Dose-Response Study of Phenylephrine for Preventing Spinal-Induced Hypotension During Cesarean Delivery with Combined Spinal-Epidural Anesthesia Under the Effect of Prophylactic Intravenous Ondansetron.

Background: Ondansetron reduces the median effective dose (ED50) of prophylactic phenylephrine to prevent spinal-induced hypotension (SIH) during cesarean delivery. However, the exact dose response of phenylephrine in combination with prophylactic ondansetron for preventing SIH is unknown. Therefore, this study aimed to determine the dose-response of phenylephrine to prevent SIH in cesarean delivery when 4 mg of ondansetron was used as a preventive method. Methods: A total of 80 parturients were enrolled and divided randomly into four groups (n = 20 in each group) who received either 0.2, 0.3, 0.4, or 0.5 µg/kg/min of prophylactic phenylephrine. Ten minutes before the initiation of spinal induction, 4 mg prophylactic ondansetron was administered. The effective dose of prophylactic phenylephrine was defined as the dose required to prevent hypotension after the period of intrathecal injection and up to neonatal delivery. The ED50 and ED90 of prophylactic phenylephrine and 95% confidence intervals (95% CI) were calculated using probit analysis. Results: The ED50 and ED90 for prophylactic phenylephrine to prevent SIH were 0.25 (95% CI, 0.15 to 0.30), and 0.45 (95% CI, 0.39 to 0.59) µg/kg/min, respectively. No significant differences were observed in the side effects and neonatal outcomes between the four groups. Conclusion: The administration of 4 mg of prophylactic ondansetron was associated with an ED50 of 0.25 (95% CI, 0.15~0.30) and ED90 of 0.45 (95% CI, 0.39~0.59) µg/kg/min for phenylephrine to prevent SIH.

Effect of subclavian vein diameter combined with perioperative fluid therapy on preventing post-induction hypotension in patients with ASA status I or II.

BACKGROUND: Perioperative hypotension is frequently observed following the initiation of general anesthesia administration, often associated with adverse outcomes. This study assessed the effect of subclavian vein (SCV) diameter combined with perioperative fluid therapy on preventing post-induction hypotension (PIH) in patients with lower ASA status. METHODS: This two-part study included patients aged 18 to 65 years, classified as ASA physical status I or II, and scheduled for elective surgery. The first part (Part I) included 146 adult patients, where maximum SCV diameter (dSCVmax), minimum SCV diameter (dSCVmin), SCV collapsibility index (SCVCI) and SCV variability (SCVvariability) assessed using ultrasound. PIH was determined by reduction in mean arterial pressure (MAP) exceeding 30% from baseline measurement or any instance of MAP < falling below 65 mmHg for ≥ a duration of at least 1 min during the period from induction to 10 min after intubation. Receiver Operating Characteristic (ROC) curve analysis was employed to determine the predictive values of subclavian vein diameter and other relevant parameters. The second part comprised 124 adult patients, where patients with SCV diameter above the optimal cutoff value, as determined in Part I study, received 6 ml/kg of colloid solution within 20 min before induction. The study evaluated the impact of subclavian vein diameter combined with perioperative fluid therapy by comparing the observed incidence of PIH after induction of anesthesia. RESULTS: The areas under the curves (with 95% confidence intervals) for SCVCI and SCVvariability were both 0.819 (0.744-0.893). The optimal cutoff values were determined to be 45.4% and 14.7% (with sensitivity of 76.1% and specificity of 86.7%), respectively. Logistic regression analysis, after adjusting for confounding factors, demonstrated that both SCVCI and SCVvariability were significant predictors of PIH. A threshold of 45.4% for SCVCI was chosen as the grouping criterion. The incidence of PIH in patients receiving fluid therapy was significantly lower in the SCVCI ≥ 45.4% group compared to the SCVCI < 45.4% group. CONCLUSIONS: Both SCVCI and SCVvariability are noninvasive parameters capable of predicting PIH, and their combination with perioperative fluid therapy can reduce the incidence of PIH.

