Difficult epidural placement in obese and non-obese pregnant women: a systematic review and meta-analysis

A prospective randomized double-blind study comparing the dose-response curves of epidural ropivacaine for labor analgesia initiation between parturients with and without obesity

Background: Previous studies have explored the median effective concentration (EC50) of ropivacaine for labor epidural analgesia in parturients with obesity. However, the clinical relevance of the 90% effective concentration (EC90) remains unclear. This study aimed to determine and compare the dose-response curve of epidural ropivacaine for labor analgesia between parturients with and without obesity. Methods: Parturients were divided into two groups based on body mass index (BMI): group N, consisting of parturients with BMI <30 kg/m2, and group O, consisting of parturients with BMI >30 kg/m2. Within each group, the patients were randomized to receive one of five concentrations (0.0375%, 0.075%, 0.1125%, 0.15%, or 0.1875%) of epidural ropivacaine for labor analgesia. Analgesia was induced with a loading dose of 15 mL of the assigned concentration. Visual analogue scale (VAS) scores were recorded at baseline and 30 min post-dose to calculate the response (%) using the formula [(baseline VAS pain score-VAS pain score at 30 min)/baseline VAS pain score] ×100%. The EC50 and EC90 values were determined via nonlinear regression analysis. Results: The EC50 and EC90 values of ropivacaine were 0.061% (95% confidence interval [CI], 0.056%-0.066%) and 0.177% (95% CI, 0.152%-0.206%) in group N and 0.056% (95% CI, 0.051%-0.061%) and 0.161% (95% CI, 0.138%-0.187%) in group O, respectively. No significant differences were observed in the EC50 and EC90 values between the two groups (p-values = 0.121 and 0.351, respectively. Conclusion: In conclusion, within the parameters of this study, our findings suggest that obesity, characterized by a mean BMI value of 30.9, does not significantly influence the EC50 and EC90 values of epidural ropivacaine for labor analgesia. Further investigations are warranted to elucidate the dose-response relationship between ropivacaine and obesity with higher BMI values. Clinical trial registration: https://www.chictr.org.cn/showproj.html?proj=190747, Identifier ChiCTR2300073273.

Anesthetic challenges of pregnant obesity women

Obesity causes significant morbidity and increases the mortality risk for both mother and fetus. With an increasing projected prevalence, it is vital that the obstetric anesthetist is equipped with the knowledge and tools to manage these women. A multi-disciplinary team approach and early planning is required. Neuraxial analgesia for labor helps to negate the need for general anesthesia, which is associated with increased risk in this subset of women. Catheter techniques for neuraxial anesthesia allow for titration, manipulation, and prolongation of the anesthetic block to reduce the risk of conversion to general anesthesia.

Ultrasound-assisted bony landmark palpation in untrained palpators

CONTEXT

Medical students with no previous experience may find it difficult to identify and palpate bony landmarks while learning physical examination skills. In a study of 168 medical schools, 72.6 % have indicated that they are utilizing ultrasound in their curriculum. Although the integration of ultrasound curriculum has become more widespread, the depth of instruction is inconsistent. Ultrasound is not commonly taught in conjunction with palpation of bony landmarks in osteopathic structural examination.

OBJECTIVES

The objective of this analysis was to identify whether utilizing ultrasound assistance in teaching palpation of specific thoracic vertebral bony landmarks would improve palpation accuracy in first-year medical students with no previous palpatory experience.

METHODS

First-year medical students were given video instructions to palpate and identify a thoracic vertebral transverse process and to mark it with invisible ink. The participants were then taught and instructed to utilize ultrasound to identify the same landmark and mark it with a different color. The accuracy of palpation was measured with digital calipers.

RESULTS

A test of the overall hypothesis that participants will show improved accuracy utilizing ultrasound compared with hand palpation was not significant (F=0.76, p>0.05). When separating students into groups according to patient body mass index (BMI), however, there was a trend toward significance (F=2.90, p=0.071) for an interaction effect between patient BMI and the repeated measures variable of palpation/ultrasound. When looking specifically at only those participants working with a normal BMI patient, there was a significant improvement in their accuracy with the use of ultrasound (F=7.92, p=0.017).

