Phenylephrine Bolus Research Articles

Comparison of Phenylephrine Bolus and Infusion Regimens on Maternal and Fetal Outcomes During Cesarean Delivery: A Systematic Review and Meta-Analysis

BACKGROUND: A systematic review and meta-analysis was conducted to compare phenylephrine boluses versus prophylactic infusion in parturients undergoing cesarean delivery under spinal or combined spinal-epidural anesthesia on feto-maternal outcomes. METHODS: Medline, Embase, Cochrane, and US Clinical registry databases were searched. Studies comparing phenylephrine boluses (both therapeutic and prophylactic) with infusion (both fixed- and variable-rate) assessing various feto-maternal outcomes were included. The primary outcome was the incidence of maternal hypotension. Secondary maternal outcomes included the incidence of reactive hypertension, bradycardia, nausea, or vomiting; secondary neonatal outcomes included umbilical arterial pH, partial pressure of oxygen (paO2), umbilical venous pH, fetal acidosis, Apgar Scores at 1 and 5 minutes. All outcomes were quantitatively analyzed using the random effects model. Risk of bias was assessed using the Cochrane Collaboration R0B 2.0 tool. RESULTS: We included 15 studies with 2153 parturients. The parturients receiving phenylephrine bolus during cesarean delivery under spinal or combined spinal-epidural anesthesia had a significant increase in the incidence of predelivery hypotension compared to phenylephrine infusion (risk ratio [RR], 2.34, 95% confidence interval [CI], 1.72–3.18). Reactive hypertension (RR, 0.48, 95% CI, 0.29–0.79) and bradycardia (RR, 0.57, 95% CI, 0.41–0.79) were less common in the parturients receiving phenylephrine bolus; whereas, vomiting (RR, 2.15, 95% CI, 1.53–3.03) was more common compared to the infusion group. No statistically significant difference was observed in the incidence of nausea or any fetal outcomes (umbilical artery pH, paO2, umbilical venous pH, fetal acidosis, and Apgar scores at 1 and 5 minutes) between either of the groups. Three studies had a high risk of bias. CONCLUSIONS: A prophylactic phenylephrine infusion significantly reduces the incidence of predelivery hypotension in parturients undergoing cesarean delivery under neuraxial anesthesia in comparison to the therapeutic or prophylactic phenylephrine bolus group. A prophylactic phenylephrine infusion may be considered in all parturients without preexisting hypertensive disorder or cardiovascular disorders to reduce the risk of predelivery hypotension. More evidence is needed to guide optimal hemodynamic management for patients with hypertensive or cardiovascular disorders.

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

In vivo optical assessment of cerebral and skeletal muscle microvascular response to phenylephrine.

This study aimed to investigate the simultaneous response of the cerebral and skeletal muscle microvasculature to the same phenylephrine (PE) boluses. A hybrid optical system that combines hyperspectral near-infrared spectroscopy (hs-NIRS) and diffuse correlation spectroscopy (DCS) was used to monitor changes in tissue oxygenation and perfusion. Data were collected from the head and hind limb of seven male Sprague-Dawley rats while administering intravenous (IV) injections of PE or saline to all animals. The response to saline was used as a control. Skeletal muscle oxygenation decreased significantly after PE injection, while a statistically underpowered decrease in perfusion was observed, followed by an increase beyond baseline. Vascular conductance also decreased in the muscle reflecting the drug's vasoconstrictive effects. Tissue oxygenation and perfusion increased in the brain in response to PE. Initially, there was a sharp increase in cerebral perfusion but no changes in cerebral vascular conductance. Subsequently, cerebral flow and vascular conductance decreased significantly below baseline, likely reflecting autoregulatory mechanisms to manage the excess flow. Further, fitting an exponential function to the secondary decrease in cerebral perfusion and increase in muscular blood flow revealed a quicker kinetic response in the brain to adjust blood flow. In the skeletal muscle, PE caused a transient decrease in blood volume due to vasoconstriction, which resulted in an overall decrease in hemoglobin content and tissue oxygen saturation. Since PE does not directly affect cerebral vessels, this peripheral vasoconstriction shunted blood into the brain, resulting in an initial increase in oxygenated hemoglobin and oxygen saturation.