Evaluation of the early use of norepinephrine in major abdominal surgery on medical and surgical postoperative complications: study protocol for a randomised controlled trial (EPON STUDY).

BACKGROUND: Post-induction anaesthesia often promotes intraoperative hypotension (IOH) that can worsen postoperative outcomes. This study aims to assess the benefit of norepinephrine versus ephedrine at the induction of anaesthesia to prevent postoperative complications following major abdominal surgery by preventing IOH. METHODS AND ANALYSIS: The EPON STUDY is a prospective single-centre randomised controlled trial with the planned inclusion of 500 patients scheduled for major abdominal surgery at the Amiens University Hospital. The inclusion criteria are patients aged over 50 years weighing more than 50 kg with an American Society of Anesthesiologists physical status score of ≥2 undergoing major abdominal surgery under general anaesthesia. Patients are allocated either to the intervention group (n=250) or the standard group (n=250). In the intervention group, the prevention of post-induction IOH is performed with norepinephrine (dilution to 0.016 mg/mL) using an electric syringe pump at a rate of 0.48 mg/h (30 mL/h) from the start of anaesthesia and then titrated to achieve the haemodynamic target. In the control group, the prevention of post-induction IOH is performed with manual titration of ephedrine, with a maximal dose of 30 mg, followed by perfusion with norepinephrine. In both groups, the haemodynamic target to maintain is a mean arterial pressure (MAP) of 65 mm Hg or 70 mm Hg for patients with a medical history of hypertension. An intention-to-treat analysis will be performed. The primary outcome is the Clavien-Dindo score assessed up to 30 days postoperatively. The secondary endpoints are the length of hospital stay and length of stay in an intensive care unit/postoperative care unit; postoperative renal function; postoperative cardiovascular, respiratory, neurological, haematological and infectious complications at 1 month; and volume of intraoperative vascular filling and mortality at 1 month. ETHICS AND DISSEMINATION: Ethical approval was obtained from the committee of protection of the persons of Ile de France in May 2021 (number 21 05 41). The authors will be involved in disseminating the research findings (through attending conferences and co-authoring papers). The results of the study will be disseminated via peer-reviewed publications and presentations at national and international conferences. TRIAL REGISTRATION NUMBER: NCT05276596.

Machine learning model based on RCA-PDCA nursing methods and differentiating factors to predict hypotension during cesarean section surgery.

BACKGROUND: Intraoperative hypotension during cesarean section has become a serious complication for maternal and fetal healthy. It is commonly encountered by subarachnoid anesthesia. However, currently used control methods have varying degrees of side effects, such as drugs. The Root Cause Analysis (RCA) - Plan, Do, Check, Act (PDCA) is a new model of care that identifies the root causes of problems. The study aimed to demonstrate the usefulness of RCA-PDCA nursing methods in preventing intraoperative hypotension during cesarean section and to predict the occurrence of intraoperative hypotension through a machine learning model. METHODS: Patients who underwent cesarean section at Traditional Chinese Medicine of Southwest Medical University from January 2023 to December 2023 were retrospectively screened, and the data of their gestational times, age, height, weight, history of allergies, intraoperative vital signs, fetal condition, operative time, fluid out and in, adverse effects, use of vasopressor drugs, anxiety-depression-pain scores, and satisfaction were collected and analyzed. The statistically different features were screened and five machine learning models were used as predictive models to assess the usefulness of the RCA-PDCA model of care. RESULTS: (1) Compared with the general nursing model, the RCA-PDCA nursing model significantly reduces the incidence of intraoperative hypotension and postoperative complications in cesarean delivery, and the patient experience is comfortable and satisfactory. (2) Among the five machine learning models, the RF model has the best predictive performance, and the accuracy of the random forest model in preventing intraoperative hypotension is as high as 90%. CONCLUSION: Through computer machine learning model analysis, we prove the importance of the RCA-PDCA nursing method in the prevention of intraoperative hypotension during cesarean section, especially the Random Forest model which performed well and promoted the application of artificial intelligence computer learning methods in the field of medical analysis.

