Anesthetic management for cesarean section in two parturient with ascending aortic aneurysm: a case-based discussion.

BACKGROUND: The anesthetic management of parturients with ascending aortic aneurysm for cesarean section can be particularly challenging, primarily because of increased risk for aortic dissection or aneurysm rupture. CASE PRESENTATION: We present some aspects of the anesthetic management of two parturients with ascending aortic aneurysm for cesarean sections; amongst, the use of remifentanil with its effects on patient and newborn. We emphasize the importance of a cardio-obstetric team in the context of preoperative planning of such patients. Also, we reviewed some literature on the anesthetic management with its effect on peri-operative hemodynamic stability. CONCLUSION: Maintaining hemodynamic stability is paramount in the prevention of the rupture or dissection of ascending aortic aneurysm during labor of parturient.

Emergency cesarean section of a patient with refractory status epilepticus: A case report of challenges during anesthesia.

INTRODUCTION: Maternal epilepsy is a critical condition that can significantly affect mothers and fetuses. Notably, the admission of a laboring mother with uncontrolled refractory status epilepticus (RSE) to the operating room presents a challenging scenario for anesthesiologists. THE MAIN SYMPTOMS OF THE PATIENT AND THE IMPORTANT CLINICAL FINDINGS: A 30-year-old primigravida was transferred to the operating room for an emergency cesarean section. Cesarean section was performed after a provisional diagnosis of preeclampsia was made. THE MAIN DIAGNOSES, THERAPEUTIC INTERVENTIONS, AND OUTCOMES: Cesarean section was performed under general anesthesia. During the postoperative period, the patient exhibited no seizure activity in the brain; however, she experienced mild cognitive dysfunction for up to 6 months postdelivery. The neonate were discharged without any complications. CONCLUSION: Inducing anesthesia in pregnant women with ongoing seizure activity are challenging; however, anesthesiologists provide judgment based on the balance between the safety of the mother and fetus and the balance between patient monitoring and the progression of anesthesia. This challenge can be addressed through multidisciplinary collaboration.

The Median Effective Dose of Intrathecal Hyperbaric Bupivacaine for Cesarean Section at Moderately High-Altitude.

Objective: Alterations in altitude can lead to an augmented requirement for local anesthesia among patients. Nevertheless, the necessity for an elevated dosage of local anesthetic for parturients at moderately high altitudes during spinal anesthesia for cesarean section remains uninvestigated. This up-down sequential study endeavors to determine the ED50 dose of bupivacaine required for spinal anesthesia during cesarean sections at moderately high-altitude. Methods: Thirty singleton parturients at moderately high altitude underwent elective cesarean section under combined spinal-epidural anesthesia. The up-and-down sequential method was employed, starting with an initial dose of 12mg (1.6mL) of 0.75% hyperbaric bupivacaine for the first participant. The dose for the next case was adjusted up or down by 0.75mg based on the effectiveness of the previous participant. Effectiveness was defined as the bilateral sensory block reaching T6 within 15 minutes after spinal anesthesia injection, without the need for additional epidural anesthesia before fetal delivery. The ED50 dose and 95% confidence interval were calculated using the Dixon sequential method and isotonic regression, respectively. The incidence of maternal hypotension, nausea, and vomiting during the study period was also recorded. Results: The ED50 of hyperbaric bupivacaine for spinal anesthesia in cesarean section was calculated as 8.23 mg (95% CI, 6.52-9.32 mg) using the Dixon up-and-down method. Further validation using isotonic regression yielded a value of 8.39 mg (95% CI, 7.48-9.30 mg), confirming the accuracy and sensitivity of the conclusion. During the operation, only 6 parturients experienced hypotension, and no adverse reactions such as nausea, vomiting, and shivering were observed. Conclusion: The ED50 dose of 0.75% hyperbaric bupivacaine for spinal anesthesia during cesarean section at moderately high altitude is 8.23 mg, which exceeds the ED50 dose typically required by parturients at low altitude. Comprehensive investigations are warranted to ascertain the ED90 or ED95 dose of local anesthetics for cesarean section at moderately high altitudes, thereby offering enhanced guidance for clinical practice.

