Equivalent dose of ephedrine and phenylephrine in the prevention of post-spinal hypotension in Caesarean section

Hypotension duration and vasopressor requirements following intrathecal oxytocin for Total hip arthroplasty: Secondary analysis of a randomized controlled trial

INTRODUCTION

A recent publication investigating intrathecal oxytocin, 100 μg, administered immediately prior to a spinal anesthetic in patients undergoing primary total hip arthroplasty surgery demonstrated a reduction in disability for 3-weeks, increased walking distance at 8-weeks, and earlier opioid cessation. This secondary analysis study was undertaken to assess the acute cardiovascular safety and analgesic efficacy of intrathecal oxytocin in this study population.

METHODS

90 patients were included in the analysis (44 randomized to spinal oxytocin and 46 to placebo [saline]). Data collected prospectively during the previously published study were supplemented with additional retrospectively collected data. The primary outcomes were comparisons of the duration of hypotension (minutes with mean arterial pressure < 65 mmHg) and cumulative vasopressor requirements during the initial 60 min following spinal placement. Secondary outcomes included hypotension durations and vasopressor requirements at later time points, perioperative fluid administration, physical therapy metrics, time to first opioid administration, cumulative opioid consumption through 24 h, and verbal pain scores through 24 h.

RESULTS

The duration of hypotension during the first 60 min following spinal placement did not differ between intrathecal oxytocin and placebo groups (12.2 ± 10.7 vs 14.0 ± 13.0 min, respectively; p = 0.476). There was also no difference in cumulative vasopressor requirements (1303 ± 883 vs 1156 ± 818 μg [phenylephrine equivalents]; p = 0.413) during that time period. No group differences were found for any of the investigated secondary outcomes.

CONCLUSION

The administration of 100 μg of intrathecal oxytocin does not significantly impact the duration of hypotension or the need for vasopressor agents when given as a component of a spinal anesthetic. The oxytocin and placebo groups also did not differ in regards to physical therapy related metrics, time to first opioid administration, cumulative opioids at 24-h, or pain scores through 24-h. What is already known on this topic: Rapid intravenous oxytocin causes hypotension after cesarean delivery, but intrathecal oxytocin does not cause hypotension in healthy volunteers.

WHAT THIS STUDY ADDS

Compared to saline control, intrathecal oxytocin, 100 μg did not increase the duration of hypotension or vasopressor requirements in patients during total hip arthroplasty. How this study might affect research, practice, or policy: Lack of hypotension from intrathecal oxytocin in this study supports future investigations to further explore its potential benefits, in terms of both analgesia and functional recovery following surgery.

Effects of Adding Intrathecal Epinephrine to Spinal Anesthesia on Anesthesia-Related Cesarean Delivery Outcomes: Should We Reconsider Its Use?

BACKGROUND

 Intrathecal epinephrine is used to increase the duration of spinal anesthesia for amenable surgical procedures anticipated to require additional time; however, in the ambulatory setting, it is associated with a prolonged time to post-anesthesia care unit (PACU) discharge. The current study's authors hypothesized that adding intrathecal epinephrine to spinal anesthesia for cesarean delivery would be associated with a dose-dependent prolonged post-anesthesia unit length of stay.

METHODS

A single-center, retrospective study of patients undergoing repeat cesarean delivery under spinal anesthesia from 2011 to 2015 was conducted. Patients received spinal bupivacaine 12 mg, morphine 150 mcg, and fentanyl 15 mcg with no-epinephrine, 100 mcg, or 200 mcg of epinephrine. The primary outcome was recovery room length of stay. Secondary outcomes were surgical duration, intraoperative vasopressor use, perioperative opioids, and antiemetic use.

RESULTS

 Data were analyzed for 1,362 patients. Median recovery room stay was 123 min (interquartile range, 100 to 150) and was not different among groups. More women receiving epinephrine 200 mcg had ≥2 prior cesarean deliveries compared with no-epinephrine or 100 mcg. No significant differences in surgical duration or intraoperative opioids were identified among the groups. Median intraoperative vasopressor use was increased by 225 mcg of phenylephrine equivalents (99% CI, 25 mcg to 430 mcg) in the 100 mcg group and 250 mcg of phenylephrine equivalents in the 200 mcg group (99% CI, 75 mcg to 500 mcg) compared to no-epinephrine (P<0.001). Recovery room antiemetic and opioid analgesic administration were not different among groups.

CONCLUSIONS

 Based on the results of this study, the addition of intrathecal epinephrine for women undergoing cesarean delivery increases intraoperative vasopressor use but does not prolong PACU length of stay, reduce intraoperative opioids, or increase antiemetic requirements postoperatively. The current study also demonstrated that surgical duration times were not different among the no-epinephrine, 100 mcg, and 200 mcg epinephrine groups.

Impact of ketamine versus propofol for anesthetic induction on cognitive dysfunction, delirium, and acute kidney injury following cardiac surgery in elderly, high-risk patients

Objective

Evaluate the effects of ketamine versus propofol when used for induction of anesthesia in elderly, high-risk cardiac surgical patients on postoperative complications including cognitive dysfunction, delirium, and acute kidney injury.

Methods

Prospective, randomized study performed at a tertiary medical center. A total of 52 patients aged ≥70 and older presenting for complex cardiac surgery were randomized to receive either ketamine or propofol for induction of anesthesia. Patients underwent a battery of cognitive testing preoperatively and postoperatively and the incidence of delirium and acute kidney injury were measured. Norepinephrine (NEE) equivalents following induction were assessed for each group.

Results

A total of 49 patients were included, 25 in the ketamine group and 24 in the propofol group with 3 patients excluded from the analysis. No difference was found between groups in either postoperative cognitive dysfunction or delirium incidence. Acute kidney injury occurred in 6 (24%) patients in the ketamine group in 12 (50%) patients in the propofol group, but the difference did not meet statistical significance (P = 0.08; Relative Risk = 2.1, 95% CI 0.9-4.7). NEE equivalents were lower in the ketamine group, 9.6 ± 22.2 versus 32.7 ± 46.0, P < 0.03.

Conclusions

The use of ketamine versus propofol for induction of anesthesia did not impact the incidence of postoperative cognitive dysfunction or delirium. Twice as many patients in the propofol group developed acute kidney injury, although not reaching statistical significance and warranting further investigation. In elderly, high-risk patients, ketamine was associated with a significantly reduced need for vasopressor support following induction.

Effect of glycopyrrolate on vasopressor requirements for non-elective cesarean section under spinal anesthesia: a randomized, double-blind, placebo-controlled trial

Background

The study aimed to investigate whether prophylactic use of glycopyrrolate decreases the vasopressor requirements to prevent hypotension following spinal anesthesia during non-elective cesarean section.

Method

In this double-blind randomized clinical trial, 258 patients undergoing non-elective cesarean section were randomly assigned (1:1) to receive intravenous 0.2 mg glycopyrrolate or normal saline (placebo) before spinal anesthesia. The primary outcome was phenylephrine equivalent needed intraoperatively. Secondary outcomes included incidences of maternal hypotension, reactive hypertension, bradycardia, need for atropine, tachycardia, intraoperative nausea/vomiting, shivering, pruritus, dry mouth, dizziness; neonatal APGAR score at 1 min and 5 min, neonatal resuscitation needed, NICU admission and neonatal death.

Results

Three patients withdrew from the study due to failed spinal anesthesia. 128 patients in the glycopyrrolate group and 127 patients in the placebo group were analyzed. The mean phenylephrine equivalent needed was 1108.96 μg in the glycopyrrolate group and 1103.64 μg in the placebo group (mean difference, 5.32 μg [95% CI − 67.97 to 78.62]; P = 0.88). Hypotension occurred in 38 patients (30%) in the glycopyrrolate group as compared with 49 patients (39%) in the placebo group (P = 0.13). Tachycardia was reported in 70% of the participants in the glycopyrrolate group and 57% of those in the placebo group (P = 0.04). No statistically significant difference was noted in hypotensive episodes > 1, reactive hypertension, bradycardia, need for atropine, nausea, vomiting, shivering, and dry mouth between the two groups. Neonatal outcomes were similar in the two groups.

Conclusion

Prophylactic use of glycopyrrolate does not decrease the requirements of vasopressor to prevent hypotension in non-elective cesarean section under spinal anesthesia.

Trial registration

Registration number: NCT04401345. Date of registration: 26/05/2020. Website: https://clinicaltrials.gov

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.