Effect of Fluid Therapy in Early Morning on the Incidence of Post-Induction Hypotension During Non-Cardiac Surgery After Noon: A Single-Center Retrospective Study.

Purpose: Post-induction hypotension (PIH) is a common clinical phenomenon linked to increased morbidity and mortality in various non-cardiac surgeries. Patients with surgery in the afternoon may have preoperative hypovolemia caused by prolonged fasting and dehydration, which increases the risk of hypotension during the induction period. However, studies on the fluid therapy in early morning combating PIH remain inadequate. Therefore, we aimed to investigate the influence of prophylactic high-volume fluid in the early morning of the operation day on the incidence of PIH during non-cardiac surgery after noon. Patients and Methods: We reviewed the medical records of patients who underwent non-cardiac surgery after noon between October 2021 and October 2022. The patients were divided into two groups based on whether they received a substantial volume of intravenous fluid (high-volume group) or not (low-volume group) in the early morning of the surgery day. We investigated the incidence of PIH and intraoperative hypotension (IOH) as well as the accumulated duration of PIH in the first 15 minutes. In total, 550 patients were included in the analysis. Results: After propensity score matching, the incidence of PIH was 39.7% in the high-volume group and 54.1% in the low-volume group. Multivariate logistic regression analysis showed that patients in the high-volume group had lower incidence of hypotension after induction compared with the low-volume group (odds ratio, 0.55; 95% CI, 0.34-0.89; p = 0.016). The high-volume fluid infusion in the preoperative morning was significantly correlated with the decreased duration of PIH (p = 0.013), but no statistical difference was observed for the occurrence of IOH between the two groups (p = 0.075). Conclusion: The fluid therapy of more than or equal to 1000 mL in the early morning of the surgery day was associated with a decreased incidence of PIH compared with the low-volume group in patients undergoing non-cardiac surgery after noon.

Processed electroencephalography-guided general anesthesia and norepinephrine requirements: A randomized trial in patients having vascular surgery.

STUDY OBJECTIVE: Processed electroencephalography (pEEG) may help clinicians optimize depth of general anesthesia. Avoiding excessive depth of anesthesia may reduce intraoperative hypotension and the need for vasopressors. We tested the hypothesis that pEEG-guided - compared to non-pEEG-guided - general anesthesia reduces the amount of norepinephrine needed to keep intraoperative mean arterial pressure above 65 mmHg in patients having vascular surgery. DESIGN: Randomized controlled clinical trial. SETTING: University Medical Center Hamburg-Eppendorf, Hamburg, Germany. PATIENTS: 110 patients having vascular surgery. INTERVENTIONS: pEEG-guided general anesthesia. MEASUREMENTS: Our primary endpoint was the average norepinephrine infusion rate from the beginning of induction of anesthesia until the end of surgery. MAIN RESULT: 96 patients were analyzed. The mean ± standard deviation average norepinephrine infusion rate was 0.08 ± 0.04 µg kg-1 min-1 in patients assigned to pEEG-guided and 0.12 ± 0.09 µg kg-1 min-1 in patients assigned to non-pEEG-guided general anesthesia (mean difference 0.04 µg kg-1 min-1, 95% confidence interval 0.01 to 0.07 µg kg-1 min-1, p = 0.004). Patients assigned to pEEG-guided versus non-pEEG-guided general anesthesia, had a median time-weighted minimum alveolar concentration of 0.7 (0.6, 0.8) versus 0.8 (0.7, 0.8) (p = 0.006) and a median percentage of time Patient State Index was <25 of 12 (1, 41) % versus 23 (3, 49) % (p = 0.279). CONCLUSION: pEEG-guided - compared to non-pEEG-guided - general anesthesia reduced the amount of norepinephrine needed to keep mean arterial pressure above 65 mmHg by about a third in patients having vascular surgery. Whether reduced intraoperative norepinephrine requirements resulting from pEEG-guided general anesthesia translate into improved patient-centered outcomes remains to be determined in larger trials.

