A Multidisciplinary Patient-Specific Opioid Prescribing and Tapering Protocol Is Associated with a Decrease in Total Opioid Dose Prescribed for Six Weeks After Total Hip Arthroplasty.

OBJECTIVE: This retrospective cohort study tested the hypothesis that implementing a multidisciplinary patient-specific discharge protocol for prescribing and tapering opioids after total hip arthroplasty (THA) will decrease the morphine milligram equivalent (MME) dose of opioids prescribed. METHODS: With institutional review board approval, we analyzed a Perioperative Surgical Home database and prescription data for all primary THA patients three months before (PRE) and three months after (POST) implementation of this new discharge opioid protocol based on patients' prior 24-hour inpatient opioid consumption. The primary outcome was total opioid dosage in MME prescribed and opioid refills for six weeks after surgery. Secondary outcomes included the number of tablets and MME prescribed at discharge, in-hospital opioid consumption, length of stay, and postoperative complications. RESULTS: Forty-nine cases (25 PRE and 24 POST) were included. Total median (10th-90th percentiles) MME for six weeks postoperatively was 900 (57-2082) MME PRE vs 295 (69-741) MME POST (mean difference = 721, 95% confidence interval [CI] = 127-1316, P = 0.007, Mann-Whitney U test). Refill rates did not differ. The median (10th-90th percentiles) initial discharge prescription in MME was 675 (57-1035) PRE vs 180 (18-534) POST (mean difference = 387, 95% CI = 156-618, P = 0.003, Mann-Whitney U test) MME. There were no differences in other outcomes. CONCLUSIONS: Implementation of a patient-specific prescribing and tapering protocol decreases the mean six-week dosage of opioid prescribed by 63% after THA without increasing the refill rate.

Outcomes of Ambulatory Upper Extremity Surgery Patients Discharged Home with Perineural Catheters from a Veterans Health Administration Medical Center.

OBJECTIVE: The feasibility and safety of managing ambulatory continuous peripheral nerve blocks (CPNB) in Veterans Health Administration (VHA) patients are currently unknown. We aimed to characterize the outcomes of a large VHA cohort of ambulatory upper extremity surgery patients discharged with CPNB and identify differences, if any, between catheter types. METHODS: With institutional review board approval, we reviewed data for consecutive patients from a single VHA hospital who had received ambulatory CPNB for upper extremity surgery from March 2011 to May 2017. The composite primary outcome was the occurrence of any catheter-related issue or additional all-cause health care intervention after discharge. Our secondary outcome was the ability to achieve regular daily telephone contact. RESULTS: Five hundred one patients formed the final sample. The incidence of any issue or health care intervention was 104/274 (38%) for infraclavicular, 58/185 (31%) for interscalene, and 14/42 (33%) for supraclavicular; these rates did not differ between groups. Higher ASA status was associated with greater odds of having any issue, whereas increasing age was slightly protective. Distance was associated with an increase in catheter-related issues (P < 0.01) but not additional health care interventions (P = 0.51). Only interscalene catheter patients (3%) reported breathing difficulty. Infraclavicular catheter patients had the most emergency room visits but rarely for CPNB issues. Consistent daily telephone contact was not achieved. CONCLUSIONS: For VHA ambulatory CPNB patients, the combined incidence of a catheter-related issue or additional health care intervention was approximately one in three patients and did not differ by brachial plexus catheter type. Serious adverse events were generally uncommon.

Are Case Volume and Facility Complexity Level Associated With Postoperative Complications After Hip Fracture Surgery in the Veterans Affairs Healthcare System?