Effects of different vasopressors on the contraction of the superior mesenteric artery and uterine artery in rats during late pregnancy

Background

Hypotension after neuraxial anaesthesia is one of the most common complications during caesarean section. Vasopressors are the most effective method to improve hypotension, but which of these drugs is best for caesarean section is not clear. We assessed the effects of vasopressors on the contractile response of uterine arteries and superior mesenteric arteries in pregnant rats to identify a drug that increases the blood pressure of the systemic circulation while minimally affecting the uterine and placental circulation.

Methods

Isolated ring segments from the uterine and superior mesenteric arteries of pregnant rats were mounted in organ baths, and the contractile responses to several vasopressor agents were studied. Concentration-response curves for norepinephrine, phenylephrine, metaraminol and vasopressin were constructed.

Results

The contractile response of the mesenteric artery to norepinephrine, as measured by the pEC50 of the drug, was stronger than the uterine artery (5.617 ± 0.11 vs. 4.493 ± 1.35, p = 0.009), and the contractile response of the uterine artery to metaraminol was stronger than the mesenteric artery (pEC50: 5.084 ± 0.17 vs. 4.92 ± 0.10, p = 0.007). There was no statistically significant difference in the pEC50 of phenylephrine or vasopressin between the two blood vessels.

Conclusions

In vitro experiments showed that norepinephrine contracts peripheral blood vessels more strongly and had the least effect on uterine artery contraction. These findings support the use of norepinephrine in mothers between the time of neuraxial anaesthesia and the delivery of the foetus.

Outcomes in patients with known contrast allergy undergoing contrast-enhanced endourological procedures: a retrospective cohort study

BACKGROUND

Intravenous administration of iodinated contrast agents carries the risk of allergic reaction, yet this risk is unclear with administration into the urinary tract. We sought to evaluate patients with known contrast, iodine, or shellfish allergies for allergic response when undergoing urologic imaging requiring intraluminal, urinary tract contrast administration.

MATERIALS AND METHODS

We retrospectively reviewed consecutive patients undergoing endourologic procedures from 2010 to 2015 at our institution. Clinical records were reviewed for demographics, medical history, allergies, procedure details, fluids administered, anesthetic and pharmacologic agents administered, and continuous monitoring parameters. Patients with known allergies to iodine, shellfish, and/or contrast were identified and evaluated for clinical or hemodynamic signs of allergy. A convenience sample of 50 patients without allergy history was used as a comparison group.

RESULTS

We identified 1,405 procedures involving 1,000 consecutive patients. Procedures included retrograde pyelograms and antegrade nephrostograms. Eighty-six cases involving 58 patients with contrast, iodine, or shellfish allergies were identified. Of those with contrast allergy history, 18 (20.1%) cases involved patients with a history of anaphylactic reaction. Of these, 11 (61%) received steroid prophylaxis. No patients in either group (Allergy, No Allergy) were identified as having an allergic reaction during the procedure. There were no statistically significant differences in intraoperative intravenous fluids (p=0.931), procedure duration (p=0.747), or vasopressor use (p=0.973) between groups. Due to the zero event rate of contrast allergy, we used the Hanley and Lippman-Hand method, which places true population risk (95% confidence interval) of a significant event at less than 3.5%.

CONCLUSIONS

In 86 cases involving patients with a history of contrast allergy, we found no evidence of clinically significant allergic reaction to intraluminal endourologic contrast administration under continuous anesthesia monitoring. The risk of significant reactions to contrast administered within the urinary tract appears to be low in these patients, regardless of prophylaxis.

Comparison of two vasopressor protocols for preventing hypotension post-spinal anesthesia during cesarean section: a randomized controlled trial

Background:

Norepinephrine infusion decreases hypotension after spinal anesthesia during cesarean section. This study aimed to compare the efficacy of norepinephrine infusion and ephedrine bolus against post-spinal hypotension in parturients.

Methods:

In this double-blinded, randomized controlled clinical trial, parturients scheduled for elective cesarean section were randomly allocated to receive norepinephrine infusion (0.05 μg·kg⁻¹·min⁻¹) just before spinal anesthesia continuing for 30 min or ephedrine bolus (0.15 mg/kg) just before spinal anesthesia. A rescue bolus (5 μg norepinephrine for the norepinephrine group, and 5 mg ephedrine for the ephedrine group) was administered whenever hypotension occurred. Our primary outcome was the incidence of hypotension within 30 min of spinal anesthesia administration. Secondary outcomes included maternal and neonatal outcomes 30 min after spinal block, and neonatal cerebral oxygenation 10 min after birth.

Results:

In total, 190 patients were enrolled; of these patients, 177 were included in the final analysis. Fewer patients suffered hypotension in the norepinephrine group than in the ephedrine group (29.5% vs. 44.9%, odds ratio [OR]: 0.51, 95% confidence interval [CI]: 0.28–0.95, P = 0.034). Moreover, the tachycardia frequency was lower in the norepinephrine group than in the ephedrine group (OR: 0.22, 95% CI: 0.11–0.44, P < 0.001), and patients suffered less nausea and vomiting (OR: 0.28, 95% CI: 0.11–0.70, P = 0.004). There was no difference in Apgar scores and umbilical arterial blood gas analysis between the two groups. However, neonatal cerebral regional saturations were significantly higher after birth in the norepinephrine group than in the ephedrine group (mean difference: 2.0%, 95% CI: 0.55%–3.45%, P = 0.008).

Conclusion:

In patients undergoing elective cesarean section with spinal anesthesia, norepinephrine infusion compared to ephedrine bolus resulted in less hypotension and tachycardia, and exhibited potential neonatal benefits.

Trial Registration:

ClinicalTrials.gov, NCT02542748; https://clinicaltrials.gov/ct2/show/record/NCT02542748

Effect of prophylactic combination of glycopyrrolate, ondansetron, and ephedrine upon hypotension during obstetric spinal anaesthesia–A randomised controlled trial

Background and Aims:

Various pharmacological and non-pharmacological strategies have been employed to minimise hypotension during obstetric spinal anaesthesia. We compared a prophylactic combination of glycopyrrolate, ondansetron, and ephedrine in terms of total vasopressor consumption, with standard treatment in this randomised controlled trial.

Methods:

One hundred patients undergoing elective caeserean sections were randomly divided into two groups of 50 each, the study group received prophylactic ondansetron and glycopyrrolate boluses followed by an infusion of ephedrine, while the control group received ephedrine boluses as required. The total ephedrine consumption (primary objective), incidence and degree of hypotension, heart rate variations, and neonatal APGAR scores (secondary objectives) were analysed.

Results:

The median ephedrine requirement was lesser in the study group compared to the control group [13.2 mg (10--15.75) vs. 27.7 mg (12--24)], with a P value of 0.02. Fewer participants experienced hypotension in the study group before baby delivery compared to the control group (12 vs. 36, P = 0.004). Heart rate was higher in the study group. No significant differences were observed in neonatal APGAR scores and incidence of adverse events.

Conclusion:

A combination of glycopyrrolate, ondansetron, and ephedrine might offer better haemodynamic stability and reduce vasopressor consumption in obstetric patients undergoing spinal anaesthesia as opposed to standard treatment.

Effects of intraoperative adrenergic administration on postoperative hyperlactatemia in open colon surgery: an observational study

Background

Postoperative Hyperlactatemia (PO-HL) is a frequent condition associated with poor prognosis. In recent years, there has been growing evidence that adrenergic stimulation may contribute to increased lactate levels. The use of adrenergic agonists for the control of intraoperative hypotension is frequent, and its impact on the development of PO-HL is unknown.

Objective

To evaluate whether the use of intraoperative adrenergic agents is associated with the occurrence of PO-HL.

Methods

This was a prospective observational study. The inclusion criteria were undergoing elective open colon surgery, being ≥60 years old and signing informed consent. The exclusion criteria were cognitive impairment, unplanned surgery, and anticipated need for postoperative mechanical ventilation. Baseline and intraoperative variables were collected, and arterial lactate data were collected at baseline and every 6 hours postoperatively for 24 hours. Hyperlactatemia was defined as lactate >2.1 mEq.L^-1.

Results

We studied 28 patients, 61% of whom developed hyperlactatemia. The variables associated with PO-HL in the univariate analysis were anesthetic time, the total dose of intraoperative ephedrine, and lower intraoperative central venous oxygen saturation (ScvO₂). Multivariate analysis confirmed the association between the use of ephedrine (p = 0.004), intraoperative hypotension (p = 0.026), and use of phenylephrine (p = 0.001) with PO-HL.

Conclusions

The use of intraoperative ephedrine, phenylephrine and intraoperative hypotension were independently associated with the development of PO-HL. This finding should lead to new studies in this field, as well as a judicious interpretation of the finding of a postoperative increase in lactate levels.