Hypotension prediction index guided goal-directed therapy to reduce postoperative acute kidney injury during major abdominal surgery: study protocol for a multicenter randomized controlled clinical trial.

BACKGROUND: Acute kidney injury (AKI) is a significant postoperative complication associated with increased mortality and hospital costs. Hemodynamic strategies, such as goal-directed therapy, might reduce AKI risk. Predicting and proactively managing intraoperative hypotension may be helpful. This trial aims to investigate if a preemptive hemodynamic strategy guided by the hypotension prediction index (HPI) can decrease the incidence of moderate-to-severe AKI within 30 days following major elective abdominal surgery. METHODS: This is an open-label, controlled, multicenter, randomized clinical trial that involves daily patient follow-up until hospital discharge. Inclusion criteria are patients aged over 65 and/or categorized as ASA III or IV physical status, undergoing major elective abdominal surgery (general, urological, or gynecological procedures) via laparoscopic or open approach under general or combined anesthesia. INTERVENTION: In the intervention group, hemodynamic management will be based on the HPI and the advanced functional hemodynamic variables provided by the Hemosphere platform and the AcumenIQ® sensor (Edwards Lifesciences). The primary outcome is the incidence of moderate-to-severe AKI within 7 days post-surgery. Secondary outcomes include postoperative complications and 30-day mortality. DISCUSSION: This study explores the potential of HPI-guided hemodynamic management in reducing AKI after major elective abdominal surgery, with implications for postoperative outcomes and patient care. TRIAL REGISTRATION: ClinicalTrials.gov NCT05569265. Registered on October 6, 2022.

Effect of Remimazolam- versus Propofol-Based Total Intravenous General Anesthesia on Intraoperative Hemodynamic Stability for Major Spine Surgery in the Prone Position: A Randomized Controlled Trial.

Background and Objectives: Remimazolam offers advantages over propofol in terms of hemodynamic stability. However, it remains unclear whether remimazolam-based total intravenous anesthesia (TIVA) can reduce intraoperative hypotension compared to propofol-based TIVA, especially after prone positioning. In this study, we compared the effects of remimazolam- and propofol-based TIVA on intraoperative hemodynamic stability in patients undergoing surgery in the prone position. Materials and Methods: This study randomly assigned patients undergoing major spinal surgery in the prone position to the propofol or remimazolam group. Target-controlled infusion (2-3.5 µg/mL for induction and 2-3 µg/mL for maintenance) was used in the propofol group and continuous infusion (6 mg/kg/h for induction and 1-2 mg/kg/h for maintenance) was used in the remimazolam group; target-controlled infusion (3-5 ng/mL) of remifentanil was performed in both groups. The primary outcomes were the incidence of hypotensive episodes during the first hour after prone positioning. The secondary outcomes included the incidence of severe hypotension and the total amount of inotropic or vasopressor medication. Systolic and mean arterial pressure, heart rate, cardiac index and output, stroke volume, stroke volume variation, and pleth variability index were also evaluated. These variables were recorded per minute for the first 10 min after prone positioning, and every 10 min thereafter. Results: The study enrolled 94 patients (47 patients in each group). The incidence of hypotension or severe hypotension did not differ significantly between the two groups during the first hour after prone positioning. The total amount of ephedrine administered during the first hour after prone positioning was lesser (p = 0.020) and the mean arterial pressure during the initial 10 min after prone positioning was higher in the remimazolam group (p = 0.003). Conclusions: Our study uncovered no significant differences in the incidence of hypotension between remimazolam- and propofol-based TIVA in patients undergoing major spine surgery in prone position.

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.

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.