Calculation of Effective Dose of Phenylephrine Bolus for Treatment of Post–Spinal Hypotension in Preeclamptic Patients Undergoing Caesarean Section—A Nonrandomized Controlled Trial

Calculation of Effective Dose of Phenylephrine Bolus for Treatment of Post–Spinal Hypotension in Preeclamptic Patients Undergoing Caesarean Section—A Nonrandomized Controlled Trial

Prophylactic phenylephrine infusion versus treatment with vasopressor bolus as needed during non-urgent cesarean delivery and neonatal acidemia: a retrospective cohort study (2016–2021)

IntroductionProphylactic vasopressor administration reduces spinal hypotension during cesarean delivery, however the effects of vasopressor administration on neonatal acidemia remain uncertain. We examined the occurrence of neonatal acidemia in the setting of non-urgent cesarean delivery and compared outcomes between cases receiving prophylactic phenylephrine infusion versus cases treated with boluses of phenylephrine. MethodsRetrospective cohort study with ethical approval, comparing non-urgent cesarean delivery cases performed under spinal anesthesia (2016 to 2021), receiving either prophylactic phenylephrine infusion or boluses as needed.Data were collected from anesthesia and labor ward electronic medical records. Records with missing pH or missing blood pressure data were excluded. The independent variable was prophylactic phenylephrine administration, a strategy implemented following international recommendations in 2018. The main outcome was neonatal acidemia, defined as umbilical artery pH < 7.1. The secondary outcome was maternal hypotension, defined as at least one systolic blood pressure (SBP) measurement below 100 mmHg or below 80% baseline. ResultsA total of 4392 patients were included in the final analysis; 1318 (30.0%) received prophylactic phenylephrine infusion. Neonatal acidemia (umbilical artery pH < 7.1) occurred in 28 (2.1%) cases receiving prophylactic phenylephrine versus 50 (1.6%) treated with boluses as needed (p = 0.188). Prophylactic phenylephrine infusion was not associated with occurrence of neonatal acidemia (aOR 0.83; 95% CI 0.52 to 1.33, p = 0.435). Prophylactic phenylephrine infusion was associated with a reduced spinal hypotension rate when defined as SBP < 100 mmHg (OR 0.47; 95% CI 0.37 to 0.57; p < 0.001), with similar results when hypotension was defined as a drop below 80% or 90% of baseline SBP. ConclusionIn this pragmatic study, prophylactic phenylephrine infusion was associated with a reduction in maternal spinal hypotension, but not reduced neonatal acidemia.

Comparison of intravenous bolus phenylephrine, ephedrine and mephentermine for maintenance of arterial blood pressure during spinal anaesthesia in caesarean section

Background: Subarachnoid block, although being highly efficient, often has limitation such as hypotension which can result in adverse maternal and fetal outcome, continues to be a matter of concern to the Anesthesiologist. The study was to compare the effect of phenylephrine, ephedrine and mephentermine, for maintenance of arterial pressure during spinal anaesthesia for caesarean section. Methodology: A prospective randomized double blinded study involving 90 patients with hypotension after subarachnoid block under spinal anesthesia was conducted, dividing them into three groups: P (Phenylephrine) 100 mcg, E (Ephedrine) 6 mg, and M (Mephentermine) 6 mg. Patients were compared based on age, weight, height, hemodynamic parameters, complications, and neonatal APGAR scores. Results: On inter-group comparison rise in systolic, diastolic and mean arterial blood pressure at 1,2,4 and 6min after drug administration were significantly high in phenylephrine group (p &lt;0.01) compared to ephedrine and mephentermine group. Thereafter the differences narrowed off. Heart rate was raised during episodes of hypotension. The mean heart rate was decreased significantly (p&lt;0.05) in phenylephrine group compared to other two groups. The neonatal APGAR score were &gt;/= 7 in the three groups at the 1st and 5th min. Conclusion: The study found that phenylephrine, ephedrine, and mephentermine effectively maintained arterial blood pressure in intravenous bolus form during subarachnoid block for caesarean section. Phenylephrine, a fast-acting, short-lived normotensive drug, significantly reduced heart rate compared to ephedrine and mephentermine, but did not cause significant adverse effects on mother and fetus. Keywords: hypotension; ephedrine; mephentermine; phenylephrine; subarachnoid block

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.

Comparison of Prophylactic Phenylephrine Infusion and Rescue Bolus Administration for Maintaining Blood Pressure During Spinal Anaesthesia for Caesarean Delivery in Obese Parturient: A Randomised Control Trial.