Effect of Different Positions During Surgical Preparation With Combined Spinal-Epidural Anesthesia for Elective Cesarean Delivery: A Randomized Controlled Trial

BACKGROUND

The intraoperative 15° left-tilt position during cesarean delivery has more recently been questioned regarding its effect on fetal acid-base balance and is a frequent source of complaints by surgeons. We hypothesized that a 30° left-tilt position during surgical preparation could improve the acid-base balance of the fetus compared with the 15° left-tilt or supine position during surgical preparation.

METHODS

Women undergoing elective cesarean delivery under combined spinal epidural anesthesia were randomized to a supine position, 15° left-lateral tilt position or 30° left-lateral tilt position; the position was changed to supine before the incision. Anesthetic management was standardized and included fluid loading with 10 mL/kg of normal saline followed by colloid loading. Hypotension (systolic blood pressure [SBP] reduction >20% baseline value or SBP <90 mm Hg) was treated with boluses of phenylephrine or ephedrine according to maternal heart rate. The primary outcome was umbilical arterial blood pH and the secondary outcomes included maternal SBP within 15 minutes after induction of anesthesia, the amount of vasoactive drug administered before end of the surgery, and the incidence of hypotension during cesarean delivery.

RESULTS

Seventy-five patients were included. After testing by analysis of variance, there was no significant difference in the umbilical arterial pH among the 3 groups (supine group: 7.31 ± 0.03 vs 15° group: 7.30 ± 0.04 vs 30° group: 7.31 ± 0.02, P = .28). The 30° group required significantly less phenylephrine (P = .007) and ephedrine (P = .005) before the end of surgery than the supine group; however, the only benefit observed in the 15° group was that the mean SBP at 3 minutes after spinal injection was significantly improved compared with the supine group.

CONCLUSIONS

Compared with the supine position, the 30° left-tilt position during surgical preparation did not significantly improve the fetal acid-base status, but it significantly reduced the use of phenylephrine and ephedrine and reduced the incidence of hypotension; however, these benefits were not observed in the 15° left-tilt group.

The effect of preoperative anxiety on phenylephrine dose during cesarean delivery: An open controlled one-arm clinical trial

BACKGROUND

We performed an open controlled one-arm clinical trial to assess whether preoperative anxiety influences phenylephrine dosage required to maintain normotension during cesarean section under spinal anesthesia.

METHODS

Ninety-four parturients undergoing elective cesarean delivery under spinal anesthesia were included. Anxiety levels were measured using a verbal numerical scale anxiety score (0-10). Phenylephrine infusion to prevent hypotension was adjusted by a standard algorithm. The primary outcome was total phenylephrine dose. Linear uni- and multivariate regressions were performed to assess the relationship between preoperative anxiety and the outcome. P < .05 was considered statistically significant.

RESULTS

We found no association between preoperative anxiety and phenylephrine dosage (R²  = 0.05). Taking the number of attempts for spinal anesthesia and surgical time into account did not lead to a significant improvement of the regression model.

CONCLUSION

In conclusion, we did not find a large independent effect of preoperative anxiety on phenylephrine dose required to maintain normotension in our cohort. We believe that spinal hypotension and phenylephrine dose requirement are multifactorial and anxiety is only one of the factors in this complex interaction.

Effects of laparoscopic vs open abdominal surgery on costs and hospital readmission rate and its effect modification by surgeons' case volume

BACKGROUND

Laparoscopy provides a minimally invasive alternative to open abdominal surgery. Current data describing its association with hospital readmission and costs in relation to surgeon laparoscopic case volume is limited to smaller databases and subsets of operations.

METHODS

This retrospective cohort study of 23,285 adult abdominal operations from 2007 to 2015 compares 30-day readmission rate and costs between laparoscopic and open abdominal operations and examines effect modification by surgeon laparoscopic case volume. Outcomes were all-cause hospital readmission within 30 days after discharge and index hospital admission cost.

RESULTS

All-cause hospital readmission rates were significantly lower after laparoscopic abdominal operations compared with open operations (adjusted odds ratio [aOR] 0.56, 95% CI 0.46-0.69, p < 0.001) with a difference in readmission risk attributable to laparoscopic approach of - 4.0% (95% CI - 5.4 to - 2.6%) in complete-case analysis. Among surgeons with a high laparoscopic case volume, the estimated difference in readmission risk through laparoscopy was magnified (- 5.8%, 95% CI - 7.5 to - 4.1%) compared to low surgeon laparoscopic case volume (- 2.9%, 95% CI - 4.8 to -1.1%, p for interaction = 0.005). The estimated difference in costs of the index hospital admission attributable to laparoscopic approach was - $3869 (95% CI - $4200 to - $3538; adjusted incidence rate ratio 0.77, 95% CI 0.75-0.79, p < 0.001). Laparoscopy was followed by significantly lower rates of readmissions related to gastrointestinal (aOR 0.68, 95% CI 0.55-0.85, p = 0.001), wound complications (infection: aOR 0.33, 95% CI 0.23-0.47, p < 0.001; non-infectious: aOR 0.47, 95% CI 0.30-0.74, p = 0.001), and malignancy (aOR 0.68, 95% CI 0.55-0.85, p < 0.001). The findings remain robust after multiple imputation and sensitivity analyses.

CONCLUSIONS

Laparoscopy versus open abdominal surgery is associated with reduced hospital readmissions related to malignancy, gastrointestinal, and wound complications. Effect modification by higher laparoscopy case volume argues for continued proliferation of laparoscopy in abdominal surgeries.

Patent foramen ovale and long-term risk of ischaemic stroke after surgery

AIMS

Pre-operatively diagnosed patent foramen ovale (PFO) is associated with an increased risk of ischaemic stroke within 30 days after surgery. This study aimed to assess the PFO-attributable ischaemic stroke risk beyond the perioperative period.

METHODS AND RESULTS

This observational study of adult patients without history of stroke undergoing non-cardiac surgery with general anaesthesia examined the association of PFO with ischaemic stroke 1 and 2 years after surgery using multivariable logistic regression. Of the 144 563 patients included, a total of 1642 (1.1%) and 2376 (1.6%) ischaemic strokes occurred within 1 and 2 years after surgery, 54 (4.7%) and 76 (6.6%) among patients with PFO, and 1588 (1.1%) and 2300 (1.6%) among patients without PFO, respectively. The odds of ischaemic stroke within 1 and 2 years after surgery were increased in patients with PFO: adjusted odds ratio (aOR) 2.01, 95% confidence interval (CI) 1.51-2.69; P < 0.001 and aOR 2.10, 95% CI 1.64-2.68; P < 0.001, respectively. Among patients who underwent contrast transoesophageal echocardiography, the frequency of PFO was 27%, and the increased stroke risk in patients with PFO was robust (aOR 3.80, 95% CI 1.76-8.23; P = 0.001 for year 1). The PFO-attributable risk was mitigated by post-operative prescription of combination antithrombotic therapy (odds ratio 0.41, 95% CI 0.22-0.75; P for interaction = 0.004).

CONCLUSION

Patients with PFO are vulnerable to ischaemic stroke for an extended period of time after surgery. Physicians should consider implementing PFO screening protocols in patients scheduled for major non-cardiac surgery.

Adverse heart rate responses during beach-chair position for shoulder surgeries - A systematic review and meta-analysis of their incidence, interpretations and associations

Background and Aims

Evaluations of adverse heart rate (HR)-responses and HR-variations during anaesthesia in beach-chair-position (BCP) for shoulder surgeries have not been done earlier. We analysed the incidence, associations, and interpretations of adverse HR-responses in this clinical setting.

Methods

We performed a meta-analysis of trials that reported HR-related data in anaesthetised subjects undergoing elective shoulder surgeries in BCP. Studies included prospective, randomised, quasi-randomised and non-randomised, controlled clinical trials as well as observational cohorts. Literature search was conducted in MEDLINE, EMBASE, CINHAL and the Cochrane Central Register of Controlled Trials of the 21^st century. In the first analysis, we studied the incidence and associations of bradycardia/hypotension-bradycardia episodes (HBE) with respect to the type of anaesthesia and different pharmacological agents. In the second, we evaluated anaesthetic influences, associations and inter-relationships between monitored parameters with respect to HR-behaviours.

