The impact of body mass index on the risk of high spinal block in parturients undergoing cesarean delivery: a retrospective cohort study

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.

Comparison of perioperative outcomes and anesthetic-related complications of morbidly obese and super-obese parturients delivering by cesarean section

OBJECTIVE

To compare the perioperative outcomes and anesthetic-related complications of morbidly obese and super-obese parturients delivering by cesarean section.

METHODS

A retrospective analysis of 6 years of data was performed. Exclusions were cases with gestational ages <24 weeks, placenta accreta spectrum, polyhydramnios, or multiple gestations.

RESULTS

The study included 494 patients whose body mass index (BMI) exceeded 40 kg/m² at delivery. Of these, 469 were morbidly obese (BMI 40-49.9; mean, 42.9 ± 2.4), and 25 were super obese (BMI >50; mean, 54.5 ± 4.2). Twenty-four (5.1%) morbidly obese women received general anesthesia. The other 445 patients (94.9%) in the morbid obesity group underwent cesarean delivery under regional anesthesia; however, some (2.2%; 10/445) received general anesthesia after regional anesthesia failed. In the super-obesity group, 23 patients (92.0%) received regional anesthesia, while two patients (8.0%) received general anesthesia. There were no cases of pulmonary aspiration, maternal deaths, or difficult or failed intubation. There was one episode of cardiac arrest in a patient with a BMI of 47.9. Among the morbidly obese and super-obese women given regional anesthesia, the super-obese patients had significantly greater volumes of ephedrine and norepinephrine consumption (p = 0.027 and 0.030), intravenous fluids (p = 0.006), and bleeding during surgery (p = 0.017). They also had more hypotensive episodes (p = 0.038). The two groups' incidences of neonatal birth asphyxia, postpartum hemorrhage, blood transfusion, and uterine atony did not differ significantly. The lengths of stay in the hospital were also comparable.

CONCLUSIONS

Among the women receiving regional anesthesia, the super-obese parturients had greater intraoperative bleeding, a higher proportion of hypotensive episodes, and a greater vasopressor requirement than the morbidly obese parturients. Anesthesiologists must prepare for the adverse perioperative events that such women risk experiencing during a delivery by cesarean section.

www.clinicaltrials.gov ID: NCT04657692.

Spinal anesthesia in elective lumbar spinal surgery

Spinal anesthesia (SA) is gaining recognition as a safe and efficacious regional alternative to general anesthesia for elective lumbar surgery. However, unfamiliarity with management issues related to its use has limited the adoption of awake spine surgery, despite its benefits. Few centers in the United States routinely offer SA for elective lumbar surgery, and a comprehensive workflow to standardize SA for lumbar surgery is lacking. In this article, we examine recent literature on the use of SA in lumbar surgery, review the experience of our institution with SA in lumbar surgery, and provide a cohesive outline to streamline the implementation of SA from the perspective of the anesthesiologist. We review the critical features of SA in contemporary lumbar surgery, including selection of patients, methods of SA, intraoperative sedation, and management of several important technical considerations. We aimed to flatten the learning curve to improve the availability and accessibility of the technique for eligible patients.

A Height-Based Dosing Algorithm of Bupivacaine in Spinal Anesthesia for Decreasing Maternal Hypotension in Cesarean Section Without Prophylactic Fluid Preloading and Vasopressors: A Randomized-Controlled Non-Inferiority Trial

Background

There is a high incidence of maternal hypotension in spinal anesthesia for cesarean section. The aim of the study is to investigate whether there is a height-based dosing algorithm of bupivacaine that provides adequate anesthesia with less maternal hypotension.

Methods

There were 2 groups of 280 parturients who did not receive prophylactic fluid preloading: Test and Conventional group. In Test group, a height based dosing algorithm was used to confirm the dose of bupivacaine in parturients without prophylactic vasopressors. In the Conventional group, a constant dose of bupivacaine was used. The complications and quality of anesthesia were evaluated.