Comparative Study between Paracervical Block and Non-Steroidal Anti Inflammatory Drug for Relief of Pain during Manual Vacuum Aspiration Procedure.

The incidence of first trimester pregnancy loss is around 10.0-20.0% of registered pregnancies. Manual vacuum aspiration is a safe, effective and acceptable option of treatment for patients diagnosed with first trimester pregnancy loss. Main disadvantage of MVA is the pain caused by manipulation of the cervix, the uterine suction and the cervical dilatation. This study showed the way how the pain and discomfort might be reduced. This was a cross-sectional comparative study was conducted at the obstetrics and Gynecological Department of Sadar hospital, Manikganj, Bangladesh from January 2017 to December 2017. All the consecutive women admitted and diagnosed as incomplete abortion, missed abortion and anembryonic pregnancy (blighted ovum) were included in this study. Sampling technique was purposive sampling. The objective of this study was to compare the effectiveness of paracervical block anesthesia with non-steroidal anti inflammatory drug (NSAID) for relief of pain during the manual vacuum aspiration procedure for the treatment of first trimester pregnancy loss. Total 120 cases were included in this study. Assigned study population were divided into two groups like Group A and Group B. 60 of the study population were included in Group A who were given paracervical block anesthesia 3 minutes before the procedure. Another 60 study population was included in Group B who was given diclofenac 75mg intramuscular injection, 30 minutes before the procedure. Both intraoperative and postoperative pain level was evaluated by using visual analog scale ranged from (0-10 points) 30 minutes after the procedure. At the same time the satisfaction level of the study population were measured by 5 points lickert scale. Regarding clinical profile of the study population it showed no significant difference in case of mean age, mean gestational age and mean duration of the procedure between two groups. The mean intraoperative pain score in Group A was 4.0±1.3, in Group B it was 5.4±1.5 (p=0.001) which was significant. So it showed that paracervical block anesthesia significantly reduced the pain in relation to diclofenac 75mg intramuscular injection. Mean postoperative pain level 30 minutes after procedure in Group A was 2.2±0.4 and in Group B was 2.4±0.4 (p=0.343), where post-operative pain is lower in Group A than Group B. Though this difference is not statistically significant (p=0.343). In Group A 73.0% (n=44) and in Group B 43.0% (n=26) study population were agreed that the procedure was easy. Most common adverse effect was epigastric pain which was 1.7% (n=1) in Group A and 10.0% (n=7) in Group B. Paracervical block significantly reduces intraoperative pain during Manual Vacuum Aspiration (MVA) procedure in the treatment of first trimester pregnancy loss in comparison to intramuscular injection of diclofenac. In conclusion it might be mentioned that regarding paracervical block anesthesia, efficacy is higher and side effects are less. Moreover paracervical block anesthesia is cost effective.

Management of sporadic intracranial vascular malformations in pregnancy: a retrospective analysis.