Results

Among the trials designed with bradycardia/HBE as a primary end point, the observed incidence of bradycardia was 9.1% and that of HBE, 14.9% and 22.7% [(for Interscalene block (ISB) ± sedation) subjects and general anaesthesia (GA) + ISB, respectively]. There was evidence of higher observed risk of developing adverse HR-responses for GA subjects over ISB (Risk Difference, P < 0.05). Concomitant use of β-agonists did not increase risk of HBEs (P = 0.29, I ²= 11.4%) or with fentanyl (P = 0.45, I ²= 0%) for ISB subjects (subgroup analysis). Fentanyl significantly influenced the HR-drop over time [meta-regression, estimates (standard error), 14.9 (5.4), 9.8 (4.3) and 17 (2.6); P = 0.007, 0.024 and <0.001; for early, mid and delayed periods, respectively] in GA subjects. With respect to number of subjects experiencing cerebral desaturation events (CDEs), total intravenous anaesthesia (TIVA)- propofol had higher risk over inhalational anaesthesia (P = 0.006, I ² = 86.7%). Meta-correlation analysis showed relationships between the HR and rSO₂(regional cerebral oxygen saturation) or SjvO₂(jugular venous oxygen saturation) values (r = 0.608, 95%CI, 0.439 to 0.735, P < 0.001, I ²= 77.4% and r = 0.397, 95%CI, 0.151 to 0.597, P < 0.001, I ²= 64.3%, respectively).

Conclusions

There is not enough evidence to claim the associations of adverse HR-responses with any specific factor. HR-fall is maximal with fentanyl and its variability is associated with changes in rSO₂. Fall in rSO₂ could be the common link triggering adverse HR-responses in BCP.

Techniques for preventing hypotension during spinal anaesthesia for caesarean section

BACKGROUND

Maternal hypotension is the most frequent complication of spinal anaesthesia for caesarean section. It can be associated with nausea or vomiting and may pose serious risks to the mother (unconsciousness, pulmonary aspiration) and baby (hypoxia, acidosis, neurological injury).

OBJECTIVES

To assess the effects of prophylactic interventions for hypotension following spinal anaesthesia for caesarean section.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (9 August 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials, including full texts and abstracts, comparing interventions to prevent hypotension with placebo or alternative treatment in women having spinal anaesthesia for caesarean section. We excluded studies if hypotension was not an outcome measure.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study quality and extracted data from eligible studies. We report 'Summary of findings' tables using GRADE.

MAIN RESULTS

We included 125 studies involving 9469 women. Interventions were to prevent maternal hypotension following spinal anaesthesia only, and we excluded any interventions considered active treatment. All the included studies reported the review's primary outcome. Across 49 comparisons, we identified three intervention groups: intravenous fluids, pharmacological interventions, and physical interventions. Authors reported no serious adverse effects with any of the interventions investigated. Most trials reported hypotension requiring intervention and Apgar score of less than 8 at five minutes as the only outcomes. None of the trials included in the comparisons we describe reported admission to neonatal intensive care unit. Crystalloid versus control (no fluids) Fewer women experienced hypotension in the crystalloid group compared with no fluids (average risk ratio (RR) 0.84, 95% confidence interval (CI) 0.72 to 0.98; 370 women; 5 studies; low-quality evidence). There was no clear difference between groups in numbers of women with nausea and vomiting (average RR 0.19, 95% CI 0.01 to 3.91; 1 study; 69 women; very low-quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (60 babies, low-quality evidence). Colloid versus crystalloid Fewer women experienced hypotension in the colloid group compared with the crystalloid group (average RR 0.69, 95% CI 0.58 to 0.81; 2009 women; 27 studies; very low-quality evidence). There were no clear differences between groups for maternal hypertension requiring intervention (average RR 0.64, 95% CI 0.09 to 4.46, 3 studies, 327 women; very low-quality evidence), maternal bradycardia requiring intervention (average RR 0.98, 95% CI 0.54 to 1.78, 5 studies, 413 women; very low-quality evidence), nausea and/or vomiting (average RR 0.89, 95% CI 0.66 to 1.19, 14 studies, 1058 women, I² = 29%; very low-quality evidence), neonatal acidosis (average RR 0.83, 95% CI 0.15 to 4.52, 6 studies, 678 babies; very low-quality evidence), or Apgar score of less than 8 at five minutes (average RR 0.24, 95% CI 0.03 to 2.05, 10 studies, 730 babies; very low-quality evidence). Ephedrine versus phenylephrine There were no clear differences between ephedrine and phenylephrine groups for preventing maternal hypotension (average RR 0.92, 95% CI 0.71 to 1.18; 401 women; 8 studies; very low-quality evidence) or hypertension (average RR 1.72, 95% CI 0.71 to 4.16, 2 studies, 118 women, low-quality evidence). Rates of bradycardia were lower in the ephedrine group (average RR 0.37, 95% CI 0.21 to 0.64, 5 studies, 304 women, low-quality evidence). There was no clear difference in the number of women with nausea and/or vomiting (average RR 0.76, 95% CI 0.39 to 1.49, 4 studies, 204 women, I² = 37%, very low-quality evidence), or babies with neonatal acidosis (average RR 0.89, 95% CI 0.07 to 12.00, 3 studies, 175 babies, low-quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (321 babies; low-quality evidence). Ondansetron versus control Ondansetron administration was more effective than control (placebo saline) for preventing hypotension requiring treatment (average RR 0.67, 95% CI 0.54 to 0.83; 740 women, 8 studies, low-quality evidence), bradycardia requiring treatment (average RR 0.49, 95% CI 0.28 to 0.87; 740 women, 8 studies, low-quality evidence), and nausea and/or vomiting (average RR 0.35, 95% CI 0.24 to 0.51; 653 women, 7 studies, low-quality evidence). There was no clear difference between the groups in rates of neonatal acidosis (average RR 0.48, 95% CI 0.05 to 5.09; 134 babies; 2 studies, low-quality evidence) or Apgar scores of less than 8 at five minutes (284 babies, low-quality evidence). Lower limb compression versus control Lower limb compression was more effective than control for preventing hypotension (average RR 0.61, 95% CI 0.47 to 0.78, 11 studies, 705 women, I² = 65%, very low-quality evidence). There was no clear difference between the groups in rates of bradycardia (RR 0.63, 95% CI 0.11 to 3.56, 1 study, 74 women, very low-quality evidence) or nausea and/or vomiting (average RR 0.42, 95% CI 0.14 to 1.27, 4 studies, 276 women, I² = 32%, very-low quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (130 babies, very low-quality evidence). Walking versus lying There was no clear difference between the groups for women with hypotension requiring treatment (RR 0.71, 95% CI 0.41 to 1.21, 1 study, 37 women, very low-quality evidence). Many included studies reported little to no information that would allow an assessment of their risk of bias, limiting our ability to draw meaningful conclusions. GRADE assessments of the quality of evidence ranged from very low to low. We downgraded evidence for limitations in study design, imprecision, and indirectness; most studies assessed only women scheduled for elective caesarean sections. External validity also needs consideration. Readers should question the use of colloids in this context given the serious potential side effects such as allergy and renal failure associated with their administration.

AUTHORS' CONCLUSIONS

While interventions such as crystalloids, colloids, ephedrine, phenylephrine, ondansetron, or lower leg compression can reduce the incidence of hypotension, none have been shown to eliminate the need to treat maternal hypotension in some women. We cannot draw any conclusions regarding rare adverse effects associated with use of the interventions (for example colloids) due to the relatively small numbers of women studied.

Control of Spinal Anesthesia-Induced Hypotension in Adults

Spinal anesthesia-induced hypotension (SAIH) occurs frequently, particularly in the elderly and in patients undergoing caesarean section. SAIH is caused by arterial and venous vasodilatation resulting from the sympathetic block along with a paradoxical activation of cardioinhibitory receptors. Bradycardia after spinal anesthesia (SA) must always be treated as a warning sign of an important hemodynamic compromise. Fluid preloading (before initiation of the SA) with colloids such as hydroxyethyl starch (HES) effectively reduces the incidence and severity of arterial hypotension, whereas crystalloid preloading is not indicated. Co-loading with crystalloid or colloid is as equally effective to HES preloading, provided that the speed of administration is adequate (ie, bolus over 5 to 10 minutes). Ephedrine has traditionally been considered the vasoconstrictor of choice, especially for use during SAIH associated with bradycardia. Phenylephrine, a α₁ adrenergic receptor agonist, is increasingly used to treat SAIH and its prophylactic administration (ie, immediately after intrathecal injection of local anesthetics) has been shown to decrease the incidence of arterial hypotension. The role of norepinephrine as a possible alternative to phenylephrine seems promising. Other drugs, such as serotonin receptor antagonists (ondansetron), have been shown to limit the blood pressure drop after SA by inhibiting the Bezold–Jarisch reflex (BJR), but further studies are needed before their widespread use can be recommended.

