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

Color Doppler ultrasonography of an agitated solution is predictive of accurate catheter placement for a continuous popliteal sciatic nerve block

Background

Continuous peripheral nerve catheters (PNCs) have been shown to provide superior postoperative analgesia, decrease opioid consumption, and improve patient satisfaction compared with single injection techniques. In order to achieve success and reliability, accurate catheter positioning is an essential element of PNC placement. An agitated solution of normal saline, D5W, or a local anesthetic solution can be produced by the introduction of air to the injectate, creating air bubbles that can enhance ultrasonographic visualization and possibly improve block success.

Methods

Eighty-three patients were enrolled. Ultrasound-guided continuous popliteal sciatic nerve blocks were performed by positioning the tip of a Tuohy needle between the tibial and common peroneal branches of the sciatic nerve and threading a catheter. An agitated local anesthetic solution was injected through the catheter, viewed with color Doppler ultrasound and video recorded. A peripheral block score (lower score = greater blockade, range 0-14) was calculated based upon the motor and sensory testing at 10, 20, and 30 min after block completion. The color Doppler agitation coverage pattern for the branches of the sciatic nerve was graded as follows: complete (> 50%), partial (> 0%, ≤ 50%), or none (0%).

Results

The degree of nerve blockade at 30 min as judged by median (10th, 90th percentile) peripheral block score was significant for partial or complete color Doppler coverage of the sciatic nerve injectate compared to no coverage [3 (0, 7) vs 8 (4, 14); p < 0.01] and block onset was faster (p = 0.03). The block success was higher in groups with partial or complete coverage of the branches of the sciatic nerve vs no coverage (96% vs 70%; p = 0.02).

Conclusions

Injection of an agitated solution through a popliteal sciatic perineural catheter is predictive of accurate catheter placement when partial or complete coverage of the sciatic nerve branches is visualized with color Doppler ultrasound.

Trial registration

NCT01591603

Regional anesthesiological support for the implementation of surgical interventions in the abdomen of dogs

Widespread use of surgical interventions in the abdomen of dogs determines the relevance of the study. The research tested the influence of therapeutic epidural blockade with 0.2% bupivacaine after surgical interventions on the background of potentiated local anaesthesia on the body of clinically healthy dogs undergoing ovariohysterectomy. In the control group postoperative analgesia was performed with the nonsteroidal anti-inflammatory drug rimadyl on the background of potentiated thiopental anaesthesia. Wound healing rates were determined in 10 animals of both control and experimental groups; blood counts and the level of inflammatory response were indicated in 5 animals of each group. The dynamics of reparative processes and complete wound healing in dogs of the experimental group occurred earlier than in animals of the control group, which confirmed the fact that the use of bupivacaine had a beneficial effect on tissue regeneration. The results of morphological and biochemical parameters of blood in animals of the experimental group manifested only an increase of leukocytes by 1.58 times, fibrinogen by 2.02 times, while in dogs of the control group the level of erythrocytes, haemoglobin and hematocrit decreased, leukocytes increased by 1.74 times, platelets decreased by 2.87 times and fibrinogen increased by 1.72 times. Among the stress response markers in the control group there was a 1.94 times increase in glucose level after surgery. In the experimental group there was a decrease in the intensity of the inflammatory reaction in dogs, accompanied by an increase of anti-inflammatory interleukin 4 (IL-4) only on the seventh day – 1.86 times, while in the control group the level of anti-inflammatory interleukin 1 receptor antagonist (IL-1RA) after three days increased by 2.30 times, after seven days – by 2.48 times, and the level of proinflammatory interleukin 6 (IL-6) after surgery increased by 2.57 times. It will be promising to conduct further research on the influence of therapeutic blockades with bupivacaine in animals in cases of various surgical interventions and pathological conditions, which will lead to faster recovery of animals and alleviate pathological processes.

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.

Simulation in teaching regional anesthesia: current perspectives

The emerging subspecialty of regional anesthesiology and acute pain medicine represents an opportunity to evaluate critically the current methods of teaching regional anesthesia techniques and the practice of acute pain medicine. To date, there have been a wide variety of simulation applications in this field, and efficacy has largely been assumed. However, a thorough review of the literature reveals that effective teaching strategies, including simulation, in regional anesthesiology and acute pain medicine are not established completely yet. Future research should be directed toward comparative-effectiveness of simulation versus other accepted teaching methods, exploring the combination of procedural training with realistic clinical scenarios, and the application of simulation-based teaching curricula to a wider range of learner, from the student to the practicing physician.