BACKGROUND: Hospital-related factors associated with mortality and morbidity after hip fracture surgery are not completely understood. The Veterans Health Administration (VHA) is the largest single-payer, networked healthcare system in the country serving a relatively homogenous patient population with facilities that vary in size and resource availability. These characteristics provide some degree of financial and patient-level controls to explore the association, if any, between surgical volume and facility resource availability and hospital performance regarding postoperative complications after hip fracture surgery. QUESTIONS/PURPOSES: (1) Do VHA facilities with the highest complexity level designation (Level 1a) have a disproportionate number of better-than-expected performance outliers for major postoperative complications compared with lower-complexity level facilities? (2) Do VHA facilities with higher hip fracture surgical volume have a disproportionate number of better-than-expected performance outliers for major postoperative complications compared with lower-volume facilities? METHODS: We explored the Veterans Affairs Surgical Quality Improvement Project (VASQIP) database from October 2001 to September 2012 for records of hip fracture surgery performed. Data reliability of the VASQIP database has been previously validated. We excluded nine of the 98 VHA facilities for contributing fewer than 30 records. The remaining 89 VHA facilities provided 23,029 records. The VHA designates a complexity level to each facility based on multiple criteria. We labeled facilities with a complexity Level 1a (38 facilities)-the highest achievable VHA designated complexity level-as high complexity; we labeled all other complexity level designations as low complexity (51 facilities). Facility volume was divided into tertiles: high (> 277 hip fracture procedures during the sampling frame), medium (204 to 277 procedures), and low (< 204 procedures). The patient population treated by low-complexity facilities was older, had a higher prevalence of severe chronic obstructive pulmonary disease (26% versus 22%, p < 0.001), and had a higher percentage of patients having surgery within 2 days of hospital admission (83% versus 76%, p < 0.001). High-complexity facilities treated more patients with recent congestive heart failure exacerbation (4% versus 3%, p < 0.001). We defined major postoperative complications as having at least one of the following: death within 30 days of surgery, cardiac arrest requiring cardiopulmonary resuscitation, new q-wave myocardial infarction, deep vein thrombosis and/or pulmonary embolism, ventilator dependence for at least 48 hours after surgery, reintubation for respiratory or cardiac failure, acute renal failure requiring renal replacement therapy, progressive renal insufficiency with a rise in serum creatinine of at least 2 mg/dL from preoperative value, pneumonia, or surgical site infection. We used the observed-to-expected ratio (O/E ratio)-a risk-adjusted metric to classify facility performance-for major postoperative complications to assess the performance of VHA facilities. Outlier facilities with 95% confidence intervals (95% CI) for O/E ratio completely less than 1.0 were labeled "exceed expectation;" those that were completely greater than 1.0 were labeled "below expectation." We compared differences in the distribution of outlier facilities between high and low-complexity facilities, and between high-, medium-, and low-volume facilities using Fisher's exact test. RESULTS: We observed no association between facility complexity level and the distribution of outlier facilities (high-complexity: 5% exceeded expectation, 5% below expectation; low-complexity: 8% exceeded expectation, 2% below expectation; p = 0.742). Compared with high-complexity facilities, the adjusted odds ratio for major postoperative complications for low-complexity facilities was 0.85 (95% CI, 0.67-1.09; p = 0.108).We observed no association between facility volume and the distribution of outlier facilities: 3% exceeded expectation and 3% below expectation for high-volume; 10% exceeded expectation and 3% below expectation for medium-volume; and 7% exceeded expectation and 3% below expectation for low-volume; p = 0.890). The adjusted odds ratios for major postoperative complications were 0.87 (95% CI, 0.73-1.05) for low- versus high-volume facilities and 0.89 (95% CI, 0.79-1.02] for medium- versus high-volume facilities (p = 0.155). CONCLUSIONS: These results do not support restricting facilities from treating hip fracture patients based on historical surgical volume or facility resource availability. Identification of consistent performance outliers may help health care organizations with multiple facilities determine allocation of services and identify characteristics and processes that determine outlier status in the interest of continued quality improvement. LEVEL OF EVIDENCE: Level III, therapeutic study.

Care of the Patient With a Peripheral Nerve Block.

Long-acting peripheral nerve blocks provide effective postoperative pain management, but there are risks associated with rendering an extremity insensate. Perianesthesia nurses play a major role in anticipating and mitigating risks and carefully monitoring patients for potential complications. This article presents uncommon but important considerations related to the care of patients with a peripheral nerve block. These include compartment syndrome, local anesthetic systemic toxicity, thermal injuries, falls, and fractures as well as their management and prevention. The nurse's responsibility in discharge education after a peripheral nerve block is also discussed.