Effect of Phenylephrine and Ephedrine on Cerebral (Tissue) Oxygen Saturation During Carotid Endarterectomy (PEPPER): A Randomized Controlled Trial

Background

Short-acting vasopressor agents like phenylephrine or ephedrine can be used during carotid endarterectomy (CEA) to achieve adequate blood pressure (BP) to prevent periprocedural stroke by preserving the cerebral perfusion. Previous studies in healthy subjects showed that these vasopressors also affected the frontal lobe cerebral tissue oxygenation (rSO₂) with a decrease after administration of phenylephrine. This decrease is unwarranted in patients with jeopardized cerebral perfusion, like CEA patients. The study aimed to evaluate the impact of both phenylephrine and ephedrine on the rSO₂ during CEA.

Methods

In this double-blinded randomized controlled trial, 29 patients with symptomatic carotid artery stenosis underwent CEA under volatile general anesthesia in a tertiary referral medical center. Patients were preoperative allocated randomly (1:1) for receiving either phenylephrine (50 µg; n = 14) or ephedrine (5 mg; n = 15) in case intraoperative hypotension occurred, defined as a decreased mean arterial pressure (MAP) ≥ 20% compared to (awake) baseline. Intraoperative MAP was measured by an intra-arterial cannula placed in the radial artery. After administration, the MAP, cardiac output (CO), heart rate (HR), stroke volume, and rSO₂ both ipsilateral and contralateral were measured. The timeframe for data analysis was 120 s before, until 600 s after administration.

Results

Both phenylephrine (70 ± 9 to 101 ± 22 mmHg; p < 0.001; mean ± SD) and ephedrine (75 ± 11 mmHg to 122 ± 22 mmHg; p < 0.001) adequately restored MAP. After administration, HR did not change significantly over time, and CO increased 19% for both phenylephrine and ephedrine. rSO₂ ipsilateral and contralateral did not change significantly after administration at 300 and 600 s for either phenylephrine or ephedrine (phenylephrine 73%, 73%, 73% and 73%, 73%, 74%; ephedrine 72%, 73%, 73% and 75%, 74%, 74%).

Conclusions

Within this randomized prospective study, MAP correction by either phenylephrine or ephedrine showed to be equally effective in maintaining rSO₂ in patients who underwent CEA.

Clinical Trial Registration ClincalTrials.gov, NCT01451294.

A randomized double-blind study comparing prophylactic norepinephrine and ephedrine infusion for preventing maternal spinal hypotension during elective cesarean section under spinal anesthesia: A CONSORT-compliant article

BACKGROUND

Studies have shown the efficacy of norepinephrine in the treatment of maternal hypotension during cesarean section by comparing it to treatment with phenylephrine. However, few studies have compared the efficacy of norepinephrine to ephedrine.

METHODS

Ninety-seven women undergoing elective cesarean section were administered norepinephrine at 4 μg/minute (group N; n = 48) or ephedrine at 4 mg/minute (group E; n = 49) immediately postspinal anesthesia, with an on-off titration to maintain systolic blood pressure (SBP) at 80% to 120% of baseline. A rescue bolus of 8 μg norepinephrine was given whenever SBP reached the predefined lower limit. Our primary outcome was the incidence of tachycardia. Secondary outcomes included the incidence of bradycardia, hypertension, hypotension, severe hypotension, hypotensive episodes, number of rescue top-ups, hemodynamic performance error including median performance error (MDPE), and median absolute performance error (MDAPE). Neonatal Apgar scores and umbilical arterial (UA) blood gas data were also collected.

RESULTS

Women in group N experienced fewer cases of tachycardia (4.2% vs 30.6%, P = .002, odds ratio: 0.11 [95% confidence interval, CI: 0.02-0.47]), a lower standardized heart rate (HR) (70.3 ± 11 vs 75 ± 11, P = .04, difference: 4.7 ± 2.2 [95% CI: 0.24-9.1]), and a lower MDPE for HR (1.3 ± 9.6 vs 8.4 ± 13.5 bpm, P = .003, difference: 3.1 ± 1.8 [95% CI: -0.6-6.7]). In addition, the lowest or the highest HR was lower in group N compared to group E (both P < .05). Meanwhile, the standardized SBP in group N was lower than that in group E (P = .04). For neonates, the UA blood gas showed a higher base excess (BE) and a lower lactate level in group N compared to E (both P < .001). Other hemodynamic variables, maternal, and neonatal outcomes were similar.

CONCLUSION

Infusion of 4 μg/minute norepinephrine presented fewer cases of tachycardia, less fluctuation and a lower HR compared to baseline values, as well as a less stressed fetal status compared to ephedrine infusion at 4 mg/minute. In addition, norepinephrine infusion presented a lower standardized SBP compared to ephedrine.

Volume-Controlled Versus Dual-Controlled Ventilation during Robot-Assisted Laparoscopic Prostatectomy with Steep Trendelenburg Position: A Randomized-Controlled Trial

Dual-controlled ventilation (DCV) combines the advantages of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). Carbon dioxide (CO₂) pneumoperitoneum and steep Trendelenburg positioning for robot-assisted laparoscopic radical prostatectomy (RALRP) has negative effects on the respiratory system. We hypothesized that the use of autoflow as one type of DCV can reduce these effects during RALRP. Eighty patients undergoing RALRP were randomly assigned to receive VCV or DCV. Arterial oxygen tension (PaO₂) as the primary outcome, respiratory and hemodynamic data, and postoperative fever rates were compared at four time points: 10 min after anesthesia induction (T1), 30 and 60 min after the initiation of CO₂ pneumoperitoneum and Trendelenburg positioning (T2 and T3), and 10 min after supine positioning (T4). There were no significant differences in PaO₂ between the two groups. Mean peak airway pressure (Ppeak) was significantly lower in group DCV than in group VCV at T2 (mean difference, 5.0 cm H₂O; adjusted p < 0.001) and T3 (mean difference, 3.9 cm H₂O; adjusted p < 0.001). Postoperative fever occurring within the first 2 days after surgery was more common in group VCV (12%) than in group DCV (3%) (p = 0.022). Compared with VCV, DCV did not improve oxygenation during RALRP. However, DCV significantly decreased Ppeak without hemodynamic instability.

Neuraxial Anesthesia During Cesarean Delivery for Placenta Previa With Suspected Morbidly Adherent Placenta: A Retrospective Analysis

BACKGROUND

General anesthesia (GA) is often selected for cesarean deliveries (CD) with placenta previa and suspected morbidly adherent placenta (MAP) due to increased risk of hemorrhage and hysterectomy. We reviewed maternal outcomes and risk factors for conversion to GA in a cohort of patients undergoing CD and hysterectomy under neuraxial anesthesia (NA).

METHODS

We performed a single-center, retrospective cohort study of parturients undergoing nonemergent CD for placenta previa with suspected MAP from 1997 to 2015. Patients were classified according to whether they received GA, NA, or intraoperative conversion from NA to GA. The primary outcome measure was postoperative acuity, defined as the need for intensive care unit admission, arterial embolization, reoperation, or ongoing transfusion with ≥3 units packed red blood cells. We additionally identified variables positively associated with intraoperative conversion from NA to GA during hysterectomy. Confounding was controlled with logistic regression models.

RESULTS

Of 129 patients undergoing nonemergent CD for placenta previa with suspected MAP, 122 (95%) received NA as the primary anesthetic. NA was selected in the majority of patients with a body mass index ≥40 kg/m (9 of 10, 90%), a history of ≥3 prior CDs (18 of 20, 90%), suspected placenta increta or percreta (29 of 35, 83%), and Mallampati classification ≥3 (19 of 21, 90%). Of 72 patients with NA at the time of delivery who required hysterectomy, 15 (21%) required conversion to GA intraoperatively. Converted patients had a higher rate of major packed red blood cell transfusion (60% vs 25%; P = .01), with similar rates of massive transfusion (9% vs 7%; P = 1.0). Converted patients also had a higher incidence of postoperative acuity (47% vs 4%; P < .0001), including 5 intensive care unit admissions for airway management after large-volume resuscitation. After adjusting for multiple confounders, the only independent predictors of conversion among hysterectomy patients were longer surgical duration (adjusted odds ratio 1.54, 95% CI, 1.01-2.42) and a history of ≥3 prior CDs (adjusted odds ratio, 6.45; 95% CI, 1.12-45.03).

CONCLUSIONS

NA was applied to and successfully used in the majority of patients with suspected MAP. Our findings support selective conversion to GA during hysterectomy in these patients, focusing on those with the highest levels of surgical complexity.

