Kristopher M. Schroeder

Ultrasound-guided transversus abdominis plane block in the dog: an anatomical evaluation

OBJECTIVE To describe the ultrasound-guided technique to the transversus abdominis plane (TAP) block in the dog and evaluate the spread of a local anesthetic/methylene blue solution. STUDY DESIGN Prospective experimental trial. ANIMALS Ten adult Beagle cadavers weighing 11.1 ± 1.1 kg (mean ± SD). METHODS Transversus abdominis plane (TAP) blocks were performed bilaterally by a single trained individual on unpreserved cadaver dogs using 10 mL of methylene blue/bupivacaine solution per site. Dissection of the abdominal wall was performed within 15-55 minutes of block to determine distribution of injectate and nerve involvement in the transversus abdominis fascial plane. RESULTS The transversus abdominis fascial plane was adequately visualized via ultrasound and injected in twenty hemi-abdominal walls. Segmental branches of T11, T12, T13, L1, L2, and L3 were adequately stained in 20%, 60%, 100%, 100%, 90%, and 30% of injections, respectively. CONCLUSIONS AND CLINICAL RELEVANCE This anatomical study suggests that the transversus abdominis plane (TAP) block would provide adequate regional anesthesia of the abdomen, potentially extending to the cranial and caudal limits of the abdomen. This supports the clinical potential of this block in veterinary medicine.

A Comparison of Single-Shot Adductor Canal Block vs Femoral Nerve Catheter for Total Knee Arthroplasty.

Abstract The aim of this study was to compare perioperative analgesia provided by single-injection adductor canal block (ACB) to continuous femoral nerve catheter (FNC) when used in a multimodal pain protocol for total knee arthroplasty (TKA). A retrospective cohort study compared outcome data for 148 patients receiving a single-injection ACB to 149 patients receiving an FNC. The mean length of stay (LOS) in the ACB group was 2.67 (±0.56) and 3.01 days (±0.57) in the FNC group ( P P P =0.01). Single-injection ACB offered similar pain control and earlier discharge compared to continuous FNC in patients undergoing TKA.

The Perioperative Effect of Increased Body Mass Index on Peripheral Nerve Blockade: an Analysis of 528 Ultrasound Guided Interscalene Blocks

BACKGROUND AND OBJECTIVES Obese patients can pose a unique perioperative anesthetic challenge, making regional anesthetic techniques an intriguing means of providing analgesia for this population. Ultrasound guidance has been touted recently as being beneficial for this population in which surface landmarks can become obscured. In this study, the effect of increased Body Mass Index (BMI) on ultrasound guided interscalene peripheral nerve blockade is investigated. MATERIAL AND METHODS This study is a retrospective review of 528 consecutive patients who received preoperative ultrasound-guided interscalene nerve blocks at the University of Wisconsin Hospital and Clinics. We examined the association between BMI and the following parameters: time required for block placement; presence of Postoperative Nausea and Vomiting (PONV); postoperative Post Anesthesia Care Unit (PACU) pain scores; volume of local anesthetic injected; acute complications; and opioid administration preoperatively, intraoperatively, and postoperatively. Univariate and multivariate least squares and logistic regression models were used. RESULTS An elevated BMI was associated with an increased: time required for block placement (p-value=0.025), intraoperative fentanyl administration (p-value<0.001), peak PACU pain scores (p-value<0.001), PACU opioid administration (p-value<0.001), PACU oral opioid administration (p-value<0.001), total PACU opioid administration (p-value<0.001) and incidence of PACU nausea (p-value=0.025) CONCLUSIONS Ultrasound guided interscalene nerve blocks for perioperative analgesia can be safely and effectively performed in the obese patient but they may be more difficult to perform and analgesia may not be as complete.

The air-Q(®) intubating laryngeal airway vs the LMA-ProSeal(TM) : a prospective, randomised trial of airway seal pressure.