Effect of different targets of goal-directed fluid therapy on intraoperative hypotension and fluid infusion in robot-assisted laparoscopic gynecological surgery: a randomized non-inferiority trial.

Carotid corrected flow time (FTc) and tidal volume challenge pulse pressure variation (VtPPV) are useful clinical parameters for assessing volume status and fluid responsiveness in robot-assisted surgery, but their usefulness as goal-directed fluid therapy (GDFT) targets is unclear. We investigated whether FTc or VtPPV as targets are inferior to PPV in GDFT. This single-center, prospective, randomized, non-inferiority study included 133 women undergoing robot-assisted laparoscopic gynecological surgery in the modified head-down lithotomy position. Patients were equally divided into three groups, and the GDFT protocol was guided by FTc, VtPPV, or PPV during surgery. Primary outcomes were non-inferiority of the time-weighted average of hypotension, intraoperative fluid volume, and urine output. Secondary outcomes were optic nerve sheath diameter (ONSD) pre- and post-operatively and creatinine and blood urea nitrogen preoperatively and on day 1 post-operatively. No significant differences were observed in intraoperative hypotension index, infusion and urine volumes, and ONSD post-operatively between the FTc and VtPPV groups and the PPV group. No differences in serum creatinine and urea nitrogen levels were identified between the FTc and VtPPV groups preoperatively, but on day 1 post-operatively, the urea nitrogen level in the FTc group was higher than that in the PPV group (4.09 ± 1.28 vs. 3.0 ± 1.1 mmol/L, 1.08 [0.59, 1.58], p < 0.0001), and the difference from the preoperative value was smaller than that in the PPV group (- 2 [- 2.97, 1.43] vs. - 1.34 [- 1.9, - 0.67], p = 0.004). FTc- or VtPPV-guided protocols are not inferior to that of PPV in GDFT during robot-assisted laparoscopic surgery in the modified head-down lithotomy position.Trial registration: Chinese Clinical Trial Registry (ChiCTR2200064419).

Intraoperative hypotension and postoperative acute kidney injury: A systematic review.

BACKGROUND: There is no consensus regarding safe intraoperative blood pressure thresholds that protect against postoperative acute kidney injury (AKI). This review aims to examine the existing literature to delineate safe intraoperative hypotension (IOH) parameters to prevent postoperative AKI. METHODS: PubMed, Cochrane Central, and Web of Science were systematically searched for articles published between 2015 and 2022 relating the effects of IOH on postoperative AKI. RESULTS: Our search yielded 19 articles. IOH risk thresholds ranged from <50 to <75 â€‹mmHg for mean arterial pressure (MAP) and from <70 to <100 â€‹mmHg for systolic blood pressure (SBP). MAP below 65 â€‹mmHg for over 5 â€‹min was the most cited threshold (N â€‹= â€‹13) consistently associated with increased postoperative AKI. Greater magnitude and duration of MAP and SBP below the thresholds were generally associated with a dose-dependent increase in postoperative AKI incidence. CONCLUSIONS: While a consistent definition for IOH remains elusive, the evidence suggests that MAP below 65 â€‹mmHg for over 5 â€‹min is strongly associated with postoperative AKI, with the risk increasing with the magnitude and duration of IOH.

Effect of a Salt Substitute on Incidence of Hypertension and Hypotension Among Normotensive Adults.

