Cardiac output changes with phenylephrine and ephedrine infusions during spinal anesthesia for cesarean section: A randomized, double-blind trial

The AccuFlow sensor: a novel digital health tool to assess intrapartum blood loss at cesarean delivery

OBJECTIVES

During obstetric hemorrhage, peripheral vasoconstriction maintains heart rate and blood pressure until compensatory mechanisms are overwhelmed and patients deteriorate rapidly. Real-time perfusion measurements could quantify vasoconstriction, improving early recognition of hemorrhage and facilitating early intervention to reduce morbidity and mortality. The AccuFlow device makes rapid, non-invasive, quantitative measurements of perfusion, but has not been studied for hemorrhage detection or used in surgical settings. This study evaluated feasibility, tolerability, and preliminary efficacy of the AccuFlow for assessment of blood loss at cesarean delivery (CD).

METHODS

In this pilot study, sensors were applied to the wrist, forearm, bicep, and chest wall of 25 patients undergoing scheduled CD. Postoperatively, sensors were removed and patients rated the AccuFlow and the standard anesthesia monitoring equipment on a validated comfort rating scale for wearable computers (CRS). Blood loss was estimated by the surgical team (EBL) and calculated from change in hematocrit, weight, and height (CBL). CRS scores were compared via Wilcoxon signed ranks tests. Coefficients of correlation between sensor readings and CBL, and between EBL and CBL, were compared using Fisher's R-to-z transformation.

RESULTS

There were no safety events; no participants requested device removal. CRS ratings of the AccuFlow and the standard monitoring equipment were similar (7.2 vs. 8.8, p=0.25). Change in wrist perfusion from delivery to dressing placement was more strongly correlated with CBL than was EBL (R=-0.48 vs. R=0.087, p=0.03).

CONCLUSIONS

The AccuFlow sensor is well-tolerated and shows promise in detecting intrapartum hemorrhage, though larger studies are needed.

Investigation of the Optimum Baseline Blood Pressure for Spinal Anesthesia to Guide Vasopressor Management for Elective Cesarean Delivery: A Case-Control Design

BACKGROUND

Current guidelines recommend prophylactic vasopressor administration during spinal anesthesia for cesarean delivery to maintain intraoperative blood pressure above 90% of the baseline value. We sought to determine the optimum baseline mean arterial pressure (MAP) reading to guide the management of spinal hypotension.

METHODS

We performed a secondary analysis of data collected from normotensive patients presenting for elective cesarean delivery in a tertiary care institution from October 2018 to August 2020. We compared the magnitude of hypotension in patients who reported nausea versus those who did not, using a case-control design. Baseline MAPs at last office visit, morning of surgery, or operating room (pre-spinal) were determined. We calculated the duration and degree of hypotension using the area under the curve (AUC) when the MAP of the respective patient was below 90% of each baseline.

RESULTS

The patients who experienced nausea (n=45) had longer and more profound periods of hypotension than those who did not develop nausea (n=240). A comparison of AUC using MAP baseline at the last office visit or on the morning of surgery showed a statistically significant between-group difference, P=0.02, and P=0.005, respectively, and no significant between-group difference when 90% of the MAP baseline in the operating room was used.

CONCLUSIONS

Patients had the highest preoperative MAP in the operating room and the AUC was similar for those with and without nausea when the pre-spinal MAP baseline was used. Therefore, maintaining higher intraoperative blood pressure using individual pre-spinal MAP as baseline should reduce intraoperative maternal nausea.

Manually Controlled, Continuous Infusion of Phenylephrine or Norepinephrine for Maintenance of Blood Pressure and Cardiac Output During Spinal Anesthesia for Cesarean Delivery: A Double-Blinded Randomized Study

BACKGROUND

To counteract the vasoplegia induced by spinal anesthesia (SA) and maintain blood pressure (BP) during cesarean delivery, phenylephrine is currently recommended, but norepinephrine might offer superior preservation of cardiac output. We aimed to compare the hemodynamic effects of phenylephrine and norepinephrine administered by manually adjusted continuous infusion during elective cesarean delivery.

METHODS

In this pragmatic, parallel-group, double-blind randomized controlled trial, 124 parturients scheduled for elective cesarean delivery under SA in a tertiary maternity in France, between February 2019 and December 2020, were randomized to receive norepinephrine at a starting rate of 0.05 μg·kg -1 ·min -1 (n = 62) or phenylephrine at a starting rate of 0.5 μg·kg -1 ·min -1 (n = 62). In both groups, the vasopressor infusion rate was then manually adjusted to maintain maternal systolic BP above 90% of the baseline value. The primary outcome, the change in cardiac index (CI) measured by thoracic bioreactance from SA to umbilical cord clamping, was analyzed through repeated measures analysis of variance and post hoc t tests. Secondary outcomes included maternal BP and neonatal outcomes.

