Epidural Depth Research Articles

To evaluate and correlate the effectiveness of epidural depth equation versus pre-procedural US guided epidural block: A randomized controlled trial

To evaluate and correlate the effectiveness of epidural depth equation versus pre-procedural US guided epidural block: A randomized controlled trial

Transverse ultrasound scanning of lumbar-epidural depth and its co-relation with conventional method: A prospective observational study in obese Indian parturients

Pre-procedural ultrasound (US) imaging as a tool of determining the proper insertion site and assessing lumbar-epidural depth in obese Indian parturients. The current study’s goal was to assess the epidural depth space in obese Indian parturients by ultrasound imaging with conventional technique and also to assess whether if it decreases the failure rate and number of attempts. Twenty-five obese parturients with a BMI of more than 30 kg/m who were scheduled for elective lower segment caesarean sections under lumbar epidural anesthesia and were classified as American Society of Anaesthesiology grade I & II were included. Using a curvilinear US probe (frequency 2–5 MHz), ultrasound depth-UD (lumbar epidural) was recorded in the transverse axial plane at the L3–L4 and L4–L5 intervertebral regions. Afterwards, the needle depth (ND) was monitored using a sterile linear scale during the epidural administration process using the traditional loss of resistance (LOR) approach. Any modifications to the intervertebral spacing, needle reorientation, or the quantity of tries were recorded. The results showed that UD and ND were, respectively, 4.6140 ± 0.252 cm (range 4.20–5.30 cm) and 4.720 ± 0.271 cm (range 4.2–5.5 cm). Pearson's correlation coefficient (r) for UD and ND was 0.953 (95% confidence interval: 0.8948–0.9793, r = 0.908, P < 0.001), and the 95% limits of agreement were found to be 0.266 to 0.546 cm using Bland-Altman analysis. Of all the subjects, 92% needed only one try to put the epidural, whereas 8% needed two. The current study demonstrates a significant association of ultrasound (UD) and needle depth (ND) in obese pregnant females (BMI >30 kg/m). For lumbar epidurals, a preprocedural US scan in the transverse-axial plane provides a precise needle entry site with a high success rate.

Factors associated with an inadvertent dural puncture or post-dural puncture headache following labour epidural analgesia: A retrospective cohort study

Inadvertent dural puncture and post-dural puncture headache are complications of labour epidural analgesia and may result in acute and chronic morbidity. Identification of risk factors may enable pre-emptive management and reduce associated morbidity. In this retrospective cohort study, we aimed to identify factors associated with an inadvertent dural puncture or post-dural puncture headache by identifying parturients who received labour epidural analgesia from January 2017 to December 2021. The primary outcome was any witnessed inadvertent dural puncture, inadvertent placement of an intrathecal catheter, clinical diagnosis of post-dural puncture headache, or headache that was assessed to have characteristic post-dural puncture headache features. A wide range of demographic, obstetric, and anaesthetic factors were analysed using univariate and multivariable analyses to identify independent associations with the primary outcome.Data from 26,395 parturients were analysed, of whom 94 (0.36%) had the primary outcome. Within these 94 parturients, 26 (27.7%) had inadvertent dural puncture, 30 (31.9%) had inadvertent intrathecal catheter, and 38 (40.4%) had post-dural puncture headache without documented inadvertent dural puncture or intrathecal catheter insertion. Increased number of procedure attempts (adjusted odds ratio 1.39, 95% confidence interval 1.19 to 1.63), longer procedure duration adjusted odds ratio 1.03, 95% confidence interval 1.01 to 1.05), increased depth of epidural space (adjusted odds ratio 1.10, 95% confidence interval 1.04 to 1.18), greater post-procedure Bromage score (adjusted odds ratio 7.70, 95% confidence interval 4.22 to 14.05), and breakthrough pain (adjusted odds ratio 3.97, 95% confidence interval 2.59 to 6.08) were independently associated with increased odds of the primary outcome, while the use of standard patient-controlled epidural analgesia (PCEA) regimen (adjusted odds ratio 0.50, 95%confidence interval 0.31 to 0.81), increased concentration of ropivacaine (adjusted odds ratio 0.08 per 0.1%, 95% confidence interval 0.02 to 0.46), and greater satisfaction score (adjusted odds ratio 0.96, 95% confidence interval 0.95 to 0.97) were associated with reduced odds. The area under curve of this multivariable model was 0.83.We identified independent association factors suggesting that greater epidural depth and procedure difficulty may increase the odds of inadvertent dural puncture or post-dural puncture headache.