Preliminary Experience Using Eye-Tracking Technology to Differentiate Novice and Expert Image Interpretation for Ultrasound-Guided Regional Anesthesia.

OBJECTIVES: Objective measures are needed to guide the novice's pathway to expertise. Within and outside medicine, eye tracking has been used for both training and assessment. We designed this study to test the hypothesis that eye tracking may differentiate novices from experts in static image interpretation for ultrasound (US)-guided regional anesthesia. METHODS: We recruited novice anesthesiology residents and regional anesthesiology experts. Participants wore eye-tracking glasses, were shown 5 sonograms of US-guided regional anesthesia, and were asked a series of anatomy-based questions related to each image while their eye movements were recorded. The answer to each question was a location on the sonogram, defined as the area of interest (AOI). The primary outcome was the total gaze time in the AOI (seconds). Secondary outcomes were the total gaze time outside the AOI (seconds), total time to answer (seconds), and time to first fixation on the AOI (seconds). RESULTS: Five novices and 5 experts completed the study. Although the gaze time (mean ± SD) in the AOI was not different between groups (7 ± 4 seconds for novices and 7 ± 3 seconds for experts; P = .150), the gaze time outside the AOI was greater for novices (75 ± 18 versus 44 ± 4 seconds for experts; P = .005). The total time to answer and total time to first fixation in the AOI were both shorter for experts. CONCLUSIONS: Experts in US-guided regional anesthesia take less time to identify sonoanatomy and spend less unfocused time away from a target compared to novices. Eye tracking is a potentially useful tool to differentiate novices from experts in the domain of US image interpretation.

Availability and Readability of Online Patient Education Materials Regarding Regional Anesthesia Techniques for Perioperative Pain Management.

OBJECTIVE: Patient education materials (PEM) should be written at a sixth-grade reading level or lower. We evaluated the availability and readability of online PEM related to regional anesthesia and compared the readability and content of online PEM produced by fellowship and nonfellowship institutions. METHODS: With IRB exemption, we constructed a cohort of online regional anesthesia PEM by searching Websites from North American academic medical centers supporting a regional anesthesiology and acute pain medicine fellowships and used a standardized Internet search engine protocol to identify additional nonfellowship Websites with regional anesthesia PEM based on relevant keywords. Readability metrics were calculated from PEM using the TextStat 0.1.4 textual analysis package for Python 2.7 and compared between institutions with and without a fellowship program. The presence of specific descriptive PEM elements related to regional anesthesia was also compared between groups. RESULTS: PEM from 17 fellowship and 15 nonfellowship institutions were included in analyses. The mean (SD) Flesch-Kincaid Grade Level for PEM from the fellowship group was 13.8 (2.9) vs 10.8 (2.0) for the nonfellowship group (p = 0.002). We observed no other differences in readability metrics between fellowship and nonfellowship institutions. Fellowship-based PEM less commonly included descriptions of the following risks: local anesthetic systemic toxicity (p = 0.033) and injury due to an insensate extremity (p = 0.003). CONCLUSIONS: Available online PEM related to regional anesthesia are well above the recommended reading level. Further, fellowship-based PEM posted are at a higher reading level than PEM posted by nonfellowship institutions and are more likely to omit certain risk descriptions.

Comparative Echogenicity of an Epidural Catheter and 2 New Catheters Designed for Ultrasound-Guided Continuous Peripheral Nerve Blocks.

Visualization of the catheter during ultrasound-guided continuous nerve block performance may be difficult but is an essential skill for regional anesthesiologists. The objective of this in vitro study was to evaluate 2 newer catheters designed for enhanced echogenicity and compare them to a widely used catheter not purposely designed for ultrasound guidance. Outcomes were the numbers of first-place rankings among all 3 catheters and scores on individual echogenicity criteria as assessed by 2 blinded reviewers. Catheters designed for echogenicity are not superior to an older regional anesthesia catheter, and results suggest that catheter preference for ultrasound-guided placement may be subjective.

A matched case-control comparison of hospital costs and outcomes for knee replacement patients admitted postoperatively to acute care versus rehabilitation.