RESULTS

In the norepinephrine group, cardiac index was maintained between 90% and 100% of baseline from SA to umbilical cord clamping, whereas it was maintained at significantly lower values (81%-88%) in the phenylephrine group ( P = .001). The percentage of elapsed time with a mean maternal BP <65 mm Hg and with systolic BP <80% of the baseline value was higher in the phenylephrine group: 2.9% (7.3) vs 0.5% (1.8) (absolute risk difference [ARD], -2.4%; 95% confidence interval, -4.4 to -0.5; P = .012) and 8.5% (16.6) vs 2.3% (5.2) (ARD, -6.2%; 95% confidence interval, -10.6 to -1.8; P = .006). Excluding parturients with gestational diabetes, severe neonatal hypoglycemia was more common in the phenylephrine group at 19.6% (9/46) vs 4.1% (2/49) ( P = .02). The other neonatal outcomes did not differ significantly between the groups.

CONCLUSIONS

When administered by manually adjusted infusion during SA for cesarean delivery, norepinephrine was associated with a higher CI; both infusions were effective for maintaining BP.

Blood vessel assessment using computed tomography : Effects of ephedrine on uterine artery

Background: Ephedrine increased blood pressure due to the contractile properties of resistance vessels. Excessive contraction of the uterine arteries might cause fetal distress. This study was to determine the diameter of the uterine artery of female New Zealand rabbits after the administration of different doses of ephedrine using CT.

Methods: Thirty-two rabbits were randomly divided into a control group (Group C), low dosage group (Group L), medium dosage group (Group M) and high dosage group (Group H). Normal saline and doses corresponding to the human dose of 7.5, 15 and 30 mg of ephedrine were injected respectively. The marginal ear and uterine artery diameters were measured 5, 10, 15, 30, and 45 min after injection using CT, and the hemodynamic changes were recorded.

Results: The increase in mean arterial pressure in group M (p = 0.009), and H (p = 0.013) was higher than that in group C. Compared with group C, substantial contraction of the marginal ear artery was observed at the three doses of ephedrine. There were no differences in the uterine artery diameter among groups L, M and C, However, in Group H, a significant contraction of the uterine artery compared with the other groups (p < 0.001) was observed.

Discussion: CT can be used to evaluate the effects of drugs on organs and blood vessels. Ephedrine can not only constrict the peripheral blood vessels but also do not affect the uterine artery at a dose of 15 mg or less. However, the dose should not exceed 30 mg, which may cause severe uterine artery depression.

A Prospective Randomized Study Comparing the Bolus Doses of Norepinephrine and Phenylephrine for the Treatment of Spinal Induced Hypotension in Cesarean Section

Background: Spinal anesthetic-induced hypotension is the most worrisome complication for patients undergoing cesarean section under spinal anesthesia. The present study compares norepinephrine and phenylephrine bolus for the treatment of hypotension during spinal anesthesia for cesarean section.

Methods: One hundred twenty- six women aged between 22 and 40 years with singleton pregnancy classified to the American Society of Anesthesiologists (ASA) physical class I and II posted for elective cesarean section under spinal anesthesia were randomly divided into two groups of 63 each. Group I patients received phenylephrine 50 mcg (microgram) as an intravenous bolus, and Group II received 4 mcg of norepinephrine as an intravenous bolus to treat spinal hypotension.

Results: On comparing the demographic data of the patients in terms of age, weight, height, ASA Grade, level of block and surgery time no significant differences were found between the groups. Similarly, the fetal parameters were found to be not significantly different between the groups. However, the number of bolus doses of vasopressors required for the treatment of spinal-induced hypotension was significantly reduced in Group II (p=0.02). The frequency of bradycardia was found to be higher in patients who were given phenylephrine as compared to patients administered noradrenaline boluses (p=0.03). Five (7.93%) patients had shivering in Group I, while similar episodes were observed in 10 (15.87%) patients (p=0.05). Moreover, no significant difference was observed in comparing the heart rate and mean arterial pressure between the groups.

Conclusion: Intermittent boluses of norepinephrine are found to be effective in the management of spinal‑induced hypotension during caesarean section.

Comparison of Prophylactic Norepinephrine and Phenylephrine Infusions During Spinal Anaesthesia for Primary Caesarean Delivery in Twin Pregnancies: A Randomized Double-Blinded Clinical Study

Background

Norepinephrine has been associated with improved heart rate (HR) and cardiac output (CO) compared to phenylephrine as a treatment for post-spinal hypotension during caesarean delivery (CD) in singleton pregnancies. Our current study compared the effects of norepinephrine and phenylephrine in maintaining maternal hemodynamics after spinal anaesthesia in twin pregnancies during elective CD.