BACKGROUND: Reports on the effects of salt substitution among individuals with normal blood pressure are scarce and controversial. OBJECTIVES: This study sought to assess the effects of a salt substitute (62.5% NaCl, 25% KCl, and 12.5% flavorings) on incidence of hypertension and hypotension among older adults with normal blood pressure. METHOD: A post hoc analysis was conducted among older adults with normal blood pressure participating in DECIDE-Salt, a large, multicenter, cluster-randomized trial in 48 elderly care facilities for 2 years. We used the frailty survival model to compare risk of incident hypertension and the generalized linear mixed model to compare risk of hypotension episodes. RESULTS: Compared with usual salt group (n = 298), the salt substitute group (n = 313) had a lower hypertension incidence (11.7 vs 24.3 per 100 person-years; adjusted HR: 0.60; 95% CI: 0.39 to 0.92; P = 0.02) but did not increase incidence of hypotension episodes (9.0 vs 9.7 per 100 person-years; P = 0.76). Mean systolic/diastolic blood pressure did not increase from the baseline to the end of intervention in the salt substitute group (mean changes: -0.3 ± 11.9/0.2 ± 7.1 mm Hg) but increased in the usual salt group (7.0 ± 14.3/2.1 ± 7.5 mm Hg), resulting in a net reduction of -8.0 mm Hg (95% CI: -12.4 to -3.7 mm Hg) in systolic and -2.0 mm Hg (95% CI: -4.1 to 0.1 mm Hg) in diastolic blood pressure between intervention groups. CONCLUSIONS: In Chinese older adults with normal blood pressure, replacing usual salt with a salt substitute may reduce the incidence of hypertension without increasing hypotension episodes. This suggests a desirable strategy for population-wide prevention and control of hypertension and cardiovascular disease, deserving further consideration in future studies. (Diet Exercise and Cardiovascular Health [DECIDE]-Salt Reduction Strategies for the Elderly in Nursing Homes in China [DECIDE-Salt]; NCT03290716).

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.

Hypotension prediction index for the prevention of hypotension during surgery and critical care: A narrative review.

Surgeons and anesthesia clinicians commonly face a hemodynamic disturbance known as intraoperative hypotension (IOH), which has been linked to more severe postoperative outcomes and increases mortality rates. Increased occurrence of IOH has been positively associated with mortality and incidence of myocardial infarction, stroke, and organ dysfunction hypertension. Hence, early detection and recognition of IOH is meaningful for perioperative management. Currently, when hypotension occurs, clinicians use vasopressor or fluid therapy to intervene as IOH develops but interventions should be taken before hypotension occurs; therefore, the Hypotension Prediction Index (HPI) method can be used to help clinicians further react to the IOH process. This literature review evaluates the HPI method, which can reliably predict hypotension several minutes before a hypotensive event and is beneficial for patients' outcomes.

Risk factors of more severe hypotension after spinal anesthesia for cesarean section.

BACKGROUND: The aim of this study was to examine the risk factors associated with the use of vasopressors to prevent hypotension that occurs after spinal anesthesia during cesarean section. Although the prophylactic use of vasopressors is already suggested as routine care in many parts of the world, the occurrence of spinal anesthesia-induced hypotension (SAIH) is still common in parturients. METHODS: This retrospective study included parturients receiving elective cesarean deliveries under spinal anesthesia from April 2016 to March 2020. Risk factors related to ephedrine dosage were analyzed using a hurdle model, and risk factors related to SAIH were further analyzed with logistic regression. RESULTS: Five risk factors, namely maternal body mass index (BMI, p < 0.001), baseline systolic blood pressure (SBP, p < 0.001), baseline heart rate (HR, p = 0.047), multiparity ( p = 0.003), and large fetal weight ( p = 0.005) were significantly associated with the requirement for ephedrine. Furthermore, a higher ephedrine dosage was significantly associated with maternal BMI ( p < 0.001), baseline SBP ( p < 0.001), baseline HR ( p < 0.001), multiparity ( p = 0.027), large fetal weight ( p = 0.030), maternal age ( p = 0.009), and twin pregnancies ( p < 0.001). Logistic regression analysis also showed that the same five risk factors-maternal BMI ( p = 0.030), baseline SBP ( p < 0.001), baseline HR ( p < 0.001), multiparity ( p < 0.001), and large fetal weight ( p < 0.001)-were significantly associated with SAIH, even in cases where vasopressors were administered. CONCLUSION: These findings can be useful for clinicians when deciding the dose of prophylactic ephedrine or phenylephrine to prevent SAIH.

