Anesthetic Spread Research Articles

Intra-abdominal pressure, vertebral column length, and spread of spinal anesthesia in parturients undergoing cesarean section: An observational study.

BackgroundIn parturients with increased physiologically intra-abdominal pressure (IAP) and a short stature, a greater cephalad spread of spinal anesthesia is often observed after a fixed amount of plain bupivacaine is administered. Therefore, we designed this prospective study to test whether IAP and vertebral column length (VCL) were predictors of spinal spread in parturients undergoing a cesarean section.MethodsA total of 113 parturients, all undergoing elective cesarean sections with single-shot spinal anesthesia, were enrolled. The L3-L4 interspace was entered, and 2 mL of 0.5% plain bupivacaine was injected into the subarachnoid space. Upon loss of temperature sensation at the T4 level, IAP was measured through a bladder catheter while the patient was in the supine position with a 10°left lateral tilt. Parturient demographic variables, including age, height, weight, IAP, and VCL were recorded. Linear regressions and multiple regressions were performed to analyze the relationships between parturient variables and the spread of spinal anesthesia.ResultsA total of 109 parturients were included in the analysis. Linear regression analysis showed a significant univariate correlation of height, weight, body mass index (BMI), IAP, and VCL with cephalad spread (all P< 0.004). Multiple linear regression analysis showed that IAP and VCL were the key determinants of spinal spread (both P < 0.0001), where as exclusion of age, weight, and height did not change the result (all P> 0.209).ConclusionsOur data indicated that IAP and VCL were significant predictors of intrathecal spread of plain bupivacaine, and there was a positive association between IAP and abdominal girth in term parturients.

The Role of Thoracolumbar Fascia in Planar Spread of Quadratus Lumborum Blocks

Injections of local anesthetic in the fascial planes around the quadratus lumborum muscle (QL blocks) are performed for postoperative pain control after abdominal surgeries. Multiple approaches of injecting anesthetic in and around the QL have been reported (anterior, posterior, transmuscular, intramuscular and lateral QL blocks). These techniques vary in terms of ease of administration and extent of analgesia. The extent of the anesthetic spread from this ultrasound‐guided procedure is influenced by the fascial layers surrounding the QL. A limited number of studies on small samples using varying amounts of anesthetic have left open questions regarding the extent of spread of local anesthetic and the best approach. This study evaluates the local anesthetic spread of two ultrasound‐guided lateral QL block approaches that have proven effective in controlling postoperative pain. A methylene blue‐dyed saline solution (40mL per QL block) is injected into fresh frozen cadavers (n=10). With the patient in supine position, the needle tip is placed at either (1) the anterolateral border of the QL deep to the transversalis fascia or (2) anterior to the transversus abdominus muscle superficial to its aponeurosis. Anatomic dissection of the injection plane is then performed to determine the extent of spread of the dyed saline. We hypothesize that the continuity between the transversalis fascia and the anterior layer of the thoracolumbar fascia (anterior to the QL) facilitates the cranial spread of the anesthetic under the lateral arcuate ligament to the endothoracic fascia. This would explain our observed analgesic effect past the umbilical region to dermatomes in the epigastric region (T7–T8). Understanding how QL fascial planes facilitate anesthetic spread will enable intraoperative administration of these blocks to be tailored to specific procedures and facilitate post‐operative recovery after abdominal operations. Improved methods of intraoperative pain management may reduce post‐operative opioid use and support the medical community in addressing the opioid epidemic in the United States.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Blocking around the transversalis fascia: behind the scene.