Phenylephrine (PE) is one of the vasopressor used to treat hypotension during anaesthesia. The primary aim of this study was to compare the effect of prophylactic infusion and rescue bolus of PE on the haemodynamic changes during spinal anaesthesia (SA) for Caesarean section (CS) in obese parturients. A total of 74 obese parturients scheduled for elective CS under SA were randomised into two groups; Group A (n = 37) received prophylactic PE infusion starting at 50 μg min-1 and adjusted according to the given algorithm and Group B (n = 37) received 100 μg PE bolus to treat hypotension. The measured parameters were systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), the total requirement of PE and neonatal Apgar score. Six patients were excluded from the analysis due to missing data and only 68 were analysed. Group A showed significantly higher SBP, DBP and MAP than Group B (P < 0.05). The requirement of PE was higher in Group A than Group B [817.7 (265.7) μg versus 360.6 (156.0) μg; P = < 0.05]. Both groups had no difference in terms of the neonatal Apgar score. Prophylactic PE infusion provided better haemodynamic control than therapeutic boluses in obese parturients undergoing CS under SA.

To Compare the Effects of IV Bolus Doses Phenylephrine, And Ephedrine Injection in Maintaining Arterial Blood Pressure During Spinal Anesthesia for Cesarean Sections-A Randomized Comparative Study

Spinal anesthesia is the preferred anesthetic approach for cesarean sections due to its benefits for both the mother and fetus. However, hypotension is a common and potentially harmful complication. Phenylephrine (PE) is frequently used as a vasopressor to manage hypotension during spinal anesthesia, but it can cause maternal sinus bradycardia. This study aimed to compare two strategies for maintaining arterial blood pressure during cesarean delivery: a 20 mcg bolus of phenylephrine followed by a 10 mcg/min infusion (Group P) versus a 6 mg bolus of ephedrine followed by a 0.1 mg/min infusion (Group E). A total of 100 pregnant women scheduled for elective or emergency cesarean sections under spinal anesthesia were randomly assigned to either Group P or Group E. Systolic blood pressure was well-maintained in both groups during the first 20 minutes. After this period, Group P’s blood pressure stabilized towards basal values, while Group E's remained slightly above basal levels—a statistically significant difference (p &lt; 0.005). Diastolic blood pressure fell in both groups, but Group E maintained slightly higher levels than Group P. Group P had a 24% incidence of bradycardia requiring atropine, while no such cases were observed in Group E. Despite these differences, overall maternal arterial blood pressure was effectively maintained in both groups, with no significant difference in uterine tone or bleeding levels.

Effect of pneumatic leg compression on phenylephrine dose for hypotension prophylaxis via variable rate infusion at cesarean delivery: an unblinded randomized controlled trial

BackgroundPhenylephrine infusion is recommended to prevent spinal hypotension during cesarean delivery (CD) but may be associated with dose-dependent side effects. We hypothesized that adding intermittent pneumatic compression (IPC) of the lower legs to a variable-rate phenylephrine infusion will reduce the dose of phenylephrine required during CD. MethodsSeventy-six healthy women undergoing elective CD under combined spinal-epidural anesthesia were randomly assigned to IPC or control groups (n = 38 per group). After spinal anesthesia, IPC of the lower legs was initiated in the IPC group, and all women received a phenylephrine infusion starting at 25 μg·min−1 and increasing by 16.7 μg·min−1 for systolic blood pressure (SAP) < 90% baseline. If hypotension (SAP < 80% baseline) occurred, 100 μg phenylephrine bolus was administered. The primary outcome was the dose of phenylephrine per minute. ResultsThe dose of phenylephrine per minute (34.4 ± 7.3 μg·min−1 vs. 40.9 ± 9.5 μg·min−1, P = 0.001; mean difference −6.6 μg·min−1, 95% CI −10.5 to −2.7 μg·min−1) and the incidence of hypotension (24% vs. 55%, P = 0.005) were lower in the IPC group than in the control group. There were no significant differences between the two groups in the total dose of phenylephrine (603.2 ± 217.1 μg vs. 706.2 ± 247.5 μg, P = 0.058; mean difference −102.9 μg, 95% CI −209.4 to 3.5 μg), maternal side effects, or neonatal outcomes. ConclusionsIntermittent pneumatic compression combined with a variable-rate phenylephrine infusion reduced the phenylephrine dose per minute and the incidence of hypotension during CD under spinal anesthesia.