Effect of using hypotension prediction index versus conventional goal-directed haemodynamic management to reduce intraoperative hypotension in non-cardiac surgery: A randomised controlled trial.

STUDY OBJECTIVE: It remains unclear whether it is the hypotension prediction index itself or goal-directed haemodynamic therapy that mitigates intraoperative hypotension. DESIGN: A single centre randomised controlled trial. SETTING: Sapporo Medical University Hospital. PATIENTS: A total of 64 adults patients undergoing major non-cardiac surgery under general anaesthesia. INTERVENTIONS: Patients were randomly assigned to either group receiving conventional goal-directed therapy (FloTrac group) or combination of the hypotension prediction index and conventional goal-directed therapy (HPI group). To investigate the independent utility of the index, the peak rates of arterial pressure and dynamic arterial elastance were not included in the treatment algorithm for the HPI group. MEASUREMENTS: The primary outcome was the time-weighted average of the areas under the threshold. Secondary outcomes were area under the threshold, the number of hypotension events, total duration of hypotension events, mean mean arterial pressure during the hypotension period, number of hypotension events with mean arterial pressure < 50 mmHg, amounts of fluids, blood products, blood loss, and urine output, frequency and amount of vasoactive agents, concentration of haemoglobin during the monitoring period, and 30-day mortality. MAIN RESULTS: The time-weighted average of the area below the threshold was lower in the HPI group than in the control group; 0.19 mmHg (interquartile range, 0.06-0.80 mmHg) vs. 0.66 mmHg (0.28-1.67 mmHg), with a median difference of -0.41 mmHg (95% confidence interval, -0.69 to -0.10 mmHg), p = 0.005. Norepinephrine was administered to 12 (40%) and 5 (17%) patients in the HPI and FloTrac groups, respectively (p = 0.045). No significant differences were observed in the volumes of fluid and blood products between the study groups. CONCLUSIONS: The current randomised controlled trial results suggest that using the hypotension prediction index independently lowered the cumulative amount of intraoperative hypotension during major non-cardiac surgery.

Comparative dose-response study on the infusion of norepinephrine combined with intravenous ondansetron versus placebo for preventing hypotension during spinal anesthesia for cesarean section: a randomised controlled trial.

BACKGROUND: Ondansetron has been reported to attenuate the incidence of spinal anaesthesia-induced hypotension (SAIH) and norepinephrine requirement during caesarean section. However, no quantitative study has evaluated the extent of this effect. This study aimed to determine the dose-response of prophylactic infusion of norepinephrine to prevent SAIH in parturients who received intravenous ondansetron or placebo before spinal anaesthesia for caesarean section. The median effective dose (ED 50 ) and 90% effective dose (ED 90 ) were compared to evaluate the effect of ondansetron versus placebo on the norepinephrine requirement. MATERIALS AND METHODS: One hundred fifty parturients undergoing caesarean section were randomized to receive either 0.1 mg/kg ondansetron (group O) or saline control (group C) 10 min before spinal anaesthesia. The parturients were randomly assigned to one of five different norepinephrine infusion groups: 0.02, 0.04, 0.06, 0.08 or 0.10 µg/kg/min. An effective infusion dose of norepinephrine was defined as non-occurrence of hypotension during the study period. The values for ED 50 and ED 90 of norepinephrine infusion were determined using probit regression. Differences between the two groups were evaluated by comparing the relative median potency with 95% CIs. RESULTS: The ED 50 values were 0.033 (95% CIs, 0.024-0.043) µg/kg/min in group C and 0.021 (95% CIs, 0.013-0.029) µg/kg/min in group O. The ED 90 values were 0.091 (95% CIs 0.068-0.147) µg/kg/min in group C and 0.059 (95% CIs 0.044-0.089) µg/kg/min in group O, respectively. The estimate of the relative median potency for norepinephrine in group C versus group O was 0.643 (95% CIs, 0.363-0.956). The incidence of side effects was comparable between groups. No significant difference in neonatal outcomes. CONCLUSION: Intravenous ondansetron 0.1 mg/kg before spinal anaesthesia significantly reduced the dose requirement of prophylactic norepinephrine infusion in parturients undergoing elective caesarean section. This finding is potentially useful for clinical practice and further research.