Methods

This was a double-blinded, randomized, controlled study. From December 2017 to December 2018, 62 women with healthy twin term pregnancies undergoing elective CD under spinal anaesthesia were studied. Following spinal induction, either norepinephrine (6 μg/mL) or phenylepinephrine (75 μg/mL) was infused at 60 mL/h to maintain systolic blood pressure (SBP) near baseline until delivery. HR, SBP, systemic vascular resistance (SVR), and CO were collected using anaesthesia monitors and continuous-pulse waveform analysis. The primary outcome was maternal CO. Other parameters of maternal hemodynamics, umbilical cord blood gases, and adverse events were also compared.

Results

Hemodynamic variables (CO, SBP, HR, and SVR) between spinal anaesthesia induction to skin incision were similar between the two groups (P = 0.889, 0.057, 0.977, and 0.416, respectively). The incidence of bradycardia was significantly higher in the phenylephrine group (69%) than in the norepinephrine group (24.2%, P<0.001). Maternal nausea and vomiting, hypotension, reactive hypertension, and neonatal outcomes did not differ between the groups.

Conclusion

When administered as a prophylactic fixed-rate infusion, phenylephrine and norepinephrine are both capable of maintaining maternal blood pressure following spinal anaesthesia in twin pregnancies. There were no differences in the maternal hemodynamics or foetal outcomes between women receiving norepinephrine and phenylephrine.

Previous Presentations

Presented at the 51st Society for Obstetric Anesthesia and Perinatology Annual Meeting, Phoenix, Arizona, May 1–5, 2019.

Clinical Trial Number and Registry

No. ChiCTR-IOR-17013358.

Phenylephrine-Induced Cardiovascular Changes in the Anesthetized Mouse: An Integrated Assessment of in vivo Hemodynamics Under Conditions of Controlled Heart Rate

Objective

Investigating the cardiovascular system is challenging due to its complex regulation by humoral and neuronal factors. Despite this complexity, many existing research methods are limited to the assessment of a few parameters leading to an incomplete characterization of cardiovascular function. Thus, we aim to establish a murine in vivo model for integrated assessment of the cardiovascular system under conditions of controlled heart rate. Utilizing this model, we assessed blood pressure, cardiac output, stroke volume, total peripheral resistance, and electrocardiogram (ECG).

Hypothesis

We hypothesize that (i) our in vivo model can be utilized to investigate cardiac and vascular responses to pharmacological intervention with the α₁-agonist phenylephrine, and (ii) we can study cardiovascular function during artificial pacing of the heart, modulating cardiac function without a direct vascular effect.

Methods

We included 12 mice that were randomly assigned to either vehicle or phenylephrine intervention through intraperitoneal administration. Mice were anesthetized with isoflurane and intubated endotracheally for mechanical ventilation. We measured blood pressure via a solid-state catheter in the aortic arch, blood flow via a probe on the ascending aorta, and ECG from needle electrodes on the extremities. Right atrium was electrically paced at a frequency ranging from 10 to 11.3 Hz before and after either vehicle or phenylephrine administration.

Results

Phenylephrine significantly increased blood pressure, stroke volume, and total peripheral resistance compared to the vehicle group. Moreover, heart rate was significantly decreased following phenylephrine administration. Pacing significantly decreased stroke volume and cardiac output both prior to and after drug administration. However, phenylephrine-induced changes in blood pressure and total peripheral resistance were maintained with increasing pacing frequencies compared to the vehicle group. Total peripheral resistance was not significantly altered with increasing pacing frequencies suggesting that the effect of phenylephrine is primarily of vascular origin.

Conclusion

In conclusion, this in vivo murine model is capable of distinguishing between changes in peripheral vascular and cardiac functions. This study underlines the primary effect of phenylephrine on vascular function with secondary changes to cardiac function. Hence, this in vivo model is useful for the integrated assessment of the cardiovascular system.

Neonatal outcomes following prophylactic administration of phenylephrine or noradrenaline in women undergoing scheduled caesarean delivery: A randomised clinical trial

BACKGROUND

There is limited evidence to support the use of noradrenaline over phenylephrine during elective caesarean section with regards to its impact on foetal acidosis. Concerns regarding a deleterious effect of noradrenaline on foetal blood gas analysis because of its β-mimetic activity cannot currently be ruled out by data from randomised controlled trials.

OBJECTIVE

We hypothesised that noradrenaline would be associated with higher umbilical artery base excess values and less foetal acidosis compared with phenylephrine. This study aimed to observe the effect of prophylactic infusions of phenylephrine or noradrenaline in low-risk elective caesarean delivery on umbilical artery blood gas analysis.

DESIGN

A prospective, randomised, double-blind trial.

SETTING

Labour room operating theatre of tertiary care hospital in Northern India from April 2020 to November 2020.

PATIENTS

Full-term, nonlabouring pregnant women, scheduled for elective caesarean delivery under spinal anaesthesia.