Results

In the Conventional group, the shorter participants had higher incidence of hypotension, faster sensory block time, and more participants with complete motor block (p = 0.030, 2.957 × 10^-14, and 0.012). In the Test group, the incidence of hypotension, sensory block time, and number of participants with complete motor block did not change with height (p = 0.199, 0.617, and 0.209). The height-based dosing algorithm of bupivacaine decreased the incidence of hypotension (p = 0.004), induced lower sensory block level and less degree of motor block (p = 3.513 × 10^-7 and 5.711 × 10^-11). The quality of analgesia, quality of muscle relaxation, and degree of intraoperative comfort were similar in both groups (p = 0.065, 0.498, and 0.483).

Conclusions

The height influences the dose of bupivacaine in spinal anesthesia; without prophylactic fluid pre-loading and vasopressors, the height-based dosing algorithm of bupivacaine is suitable, and meets the cesarean section' requirement with less maternal hypotension.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier: NCT03497364.

Effect of maternal body mass index on the prophylactic dose of phenylephrine for preventing hypotension in parturients after spinal anaesthesia

BACKGROUND

To compare the median effective dose (ED₅₀) of phenylephrine for prophylactic continuous infusion in parturients with different body mass indices (BMIs) during combined spinal-epidural anaesthesia for caesarean section and to investigate the impact of maternal BMI on the prophylactic dose of phenylephrine.

METHODS

Parturients receiving combined spinal-epidural anaesthesia for elective caesarean section were divided into a standard group (Group S, BMI < 30 kg/m²) and an obesity group (Group O, BMI > 30 kg/m²), each with 30 patients. A sequential allocation design was used to administer the prophylactic infusion of phenylephrine after the completion of a spinal anaesthetic injection to prevent hypotension (defined as a reduction of systolic blood pressure ≥ 20% of the baseline value or systolic blood pressure < 90 mmHg), with an initial infusion rate of 50 μg/min for the first parturient subsequent adjusted up or down by 10 μg/min depending on whether the previous parturient developed hypotension or not during the study period. The Dixon and Massey method and the isotonic regression method were used to calculate and compare the ED₅₀ and 95% confidence interval (CI) of phenylephrine between the two groups.

RESULTS

The results were 21.92 μg/min (95% CI, 14.90-28.94 μg/min) for Group S and 42.14 μg/min (95% CI, 24.58-59.70 μg/min) for Group O. The ratio of relative potency of Group O to Group S is 1.92 (95% CI 1.09 - 3.14), P = 0.034.

CONCLUSIONS

The dose of phenylephrine for the prevention of hypotension after spinal anaesthesia for caesarean section is dependent on maternal BMI. Therefore, a weight-based phenylephrine dose is reasonable.

The impact of height on the spread of spinal anesthesia and stress response in parturients undergoing caesarean section: a prospective observational study

Background

The spread of spinal anesthesia was influenced by many factors, and the effect of body height on spinal anesthesia is still arguable. This study aimed to explore the impact of height on the spread of spinal anesthesia and the stress response in parturients.

Methods

A total of ninety-seven parturients were allocated into two groups according to their height: the shorter group (body height was shorter than 158 cm) and taller group (body height was taller than 165 cm). Spinal anesthesia was performed with the same amount of 12 mg plain ropivacaine in mothers of different heights. The primary outcome of the study was the success or failure of the spinal anesthesia. The secondary outcomes of the study were stress response, time to T6 sensory level, the incidence of hypotension, the satisfaction of abdominal muscle relaxation and patient VAS scores.

Results

The rate of successful spinal anesthesia in the shorter group was significantly higher than that in the taller group (p = 0.02). The increase of maternal cortisol level in the shorter group was lower than that in the taller group at skin closure (p = 0.001). The incidence of hypotension (p = 0.013), time to T6 sensory block (p = 0.005), the quality of abdominal muscle relaxation (p <  0.001), and VAS values in stretching abdominal muscles and uterine exteriorization (p <  0.001) in the shorter group were significantly different from those in the taller group. Multivariate analysis showed that vertebral column length (p <  0.001), abdominal girth (p = 0.022), amniotic fluid index (p = 0.022) were significantly associated with successful spinal anesthesia.