CONCLUSIONS

The analysis found increased accuracy in bony landmark identification in untrained palpators utilizing ultrasound vs. palpation alone in a normal BMI model, but not in obese or overweight BMI models. This study shows promise to the value that ultrasound may have in medical education, especially with respect to early palpation training and landmark identification.

Comparison of Performance Characteristics and Efficacy of Bilateral Thoracic Paravertebral Blocks in Obese and Non-Obese Patients Undergoing Reduction Mammaplasty Surgery: A Historical Cohort Study

BACKGROUND

Although ultrasound (US)-guided regional anesthesia techniques are advantageous in the management of obese patients; the procedures can still be associated with technical difficulties and greater failure rates. The aim of this study is to compare the performance properties and analgesic efficacy of US-guided bilateral thoracic paravertebral blocks (TPVBs) in obese and non-obese patients.

METHODS

Data of 82 patients, who underwent bilateral reduction mammaplasty under general anesthesia with adjunctive TPVB analgesia between December 2016 and February 2020, were reviewed. Patients were allocated into two groups with respect to their BMI scores (Group NO: BMI < 30 and Group O: BMI ≥ 30). Demographics, ideal US visualization time, total bilateral TPVB procedure time, needle tip visualization and performance difficulties, number of needle maneuvers, surgical, anesthetic and analgesic follow-up parameters, incidence of postoperative nausea and vomiting (PONV), sleep duration, length of postanesthesia care unit (PACU) and hospital stay, and patient/surgeon satisfaction scores were investigated.

RESULTS

Seventy-nine patients' data were complete. Ideal US visualization and total TPVB performance times were shorter, number of needle maneuvers were fewer and length of PACU stay was shorter in Group NO (p < 0.05). Postoperative pain scores were generally similar within first 24 h (p > 0.05). Time to postoperative pain, total analgesic requirements, incidence of PONV, sleep duration, length of hospital stay were comparable (p > 0.05). Satisfaction was slightly higher in Group NO (p < 0.05).

CONCLUSIONS

US-guided TPVB performances in obese patients might be more challenging and take longer time. However, it is still successful providing good acute pain control in patients undergoing reduction mammaplasty surgeries.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

TRIAL REGISTRATION

NCT04596787.

Obesity in Pregnancy: A Comprehensive Review of Influential Guidelines

Importance

Obesity is one of the most common clinical entities complicating pregnancies and is associated with short- and long-term consequences for both the mother and the offspring.

Objective

The aim of this study were to review and compare the most recently published influential guidelines on the management of maternal obesity in the preconceptional, antenatal, intrapartum, and postpartum period.

Evidence Acquisition

A descriptive review of guidelines from the American College of Obstetricians and Gynecologists, the International Federation of Gynecology and Obstetrics, the Society of Obstetricians and Gynecologists of Canada, the Royal College of Obstetricians and Gynecologists, and the Royal Australian and New Zealand College of Obstetricians and Gynecologists on obesity in pregnancy was carried out.

Results

There is an overall agreement among the reviewed guidelines regarding the importance of prepregnancy weight loss with behavioral modification, optimization of gestational weight gain, and screening for comorbidities in improving pregnancy outcomes of obese women. Women with previous bariatric surgery should be screened for nutritional deficiencies and have a closer antenatal surveillance, according to all guidelines. In addition, folic acid supplementation is recommended for 1 to 3 months before conception and during the first trimester, but several discrepancies were identified with regard to other vitamins, iodine, calcium, and iron supplementation. All medical societies recommend early screening for gestational diabetes mellitus and early anesthetic assessment in obese women and suggest the use of aspirin for the prevention of preeclampsia when additional risk factors are present, although the optimal dosage is controversial. The International Federation of Gynecology and Obstetrics, Society of Obstetricians and Gynecologists of Canada, Royal College of Obstetricians and Gynecologists, and Royal Australian and New Zealand College of Obstetricians and Gynecologists point out that specific equipment and adequate resources must be readily available in all health care facilities managing obese pregnant women. Moreover, thromboprophylaxis and prophylactic antibiotics are indicated in case of cesarean delivery, and intrapartum fetal monitoring is justified during active labor in obese patients. However, there are no consistent protocols regarding the fetal surveillance, the monitoring of multiple gestations, the timing and mode of delivery, and the postpartum follow-up, although weight loss and breastfeeding are unanimously supported.