BACKGROUND: Sporadic intracranial vascular malformations can pose significant risk to parturients, and additional reports of management may inform patient care. Here we describe the peripartum management of parturients with intracranial vascular malformations. METHODS: After Institutional Review Board approval, we performed a retrospective analysis of parturients with a known sporadic intracranial vascular malformation including cavernous malformation, developmental venous anomaly, or arteriovenous malformation who delivered at our institution between 2007 and 2020. RESULTS: We identified 10 parturients (five cavernous malformations, three developmental venous anomalies, and two arteriovenous malformations) with 16 deliveries. Among all deliveries, 13 (81.3%) were cesarean deliveries without trial of labor; 11 of these (84.6%) received a single-shot spinal and two (15.4%) received an epidural for surgical anesthesia. Two deliveries (12.5%) began with attempted trial of labor but ultimately required cesarean delivery for failure to progress; one of these cases received epidural anesthesia and the other received combined spinal-epidural anesthesia. One delivery was via spontaneous vaginal delivery with epidural analgesia. Overall, our study's cesarean delivery rate was 93.8% and spontaneous vaginal delivery rate was 6.2%. Three of 16 pregnancies were complicated by seizure, obstructive hydrocephalus, or intracranial hemorrhage. There were no intensive care unit admissions or maternal deaths. CONCLUSIONS: In our case series of 16 deliveries, there were no complications directly resulting from neuraxial procedures. It remains unclear whether intracranial developmental venous anomalies or unruptured arteriovenous malformations impart increased risk during pregnancy. Antepartum planning with a multidisciplinary team approach enables risk stratification and optimal management.

Observational study of peripheral skin temperature changes following spinal anaesthesia for caesarean birth.

BACKGROUND: Spinal anaesthesia is widely used in obstetric anaesthesia practice but there is limited knowledge about the development of sympathetic blockade following spinal anaesthesia for caesarean birth. This study investigated the characteristics of sympathetic blockade by measuring peripheral skin temperature changes in the feet of patients given spinal anaesthesia for elective caesarean birth. METHODS: A prospective observational study was conducted involving 60 eligible parturients scheduled for elective caesarean birth with spinal anaesthesia. Skin temperature probes were attached to the dorsum of both feet, and temperature measurements were recorded every minute. The dose of spinal anaesthesia given, and other relevant patient data, were collected. RESULTS: All participants had successful spinal anaesthesia. Following spinal anaesthesia, a sustained rise in skin temperature of both feet was observed, indicating the presence of sympathetic blockade. The maximum rate of temperature increase occurred between 6 and 15 min after the intrathecal injection and plateaued from 22 min after the injection. Control participants did not show any changes in foot temperature. CONCLUSIONS: This study demonstrates that successful spinal anaesthesia for caesarean birth results in a consistent and reliable rise in skin temperature of the feet that is evident after six minutes from intrathecal injection. The observed temperature changes provide indirect objective evidence of bilateral sympathetic blockade. Measurement of feet skin temperatures may serve as an additional objective indicator of successful spinal anaesthesia, along with tests of lower limb motor block and sensory block height. These findings contribute to the understanding of sympathetic blockade during spinal anaesthesia.

A retrospective cohort study of the anesthetic management of postpartum tubal ligation.

BACKGROUND: Neuraxial anesthesia with reactivation of a labor epidural catheter is commonly utilized for postpartum tubal ligations (PPTL), although the optimal anesthetic approach is unknown. We assessed institutional anesthesia practices for PPTL, and evaluated the failure rates of reactivation of labor epidural catheters, de novo spinal anesthesia, and spinal anesthesia after failed blocks. METHODS: We conducted a single-center retrospective cohort analysis of 300 consecutive patients who underwent a PPTL and 100 having spinal anesthesia for cesarean delivery. Anesthetic management data (existing labor epidural catheter reactivation, de novo spinal anesthesia or general anesthesia) were collected from electronic medical records. Anesthetic block failure rates were determined for each anesthetic technique. RESULTS: The failure rate was 15% for de novo spinal anesthesia and 23% after failed reactivation of a labor epidural catheter or spinal anesthesia. The epidural catheter reactivation failure rate was 35%. The failure rate of spinal anesthesia for cesarean delivery was 4%. Drug dosage, epidural catheter use in labor, time since epidural catheter placement or delivery, labor neuraxial technique (combined spinal-epidural, epidural), supplemental top-up doses during labor, and anesthesiologist experience did not predict neuraxial anesthesia failures. CONCLUSIONS: Our analysis revealed an unexpectedly high neuraxial anesthesia failure rate even when de novo spinal anesthesia was used for PPTL. The results are consistent with other institutions' recent findings, and are higher than spinal anesthesia failure rates associated with cesarean delivery. Further studies are required to determine optimal anesthesia dosing strategies, and to understand the mechanisms behind high neuraxial anesthesia failures for PPTL.

