BACKGROUND: New catheter-over-needle (CON) technology for continuous peripheral nerve blockade has emerged, but its effect on the risk of perineural catheter tip dislocation is unknown. Less flexible catheters may be more likely to migrate away from the nerve with simulated patient movement. In the present study, we evaluated catheter tip migration between CON catheters and traditional catheter-through-needle (CTN) catheters during ultrasound-guided short-axis in-plane (SAX-IP) insertion. METHODS: We evaluated the migration of popliteal-sciatic catheters in a prone, unembalmed male cadaver. Thirty catheter placement trials were divided randomly into two groups based on the catheter type: CON or CTN. A single anesthesiology resident placed the catheters by SAX-IP insertion, and the catheters were then examined by ultrasound before and after ipsilateral knee range of motion (ROM) exercises (0°–130° flexion). A blinded expert regional anesthesiologist performed caliper measurements on the ultrasound images before and after the ROM exercises. The primary outcome was the change in distance from the catheter tip to the center of the nerve (cm) between before and after the ROM exercises. RESULTS: The change in the tip-to-nerve distance (median [10th–90th percentile]) was 0.06 (−0.16 to 0.23) cm for the CTN catheter and 0.00 (−0.12 to 0.69) for the CON catheter (P = 0.663). However, there was a statistically significant increase in dislocation out of the nerve compartment for the CON catheter (4/15; 0/15 for CTN) (P = 0.043). CONCLUSIONS: Although the use of different catheter designs had no effect on the change in the measured migration distance of popliteal-sciatic catheters, 27% of the CON catheters were dislocated out of the nerve compartment. These results may influence the choice of catheter design when using SAX-IP perineural catheter insertion.
Anesthesia, Conduction ; Anesthesiology ; Cadaver* ; Catheters* ; Dislocations* ; Exercise ; Humans ; Knee ; Male ; Nerve Block ; Peripheral Nerves ; Range of Motion, Articular ; Sciatic Nerve ; Ultrasonography

BACKGROUND: Both neuraxial and peripheral regional analgesic techniques offer postoperative analgesia for total hip arthroplasty (THA) patients. While no single technique is preferred, quadriceps muscle weakness from peripheral nerve blocks may impede rehabilitation. We designed this study to compare postoperative ambulation outcome in THA patients who were treated with a new ultrasound-guided fascia iliaca catheter (FIC) technique or intrathecal morphine (ITM). METHODS: We reviewed the electronic health records of a sequential series of primary unilateral THA patients who were part of a standardized clinical pathway; apart from differences in regional analgesic technique, all other aspects of the pathway were the same. Our primary outcome was total ambulation distance (meters) combined for postoperative days 1 and 2. Secondary outcomes included daily opioid consumption (morphine milligram equivalents) and analgesic-related side effects. We examined the association between the primary outcome and analgesic technique by performing crude and adjusted ordinary least-squares linear regression. A P value < 0.05 was considered statistically-significant. RESULTS: The study analyzed the records of 179 patients (fascia iliaca, n = 106; intrathecal, n = 73). The primary outcome (total ambulation distance) did not differ between the groups (P = 0.08). Body mass index (BMI) was the only factor (β = -1.7 [95% CI -0.5 to -2.9], P < 0.01) associated with ambulation distance. Opioid consumption did not differ, while increased pruritus was seen in the intrathecal group (P < 0.01). CONCLUSIONS: BMI affects postoperative ambulation outcome after hip arthroplasty, whereas the type of regional analgesic technique used does not. An ultrasound-guided FIC technique offers similar analgesia with fewer side effects when compared with ITM.
Analgesia ; Anesthesia, Conduction ; Anesthesia, Spinal ; Arthroplasty ; Arthroplasty, Replacement, Hip* ; Body Mass Index ; Catheters* ; Critical Pathways* ; Electronic Health Records ; Fascia* ; Hip ; Humans ; Linear Models ; Morphine ; Nerve Block ; Peripheral Nerves ; Pruritus ; Quadriceps Muscle ; Rehabilitation ; Ultrasonography ; Walking