The transversalis fascia plane and the quadratus lomborum blocks target the branches of T12-L1 nerves and provide analgesia in patients undergoing surgery involving the corresponding dermatomes. The transversalis fascia is believed to contribute to determine the spread of local anesthetic in such blocks. Nonetheless, the anatomy of this fascia and its possible role in these blocks still have to be precisely defined. We conducted a series of 10 dissections and full-thickness specimens were obtained from one side for the microscopic analysis. Macroscopic study showed failed to identify a distinguishable fascial structure between the fascia of the transversus abdominis muscle and the peritoneum. Microscopic examination showed the presence of a further fascial layer (0.1-0.2 mm), ascribable to transversalis fascia. Transversalis fascia and transversus abdominis epimysium posteriorly diverge: transversus epimysium goes posteriorly to quadratus lomborum to joint the oblique internal aponeurosis, while transversalis fascia continues in front to quadratus lomborum. So, a little fascial triangle (2-3 mm) is formed on the lateral border of quadratus lomborum, defined by transversalis fascia and transversus abdominis. Inside this triangle, T12 and L1 nerves are present. Considering the thinness of the transversalis fascia and the small size of the triangular space that contains the target nerves, this is most likely a virtual, ideal rather than realistic injection site. Accordingly, it is probable that the local anesthetic is injected in the much wider retroperitoneal space and reaches the nerves by spreading backwards through the thin transversalis fascia.

Horner’s syndrome following obstetric neuraxial blockade – a systematic review of the literature

Horner’s syndrome is a rarely reported complication of neuraxial blockade. In obstetric practice, the neurological signs of Horner’s syndrome may cause anxiety amongst patients and healthcare staff, but more importantly may herald the onset of maternal hypotension. Medline, CINAHL, and EMBASE databases were searched to identify cases of Horner’s syndrome following obstetric neuraxial blockade. Anaesthetic technique, clinical features, anaesthetic management of the Horner’s syndrome and time to resolution were assessed. Seventy-eight case reports of Horner’s syndrome following obstetric neuraxial blockade were identified. Nine cases also had trigeminal nerve palsy and one case had hypoglossal nerve palsy. Amongst the 78 cases, 74% developed Horner’s syndrome within one hour of a local anaesthetic bolus. The median time for resolution of Horner’s syndrome was two hours, though one case was permanent. One case of Horner’s syndrome was found to be due to an internal carotid artery dissection. Some cases of Horner’s syndrome resolved spontaneously despite ongoing administration of epidural local anaesthetic. Hypotension was reported in 13%.Horner’s syndrome is usually a benign phenomenon, the consequence of high cephalad spread of local anaesthetic, that resolves spontaneously within a few hours. Patients with a persistent Horner’s syndrome, or one associated with atypical features such as neck pain, should undergo a diagnostic workup including magnetic resonance angiography of the neck. The dermatomal level of neuraxial blockade, maternal and fetal well-being should be taken into account when making decisions regarding neuraxial blockade. The presence of Horner’s syndrome alone should not lead to discontinuation of neuraxial blockade.

The ultrasound-guided retrolaminar block: volume-dependent injectate distribution.

PurposeThe ultrasound-guided retrolaminar block is one of the newer and simpler alternatives to the traditional, often technically challenging, paravertebral (PV) block. Its feasibility, safety, and efficacy have already been clinically demonstrated in patients with multiple rib fractures using higher volumes of local anesthetic, when compared with the traditional approach. The primary aim of this observational anatomical study was to assess the spread of local anesthetic from the retrolaminar injection point to the PV space and its volume dependence. Second, we assessed the incidence of epidural and contralateral PV spread in the both groups.MethodsTen fresh porcine cadavers were randomized into 2 groups (n=5 each) to receive ultrasound-guided retrolaminar injections at Th4-Th5 level with either 10 mL (low-volume group) or 30 mL (high-volume group) of 2% lidocaine and methylene blue mixture. After the procedure, the cadavers were dissected and frozen. Cross-section cuts (~1 cm thick) were performed to evaluate the injectate spread.ResultsIn the high-volume group, injectate spread from the retrolaminar to the PV space was observed in all specimens (5 out of 5; 100%), while in the low-volume group, no apparent spread to the PV space was found (0 out of 5; 0%). No epidural or contralateral PV spread was observed in any of the specimens.ConclusionFollowing ultrasound-guided retrolaminar injections in fresh porcine cadavers, injectate spread from the retrolaminar tissue plane to the PV space is strongly volume dependent, suggesting that, clinically, high local anesthetic volumes maybe critical for achieving regional anesthesia and analgesia consistent with traditional PV blockade.

The Analgesic Effect of Ultrasound-Guided Quadratus Lumborum Block After Cesarean Delivery: A Randomized Clinical Trial.