Effect of carotid corrected flow time combined with perioperative fluid therapy on preventing hypotension after general anesthesia induction in elderly patients: a prospective cohort study.

BACKGROUND: Hypotension often occurs following the induction of general anesthesia in elderly patients undergoing surgery and can lead to severe complications. This study assessed the effect of carotid corrected flow time (FTc) combined with perioperative fluid therapy on preventing hypotension after general anesthesia induction in elderly patients. MATERIALS AND METHODS: The prospective cohort study was divided into two parts. The first part (Part I) consisted of 112 elderly patients. Carotid FTc was measured using Color Doppler Ultrasound 5 min before anesthesia induction. Hypotension was defined as a decrease of greater than 30% in systolic blood pressure (SBP) or a decrease of greater than 20% in mean arterial pressure (MAP) from baseline, or an absolute SBP below 90 mmHg and MAP below 60 mmHg within 3 min after induction of general anesthesia. The predictive value of carotid FTc was determined using receiver operating characteristic (ROC) curve. The second part (Part II) consisted of 65 elderly patients. Based on the results in Part I, elderly patients with carotid FTc below the optimal cut-off value received perioperative fluid therapy at a volume of 8 ml/kg of balanced crystalloids (lactated Ringer's solution) in 30 min before induction. The effect of carotid FTc combined with perioperative fluid therapy was assessed by comparing observed incidence of hypotension after induction. RESULTS: The area under the ROC for carotid FTc to predict hypotension after induction was 0.876 [95% confidence interval (CI) 0.800-0.952, P <0.001]. The optimal cut-off value was 334.95 ms (sensitivity of 87.20%; specificity of 82.20%). The logistic regression analysis revealed that carotid FTc is an independent predictor for post-induction hypotension in elderly patients. The incidence of post-induction hypotension was significantly lower ( P <0.001) in patients with carotid FTc less than 334.95 ms who received perioperative fluid therapy (35.71%) compared to those who did not (92.31%). CONCLUSIONS: Carotid FTc combined with the perioperative fluid therapy could significantly reduce the incidence of hypotension after the induction of general anesthesia in elderly patients.

Intranasal dexmedetomidine as premedication for magnetic resonance imaging examinations in dogs with neurological disorders mitigates hypotension and hypothermia.

OBJECTIVE: This study aimed to evaluate the safety and feasibility of intranasal administration of dexmedetomidine as a premedication for preventing hypotension and hypothermia in canine patients undergoing MRI examinations. ANIMALS: Dogs undergoing MRI examinations for neurological disorders were enrolled in this study. The dogs were randomly assigned: 15 to the N-Dex group (without premedication) and 13 to the Dex group (125 µg/m2 of dexmedetomidine, intranasally, as a premedication). METHODS: During the examination, pulse rate, systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure were recorded every 5 minutes for the first 30 minutes. Body temperature was measured before and after the examination. Any adverse events during the procedure were documented. RESULTS: Significant changes in pulse rate during the examination were not distinguishable. Although blood pressure and body temperature decreased in both groups under anesthesia, dogs in the Dex group had a significantly smaller drop in blood pressure and body temperature and fewer hypotension events than those in the N-Dex group MRI examinations of 1 hour's duration. Two dogs in the Dex group exhibited bradycardia at 45 and 60 minutes of MRI examination, which resolved after receiving atipamezole. CLINICAL RELEVANCE: Our results indicate that intranasal administration of 125 µg/m2 of dexmedetomidine as premedication is safe and can potentially mitigate hypothermia and hypotension in dogs with neurological disorders during MRI examinations.