Correlation between epidural space depth measured with ultrasound and MRI compared to clinical loss of resistance when performing lumbar epidural steroid injection

BackgroundThis prospective study assessed the accuracy of MRI and ultrasound (US) measurements as a preprocedural assessment tool for predicting clinical loss of resistance depth (CLORD) during fluoroscopy-guided lumbar epidural steroid...

Ultrasound estimates of the epidural depth in the paramedian sagittal oblique and transverse median planes: the correlation between estimated and actual depth to the epidural space in children with scoliosis

IntroductionThe present study aimed to compare the correlation and agreement of epidural depth estimation using ultrasound in the paramedian sagittal oblique (PSO) versus the transverse median (TM) plane relative to...

Predictors of Epidural Depth and the Role of Technology

Predictors of Epidural Depth and the Role of Technology

Ultrasound: A novel alternative technique for cervical epidural space visualization-A pilot study.

Neuraxial ultrasound (US), a newer modality, can be used for neuraxial imaging, helping in visualizing and aiding in epidural space catheterization. The aim of this study was to evaluate the efficacy of the US for cervical epidural access and to determine the failure rate and complication associated with this technique. A prospective single-arm pilot study was conducted on 21 participants. The neuraxial US image quality assessment by Ultrasound Visibility Score (UVS), epidural space depth measurement by US and by conventional loss of resistance (LOR) technique, and post-procedure epidural catheter confirmation by real-time US were the study parameters. Any procedural complications or failure rate were recorded. The Kolmogorov-Smirnov test, paired-samples t-test, and Chi-square test were used for the statistical comparison. The pre-procedural UVS by the transverse interlaminar view (x/21) was 2.81 ± 1.94 and by the oblique paramedian sagittal view was 16.66 ± 2.39 with UVS being best in the paramedian oblique sagittal view (P- value < 0.05). The comparison of depth of the epidural space identified by USG and that by the LOR technique was statistically insignificant (P = 0.83). The average puncture attempts were 1.1 ± 0.3. Post-procedure US epidural catheter confirmation score (x/3) was 1.44 ± 0.44 with either epidural space expansion or microbubbles seen or both. The pilot study has successfully demonstrated the implication of US for visualizing and aiding in epidural space catheterization. Also, the failure rate and procedural complications were drastically minimized with the help of US as compared to the traditional blind technique.

Prediction of the Cervical Epidural Space Depth from the Skin Using Cervical X-Ray, During Cervical Epidural Block with Paramedian Approach.

The purpose of this study is to compare the actual needle depth measured during cervical epidural block (CEB) with the predicted needle depth measured through a cervical flexion x-ray image at the paramedian approach. The study was conducted based on the medical records of patients who underwent CEB at the pain clinic of Haeundae Paik Hospital. The actual needle distance (AD) was recorded after each successful CEB. The distance from the spinolaminar line to the skin, predicted median depth (PMD), was measured using lateral x-ray images. The medial to lateral distance (MLD), which is the distance from the midline of the spine to the needle insertion point, was measured using anteroposterior (AP) x-rays. The predicted paramedian depth (PPD) was calculated using the Pythagorean formula. The PMD represents the expected depth of the median approach, while the PPD represents the expected depth of the paramedian approach. The PMD, PPD, and AD were compared with each other. Concordance correlation coefficient (CCC) and Bland-Altman analysis were obtained for PMD and PPD. The CCC value of PMD was measured as 0.829, and the CCC value of PPD was measured as 0.830. In the Bland-Altman analysis, PPD was measured at -0.13 ± 8.37 mm, and PMD was measured at 1.29 ± 8.38 mm. When performing CEB through the paramedian approach, the depth can be predicted using a cervical flexion x-ray. At this time, the PMD can also be used to predict the depth during the paramedian approach.