Landmark and ultrasound-guided transversus abdominis plane blocks have demonstrated an opioid-sparing effect postoperatively after cesarean delivery. The more posterior quadratus lumborum (QL) might provide superior local anesthetic spread to the thoracolumbar fascia and paravertebral space. The aim of our study was to evaluate the efficacy of the QL block after cesarean delivery. A randomized, double-blind, controlled trial was performed. Forty parturients undergoing cesarean delivery received bilateral ultrasound-guided QL blocks with either 2 mg/mL ropivacaine or saline postoperatively. All patients received spinal anesthesia with bupivacaine and sufentanil and a postoperative analgesic regimen of paracetamol, ibuprofen, and ketobemidone administered by a patient-controlled analgesic pump. The ketobemidone consumption and time of each dose administered were recorded. The primary outcome was ketobemidone consumption during the first 24 hours postoperatively. Secondary and exploratory analyses compared repeated measures of pain scores, nausea, and fatigue, and total differences in time until patients were able to stand and able to walk 5 m, and the interaction between the effective analgesic score and time. All 40 patients completed the trial, 20 in each group. The cumulative ketobemidone consumption in 24 hours was reduced in the active group compared with the control group (P = .04; ratio of means = 0.60; 95% confidence interval, 0.37-0.97). The effective analgesic scores were significantly better in the treatment group compared with the placebo group both at rest (P < .01) and during coughing (P < .01). QL block with ropivacaine reduces the postoperative ketobemidone consumption and pain intensity as a part of a multimodal analgesic regimen that excludes neuraxial morphine.

Hip/Shoulder Width Ratio Alters the Spread of Spinal Anesthesia: A Prospective Observational Study

Introduction: Many factors have been tested to predict the spread of spinal anesthesia in clinical practice. In the study, we aimed to investigate the correlation between hip/shoulder width ratio and spread of spinal anesthesia. Method: Sixty patients were enrolled in this study to determine the correlation between hip/shoulder width ratio and the spread of spinal anesthesia. The L4-L5 interspace, navigated by ultrasonography, was introduced at the lateral position with a 25G spinal needle. 3ml 0,5% hyperbaric bupivacaine was injected intrathecally in 15 seconds. Age, height, weight, body mass index, hip/shoulder width ratio, and vertebral column length were recorded. Spinal anesthesia spread was assessed at 0, 5, 10, 20, and 30 minutes after spinal anesthesia. The patient was turned supine 5 minutes after intrathecal injection. Multiple linear regression analysis was used to analyze the correlation between the spread of spinal anesthesia and age, height, weight, hip/shoulder width ratio, vertebral column length. Results: The study was completed without dropout and sixty participants were included in the analysis. There was a strong correlation between the spread of spinal anesthesia and hip/shoulder width ratio (r=0,766; p

Erector spinae plane block as an alternative to epidural analgesia for post-operative analgesia following video-assisted thoracoscopic surgery: A case study and a literature review on the spread of local anaesthetic in the erector spinae plane.

Post-operative pain after minimally invasive video-assisted thoracoscopic surgery (VATS) in adults is commonly managed with oral and parenteral opioids and invasive regional techniques such as thoracic epidural blockade. Emerging research has shown that the novel erector spinae plane (ESP) block, can be employed as a simple and safe alternative analgesic technique for acute post-surgical, post-traumatic and chronic neuropathic thoracic pain in adults. We illustrate this by presenting a paediatric case of VATS, in which an ESP block provided better analgesia, due to greater dermatomal coverage, as well as reduced side-effects when compared with a thoracic epidural that had previously been employed on the same patient for a similar procedure on the opposite side.

Correlation between Weight of the Baby and the Level of Sensory Blockade in Spinal Anaesthesia for Caesarean Section: An Observational Study.