Conclusions

It’s difficult to use a single factor to predict the spread of spinal anesthesia. Patient’s vertebral column length, amniotic fluid index and abdominal girth were the high determinant factors for predicting the spread of spinal anesthesia.

Trials registration

ChiCTR-ROC-17012030 (Chictr.org.cn), registered on 18/07/2017.

Anatomical dimensions of the lumbar dural sac predict the sensory block level of continuous epidural analgesia during labor

BACKGROUND

The anatomical dimensions of the lumbar dural sac determine the sensory block level of spinal anesthesia; however, whether they show the same predictive value during continuous epidural anesthesia (CEA) remains undetermined. We designed the present study to verify the efficacy of the anatomical dimensions of the lumbar dural sac in predicting the sensory block level during labor analgesia.

METHODS

A total of 122 parturients with singleton pregnancies requesting labor analgesia were included in this study. The lumbar dural sac diameter (DSD), lumbar dural sac length (DSL), lumbar dural sac surface area (DSA), and lumbar dural sac volume (DSV) were measured with an ultrasound color Doppler diagnostic apparatus. CEA was performed at the L2-L3 interspace. After epidural cannulation, an electronic infusion pump containing 0.08% ropivacaine and sufentanil 0.4 μg/ml was connected. The sensory block level was determined with alcohol-soaked cotton, a cotton swab, and a pinprick. The analgesic efficacy of CEA was determined with a visual analog scale (VAS). The parturients were divided into two groups, "ideal analgesia" and "nonideal analgesia," and the groups were compared by t test. Pearson's correlation was performed to evaluate the association between the anatomical dimensions of the lumbar dural sac and sensory block level. Multiple linear regression analysis was used to create a model for predicting the sensory block level.

RESULTS

In the ideal analgesia group, the height, DSL, DSA, DSV and DSD were significantly smaller, and the body mass index (BMI) was significantly larger (P < 0.05). In addition, the DSL demonstrated the strongest correlation with the peak level of pain block (r = - 0.816, P < 0.0001; Fig. 2A), temperature block (r = - 0.874, P < 0.0001; Fig. 3A) and tactile block (r = - 0.727, P < 0.0001; Fig. 4A). Finally, the multiple linear regression analysis revealed that DSL and BMI contributed to predicting the peak sensory block level.

CONCLUSION

In conclusion, our study shows that the sensory block level of CEA is higher when the DSL, DSA, DSV and DSD of puerperae are lower. DSL and BMI can be treated as predictors of the peak sensory block level in CEA during labor analgesia.

Cesarean Delivery in a Patient With Body Mass Index Over 100: Continuous Spinal Anesthesia in Two Consecutive Deliveries

Anesthetic implications for morbidly obese parturients have been well described; however, the literature has not yet clarified whether there are additional or unique concerns if the body mass index (BMI) rises farther above the so-called super morbid obesity level: BMI >50 kg/m². There have only been a few case reports focusing on patients with BMI close to or above 100. Parturients with BMI significantly greater than 50 are uncommon, but they represent an increasing proportion among the morbidly obese. In this report, we present the use of continuous spinal anesthesia in consecutive cesarean deliveries for a patient with a BMI of 102 at her first delivery and 116 at her second. For both deliveries, an intrathecal catheter dosing incrementally provided effective anesthesia with a cumulative dose of hyperbaric bupivacaine 12 mg, fentanyl 15 mcg, and morphine 100 mcg given in 0.25-ml increments over 12 minutes, with 0.25-ml sterile saline flushes between doses. While dosing the catheter, the patient was gradually lowered to a 30° semi-recumbent position for surgery. This strategy minimized the risk of high spinal block or respiratory distress. She did not develop any postdural puncture headache (PDPH). This case report offers an extreme example and provides estimates towards adjusting staffing, equipment, location, timing, positioning, anesthetic technique, and dosing for cesarean deliveries in patients with very high BMI levels.