For select total knee arthroplasty (TKA) patients, we have established an alternative pathway to bypass the acute care surgical ward and directly admit patients from the post-anesthesia care unit to on-campus rehabilitation. We retrospectively examined whether this 'fast track' pathway decreased costs and improved patient outcomes. After reviewing records of consecutive primary unilateral TKA patients over a 15-month period, each patient admitted to rehabilitation was matched with a control admitted to the acute care ward. The primary outcome was estimated total hospitalization cost (length of stay in days multiplied by the average cost per day). Secondary outcomes were length of stay, in-hospital pain scores, opioid use, maximum ambulatory distance and 30-day readmission, morbidity, and mortality. Of the 262 TKA patients during the study period, 14 were admitted to rehabilitation and were matched to 14 patients admitted to acute care. Estimated total hospitalization cost [median (10th-90th percentiles)] was US$30,755 (US$23,066-38,444) for ward patients compared to US$17,620 (US$13,215-33,918) for rehabilitation patients (P = 0.006). This difference [mean (95% CI)] was US$10,143 (US$2174-18,112). There were no other differences. For facilities similar to ours, direct postoperative admission of select TKA patients to subacute rehabilitation may be less costly than acute care and may not negatively affect outcomes.

Comparative Effectiveness of Two Ultrasound-Guided Regional Block Techniques for Surgical Anesthesia in Open Unilateral Inguinal Hernia Repair.

Transversus abdominis plane (TAP) and ilioinguinal/iliohypogastric (II/IH) nerve blocks have been described as analgesic adjuncts for inguinal hernia repair, but the efficacy of these techniques in providing intraoperative anesthesia, either individually or together, is not known. We designed this retrospective cohort study to test the hypothesis that combining TAP and II/IH nerve blocks ("double TAP" technique) results in greater accordance between the preoperative anesthetic plan and actual anesthetic technique provided when compared to TAP alone. Based on this study, double TAP may be preferred for patients undergoing open inguinal hernia repair who wish to avoid general anesthesia.

Feasibility of eye-tracking technology to quantify expertise in ultrasound-guided regional anesthesia.

Ultrasound-guided regional anesthesia (UGRA) requires an advanced procedural skill set that incorporates both sonographic knowledge of relevant anatomy as well as technical proficiency in needle manipulation in order to achieve a successful outcome. Understanding how to differentiate a novice from an expert in UGRA using a quantifiable tool may be useful for comparing educational interventions that could improve the rate at which one develops expertise. Exploring the gaze pattern of individuals performing a task has been used to evaluate expertise in many different disciplines, including medicine. However, the use of eye-tracking technology has not been previously applied to UGRA. The purpose of this preliminary study is to establish the feasibility of applying such technology as a measurement tool for comparing procedural expertise in UGRA. eye-tracking data were collected from one expert and one novice utilizing Tobii Glasses 2 while performing a simulated ultrasound-guided thoracic paravertebral block in a gel phantom model. Area of interest fixations were recorded and heat maps of gaze fixations were created. Results suggest a potential application of eye-tracking technology in the assessment of UGRA learning and performance.

Evaluation of a Standardized Program for Training Practicing Anesthesiologists in Ultrasound-Guided Regional Anesthesia Skills.

OBJECTIVES: Practicing anesthesiologists have generally not received formal training in ultrasound-guided perineural catheter insertion. We designed this study to determine the efficacy of a standardized teaching program in this population. METHODS: Anesthesiologists in practice for 10 years or more were recruited and enrolled to participate in a 1-day program: lectures and live-model ultrasound scanning (morning) and faculty-led iterative practice and mannequin-based simulation (afternoon). Participants were assessed and recorded while performing ultrasound-guided perineural catheter insertion at baseline, at midday (interval), and after the program (final). Videos were scored by 2 blinded reviewers using a composite tool and global rating scale. Participants were surveyed every 3 months for 1 year to report the number of procedures, efficacy of teaching methods, and implementation obstacles. RESULTS: Thirty-two participants were enrolled and completed the program; 31 of 32 (97%) completed the 1-year follow-up. Final scores [median (10th-90th percentiles)] were 21.5 (14.5-28.0) of 30 points compared to 14.0 (9.0-20.0) at interval (P < .001 versus final) and 12.0 (8.5-17.5) at baseline (P < .001 versus final), with no difference between interval and baseline. The global rating scale showed an identical pattern. Twelve of 26 participants without previous experience performed at least 1 perineural catheter insertion after training (P < .001). However, there were no differences in the monthly average number of procedures or complications after the course when compared to baseline. CONCLUSIONS: Practicing anesthesiologists without previous training in ultrasound-guided regional anesthesia can acquire perineural catheter insertion skills after a 1-day standardized course, but changing clinical practice remains a challenge.