Background:The spread of local anaesthetics during spinal anaesthesia is affected by various factors and can be unpredictable especially in parturients undergoing caesarean section. Factors like abdominal girth, symphysis fundal height etc have to studied to know their impact on level of sensory blockade. We hypothesized a study to find any correlation between weight of the baby and the level of sensory blockade.Methods:46 parturients posted for elective caesarean section belonging to American Society of Anaesthesiologists (ASA) physical status 1 and 2 were included in the study. Maternal height and weight were noted down before entering operation theatre. All patients were instituted subarachnoid block with 2 cc of 0.5% of hyperbaric bupivacaine in sitting position. Level of sensory blockade was assessed with pin prick along midline of the patient every min till 5th minute and 5 minutes till 15th minute. The birth weight of baby was recorded soon after delivery.Results:The weight of the baby and height of the mother were correlated with the sensory blockade of T4. The number of babies weighing more than 3.5 kgs were 3 in our study out of which 2 babies were associated with maximum sensory blockade at 15th minute. It amounts to 66.7% when compared with 14.7% in babies weighing 2.5 to 3.5 kgs which is suggestive of significance ('P' value of 0.093).Conclusion:There is no statistically significant correlation between weight of the baby and the level of sensory blockade.

Ultrasound-guided pudendal nerve block in children: A new technique of ultrasound-guided transperineal approach.

Transperineal pudendal nerve block guided by nerve stimulator is used in pediatric anesthesia as an alternative to caudal analgesia in perineal surgery. The risk of rectal puncture or intravascular injection is inherent to this blinded technique. We described a new technique of transperineal pudendal nerve block, with ultrasound guidance, to improve safety of the technique. The first goal of this study was to describe this new technique and to test its feasibility. The second objective was to evaluate intra operative effectiveness and postoperative pain control. After parental and children consent, this prospective descriptive study included children aged 1-15 years, ASA status I-III, scheduled for general anesthesia associated with bilateral pudendal nerve block for an elective perineal surgery. After standardized general anesthesia, the anesthesiologist performed pudendal nerve block under ultrasound guidance with "out of plane" approach and evaluated the visualization of anatomical structures (ischial tuberosity, rectum, and pudendal artery), of the needle and of the local anesthetic spread. Pudendal nerve block failure was defined as an increase in mean arterial blood pressure or heart rate more than 20% compared to baseline values after surgical incision. In the postoperative period, the need for rescue analgesia was noted. During the study period, 120 blocks were performed in 60 patients, including 59 boys. Quality of the ultrasonographic image was good in 81% of blocks, with easy visualization of ischium and rectum in more than 95% of cases. Localization of the tip of the needle was possible for all pudendal nerve blocks, directly or indirectly. The spread of local anesthetic was seen in 79% of cases. The block was effective in 88% of cases. The new technique of ultrasound-guided pudendal nerve block, described in this study, seems to be easy to perform with a good success rate, and probably improves safety of the puncture and of the injection by real-time visualization of anatomical structures and local anesthetic spread.

Abdominal girth and dorso-sacral distance can be used to estimate lumbosacral cerebral fluid volume.

Patients' abdominal girth and vertebral column length are highly correlated with the spread of local anaesthetics after spinal anaesthesia. Lumbosacral cerebrospinal fluid volume is the primary determinant for spinal spread. Thus, we attempted to verify the hypothesis that abdominal girth and dorso-sacral distance are correlated with lumbosacral cerebrospinal fluid volume. Forty-five healthy volunteers were enrolled in this study to measure lumbosacral cerebrospinal fluid volume using magnetic resonance imaging. The age, height, weight, abdominal girth, dorso-sacral distance and lumbosacral cerebrospinal fluid volume of the volunteers were recorded. Multiple linear regression analysis was used to analyse the correlation between age, height, weight, abdominal girth, dorso-sacral distance and lumbosacral cerebrospinal fluid volume. Two volunteers were excluded because of lumbar disc herniation, leaving 43 volunteers for analysis. Multiple linear regression analysis showed a strong correlation between abdominal girth, dorso-sacral distance and lumbosacral cerebrospinal fluid volume (both P < 0.01). The adjusted R2 was 0.644. Volunteers with small abdominal girth showed clear images of cerebrospinal fluid in the nerve root cuff at the intervertebral foramen in the three-dimensional magnetic resonance imaging reconstruction of lumbosacral cerebrospinal fluid, while the images were vague in volunteers with large abdominal girth. Clearer images implied larger lumbosacral cerebrospinal fluid volume, while vaguer images, smaller lumbosacral cerebrospinal fluid volume. Multiple regression analysis revealed that abdominal girth and dorso-sacral distance were correlated with lumbosacral cerebrospinal fluid volume. Smaller abdominal girths and larger dorso-sacral distances predict larger lumbosacral cerebrospinal fluid volume.