Needle Depth and Angle for Lumbar Interlaminar Epidural Injection Using Magnetic Resonance Imaging and C-Arm Measurements

BACKGROUND: Interlaminar epidural injection (ILEI) is used to relieve low back pain, with or without radiating pain. The distance from the skin to the epidural space determines the needle depth and may be influenced by the patient’s body measurements. OBJECTIVES: The objective of this study was to investigate the correlation between needle depth for ILEI and patients’ body profiles, including weight, height, and body mass index (BMI), using magnetic resonance imaging (MRI) and also to compare the needle depth and angle between MRI and C-arm fluoroscopic images of ILEI. STUDY DESIGN: This was a retrospective study. SETTING: This study was conducted at a single Department of Anesthesiology and Pain Medicine of Konkuk University Medical Center. METHODS: This retrospective study reviewed patients who underwent MRI and ILEI. The needle depth and caudal angle were measured on the sagittal view of MRI and C-arm images for L3–L4, L4–L5, and L5–S1 ILEI. RESULTS: Overall, 386 patients were reviewed. For MRI, the mean value of the needle angle given caudally was 14.70, 12.06, and 11.33 for L3–4, L4–5, and L5–S1 ILEIs, respectively. Mean values of needle depth were 52.17, 52.09, and 47.91 mm for L3-4, L4-5, and L5–S1 ESIs, respectively. Height combined with weight and BMI had a higher correlation with needle depth than weight and height. In the comparison between MRI and fluoroscopy, needle depth at L5–S1 and caudal angle at L3–4 and L4–5 were significantly correlated. LIMITATIONS: This study was a retrospective study conducted at a single center. CONCLUSION: Height combined with weight and BMI can help estimate the optimal needle depth from the skin to the epidural space. Needle depth in L5–S1 and caudal angle in L3–4 and L4–5 of MRI were correlated with those of fluoroscopy of ILEI. KEY WORDS: Body mass index, epidural depth, obesity, morbid, injections, epidural, magnetic resonance imaging, C-arm fluoroscopic images, low back pain, umbosacral pain IRB approval was obtained from the Institutional Review Board of Konkuk University Hospital (IRB file No. 2020-04-011).

Comparison of Magnetic Resonance Imaging and Intraprocedural Cervical Epidural Depth: A Case Series

BACKGROUND: Cervical epidural depth is assessed intraprocedurally using loss-of-resistance technique and fluoroscopy. It would be helpful if this depth could be predicted using magnetic resonance imaging (MRI) images. METHODS: This is a case series of 10 patients undergoing cervical epidural steroid injections (CESIs). The following measurements were made: intraprocedural depth, measured on Tuohy needles intraprocedurally, and MRI depth, measured from the MRI cervical spine. Linear regression models were used to compare the 2 depths. RESULTS: For intraprocedural depth vs sagittal MRI depth, R (Version 4.2.0, R Foundation for Statistical Computing, Vienna, Austria, 2021) was 0.8744, P value &lt; 0.0001. For intraprocedural depth vs axial MRI depth, R was 0.8582, P value &lt; 0.001. CONCLUSIONS: Knowledge of the cervical epidural depth prior to CESIs may improve the safety and efficacy of these procedures. KEY WORDS: Cervical epidural depth, cervical radiculopathy, cervical epidural steroid injections, MRI depth, case series

Measurements of Epidural Space Depth Using Pre-Existing CT-Scan Correlate with Loss of Resistance Depth during Lumber Epidural Catheter Placement

