Ki Jinn Chin

Use of Sonography for Airway Assessment An Observational Study

Objective. The purpose of this study was to evaluate the feasibility of sonography in identifying the anatomic structures of the upper airway and to describe their appearance on sonography. Methods. We enrolled 24 healthy volunteers, placed them supine with their head extended and neck flexed (the “sniffing” position), and performed a systematic sonographic examination of their upper airway from the floor of the mouth to the suprasternal notch. Results. We were able to visualize all relevant anatomic structures in all of the participants using either a linear or curved transducer oriented in 1 of 3 planes: sagittal, parasagittal, and transverse. Bony structures (eg, the mandible and hyoid) were brightly hyperechoic with an underlying hypoechoic acoustic shadow. Cartilaginous structures (eg, the epiglottis, thyroid cartilage, cricoid cartilage, and tracheal rings) were hypoechoic, and their intraluminal surface was outlined by a bright air‐mucosa interface. The vocal cords were readily visualized through the thyroid cartilage. However, the posterior pharynx, posterior commissure, and posterior wall of the trachea could not be visualized because of artifacts created by an intraluminal air column. Conclusions. Sonography of the upper airway is capable of providing detailed anatomic information and has numerous potential clinical applications.

The Erector Spinae Plane Block: A Novel Analgesic Technique in Thoracic Neuropathic Pain.

Abstract Thoracic neuropathic pain is a debilitating condition that is often poorly responsive to oral and topical pharmacotherapy. The benefit of interventional nerve block procedures is unclear due to a paucity of evidence and the invasiveness of the described techniques. In this report, we describe a novel interfascial plane block, the erector spinae plane (ESP) block, and its successful application in 2 cases of severe neuropathic pain (the first resulting from metastatic disease of the ribs, and the second from malunion of multiple rib fractures). In both cases, the ESP block also produced an extensive multidermatomal sensory block. Anatomical and radiological investigation in fresh cadavers indicates that its likely site of action is at the dorsal and ventral rami of the thoracic spinal nerves. The ESP block holds promise as a simple and safe technique for thoracic analgesia in both chronic neuropathic pain as well as acute postsurgical or posttraumatic pain.

Ultrasound Imaging Facilitates Spinal Anesthesia in Adults with Difficult Surface Anatomic Landmarks

Background:Poor surface anatomic landmarks are highly predictive of technical difficulty in neuraxial blockade. The authors examined the use of ultrasound imaging to reduce this difficulty. Methods:The authors recruited 120 orthopedic patients with one of the following: body mass index more than 35 kg/m2 and poorly palpable spinous processes; moderate to severe lumbar scoliosis; or previous lumbar spine surgery. Patients were randomized to receive spinal anesthetic by the conventional surface landmark-guided technique (group LM) or by an ultrasound-guided technique (group US). Patients in group US had a preprocedural ultrasound scan to locate and mark a suitable needle insertion point. The primary outcome was the rate of successful dural puncture on the first needle insertion attempt. Normally distributed data were summarized as mean ± SD and nonnormally distributed data were summarized as median [interquartile range]. Results:The first-attempt success rate was twice as high in group US than in group LM (65% vs. 32%; P < 0.001). There was a twofold difference between groups in the number of needle insertion attempts (group US, 1 [1–2] vs. group LM, 2 [1–4]; P < 0.001) and number of needle passes (group US, 6 [1–10] vs. group LM, 13 [5–21]; P = 0.003). More time was required to establish landmarks in group US (6.7 ± 3.1; group LM, 0.6 ± 0.5 min; P < 0.001), but this was partially offset by a shorter spinal anesthesia performance time (group US, 5.0 ± 4.9 vs. group LM, 7.3 ± 7.6 min; P = 0.038). Similar results were seen in subgroup analyses of patients with body mass index more than 35 kg/m2 and patients with poorly palpable landmarks. Conclusion:Preprocedural ultrasound imaging facilitates the performance of spinal anesthesia in the nonobstetric patient population with difficult anatomic landmarks.

Ultrasonography of the Adult Thoracic and Lumbar Spine for Central Neuraxial Blockade

The role of ultrasound in central neuraxial blockade has been underappreciated, partly because of the relative efficacy of the landmark-guided technique and partly because of the perceived difficulty in imaging through the narrow acoustic windows produced by the bony framework of the spine. However, this also is the basis for the utility of ultrasound: an interlaminar window that permits passage of sound waves into the vertebral canal also will permit passage of a needle. In addition, ultrasound aids in identification of intervertebral levels, estimation of the depth to epidural and intrathecal spaces, and location of important landmarks, including the midline and interlaminar spaces. This can facilitate neuraxial blockade, particularly in patients with difficult surface anatomic landmarks. In this review article, the authors summarize the current literature, describe the key ultrasonographic views, and propose a systematic approach to ultrasound imaging for the performance of spinal and epidural anesthesia in the adult patient.