ED50 of intrathecal ropivacaine for cesarean section under prophylactic infusion of phenylephrine: A consort study.

Background:Studies have reported that prophylactic continuous infusion of phenylephrine during spinal anesthesia for cesarean section can decrease the spread of local anesthetics. We investigated the ED50 of intrathecal hyperbaric ropivacaine in parturient women undergoing cesarean section under prophylactic infusion of phenylephrine.Methods:Sixty parturient women were allocated into 2 groups in this prospective study. Group P received 0.5 mL kg−1 h−1 of phenylephrine (5 mg/50 mL) at the start of intrathecal injection, and Group C (control group) received the same volume of saline. The dose of intrathecal ropivacaine for each subject was decided through up-down allocation method. The initial dose was set as 7.5 mg. Successful anesthesia was defined as the level of T6 or above achieved within 15 minutes after intrathecal injection and no additional epidural drug or venous analgesia to complete operation. The Massey formula was applied to calculate the ED50 of intrathecal ropivacaine in both groups.Results:The ED50 of hyperbaric ropivacaine determined by up-and-down method was 7.2 mg (95% confidence interval (CI), 6.8–7.6 mg) in the Group P, and 6.8 mg (95% CI, 6.4–7.2 mg) in the Group C, there was significant difference between the 2 groups (P < .5). The ED50 of intrathecal ropivacaine increases compared with Group C when phenylephrine is prophylactic infused to prevent spinal induced hypotension in cesarean section.Conclusion:The ED50 of intrathecal hyperbaric ropivacaine is 7.2 mg when phenylephrine is prophylactic infused to prevent spinal induced hypotension in cesarean section, and more ropivacaine demands on spinal anesthesia for cesarean section (www.chictr.org.cn, registration number: ChiCTR-RIC-17011650).

Surgical placement of rectus sheath catheters in a cadaveric cystectomy model.

Introduction Surgically inserted rectus sheath catheters (RSCs) are used increasingly for analgesia after cystectomy and other abdominal surgery. Currently, there is little information on the optimal positioning of RSCs to allow maximal spread of local anaesthetic. This study sought to assess the spread of dye injected via RSCs and to highlight the extent of its coverage in a fresh unembalmed cadaveric cystectomy model in order to confirm the nerve endings that are likely to be anaesthetised with RSCs. Methods Four cadavers underwent lower midline incision with limited bladder mobilisation. A RSC was inserted into the eight hemiabdomens. The RSCs were positioned either anterior (n=5) or posterior to the rectus muscle (n=3). Dye was injected down the RSCs to evaluate spread. The eight hemiabdomens were dissected anatomically to determine the surface area of dye spread and nerve root involvement. Results The mean surface area of dye spread with anteriorly placed RSCs was 30.6cm2 anterior and 25.9cm2 posterior to the rectus muscle. The mean surface area of dye spread with posteriorly placed RSCs was 11.3cm2 anterior and 37.3cm2 posterior to the rectus muscle. The mean number of nerve roots stained with anteriorly and posteriorly placed RSCs was 3.8 and 2.7 respectively. Subcutaneous spread of dye was seen with one anterior RSC insertion. Peritoneal spread was seen with one anteriorly positioned RSC. Conclusions This study has demonstrated efficient nerve root infiltration with anteriorly and posteriorly positioned RSCs. It appears that dye spreads between the fibres of the rectus muscle rather than out laterally to the nerve roots when spreading from its initial compartment.

Ultrasound-Guided Posterior Femoral Cutaneous Nerve Block: A Cadaveric Study.

