Increasing body mass index and abdominal subcutaneous fat thickness are associated with increased skin-to-epidural space distance in pregnant women

Impact of anesthesiologist experience on neuraxial anesthesia outcomes in cesarean sections

BACKGROUND

Despite the requirement for meticulous management of cesarean anesthesia, no study has explored the impact of novice trainee anesthesiologists in this field. This study assessed challenges in neuraxial anesthesia for cesarean sections and compared outcomes between novice and senior anesthesiologists.

METHODS

We retrospectively analyzed 446 cesarean sections with neuraxial anesthesia. The primary objective was to evaluate the impact of anesthesiologists' experience on the time required to administer neuraxial anesthesia and whether maternal body mass index (BMI) influenced this relationship. Secondary objectives included examining maternal hemodynamic variability, operative details, and newborn outcomes relative to the anesthesiologist's experience.

RESULTS

Novice anesthesiologists required a significantly longer time to perform neuraxial anesthesia (24.9 [7.1] min vs. 18.2 [7.0] min, P<0.001) than their senior counterparts. A significant interaction was observed between anesthesiologist experience and maternal BMI on the time to administer neuraxial anesthesia (P=0.017), with a moderate correlation between BMI and administration time for novices (r=0.50, P<0.001) and only a slight correlation for seniors (r=0.17, P=0.001). Experience level did not significantly affect intraoperative hemodynamics, Apgar scores, or umbilical cord blood gas analyses.

CONCLUSIONS

The effect of maternal BMI on the difficulty of performing neuraxial anesthesia in parturients can be more pronounced for novice anesthesiologists than for experienced ones. Despite requiring more time to perform neuraxial anesthesia, novice anesthesiologists do not significantly affect maternal hemodynamics or newborn distress during obstetric anesthesia, provided that they are under the supervision of experienced anesthesiologists.

Quantitative Evaluation of the Lumbar Multifidus Muscle by Shear Wave Dispersion in Healthy Adults: A Preliminary Study

OBJECTIVES

To investigate the application value of shear wave dispersion (SWD) in healthy adults with the lumbar multifidus muscle (LMM), to determine the range of normal reference values, and to analyze the influences of factors on the parameter.

METHODS

Ninety-five healthy volunteers participated in the study, from whom 2-dimensional, shear wave elastography (SWE), and SWD images of the bilateral LMM were acquired in three positions (prone, standing, and anterior flexion). Subcutaneous fat thickness (SFH), SWE velocity, and SWD slope were measured accordingly for analyses.

RESULTS

The mean SWD slope of the bilateral LMM in the prone position was as follows: left: 14.8 ± 3.1 (m/second)/kHz (female) and 13.0 ± 2.5 (m/second)/kHz (male); right: 14.8 ± 3.7 (m/second)/kHz (female) and 14.2 ± 3.4 (m/second)/kHz (male). In the prone position, there was a weak negative correlation between the bilateral LMM SWD slope of activity level 2 and level 1 (β = -1.5 (2 versus 1, left), -1.9 (2 versus 1, right), all P < .05), and between the left SWD slope of activity level 3 and level 1 (β = -2.3 [3 versus 1, left], P < .05). The correlation between SWE velocity and SWD slope value changed with the position: there was a weak positive correlation in the prone position (r = 0.3 [left], 0.37 [right], both P < .05), and a moderate positive correlation in the standing and anterior flexed positions (r = 0.49-0.74, both P < .001). SFH was moderately negatively correlated with bilateral SWD slope values in the anterior flexion (left: r = -0.4, P = .01; right: r = -0.7, P < .01).

CONCLUSIONS

SWD imaging can be used as an adjunct tool to aid in the assessment of viscosity in LMM. Further, activity level, and position are influencing factors that should be considered in clinical practice.