Conclusions

Obesity in pregnancy is a significant contributor to maternal and perinatal morbidity with a constantly rising global prevalence among reproductive-aged women. Thus, the development of uniform international protocols for the effective management of obese women is of paramount importance to safely guide clinical practice and subsequently improve pregnancy outcomes.

Regional anaesthesia: what surgical procedures, what blocks and availability of a “block room”?

PURPOSE OF REVIEW

With an expected rise in day care procedures with enhanced recovery programs, the use of specific regional anaesthesia can be useful. In this review, we will provide insight in the used regional block and medication so far known and its applicability in a day care setting.

RECENT FINDINGS

Regional anaesthesia has been improved with the aid of ultrasound-guided placement. However, it is not commonly used in the outpatient setting. Old, short acting local anaesthetics have found a second life and may be especially beneficial in the ambulatory setting replacing more long-acting local anaesthetics such as bupivacaine.To improve efficiency, a dedicated block room may facilitate the performance of regional anaesthesia. However, cost-efficacy for improved operating time, patient care and hospital efficiency has to be established.

SUMMARY

Regional anaesthesia has proven to be beneficial in ambulatory setting. Several short acting local anaesthetics are favourable over bupivacaine in the day care surgery. And if available, there are reports of the benefit of an additional block room used in a parallel (monitored) care of patients.

Real-time ultrasound-guided versus anatomic landmark-based thoracic epidural placement: a prospective, randomized, superiority trial

Background

Thoracic epidural placement (TEP) using the conventional anatomic landmark-based technique is technically challenging, may require multiple attempts, and is associated with a high failure rate (12–40%). We hypothesized that real-time ultrasound guidance would be superior in the “first-pass” success rate of TEP, when compared with the conventional technique.

Methods

This prospective, randomized, superiority trial was conducted in a University hospital, and recruited 96 patients undergoing elective major abdominal or thoracic surgery and scheduled to receive a TEP for postoperative analgesia. Patients were randomly allocated to receive TEP using either the conventional technique (Gp-Conv, n = 48) or real-time ultrasound guidance (Gp-Usg, n = 48). The success of TEP was defined as eliciting loss of resistance technique and being able to insert the epidural catheter. The primary outcome variable was the “first-pass success rate” meaning the successful TEP at the first needle insertion without redirection or readvancement of the Tuohy needle. The secondary outcomes included the number of skin punctures, number of attempts, the overall success rate, TEP time, and total procedure time.

Results

The first-pass success rate of TEP was significantly higher (p = 0.002) in Gp-Usg (33/48 (68.8%); 95%CI 55.6 to 81.9) than in Gp-Conv (17/48 (35.4%); 95%CI 21.9 to 49.0). There was no statistically significant difference (p = 0.12) in the overall success rate of TEP between the 2 study groups (Gp-Usg; 48/48 (100%) vs. Gp-Conv; 44/48 (91.7%); 95%CI 83.9 to 99.5). Ultrasound guidance reduced the median number of skin punctures (Gp-Usg; 1 [1, 1] vs Gp-Conv; 2 [1, 2.2], p < 0.001) and attempts at TEP (Gp-Usg; 1 [1, 2] vs Gp-Conv; 3 [1, 7.2], p < 0.001) but the procedure took longer to perform (Gp-Usg; 15.5 [14, 20] min vs Gp-Conv; 10 [7, 14] min, p < 0.001).

Conclusions

This study indicates that real-time ultrasound guidance is superior to a conventional anatomic landmark-based technique for first-pass success during TEP although it is achieved at the expense of a marginally longer total procedure time. Future research is warranted to evaluate the role of real-time ultrasound guidance for TEP in other groups of patients.

Trial registration

Thai Clinical Trials Registry; http://www.thaiclinicaltrials.org/; Trial ID: TCTR20200522002, Registration date: 22/05/2020.

Anesthetic experience does not reduce accidental dural puncture in surgical patients: a retrospective case-controlled study

Background

Accidental dural puncture (ADP), which is a complication of epidural anesthesia, still exists and leads to worse outcomes in surgical patients. While residency training is important for epidural competency, it remains unknown whether anesthetic experience reduces ADP in surgical patients. Using an incident reporting system along with anesthetic records, this case-controlled study retrospectively investigated risk factors associated with ADP in surgical patients.