A narrative review of the literature relevant to obstetric anesthesiologists: the 2023 Gerard W. Ostheimer lecture.

This narrative review of the 2023 Gerard W. Ostheimer lecture presented at the Society for Obstetric Anesthesia and Perinatology 2023 annual meeting summarizes 2022 literature relevant to obstetric anesthesiologists. ANTENATAL STUDIES: Neonatal morbidity is reduced with antenatal maternal buprenorphine compared with methadone for treatment of opioid use disorder. Antenatal pregnancy allergy testing is safe and feasible. ANALGESIA AND ANESTHESIA STUDIES: Intrathecal (IT) 3% chloroprocaine for cervical cerclage results in faster sensory block resolution and discharge readiness compared with bupivacaine. The ED90 of 3% chloroprocaine (with IT fentanyl 10 µg) is 49.5 mg. Dural puncture epidural technique does not improve the quality of labor analgesia in obese parturients compared with epidural analgesia. Low- (>0.08 to ≤0.1%) and ultra-low (<0.08%) concentrations of bupivacaine for epidural analgesia maintenance result in similar maternal and neonatal outcomes. Lower doses of first line uterotonic agents are non-inferior to higher doses (oxytocin 0.5 IU vs. 5 IU and carbetocin 20 vs. 100 µg) in patients at low risk for postpartum hemorrhage. Supplemental analgesia or conversion to general anesthesia is necessary in approximately 15% of elective cesarean deliveries. Intravenous dexamethasone improves analgesia outcomes, however optimal dosing and timing remain unclear; it may induce neonatal hypoglycemia in the setting of gestational diabetes. POSTPARTUM STUDIES: A core outcome set may help evaluate enhanced recovery protocol implementation. History of migraine and accidental dural puncture (ADP) above the L3 level are associated with epidural blood patch (EBP) failure and ADP at or below L3 and >48 h interval between ADP and EBP are associated with success.

The 90% effective dose of intrathecal hyperbaric bupivacaine for Cesarean delivery under combined spinal-epidural anesthesia in parturients with super obesity: an up-down sequential allocation study.

PURPOSE: To determine the 90% effective dose (ED90) of intrathecal hyperbaric bupivacaine for Cesarean delivery under combined spinal-epidural anesthesia (CSE) in parturients with super obesity (body mass index [BMI] ≥ 50 kg·m-2). METHODS: We enrolled parturients with BMI ≥ 50 kg·m-2 with term, singleton vertex pregnancies undergoing elective Cesarean delivery under CSE. An independent statistician generated the 0.75% hyperbaric bupivacaine dosing regimen in increments of 0.75 mg using a biased-coin up-down sequential allocation technique. This was combined with 15 µg fentanyl, 150 µg morphine, and normal saline to a volume of 2.05 mL. The initial and maximum doses were 9.75 mg and 12 mg, respectively. Participants, clinical team, and outcome assessors were blinded to the dose. The primary outcome was block success, defined as T6 block to pinprick within ten minutes and no intraoperative analgesic supplementation within 90 min of spinal injection. We determined the ED90 using logistic regression. RESULTS: We enrolled 45 parturients and included 42 in the analysis. All doses achieved a T6 level within ten minutes, and the primary outcome occurred in 0/1 (0%) of the 9.75-mg doses, 2/3 (67%) of the 10.5-mg doses, 21/27 (78%) of the 11.25-mg doses, and 11/11 (100%) of the 12-mg doses. The ED90 of hyperbaric bupivacaine was 11.56 mg (95% confidence interval, 11.16 to 11.99). Four parturients (9.5%) had sensory level higher than T2, but none was symptomatic or required general anesthesia. CONCLUSION: The estimated ED90 of hyperbaric bupivacaine with fentanyl and morphine in parturients with super obesity undergoing Cesarean delivery under CSE was approximately 11.5 mg. STUDY REGISTRATION: ClinicalTrials.gov (NCT03781388); first submitted 18 December 2018.

