Stanley C. Yuan

A randomized crossover study comparing a novel needle guidance technology for simulated internal jugular vein cannulation.

Background:Despite ultrasound guidance for central line placement, complications persist, as exact needle location is often difficult to confirm with standard two-dimension ultrasound. A novel real-time needle guidance technology has recently become available (eZono, Germany) that tracks the needle during insertion. This randomized, blinded, crossover study examined whether this needle guidance technology improved cannulation of a simulated internal jugular (IJ) vein in an ultrasound phantom. Methods:One hundred physicians were randomized to place a standard needle in an ultrasound neck phantom with or without the needle guidance system. Video cameras were placed externally and within the lumens of the vessels to record needle location in real time. The primary outcome measured was the rate of posterior wall puncture. Secondary outcomes included number of carotid artery punctures, number of needle passes, final needle position, time to cannulation, and comfort level with this new technology. Results:The incidence of posterior vessel wall puncture without and with needle guidance was 49 and 13%, respectively (P < 0.001, odds ratio [OR] = 7.33 [3.44 to 15.61]). The rate of carotid artery puncture was higher without needle navigation technology than with needle navigation 21 versus 2%, respectively (P = 0.001, OR = 12.97 [2.89 to 58.18]). Final needle tip position being located within the lumen of the IJ was 97% accurate with the navigation technology and 76% accurate with standard ultrasound (P < 0.001, OR = 10.42 [2.76 to 40.0]). Average time for successful vessel cannulation was 1.37 times longer without guidance technology. Conclusion:This real-time needle guidance technology (eZono) shows significant improvement in needle accuracy and cannulation time during simulated IJ vein puncture.

Continuous ambulatory adductor canal catheters for patients undergoing knee arthroplasty surgery.

STUDY OBJECTIVE To determine after knee arthroplasty surgery the feasibility of discharging patients home on postoperative day 1 with continuous adductor canal blocks. DESIGN Retrospective case series. SETTING Outpatient setting after hospital discharge. PATIENTS Patients undergoing knee arthroplasty surgery from October 2013 to August 2014. INTERVENTIONS All patients received continuous adductor canal catheters for postoperative analgesia and were discharged to home on postoperative day 1. Continuous catheters were intended to remain intact in the ambulatory setting through postoperative day 3. MEASUREMENTS Data obtained included demographic information, duration of hospital stay, resting and active pain scores, opioid utilization, opioid-induced adverse effects, complications relating to the perineural catheter, and hospital readmissions. MAIN RESULTS Sixty-nine of 582 patients (11.9%) were discharged to home on postoperative day 1. The median numerical pain score after discharge with a continuous adductor canal block was ≤2 at rest and ≤4 with activity. After block discontinuation on postoperative day 4, median pain scores were the same. No patients reported any unintentional catheter dislodgements, falls, or dysesthesias. There were no readmissions of any patient in this cohort within 90 days of surgery. CONCLUSIONS Ambulatory adductor canal catheters are a feasible analgesic modality after knee arthroplasty surgery as pain scores remained low and adverse events were minimal.

Fluoroscopic evaluation of contrast distribution within the adductor canal.

Background and Objectives This case series assesses the in vivo spread of contrast within the adductor canal in subjects who recently underwent a total knee arthroplasty. A previous analysis of profound leg weakness with a continuous adductor canal revealed contrast spread from the adductor canal to the femoral triangle with as little as 2 mL of volume. Methods We enrolled 10 American Society of Anesthesiologists class II–III subjects. Maximum voluntary isometric contraction was measured to assess quadriceps strength before and after surgery. Contrast was then injected continuously via electronic pump into the adductor canal, and fluoroscopy was used to capture images after 1-mL increments. For analysis, the femur was divided into 8 equidistant sectors between the lesser trochanter and medial epicondyle. Results Contrast did not reach the level of the lesser trochanter or the medial epicondyle of the femur in any subject. The greatest spread after 5 mL of contrast was 4 sectors. Sixty percent of subjects had contrast spread within either the same sector as the catheter tip or 1 sector distally. No subjects demonstrated additional proximal spread of contrast after 4 mL. Conclusions This study reveals that in vivo continuous infusions within the adductor canal spread in both a cephalad and caudad direction in limited fashion. Although a previous report described proximal spread of injectate to the level of the common femoral nerve, this event is infrequent.

