Neil A. Hanson

Continuous ultrasound-guided adductor canal block for total knee arthroplasty: a randomized, double-blind trial.

BACKGROUND:Adductor canal blocks have shown promise in reducing postoperative pain in total knee arthroplasty patients. No randomized, controlled studies, however, evaluate the opioid-sparing benefits of a continuous 0.2% ropivacaine infusion at the adductor canal. We hypothesized that a continuous adductor canal block would decrease postoperative opioid consumption. METHODS:Eighty subjects presenting for primary unilateral total knee arthroplasty were randomized to receive either a continuous ultrasound-guided adductor canal block with 0.2% ropivacaine or a sham catheter. All subjects received a preoperative single-injection femoral nerve block with spinal anesthesia as is standard of care at our institution. Cumulative IV morphine consumption 48 hours after surgery was evaluated with analysis of covariance, adjusted for baseline characteristics. Secondary outcomes included resting pain scores (numeric rating scale), peak pain scores during physical therapy on postoperative days 1 and 2, quadriceps maximum voluntary isometric contraction, distance ambulated during physical therapy, postoperative nausea and vomiting, and satisfaction with analgesia. RESULTS:Eighty subjects were randomized, and 76 completed the study per-protocol. The least-square mean difference in cumulative morphine consumption over 48 hours (block − sham) was −16.68 mg (95% confidence interval, −29.78 to −3.59, P = 0.013). Total morphine use between 24 and 48 hours (after predicted femoral nerve block resolution) also differed by least-square mean −11.17 mg (95% confidence interval,: −19.93 to −2.42, P = 0.013). Intention-to-treat analysis was similar to the per-protocol results. Functional outcomes revealed subjects in the adductor canal catheter group had better quadriceps strength (P = 0.010) and further distance ambulated (P = 0.034) on postoperative day 2. CONCLUSIONS:A continuous adductor canal block for total knee arthroplasty reduces opioid consumption compared with that of placebo in the first 48 hours after surgery. Other outcomes including quadriceps strength, distance ambulated, and pain scores all show benefit from an adductor canal catheter after total knee arthroplasty but require further study before being interpreted as conclusive.

Reduced Length of Hospitalization in Primary Total Knee Arthroplasty Patients Using an Updated Enhanced Recovery After Orthopedic Surgery (ERAS) Pathway

Decreasing hospital length of stay may attenuate costs associated with total knee arthroplasty. The purpose of this study was to determine if updates to an existing orthopedic enhanced recovery after surgery (ERAS) pathway would improve length of hospitalization. Clinical and demographic data were collected on 252 primary total knee arthroplasties between January 2012 and July 2013. Pre-updated and post-updated ERAS pathway cohorts were analyzed for length of stay, clinical outcomes, and re-admissions. The mean length of stay decreased from 76.6 hours to 56.1 hours after implementation of the evidence-based orthopedic enhanced recovery after surgery pathway (P<0.001). This improvement was possible without a concomitant increase in readmission rates.

Delayed quadriceps weakness after continuous adductor canal block for total knee arthroplasty: a case report

Adductor canal catheters have been shown to improve analgesia while maintaining quadriceps strength after total knee arthroplasty. We describe a patient who underwent total knee arthroplasty that likely had delayed quadriceps weakness as a result of a standard continuous 0.2% ropivacaine infusion at 8 ml/h within the adductor canal. On the day of surgery, the patient was able to stand and ambulate with minimal assistance. On the first post‐operative day after surgery, approximately 20 h after starting the ropivacaine infusion, profound weakness of the quadriceps was noted with no ability to stand. Contrast subsequently injected through the adductor canal catheter under fluoroscopy revealed proximal spread approaching the common femoral nerve with as little as 2 ml of volume. This rare case of profound quadriceps weakness after a continuous adductor canal block reveals that local anaesthetic at the adductor canal can spread in a retrograde fashion towards the common femoral nerve, potentially resulting in quadriceps weakness.

Systematic ultrasound identification of the dorsal scapular and long thoracic nerves during interscalene block.