RéSUMé: OBJECTIF: Notre objectif était de déterminer la dose efficace à 90 % (DE90) de bupivacaïne hyperbare intrathécale pour l'accouchement par césarienne sous péri-rachianesthésie combinée (PRC) chez les personnes parturientes atteintes de super obésité (indice de masse corporelle [IMC] ≥ 50 kg·m−2). MéTHODE: Nous avons recruté des personnes parturientes ayant un IMC ≥ 50 kg·m−2 présentant des grossesses uniques à terme, en présentation céphalique et bénéficiant d'un accouchement par césarienne programmée sous PRC. Un·e statisticien·ne indépendant·e a généré le schéma posologique de bupivacaïne hyperbare à 0,75 % par incréments de 0,75 mg à l'aide d'une technique d'allocation séquentielle en escalier. La bupivacaïne a été combinée à 15 µg de fentanyl, 150 µg de morphine et à une solution physiologique salée jusqu'à un volume de 2,05 mL. Les doses initiale et maximale étaient respectivement de 9,75 mg et 12 mg. Les participant·es, l'équipe clinique et les personnes évaluant les résultats n'avaient pas connaissance de la dose. Le critère d'évaluation principal était la réussite du bloc, définie comme un bloc à T6 à la piqûre dans les dix minutes et aucune supplémentation analgésique peropératoire dans les 90 minutes suivant l'injection rachidienne. Nous avons déterminé la DE90 à l'aide d'une méthode de régression logistique. RéSULTATS: Nous avons recruté 45 personnes parturientes et en avons inclus 42 dans l'analyse. Toutes les doses ont atteint le niveau T6 en dix minutes, et le critère d'évaluation principal a été obtenu pour 0/1 (0 %) des doses de 9,75 mg, 2/3 (67 %) des doses de 10,5 mg, 21/27 (78 %) des doses de 11,25 mg et 11/11 (100 %) des doses de 12 mg. La DE90 de bupivacaïne hyperbare était de 11,56 mg (intervalle de confiance à 95 %, 11,16 à 11,99). Quatre personnes parturientes (9,5 %) ont affiché un niveau sensoriel supérieur à T2, mais aucune n'était symptomatique ni n'a nécessité d'anesthésie générale. CONCLUSION: La DE90 estimée de bupivacaïne hyperbare avec fentanyl et morphine chez les personnes parturientes hyperobèses bénéficiant d'une césarienne sous PRC était d'environ 11,5 mg. ENREGISTREMENT DE L'éTUDE: ClinicalTrials.gov (NCT03781388); soumis pour la première fois le 18 décembre 2018.

Paracervical block before laparoscopic total hysterectomy: A randomized controlled trial.

OBJECTIVE: To test the hypothesis that paracervical block with 0.5 % bupivacaine decreases postoperative pain after total laparoscopic hysterectomy (TLH). MATERIALS AND METHOD: This randomized double-blind placebo control trial included 152 women. We injected 10 mL 0.5 % bupivacaine (study group, n = 75) or 10 mL normal saline (control group, n = 77) at the 3 and 9 o'clock positions of the uterine cervix. The primary outcome was the visual analog scale score (VAS) determined 1 h (h) postoperatively. RESULTS: The 152 patients did not differ in their baseline demographics or perioperative characteristics. The mean VAS 1 h postoperatively was significantly lower in the study group than in controls (5.7 ± 1.2 vs. 6.8 ± 1.1, P < 0.001). The average VAS at 30 min, 3 h, and 6 h postoperatively was also significantly lower in the study group. Patients in the study group had a significantly lower analgesic requirement than did controls during the first 24 h postoperatively (6 [7.8 %] vs. 16 [21 %], P = 0.021). Total QoR-40 questionnaire scores were higher in patients who received bupivacaine. CONCLUSION: Paracervical bloc with 0.5 % bupivacaine just before TLH is an effective and safe method to reduce pain and lower postoperative analgesic requirement. URL LINK THAT LEADS DIRECTLY TO THE TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT05341869?cond=NCT05341869&draw=2&rank=1.