Methods

Patients who experienced ADP during epidural anesthesia who were registered in the incident reporting system of our institution between April 2012 and March 2019 were enrolled. Patients with ADP were control-matched with those who without ADP in a 1:3 ratio, to compare the potential risk factors and calculated odds ratios (ORs) for ADP. The primary hypothesis was that anesthesiologists’ experience reduces the incidence of ADP. The secondary hypothesis was that there are risk factors for ADP. Between-group differences in anesthesiologists’ experience were compared using the Mann–Whitney U test. Significance was set at P < 0.05.

Results

Thirty-five patients who experienced ADP were identified from the incident reporting system. These were matched with 69 patients who did not experience ADP. There was no difference in the years of experience of anesthesiologists between the groups that did and did not experience ADP (8 [3–20] vs. 9 [3–18] years, respectively; P = 0.65).

Conclusions

Having an experienced anesthesiologist did not guarantee the prevention of ADP. Daily individual training and briefings would be needed to reduce the incidence of ADP.

The association between labour epidural case volume and the rate of accidental dural puncture

Accidental dural puncture is a recognised complication of labour epidural placement and can cause a debilitating headache. We examined the association between labour epidural case volume and accidental dural puncture rate in specialist anaesthetists and anaesthesia trainees. We performed a retrospective cohort study of labour epidural and combined spinal-epidural nerve blocks performed between 1 July 2013 and 31 December 2017 at Waitemata District Health Board, Auckland, New Zealand. The mean (SD) annual number of obstetric epidural and combined spinal-epidural procedures for high-case volume specialists was 44.2 (15.0), and for low-case volume specialists was 10.0 (6.8), after accounting for caesarean section combined spinal-epidural procedures. Analysis of 7976 labour epidural and combined spinal-epidural procedure records revealed a total of 92 accidental dural punctures (1.2%). The accidental dural puncture rate (95%CI) in high-case volume specialists was 0.6% (0.4-0.9%) and in low-case volume specialists 2.4% (1.4-3.9%), indicating probable skill decay. The odds of accidental dural puncture were 3.77 times higher for low- compared with high-case volume specialists (95%CI 1.72-8.28, p = 0.001). Amongst trainees, novices had a significantly higher accidental dural puncture complication rate (3.1%) compared with registrars (1.2%), OR (95%CI) 0.39 (0.18-0.84), p = 0.016, or fellows (1.1%), 0.35 (0.16-0.76), p = 0.008. Accidental dural puncture complication rates decreased once trainees progressed past the 'novice' training stage.

Increased maternal body mass index is associated with prolonged anaesthetic and surgical times for caesarean delivery but is partially offset by clinician seniority and established epidural analgesia

BACKGROUND

Obesity is associated with higher surgical and anaesthetic morbidity and difficulties.

AIMS

We aimed to investigate associations between maternal body mass index (BMI) and the in-theatre time taken to produce an anaesthetised state or to perform surgery for caesarean delivery.

MATERIALS AND METHODS

Using the Strengthening the Reporting of Observational Studies in Epidemiology guidelines, we identified all women who underwent caesarean section at a single institution (2009-2015). The prospectively collected data arising from antenatal and peripartum care were analysed. Generalised linear regression was used to examine associations between maternal BMI and the time taken to anaesthetise the mother and the duration of surgery.

RESULTS

Of a total of 24 761 caesarean deliveries, 5607 (22.7%) women were obese at antenatal registration. In-theatre anaesthetic preparation (18 vs 32 min, P < 0.001) and surgical duration (38 vs 52 min, P < 0.001) were longer in women with BMI ≥50 kg/m² (BMI-50) than those with normal BMI (BMI-N). This difference remained significant after controlling for antenatal, intra-operative and immediate postoperative variables. Modifiable variables were identified that may mitigate the effects of severe obesity. Senior obstetric and anaesthetic care were both independently associated with a significant reduction in mean in-theatre anaesthetic preparation time and surgical duration, by 11 and three minutes respectively (P < 0.001), while epidural top-up significantly lessened mean anaesthetic in-theatre preparation duration by seven minutes (P < 0.001).

CONCLUSIONS

Obese women had greater anaesthesia and surgery time, but the effect may potentially be mitigated by provision of care by experienced staff and prior establishment of epidural analgesia.