Obesity decreases the EC50 of epidural ropivacaine when combined with dexmedetomidine for labor analgesia

OBJECTIVES

This study aims to estimate the EC50 of ropivacaine when co-administered with dexmedetomidine for epidural labor analgesia in antepartum obese and non-obese parturients.

METHODS

Sixty parturients scheduled for epidural labor analgesia were enrolled and divided into antepartum obesity (AO) and control (CON) groups, according to their body mass index at labor. Both groups received 0.5 µg/mL dexmedetomidine with ropivacaine as anesthetics. The concentration of ropivacaine was initially set at 0.125% and varied by 0.01% according to the up-and-down rule for sequential allocation. Hemodynamic parameters were monitored and pain intensity was assessed using a visual analog scale.

RESULTS

When co-administered with dexmedetomidine, the EC50 of ropivacaine was 0.095% (95% confidence interval [CI]: 0.090-0.100%) and 0.070% (95% CI: 0.062-0.076%) in CON and AO groups, respectively. There was a significant difference between the two groups (P < 0.001). EC95 values of ropivacaine were 0.084% (95% CI: 0.077-0.122%) and 0.106% (95% CI: 0.101-0.128%) in AO and CON groups, respectively.

CONCLUSION

Patients with antepartum obese may require decreased ropivacaine concentration for epidural labor analgesia when co-administered with 0.5 µg/mL dexmedetomidine.

Obesity in women: anaesthetic implications for peri-operative and peripartum management

The prevalence, healthcare and socio-economic impact of obesity (defined as having a body mass index of ≥ 30 kg.m^-2 ) are disproportionately higher in women than men. A combination of biological and social factors, including the adaptation of energy homeostasis to the increased demands of pregnancy and lactation and poor access to healthy foods or exercise facilities, contribute to the increasing prevalence of obesity in women. Obesity-related physiological changes stem from mass loading and increased metabolism of adipose tissue, as well as secretion of bioactive substances from adipocytes leading to chronic low-grade inflammation. As a result, obesity is associated with increased risks of: infertility; malignancy; sleep-disordered breathing; cardiovascular disease; diabetes; and thromboembolism. Hence, obese women are at markedly increased risk of peri-operative morbidity and mortality and require comprehensive evaluation and targeted comorbidity optimisation by a multidisciplinary team. In addition to routine obstetric challenges, pregnancy in women with obesity further exacerbates the above risks, making multidisciplinary management starting at pre-conception even more important. Weight loss, lifestyle management and optimisation of comorbidity are the cornerstone of reducing obesity-related risks. The anaesthetist plays a vital role within the multidisciplinary team by emphasising weight loss as part of pre-operative comorbidity optimisation, formulation of individualised peri-operative management plans, supervising postoperative care in the high dependency or intensive care settings and providing safe labour analgesia and careful peripartum management for obese parturients.

Pushing the Envelope in Obstetric Care: A Case Report of Cesarean Delivery in a Parturient with a BMI >100 kg m-2

An increasing number of women with a body mass index (BMI) ≥ 60 kg m⁻², referred to as super-super obesity, are requiring anesthetic care for labor and delivery. Management of these patients presents obstetric, anesthetic, and logistical challenges. We report our experience in the management of cesarean delivery in a parturient with a BMI of 112 kg m⁻². Use of epidural anesthesia and performance of a supraumbilical transverse surgical incision with caudal placement of the panniculus resulted in optimal hemodynamic and ventilatory parameters. Effective multidisciplinary planning and communication is key. We present this case to highlight decision-making strategies and elucidate our approach in the management of this complex obstetric case.

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.