Norepinephrine versus phenylephrine on cerebral tissue oxygen saturation during prophylactic infusion to prevent spinal hypotension for Caesarean birth.

BACKGROUND: Phenylephrine may cause a reduction in maternal cerebral tissue oxygen saturation (SctO2) during Caesarean birth to prevent spinal hypotension; however, the effect of norepinephrine has not been assessed. We hypothesized that norepinephrine was more effective than phenylephrine in maintaining SctO2 when preventing spinal hypotension during Caesarean birth. METHODS: We conducted a randomized, double-blind, controlled study. Sixty patients were randomly assigned to prophylactic norepinephrine or phenylephrine to maintain blood pressure during spinal anesthesia for Caesarean birth. SctO2, systolic blood pressure, and heart rate were recorded. The primary outcome was the incidence of a 10% reduction of intraoperative SctO2 from baseline or more during Caesarean birth. RESULTS: The norepinephrine group had a lower incidence of more than 10% reduction of intraoperative SctO2 from baseline than that of the phenylephrine group (13.3% vs 40.0%, P = .02). The change in SctO2 after 5 minutes of norepinephrine infusion was higher than that after phenylephrine infusion (-3.4 ±â€…4.7 vs -6.2 ±â€…5.6, P = .04). The change in SctO2 after 10 minutes of norepinephrine infusion was higher than that after phenylephrine infusion (-2.5 ±â€…4.4 vs -5.4 ±â€…4.6, P = .006). The norepinephrine group showed greater left- and right-SctO2 values than the phenylephrine group at 5 to 10 minutes. However, the change in systolic blood pressure was comparable between the 2 groups. CONCLUSION: Norepinephrine was more effective than phenylephrine in maintaining SctO2 when preventing spinal hypotension during Caesarean birth. However, the changes in clinical outcomes caused by differences in SctO2 between the 2 medications warrant further studies.

Is crystalloid co-loading necessary to prevent spinal hypotension during elective cesarean delivery? A randomized double-blind trial.

BACKGROUND: Hypotension is common during spinal anesthesia for cesarean delivery. Preventive strategies include fluid loading and phenylephrine. We hypothesized that if prophylactic phenylephrine infusion is used, omission of fluid loading would be non-inferior to fluid co-loading in maintaining cardiac output. We assumed that if there was a difference, the increase in cardiac output would be greater in the no-loading than in the co-loading group. METHODS: Term pregnant women scheduled for elective cesarean delivery were randomized to receive 1 L crystalloid co-loading or maintenance fluids only. Phenylephrine was titrated to maintain blood pressure. Changes in cardiac output following spinal anesthesia were the primary outcome. The study was powered as a non-inferiority trial, allowing the no-loading arm to have a 50% greater change in cardiac output. Heart rate, dose of phenylephrine, occurrence of nausea and vomiting, Apgar scores and neonatal acid base status were secondary outcomes. RESULTS: Data from 63 women were analyzed. In contrast to our hypothesis, there was 33% less increase in cardiac output with no loading (ratio 0.67, 95% CI 0.15 to 1.36), and 60% greater reduction of cardiac output with no loading (ratio 1.6, 95% CI 1.0 to 2.7). Total dose of phenylephrine was higher in the no-loading group. There may be a less favorable neonatal acid base status without volume loading. CONCLUSION: Omission of crystalloid co-loading leads to a decrease in cardiac output which has a potentially unfavorable impact on neonatal acid base status. We conclude that crystalloid co-loading may be useful in the presence of phenylephrine infusion.