The Effect of Prophylactic Phenylephrine and Ephedrine Infusions on Umbilical Artery Blood pH in Women With Preeclampsia Undergoing Cesarean Delivery With Spinal Anesthesia: A Randomized, Double-Blind Trial

BACKGROUND

Spinal anesthesia for cesarean delivery is associated with a high incidence of hypotension. Phenylephrine results in higher umbilical artery pH than ephedrine when used to prevent or treat hypotension in healthy women. We hypothesized that phenylephrine compared to ephedrine would result in higher umbilical artery pH in women with preeclampsia undergoing cesarean delivery with spinal anesthesia.

METHODS

This study was a randomized double-blind clinical trial. Nonlaboring women with preeclampsia scheduled for cesarean delivery with spinal anesthesia at Prentice Women's Hospital of Northwestern Medicine were randomized to receive prophylactic infusions of phenylephrine or ephedrine titrated to maintain systolic blood pressure >80% of baseline. Spinal anesthesia consisted of hyperbaric 0.75% bupivacaine 12 mg, fentanyl 15 µg, and morphine 150 µg. The primary outcome was umbilical arterial blood pH and the secondary outcome was umbilical artery base excess.

RESULTS

One hundred ten women were enrolled in the study and 54 per group were included in the analysis. There were 74 and 72 infants delivered in the ephedrine and phenylephrine groups, respectively. The phenylephrine:ephedrine ratio for umbilical artery pH was 1.002 (95% confidence interval [CI], 0.997-1.007). Mean [standard deviation] umbilical artery pH was not different between the ephedrine 7.20 [0.10] and phenylephrine 7.22 [0.07] groups (mean difference -0.02, 95% CI of the difference -0.06 to 0.07; P = .38). Median (first, third quartiles) umbilical artery base excess was -3.4 mEq/L (-5.7 to -2.0 mEq/L) in the ephedrine group and -2.8 mEq/L (-4.6 to -2.2mEq/L) in the phenylephrine group (difference -0.6 mEq/L, 95% CI of the difference -1.6 to 0.3 mEq/L; P = .10). When adjusted for gestational age and infant gender, umbilical artery pH did not differ between groups. There were also no differences in the umbilical artery pH stratified by magnesium therapy or by the severity of preeclampsia.

CONCLUSIONS

We were unable to demonstrate a beneficial effect of phenylephrine on umbilical artery pH compared with ephedrine. Our findings suggest that phenylephrine may not have a clinically important advantage compared with ephedrine with regard to improved neonatal acid-base status when used to prevent spinal anesthesia-induced hypotension in women with preeclampsia undergoing cesarean delivery.

Effects of low-dose intraoperative fentanyl on postoperative respiratory complication rate: a pre-specified, retrospective analysis

BACKGROUND

Fentanyl is one of the most frequently administered intraoperative drugs and may increase the risk of postoperative respiratory complications (PRCs).

METHODS

We performed a pre-specified analysis of 145 735 adult non-cardiac surgical cases under general anaesthesia. Using multivariable logistic regression, we evaluated the association of intraoperative fentanyl dose and PRCs within 3 days after surgery (defined as reintubation, respiratory failure, pneumonia, pulmonary oedema, or atelectasis). We examined effect modification by patient characteristics, surgical site, and anaesthetics used.

RESULTS

PRCs within 3 days after surgery occurred in 18 839 (12.9%) patients. In comparison with high intraoperative fentanyl doses [median: 3.85; inter-quartile range (IQR): 3.42-4.50 μg kg^-1, quartile 4 (Q4)], low intraoperative fentanyl dose [median: 0.80, IQR: 0.00-1.14 μg kg^-1, quartile 1 (Q1)] was significantly associated with lower odds of PRCs [Q1 vs Q4: 10.9% vs 16.2%; adjusted odds ratio (aOR) 0.79; 95% confidence intervals (CI) 0.75-0.84; P<0.001; adjusted absolute risk difference (aARD) -1.7%]. This effect was augmented by thoracic surgery (P for interaction <0.001; aARD -6.2%), high doses of inhalation anaesthetics (P for interaction=0.016; aARD -2.2%) and neuromuscular blocking agents (NMBAs) (P for interaction=0.001; aARD -3.4%). Exploratory analysis demonstrated that compared with no fentanyl, low-dose fentanyl was associated with lower rates of PRCs (decile 2 vs decile 1: aOR 0.82, CI 0.75-0.89, P<0.001).

CONCLUSIONS

Intraoperative low-dose fentanyl (about 60-120 μg for a 70 kg patient) was associated with lower risk of postoperative respiratory complications compared with both no fentanyl and high-dose fentanyl. Beneficial effects of low-dose fentanyl were magnified in specific patient subgroups.

CLINICAL TRIAL REGISTRATION

NCT03198208.

A Comparative Study of Bolus Norepinephrine, Phenylephrine, and Ephedrine for the Treatment of Maternal Hypotension in Parturients with Preeclampsia During Cesarean Delivery Under Spinal Anesthesia

Background

This study aimed to compare the efficacy and safety of bolus norepinephrine, phenylephrine, and ephedrine in parturient with preeclampsia who had hypotension during cesarean delivery under spinal anesthesia.

Material/Methods

One hundred and sixty-six parturient women with preeclampsia who had a baseline systolic blood pressure (SBP) <80% during spinal anesthesia for cesarean section were divided into three treatment groups; bolus norepinephrine 4 μg (group N) (n=56), phenylephrine 50 μg (group P) (n=55), and ephedrine 4 mg (group E) (n=55). Primary outcomes included overall SBP and heart rate (HR) until delivery. Secondary outcomes included the incidence of tachycardia (HR >120 bpm), bradycardia (HR <60 bpm), hypertension (SBP >120% baseline), number of boluses of vasopressor required and episodes of hypotension, maternal side effects, and neonatal outcome.

Results

Overall HR in group N was significantly increased compared with group P (80.5±12 vs. 76.6±6.9 bpm; P=0.04), and significantly lower compared with group E (80.5±12 vs. 84.9±7.1 bpm; P=0.02). Parturients in group N had fewer episodes of bradycardia compared with group P (3.6% vs. 21.8%; RR=0.26l; 95% CI, 0.07–0.73; P=0.004) and fewer episodes of tachycardia compared with group E (16.1% vs. 36.4%; RR 0.54; 95% CI, 0.29–0.90; P=0.02).

Conclusions

A bolus dose of norepinephrine showed similar efficacy to phenylephrine but improved maternal and neonatal safety in parturients with preeclampsia with hypotension during cesarean section under spinal anesthesia.

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.

Patient quality of recovery on the day of surgery after propofol total intravenous anesthesia for vitrectomy: A randomized controlled trial

BACKGROUND

Vitrectomy under general anesthesia is considered as a candidate for ambulatory surgery. An anesthetic method with high quality of postoperative recovery should be selected for successful ambulatory surgery. We thus compared quality of postoperative recovery on the day of vitrectomy using the Quality of Recovery (QoR)-40 questionnaire between propofol total intravenous anesthesia (propofol group) and desflurane inhalation anesthesia (desflurane group) as the 2 representative anesthetic methods.

METHODS

Eighty-four patients (20-80 years old) undergoing elective vitrectomy under general anesthesia were randomized into 2 groups. The propofol group received propofol and remifentanil using effect-site target-controlled infusion (TCI), and the desflurane group received desflurane inhalation and remifentanil using effect-site TCI. We assessed quality of recovery at 6 hours after surgery through interviews using the QoR-40 questionnaire. We also collected data related to recovery and complications during emergence and recovery period.

RESULTS

The median of QoR-40 score on the day of surgery was significantly higher in the propofol group than that in the desflurane group (181.0 vs 169.5, respectively; P = .033). In particular, propofol group had significantly higher scores for physical comfort and physical independence dimensions. The amount of remifentanil administered was significantly higher, and the emergence time was significantly longer in propofol group. However, there were no significant differences in other complications between the 2 groups.

CONCLUSIONS

Propofol total intravenous anesthesia provided significantly better quality of recovery on the day of surgery than desflurane inhalation anesthesia.

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.