We performed a prospective, open‐label, randomised controlled trial comparing the air‐Q® against the LMA‐ProSeal™ in adults undergoing general anaesthesia. One hundred subjects (American Society of Anesthesiologists physical status 1–3) presenting for elective, outpatient surgery were randomly assigned to 52 air‐Q® and 48 ProSeal devices. The primary study endpoint was airway seal pressure. Oropharyngolaryngeal morbidity was assessed secondarily. Mean (SD) airway seal pressures for the air‐Q® and ProSeal were 30 (7) cmH2O and 30 (6) cmH2O, respectively (p = 0.47). Postoperative sore throat was more common with the air‐Q® (46% vs 38%, p = 0.03) as was pain on swallowing (30% vs 5%, p = 0.01). In conclusion, the air‐Q® performs well as a primary airway during the maintenance of general anaesthesia with an airway seal pressure similar to that of the ProSeal, but with a higher incidence of postoperative oropharyngolaryngeal complaints.

The analgesic impact of preoperative lumbar plexus blocks for hip arthroscopy. A retrospective review

This study aimed to examine the impact of preoperative lumbar plexus blockade on perioperative analgesia and opioid consumption following hip arthroscopy. The records of patients (n = 236) who underwent hip arthroscopy between July 27, 2004 and November 15, 2009 were reviewed (118 patients with preoperative lumbar plexus block and 118 procedure matched patients without a preoperative block). Baseline patient characteristics were similar between groups. Immediate post-anaesthesia care unit (PACU) pain scores, peak PACU pain scores, perioperative opioid administration, and PACU antiemetic administration favoured preoperative block placement. Postoperative modified Harris Hip scores and postoperative day one pain scores were similar between groups. Total hospital time following the surgical procedure was longer in the block group. While preoperative lumbar plexus blockade may be helpful for analgesia following hip arthroscopy, more research needs to be done to determine the ideal analgesic regimen for these patients.

Weight-Based Volume of Injection Influences Cranial to Caudal Spread of Local Anesthetic Solution in Ultrasound-Guided Transversus Abdominis Plane Blocks in Canine Cadavers

OBJECTIVE To determine if the volume of injected local anesthetic solution affects cranial to caudal spread when performing ultrasound-guided transversus abdominis plane (TAP) blocks in dogs. STUDY DESIGN Prospective experimental study. ANIMALS Adult Beagle cadavers (n = 20) METHODS Bilateral TAP blocks using ultrasound guidance was performed in 20 Beagle cadavers (mean ± SD weight, 9.3 ± 1.4 kg) using a 1:1 solution of methylene blue/bupivacaine injected at volumes of 0.25, 0.5, 0.75, and 1.0 mL/kg. Cadavers were dissected to determine injectate spread within the transversus abdominis fascial plane. RESULTS The transversus abdominis fascial plane was adequately identified by ultrasonography, injected, and dissected in 38 beagle hemi-abdominal walls; injectate was not identified in 2 hemi-abdominal walls. Dermatomal spread (number of ventral nerve roots saturated by injected solution) was volume dependent (P = .026, Kruskal Wallis): 2.9 ± 0.74 nerve roots for 0.25 mL/kg; 3.4 ± 1.1 for 0.5 mL/kg; 4.0 ± 0.67 for 0.75 mL/kg; and 4.2 ± 1.2 for 1 mL/kg. CONCLUSION In Beagle cadavers, the volume of injected local anesthetic solution significantly affects cranial to caudal spread within the TAP during ultrasound-guided TAP blocks. The volume of local anesthetic injected could potentially be used to augment the spread of analgesic coverage for a given surgical procedure in dogs.

Transversus abdominis plane block for exploratory laparotomy in a Canadian lynx (Lynx canadensis).

Abstract The transversus abdominis plane (TAP) block is an innovative regional anesthetic technique using local anesthetic that is gaining popularity in the analgesic management of human patients undergoing abdominal surgery. Needle placement in the TAP block is within the facial plane between the internal oblique and transversus abdominis muscles and involves the abdominal and thoracic nerves. Successful blockade generally involves spinal nerves T10–L1 and may induce sensory blockade as far cranially as T7, thus producing analgesia for abdominal surgery. Human studies suggest that this regional anesthetic technique may provide postoperative analgesia of the abdominal wall for up to 48 hr. Because of the extent and duration of sensory blockade, this novel technique with bupivacaine was used on a Canadian lynx (Lynx canadensis), possibly providing 8–10 hr of intra- and postoperative analgesia concurrent to exploratory laparotomy for removal of a gastric foreign body.