INTERVENTION

Equipotent prophylactic infusions of either phenylephrine 100 μg min-1 or noradrenaline 5 μg min-1 were administered to maintain maternal SBP between 90 and 110% of baseline using a predefined algorithm.

MAIN OUTCOME MEASURE

The primary outcome was umbilical artery base excess in noradrenaline versus the phenylephrine group. The incidence of foetal acidosis defined as umbilical artery base excess less than -6 mmol l-1 was also assessed for noradrenaline versus phenylephrine.

RESULTS

Median [IQR] umbilical artery base excess was significantly higher in the noradrenaline group: -5.4 [-6.6 to -4.03] versus -6.95 [-9.02 to -4.53] in the phenylephrine group (P = 0.014). No significant difference in the incidence of foetal acidosis was observed between noradrenaline and phenylephrine groups: 36 versus 54% (P 0.07); difference 18% (95% CI, -1.4 to 35.6%).

CONCLUSION

Prophylactic noradrenaline 5 μg min-1 infusion resulted in higher base excess values compared with phenylephrine 100 μg min-1 infusion. A comparable incidence of foetal acidosis was observed in women receiving either noradrenaline or phenylephrine. Maternal bradycardia was more pronounced with phenylephrine while targeting blood pressure goals.

CTRI

CTRI/2020/03/023986.

Continuous transthoracic echocardiographic monitoring for changes in maternal cardiac hemodynamics during cesarean section under combined epidural-spinal anesthesia: a prospective, observational study

The change in maternal hemodynamics during cesarean section has not been well studied. Continuous transthoracic echocardiography can monitor cardiac function continuously. This study aimed to evaluate the effectiveness of maternal hemodynamic parameters monitoring during cesarean section using continuous transthoracic echocardiography. In this prospective, observational study, women with an uncomplicated singleton pregnancy scheduled for elective cesarean section at term under combined spinal-epidural anesthesia were enrolled. Maternal hemodynamic parameters were assessed by continuous transthoracic echocardiography at 11 pre-set time points. The image quality of continuous transthoracic echocardiography was evaluated before measurement was performed. Totally, one hundred parturients were recruited, and transthoracic echocardiography images with sufficient quality for further analysis were obtained in 72 women. Following anesthesia, maternal heart rate decreased by 11.18% and cardiac output decreased by 7.82%, but stroke volume remained stable. After delivery of the neonate and placenta, stroke volume and cardiac output increased by 21.09% and 22.33%, respectively. End-diastolic volume also increased significantly after delivery of the neonate, but end-systolic volume was unchanged. Following delivery of the neonate, fractional shortening increased till the end of the cesarean section while total peripheral resistance decreased significantly. In conclusion, continuous transthoracic echocardiographic monitoring revealed that there were significant changes in hemodynamic parameters during cesarean section after delivery of the newborn and placenta, which warranted further investigation.

Blood pressure and cardiac output during caesarean delivery under spinal anaesthesia: a prospective cohort study

OBJECTIVES

We have previously established a method to measure transfer of nutrients between mother, placenta and fetus in vivo. The method includes measurements of maternal and fetal blood flow by Doppler ultrasound prior to spinal anaesthesia. Spinal anaesthesia affects maternal blood pressure and cardiac output. We aimed to determine the effect of spinal anaesthesia in mothers undergoing an elective caesarean section on blood pressure, heart rate and cardiac output, and whether cardiac output levels were comparable before induction of spinal anaesthesia and before delivery.

DESIGN

Prospective cohort study.

SETTING

Tertiary hospital in Norway.

PARTICIPANTS

76 healthy women with uneventful pregnancies undergoing an elective caesarean section.

INTERVENTIONS

We induced spinal anaesthesia with a standard prevention of hypotension including intravenous fluid coloading and phenylephrine infusion.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome measure was maternal cardiac output, and secondary outcome measures were invasive systolic blood pressure and heart rate. We measured heart rate and blood pressure by continuous invasive monitoring with a cannula in the radial artery. Cardiac output was estimated based on continuous arterial waveform. We compared maternal parameters 30 s before induction of spinal anaesthesia to 30 s before delivery.

RESULTS

Median age at delivery was 34.5 (range 21-43) years and 17 of 76 women were nulliparous. The most prevalent indications were previous caesarean section and maternal request. Among 76 included women, 71 had sufficient data for analysis of endpoints. Median cardiac output was 6.51 (IQR (5.56-7.54) L/min before spinal anaesthesia and 6.40 (5.83-7.56) L/min before delivery (p=0.40)). Median invasive systolic blood pressure increased from 128.5 (120.1-142.7) mm Hg to 134.1 (124.0-146.6) mm Hg (p=0.014), and mean heart rate decreased from 86.0 (SD 13.9) to 75.2 (14.2) (p<0.001).

