rate and blood pressure control. Yet, brainstem function is difficult to explore in living humans and is therefore mostly studied using animal models or postmortem human anatomy studies. We developed a methodology to identify brainstem nuclei involved in baroreflex cardiovascular control in humans by combining pharmacological baroreflex testing with functional magnetic resonance imaging.Materials and Methods: In 11 healthy men, we applied eight repeated intravenous phenylephrine bolus doses of 25 and 75 μg followed by a saline flush using a remote-controlled injector during multiband functional magnetic resonance imaging (fMRI) acquisition of the whole brain including the brainstem. Continuous finger arterial blood pressure, respiration, and electrocardiogram (ECG) were monitored. fMRI data were preprocessed with a brainstem-specific pipeline and analyzed with a general linear model (GLM) to identify brainstem nuclei involved in central integration of the baroreceptor input.Results: Phenylephrine elicited a pressor response followed by a baroreflex-mediated lengthening of the RR interval (25 μg: 197 ± 15 ms; 75 μg: 221 ± 33 ms). By combining fMRI responses during both phenylephrine doses, we identified significant signal changes in the nucleus tractus solitarii (t = 5.97), caudal ventrolateral medulla (t = 4.59), rostral ventrolateral medulla (t = 7.11), nucleus ambiguus (t = 5.6), nucleus raphe obscurus (t = 6.45), and several other brainstem nuclei [p < 0.0005 family-wise error (few)-corr.].Conclusion: Pharmacological baroreflex testing during fMRI allows characterizing central baroreflex regulation at the level of the brainstem in humans. Baroreflex-mediated activation and deactivation patterns are consistent with previous investigations in animal models. The methodology has the potential to elucidate human physiology and mechanisms of autonomic cardiovascular disease.

Prophylactic administration of two different bolus doses of phenylephrine for prevention of spinal-induced hypotension during cesarean section: A prospective double-blinded clinical study

Background: Hypotension following spinal anesthesia during cesarean delivery can cause adverse maternal and fetal effects. Phenylephrine has been found to be a potent vasopressor in preventing spinal-induced hypotension during cesarean section (CS) without fetal acidosis. Material and Methods: In this prospective double-blinded study, 120 parturients of ASA grade I and II posted for CS under spinal anesthesia were randomized into three groups of 40 each: group P0, group P75, and group P100. The primary objective was to study the influence of two different doses of phenylephrine on the incidence of spinal-induced hypotension during cesarean section. Corelation of postural variations in baseline hemodynamic data with observed degree of orthostatic hypotension to predict intraoperative hypotension, requirement of rescue vasopressors, and incidence of side effects and neonatal outcome were the secondary outcome measures. Statistical analysis was done with SPSS version 16 using student t test, ANOVA, and Chi-square test. Results: Incidence of hypotension was 70%, 25%, and 17.50% in P0, P75, and P100 groups (P

Abstract 17166: Comparison Between Use of Vasoactive Medications in Patients Undergoing PVC and VT Ablation

Background: Societal guidelines have set prerequisites regarding procedures conducted in the EP lab. Despite metrics for management of EP cases, no clear guidelines exist for use of hemodynamic drugs to support complex ablations, particularly in setting of structural heart disease. Objectives: We sought to understand the variety and range of vasoactive medication use in patients undergoing PVC/VT ablation. Methods: Patients undergoing PVC or VT ablation, from January 2015 to December 2016, at our institution were analyzed. Demographics, echocardiography, and procedural details, including vasoactive medication use, were analyzed. Results: Sequential patients undergoing PVC or VT ablation (70 in each arm) were studied. Those undergoing PVC ablation (56 +/- 14 years, 30% female) had an average EF of 58% in comparison to 44% (p&lt;0.01 for EF difference) in VT ablation patients (60 +/- 13 years, 20% female); more VT patients (62%) were under general anesthesia. Pressors were administered in 86% of cases with the significant majority (63%) consisting of alpha-agonists (phenylephrine, ephedrine, epinephrine). Importantly, 48% of cases required continuous drip initiation (Figure). Regardless of case type or abnormal EF, drip initiation with or administration of multiple bolus doses of alpha-agonists was much more frequent compared to inotropes (Figure). In a subset of patients with EF ≤ 35%, 96% received vasoactive medications with 73% receiving a continuous drip or multiple bolus doses of phenylephrine. Conclusions: Vasoactive medication use during ventricular EP cases is common. Regardless of baseline EF, a propensity for use of alpha-agonists exists that may affect the treatment of patients with abnormal LV function. More studies are needed to assess the impact of pressor use on patient safety and procedural endpoints in the EP lab. Figure:

A Comparative Study of Two Different Intravenous Bolus Doses of Phenylephrine Used Prophylactically for Preventing Hypotension after Subarachnoid Block in Cesarean Sections.