Ultrasound-guided peripheral nerve blockade.

Purpose of review The use of ultrasound for peripheral nerve blockade is becoming popular. Although the feasibility of ultrasound-guided nerve blockade is now clear, it is uncertain at this time whether it represents the new standard for regional anesthesia in terms of efficacy and safety. Recent findings The ability to visualize nerve location, needle advancement, needle–nerve interaction, and local anesthetic spread makes ultrasound-guided nerve block an attractive option. Study results indicate that these advantages can improve the ease of block performance, block success rates, and complications. At the same time there is evidence that ultrasound-guided regional anesthesia is a unique skill in its own right, and that proficiency in it requires training and experience. Summary Ultrasound is a valuable tool that is now available to the regional anesthesiologist, and it is fast becoming a standard part of practice. It promises to be of especial value to the less experienced practitioner. Ultrasound does not in itself, however, guarantee the efficacy and safety of peripheral nerve blockade. Proper training in its use is required and we can expect to see the development of formal standards and guidelines in this regard.

Hand motion analysis using the imperial college surgical assessment device: validation of a novel and objective performance measure in ultrasound-guided peripheral nerve blockade.

Background and Objectives: The Imperial College Surgical Assessment Device (ICSAD) has been validated in various settings as an objective tool to measure technical performance. We sought to establish (1) the construct validity of the ICSAD as an assessment tool in ultrasound-guided supraclavicular block by determining its ability to discriminate between operators of different experience level and (2) the concurrent validity of the ICSAD by correlating it with a task-specific checklist and a global rating scale. Methods: We compared 30 performances of ultrasound-guided supraclavicular block by junior residents with 30 performances by highly experienced consultant anesthesiologists. We also studied 10 anesthesiologists undertaking a 1-year regional anesthesia fellowship and compared a performance in their first month to one in their last 3 months. We used the ICSAD to measure 3 dexterity parameters during the scanning and needling phases of each block: time taken, number of movements, and path length traveled by each hand. Two blinded expert observers evaluated video recordings of each block using a 30-item task-specific checklist and a 7-item global rating scale. Results: Consultants (experts) performed significantly better than residents (novices) on all ICSAD parameters in both scanning and needling phases. Fellows demonstrated improvement in all ICSAD parameters between their early and late performance, reflecting their transition from novice to expert. The task-specific checklist and global rating scale were also highly discriminating between novice and expert performances. There was excellent correlation between all 3 measurement tools, thereby establishing their concurrent validity. Conclusions: The ICSAD is both valid and useful in assessing performance of ultrasound-guided supraclavicular block.

Lumbar Neuraxial Ultrasound for Spinal and Epidural Anesthesia: A Systematic Review and Meta-Analysis.

Background This systematic review examines the evidence for preprocedural neuraxial ultrasound as an adjunct to lumbar spinal and epidural anesthesia in adults. Methods We searched MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases from inception to June 30, 2014, for randomized controlled trials (RCTs) and cohort studies that reported data answering one or more of the following 3 questions: (1) Does ultraound accurately identify a given lumbar intervertebral space? (2) Does ultrasound accurately predict the needle insertion depth required to reach the epidural or intrathecal space? (3) Does ultrasound improve the efficacy and safety of spinal or lumbar epidural anesthesia? Results Thirty-one clinical trials and 1 meta-analysis were included in this review. Data from 8 studies indicate that neuraxial ultrasound can identify a given lumbar intervertebral space more accurately than by landmark palpation alone. Thirteen studies reported an excellent correlation between ultrasound-measured depth and needle insertion depth to the epidural or intrathecal space. The mean difference between the 2 measurements was within 3 mm in most studies. Thirteen RCTs, 5 cohort studies, and 1 meta-analysis reported data on efficacy and safety outcomes. Results consistently showed that ultrasound resulted in increased success and ease of performance. Ultrasound seemed to reduce the risk of traumatic procedures but there was otherwise insufficient evidence to conclude if it significantly improves safety. Conclusions There is significant evidence supporting the role of neuraxial ultrasound in improving the precision and efficacy of neuraxial anesthetic techniques. Whats New We know that neuraxial ultrasound is a useful complement to clinical examination when performing lumbar central neuraxial blocks. It provides anatomical information including the depth of the epidural space, the identity of a given intervertebral level, and the location of the midline and interspinous/interlaminar spaces. This information can be used to successfully guide subsequent needle insertion. Since 2010, new data from RCTs and 1 meta-analysis suggest that neuraxial ultrasound increases the success and reduces the technical difficulty of lumbar central neuraxial blocks. Findings from the meta-analysis suggest that neuraxial ultrasound reduces the risk of traumatic procedures, and thus may possibly contribute to the safety of lumbar central neuraxial blocks.