CONCLUSIONS

Maternal cardiac output at the time of caesarean delivery is comparable to levels before induction of spinal anaesthesia.

TRIAL REGISTRATION NUMBER

NCT00977769.

Minimally Invasive Hemodynamic Assessment during Obstetric Hysterectomy for Invasive Placentation with Epidural Anesthesia

Background

The present study aimed to describe the evolution of hemodynamic parameters over time of patients with invasive placentation during their third trimester who were delivered via cesarean section and subsequently underwent obstetric hysterectomy under epidural anesthesia.

Methods

A prospective, descriptive, longitudinal, 11-month cohort study of 43 patients aged between 18 and 37 years who presented with invasive placentation. Minimal invasive monitoring was placed before the administration of epidural anesthesia for hemodynamic parameter tracking during the cesarean section. After delivery, the patients underwent an obstetric hysterectomy. Blood loss, hemodynamic parameters, and coagulation were managed via goal-directed therapy. Parameters were compared via repeated measures ANOVA and effect size estimation (Cohen's d).

Results

The mean age of the patients was 29.2 ± 3.4 years and was moderately overweight. They had minor cardiac index variance (P=NS, no significance), vascular systemic resistance index (NS), heart rate (P=NS), and median arterial pressure (P=NS). Differences were observed in the stroke volume index (P=0.015) due to moderately higher values (d = 0.3, P=0.016) in the middle of the surgery. Patients had lower cardiac index (d = -0.36, NS) and cardiac workload requirements (d = -0.29, P=0.034) toward the completion of surgery.

Conclusion

Patients who are in their third trimester and who subsequently underwent obstetric hysterectomy under epidural anesthesia had modest surgical hemodynamic variance and reduced cardiac workload requirements toward the end of the surgery.

Voltammetric Analysis of Ephedrine in Pharmaceutical Dosage Forms and Urine Using poly(Nile Blue A) Modified Glassy Carbon Electrode

OBJECTIVE

The electrochemical analysis of ephedrine which is a sympathometric drug has been studied using poly(Nile blue A) modified glassy carbon electrodes, cyclic voltammetry, differential pulse voltammetry and square wave voltammetry.

METHODS

The modified electrodes were prepared by potential cycling electropolymerization of Nile blue A in 0.1 M phosphate buffer solution at pH 6.0. The redox behavior of ephedrine was investigated in different buffer solutions at pH values between 5.5 and 9.0.

RESULTS

Scan rate studies showed that the electron transfer reaction of ephedrine was diffusion controlled. A linear response was obtained between the peak current and the ephedrine concentration in the range of 0.6 to 100 μM with a limit of detection of 2.91×10^-3 μM for differential pulse voltammetry in Britton-Robinson buffer solution at pH 9.0. The linearity range of ephedrine in human urine was between 1.0 and 100 μM with a detection limit of 8.16 nM.

CONCLUSION

The recovery studies in both pharmaceutical dosage forms and urine showed that the proposed method ensured good selectivity, precision and accuracy without any interference from inactive excipients.

Hemodynamic characteristics in preeclampsia women during cesarean delivery after spinal anesthesia with ropivacaine

BACKGROUND

Very few studies have been published on the hemodynamic changes associated with spinal anesthesia induced with ropivacaine during cesarean deliveries in preeclamptic women.

AIM

To record and analyze hemodynamic data in women with preeclampsia undergoing cesarean delivery after spinal anesthesia induced with ropivacaine.

METHODS

Ten eligible women with preeclampsia were enrolled in this prospective observational study. Spinal anesthesia was performed with 2.4 mL of 0.5% ropivacaine. Hemodynamic changes were then analyzed at multiple time points. The hemodynamic responses to vasopressor interventions and uterotonic agents, as well as maternal and neonatal outcomes were also recorded.

RESULTS

Stable hemodynamic trends were observed in this study. Cardiac output (CO) and stroke volume increased mildly during surgery. In contrast, mean arterial pressure and systemic vascular resistance showed a moderate decrease from induction until the end of surgery. Central venous pressure dramatically increased after delivery. Oxytocin administration was associated with the most significant hemodynamic fluctuations during surgery, namely, an increase in CO and heart rate. Phenylephrine intervention was only required in three patients, and caused an increase in mean arterial pressure and systemic vascular resistance along with a decrease in heart rate, stroke volume, and CO. No maternal and neonatal complications were observed during this study, except transient episodes of hypotension.

CONCLUSION

Spinal anesthesia for caesarian delivery with ropivacaine in women with preeclampsia is linked to modest hemodynamic changes of no clinical significance in this study. Careful cardiovascular monitoring is still recommended, particularly after the delivery of the fetus or the use of oxytocin.

