Background The Infiltration between the Popliteal Artery and Capsule of the Knee (IPACK) block is a new anesthesiologist- administered analgesic technique for controlling posterior knee pain that has not yet been well studied in total knee arthroplasty (TKA) patients. We compared pain outcomes in TKA patients before and after implementation of the IPACK with the hypothesis that patients receiving IPACK blocks will report lower pain scores on postoperative day (POD) 0 than non-IPACK patients. Methods With Institutional Review Board approval, we retrospectively reviewed data for consecutive TKA patients by a single surgeon 4 months before (PRE) and after (POST) IPACK implementation. All TKA patients received adductor canal catheters and peri-operative multimodal analgesia. The primary outcome was pain on POD 0. Other outcomes were daily pain scores, opioid consumption, ambulation distance, length of stay, and adverse events within 30 days. Results Post-implementation, 48/50 (96%) of TKA patients received an IPACK block, and they were compared with 32 patients in the PRE group. On POD 0, the lowest pain score (median [10th–90th percentiles]) was significantly lower for the POST group compared to the PRE group (0 [0–4.3] vs. 2.5 [0–7]; P = 0.003). The highest patient-reported pain scores on any POD were similar between groups with no differences in other outcomes. Conclusions Within a multimodal analgesic protocol, addition of IPACK blocks decreased the lowest pain scores on POD 0. Although other outcomes were unchanged, there may be a role for new opioid-sparing analgesic techniques, and changing clinical practice change can occur rapidly.

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.

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.

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.