Comparative effectiveness of infraclavicular and supraclavicular perineural catheters for ultrasound-guided through-the-catheter bolus anesthesia.

OBJECTIVES: Using a through-the-needle local anesthetic bolus technique, ultrasound-guided infraclavicular perineural catheters have been shown to provide greater analgesia compared to supraclavicular catheters. A through-the-catheter bolus technique, which arguably "tests" the anesthetic efficacy of the catheter before initiating an infusion, has been validated for infraclavicular catheters but not supraclavicular catheters. This study investigated the through-the-catheter bolus technique for supraclavicular catheters and tested the hypothesis that infraclavicular catheters provide faster onset of brachial plexus anesthesia. METHODS: Preoperatively, patients were randomly assigned to receive either a supraclavicular or an infraclavicular catheter using an ultrasound-guided nonstimulating catheter insertion technique with a mepivacaine bolus via the catheter and ropivacaine perineural infusion initiated postoperatively. The primary outcome was time to achieve complete sensory anesthesia in the ulnar and median nerve distributions. Secondary outcomes included procedural time, procedure-related pain and complications, and postoperative pain, opioid consumption, sleep disturbances, and motor weakness. RESULTS: Fifty patients were enrolled in the study; all but 2 perineural catheters were successfully placed per protocol. Twenty-one of 24 (88%) and 24 of 24 (100%) patients in the supraclavicular and infraclavicular groups, respectively, achieved complete sensory anesthesia by 30 minutes (P= .088). There was no difference in the time to achieve complete sensory anesthesia. Supraclavicular patients reported more sleep disturbances postoperatively, but there were no statistically significant differences in other outcomes. CONCLUSIONS: Both supraclavicular and infraclavicular perineural catheters using a through-the-catheter bolus technique provide effective brachial plexus anesthesia.

Comparison of catheter tip migration using flexible and stimulating catheters inserted into the adductor canal in a cadaver model.

Use of adductor canal blocks and catheters for perioperative pain management following total knee arthroplasty is becoming increasingly common. However, the optimal equipment, timing of catheter insertion, and catheter dislodgement rate remain unknown. A previous study has suggested, but not proven, that non-tunneled stimulating catheters may be at increased risk for catheter migration and dislodgement after knee manipulation. We designed this follow-up study to directly compare tip migration of two catheter types after knee range of motion exercises. In a male unembalmed human cadaver, 30 catheter insertion trials were randomly assigned to one of two catheter types: flexible or stimulating. All catheters were inserted using an ultrasound-guided short-axis in-plane technique. Intraoperative knee manipulation similar to that performed during surgery was simulated by five sequential range of motion exercises. A blinded regional anesthesiologist performed caliper measurements on the ultrasound images before and after exercise. Changes in catheter tip to nerve distance (p = 0.547) and catheter length within the adductor canal (p = 0.498) were not different between groups. Therefore, catheter type may not affect the risk of catheter tip migration when placed prior to knee arthroplasty.

A retrospective comparative provider workload analysis for femoral nerve and adductor canal catheters following knee arthroplasty.