Background and Aims:Hypotension occurs in most of the cases following subarachnoid block in for cesarean sections. Studies comparing different bolus doses of phenylephrine for preventing hypotension induced by subarachnoid block in cesarean sections are sparse.Settings and Design:This study was conducted to compare the efficacy of two different bolus doses of phenylephrine for preventing subarachnoid block-induced hypotension in cesarean sections.Materials and Methods:Sixty parturients undergoing cesarean section were allocated into two groups. Group A (n = 30) received 150 mcg phenylephrine intravenously (IV) and Group B (n = 30) received 200 mcg phenylephrine IV prophylactically immediately after subarachnoid block. Then, for every 2 min, systolic blood pressure, diastolic blood pressure, mean arterial pressure (MAP), and heart rate (HR) were measured for 20 min, and APGAR scores were measured.Statistical Analysis:The observations are expressed as mean ± standard deviation and were compared using unpaired t-test. The statistical significance of difference between groups was based on P value. P < 0.05 was considered statistically significant.Results:There was no difference in preventing hypotension in both the groups, the incidence in Group A being 16.6% and Group B also 16.6%. However, the rise in systolic pressure in Group B was higher than Group A in the first 2–6 min. The incidence of bradycardia was higher in Group B (43.3%) than Group A (20%).Conclusions:Both the doses of phenylephrine were equally efficient in prevention of hypotension after subarachnoid block. Lower prophylactic bolus phenylephrine 150 mcg IV is better in the prevention of hypotension after subarachnoid block in cesarean sections as the incidence of bradycardia is higher with phenylephrine 200 mcg.

Norepinephrine Intermittent Intravenous Boluses to Prevent Hypotension During Spinal Anesthesia for Cesarean Delivery: A Sequential Allocation Dose-Finding Study.

The use of phenylephrine as the first-line agent for prevention and treatment of maternal hypotension during cesarean delivery (CD) may reduce cardiac output, posing a theoretical risk to mother and fetus. Norepinephrine has been suggested as a potential alternative, because its β-adrenergic effects might result in greater heart rate and cardiac output than phenylephrine. The use of norepinephrine to prevent and treat hypotension during CD is new, and its use as a bolus has not been fully determined in this context. The purpose of this study was to determine the effective norepinephrine dose, when given as intermittent intravenous (IV) boluses, to prevent postspinal hypotension in 90% of women undergoing elective CD (ED90). This was a prospective, double-blind sequential allocation dose-finding study, using the biased coin up-and-down design. Forty-term pregnant women undergoing elective CD under spinal anesthesia received a set intermittent norepinephrine bolus of either 3, 4, 5, 6, 7, or 8 µg every time their systolic blood pressure (SBP) fell to below 100% of baseline. The primary outcome was the success of the norepinephrine regimen to maintain SBP at or above 80% of baseline, from induction of spinal anesthesia to delivery of the fetus. Secondary outcomes included nausea, vomiting, hypertension (SBP > 120% of baseline), bradycardia (<50 bpm), upper sensory level of anesthesia to ice cold and umbilical artery and vein blood gases. The ED90 and 95% confidence intervals (CIs) were estimated using both truncated Dixon and Mood and isotonic regression methods. The estimated ED90 of norepinephrine was 5.49 µg (95% CI, 5.15-5.83) using the truncated Dixon and Mood method and 5.80 µg (95% CI, 5.01-6.59) using the isotonic regression method. The use of intermittent IV norepinephrine boluses to prevent spinal-induced hypotension in elective CD seems feasible and was not observed to be associated with adverse outcomes. Practically, we suggest an ED90 dose of 6 µg. Further work is warranted to elucidate the comparative effects of intermittent IV bolus doses of phenylephrine and norepinephrine, in terms of efficacy and safety.

