Does preprocedural ultrasound prior to lumbar neuraxial anesthesia or analgesia increase first-pass success in adults with obesity? A systematic review

Background and Aims

Preprocedural ultrasound (PPU) reduces the risk of technical failure in non-obese patients and when technical difficulty is predicted. We conducted this review to determine if PPU improves first-pass needle insertion success for neuraxial anesthesia in patients with obesity.

Methods

We conducted a systematic review without meta-analysis, due to the small number of included studies. The study protocol was registered (PROSPERO: CRD42022368271). We conducted searches in MEDLINE, Embase, PubMed, and Cochrane Library from January 1, 1980 to October 1, 2022 for peer-reviewed randomized controlled or observational studies comparing PPU versus landmark techniques in patients with body mass index >30 kg/m2. The quality of evidence was assessed using the revised Cochrane risk-of-bias tool for randomized trials and Grading of Recommendations Assessment, Development, and Evaluation approach.

Results

There were nine randomized controlled studies, comprising 866 patients having lumbo-sacral neuraxial techniques. Three studies utilized a small handheld ultrasound device called Accuro™ and six utilized non-handheld ultrasound devices. Certainty of evidence was low for improving the first-pass success rate. There was evidence (moderate certainty) that PPU decreased number of passes, increased first insertion attempt success, and reduced number of insertion attempts. There was no evidence that PPU affected identifying time, needling time, or overall procedural time. There was no evidence that PPU influenced procedural failure rate (very low certainty evidence) and insufficient evidence to suggest that artificial intelligence-supported handheld devices were superior to conventional ultrasound devices.

Conclusions

In patients with obesity, there is evidence of very-low to moderate certainty that PPU improves markers of insertion success, with no indication of increased adverse effects. PPU should be used to reduce attempts. Further studies adhering to standardized outcome definitions are required for definitive recommendations.

Registration

The study protocol was registered on the International Prospective Register of Systematic Reviews (PROSPERO: CRD42022368271).

Efficacy and safety of ultrasound-guided versus landmark-guided neuraxial puncture: a systematic review, network meta-analysis and trial sequential analysis of randomized clinical trials

BACKGROUND

Data suggest that preprocedural ultrasound may improve the efficacy of central neuraxial puncture. However, it remains uncertain whether these findings can be extended to various clinical scenarios, including diverse patient populations and the application of real-time ultrasound guidance. Additionally, it is unclear whether ultrasound-guided techniques improve safety and patient-centered outcomes.

METHODS

We searched six databases for randomized trials of adult patients undergoing neuraxial puncture, comparing real-time ultrasound, preprocedural ultrasound, and landmark palpation for efficacy, safety and patient-centered outcomes. Our primary outcome was a failed first-attempt neuraxial puncture. After two-person screening and data extraction, meta-analyses were conducted and the Grading of Recommendations Assessment, Development and Evaluation approach was applied to assess the certainty of evidence.

RESULTS

Analysis of 71 studies involving 7153 patients, both real-time ultrasound (OR 0.30; 95% credible interval (CrI) 0.15 to 0.58; low certainty) and preprocedural ultrasound (OR 0.33; 95% CrI 0.24 to 0.44; moderate certainty) showed a significant reduction in the risk of a failed first neuraxial puncture. Real-time ultrasound had the best performance for preventing first-attempt failures (low certainty evidence). Although real-time ultrasound was also the leading method for reducing the risk of complete neuraxial puncture failure, the results did not show a statistically significant difference when compared with landmark palpation. Preprocedural ultrasound, however, significantly reduced the odds of complete puncture failure (OR 0.29; 95% CrI 0.11 to 0.61). These ultrasound-guided approaches also contributed to a reduction in certain complications and increased patient satisfaction without any other significant differences in additional outcomes. Trial sequential analysis confirmed that sufficient information was achieved for our primary outcome.

CONCLUSIONS

Ultrasound-guided neuraxial puncture improves efficacy, reduces puncture attempts and needle redirections, reduces complication risks, and increases patient satisfaction, with low to moderate certainty of evidence. Despite real-time ultrasound's high ranking, a clear superiority over preprocedural ultrasound is not established. These results could prompt anesthesiologists and other clinicians to reassess their neuraxial puncture techniques.

Comparative efficacy of ultrasound guidance or conventional anatomical landmarks for neuraxial puncture in adult patients: a systematic review and network meta-analysis

BACKGROUND

Preprocedural, real-time, and computer-aided three-dimensional ultrasound has been widely used for neuraxial puncture; however, the optimal guidance is unclear. We examined the comparative efficacy of three ultrasound guidance and anatomical landmarks for neuraxial puncture in adults.

METHODS

We searched for randomised controlled studies comparing the efficacy of ultrasound guidance and anatomical landmarks for neuraxial puncture in adults using electronic databases and unpublished studies. The primary outcomes were first-pass success and patient satisfaction. A random-effects network meta-analysis (NMA) was used.

RESULTS

We identified 74 eligible studies (7090 patients). Preprocedural ultrasound and real-time ultrasound-guided neuraxial puncture improved first-pass success compared with anatomical landmarks (risk ratio [RR] 1.6; 95% credible interval [CrI] 1.3-1.9; RR 1.9; 95% CrI 1.3-2.9, respectively, moderate confidence). Computer-aided ultrasound-guided neuraxial puncture also increased first-pass success (RR 1.8; 95% CrI 0.97-3.3, low confidence), although estimates were imprecise. However, real-time ultrasound-guided neuraxial puncture resulted in minimal difference in first-pass success compared with preprocedural ultrasound (RR 1.2; 95% CrI 0.8-1.8, moderate confidence). Preprocedural ultrasound improved patient satisfaction slightly compared with anatomical landmark use (standardised mean differences 0.28; 95% CrI 0.092-0.47, low confidence).