Background and Objectives The use of ultrasound for in-plane interscalene block shifts needle insertion to a more posterior approach through the middle scalene muscle, when compared with classic nerve stimulator techniques. Branches from the brachial plexus, including the dorsal scapular and long thoracic nerves, are often anatomically located within the middle scalene muscle. The aim of this study was to use ultrasound to identify and characterize the frequency and position of the dorsal scapular and long thoracic nerves located in the middle scalene muscle. Methods We recruited 50 subjects who presented for shoulder surgery. Before block placement, ultrasound was used to evaluate the area posterior to the brachial plexus for visible segments of the long thoracic and dorsal scapular nerves. If nerves were identified, a stimulating Tuohy needle was advanced in close proximity. Current was then applied through the needle, and motor response confirmed the visualized nerve as being either the dorsal scapular nerve or long thoracic nerve. Results Ninety percent of the subjects had a nerve visible under ultrasound assessment within or superficial to the middle scalene muscle. The nerves were located at similar depth as the perceived C6 nerve root, at 1.1 ± 0.4 cm from skin and 0.7 ± 0.4 cm posterior from the brachial plexus. Stimulation revealed that the nerve identified on ultrasound was the dorsal scapular nerve (77%) or the long thoracic nerve (23%). Conclusions This descriptive study revealed that the dorsal scapular and long thoracic nerves routinely could be identified with ultrasound.

Evidence-Based Medicine for Ultrasound-Guided Regional Anesthesia

Available evidence favoring the use of ultrasound for regional anesthesia is reviewed, updated, and critically assessed. Important outcome advantages include decreased time to block onset; decreased risk of local anesthetic systemic toxicity; and, depending on the outcome definition, increased block success rates. Ultrasound guidance, peripheral nerve blocks, and central neuraxial blocks are discussed.

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.

The Effect of Fixation Technique on Continuous Interscalene Nerve Block Catheter Success: A Randomized, Double-blind Trial

BACKGROUND: Continuous peripheral nerve blocks offer advantages over single-injection blocks, including extended analgesia and reduction in opioid consumption. These benefits require that the perineural catheter remain intact for the duration of the planned local anesthetic infusion. Mechanical displacement of catheters, leaking, and consequent failure are known complications. The aim of this study was to evaluate continuous perineural catheter tip-to-nerve apposition in vivo over 48 hours comparing 2 different simple fixation strategies. METHODS: Subjects presenting for a continuous interscalene nerve block were randomized to perineural catheter fixation with 1 of 2 types of adhesive: Dermabond (2-octylcyanoacrylate) or Mastisol (alcohol 23A, gum mastic, storax, and methyl salicylate), covered with a simple transparent dressing. The primary outcome was the evaluation of catheter-to-nerve apposition maintenance over 48 hours via both a blinded ultrasound evaluation of local anesthetic distribution and a blinded clinical assessment. Secondary outcomes included leakage at the catheter site, pain scores, opioid consumption, catheter-to-skin migration at the insertion site, and patient satisfaction. RESULTS: Sixty-six subjects were recruited and randomized to compare adhesive group catheter tip-to-nerve apposition on postoperative day 2 (POD 2). Within the intention-to-treat cohort, a statistically significant decrease of perineural catheter tip-to-nerve apposition in the Mastisol group (64.7%) compared with the Dermabond group (90.6%) on POD 2 (odds ratios [OR] 0.19; 95% confidence interval [CI] 0.05–0.75; P = .012) was observed. Similar results were observed on POD 1 (OR 0.19; 95% CI 0.03–1.38; P = NS) and POD 2 (OR 0.14; 95% CI 0.02–0.97; P = .008) within the as-treated cohort. Catheter leakage (OR 67; 95% CI 7.3–589) and median catheter migration difference at the skin insertion site (2.0 cm; 95% CI 0.5–2.5) were also significantly greater in the Mastisol group than in the Dermabond group from POD 0 to POD 2 (P < .001). Median postoperative opioid consumption difference in morphine equivalents (3.2 mg; 95% CI – 9.0 to 14.2) was not significantly different between the Dermabond and the Mastisol groups through POD 2 (P = .542). CONCLUSIONS: Perineural catheter fixation with Dermabond in continuous interscalene nerve block improves maintenance of catheter-to-nerve apposition when compared with Mastisol.