Evaluation of machine learning models as decision aids for anesthesiologists.

Machine Learning (ML) models have been developed to predict perioperative clinical parameters. The objective of this study was to determine if ML models can serve as decision aids to improve anesthesiologists' prediction of peak intraoperative glucose values and postoperative opioid requirements. A web-based tool was used to present actual surgical case and patient information to 10 practicing anesthesiologists. They were asked to predict peak glucose levels and post-operative opioid requirements for 100 surgical patients with and without presenting ML model estimations of peak glucose and opioid requirements. The accuracies of the anesthesiologists' estimates with and without ML estimates as reference were compared. A questionnaire was also sent to the participating anesthesiologists to obtain their feedback on ML decision support. The accuracy of peak glucose level estimates by the anesthesiologists increased from 79.0 ± 13.7% without ML assistance to 84.7 ± 11.5% (< 0.001) when ML estimates were provided as reference. The accuracy of opioid requirement estimates increased from 18% without ML assistance to 42% (p < 0.001) when ML estimates were provided as reference. When ML estimates were provided, predictions of peak glucose improved for 8 out of the 10 anesthesiologists, while predictions of opioid requirements improved for 7 of the 10 anesthesiologists. Feedback questionnaire responses revealed that the anesthesiologist primarily used the ML estimates as reference to modify their clinical judgement. ML models can improve anesthesiologists' estimation of clinical parameters. ML predictions primarily served as reference information that modified an anesthesiologist's clinical estimate.

Quantitative Neuromuscular Monitoring in Clinical Practice: A Professional Practice Change Initiative.

BACKGROUND: Residual neuromuscular blockade can be avoided with quantitative neuromuscular monitoring. The authors embarked on a professional practice initiative to attain documented train-of-four ratios greater than or equal to 0.90 in all patients for improved patient outcomes through reducing residual paralysis. METHODS: The authors utilized equipment trials, educational videos, quantitative monitors in all anesthetizing locations, and electronic clinical decision support with real-time alerts, and initiated an ongoing professional practice metric. This was a retrospective assessment (2016 to 2020) of train-of-four ratios greater than or equal to 0.9 that were documented before extubation. Anesthesia records were manually reviewed for neuromuscular blockade management details. Medical charts of surgical patients who received a neuromuscular blocking drug were electronically searched for patient characteristics and outcomes. RESULTS: From pre- to postimplementation, more patients were assigned American Society of Anesthesiologists Physical Status III to V, fewer were inpatients, the rocuronium average dose was higher, and more patients had a prereversal train-of-four count less than 4. Manually reviewed anesthesia records (n = 2,807) had 2 of 172 (1%) cases with documentation of train-of-four ratios greater than or equal to 0.90 in November 2016, which was fewer than the cases in December 2020 (250 of 269 [93%]). Postimplementation (February 1, 2020, to December 31, 2020), sugammadex (650 of 935 [70%]), neostigmine (195 of 935 [21%]), and no reversal (90 of 935 [10%]) were used to attain train-of-four ratios greater than or equal to 0.90 in 856 of 935 (92%) of patients. In the electronically searched medical charts (n = 20,181), postimplementation inpatients had shorter postanesthesia care unit lengths of stay (7% difference; median [in min] [25th, 75th interquartile range], 73 [55, 102] to 68 [49, 95]; P < 0.001), pulmonary complications were less (43% difference; 94 of 4,138 [2.3%] to 23 of 1,817 [1.3%]; P = 0.010; -1.0% difference [95% CI, -1.7 to -0.3%]), and hospital length of stay was shorter (median [in days] [25th, 75th], 3 [2, 5] to 2 [1, 4]; P < 0.001). CONCLUSIONS: In this professional practice initiative, documentation of train-of-four ratios greater than or equal to 0.90 occurred for 93% of patients in a busy clinical practice. Return-of-strength documentation is an intermediate outcome, and only one of many factors contributing to patient outcomes.

Contrast-enhanced paravertebrogram to confirm paravertebral catheter position in elective thoracic surgery: a proof of concept study.