Background: The use of epidural catheters provides the best quality intra- and post-operative pain relief for various major thoraco-abdominal and lower limb surgeries. The process of placing an epidural catheter into the epidural space between the vertebrae can be challenging due to variations in spinal anatomy of different level, narrow intervertebral spaces and can cause catastrophic neurological complications. Though various studies have been shown to overcome the placement of epidural catheter using standard ultrasound method, using the pre-existing computer tomography depth correlate with loss of resistance in placing the epidural catheter would be a well adjunct tool for the procedure. Objectives: To correlate measurements taken from pre-existing computed tomography (CT) imaging to the loss of resistance depth as recorded during epidural placement. Methods: This Single procedural observational study was performed in Combined Military Hospital (CMH), Dhaka from 1st December 2018 to 30th November 2019. Fifty adult patients scheduled for lower abdominal and lower limb surgery under epidural anaesthesia (EA). The patient’s advised/routine abdominal CT film was inspected by a radiologist, who was blinded to the results of the actual needle length, to determine the distance from the skin to the ligamentum flava the corresponding level of L2 to L5 interspinous spaces. The distance on the CT film in the midline was measured using a ruler against the measurement scale, conventionally represented as a 5 cm-10 cm scale with 1-cm divisions. The CT-derived depth was calculated using the principle of Pythagorean triangle trigonometry. Result: In this study, Sixty eight percentages of patients (68%) Epidural- skin distance (ESD) had 4.7-6.8cm. Mean Epidural-skin distance 5.8±1.7cm. On evaluation of Loss of Resistance Depth, 46% of patients had 5.2-7.3cm depth of LOR, followed by 30% patients had 3.0-5.1cm and 12% patients had 7.4-9.5cm. Mean loss of resistance depth was 6.3±1.4 cm. It was evident from this study that positive significant correlation (r=0.941; p=0.001) between the CT-derived distance and Loss of Resistance Depth. Conclusion: It is conclude that using pre-existing CT-scan derived distance is helpful in prediction of the epidural space depth and it is correlates with actual loss of resistance epidural needle insertion depth placing the catheter in lumber region.

Preprocedural ultrasonography as an adjunct to landmark technique for identification of epidural space in parturients for labor analgesia.

Pregnancy-induced softening of tissues and ligaments may increase the false-positive rates when identifying the epidural space in parturients by the landmark technique. To mitigate these problems, Ultrasonography (USG), which has now become the eye of anesthesiologists, can be used as a reliable tool to facilitate more accurate epidural needle placement in parturients. This study was conducted to know the efficacy of USG when compared to the traditional landmark method. After the approval from the institutional ethics committee and CTRI registration, 62 parturients of ASA-2 requesting labor analgesia were randomized into 2 groups of 31 each: Group-L (conventional landmark technique) and Group-U (preprocedural USG done before epidural). In group-U, Tuohy's needle was introduced through the USG predetermined insertion point and epidural space was located using the LOR technique. USG increased the success rate of epidural at first attempt from 51.6% in group "L" to 87% in group "U." Fewer needle attempts (P-value - 0.001) were required in group "U" as compared to group "L." No accidental dural puncture in group-U, compared to 2 in group-L. Mean Depth of epidural space (cm) ultrasound depth (UD) = 3.89 ± 0.45 cm and needle depth (ND) = 4.05 ± 0.37 cm. Side effects profile in the ultrasound group was better. Preprocedural ultrasonography is a simple safe, accurate tool with less number of attempts to determine the needle insertion site, decrease the incidence of accidental dural punctures, and assess epidural space depth in parturients.

6: Pre-procedural ultrasonography as an adjunct to landmark technique for identification of epidural space in parturients coming for labour analgesia- a prospective randomised controlled trial.

Background and Aims:Pregnancy-induced softening of tissues and ligaments, may increase the false-positive rate when identifying the epidural space by the loss of resistance ( LOR ) technique. Ultrasonography (USG), which has now become the EYE of anesthesiologists, can be used as a reliable tool to facilitate epidural needle placement in parturients. The objectives of the study included finding out the correlation between USG guided estimated depth versus actual depth of epidural space in parturients.Number of attempts taken and incidence of dural punctures by landmark technique versus USG guided technique were the secondary objectivesMethods:After the approval from the institutional ethics committee and Clinical Trials Registry of India registration, 62 parturients of American Society of Anesthesiologists(ASA) II requesting labor analgesia were randomised into two groups of 31 each- GROUP-L (conventional landmark technique) and GROUP-U (preprocedural ultrasound scan done before epidural).In group-U, Tuohy needle was introduced through the USG pre-determined insertion point and epidural space was located using LOR technique.Results:Ultrasound increased the success rate of epidural at first attempt from 51.6% in group “L” to 87% in group “U” Fewer needle attempts (P value - 0.001) were required in group “U” as compared to group “L”.No accidental dural punctures in group U, compared to 6 in group-L.Mean depth of epidural space (cm)-UD= 3.89 ± 0.45 cm and ND=4.05±0.37 cm. Conclusion:Pre-procedural ultrasonography is a simple, safe and accurate tool to determine the needle insertion site, decrease the incidence of accidental dural punctures and helps to assess epidural space depth in parturients.Group LGroup U P Mean of total no. of attempts1.73±0.891.13±0.590.001No. of attempts First attempt16 (51.6%)27 (87%)0.002 Second attempt10 (32.2%)4 (12.9%) >2 attempts5 (16.1%)0Accidental dural puncture60

Correlation of preprocedural ultrasound estimated epidural depths in transverse median and posterior sagittal oblique view and body mass index with procedural epidural depths in patients scheduled for surgery under lumbar epidural anaesthesia.