Mathematical Models for the Skin to Lumbosacral Epidural Distance in Dogs: A Cadaveric Computed-Tomography Study

This study aimed to validate previously published computed tomography (CT) derived mathematical equations with the true skin to lumbosacral epidural distance (SLED) in dog cadavers. Phase 1: The lumbar region of 11 dog cadavers were scanned in sternal recumbency to determine the effect of cranial, neutral, and caudal pelvic limb positioning on the CT derived lumbosacral epidural distance (CLED). Phase 2: The epidural space was determined using contrast epidurography, and the SLED was analysed against the mathematical equations using a body condition score (BCS) and either the cadaveric occipital-coccygeal length (OCL) (Equation (1): = 7.3 + 0.05*OCL + 16.45*BCS) or the ilium wing distance (IWD) (Equation (2): = 3.5 + 0.56*IWD + 16.6*BCS). There were no differences detected between the pelvic limb positions and the CLED. Both equations demonstrated strong correlations (Equation (1): r = 0.7196; Equation (2): r = 0.7590) with the SLED. The level of agreement was greater for Equation (1) than with Equation (2) (concordance coefficient 0.6061 and 0.3752, respectively). Equation (1) also demonstrated a closer fit to the concordance line compared with Equation (2) (bias correction factor 0.8422 and 0.4960, respectively). Further studies in live anaesthetised dogs will help to determine the usefulness of the pre-procedural knowledge when performing lumbosacral epidurals.

A randomized trial to investigate needle redirections/re-insertions using a handheld ultrasound device versus traditional palpation for spinal anesthesia in obese women undergoing cesarean delivery

BACKGROUND

Ultrasound may be useful to identify the spinal anesthesia insertion point, particularly when landmarks are not palpable. We tested the hypothesis that the number of needle redirections/re-insertions is lower when using a handheld ultrasound device compared with palpation in obese women undergoing spinal anesthesia for cesarean delivery.

METHODS

Study recruits were obese (body mass index (BMI) >30 kg/m²) women with impalpable bony landmarks who were undergoing spinal anesthesia for elective cesarean delivery. Women were randomized to ultrasound or palpation. The primary study outcome was a composite between-group comparison of total number of needle redirections (any withdrawal and re-advancement of the needle and/or introducer within the intervertebral space) or re-insertions (any new skin puncture in the same or different intervertebral space) per patient. Secondary outcomes included insertion site identification time and patient verbal numerical pain score (0-10) for comfort during surgical skin incision.

RESULTS

Forty women completed the study. The mean BMI (standard deviation) for the ultrasound group was 39.8 (5.5) kg/m² and for the palpation group 37.3 (5.2) kg/m². There was no difference in the composite primary outcome (median (interquartile range) [range]) between the ultrasound group (4 (2-13) [2-22]) and the (6 (4-10) [1-17]) palpation group (P=0.22), with the 95% confidence interval of the difference 2 (-1.7 to 5.7). There were no differences in the secondary outcomes.

CONCLUSIONS

Handheld ultrasound did not demonstrate any advantages over traditional palpation techniques for spinal anesthesia in an obese population undergoing cesarean delivery, although the study was underpowered to show a difference.

Epidural analgesia in the obese obstetric patient: a retrospective and comparative study with non-obese patients at a tertiary hospital

BACKGROUND AND OBJECTIVES

Obesity is becoming a frequent condition among obstetric patients. A high body mass index (BMI) has been closely related to a higher difficulty to perform the neuraxial technique and to the failure of epidural analgesia. Our study is aimed at analyzing obese obstetric patients who received neuraxial analgesia for labor at a tertiary hospital and assessing aspects related to the technique and its success.

METHODS

Retrospective observational descriptive study during one year. Women with a BMI higher than 30 were identified, and variables related to the difficulty and complications of performing the technique, and to analgesia failure rate were assessed.

RESULTS AND CONCLUSIONS

Out of 3653 patients, 27.4% had their BMI ≥ 30 kg.m-². Neuraxial techniques are difficult to be performed in obese obstetric patients, as showed by the number of puncture attempts (≥ 3 in 9.1% obese versus 5.3% in non-obese being p < 0.001), but the incidence of complications, as hematic puncture (6.6%) and accidental dural puncture (0.7%) seems to be similar in both obese and non-obese patients. The incidence of cesarean section in obese patients was 23.4% (p <  0.001). Thus, an early performance of epidural analgesia turns out to be essential to control labor pain and to avoid a general anesthesia in such high-risk patients.