Adductor canal catheters preserve quadriceps strength better than femoral nerve catheters and may facilitate postoperative ambulation following total knee arthroplasty. However, the effect of this newer technique on provider workload, if any, is unknown. We conducted a retrospective provider workload analysis comparing these two catheter techniques; all other aspects of the clinical pathway remained the same. The primary outcome was number of interventions recorded per patient postoperatively. Secondary outcomes included infusion duration, ambulation distance, opioid consumption, and hospital length of stay. Adductor canal patients required a median (10-90th percentiles) of 0.0 (0.0-2.6) interventions compared to 1.0 (0.3-3.0) interventions for femoral patients (p < 0.001); 18/23 adductor canal patients (78 %) compared to 2/22 femoral patients (9 %) required no interventions (p < 0.001). Adductor canal catheter infusions lasted 2.0 (1.4-2.0) days compared to 1.5 (1.0-2.7) days in the femoral group (p = 0.016). Adductor canal patients ambulated further [mean (SD)] than femoral patients on postoperative day 1 [24.5 (21.7) vs. 11.9 (14.6) meters, respectively; p = 0.030] and day 2 [44.9 (26.3) vs. 22.0 (22.2) meters, respectively; p = 0.003]. Postoperative opioid consumption and length of stay were similar between groups. We conclude that adductor canal catheters offer both patient and provider benefits when compared to femoral nerve catheters.

Application of echogenic technology for catheters used in ultrasound-guided continuous peripheral nerve blocks.

Limited data exist regarding the echogenicity of perineural catheters, but visualization is crucial to ensure accurate placement and efficacy of the subsequent local anesthetic infusion. The objective of this study was to determine the comparative echogenicity of various regional anesthesia catheters. In an in vitro porcine-bovine model, we compared the echogenic qualities of 3 commercially available regional anesthesia catheters and 1 catheter under development to optimize echogenicity. Outcomes included visual echogenicity ranking, image quality, and scanning time, as assessed by 2 blinded investigators. The experimental catheter was found to be more echogenic than 2 of the 3 comparators.

A pilot in vitro evaluation of the "air test" for perineural catheter tip localization by a novice regional anesthesiologist.

The "air test" is used clinically to infer perineural catheter location and has been recently evaluated for use by experts. However, its utility for practitioners with less experience is unknown. We tested the hypothesis that the air test, when performed by a novice regional anesthesiologist, will improve assessment of perineural catheter tip position in a validated porcine-bovine model and determined the test's positive and negative predictive values, sensitivity, and specificity for a novice. In contrast to the results of the expert study, the air test did not improve the novice's assessment of perineural catheter tip location over chance.

A randomized comparison of proximal and distal ultrasound-guided adductor canal catheter insertion sites for knee arthroplasty.

OBJECTIVES: Proximal and distal (mid-thigh) ultrasound-guided continuous adductor canal block techniques have been described but not yet compared, and infusion benefits or side effects may be determined by catheter location. We hypothesized that proximal placement will result in faster onset of saphenous nerve anesthesia, without additional motor block, compared to a distal technique. METHODS: Preoperatively, patients receiving an ultrasound-guided nonstimulating adductor canal catheter for knee arthroplasty were randomly assigned to either proximal or distal insertion. A local anesthetic bolus was administered via the catheter after successful placement. The primary outcome was the time to achieve complete sensory anesthesia in the saphenous nerve distribution. Secondary outcomes included procedural time, procedure-related pain and complications, postoperative pain, opioid consumption, and motor weakness. RESULTS: Proximal insertion (n = 23) took a median (10th-90th percentiles) of 12.0 (3.0-21.0) minutes versus 6.0 (3.0-21.0) minutes for distal insertion (n = 21; P= .106) to anesthetize the medial calf. Only 10 of 25 (40%) and 10 of 24 (42%) patients in the proximal and distal groups, respectively, developed anesthesia at both the medial calf and top of the patella (P= .978). Bolus-induced motor weakness occurred in 19 of 25 (76%) and 16 of 24 (67%) patients in the proximal and distal groups (P = .529). Ten of 24 patients (42%) in the distal group required intravenous morphine postoperatively, compared to 2 of 24 (8%) in the proximal group (P = .008), but there were no differences in other secondary outcomes. CONCLUSIONS: Continuous adductor canal blocks can be performed reliably at both proximal and distal locations. The proximal approach may offer minor analgesic and logistic advantages without an increase in motor block.

Continuous adductor canal blocks are superior to continuous femoral nerve blocks in promoting early ambulation after TKA.