The importance of simulation-based multi professional training in obstetric anesthesia: an update.

PURPOSE OF REVIEW: Simulation-based training remains an integral component of medical education by providing a well tolerated, controlled, and replicable environment for healthcare professionals to enhance their skills and improve patient outcomes. Simulation technology applied to obstetric anesthesiology continues to evolve as a valuable tool for the training and assessment of the multidisciplinary obstetric care team. RECENT FINDINGS: Simulation-based technology has continued to play a role in training and assessment, including recent work on interdisciplinary communication, recognition, and management of obstetric hemorrhage, and support in the low or strained resource setting. The COVID-19 pandemic has accelerated the evolution of simulation-based training away from a reliance on in-situ or high-fidelity manikin-based approaches toward an increasing utilization of modalities that allow for remote or asynchronous training. SUMMARY: The evolution of simulation for interdisciplinary training and assessment in obstetric anesthesia has accelerated, playing a greater role in aspects of communication, management of hemorrhage and supporting low or strained resource settings. Augmented reality, virtual reality and mixed reality have advanced dramatically, spurred on by the need for remote and asynchronous simulation-based training during the pandemic.

Effect of phenylephrine rescue injection on hypotension after spinal anaesthesia for caesarean delivery when guided by both heart rate and SBP during an early warning window: A randomised controlled trial.

BACKGROUND: Spinal anaesthesia is now the most common technique for caesarean delivery. However, because of the intermittent nature of noninvasive blood pressure (NIBP) measurements, maternal blood pressure may become hypotensive between the measurements. There is thus an inbuilt delay before the anaesthesiologist can intervene to counteract the hypotension. Based on the principle that changes in blood pressure can induce compensatory changes in the heart rate (HR), combining the NIBP with real-time HR, we designed two warning windows to predict hypotension and hypertension. OBJECTIVE: To evaluate whether phenylephrine administration guided by these warning windows would help maintain haemodynamic stability. SETTING: A teaching hospital. DESIGN: A randomised controlled trial. PATIENTS: One hundred and ten pregnant women scheduled for elective caesarean delivery were enrolled, from which, after exclusions, 86 were eligible for the study. INTERVENTIONS: All eligible patients received a continuous intravenous infusion of phenylephrine as soon as spinal anaesthesia was initiated. Thereafter, patients were randomly assigned to two groups. In the test group (Win-Group): rescue phenylephrine administration was triggered by an early warning window of HR above 100 beats per minute (bpm) and SBP 90 to 110 mmHg; pausing the infusion phenylephrine was triggered by a HR lower than 60 bpm and SBP greater than 90 mmHg. In the control group, phenylephrine was guided by BP only when it appeared on the monitor: SBP less than 90 mmHg was the trigger for administering rescue phenylephrine; SBP greater than 110 mmHg was the trigger for pausing the phenylephrine infusion. MAIN OUTCOME MEASURES: The primary outcome was incidence of hypotension. Secondary outcomes were the incidence of hypertension and other adverse haemodynamic events. RESULTS: The incidence of hypotension was significantly lower in the Win-Group than in the BP-Group (27.8 vs. 66.7%, P  = 0.001). The minimum SBP was significantly higher in Win-Group than in BP-Group (93.9 ±â€Š9.49 vs. 86.7 ±â€Š11.16 mmHg, P   =  0.004). There was no significant difference in the incidence of hypertension between groups. CONCLUSION: After spinal anaesthesia for caesarean delivery, when phenylephrine infusion is guided by HR along with BP from a warning window it effectively reduces the incidence of hypotension without any significant effect on incidence of hypertension. TRIAL REGISTRATION: Chictr.org.cn; Identifier: ChiCTR 2100041812.