Comparison of norepinephrine and phenylephrine boluses for the treatment of hypotension during spinal anaesthesia for caesarean section - A randomised controlled trial

Background and Aims:

Hypotension following spinal anaesthesia for caesarean section is common in spite of adequate fluid loading. Phenylephrine is the recommended drug to treat spinal hypotension during caesarean section. Recently, norepinephrine boluses are being suggested as an alternative to phenylephrine boluses. The aim of our study was to compare the effectiveness of bolus doses of norepinephrine with phenylephrine to treat spinal hypotension during caesarean section.

Methods:

Fifty patients undergoing elective caesarean section under spinal anaesthesia were randomly assigned into two groups. Group P patients received phenylephrine 50 μg as an intravenous bolus and group N received 4 μg of norepinephrine as intravenous bolus to treat spinal hypotension. The primary objective of our study was to compare the number of bolus doses of norepinephrine or phenylephrine required to treat spinal hypotension. The secondary objectives were to compare the incidence of bradycardia, hypertension, nausea and vomiting in mother and foetal outcomes.

Results:

The number of boluses of vasopressors required to treat hypotension was significantly lower in group N (1.40 ± 0.577 vs. 2.28 ± 1.061, P = 0.001). The frequency of bradycardia was high in group P, but this difference was not statistically significant (4%vs. 20%, P = 0.192). Maternal complications such as nausea and vomiting and shivering were comparable between the groups. The foetal parameters were also comparable between the two groups.

Conclusion:

Intermittent boluses of norepinephrine are effective in the management of spinal-induced hypotension during caesarean section. The neonatal outcomes were similar in both the groups. Norepinephrine boluses can be considered as an alternative to phenylephrine boluses.

The influence of the infusion of ephedrine and phenylephrine on the hemodynamic stability after subarachnoid anesthesia in senior adults - a controlled randomized trial

Background

We studied the influence of ephedrine or phenylephrine infusion administered immediately after spinal anesthesia (SA) on hemodynamics in elderly orthopedic patients.

Methods

A prospective, randomized, double-blind, placebo-controlled study.

After a subarachnoid injection of 15 mg of levobupivacaine, the participants received an infusion of either ephedrine 20 mg (E group), phenylephrine 250 mcg (P group) or saline (C group) within 30 min. We measured blood pressure, cardiac index (CI) and heart rate (HR) from 15 min before to 30 min after SA.

Results

Seventy patients were included in the final analysis. At the end of measurements, mean arterial pressure (MAP) decreased significantly after SA in comparison to the baseline value in the C group but was maintained in the P and E group, with no significant differences between the groups. CI decreased after SA in the C group, was maintained in the P group, and increased significantly in the E group with significant differences between the C and E group (p = 0.049) also between the P and E (p = 0.01) group at the end of measurements. HR decreased significantly after SA in the C and P group but was maintained in the E group, with significant differences between the P and E group (p = 0.033) at the end of measurements.

Conclusions

Hemodynamic changes after SA in elderly orthopedic patients can be prevented by an immediate infusion of phenylephrine or ephedrine. In addition to maintaining blood pressure, the ephedrine infusion also maintains HR and increases CI after SA.

Trial registration

ISRCTN registry with registration number ISRCTN44377602, retrospectively registered on 15 June 2017.

Prevention of hypotension after spinal anaesthesia for caesarean section: a systematic review and network meta-analysis of randomised controlled trials

Spinal anaesthesia for caesarean section commonly causes maternal hypotension. This systematic review and network meta-analysis compared methods to prevent hypotension in women receiving spinal anaesthesia for caesarean section. We selected randomised controlled trials that compared an intervention to prevent hypotension with another intervention or inactive control by searching MEDLINE and Embase, Web of Science to December 2018. There was no language restriction. Two reviewers extracted data on trial characteristics, methods and outcomes. We assessed risk of bias for individual trials (Cochrane tool) and quality of evidence (GRADE checklist). We assessed 109 trials (8561 women) and 12 different methods that resulted in 30 direct comparisons. Methods ranked by OR (95%CI) from most effective to least effective were: metaraminol 0.11 (0.04-0.26); norepinephrine 0.13 (0.06-0.28); phenylephrine 0.18 (0.11-0.29); leg compression 0.25 (0.14-0.43); ephedrine 0.28 (0.18-0.43); colloid given before induction of anaesthesia 0.38 (0.24-0.61); angiotensin 2, 0.12 (0.02-0.75); colloid given after induction of anaesthesia 0.52 (0.30-0.90); mephentermine 0.09 (0.01-1.30); crystalloid given after induction of anaesthesia 0.78 (0.46-1.31); and crystalloid given before induction of anaesthesia 1.16 (0.76-1.79). Phenylephrine caused maternal bradycardia compared with control, OR (95%CI) 0.23 (0.07-0.79). Ephedrine lowered umbilical artery pH more than phenylephrine, standardised mean difference (95%CI) 0.78 (0.47-1.49). We conclude that vasopressors should be given to healthy women to prevent hypotension during caesarean section with spinal anaesthesia.

