Retrospective analysis of anesthetic interventions for obese patients undergoing elective cesarean delivery

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

PURPOSE

To determine the 90% effective dose (ED90) of intrathecal hyperbaric bupivacaine for Cesarean delivery under combined spinal-epidural anesthesia (CSE) in parturients with super obesity (body mass index [BMI] ≥ 50 kg·m-2).

METHODS

We enrolled parturients with BMI ≥ 50 kg·m-2 with term, singleton vertex pregnancies undergoing elective Cesarean delivery under CSE. An independent statistician generated the 0.75% hyperbaric bupivacaine dosing regimen in increments of 0.75 mg using a biased-coin up-down sequential allocation technique. This was combined with 15 μg fentanyl, 150 μg morphine, and normal saline to a volume of 2.05 mL. The initial and maximum doses were 9.75 mg and 12 mg, respectively. Participants, clinical team, and outcome assessors were blinded to the dose. The primary outcome was block success, defined as T6 block to pinprick within ten minutes and no intraoperative analgesic supplementation within 90 min of spinal injection. We determined the ED90 using logistic regression.

RESULTS

We enrolled 45 parturients and included 42 in the analysis. All doses achieved a T6 level within ten minutes, and the primary outcome occurred in 0/1 (0%) of the 9.75-mg doses, 2/3 (67%) of the 10.5-mg doses, 21/27 (78%) of the 11.25-mg doses, and 11/11 (100%) of the 12-mg doses. The ED90 of hyperbaric bupivacaine was 11.56 mg (95% confidence interval, 11.16 to 11.99). Four parturients (9.5%) had sensory level higher than T2, but none was symptomatic or required general anesthesia.

CONCLUSION

The estimated ED90 of hyperbaric bupivacaine with fentanyl and morphine in parturients with super obesity undergoing Cesarean delivery under CSE was approximately 11.5 mg.

STUDY REGISTRATION

ClinicalTrials.gov (NCT03781388); first submitted 18 December 2018.

Anesthesia and Analgesia for the Obese Parturient

Obesity is a worldwide epidemic and is associated with an increased risk of hypertension, diabetes, and obstructive sleep apnea. Pregnant patients with obesity experience a higher risk of maternal and fetal complications. Anesthesia also poses higher risks for obese parturients and may be more technically challenging due to body habitus. Safe anesthesia practice for these patients must take into consideration the unique challenges associated with the combination of pregnancy and obesity.

Effect of Intravenous Ketamine on Hypocranial Pressure Symptoms in Patients with Spinal Anesthetic Cesarean Sections: A Systematic Review and Meta-Analysis

BACKGROUND

Pregnant women are more likely to suffer post-puncture symptoms such as headaches and nausea due to the outflow of cerebrospinal fluid after spinal anesthesia. Because ketamine has the effect of raising intracranial pressure, it may be able to improve the symptoms of perioperative hypocranial pressure and effectively prevent the occurrence of hypocranial pressure-related side effects.

METHOD

Keywords such as ketamine, cesarean section, and spinal anesthesia were searched in databases including Medline, Embase, Web of Science, and Cochrane from 1976 to 2021. Thirteen randomized controlled trials were selected for the meta-analysis.

RESULTS

A total of 12 randomized trials involving 2099 participants fulfilled the inclusion criteria. There was no significant association between ketamine and the risk of headaches compared to the placebo (RR = 1.12; 95% CI: 0.53, 2.35; p = 0.77; I² = 62%). There was no significant association between ketamine and nausea compared to the placebo (RR = 0.66; 95% CI: 0.40, 1.09; p = 0.10; I² = 57%). No significant associations between ketamine or the placebo and vomiting were found (RR = 0.94; 95% CI: 0.53, 1.67; p = 0.83; I² = 72%).

CONCLUSION

Intravenous ketamine does not improve the symptoms caused by low intracranial pressure after spinal anesthesia in patients undergoing cesarean section.