To identify any anatomic barriers to local anesthetic spread between the sciatic nerve (SN) and the posterior femoral cutaneous nerve (PFCN) at the level of the infragluteal crease and to describe a potential technique for an ultrasound (US)-guided subgluteal PFCN block in a cadaveric model. Bilateral US-guided subgluteal injections of a colored latex solution were performed around the SN (15 mL) and PFCN (10 mL) in 4 unembalmed cadavers, for a total of 8 cadaver thighs. The specimens were dissected after latex polymerization to observe the spread of the latex solutions. With US guidance, the PFCN was visualized deep to the gluteus maximus and slightly superficial or lateral to the SN at the level of the infragluteal crease. The SN and PFCN were found on dissection to be coated with their respective colored latex in all 8 thighs. The SN and PFCN were consistently separated by the deep investing muscular fascia of the thigh, with only 2 thighs showing substantial mixing of latex injectates. The deep investing muscular fascia of the thigh appears to impede the spread of injectate between the SN and PFCN in a most unembalmed cadaver specimens. A US-guided subgluteal PFCN blockade may be a feasible technique to complement an SN block when complete anesthesia of the posterior thigh is required.

Sonographic Guidance for Supraclavicular Brachial Plexus Blocks: Single vs. Double Injection Cluster Approach

Background: The cluster approach for supraclavicular brachial plexus block (SC-BPB) can be easily performed but may result in asymmetric local anesthetic (LA) spread. The authors hypothesized that the use of a cluster approach in each of the 2 planes would achieve better 3-dimensional LA distribution than the traditional single cluster approach. Objectives: The purpose of the present study was to compare a double injection (DI) in 2 planes (one injection in each plane) with the traditional single injection (SI) cluster approach for ultrasound-guided SC-BPB. Study Design: A randomized, controlled trial. Setting: Department of Anesthesiology and Pain Medicine, Gachon University Gil Medical Center. Methods: In the SI group (n = 18), 30 mL of LA was injected into the main neural cluster after penetrating the brachial plexus sheath laterally. In the DI group (n = 18), the needle penetrated the sheath in a downward direction at the first skin puncture, and 15 mL of LA was injected, and at the second skin puncture (behind the initial puncture site), the needle penetrated the sheath in an upward direction, and 15 mL was again injected. Ultrasound-guided SC-BPB was evaluated from immediately after the block every 5 minutes to 30 minutes by sensory and motor testing. The main outcome variables were procedural time; onset time (time for complete sensory and motor block of the median, radial, ulnar, and musculocutaneous nerves); and rate of blockage of all 4 nerves. Results: Procedure times (medians [interquartile range]) were similar in the DI and SI groups (5.5 [4.75 – 8] vs. 5 [4 – 7] minutes, respectively; P = 0.137). Block onset time in the DI group was not significantly different from that in the SI group (10 [5 – 17.5] vs. 20 [6.25 – 30] minutes, P = 0.142). However, the rate of blockage of all 4 nerves was significantly higher in the DI group (94% vs. 67%, P = 0.035). Limitations: Although the results of this study indicate LA distribution in the DI group was more evenly spread within brachial plexus sheaths than in the SI group, this was not confirmed by ultrasonography or contrast radiography. Conclusion: The DI approach can be performed easily as single cluster approach and increases the consistency of ultrasound-guided SC-BPB over the SI approach in terms of the rate of blocking of all 4 nerves

Abdominal girth and vertebral column length aid in predicting intrathecal hyperbaric bupivacaine dose for elective cesarean section.

Currently, there is no consensus on how to determine the optimal dose of intrathecal bupivacaine for an individual undergoing an elective cesarean section. In this study, we developed a regression equation between intrathecal 0.5% hyperbaric bupivacaine volume and abdominal girth and vertebral column length, to determine a suitable block level (T5) for elective cesarean section patients.In phase I, we analyzed 374 parturients undergoing an elective cesarean section that received a suitable dose of intrathecal 0.5% hyperbaric bupivacaine after a combined spinal-epidural (CSE) was performed at the L3/4 interspace. Parturients with T5 blockade to pinprick were selected for establishing the regression equation between 0.5% hyperbaric bupivacaine volume and vertebral column length and abdominal girth. Six parturient and neonatal variables, intrathecal 0.5% hyperbaric bupivacaine volume, and spinal anesthesia spread were recorded. Bivariate line correlation analyses, multiple line regression analyses, and 2-tailed t tests or chi-square test were performed, as appropriate. In phase II, another 200 parturients with CSE for elective cesarean section were enrolled to verify the accuracy of the regression equation.In phase I, a total of 143 parturients were selected to establish the following regression equation: YT5 = 0.074X1 − 0.022X2 − 0.017 (YT5 = 0.5% hyperbaric bupivacaine volume for T5 block level; X1 = vertebral column length; and X2 = abdominal girth). In phase II, a total of 189 participants were enrolled in the study to verify the accuracy of the regression equation, and 155 parturients with T5 blockade were deemed eligible, which accounted for 82.01% of all participants.This study evaluated parturients with T5 blockade to pinprick after a CSE for elective cesarean section to establish a regression equation between parturient vertebral column length and abdominal girth and 0.5% hyperbaric intrathecal bupivacaine volume. This equation can accurately predict the suitable intrathecal hyperbaric bupivacaine dose for elective cesarean section.