A Double-Blind Randomized Comparison of Continuous Interscalene, Supraclavicular, and Suprascapular Blocks for Total Shoulder Arthroplasty

Background and Objectives Continuous brachial plexus blocks at the interscalene level are associated with known diaphragm dysfunction from phrenic nerve paresis. More distal blocks along the brachial plexus may provide postsurgical analgesia while potentially having less effect on diaphragm function. Continuous interscalene, continuous supraclavicular, and continuous suprascapular nerve blocks were evaluated for respiratory function and analgesia after total shoulder arthroplasty. Methods After ethics board approval, subjects presenting for total shoulder arthroplasty were planned for randomization in a 1:1:1 ratio of a continuous interscalene, supraclavicular, or suprascapular block. The primary outcome was the assessment of vital capacity after 24 hours of continuous nerve block infusion (6 mL/h; 0.2% ropivacaine), without an initial bolus of local anesthetic during catheter placement. Additional outcomes included diaphragm excursion, pain scores, opioid consumption, and adverse effects. Results Seventy-five subjects, 25 per group, completed the study. At 24 hours of continuous infusion only (no initial block bolus), the mean vital capacity reduction in the continuous interscalene control group was 991 mL (95% confidence interval [CI], 820–1162). Compared to the interscalene group, the continuous supraclavicular group had a mean vital capacity reduction of 803 mL (95% CI, 616–991; P = 0.322). The continuous suprascapular group had a significantly improved mean vital capacity reduction of 464 mL (95% CI, 289–639; P < 0.001) when similarly compared against the interscalene group. A relative compromise in ultrasound-measured diaphragm excursion was identified in the interscalene group compared to both the supraclavicular group (P = 0.012) and the suprascapular group (P < 0.001). Mean pain scores on an 11-point scale (2.2, 1.6, and 2.6) and 24-hour opioid consumption (13.8 mg, 9.9 mg, and 21.8 mg) for groups interscalene, supraclavicular, and suprascapular, respectively, did not show statistically significant differences. Less adverse effects (Horner syndrome, dyspnea, and hoarseness) were noted in the suprascapular group when compared with the interscalene group (P = 0.002). Conclusions A continuous suprascapular block may be a useful analgesic alternative to the interscalene or supraclavicular approaches when the preservation of lung function is a priority after shoulder replacement surgery.

Evaluation of Ultrasound-assisted Thoracic Epidural Placement in Patients Undergoing Upper Abdominal and Thoracic Surgery: A Randomized, Double-blind Study.

Background and Objectives The placement of thoracic epidurals can be technically challenging and requires a thorough understanding of neuraxial anatomy. Although ultrasound imaging of the thoracic spine has been described, no outcome studies on the use of this imaging have been performed. We evaluated whether preprocedural ultrasound of the thoracic spine would facilitate the process of epidural catheterization. Methods Subjects undergoing thoracic or upper abdominal surgery with planned thoracic epidural placement at T10 or higher were enrolled in this randomized double-blind study. Subjects were allocated into 1 of 2 groups for preoperative epidural placement: ultrasound guidance (group US) or palpation (group Palp). Subjects randomized to group US had a preprocedural ultrasound examination to identify pertinent spinal anatomy and make appropriate marks on the skin identifying midline and interlaminar spaces for targeted Tuohy needle insertion. Subjects in group Palp had a skin marking performed by palpation alone. Using the skin markings, all epidurals were performed using a loss of resistance to saline technique. Block levels were assessed with ice and pain scores obtained by a blinded nurse in the postanesthesia care unit. The primary outcome was procedural time from needle insertion to loss of resistance in the epidural space. Results Seventy subjects were recruited and completed the study protocol. The median time for epidural needle placement to achieve loss of resistance in group US and group Palp was 188.5 seconds (interquartile range [IQR], 79.0–515.0) and 242.0 seconds (IQR, 87.0–627.0), respectively (P = 0.188). Using ultrasound to mark the skin overlying the targeted epidural space took a median time of 85 seconds (IQR, 69–113) for group US and 35 seconds (IQR, 27–51) for group Palp (P < 0.001). The number of needle passes was not significantly different between the 2 groups (P = 0.31). The use of ultrasound assistance resulted in a decreased number of needle skin punctures to achieve loss of resistance (P = 0.005). Mean pain scores after surgery were lower in group US compared to group Palp: 3.0 versus 4.7, respectively (P = 0.015). Conclusions This is the first randomized study to evaluate the efficacy of preprocedural ultrasound marking for placement of thoracic epidural catheters. We observed that preprocedural ultrasound did not significantly reduce the time required to identify the thoracic epidural space via loss of resistance. Clinical Trials Registration: NCT02785055 (https://clinicaltrials.gov/).

