Factors predicting difficult spinal block: A single centre study

Performance of the ratio of posterior complex length to depth measured by ultrasound as a predictor of difficult spinal anesthesia for elective cesarean delivery: a prospective cohort study

PURPOSE

Ultrasound view of the interlaminar structure is likely to be associated with difficult spinal anesthesia (DSA), and a poor ultrasound view which cannot show the anterior and posterior complex predicts a difficult spinal technique. As our target site is the posterior complex, this study aimed to assess whether the ratio of posterior complex length to depth measured by ultrasound can predict DSA in cesarean delivery.

METHODS

Four anesthesiologists with 1-2 years of experience located and marked the puncture interspace using a traditional surface landmark. Subsequently, the ultrasound examiner located and measured the marked interspace via an oblique parasagittal ultrasound scan. The anesthesiologists, who were blinded to the ultrasound results, performed spinal anesthesia using a 25-gauge Whitacre spinal needle. The total number of attempts, including skin punctures and needle passes, was recorded and the DSA was defined as 10 unsuccessful attempts. A multivariable logistic regression analysis was used to determine the independent predictors, and receiver operating characteristic curves were constructed to evaluate the performance of the ratio of posterior complex length to depth for predicting DSA.

RESULTS

A total of 397 cesarean delivery parturients with successfully measured posterior complex were included in the analysis. DSA occurred in 64 parturients (16.1%). Reduced length [odds ratio (OR) = 0.010, 95% confidence interval (CI), 0.002-0.062, P < 0.001] and increased depth [OR = 6.127, 95% CI, 2.671-14.056, P < 0.001] of the posterior complex were independently predictive of DSA compared with body mass index, abdominal circumference, and palpable surface landmarks. The ratio of posterior complex length to depth for predicting DSA had an area under the curve of 0.86 (95% CI, 0.82-0.90). The optimal cutoff was 0.23, with a sensitivity of 86% (95% CI, 74-93%) and specificity of 72% (95% CI, 67-77%).

CONCLUSION

The ratio of posterior complex length to depth measured by ultrasound demonstrated a considerable accuracy in predicting DSA for inexperienced anesthesiologists. A higher ratio at ultrasound is an indication to evaluate the optimal puncture body position and interspace in the clinic practice.

CLINICAL TRIAL REGISTRATION

ChiCTR2200065171 https://www.chictr.org.cn/showproj.html?proj=180855.

A Systemic Review of Spinal Needles Broken During Neuraxial Anesthesia

Needle breakage during spinal anesthesia occurs infrequently and represents a serious complication with potentially adverse effects. The objective of this systemic review was to look at the incidence, risk factors, and preventative measures for broken spinal needles. A search of the literature on PubMed, Web of Science, and Embase databases and a manual web search was performed, with no filters and up to April 2023 from inception. Out of the 43 potential studies, 23 were included. The search terms for the full article reading were broken needle, spinal anesthesia, humans, and post-operative, and the exclusion criteria were systematic reviews, conference presentations, and non-full articles. A review of the 23 studies (24 cases) suggests an association between specific risk factors such as obesity and needle size and breaks. Identifying the risks and complications of needle breaks could help physicians modify their practice and inform their patients of any increased risks applicable to them.

Comparison of accuracy between augmented reality/mixed reality techniques and conventional techniques for epidural anesthesia using a practice phantom model kit

BACKGROUND

This study used an epidural anesthesia practice kit (model) to evaluate the accuracy of epidural anesthesia using standard techniques (blind) and augmented/mixed reality technology and whether visualization using augmented/mixed reality technology would facilitate epidural anesthesia.

METHODS

This study was conducted at the Yamagata University Hospital (Yamagata, Japan) between February and June 2022. Thirty medical students with no experience in epidural anesthesia were randomly divided into augmented reality (-), augmented reality (+), and semi-augmented reality groups, with 10 students in each group. Epidural anesthesia was performed using the paramedian approach with an epidural anesthesia practice kit. The augmented reality (-) group performed epidural anesthesia without HoloLens2Ⓡ and the augmented reality (+) group with HoloLens2Ⓡ. The semi-augmented reality group performed epidural anesthesia without HoloLens2Ⓡ after 30 s of image construction of the spine using HoloLens2Ⓡ. The epidural space puncture point distance between the ideal insertion needle and participant's insertion needle was compared.

RESULTS

Four medical students in the augmented reality (-), zero in the augmented reality (+), and one in the semi-augmented reality groups failed to insert the needle into the epidural space. The epidural space puncture point distance for the augmented reality (-), augmented reality (+), and semi-augmented reality groups were 8.7 (5.7-14.3) mm, 3.5 (1.8-8.0) mm (P = 0.017), and 4.9 (3.2-5.9) mm (P = 0.027), respectively; a significant difference was observed between the two groups.

CONCLUSIONS

Augmented/mixed reality technology has the potential to contribute significantly to the improvement of epidural anesthesia techniques.

Predictors of Failed Spinal Arachnoid Puncture Procedures: An Artificial Neural Network Analysis

Background Knowing the predicting factors for difficult neuraxial blocks might help better plan the procedure. This study aimed to determine the predictors of failed spinal arachnoid puncture procedures using artificial neural network (ANN) analysis. Methodology With approvals, prospectively collected data from 300 spinal arachnoid punctures in the operation theater of an academic institute having postgraduate anesthesia training were retrospectively evaluated. Fifteen variables from anthropo-demographic, spinal surface anatomy, procedure, and performers' experiences were fed as input for the ANN. A failed spinal arachnoid puncture procedure was defined as the requirement of more than three punctures, with three punctures but more than six passes, or if the performer handed over the procedure to another, considering it difficult after the second puncture. STATCRAFT v.2 software (Predictive Analytics Solutions Pvt. Ltd., Bengaluru, India) was used for ANN model generation. Considering the overfitting tendency of the ANN, Pr(>|z|) < 0.01 in the ANN was considered significant. The area under the receiver operating characteristic (AuROC) curve of the ANN model and its sensitivity and specificity were also assessed. Significant factors with multiple gradings were also evaluated for their statistical significance across the grades or classes using INSTAT software (Graphpad Prism, La Jolla, CA, USA); a two-tailed P-value of <0.05 was considered significant. Results Interspinous process-based spine grade, performers' experience, and positioning difficulty were significant determinants of failed spinal arachnoid puncture procedures in the ANN model. The ANN model had an AuROC of 0.907, specificity of 0.976, and sensitivity of 0.385. The interclass comparison showed that increasing spinal grades and decreasing experiences were associated with increased pass and puncture. Conclusions The ANN model found the determinants of the failed spinal arachnoid puncture procedure well with good AuROC and specificity but poor sensitivity.