Computed Tomography-Derived Occipital-Coccygeal Length and Ilium Wing Distance Correlates with Skin to Epidural and Intrathecal Depths in Dogs

The current clinical techniques for neuraxial needle placement in dogs are predominantly blind without prior knowledge of the depth required to reach the desired space. This study investigated the correlation and defined the relationship between easily obtainable external landmark variables in the dog; occipital-coccygeal length (OCL) and ilium wings distance (IWD), with the skin to epidural and intrathecal space distances using computed tomography (CT). The CT images of 86 dogs of different breeds were examined in this retrospective observational study. Images of dogs in sternal recumbency were optimized to the sagittal view. The distances between the skin and lumbosacral epidural space (LSE) and skin to sacrococcygeal space (SCE) were measured to the ligamentum flavum surrogate (LFS) line. The distance between the skin and the intrathecal space (ITS) was measured from the skin to the vertebral canal at the interlumbar (L5-L6) space. Measurements of the IWD and OCL were performed on dorsal and scout views, respectively. Linear regression equations and Pearson's correlation coefficients were calculated between variables. Data were reported as mean (standard deviation). Significance was set as alpha < 0.05. After exclusion of four dogs, 82 CT scans were included. The depths were LSE 45 (15) mm, SCE 23 (10) mm, and ITS 50 (15) mm. There was a moderate correlation between OCL with LSE (=14.2 + OCL * 0.05 (r = 0.59, p < 0.0001)), and a strong correlation with ITS (=11.4 + OCL * 0.07 (r = 0.76, p < 0.0001)), while a very weak correlation was found with SCE (=14.0 + OCL * 0.02 (r = 0.27, p < 0.0584)). Similarly, with IWD, there was a moderate correlation with LSE (=10.8 + IWD * 0.56 (r = 0.61, p < 0.0001)), and strong correlation with ITS (=9.2 + IWD * 0.67 (r = 0.75, p < 0.0001)), while a weak correlation was found with SCE (=11.2 + IWD * 0.2 (r = 0.32, p < 0.0033)). Mathematical formulae derived from the multiple regression showed that the body condition score (BCS) improved the relationship between IWD and OCL and the LSE, SCE and ITS, while the addition of body weight was associated with multicollinearity. Further studies are required to determine the accuracy of the algorithms to demonstrate their ability for prediction in a clinical setting.

Prospective observational investigation of body habitus measurements and relationship to epidural depth in term pregnant women

BACKGROUND

High body mass index (BMI) can predict difficult neuraxial block; however, fat distribution may also be important. The primary study aim was to identify body habitus and fat distribution measurements that correlated with ultrasound measured epidural depth. We hypothesized that measurements such as midarm and subscapular fatpad thicknesses and length of cervical spine may correlate better with ultrasound measured epidural depth than a global measure of BMI.

METHODS

Prospective IRB approved study of term pregnant women requiring neuraxial block. We measured height, weight (BMI, kg/m² ), subscapular, midarm fatpad thickness (digital caliper, mm), vertebral column length (C7 to sacral hiatus, cm) and epidural depth (ultrasound, mm). Four experts assessed photographs to assign anticipated difficult neuraxial block in sitting and lateral positions (5-point Likert scale, 1 = very easy, 5 = very difficult).

RESULTS

In all, 131 women completed body habitus measurements. Measured mean (standard deviation) BMI was 30.3 (5.4) kg/m² . Measured BMI, subscapular fatpad and midarm fatpad thickness were significantly correlated with ultrasound depth to epidural space (R² 0.733, 0.626 and 0.633, respectively, P < .0001) but vertebral column length was not. The experts had a high level of agreement (Cronbach's alpha >0.7) for assessment of anticipated difficult block in the sitting and lateral positions; however, anticipated difficult block was not correlated with epidural depth measured by ultrasound for sitting position, R²  = -0.015, P = .87; and lateral position, R²  = -0.087, P = .33.

CONCLUSIONS

Measurements of body habitus and fat distribution were no better than measured BMI to anticipate greater ultrasound measured depth to epidural space. Clinical trial number: Non-interventional observational study, not registered.