Co-induction with a vasopressor "chaser" to mitigate propofol-induced hypotension when intubating critically ill/frail patients-A questionable practice

Prophylactic administration of a vasopressor to mitigate the hypotensive effect of propofol (and/or other co-induction agents) during sedation/anesthesia immediately prior to tracheal intubation in frail patients in the intensive care unit and emergency and operating rooms appears to be not an uncommon practice. We submit that this practice is unnecessary and potentially harmful. Despite restoring the blood pressure, phenylephrine, for instance, may have an additive or synergistic effect with propofol in reducing the cardiac output and, ultimately, organ perfusion. Airway instrumentation often leads to sympathetic activation and hypertension (thereby increasing myocardial oxygen consumption) which may be exacerbated by an arbitrary prophylactic dose of phenylephrine. Finally, in spite of the well-recognized need to reduce dosages of propofol in frail patients, excessive doses are commonly given, leading to hypotension. We herein discuss each of these points and suggest alternative techniques to promote a stable induction in frail patients.

Granisetron reduces the need for uterotonics but not sympathomimetics during cesarean delivery

OBJECTIVE

To assess the effect of a 5-hydroxytryptamine-3 receptor antagonist (granisetron) on the use of sympathomimetic (cafedrine/theodrenaline) and uterotonic (oxytocin) agents after spinal anesthesia during cesarean delivery.

METHODS

A retrospective observational analysis was conducted using intraoperative records (n=240) created at a single hospital in Germany between November 1, 2016, and July 31, 2017. The granisetron group (n=120) had received 3 mg of granisetron immediately before induction of spinal anesthesia. The control group (n=120) had not received granisetron. The primary endpoints were the intraoperative requirements for sympathomimetic and uterotonic agents. The secondary endpoints were parameters of intraprocedural maternal hemodynamic and clinical states.

RESULTS

More patients in the granisetron group than in the control group received intraoperative cafedrine/theodrenaline (P=0.045), with the cumulative intraoperative dosage also increased in the granisetron group (P=0.016). By contrast, the cumulative intraoperative dose of oxytocin was lower in the granisetron group than in the control group (P<0.001). Decreases in heart rate and mean arterial blood pressure were lower in the granisetron group versus the control group (P=0.015 and P=0.002, respectively).

CONCLUSION

Treatment with granisetron immediately before cesarean delivery did not reduce the perioperative requirement for sympathomimetics but did reduce the need for uterotonics. REGISTERED AT CLINICALTRIALS.GOV (NCT03318536).

Recommendations for the use of ECT in pregnancy: literature review and proposed clinical protocol

Psychiatric disorders are common in pregnancy, affecting 15-29% of pregnant women. Untreated depression has negative health consequences for mother and fetus. Electroconvulsive therapy (ECT) is an effective option for the treatment of severe depression, high suicide risk, catatonia, medication-resistant illness, psychotic agitation, severe physical decline, and other life-threatening conditions. To our knowledge, however, there is no literature that consolidates all the evidence on maternal and fetal risks associated with untreated depression, medications, and ECT then translating it into one cohesive protocol that could serve as a management guide and a source of reassurance to health-care providers involved in such practice. Hoping to facilitate ECT access to perinatal patients, the authors combined their multidisciplinary clinical experience (in perinatal psychiatry, neuropsychiatry and neuromodulation, and anesthesiology) at three different centers in the USA (Brigham and Women's Hospital/Harvard Medical School, The University of Chicago, and Brown University) with a careful and critical literature review and propose guidelines for the administration of ECT in pregnancy. A comprehensive review of the relevant literature regarding both ECT and psychotropic medications in pregnancy was performed, including meta-analyses of randomized controlled trials published in general medicine, anesthesiology, psychiatry, and obstetrics journals and guidelines. The indication and appropriateness of ECT in pregnancy must be carefully weighed against the risks of untreated maternal illness and those of alternative treatment options. The safety of ECT in pregnancy has been documented over the last 50 years. The adverse effects in pregnancy are similar to the risks of ECT in any individual. The most common risk to the mother is premature contractions and preterm labor, which occur infrequently and are not clearly caused by ECT. The rates of miscarriages were not significantly different from that of the general population. There have been no associations of ECT with congenital anomalies, either morphologic or behavioral, and no neurocognitive disturbances in the child. ECT is a reasonably safe and effective treatment alternative for management of many psychiatric disorders in pregnant patients. The authors provide recommendations for treatment modifications in pregnancy-based physiologic changes that occur during that period and consolidate them into a protocol that can assist clinicians in improving access and safety of ECT for pregnant patients.