Obesity And Obstetric Anesthesia: Current Insights

Obesity is a significant global health problem. It results in a higher incidence of complications for pregnant women and their neonates. Cesarean deliveries are more common in obese parturients as well. The increased burden of comorbidities seen in this population, such as obstructive sleep apnea, necessitates antepartum anesthetic consultation. These patients pose unique challenges for the practicing anesthesiologist and may benefit from optimization prior to delivery. Complications from anesthesia and overall morbidity and mortality are higher in this population. Neuraxial anesthesia can be challenging to place in the obese parturient, but is the preferred anesthetic for cesarean delivery to avoid airway manipulation, minimize aspiration risk, prevent fetal exposure to volatile anesthetic, and decrease risk of post-partum hemorrhage from volatile anesthetic exposure. Monitoring and positioning of these patients for surgery may pose specific challenges. Functional labor epidural catheters can be topped up to provide conditions suitable for surgery. In the absence of a working epidural catheter, a combined spinal epidural anesthetic is often the technique of choice due to relative ease of placement versus a single shot spinal technique as well as the ability to extend the anesthetic through the epidural portion. For cesarean delivery with a vertical supraumbilical skin incision, a two-catheter technique may be beneficial. Concern for thromboembolism necessitates early mobilization and a multimodal analgesic regimen can help accomplish this. In addition, thromboprophylaxis is recommended in this population after delivery—especially cesarean delivery. These patients also need close monitoring in the post-partum period when they are at increased risk for several complications.

A study of factors influencing surgical cesarean delivery times in an academic tertiary center

BACKGROUND

Knowledge of hospital-specific average cesarean delivery operative times, and factors influencing length of surgery, can serve as a guide for anesthesiologists when choosing the optimal anesthetic technique. The aim of this study was to determine operative times and the factors influencing those times for cesarean delivery.

METHODS

We conducted a retrospective review of all 1348 cesarean deliveries performed at an academic hospital in 2011. The primary outcome was mean operative time for first, second, third and fourth or more cesarean deliveries. The secondary goal was to identify factors influencing operative time. Variables included age, body mass index, previous surgery, gestational age, urgency of cesarean delivery, anesthesia type, surgeon's seniority, layers closed, and performance of tubal ligation.

RESULTS

Mean (standard deviation) operative times for first (n=857), second (n=353), third (n=108) and fourth or more (n=30) cesarean deliveries were 56 (19), 60 (19), 69 (28) and 82 (31) minutes, respectively (P <0.0001, all groups different). Emergency status of the case and later gestational age were associated with shorter operative times. Higher body mass index, a less senior surgeon, the number of layers closed, and tubal ligation, increased operative times. These factors accounted for 18% of the variability.

CONCLUSIONS

Third and fourth cesarean delivery or the presence of other factors that could increase operative time may warrant catheter-based anesthetic techniques or the addition of adjunctive medications to prolong spinal anesthetic block. Institutional and individual surgeon factors may play an even more important role in determining surgical time.

Associations between maternal size and health outcomes for women undergoing caesarean section: a multicentre prospective observational study (The MUM SIZE Study)

OBJECTIVES

To investigate associations between maternal body mass index (BMI) at delivery (using pregnancy-specific BMI cut-off values 5 kg/m² higher in each of the WHO groups) and clinical, theatre utilisation and health economic outcomes for women undergoing caesarean section (CS).

DESIGN

A prospective multicentre observational study.

SETTING

Seven secondary or tertiary referral obstetric hospitals.

PARTICIPANTS

One thousand and four hundred and fifty-seven women undergoing all categories of CS.

DATA COLLECTION

Height and weight were recorded at the initial antenatal visit and at delivery. We analysed the associations between delivery BMI (continuous and pregnancy-specific cut-off values) and total theatre time, surgical time, anaesthesia time, maternal and neonatal adverse outcomes, total hospital admission and theatre costs.