BACKGROUND: Malignant hyperthermia is a rare but potentially fatal complication of anesthesia, and several different cognitive aids designed to facilitate a timely and accurate response to this crisis currently exist. Eye tracking technology can measure voluntary and involuntary eye movements, gaze fixation within an area of interest, and speed of visual response and has been used to a limited extent in anesthesiology. METHODS: With eye tracking technology, we compared the accessibility of five malignant hyperthermia cognitive aids by collecting gaze data from twelve volunteer participants. Recordings were reviewed and annotated to measure the time required for participants to locate objects on the cognitive aid to provide an answer; cumulative time to answer was the primary outcome. RESULTS: For the primary outcome, there were differences detected between cumulative time to answer survival curves (P < 0.001). Participants demonstrated the shortest cumulative time to answer when viewing the Society for Pediatric Anesthesia (SPA) cognitive aid compared to four other publicly available cognitive aids for malignant hyperthermia, and this outcome was not influenced by the anesthesiologists’ years of experience. CONCLUSIONS: This is the first study to utilize eye tracking technology in a comparative evaluation of cognitive aid design, and our experience suggests that there may be additional applications of eye tracking technology in healthcare and medical education. Potentially advantageous design features of the SPA cognitive aid include a single page, linear layout, and simple typescript with minimal use of single color blocking.
Anesthesia ; Anesthesiology ; Delivery of Health Care ; Education, Medical ; Eye Movements ; Malignant Hyperthermia* ; Volunteers

BACKGROUND: Despite the benefits of continuous peripheral nerve blocks, catheter dislodgment remains a major problem, especially in the ambulatory setting. However, catheter dressing techniques to prevent such dislodgment have not been studied rigorously. We designed this simulation study to test the strength of two commercially available catheter dressings. METHODS: Using a cadaver model, we randomly assigned 20 trials to one of two dressing techniques applied to the lateral thigh: 1) clear adhesive dressing alone, or 2) clear adhesive dressing with an anchoring device. Using a digital luggage scale attached to a loop secured by the dressing, the same investigator applied steadily increasing force with a downward trajectory towards the floor until the dressing was removed or otherwise disrupted. RESULTS: The weight, measured (median [10th–90th percentile]) at the time of dressing disruption or removal, was 1.5 kg (1.3–1.8 kg) with no anchoring device versus 4.9 kg (3.7–6.5 kg) when the dressing included an anchoring device (P < 0.001). CONCLUSIONS: Based on this simulation study, using an anchoring device may help prevent perineural catheter dislodgement and therefore premature disruption of continuous nerve block analgesia.
Adhesives ; Analgesia ; Anesthesia, Conduction ; Bandages* ; Cadaver ; Catheters* ; Humans ; Nerve Block ; Peripheral Nerves* ; Research Personnel ; Thigh

BACKGROUND: Anesthesiologists who have finished formal training and want to learn ultrasound-guided regional anesthesia (UGRA) commonly attend 1 day workshops. However, it is unclear whether participation actually changes clinical practice. We assessed change implementation after completion of a 1 day simulation-based UGRA workshop. METHODS: Practicing anesthesiologists who participated in a 1 day UGRA course from January 2012 through May 2014 were surveyed. The course consisted of clinical observation of UGRA procedures, didactic lectures, ultrasound scanning, hands-on perineural catheter placement, and mannequin simulation. The primary outcome was the average number of UGRA blocks per month reported at follow-up versus baseline. Secondary outcomes included preference for ultrasound as the nerve localization technique, ratings of UGRA teaching methods, and obstacles to performing UGRA. RESULTS: Survey data from 46 course participants (60% response rate) were included for analysis. Participants were (median [10th–90th percentile]) 50 (37–63) years old, had been in practice for 17 (5–30) years, and were surveyed 27 (10–34) months after their UGRA training. Participants reported performing 24 (4–90) blocks per month at follow-up compared to 10 (2–24) blocks at baseline (P < 0.001). Compared to baseline, more participants at follow-up preferred ultrasound for nerve localization. The major obstacle to implementing UGRA in clinical practice was time pressure. CONCLUSIONS: Participation in a 1 day simulation-based UGRA course may increase UGRA procedural volume by practicing anesthesiologists.
Anesthesia, Conduction* ; Catheters ; Education ; Follow-Up Studies ; Lectures ; Manikins ; Nerve Block ; Teaching ; Ultrasonography