Teaching sonoanatomy to anesthesia faculty and residents: utility of hands-on gel phantom and instructional video training models

STUDY OBJECTIVE Thousands of patients worldwide annually receive neuraxial anesthesia and analgesia. Obesity, pregnancy, and abnormal spinal anatomy pose challenges for accurate landmark palpation. Further, spinal sonoanatomy is not uniformly taught in residency education, even though its use has previously been shown to improve identification of relevant structures and decrease procedural complications and failure rates. The aim of this study was to evaluate the use of hands-on gel phantom and instructional video training for teaching spinal sonoanatomy among anesthesiology faculty and residents. DESIGN Twenty-three residents and 27 anesthesiologists were randomized to gel phantom, video teaching, and control groups. SETTING Academic Hospital. MEASUREMENTS Successful identification of spinal sonoanatomy was attempted on a human volunteer before and immediately after the respective intervention and 3 weeks later. Perceived knowledge and training modality satisfaction were assessed using modified Likert scales. INTERVENTIONS Gel phantom and video teaching groups compared with control (no intervention). MAIN RESULTS Both interventions significantly improved spine sonoanatomy identification accuracy. Logistic regression analysis demonstrated both interventions improved the odds of transverse process (gel 12.61, P = .013; video 7.93, P = .030) and lamina (gel 65.12, P = .003; video 8.97, P = .031) identification. Perceived knowledge of basic spinal anatomy and spinal sonoanatomy improved in the intervention versus control groups. Mean (SD) modified Likert scale scores for learning satisfaction (1 = unsatisfied, 10= very satisfied) were 8.1 (1.5) and 8.0 (1.7) for hands-on gel phantom and instructional video training participants, respectively. CONCLUSION Use of hands-on gel phantom or instructional video training can improve anesthesia staff and resident knowledge of lumbar spine sonoanatomy.

Epidural anesthesia as a novel anesthetic technique for anterior lumbar interbody fusion

STUDY OBJECTIVE To determine if epidural anesthesia is a reasonable technique for anterior lumbar interbody fusion. DESIGN Retrospective chart review. SETTING Academic university hospital. MEASUREMENTS The charts of patients who underwent an anterior lumbar interbody fusion between January 1, 2001 and November 1, 2008 were reviewed. A total of 102 consecutive patients, of whom 19 received an epidural and 83 underwent general anesthesia, met inclusion criteria. Postoperative pain, nausea, opioid administration, operating room time, anesthesia time, Postanesthesia Care Unit (PACU) time, and total hospital time were compared. MAIN RESULTS In the PACU, patients receiving epidural anesthesia showed reductions in median immediate [numerical rating scale (NRS) 0 vs 7; P < 0.001] and peak (NRS 4 vs 8; P = 0.001) postoperative pain scores, and postoperative mean arterial pressure (69.7 vs 90.3; P < 0.001). Epidural anesthesia patients also needed significantly less intravenous morphine-equivalent medication both intraoperatively (5 vs 29; P < 0.001) and postoperatively (3.34 vs 10; P = 0.021). CONCLUSIONS Epidural anesthesia for anterior lumbar interbody fusion is potentially beneficial compared with general anesthesia, showing improved perioperative pain control.

An easily made, low-cost phantom for ultrasound airway exam training and assessment.

Background: Recent manuscripts have described the use of ultrasound imaging to evaluate airway structures. Ultrasound training tools are necessary for practitioners to become proficient at obtaining and interpreting images. Few training tools exist and those that do can often times be expensive and rendered useless with repeated needle passes. Methods: We utilised inexpensive and easy to obtain materials to create a gel phantom model for ultrasound-guided airway examination training. Results: Following creation of the gel phantom model, images were successfully obtained of the thyroid and cricoid cartilages, cricothyroid membrane and tracheal rings in both the sagittal transverse planes. Conclusion: The gel phantom model mimics human airway anatomy and may be used for ultrasound-guided airway assessment and intervention training. This may have important safety implications as ultrasound imaging is increasingly used for airway assessment.