Phenylephrine vs ephedrine in cesarean delivery under spinal anesthesia: A systematic literature review and meta-analysis

BACKGROUND

In the past 20 years, many studies compared phenylephrine with ephedrine to prevent or treat hypotension in elective or emergency cesarean delivery and parturients with pre-eclampsia. A meta-analysis of the abovementioned trials is needed.

METHODS

Several databases (PubMed, Embase, Web of Science and Cochrane Library) were searched from inception to April 2018 for trials comparing phenylephrine with ephedrine in cesarean delivery. The primary outcome is the incidence of maternal hypotension.

RESULTS

Thirty-six trials (2439 patients) with elective cesarean delivery, three trials (400 patients) with emergency cesarean delivery and three trials (192 patients) with parturients with pre-eclampsia were included and analyzed. The incidence of hypotension did not differ in the elective surgery group (relative risk 0.83, 95% CI 0.66 to 1.05), emergency surgery group (relative risk 1.02, 95% CI 0.87 to 1.19) and pre-eclamptic parturients group (relative risk 0.93, 95% CI 0.63 to 1.37). The phenylephrine group had a higher incidence of bradycardia and lower incidences of tachycardia and nausea or vomiting in all three patient groups. The phenylephrine group also had lower fetal acidosis rate, higher umbilical artery and vein pH values and less base excess in the elective surgery. The abovementioned outcomes were similar in the emergency surgery group and the pre-eclampsia group. Publication bias for hypotension was detected. However, the trim and fill method demonstrated that the publication bias had little impact on hypotension. Trial sequential analysis of hypotension in elective surgery showed that this meta-analysis lacked a sufficient cumulative sample size and that further studies should be included.

CONCLUSION

Phenylephrine and ephedrine were both effective in maintaining hemodynamic balance. Newborns benefited more from phenylephrine in elective cesarean delivery, but not in emergency cesarean delivery or in parturients with pre-eclampsia. More trials should be included to achieve more conclusive results.

A global perspective on vasoactive agents in shock

PURPOSE

We set out to summarize the current knowledge on vasoactive drugs and their use in the management of shock to inform physicians' practices.

METHODS

This is a narrative review by a multidisciplinary, multinational-from six continents-panel of experts including physicians, a pharmacist, trialists, and scientists.

RESULTS AND CONCLUSIONS

Vasoactive drugs are an essential part of shock management. Catecholamines are the most commonly used vasoactive agents in the intensive care unit, and among them norepinephrine is the first-line therapy in most clinical conditions. Inotropes are indicated when myocardial function is depressed and dobutamine remains the first-line therapy. Vasoactive drugs have a narrow therapeutic spectrum and expose the patients to potentially lethal complications. Thus, these agents require precise therapeutic targets, close monitoring with titration to the minimal efficacious dose and should be weaned as promptly as possible. Moreover, the use of vasoactive drugs in shock requires an individualized approach. Vasopressin and possibly angiotensin II may be useful owing to their norepinephrine-sparing effects.

Perioperative noninvasive cardiac output monitoring in parturients undergoing cesarean delivery with spinal anesthesia and prophylactic phenylephrine drip: a prospective observational cohort study

Introduction: Spinal anesthesia for cesarean delivery is associated with high incidence of hypotension and is most often prevented by a prophylactic phenylephrine infusion (PPI). In this study, we aimed to identify maternal hemodynamic changes both intraoperatively and postoperatively with the use of the NICaS noninvasive cardiac output monitor in healthy singleton parturients undergoing cesarean delivery (CD) with spinal anesthesia and PPI. Methods: Healthy term women undergoing spinal anesthesia for singleton CD were enrolled. The following data were collected - cardiac output (CO), mean arterial pressure (MAP), stroke volume (SV), and total peripheral resistance (TPR). Measurements were measured at five time points: (1) before arrival in OR, (2) after spinal anesthesia with pi, (3) after delivery of baby and beginning of oxytocin infusion, (4) in post anesthesia care room (5) 24 hours postoperatively, and (6) 48 hours postoperatively. All parturients received standardized spinal solution consisting of 12 mg hyperbaric, 20 µg fentanyl, and 100-µg preservative-free morphine. PPI was titrated to preserve blood pressure to 20% of baseline and stopped at the end of surgery. Oxytocin was administered as a continuous infusion (20-units/1000 cc Ringer lactate) at a rate of 100 cc/h. Results: One hundred thirty-seven women completed the study. Average age was 34.9 ± 5.7 and average BMI was 30.1 ± 5.1. One hour after delivery in the post anesthesia care unit (PACU), there were significant decreases in stroke volume, heart rate, blood pressure, and CO with a concomitant increase in TPR. Within 48 hours the TPR decreased, and CO and stroke volume increased. Conclusions: Significant hemodynamic changes were documented at all time points both intraoperatively and postoperatively with the most significant changes occurring 1 hour postoperatively. Further studies need to be performed to discover hemodynamic changes of spinal anesthesia and PPI in different parturient populations.