Electric Nerve Stimulation Does Not Correctly Predict Needle-Nerve Distance and Potential Local Anesthetic Spread for Interscalene Brachial Plexus Blockade.

This study evaluated electric nerve stimulation as a nerve location tool. After eliciting motor response in 43 patients undergoing shoulder surgery, the needle tip's position, distance from the closest nerve, and spread of saline were evaluated using ultrasound imaging. The needle's tip resided 1 to 4 mm from the closest nerve in 21, in direct contact with it in 7, and 6 to 18 mm away in 15 patients. In 21 patients, subsequent saline dissection did not reach the brachial plexus. Thus, the success rate of electric nerve stimulation for correct needle-nerve distance identification was 48.8%, with correct fluid spread reached in only 51.2% of patients.

Does the approach influence the success rate for ultrasound-guided rectus sheath blocks? An anatomical case series

The anterior cutaneous branches of the thoracolumbar spinal nerves enter the rectus sheath at its lateral border and perforate the muscle after travelling a short distance in the ventral direction. In this anatomical case series, we show that dye injection at the medial margin did not lead to reliable impregnation of the target nerves. The local anesthetic should therefore be injected at the lateral edge of the rectus sheath. Preceding surgical procedures to the ventral abdominal wall may affect the craniocaudal spread of local anesthetic.

Body height and the spread of spinal anaesthesia for caesarean section: a prospective controlled trial.

No conclusive evidence exists on the effect of patient height on the spread of spinal anaesthesia. Our aim was to measure the ED50 and ED95 values of intrathecal ropivacaine in taller and shorter patients, and thus investigate the hypothesis that the spinal dose requirement in shorter patients is lower than that in taller patients undergoing caesarean section. In this study, 270 pregnant women were assigned to the taller (Group T) or shorter group (Group S) based on their heights. Subjects in both groups were further randomly assigned to one of nine subgroups based on the dosage of intrathecal isobaric ropivacaine to be administered (7, 8, 9, 10, 11, 12, 13, 14 or 15 mg respectively). The ED50 and ED95 values of ropivacaine were 9.24 mg and 13.36 mg in Group S, and 10.11 mg and 14.63 mg in Group T, with no inter-group difference (P = 0.886). There was a significant inter-group difference in the incidence of hypotension and the changes in mean arterial pressure after spinal anaesthesia using 15 mg ropivacaine. The dose of ephedrine administered in Group S was higher than that in Group T when 15 mg ropivacaine was administered (P = 0.031). The taller and shorter patients did not respond differently to modest intrathecal doses of ropivacaine. However, a larger dose of ropivacaine was associated with an increased incidence of hypotension in shorter patients compared to that in taller patients.

Relationship Between Central Obesity and Spread of Spinal Anesthesia in Female Patients.

Central obesity may be related to the spread of spinal anesthesia in female patients. Fifty-seven female patients undergoing spinal anesthesia were allocated to either the central obesity or noncentral obesity group. After induction of spinal anesthesia, maximal sensory blockade (primary outcome), time for maximal sensory block, maximum motor block, time to maximum motor block, time to L2 regression, and time to Bromage scale 0 were evaluated. Multiple linear regression analyses showed that maximal sensory blockade was related to central obesity (P = .004). Central obesity is related to a more extensive spread of spinal anesthesia in female patients.