Adductor Canal Block for Total Knee Arthroplasty: A Review of the Current Evidence

The positive impact of regional anesthesia on surgical outcome has continued to evolve. In recent years, the focus of acute pain management strategies following total knee arthroplasty has shifted from femoral nerve block to adductor canal block. We systematically analyzed the safety and efficacy of adductor canal blocks by reviewing 78 peer-reviewed publications, including 13 randomized controlled trials. There are a number of studies supporting the adductor canal nerve block as a viable alternative for postoperative analgesia after total knee arthroplasty. This novel block has been consistently demonstrated to have equivalent analgesic efficacy compared to femoral nerve block, while simultaneously reducing quadriceps weakness significantly less than femoral nerve block, thus facilitating earlier active mobilization. With focus on early rehabilitation, adductor canal block may be considered a contributory factor preventing complications such as deep vein thrombosis and joint rigidity from the lack of early mobilization. These advances could potentially result in a reduction of total length of hospital stay and therefore a reduction in associated health care costs. Based on the current evidence, we recommend that an adductor canal block could replace a femoral nerve block as the primary regional analgesic following total knee arthroplasty. *Corresponding author: Stanley C. Yuan, Department of Anesthesiology, Virginia Mason Medical Center 1100 9th Avenue, Seattle, Washington, 98101, USA United States,Tel: (206) 223-6980; E-mail: Stanley.yuan@virginiamason.org

Virtual Cadaver Laboratory—Anatomy Pearls in Regional Anesthesia to Improve Clinical Success

Learning Objectives: As a result of completing this activity, the participant will be able to Compare highlighted anatomic structures in photographs of fresh tissue dissections with anatomic structures on ultrasound images Summarize the anatomic relationships of nerves to surrounding structures that facilitate placement of nerve blocks and improve clinical efficacy of regional anesthesia Examine, at a gross anatomy level, why some nerve blocks are more appropriate than others for specific surgeries of the upper and lower extremity Recognize anatomic variations in ultrasound images and cadaver dissections and correlate how these variations affect regional anesthesia

Comparison of Continuous Proximal Versus Distal Adductor Canal Blocks for Total Knee Arthroplasty: A Randomized, Double-Blind, Noninferiority Trial

Background and Objectives Adductor canal blocks (ACBs) are associated with improved analgesia, preserved quadriceps strength, and decreased length of hospitalization after total knee arthroplasty (TKA). However, controversy remains regarding the ideal location of a continuous block within the adductor canal, and it remains unclear whether similar clinical benefits are obtained irrespective of block location. In this randomized, double-blind, noninferiority study, we hypothesized that a continuous proximal ACB provides postoperative analgesia that is no worse than a continuous distal ACB. Methods Subjects presenting for unilateral TKA were randomized in a 1:1 ratio to either a continuous proximal or distal ACB group. The primary outcome of this noninferiority study was opioid consumption within the first 24 hours following surgery. Secondary outcomes included quadriceps strength, pain scores, distance ambulated, and patient satisfaction. Results Seventy-three subjects, 36 from the proximal group and 37 from the distal group, completed the study per protocol. The intention-to-treat analysis demonstrated a cumulative mean intravenous morphine equivalent consumption difference between the proximal and distal groups of −7.2 mg (95% confidence interval, −14.8 to 0.4; P < 0.001), demonstrating noninferiority of the proximal approach. The per-protocol analysis yielded similar results: −6.2 mg (95% confidence interval, −14.1 to 1.6; P < 0.001). No secondary outcomes showed statistically significant differences between the proximal and distal groups. Conclusions This study demonstrates that a continuous proximal ACB offers noninferior postoperative analgesia compared with a distal continuous ACB in the first 24 hours after TKA. Clinical Trial Registration ClinicalTrials.gov (NCT02701114).