The analgesic efficacy of pre-operative bilateral erector spinae plane (ESP) blocks in patients having ventral hernia repair.

Laparoscopic ventral hernia repair is an operation associated with significant postoperative pain, and regional anaesthetic techniques are of potential benefit. The erector spinae plane (ESP) block performed at the level of the T5 transverse process has recently been described for thoracic surgery, and we hypothesised that performing the ESP block at a lower vertebral level would provide effective abdominal analgesia. We performed pre‐operative bilateral ESP blocks with 20–30 ml ropivacaine 0.5% at the level of the T7 transverse process in four patients undergoing laparoscopic ventral hernia repair. Median (range) 24‐h opioid consumption was 18.7 mg (0.0–43.0 mg) oral morphine. The highest and lowest median (range) pain scores in the first 24 h were 3.5 (3.0–5.0) and 2.5 (0.0–3.0) on an 11‐point numerical rating scale. We also performed the block in a fresh cadaver and assessed the extent of injectate spread using computerised tomography. There was radiographic evidence of spread extending cranially to the upper thoracic levels and caudally as far as the L2–L3 transverse processes. We conclude that the ESP block is a promising regional anaesthetic technique for laparoscopic ventral hernia repair and other abdominal surgery when performed at the level of the T7 transverse process. Its advantages are the ability to block both supra‐umbilical and infra‐umbilical dermatomes with a single‐level injection and its relative simplicity.

The Erector Spinae Plane Block Provides Visceral Abdominal Analgesia in Bariatric Surgery: A Report of 3 Cases

Abstract Postoperative pain after bariatric surgery can be significant and yet difficult to manage. These patients frequently have associated obstructive sleep apnea and are at risk of respiratory depression with opioid analgesia. Abdominal wall blocks such as the subcostal transversus abdominis plane block are not of significant benefit, probably in part because they provide only somatic analgesia. The ultrasound-guided erector spinae plane (ESP) block is a recently described regional anesthetic technique for providing thoracic analgesia when performed at the level of the T5 transverse process. Local anesthetic injected into the fascial plane deep to the erector spinae muscle spreads in a craniocaudal fashion over several levels. Local anesthetic also penetrates anteriorly through the intertransverse connective tissue and enters the thoracic paravertebral space where it can potentially block not only the ventral and dorsal rami of spinal nerves but also the rami communicantes that transmit sympathetic fibers. Coupled with the fact that the erector spinae muscle and ESP extend down to the lumbar spine, this suggests that the ESP block could result in both visceral and somatic abdominal analgesia if the injection were performed at a lower thoracic level. We describe a series of 3 cases that illustrate the efficacy of bilateral ESP blocks performed at the level of the T7 transverse process for relieving visceral abdominal pain following bariatric surgery. Further investigation is recommended to establish the potential of the ESP block as an analgesic modality in abdominal surgery.

Ultrasonography of the lumbar spine for neuraxial and lumbar plexus blocks.

Purpose of review Ultrasonography of the spine has evolved into a well described technique that can be applied to facilitate neuraxial and lumbar plexus blockade. Recent findings There is increasing evidence for the clinical benefits of ultrasound imaging prior to administration of neuraxial blockade. Recent randomized controlled trials have shown that efficacy of epidural analgesia is improved, and the technical difficulty of spinal and epidural anaesthesia is reduced. Ultrasound imaging may also permit more accurate prediction of the depth to epidural and intrathecal spaces and more accurate identification of intervertebral levels. The use of ultrasound in lumbar plexus blockade has been described in the context of both preprocedural imaging and real-time needle guidance; however, its clinical benefit in this setting has not yet been clearly established. Summary Preprocedural ultrasound imaging of the spine may reduce the technical difficulty of neuraxial blockade and also improve clinical efficacy. Similar benefits are expected in the setting of lumbar plexus blockade although there is currently no evidence to confirm this. Real-time ultrasound-guided neuraxial and lumbar plexus blockade are challenging techniques that need further validation.