BACKGROUND: Femoral continuous peripheral nerve blocks (CPNBs) provide effective analgesia after TKA but have been associated with quadriceps weakness and delayed ambulation. A promising alternative is adductor canal CPNB that delivers a primarily sensory blockade; however, the differential effects of these two techniques on functional outcomes after TKA are not well established. QUESTIONS/PURPOSES: We determined whether, after TKA, patients with adductor canal CPNB versus patients with femoral CPNB demonstrated (1) greater total ambulation distance on Postoperative Day (POD) 1 and 2 and (2) decreased daily opioid consumption, pain scores, and hospital length of stay. METHODS: Between October 2011 and October 2012, 180 patients underwent primary TKA at our practice site, of whom 93% (n = 168) had CPNBs. In this sequential series, the first 102 patients had femoral CPNBs, and the next 66 had adductor canal CPNBs. The change resulted from a modification to our clinical pathway, which involved only a change to the block. An evaluator not involved in the patients' care reviewed their medical records to record the parameters noted above. RESULTS: Ambulation distances were higher in the adductor canal group than in the femoral group on POD 1 (median [10(th)-90(th) percentiles]: 37 m [0-90 m] versus 6 m [0-51 m]; p < 0.001) and POD 2 (60 m [0-120 m] versus 21 m [0-78 m]; p = 0.003). Adjusted linear regression confirmed the association between adductor canal catheter use and ambulation distance on POD 1 (B = 23; 95% CI = 14-33; p < 0.001) and POD 2 (B = 19; 95% CI = 5-33; p = 0.008). Pain scores, daily opioid consumption, and hospital length of stay were similar between groups. CONCLUSIONS: Adductor canal CPNB may promote greater early postoperative ambulation compared to femoral CPNB after TKA without a reduction in analgesia. Future randomized studies are needed to validate our major findings. LEVEL OF EVIDENCE: Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

A randomized comparison of long-axis and short-axis imaging for in-plane ultrasound-guided popliteal-sciatic perineural catheter insertion.

PURPOSE: Ultrasound-guided long-axis in-plane sciatic perineural catheter insertion has been described but not validated. For the popliteal-sciatic nerve, we hypothesized that a long-axis in-plane technique, placing the catheter parallel and posterior to the nerve, results in faster onset of sensory anesthesia compared to a short-axis in-plane technique. METHODS: Preoperatively, patients receiving a popliteal-sciatic perineural catheter were randomly assigned to either the long-axis or short-axis technique. Mepivacaine 2% was administered via the catheter following insertion. The primary outcome was time to achieve complete sensory anesthesia. Secondary outcomes included procedural time, onset time of motor block, and pain on postoperative day 1. RESULTS: Fifty patients were enrolled. In the long-axis group (n = 25), all patients except 1 (4%) had successful catheter placement per protocol. Two patients (8%) in the long-axis group and 1 patient (4%) in the short-axis group (n = 25) did not achieve sensory anesthesia by 30 min and were withdrawn. Seventeen of 24 (71%) and 17 of 22 (77%) patients in the short-axis and long-axis groups, respectively, achieved the primary outcome of complete sensory anesthesia (p = 0.589). The short-axis group (n = 17) required a median (10th-90th ‰) of 18.0 (8.4-30.0) min compared to 18.0 (11.4-27.6) min for the long-axis group (n = 17, p = 0.208) to achieve complete sensory anesthesia. Procedural time was 6.5 (4.0-12.0) min for the short-axis and 9.5 (7.0-12.7) min for the long-axis (p < 0.001) group. There were no statistically significant differences in other secondary outcomes. CONCLUSION: Long-axis in-plane popliteal-sciatic perineural catheter insertion requires more time to perform compared to a short-axis in-plane technique without demonstrating any advantages.

An in vitro study to evaluate the utility of the "air test" to infer perineural catheter tip location.

Injection of air under ultrasound guidance via a perineural catheter after insertion ("air test") has been described as a means to infer placement accuracy, yet this test has never been rigorously evaluated. We tested the hypothesis that the air test predicts accurate catheter location greater than chance and determined the test's sensitivity, specificity, and positive and negative predictive values using a porcine-bovine model and blinded expert in ultrasound-guided regional anesthesia. The air test improved the expert clinician's assessment of catheter tip position compared to chance, but there was no difference when compared to direct visualization of the catheter without air injection.