Impact of Epidural Versus General Anesthesia on Major Lumbar Surgery in Elderly Patients

STUDY DESIGN

This was a retrospective comparative study.

OBJECTIVE

The main objective of this study was to investigate the effects of epidural anesthesia (EA) versus general anesthesia (GA) in elderly patients undergoing lower lumbar spine fusion surgeries.

SUMMARY OF BACKGROUND DATA

Lumbar spine surgery can be performed under GA or regional anesthesia. GA is more commonly used in lumbar spine surgery, which renders the patient motionless throughout the procedure and provides a secure airway. Although EA is associated with superior hemodynamic status, reduced duration of operation, less health care cost, and lower rate of surgical complications when compared with GA. Controversy still exists with regard to the optimum choice of anesthesia for major lumbar spine surgery, especially in elderly patients.

MATERIALS AND METHODS

From September 2016 to August 2017, consecutive patients aged 70 years or older who underwent lower lumbar fusion surgery with EA or GA were enrolled in the study. Recorded data for all patients included: age, sex, medical conditions; surgical time, operation procedure, blood loss; intraoperative hypertension and tachycardia; occurrence of nausea, vomiting, delirium, or cardiopulmonary complications. Postoperative pain and satisfaction were also assessed.

RESULTS

A total of 89 patients were included. Of these, 42 patients underwent GA and 47 patients underwent EA. The number of patients experiencing hypertension and tachycardia during anesthesia was significantly increased in the GA group when compared with EA. Patients with EA had significantly less delirium, nausea, and vomiting. The average Visual Analog Scale scores were significantly higher in the GA group at 0-8 hours after surgery. Patients underwent EA were more satisfied than patients with GA.

CONCLUSIONS

There was an association between those who received EA and superior perioperative outcomes. However, some concerns including airway security, operation duration, and obesity, must be carefully evaluated. In addition, it should be noted that this study was retrospective and selection bias may probably exist which may interfere with the results.

A randomized trial of phenylephrine infusion versus bolus dosing for nausea and vomiting during Cesarean delivery in obese women

PURPOSE

Hypotension is common after spinal anesthesia for Cesarean delivery. It is associated with nausea, vomiting, and fetal acidosis. Previous research on phenylephrine excluded obese subjects. We compared the incidence of intraoperative nausea and vomiting (IONV) in obese patients who received a prophylactic phenylephrine infusion vs those who received bolus dosing for the treatment of spinal-induced hypotension.

METHODS

In this multicentre, double-blinded randomized controlled trial, 160 obese women undergoing elective Cesarean delivery under spinal anesthesia were randomized to receive a prophylactic phenylephrine infusion initiated at 50 μg·min^-1 (and titrated according to a predefined algorithm) or 100 μg phenylephrine boluses to treat hypotension. Maternal systolic blood pressure was maintained within 20% of baseline. The primary study outcome was the incidence of IONV.

RESULTS

Intraoperative nausea and vomiting were significantly reduced in the infusion group compared to the bolus group (46% vs 75%, respectively; relative risk [RR], 0.61; 95% confidence interval [CI], 0.47 to 0.80; P < 0.001). This was associated with significantly reduced need for intraoperative rescue antiemetics (26% vs 42%, respectively; RR, 0.62; 95% CI, 0.40 to 0.97; P = 0.04), but no difference in the incidence of vomiting. Postoperative vomiting at two hours was reduced in the infusion group (11% vs 25%; RR, 0.44; 95% CI, 0.21 to 0.90; P = 0.02);however, there were no differences in the incidence or severity of postoperative nausea, need for rescue antiemetics at two hours and 24 hr, or the incidence of postoperative vomiting at 24 hr.

CONCLUSION

In obese women undergoing Cesarean delivery with spinal anesthesia, prophylactic phenylephrine infusion was associated with less intraoperative nausea, less need for rescue antiemetics, and reduced early postoperative vomiting.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT01481740). Registered 22 July 2011.