Combined spinal-epidural vs. spinal anaesthesia for caesarean section: meta-analysis and trial-sequential analysis

Combined spinal-epidural and single-shot spinal anaesthesia are both used for caesarean section. It has been claimed in individual trials that combined spinal-epidural is associated with higher sensory spread and greater cardiovascular stability. We set out to gather all available evidence. We performed: a systematic literature search to identify randomised controlled trials comparing combined spinal-epidural with spinal anaesthesia for caesarean section: conventional meta-analysis; trial-sequential analysis; and assessment of trial quality using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Fifteen trials with high heterogeneity, including 1015 patients, were analysed. There was no significant difference between combined spinal-epidural and spinal anaesthesia for our primary outcomes maximum sensory height and vasopressor use (mg ephedrine equivalents). However, trial-sequential analysis suggested insufficient data and the GRADE scores showed 'very low' quality of evidence for these outcomes. The secondary outcomes hypotension, time for sensory block to recede to the level of T10, and the combined outcome of nausea and vomiting, did not differ significantly between the interventions. The block times were statistically significantly longer for combined spinal-epidural in individual trials, but only one trial showed a clinically meaningful difference (11 min). Based on this analysis, and taking into consideration all comparisons irrespective of whether drugs had been applied via the epidural route, there is not enough evidence to postulate any advantage compared with the spinal technique. Future analyses and studies need to examine the potential advantages of the combined spinal-epidural technique by using the epidural route intra- and/or postoperatively.

The impact of neuraxial clonidine on postoperative analgesia and perioperative adverse effects in women having elective Caesarean section-a systematic review and meta-analysis

Neuraxial clonidine improves postoperative analgesia in the general surgical population. The efficacy and safety of neuraxial clonidine as a postoperative analgesic adjunct in the Caesarean section population still remains unclear. This systematic review and meta-analysis aims to evaluate the effect of perioperative neuraxial clonidine on postoperative analgesia in women having Caesarean section under neuraxial anaesthesia. We included randomized controlled trials comparing the analgesic efficacy of the perioperative administration of neuraxial clonidine alone or in combination with a local anaesthetic and/or opioids in women having elective Caesarean section under neuraxial anaesthesia when compared with placebo. PubMed, the Cochrane Central Register of Controlled Trials, and EMBASE were searched until February 2017. Eighteen studies were included in the meta-analysis. Neuraxial clonidine reduced 24 h morphine consumption [mean difference (MD): -7.2 mg; 95% confidence interval (CI): -11.4, -3.0 mg; seven studies] and prolonged time to first analgesic request (MD: 135 min; 95% CI: 102, 168 min; 16 studies) when compared with the control group. Neuraxial clonidine increased intraoperative hypotension [odds ratio (OR): 2.849; 95% CI: 1.363, 5.957], intraoperative sedation (OR: 2.355; 95% CI: 1.016, 5.459), but reduced the need for intraoperative analgesic supplementation (OR: 0.224; 95% CI: 0.076, 0.663). The effect of clonidine on intraoperative bradycardia, intraoperative and postoperative nausea and vomiting, postoperative sedation, and pruritus were inconclusive. Neuraxial clonidine did not negatively impact neonatal umbilical artery pH or Apgar scores. This review demonstrates that neuraxial clonidine enhances postoperative analgesia in women having Caesarean section with neuraxial anaesthesia, but this has to be balanced against increased maternal adverse effects.

Effect of ephedrine and phenylephrine on brain oxygenation and microcirculation in anaesthetised patients with cerebral tumours: study protocol for a randomised controlled trial

INTRODUCTION

During brain tumour surgery, vasopressor drugs are commonly administered to increase mean arterial blood pressure with the aim of maintaining sufficient cerebral perfusion pressure. Studies of the commonly used vasopressors show that brain oxygen saturation is reduced after phenylephrine administration, but unaltered by ephedrine administration. These findings may be explained by different effects of phenylephrine and ephedrine on the cerebral microcirculation, in particular the capillary transit-time heterogeneity, which determines oxygen extraction efficacy. We hypothesised that phenylephrine is associated with an increase in capillary transit-time heterogeneity and a reduction in cerebral metabolic rate of oxygen compared with ephedrine. Using MRI and positron emission tomography (PET) as measurements in anaesthetised patients with brain tumours, this study will examine whether phenylephrine administration elevates capillary transit-time heterogeneity more than ephedrine, thereby reducing brain oxygenation.

METHODS AND ANALYSIS

This is a double-blind, randomised clinical trial including 48 patients scheduled for surgical brain tumour removal. Prior to imaging and surgery, anaesthetised patients will be randomised to receive either phenylephrine or ephedrine infusion until mean arterial blood pressure increases to above 60 mm Hg or 20% above baseline. Twenty-four patients were allocated to MRI and another 24 patients to PET examination. MRI measurements include cerebral blood flow, capillary transit-time heterogeneity, cerebral blood volume, blood mean transit time, and calculated oxygen extraction fraction and cerebral metabolic rate of oxygen for negligible tissue oxygen extraction. PET measurements include cerebral metabolic rate of oxygen, cerebral blood flow and oxygen extraction fraction. Surgery is initiated after MRI/PET measurements and subdural intracranial pressure is measured.

ETHICS AND DISSEMINATION

This study was approved by the Central Denmark Region Committee on Health Research Ethics (12 June 2015; 1-10-72-116-15). Results will be disseminated via peer-reviewed publication and presentation at international conferences.

TRIAL REGISTRATION NUMBER

NCT02713087; Pre-results. 2015-001359-60; Pre-results.

Effect of co-administration of different doses of phenylephrine with oxytocin on the prevention of oxytocin-induced hypotension in caesarean section under spinal anaesthesia: A randomised comparative study

INTRODUCTION

Co-administration of phenylephrine prevents oxytocin-induced hypotension during caesarean section under spinal anaesthesia (SA), but higher doses cause reflex bradycardia. This study compares the effects of co-administration of two different doses of phenylephrine on oxytocin-induced hypotension during caesarean section under SA.

METHODS

In this prospective, double-blind study, 90 parturients belonging to the American Society of Anesthesiologists' physical status 1 or 2, undergoing caesarean section under SA were randomised into Group A: oxytocin 3U and phenylephrine 50 μg, Group B: oxytocin 3U and phenylephrine 75 μg, Group C: oxytocin 3U and normal saline, administered intravenously over 5 min after baby extraction. The incidence of hypotension (the primary outcome), rescue vasopressor requirement and side effects were recorded. Statistical analyses were with analysis of variance, Kruskal-Wallis, chi-square and Fisher's exact tests.

RESULTS

Demographic parameters such as age, height, weight, level of sensory block at 20 min and duration of surgery were comparable in all the groups. The incidence of hypotension (Group A - 90%, Group B - 10%, Group C - 98%, P = 0.001), magnitude of fall in mean arterial pressure (Group A-15.03 ± 6.12 mm of Hg, Group B - 6.63 ± 4.49 mm of Hg and Group C-13.03 ± 3.39 mm of Hg, P < 0.001) and rescue vasopressor requirement (Group A-45 ± 15.25 mg, Group B-5 ± 15.25, Group C-91.66 ± 26.53, P < 0.001) were significantly lower in Group B compared to A and C.

CONCLUSION

Co-administration of phenylephrine 75 μg with oxytocin 3U reduces the incidence of oxytocin-induced hypotension compared to phenylephrine 50 μg with oxytocin 3U during caesarean section under spinal anaesthesia.

Maternal cardiac output response to colloid preload and vasopressor therapy during spinal anaesthesia for caesarean section in patients with severe pre-eclampsia: a randomised, controlled trial

We examined the haemodynamic effects of colloid preload, and phenylephrine and ephedrine administered for spinal hypotension, during caesarean section in 42 women with severe early onset pre-eclampsia. Twenty patients with pre-delivery spinal hypotension were randomly allocated to receive an initial dose of either 50 μg phenylephrine or 7.5 mg ephedrine; the primary outcome was percentage change in cardiac index. After a 300-ml colloid preload, mean (SD) cardiac index increased from 4.9 (1.1) to 5.6 (1.2) l.min^-1 .m^-2 (p < 0.01), resulting from an increase in both heart rate, from 81.3 (17.2) to 86.3 (16.5) beats.min^-1 (p = 0.2), and stroke volume, from 111.8 (19.0) to 119.8 (17.9) ml (p = 0.049). Fourteen (33%) and 23 (54.8%) patients exhibited a stroke volume response > 10% and > 5%, respectively; a significant negative correlation was found between heart rate and stroke volume changes. Spinal hypotension in 20 patients was associated with an increase from baseline in cardiac index of 0.6 l.min^-1 .m^-2 (mean difference 11.5%; p < 0.0001). After a median [range] dose of 50 [50-150] μg phenylephrine or 15 [7.5-37.5] mg ephedrine, the percentage change in cardiac index during the measurement period of 150 s was greater, and negative, in patients receiving phenylephrine vs. ephedrine, at -12.0 (7.3)% vs. 2.6 (6.0)%, respectively (p = 0.0001). The percentage change in heart rate after vasopressor was higher in patients receiving phenylephrine, at -9.1 (3.4)% vs. 5.3 (12.6)% (p = 0.0027), as was the change in systemic vascular resistance, at 22.3 (7.5) vs. -1.9 (10.5)% (p < 0.0001). Phenylephrine effectively reverses spinal anaesthesia-induced haemodynamic changes in severe pre-eclampsia, if left ventricular systolic function is preserved.