RESULTS

Mean participant characteristics were: age 32 years, gestation at delivery 38.4 weeks and delivery BMI 32.2 kg/m². Fifty-five per cent of participants were overweight, obese or super-obese using delivery pregnancy-specific BMI cut-off values. As BMI increased, total theatre time, surgical time and anaesthesia time increased. Super-obese participants had approximately 27% (17 min, p<0.001) longer total theatre time, 20% (9 min, p<0.001), longer surgical time and 40% (11 min, p<0.001) longer anaesthesia time when compared with normal BMI participants. Increased BMI at delivery was associated with increased risk of maternal intensive care unit admission (relative risk 1.07, p=0.045), but no increased risk of neonatal admission to higher acuity care. Total hospital admission costs were 15% higher in super-obese women compared with normal BMI women and theatre costs were 27% higher in super-obese women.

CONCLUSIONS

Increased maternal BMI was associated with increased total theatre time, surgical and anaesthesia time, increased total hospital admission costs and theatre costs. Clinicians and health administrators should consider these clinical risks, time implications and financial costs when managing pregnant women.

Anesthetic Considerations in the Obese Parturient

The provision of anesthesia to the morbidly obese parturient is technically challenging. The anesthesia provider anticipates difficulty with intravenous access, positioning, monitoring, and placement of neuraxial anesthesia. There is a higher incidence of hypotension in obese parturients during neuraxial anesthesia most likely due to concealed aortocaval compression as positioning these patients is difficult. Most providers will provide either epidural or combined spinal/epidural anesthesia for cesarean delivery due to the variable duration of the surgical procedure. Among obese gravidas, there is a lower risk of the development of a headache from an accidental dural puncture, due not to the body habitus, but rather to the group's higher cesarean delivery rate. It is the process of bearing down during delivery that increases the chance of the development of a headache following dural puncture.

Managing anesthesia for cesarean section in obese patients: current perspectives

Obesity is a worldwide epidemic. It is associated with increased comorbidities and increased maternal, fetal, and neonatal complications. The risk of cesarean delivery is also increased in obese parturients. Anesthetic management of the obese parturient is challenging and requires adequate planning. Therefore, those patients should be referred to antenatal anesthetic consultation. Anesthesia-related complications and maternal mortality are increased in this patient population. The risk of difficult intubation is increased in obese patients. Neuraxial techniques are the preferred anesthetic techniques for cesarean delivery in obese parturients but can be technically challenging. An existing labor epidural catheter can be topped up for cesarean delivery. In patients who do not have a well-functioning labor epidural, a combined spinal epidural technique might be preferred over a single-shot spinal technique since it is technically easier in obese parturients and allows for extending the duration of the block as required. A continuous spinal technique can also be considered. Studies suggest that there is no need to reduce the dose of spinal bupivacaine in the obese parturient, but there is little data about spinal dosing in super obese parturients. Intraoperatively, patients should be placed in a ramped position, with close monitoring of ventilation and hemodynamic status. Adequate postoperative analgesia is crucial to allow for early mobilization. This can be achieved using a multimodal regimen incorporating neuraxial morphine (with appropriate observations) with scheduled nonsteroidal anti-inflammatory drugs and acetaminophen. Thromboprophylaxis is also important in this patient population due to the increased risk of thromboembolic complications. These patients should be monitored carefully in the postoperative period, since there is increased risk of postoperative complications in the morbidly obese parturients.

Pregnancy risks associated with obesity

Obesity has increased dramatically in the United States over the last several decades, with approximately 40% of pregnant women now considered overweight or obese. Obesity has been shown to be associated with numerous poor pregnancy outcomes, including increased rates of preeclampsia, gestational diabetes, fetal macrosomia, stillbirth, postterm pregnancy, and increased rates of cesarean delivery. Many of these complications have been found to increase even further with increasing body mass index in a dose-response fashion. In this review, the association of obesity with maternal, fetal, and pregnancy outcomes is discussed as are the recommendations for caring for the obese gravida.

Body mass index and operative times at cesarean delivery

OBJECTIVE

To examine the relationship between body mass index (BMI, kg/m) and incision-to-delivery interval and total operative time at cesarean delivery.