Comparison of Anterior Suprascapular, Supraclavicular, and Interscalene Nerve Block Approaches for Major Outpatient Arthroscopic Shoulder SurgeryA Randomized, Double-blind, Noninferiority Trial

Background: The interscalene nerve block provides analgesia for shoulder surgery, but is associated with diaphragm paralysis. One solution may be performing brachial plexus blocks more distally. This noninferiority study evaluated analgesia for blocks at the supraclavicular and anterior suprascapular levels, comparing them individually to the interscalene approach. Methods: One hundred-eighty-nine subjects undergoing arthroscopic shoulder surgery were recruited to this double-blind trial and randomized to interscalene, supraclavicular, or anterior suprascapular block using 15 ml, 0.5% ropivacaine. The primary outcome was numeric rating scale pain scores analyzed using noninferiority testing. The predefined noninferiority margin was one point on the 11-point pain scale. Secondary outcomes included opioid consumption and pulmonary assessments. Results: All subjects completed the study through the primary outcome analysis. Mean pain after surgery was: interscalene = 1.9 (95% CI, 1.3 to 2.5), supraclavicular = 2.3 (1.7 to 2.9), suprascapular = 2.0 (1.4 to 2.6). The primary outcome, mean pain score difference of supraclavicular–interscalene was 0.4 (–0.4 to 1.2; P = 0.088 for noninferiority) and of suprascapular–interscalene was 0.1 (–0.7 to 0.9; P = 0.012 for noninferiority). Secondary outcomes showed similar opioid consumption with better preservation of vital capacity in the anterior suprascapular group (90% baseline [P < 0.001]) and the supraclavicular group (76% [P = 0.002]) when compared to the interscalene group (67%). Conclusions: The anterior suprascapular block, but not the supraclavicular, provides noninferior analgesia compared to the interscalene approach for major arthroscopic shoulder surgery. Pulmonary function is best preserved with the anterior suprascapular nerve block.

Reply to Dr Costache et al

To the Editor: We would like to congratulate Auyong et al for their study examining the clinical benefits of ultrasound assistance in thoracic epidural placement and believe this to be an important area for further investigation. We also use ultrasound for thoracic epidural insertion and would like to comment to assist readers in replicating the technique. The authors refer to “targeted Tuohy insertions” based on the ultrasound images but did not comment on their choice of initial insertion point or of the angulation of the needle. We use a needle insertion site 1 cm lateral and 1 cm caudad from the intersection point of the midline and interlaminar space marks. The needle is then angulated slightly medial and cephalad, so that the tip will reach the intersection point of the midline and interlaminar space at the depth to the lamina as noted on the preprocedural images. It should be noted that the needle depth at this trajectory will inevitably exceed the measured vertical skin-lamina depth on ultrasound. We would be interested to know if the intention of the initial needle pass in this study was to enter the epidural space or to first contact the lamina prior to needle redirection. The latter would provide some reassurance that the needle has not been advanced too deep in the first instance, but would increase the number of documented needle passes. The authors did not report how much time elapsed before marking of the back and the start of the actual procedure. We have found that minor changes in patient position, which can occur with the onset of sedation, may significantly alter the relationship between skin markings and the underlying anatomical structures of interest. This should be borne in mind if difficulty in locating the epidural space is encountered, and consideration given to a repeat scan using a sterile probe cover. We agree with Auyong et al that the value of ultrasound may not be apparent in the routine patient, but lies instead in facilitating epidural insertion in patients with challenging anatomy, including patients with scoliosis, elderly patients in whom it is difficult to discern spinous processes