Techniques for preventing hypotension during spinal anaesthesia for caesarean section

BACKGROUND

Maternal hypotension is the most frequent complication of spinal anaesthesia for caesarean section. It can be associated with nausea or vomiting and may pose serious risks to the mother (unconsciousness, pulmonary aspiration) and baby (hypoxia, acidosis, neurological injury).

OBJECTIVES

To assess the effects of prophylactic interventions for hypotension following spinal anaesthesia for caesarean section.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (9 August 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials, including full texts and abstracts, comparing interventions to prevent hypotension with placebo or alternative treatment in women having spinal anaesthesia for caesarean section. We excluded studies if hypotension was not an outcome measure.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study quality and extracted data from eligible studies. We report 'Summary of findings' tables using GRADE.

MAIN RESULTS

We included 126 studies involving 9565 participants. Interventions were to prevent maternal hypotension following spinal anaesthesia only, and we excluded any interventions considered active treatment. All the included studies reported the review's primary outcome. Across 49 comparisons, we identified three intervention groups: intravenous fluids, pharmacological interventions, and physical interventions. Authors reported no serious adverse effects with any of the interventions investigated. Most trials reported hypotension requiring intervention and Apgar score of less than 8 at five minutes as the only outcomes. None of the trials included in the comparisons we describe reported admission to neonatal intensive care unit. Crystalloid versus control (no fluids)Fewer women experienced hypotension in the crystalloid group compared with no fluids (average risk ratio (RR) 0.84, 95% confidence interval (CI) 0.72 to 0.98; 370 women; 5 studies; low-quality evidence). There was no clear difference between groups in numbers of women with nausea and vomiting (average RR 0.19, 95% CI 0.01 to 3.91; 1 study; 69 women; very low-quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (60 babies, low-quality evidence). Colloid versus crystalloidFewer women experienced hypotension in the colloid group compared with the crystalloid group (average RR 0.68, 95% CI 0.58 to 0.80; 2105 women; 28 studies; very low-quality evidence). There were no clear differences between groups for maternal hypertension requiring intervention (average RR 0.64, 95% CI 0.09 to 4.46, 3 studies, 327 women;very low-quality evidence), maternal bradycardia requiring intervention (average RR 0.99, 95% CI 0.55 to 1.79, 6 studies, 509 women; very low-quality evidence), nausea and/or vomiting (average RR 0.83, 95% CI 0.61 to 1.13, 15 studies, 1154 women, I² = 37%; very low-quality evidence), neonatal acidosis (average RR 0.83, 95% CI 0.15 to 4.52, 6 studies, 678 babies; very low-quality evidence), or Apgar score of less than 8 at five minutes (average RR 0.24, 95% CI 0.03 to 2.05, 11 studies, 826 babies; very low-quality evidence). Ephedrine versus phenylephrineThere were no clear differences between ephedrine and phenylephrine groups for preventing maternal hypotension (average RR 0.92, 95% CI 0.71 to 1.18; 401 women; 8 studies; very low-quality evidence) or hypertension (average RR 1.72, 95% CI 0.71 to 4.16, 2 studies, 118 women, low-quality evidence). Rates of bradycardia were lower in the ephedrine group (average RR 0.37, 95% CI 0.21 to 0.64, 5 studies, 304 women, low-quality evidence). There was no clear difference in the number of women with nausea and/or vomiting (average RR 0.76, 95% CI 0.39 to 1.49, 4 studies, 204 women, I² = 37%, very low-quality evidence), or babies with neonatal acidosis (average RR 0.89, 95% CI 0.07 to 12.00, 3 studies, 175 babies, low-quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (321 babies; low-quality evidence). Ondansetron versus controlOndansetron administration was more effective than control (placebo saline) for preventing hypotension requiring treatment (average RR 0.67, 95% CI 0.54 to 0.83; 740 women, 8 studies, low-quality evidence), bradycardia requiring treatment (average RR 0.49, 95% CI 0.28 to 0.87; 740 women, 8 studies, low-quality evidence), and nausea and/or vomiting (average RR 0.35, 95% CI 0.24 to 0.51; 653 women, 7 studies, low-quality evidence). There was no clear difference between the groups in rates of neonatal acidosis (average RR 0.48, 95% CI 0.05 to 5.09; 134 babies; 2 studies, low-quality evidence) or Apgar scores of less than 8 at five minutes (284 babies, low-quality evidence). Lower limb compression versus controlLower limb compression was more effective than control for preventing hypotension (average RR 0.61, 95% CI 0.47 to 0.78, 11 studies, 705 women, I² = 65%, very low-quality evidence). There was no clear difference between the groups in rates of bradycardia (RR 0.63, 95% CI 0.11 to 3.56, 1 study, 74 women, very low-quality evidence) or nausea and/or vomiting (average RR 0.42 , 95% CI 0.14 to 1.27, 4 studies, 276 women, I² = 32%, very-low quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (130 babies, very low-quality evidence). Walking versus lyingThere was no clear difference between the groups for women with hypotension requiring treatment (RR 0.71, 95% CI 0.41 to 1.21, 1 study, 37 women, very low-quality evidence).Many included studies reported little to no information that would allow an assessment of their risk of bias, limiting our ability to draw meaningful conclusions. GRADE assessments of the quality of evidence ranged from very low to low. We downgraded evidence for limitations in study design, imprecision, and indirectness; most studies assessed only women scheduled for elective caesarean sections.External validity also needs consideration. Readers should question the use of colloids in this context given the serious potential side effects such as allergy and renal failure associated with their administration.

AUTHORS' CONCLUSIONS

While interventions such as crystalloids, colloids, ephedrine, phenylephrine, ondansetron, or lower leg compression can reduce the incidence of hypotension, none have been shown to eliminate the need to treat maternal hypotension in some women. We cannot draw any conclusions regarding rare adverse effects associated with use of the interventions (for example colloids) due to the relatively small numbers of women studied.

The Influence of Body Mass Index on Sensorimotor Block and Vasopressor Requirement During Spinal Anesthesia for Elective Cesarean Delivery

BACKGROUND

It has been suggested that the dose requirement for spinal anesthesia (SA) is lower in obese patients for cesarean delivery (CD). In this prospective, observational, noninferiority study, we tested the hypothesis that obesity would not have a clinically important effect on vasopressor requirements or block height.

METHODS

Two groups of 25 parturients, group O (body mass index [BMI] >40 kg/m) and group N (BMI <32 kg/m) requiring elective CD were recruited. All patients received 10 mg intrathecal hyperbaric bupivacaine coadministered with 10 μg fentanyl. Dermatomal levels were assessed at 5 and 25 minutes after SA, and at completion of surgery, using light touch and cold sensation in response to ethyl chloride. The primary outcomes were phenylephrine requirement in the first 30 minutes after SA, and maximum block height, measured by the sensation of touch and cold. Secondary outcomes were total phenylephrine dose required, changes in hand grip strength, and peak flow rate.

RESULTS

There were no significant between-group differences in median block height as assessed by touch at 5 or 25 minutes or by temperature at 5 minutes. At 25 minutes, there was a 2-dermatome difference in median block height for loss of temperature sensation between group O and group N (T2 vs T4, 95% confidence interval [CI] of the difference in medians 0-2 dermatomes). No blocks extended to cervical dermatomes. The median (range) phenylephrine dose for the first 30 minutes was 150 µg (0-900 µg), and 100 µg (0-1250 µg) in group N and group O, respectively. The 95% CI for the difference between the 2 median doses was -150 µg to 100 µg. There were no differences in median percentage reductions in peak flow rate or median hand grip strength after SA. Mean surgical time was longer in group O than in group N (49.1 vs 39.4 min, 95% CI difference 1.7-17.7 min). The mean time for recovery of touch sensation to T10 was longer in group O (152 vs 132 min, 95% CI difference 3.8-36.2 min). No analgesic supplementation was required.

CONCLUSION

Only a minor increase in block height as assessed by temperature occurred in group O at 25 minutes. Vasopressor requirements during the first 30 minutes of SA were equivalent. Time for regression of SA block level was longer in the group O, which may be beneficial considering the longer surgical time. A dose of spinal bupivacaine 10 mg for single-shot SA should not be reduced in morbidly obese parturients.