Comparison of intermittent boluses of noradrenaline vs. phenylephrine for spinal anesthesia induced hypotension during cesarean delivery

Background and Objective: Maternal hypotension is a common consequence of spinal anesthesia for cesarean delivery (CD). A vasopressor is recommended in addition to adequate fluid loading to raise mean arterial pressure in pregnant women. Phenylephrine, a pure α–adrenergic receptor agonist, is the first-line agent to manage it. However, phenylephrine is associated with dose-dependent reflex bradycardia and decreased cardiac output. Noradrenaline is suggested as an alternative due to its mild beta-adrenergic effect, which results in a greater heart rate and cardiac output than phenylephrine. We compared the effectiveness and adverse effects of intermittent boluses of noradrenaline with phenylephrine to treat spinal-induced hypotension during CD.&#x0D; Methodology: A randomized controlled trial was conducted at Bach Mai Hospital, Vietnam, from May 2020 to August 2020. There were 120 pregnant women undergoing elective CD under spinal anesthesia enrolled in the study and divided randomly into two groups: the Group N and the Group P. Group N patients were given noradrenaline 6 µg as an intravenous bolus, and Group P patients were given phenylephrine 100 µg to treat spinal-induced hypotension. The primary outcome was the number of bolus doses of vasopressors needed to treat maternal hypotension. Secondary outcomes were bradycardia, hypertension, nausea, vomiting, umbilical arterial blood gases, and APGAR scores.&#x0D; Results: The number of boluses of vasopressors needed to treat hypotension and maternal hemodynamic changes was equivalent in both groups. The incidence of bradycardia, nausea, and vomiting in the two groups was not significantly different. No pregnant woman suffered from unintended hypertension. APGAR scores were 7 and above at one min and 10 and above at five min for all cases. There were no differences in umbilical arterial pH values between the two groups (7.33 vs. 7.34; P &gt; 0.05).&#x0D; Conclusion: Noradrenaline 6 µg and phenylephrine 100 µg boluses were equally effective in treating spinal-induced hypotension in parturients undergoing cesarean delivery with similar neonatal and maternal outcomes.&#x0D; Abbreviations: CD - Cesarean Delivery; HR - Heart Rate; CO - Cardiac Output; SVR - Systemic Vascular Resistance; SBP - Systolic Blood Pressure; ED 90 - 90 Percent Effective Dose&#x0D; Key words: Anesthesia, Spinal; Hypotension; Cesarean Delivery&#x0D; Citation: Nguyen TT, Nguyen HC, Nguyen ATH, Doan TH, Ngo QS. Comparison of intermittent boluses of noradrenaline vs. phenylephrine for spinal anesthesia induced hypotension during cesarean delivery. Anaesth. pain intensive care 2023;27(5):562−566.&#x0D; DOI: 10.35975/apic.v27i5.2312&#x0D; Received: August 22, 2023; Reviewed: August 23, 2023; Accepted: August 31, 2023

Calculation of effective dose of phenylephrine bolus for treatment of post-spinal hypotension in pre-eclamptic patients undergoing caesarean section – a non-randomised controlled trial

BackgroundPatients with pre-eclampsia require smaller vasopressor doses compared with those with normotension for management of post-spinal hypotension during caesarean section. However, the literature has little evidence as to the phenylephrine dose required for patients with pre-eclampsia. MethodsFifty patients, with either pre-eclampsia or normotension, and developing post-spinal hypotension during caesarean section under spinal anaesthesia, were studied. Women in both groups did not receive prophylactic vasopressors. The first patient in each group received phenylephrine 50 µg to treat the first episode of hypotension, defined as fall of systolic blood pressure ≥20% from baseline or an absolute value <100 mmHg. If hypotension was corrected within one minute it was considered a ‘success’. The doses for the subsequent patients were determined by responses to all previous patients, according to a variation of Narayana’s rule for the up-down sequential allocation method. ResultsThe 95% effective dose (ED95) and 50% effective dose (ED50) of phenylephrine was 41.7 µg (95% CI 33.8 to 49.6 µg) and 29.1 µg (95% CI 26.0 to 32.2 µg) respectively in the pre-eclampsia group, and 64.9 µg (95% CI 54.1 to 75.7 µg) and 47.3 µg (95% CI 39.7 to 54.9 µg) respectively in the normotensive group. The proportionate reduction in phenylephrine dose ranged from 33% (95% CI 18 to 44%) to 40% (95% CI 19 to 52%). ConclusionPatients with pre-eclampsia may need a 33% to 40% reduction in the first phenylephrine bolus dose, compared with patients with normotension, for the treatment of the first episode of post-spinal hypotension.