METHODS

Women with singleton gestations undergoing uncomplicated primary and repeat cesarean deliveries were identified from the Maternal-Fetal Medicine Units Network Cesarean Registry. Women were classified by BMI category at time of delivery (normal 18.5-24.9, overweight 25.0-29.9, obese 30.0-39.9, and morbidly obese 40 or greater). Incision-to-delivery interval and total operative times during cesarean delivery were compared among the three groups. Primary outcome was prolonged incision-to-delivery interval as defined by 90th percentile or greater of the study population or 18 minutes or longer.

RESULTS

Of the 21,372 women included in the analysis, 9,928 were obese (46.5%) and 2,988 (14.0%) were morbidly obese. Longer operative times were found among women with overweight (median [interquartile range] incision-to-delivery: 9.0 [6.0] and total operative time: 45.0 [21.0] minutes), obese (10.0 [7.0]; 48.0 [22.0] minutes), and morbidly obese BMIs (12.0 [8.0]; 55.0 [26.0] minutes) compared with women with normal BMI at delivery (9.0 [5.0]; 43.0 [20.0] minutes) (P<.001). Morbidly obese women had a more frequent incision-to-delivery interval that was 18 minutes or longer (n=602 [20%] compared with 127 [6%] in normal BMI). After adjustments including number of prior cesarean deliveries, incision-to-delivery interval 18 minutes or longer was significantly related to obese (odds ratio [OR] 1.62, 95% confidence interval [CI] 1.31-2.03) and morbidly obese (OR 2.81, 95% CI 2.24-3.56) BMI at delivery.

CONCLUSION

Increasing BMI is related to increased incision-to-delivery interval and total operative time at cesarean delivery with morbidly obese BMI exposing women to the highest risk of prolonged incision-to-delivery interval.

LEVEL OF EVIDENCE

: II.

A randomized controlled comparison between combined spinal-epidural and single-shot spinal techniques in morbidly obese parturients undergoing cesarean delivery: time for initiation of anesthesia

BACKGROUND

There is no current consensus on the optimal technique for subarachnoid anesthesia in morbidly obese parturients even though some providers prefer the combined spinal-epidural (CSE) over single-shot spinal (SSS) technique. In this randomized controlled study, we compared the time required for initiation of subarachnoid anesthesia between SSS and CSE techniques in morbidly obese parturients undergoing elective cesarean delivery.

METHODS

Morbidly obese parturients presenting for elective cesarean delivery were randomized to receive subarachnoid anesthesia performed either with a SSS or a CSE technique. The spinal procedure in the sitting position was attempted by an experienced resident for up to 10 minutes, and if unsuccessful, the attending obstetric anesthesiologist assumed control of the procedure. The primary outcome was the time it took from the insertion of the introducer needle (SSS group) or insertion of the epidural needle (CSE group) to the end of intrathecal injection of drugs (procedure time).

RESULTS

Forty-four patients were enrolled and completed the study. Three were excluded due to protocol violations. Of the remaining, 21 patients were in the SSS group and 20 in the CSE group. Demographic variables and mean (SD) body mass index (48.7 ± 7.6 kg/m for SSS; 49.9 ± 8.6 kg/m for CSE) were not different between groups. The median [interquartile range] for procedure time was 210 [116-692] seconds and 180 [75-450] seconds for SSS and CSE groups, respectively (P = 0.36), while the 95% confidence interval (CI) of the difference was -80 to +180 seconds. The first operator completed the procedure in <10 minutes in 71% of subjects in the SSS group and 95% of those in the CSE group (P = 0.09) and the 95% CI of the difference was -2% to +45%. There were more attempts to successful completion of the procedure in the SSS group (P = 0.007) with its 95% CI of the difference being +1 to +6.

CONCLUSION

Our results suggest that the CSE technique is noninferior to the SS technique in morbidly obese parturients for time of initiation of subarachnoid anesthesia and may be accomplished with fewer attempts than the SSS technique with experienced residents.

Obesity in pregnancy: a big problem and getting bigger

Obesity has increased dramatically in the United States over the last several decades, with approximately 40% of women now considered overweight or obese. Obesity has been shown to be associated with poor pregnancy outcomes, including increased rates of cesarean delivery, preeclampsia, gestational diabetes, fetal macrosomia, stillbirth, and postterm pregnancy. In this review, we discuss the association of obesity with maternal, fetal, and pregnancy outcomes as well as the recommendations for care of the obese gravida.