Background and Aims:Preprocedural lumbar ultrasound (US) is employed for the estimation of epidural depth (ED). This study observed the correlation of preprocedural ED in transverse median (TM), parasagittal oblique (PSO) view, and body mass index (BMI) with procedural ED.Methods:In a prospective study, 100 female patients, aged 40–65 years, with American Society of Anesthesiologists physical status I/II, BMI 18.5–30 kg m−2 scheduled for surgeries under lumbar epidural blocks were included. In the TM group, preprocedural ultrasonography (USG) was performed in TM view and ED was calculated, whereas in the PSO group, the paramedian sagittal view was used and corresponding markings were done for epidural needle insertion in the midline and paramedian planes, respectively. The primary outcome was the correlation of procedural ED and preprocedural ED in TM and PSO views, respectively. The secondary outcomes included correlation of procedural ED with BMI, comparability of preprocedural, and procedural ED in TM and PSO views. Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) v19.0 (International Business Machines, USA).Results:The preprocedural and procedural ED was less in the TM group (4.43 ± 0.75 and 4.44 ± 0.75 cm) in comparison to those in the PSO group (4.86 ± 0.53, 4.90 ± 0.54; P = 0.001). Strong correlation was observed in preprocedural and procedural ED [r2 = 0.996 and 0.995]. The procedural ED had strong correlation with BMI [r2 = 0.600, P = 0.001] in the TM group, and weak correlation [r2 = 0.367] in the PSO group [P = 0.01]. The procedural ED was comparable to preprocedural ED in TM and PSO groups.Conclusion:Preprocedural US scanning provides an accurate estimate of actual EDs in TM and PSO view.

Correlation of skin epidural distance and posterior epidural space depth with age, weight, height, BMI, abdominal girth and position of the patient: A prospective randomised study

Lumbar epidural block is a commonly used procedure for providing anaesthesia, post-operative analgesia in all groups of patients irrespective of age, sex, weight and height of the patients. The knowledge of posterior space is important in view of the fact that this is the space where drugs for epidural anaesthesia/ analgesia are used. The knowledge of variability of this space with physical parameters of the patient, help us in reducing the incidence of total spinal anaesthesia.Two hundred adult patients in the age group of 20-60 years requiring subarachnoid block were chosen for the study. Using 22G Quincke spinal needle, epidural space was identified and skin epidural distance was measured. Proceeding the spinal needle further, causes needle to lie in subarachnoid space. The skin subarachnoid distance was measured. The difference between skin-subarachnoid distance and skin epidural distance denoted the posterior epidural space width. Its correlation with physical parameters was studied.Mean skin epidural distance was 4.30 ±0.57 in lateral position and 4.05 ± 0.57 in sitting position, the difference being statistically significant. (P= 0.002). There was positive correlation between skin epidural distance with weight, BMI and abdominal girth of the patient. Mean posterior epidural space depth was 0.468+14 cm in lateral position and 0.459+0.14 cm in sitting position, the difference being statistically insignificant. There was a positive correlation between posterior epidural space depth and height of the patient.The skin epidural distance varies with weight, BMI, abdominal girth and position of the patient. The posterior epidural space depth varies with the height of the patients.

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.

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. Eighty parturients with a body mass index > 30kg∙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. 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 - 0.29cm [95% limit of agreement, - 0.52 to - 0.05]. 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.