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.

Prophylactic Fixed-Rate Phenylephrine Versus Norepinephrine Infusion in the Prevention of Post-spinal Anesthesia Hypotension During Cesarean Delivery.

Background Maternal hypotension following spinal anesthesia can be actively countered by the use of vasopressors. Prophylactic infusion of vasopressors with a rescue bolus dosing was observed to be more effective for hemodynamic stability when compared to administering a bolus dose alone. Although phenylephrine is the recommended drug to treat spinal hypotension, many recent studies have focussed on the role of norepinephrine infusions during cesarean section. In this study, we compared prophylactic fixed-rate intravenous infusions of phenylephrine and norepinephrine during cesarean delivery under spinal anesthesia and the requirement of intraoperative provider-administered rescue bolus of phenylephrine needed to overcome post-spinal anesthesia hypotension. Methodology A total of 208 patients undergoing elective cesarean section under spinal anesthesia were randomly assigned to two groups (group P and group N). Group N included 104 patients who received norepinephrine infusion at a rate of 2.5 μg/minute (0.04 μg/kg/minute), and group P included 104 patients who received phenylephrine infusion at a rate of 50 μg/minute (0.8 μg/kg/minute)to treat spinal hypotension. The primary outcome of our study was to compare the reduction in the number and total dose of intraoperative provider-administered rescue bolus of phenylephrine needed to maintain systolic blood pressure. The secondary outcome of our study was to compare the neonatal outcome using umbilical venous blood gas sampling and Apgar score at one and five minutes. Results The total number of phenylephrine rescue bolus required to treat hypotension was significantly lower in group N (p = 0.0005) compared to group P. The neonatal outcome was similar between the two groups. Conclusions Prophylactic norepinephrine infusion when compared to prophylactic phenylephrine infusion is associated with a lesser requirement of rescue phenylephrine boluses.

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.

Randomized Clinical Study to Compare the Efficacy of Phenylephrine Bolus and Infusion for Maternal Hypotension and Neonatal Outcome during Lower Segment Cesarean Section under Spinal Anesthesia

Randomized Clinical Study to Compare the Efficacy of Phenylephrine Bolus and Infusion for Maternal Hypotension and Neonatal Outcome during Lower Segment Cesarean Section under Spinal Anesthesia

A COMPARATIVE STUDY OF MEPHENTERMINE AND PHENYLEPHRINE IN THE TREATMENT OF HYPOTENSION DURING SPINAL ANAESTHESIA FOR CAESAREAN SECTION

Purpose: To compare the effects of mephentermine and phenylephrine in maintaining arterial blood pressure in patients undergoing caesarean section under spinal anaesthesia who develop hypotension. Materials and method- This randomized study consisted of 42 parturient women who underwent elective caesarean section under spinal anaesthesia and developed hypotension during the operation. The patients were equally divided into 2 groups: Group I &amp; Group II. Participants in Group I received intravenous bolus of Phenylephrine 100 mcg whereas participants in Group II received intravenous bolus of Mephentermine 6 mg. Mean heart rate, systolic blood pressure (SBP), diastolic (DBP) and mean arterial pressure (MAP) were measured at baseline and then at 2 minutes intervals till 10th minute and thereafter at every 5 minutes till 30th minute and then at 45th, 60th, 75th, 90th and 120th minute. Results- Mean heart rate, SBP, DBP and MAP were comparable at baseline in both the groups. The reduction in mean heart rate after administration of a vasopressor was statistically signicant in Group I in comparison with Group II. Both Mephentermine &amp; Phenylephrine were efcacious in maintaining the SBP, DBP and MAP within the normal range i.e., 20% of the baseline value and no statistically signicant difference was observed between them. Both the vasopressors, Mephentermine and Phenylephrine have s Conclusion- imilar efcacy in maintaining post spinal maternal hypotension during caesarean section, although Phenylephrine causes reduction in heart rate which can be advantageous in patients with undesirable tachycardia. In addition to this, both the groups had no signicant adverse effects.