CONCLUSIONS

This NMA provides evidence supporting ultrasound-guided neuraxial puncture compared with use of anatomical landmarks, including indirect comparisons. Among the three ultrasound guidance methods, preprocedural ultrasound appears to be a better adjunctive option.

Ultrasonography versus palpation for spinal anesthesia in obese parturients undergoing cesarean delivery: a randomized controlled trial

INTRODUCTION

Ultrasonography may facilitate neuraxial blocks in obstetrics. This randomized controlled trial aimed to compare preprocedural ultrasonography with landmark palpation for spinal anesthesia in obese parturients undergoing cesarean delivery.

METHODS

280 American Society of Anesthesiologists (ASA) physical status II-III parturients with body mass index ≥35 kg/m2, full-term singleton pregnancy, undergoing elective cesarean delivery under spinal anesthesia, were randomly assigned to two equal groups (ultrasonography and palpation); preprocedural systematic ultrasound approach and conventional landmark palpation were performed, respectively. Patients and outcome assessors were blinded to the study group. All ultrasound and spinal anesthetic procedures were performed by a single experienced anesthesiologist. The primary outcome was the number of needle passes required to obtain free cerebrospinal fluid (CSF) flow. Secondary outcomes were the number of skin punctures required to obtain free CSF flow, success rate at the first needle pass, success rate at the first skin puncture, duration of the spinal procedure, patient satisfaction and incidence of vascular puncture, paresthesia, failure to obtain CSF flow and failed spinal block.

RESULTS

There were no significant differences in primary or secondary outcomes between the two groups. The median (IQR) of the number of needle passes required to obtain free CSF flow was 3 (1-7) in ultrasonography group and 3 (1-7) in palpation group; p=0.62.

CONCLUSIONS

Preprocedural ultrasonography did not decrease the number of needle passes required to obtain free CSF flow or improve other outcomes compared with landmark palpation during spinal anesthesia performed by a single experienced anesthesiologist in obese parturients undergoing cesarean delivery.

TRIAL REGISTRATION NUMBER

NCT03792191; : https://clinicaltrials.gov/ct2/show/NCT03792191.

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.

Accuro ultrasound-based system with computer-aided image interpretation compared to traditional palpation technique for neuraxial anesthesia placement in obese parturients undergoing cesarean delivery: a randomized controlled trial

PURPOSE

Recently, a new handheld ultrasound-based device, called Accuro, has been commercialized with a real-time automated interpretation of lumbar ultrasound images. We hypothesized that the handheld ultrasound device would improve the efficacy and safety of combined spinal-epidural anesthesia (CSEA) for cesarean delivery in obese parturients.

METHODS

Eighty parturients with a body mass index > 30 kg∙m^-2 scheduled for elective cesarean delivery were randomly allocated equally (palpation group and ultrasound group). The primary outcome was the first insertion success rate. Secondary outcomes were the time taken to identify the needle puncture site, duration of CSEA procedure, the total time, the rate of parturients who require needle redirections, the number of skin punctures, changes in the intended interspace, and the incidence of complications.

RESULTS

Compared to the palpation group, the first insertion success rate was significantly higher (72.5% vs. 40.0%; P = 0.003), and time taken to identify the needle puncture site was less (30 [26-36] vs. 39 [32-49] seconds; P = 0.001) in the ultrasound group. The rate of parturients who required needle redirections (40.0% vs. 72.5%; P = 0.003) and the incidence of paresthesia were both lower (7.5% vs. 45.0%; P < 0.001). The other outcomes had no significant difference between groups. The mean difference between the epidural depth measured by the handheld ultrasound and needle depth was - 0.29 cm [95% limit of agreement, - 0.52 to - 0.05].

CONCLUSIONS

Our study suggests using the Accuro ultrasound device can enhance the efficacy and safety of CSEA in obese parturients when executed by experienced anesthesiologists, and its automated estimation of epidural depth is accurate.

Conventional landmark palpation vs. preprocedural ultrasound for neuraxial analgesia and anaesthesia in obstetrics - a systematic review and meta-analysis with trial sequential analyses

The aim of this systematic review and meta-analysis was to examine the efficacy, time taken and the safety of neuraxial blockade performed for obstetric patients with the assistance of preprocedural ultrasound, in comparison with the landmark palpation method. The bibliographic databases Central, CINAHL, EMBASE, Global Health, MEDLINE, Scopus and Web of Science were searched from inception to 13 February 2020 for randomised controlled trials that included pregnant women having neuraxial procedures with preprocedural ultrasound as the intervention and conventional landmark palpation as the comparator. For continuous and dichotomous outcomes, respectively, we calculated the mean difference using the inverse-variance method and the risk ratio with the Mantel-Haenszel method. In all, 22 trials with 2462 patients were included. Confirmed by trial sequential analysis, preprocedural ultrasound increased the first-pass success rate by a risk ratio (95%CI) of 1.46 (1.16-1.82), p = 0.001 in 13 trials with 1253 patients. No evidence of a difference was found in the total time taken between preprocedural ultrasound and landmark palpation, with a mean difference (95%CI) of 50.1 (-13.7 to 113.94) s, p = 0.12 in eight trials with 709 patients. The quality of evidence was graded as low and very low, respectively, for these co-primary outcomes. Sub-group analysis underlined the increased benefit of preprocedural ultrasound for those in whom the neuraxial procedure was predicted to be difficult. Complications, including postpartum back pain and headache, were decreased with preprocedural ultrasound. The adoption of preprocedural ultrasound for neuraxial procedures in obstetrics is recommended and, in the opinion of the authors, should be considered as a standard of care, in view of its potential to increase efficacy and reduce complications without significant prolongation of the total time required.