Accuracy of the SpineNav3DTM Ultrasound Technology in Estimating the Epidural Space Depth for Epidural and Spinal Insertion in Pregnant Obese Patients

Introduction: Ultrasound facilitates neuraxial puncture in obese parturients. Unfortunately, the widespread adoption of neuraxial ultrasound may be limited by the lack of technical expertise or the limited availability of the equipment. A wireless portable ultrasound device (Accuro, Rivanna Medical, Charlottesville, VA) with automated pattern recognition software (SpineNav3DTM technology) has been introduced to obtain the automated real-time identification of interspaces and epidural depth. The primary objective of this study was to assess the accuracy of the SpineNav3DTM ultrasound technology (Accuro) in estimating the epidural space depth compared to the standard ultrasound examination in pregnant obese patients. The secondary aim was to compare the ultrasound measurements with the measured needle depth during epidural and spinal insertion. Methods: The study was conducted at S Gerardo Hospital, Monza, Italy from March 2021 to April 2021. Obese laboring women requesting epidural analgesia or undergoing elective cesarean delivery under spinal anesthesia were recruited. All the subjects had their lumbar area scanned for the measurements of the depth of the epidural space by the SpineNav3DTM ultrasound technology and by the standard US and then both compared with the needle insertion depth in a double-blind fashion. Results: Forty-eight women were enrolled in the study. There was agreement (±0.25 cm) between the epidural depth (in cm) measured with the Accuro, versus the standard ultrasound. There was a significant difference between the mean depth of epidural space s measured by Accuro or Standard US and needle insertion depth (P Conclusions: The handheld ultrasound system with 3D spine navigation technology can automatically identify and measure the epidural depth with the same accuracy as the standard ultrasounds in obese pregnant women.

To Study the Correlation between Estimated Ultrasound Depth and Actual Needle Depth of Epidural Space in Transverse Plane in Parturients Undergoing Cesarean Section

Background and aim: During pregnancy, edema and obesity obscure the anatomical landmark and because of this epidural space identification become difficult by conventional methods. Loose connective tissue also causes false loss of resistance and responsible for failed block and complications. This study was planned for USG (ultrasonography) guided puncture point detection and epidural space depth assessment and its correlation with actual needle insertion depth in obstetric patients. Methods: Sixty four patients of ASA I and II for elective caesarean sections were included in this study. Lumbar space was identified by USG in which ligamentum-flavum with dura mater complex was taken as key structure for assessment of Ultrasound Depth (UD). This was followed by epidural needle insertion at the same marked point and measurement of epidural space Needle Depth (ND) taken. Concordance correlation coefficient and Bland Altman test were used to compare UD and ND. Results: Mean ND and UD were respectively 3.63 ± 043 cm and 3.61 ± 0.17 and these distances were not significantly different (P>0.0001). Bland Altman analysis showed mean of difference between UD and ND to be insignificant (0.02). Significant concordance correlation r=0.96 (95% CI-0.94-0.9, p>0.0001) was observed between ND and UD. Conclusion: In obstetric population pre puncture ultrasound scanning of lumbar spine helps in approximate assessment of epidural space depth and its correlate precisely with actual needle depth.

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.

Correlation of distance from skin to lumbar epidural space with age and height of patients

Background: Epidural block is a popular and versatile procedure with applications as sole anaesthetic, as an analgesic adjuvant to general anaesthesia and for post-operative analgesia in procedures involving lower limbs, perineum, pelvis, abdomen and thorax. However, success of the epidural technique depends upon the correct identification of epidural space. The knowledge of distance from skin to epidural space can help in better identification of epidural space and epidural catheter placement with fewer incidences of complications. We conducted a study to find the distance from skin to the epidural space and its correlation with patient height and age to improve the success rate. Methods: Seventy-four patients scheduled to undergo lower lumbar surgeries where epidural block was required as anaesthetic or analgesic, were included in the study. These patients were randomly divided into four different groups of 37 patients each according to their age (group A and group B) and height (group C and group D). In these patient’s epidural block was given by standard technique according to the need of surgery and epidural depth measured. Obtained results were compared among group A, B and group C, D depending on their age and height respectively. Results: In group A (age 20-30 years), mean epidural depth was 3.96±0.4 cm while in group B (age 30-40 years) mean epidural depth was 4.05±0.5 centimeters. In group C (height 155-169 cm) mean epidural depth was 3.88±0.4 centimeters while it was 4.13±0.5 centimeters in group D (height 170-184 cm).Conclusions: There was increase in epidural depth with increase in height of patients but there was no correlation between age of patients and epidural depth.