Comparative Study of Prophylactic Phenylephrine Bolus with Combined Phenylephrine and Glycopyrrolate Bolus in Maintaining the Haemodynamic in Caesarean Section under Spinal Anaesthesia

Comparative Study of Prophylactic Phenylephrine Bolus with Combined Phenylephrine and Glycopyrrolate Bolus in Maintaining the Haemodynamic in Caesarean Section under Spinal Anaesthesia

Incidence of bradycardia during noradrenaline or phenylephrine bolus treatment of postspinal hypotension in cesarean delivery: A randomized double-blinded controlled trial.

The treatment of choice for spinal anesthesia-induced hypotension during cesarean section is phenylephrine. As this vasopressor can cause reflex bradycardia, noradrenaline is a suggested alternative. This randomized double-blinded controlled trial included 76 parturients undergoing elective cesarean delivery under spinal anesthesia. Women received noradrenaline in bolus doses of 5mcg or phenylephrine in bolus doses of 100 mcg. These drugs were used intermittently and therapeutically to maintain systolic blood pressure ≥ 90% of its baseline value. The primary study outcome was bradycardia incidence (<60 bpm) with intermittent bolus administration of these drugs. Secondary outcomes included extreme bradycardia (<40 bpm), number of bradycardia episodes, hypertension (systolic blood pressure > 120% of baseline value), and hypotension (systolic blood pressure < 90% of baseline value and requiring vasopressor use). Neonatal outcomes per the Apgar scale and umbilical cord blood gas analysis were also compared. The incidence of bradycardia in both groups (51.4% and 70.3%, respectively; p=0.16) were not significantly different. No neonates had umbilical vein or artery pH values below 7.20. The noradrenaline group required more boluses than phenylephrine group (8 vs. 5; p=0.01). There was no significant intergroup difference in any of the other secondary outcomes. When administered in intermittent bolus doses for the treatment of postspinal hypotension in elective cesarean delivery, noradrenaline, and phenylephrine have a similar incidence of bradycardia. When treating hypotension related to spinal anesthesia in obstetric cases, strong vasopressors are commonly administered, thought these can also have side effects. This trial assessed bradycardia after bolus administration of noradrenaline or phenylephrine, and found no difference in risk for clinically meaningful bradycardia.

The effect of two dose phenylephrin for preventing hypotension during spinal anesthesia for cesarean delivery

Background: Spinal anesthesia-induced hypotension is one of the most complications which can cause many severe maternal and fetal complications. Therefore, the prevention and treatment of spinal anesthesia-induced hypotension in pregnant women undergoing cesarean delivery play an important role. The use of vasopressors is the most effective method of hypotensive prophylaxis and phenylephrine is currently the first-line vasopressor of choice to prevent this complication. The aim of this study is to evaluate the effectiveness and safety of two-dose phenylephrine for prevention of spinal anesthesia-induced hypotension during cesarean delivery. Materials and methods: In a randommized controlled clinical trial, 150 pregnants undregoing cesarean delivery with spinal anesthesia were randomly divided into three groups: Group I: as a control group without phenylephrine prophylaxis (n = 50), Group II: 50µg intravenously bolus phenylephrine (n = 50), and Group III: 75µg intravenously bolus phenylephrine (n = 50) immediately after induction of spinal anesthesia. Hypotension, defined decreasing systolic blood pressure &gt; 20% of baseline. The incidence of hypotension, levels of hypotension, maternal side effects and neonatal APGAR scores at 1 and 5 minutes. Results: The incidence of hypotension was 44%, the incidence of re-hypotension was 16%. Group III: the incidence of hypotension was 28%, the incidence of re-hypotension was 2%. The neonatal APGAR scores of the two groups at both 1 minute and 5 minutes was the same (p &gt; 0.05), all cases had APGAR &gt; 7. Conclusion: Phenylephrine intravenous bolus at doses of 50 µg and 75 µg are both effective for the prevention spinal anesthesia-induced hypotension for cesarean section. However, the 75 µg phenylephrine dose was more effective than the 50 µg dose because of lower rates of hypotension and recurrent hypotension (28% and 2% vs 44% and 16%, p &lt; 0.05). In addition, both groups of prophylactic phenylephrine didn’t cause detrimental adverses for parturients and their babies. Key words: Hypotensive prophylaxis, cesarean section, phenylephrin.