BACKGROUND: Virtual reality (VR) distraction is a nonpharmacological method to prevent acute pain that has not yet been thoroughly explored for anesthesiology. We present our experience using VR distraction to decrease routine intravenous sedation for patients undergoing preoperative perineural catheter insertion. METHODS: This 1-month quality improvement project involved all elective unilateral primary total knee arthroplasty patients who received a preoperative adductor canal catheter. Clinical data were analyzed retrospectively. For the first half of the month, all patients received usual care; intravenous sedation was administered at the discretion of the regional anesthesiologist. For the second half of the month, patients were offered VR distraction with intravenous sedation upon request. The primary outcome was fentanyl dosage; other outcomes included midazolam dosage, procedure-related pain, procedural time, and blood pressure changes. RESULTS: Seven patients received usual care and seven used VR. In the VR group, 1/7 received intravenous sedation versus 6/7 who received usual care (P = 0.029). The fentanyl dose was lower (median [10th–90th percentiles]) in the VR group (0 [0–20] µg) versus the non-VR group (50 [30–100] µg; P = 0.008). Midazolam use was lower in the VR group (0 [0–0] mg) than in the non-VR group (1 [0–1] mg; P = 0.024). Procedure-related pain was lower in the VR group (1 [1–4] NRS) versus the non-VR group (3 [2–6] NRS; P = 0.032). There was no difference in other outcomes. CONCLUSIONS: VR distraction may provide an effective nonpharmacological alternative to intravenous sedation for the ultrasound-guided placement of certain perineural catheters.
Acute Pain ; Analgesics, Opioid ; Anesthesia, Conduction ; Anesthesiology ; Arthroplasty, Replacement, Knee ; Blood Pressure ; Catheters* ; Fentanyl ; Humans ; Methods ; Midazolam ; Quality Improvement ; Retrospective Studies* ; Ultrasonography

BACKGROUND: Adductor canal catheters offer advantages over femoral nerve catheters for knee replacement patients because they produce less quadriceps muscle weakness; however, applying adductor canal catheters in bedside clinical practice remains challenging. There is currently no patient-reported outcome that accurately predicts patients' physical function after knee replacement. The present study evaluates the validity of a relatively new patient-reported outcome, i.e., a numbness score obtained using a numeric rating scale, and assesses its predictive value on postoperative ambulation. METHODS: We conducted a retrospective cohort study pooling data from two previously-published clinical trials using identical research methodologies. Both studies recruited patients undergoing knee replacement; one studied adductor canal catheters while the other studied femoral nerve catheters. Our primary outcome was patient-reported numbness scores on postoperative day 1. We also examined postoperative day 1 ambulation distance and its association with postoperative numbness using linear regression, adjusting for age, body mass index, and physical status. RESULTS: Data from 94 subjects were included (femoral subjects, n = 46; adductor canal subjects, n = 48). Adductor canal patients reported decreased numbness (median [10th-90th percentiles]) compared to femoral patients (0 [0-5] vs. 4 [0-10], P = 0.001). Adductor canal patients also ambulated seven times further on postoperative day 1 relative to femoral patients. There was a significant association between postoperative day 1 total ambulation distance and numbness (Beta = -2.6; 95% CI: -4.5, -0.8, P = 0.01) with R2 = 0.1. CONCLUSIONS: Adductor canal catheters facilitate improved early ambulation and produce less patient-reported numbness after knee replacement, but the correlation between these two variables is weak.
Arthroplasty* ; Body Mass Index ; Catheters* ; Cohort Studies ; Early Ambulation ; Femoral Nerve ; Humans ; Hypesthesia* ; Knee* ; Linear Models ; Nerve Block* ; Quadriceps Muscle ; Retrospective Studies ; Walking*