TARGET AUDIENCE

Obstetricians and gynecologists and family physicians.

LEARNING OBJECTIVES

After completing the CME activity, physicians should be better able to describe the maternal, neonatal, and intrapartum complications associated with obesity in pregnancy and implement additional changes to prenatal care appropriate for the obese gravida.

Predictors of failed trial of labor among women with an extremely obese body mass index

OBJECTIVE

The purpose of this study was to examine predictors associated with cesarean delivery (CD) among extremely obese women undergoing a trial of labor (TOL).

STUDY DESIGN

Using a delivery database, we identified all pregnant women delivering at our institution from Jan. 1, 2008, through July 31, 2010, weighing >275 lb at the time of delivery who attempted a TOL with a singleton gestation >34 weeks' gestation. Demographic and obstetrical factors were compared for those having a successful vaginal delivery to those having a CD.

RESULTS

During the study period, there were 357 pregnant women who weighed >275 lb (all with body mass index [BMI] >40 kg/m(2)), and among these, 248 (69.5%) attempted a TOL. Women having a CD had a greater BMI (51.6 vs 49.9 kg/m(2), P = .038), were less likely to be parous (32.2% vs 65.8%, P < .0001), and were more likely to be induced (80.5% vs 57.8%) compared to those having a vaginal delivery. Using a multivariable logistic regression model, among nulliparous women, maternal age, parity, and cervical dilation at time of admission were independent predictors for CD. Furthermore, an increase in BMI of 10 kg/m(2) was associated with a 3.5 increased odds (P = .002) for CD.

CONCLUSION

Among nulliparous extremely obese women attempting a TOL, BMI was an independent predictor of CD, with the rate of CD increasing further with increasing BMI. The underlying mechanisms for failed TOL in the setting of maternal obesity remain largely unknown.

Epidural catheter placement in morbidly obese parturients with the use of an epidural depth equation prior to ultrasound visualization

Background. Previously, Balki determined the Pearson correlation coefficient with the use of ultrasound (US) was 0.85 in morbidly obese parturients. We aimed to determine if the use of the epidural depth equation (EDE) in conjunction with US can provide better clinical correlation in estimating the distance from the skin to the epidural space in morbidly obese parturients. Methods. One hundred sixty morbidly obese (≥40 kg/m²) parturients requesting labor epidural analgesia were enrolled. Before epidural catheter placement, EDE was used to estimate depth to the epidural space. This estimation was used to help visualize the epidural space with the transverse and midline longitudinal US views and to measure depth to epidural space. The measured epidural depth was made available to the resident trainee before needle insertion. Actual needle depth (ND) to the epidural space was recorded. Results. Pearson's correlation coefficients comparing actual (ND) versus US estimated depth to the epidural space in the longitudinal median and transverse planes were 0.905 (95% CI: 0.873 to 0.929) and 0.899 (95% CI: 0.865 to 0.925), respectively. Conclusion. Use of the epidural depth equation (EDE) in conjunction with the longitudinal and transverse US views results in better clinical correlation than with the use of US alone.

Anesthesia considerations in the obese gravida

Obesity is associated with serious morbidity during pregnancy, and obese women also are at a high risk of developing complications during labor, leading to an increased risk for instrumental and Cesarean deliveries. The engagement of the obstetrical anesthetist in the management of this group of high-risk patients should be performed antenatally so that an appropriate management strategy can be planned in advance to prevent an adverse outcome. Good communication between all care providers is essential. The obese patient in labor should be encouraged to have a functioning epidural catheter placed early in labor. Apart from providing analgesia and alleviating physiological derangements during labor, the presence of a functioning epidural catheter can also be used to induce anesthesia quickly in the event of an emergency cesarean section, thus avoiding a general anesthesia, which has exceedingly high risks in the obese parturient. Successful management of the obese patient necessitates a comprehensive strategy that encompasses a multidisciplinary and holistic approach from all care-providers.