Ephedrine versus Phenylephrine: Prevention of Hypotension during Spinal Anaesthesia for Cesarean Section and Effects on the Fetus

Background: Hypotension during spinal anaesthesia for cesarean section is secondary to the sympathetic blockade and aorto-caval compression by the uterus and it can be deleterious to both the fetus and the mother. Ephedrine and phenylephrine improve venous return after sympathetic blockade during the spinal anaesthesia. Aim: The aim of this study was to compare intravenous bolus doses of phenylephrine and ephedrine in preventing and treating hypotension in spinal anaesthesia for caesarean section and the effect of vasopressors on fetal outcome in terms of Apgar score. Materials and Methods: Total 100 patients of ASA Grade I undergoing caesarean section under spinal anaesthesia with a normal singleton pregnancy beyond 37 weeks gestation was randomly allocated into two groups of 50 each. Group I received prophylactic bolus dose of ephedrine 10 mg IV at the time of intrathecal block with rescue boluses of 5 mg. Group II received prophylactic bolus dose of phenylephrine 100 ¼g IV at the time of intrathecal block with rescue boluses of 50 ¼g. Hemodynamic variables like blood pressure and heart rate was recorded every 2 minutes up to delivery of baby and then after every 5 minutes. Neonatal outcome was assessed using Apgar score at 1 and 5 minutes and neonatal umbilical cord blood pH Values. Results: There was no difference found in managing hypotension between two groups. Incidence of bradycardia was higher in phenylephrine group. The differences in umbilical cord pH, Apgar score, and birth weight between two groups were found statistically insignificant. Conclusion: Ephedrine and Phenylephrine are equally efficient in managing hypotension during spinal anesthesia for caesarean section. There was no difference between two vasopressors in the incidence of true fetal acidosis. Neonatal outcome remains equally good in both the groups. JBSA 2017; 30(1): 41-47

The Effects of Prophylactic Bolus Phenylephrine on Hypotension During Low-dose Spinal Anesthesia for Cesarean Section

(Int J Obstet Anesth. 2016;25:17–22) Spinal anesthesia for cesarean section is preferred in order to avoid the serious maternal complications that can occur during general anesthesia. However, spinal anesthesia is not without complications. Spinal anesthesia-induced hypotension occurs commonly and may have deleterious effects on both mother and fetus. To decrease the risk of hypotension a continuous infusion of phenylephrine is frequently administered, but there are limited data about the use of prophylactic boluses of the drug. The objective of this study was to evaluate the effects of 3 prophylactic bolus doses of phenylephrine during low-dose spinal anesthesia for cesarean section, including adverse hemodynamic effects and neonatal outcome.

The impact of push-dose phenylephrine use on subsequent preload expansion in the ED setting

BackgroundThe utilization of bolus-dose phenylephrine (PHE) has transitioned to the emergency department (ED) for the treatment of acutely hypotensive patients, despite a paucity of literature in this setting. MethodsThis was a single center retrospective chart review of the utilization of bolus-dosed PHE for acute hypotension in the ED at an academic non-forprofit hospital. The primary objective of this study is to report the frequency of patients that were initiated on a continuous vasopressor infusion (CVI) within 30 minutes after the first administration of bolus-dose PHE. Secondary objectives included an observational description of the impact of early preload expansion (fluids) on the initiation of CVIs in the setting of bolus-dose PHE in the ED. ResultsSeventy-three patients met inclusion criteria for analysis. The primary outcome, 46.5% (n = 34) of patients were initiated on a CVI within 30 minutes following bolus-dose PHE. Initial preload expansion (30 mL/kg of IV fluids) was found to be significantly disproportionate with 34.2% appropriately fluid challenged vs 65.8% (P = .0048). In addition, a significant decrease in the number of PHE bolus doses were required [1.5 vs 2.3 (P = .01)] in the adequately IVF challenged group.For secondary endpoints, PHE was most commonly indicated for peri-intubation hypotension (n = 52, 71.2%). Significant adverse events were documented for 15 (20.5%) patients, with bradycardia (n = 7; 9.6%) as the most common adverse event. ConclusionsInitial preload IVF expansion was found to be significantly disproportionate, and appears to be associated with an increase number of phenylephrine bolus doses in our study population.

English

Introduction: Presently the mainstay in management of hypotension is the use of Vasopressor agents, but those currently available are not ideal and there has been an ongoing search for ideal vasopressor. Ephedrine is supposed to be most widely used agent for this purpose, but causes maternal tachycardia due to its non selective action on both alpha and beta adrenergic receptors. It is difficult to titrate and also exhibits the phenomena of tachyphylaxis due to its indirectly acting nature. Hence there is a need to find an alternative drug for the treatment of hypotension, which lacks the forementioned maternal side effects and also does not cause any detrimental effect on the fetus. Objective of the study was to compare the efficacy of intravenous bolus dose of Phenylephrine (40 mcg) with Ephedrine (6mg) to maintain arterial blood pressure during spinal anaesthesia for Caesarean section.