BACKGROUND: Paravertebral pain catheters have been shown to be equally effective as epidural pain catheters for postoperative analgesia after thoracic surgery with the possible additional benefit of less hemodynamic effect. However, a methodology for verifying correct paravertebral catheter placement has not been tested or objectively confirmed in previous studies. The aim of the current study was to describe a technique to confirm the correct position of a paravertebral pain catheter using a contrast-enhanced paravertebrogram. METHODS: A retrospective cohort proof of concept study was performed including 10 consecutive patients undergoing elective thoracic surgery with radiographic contrast-enhanced confirmation of intraoperative paravertebral catheter placement (paravertebrogram). RESULTS: The results of the paravertebrograms, which were done in the operating room at the end of the procedure, verified correct paravertebral catheter placement in 10 of 10 patients. The radiographs documented dissemination of local anesthetic within the paravertebral space. CONCLUSION: This proof of concept study demonstrated that a contrast-enhanced paravertebrogram could be used in conjunction with standard postoperative chest radiography to add valuable information for the assessment of paravertebral catheter placement. This technique has the potential to increase the accuracy and efficiency of postoperative analgesia, and to set a quality standard for future studies of paravertebral pain catheters.

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.

Comparison of continuous intravenous lidocaine versus transversus abdominis plane block for kidney transplant surgery: a randomized, non-inferiority trial.

BACKGROUND AND OBJECTIVES: Transversus abdominis plane (TAP) blocks are associated with an improvement in postoperative analgesia following kidney transplant surgery. However, these blocks carry inherent risk and require a degree of expertise to perform successfully. Continuous intravenous lidocaine may be an effective alternative. In this randomized, non-inferiority study, we hypothesized that a continuous lidocaine infusion provides similar postoperative analgesia to a TAP block. METHODS: Subjects presenting for kidney transplant surgery were randomized in a 1:1 ratio to either an ultrasound-guided unilateral, single-injection TAP block (TAP group) or a continuous infusion of lidocaine (Lido group). The primary outcome of this non-inferiority study was opioid consumption within the first 24 hours following surgery. Secondary outcomes included pain scores, patient satisfaction, opioid-related adverse events, time to regular diet, and persistent opioid use. RESULTS: One hundred and twenty subjects, 59 from the TAP group and 61 from the Lido group, completed the study per protocol. Analysis of the primary outcome showed a cumulative geometric mean intravenous morphine equivalent difference between the TAP (14.6±3.2 mg) and Lido (15.9±2.4 mg) groups of 1.27 mg (95% CI -4.25 to 6.79; p<0.001), demonstrating non-inferiority of the continuous lidocaine infusion. No secondary outcomes showed clinically meaningful differences between groups. CONCLUSIONS: This study demonstrates that a continuous infusion of lidocaine offers non-inferior postoperative analgesia compared with an ultrasound-guided unilateral, single-injection TAP block in the first 24 hours following kidney transplant surgery. TRIAL REGISTRATION NUMBER: NCT03843879.

Treatment of Chronic Abdominal Pain With 10-kHz Spinal Cord Stimulation: Safety and Efficacy Results From a 12-Month Prospective, Multicenter, Feasibility Study.

INTRODUCTION: Chronic abdominal pain (CAP) can arise from multiple conditions, including inflammatory disorders, trauma because of injury or surgery, or structural or functional causes. This prospective, single-arm study was designed to evaluate the safety and efficacy of 10-kHz spinal cord stimulation (SCS) in patients with intractable CAP over a 12-month follow-up period. METHODS: Subjects with CAP who had been refractory to conventional medical treatment for at least 3 months resulting in self-reported pain scores of ≥5 cm on a 10-cm visual analog scale were enrolled at 4 centers in the United States. Study subjects underwent a trial stimulation lasting up to 14 days with epidural leads implanted from the vertebral levels T4 through T8. Subjects who had ≥40% pain relief during the trial stimulation period were implanted with a Senza system (Nevro Corp., Redwood City, CA) and followed up to 12 months after surgery. RESULTS: Twenty-three of 24 subjects (95.8%) had a successful trial stimulation and proceeded to a permanent implant. After 12 months of treatment with 10-kHz SCS, 78.3% of subjects were responders (pain relief of ≥50%) and 14 of 22 subjects (63.6%) were remitters (sustained ≤3.0-cm visual analog scale scores). Secondary outcomes, including assessments of disability, mental and physical well-being, sleep quality, perception of improvement, and satisfaction, showed that 10-kHz SCS greatly improved the quality of life of patients with CAP. Observationally, most subjects also reported concurrent reduction or resolution of nausea and/or vomiting. DISCUSSION: 10-kHz SCS can provide durable pain relief and improve the quality of life in patients with CAP.

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 comparison of regional versus general anesthesia for ambulatory anesthesia: a meta-analysis of randomized controlled trials.

Both regional anesthesia and general anesthesia have been proposed to provide optimal ambulatory anesthesia. We searched MEDLINE and other databases for randomized controlled trials comparing regional anesthesia and general anesthesia in ambulatory surgery patients for meta-analysis. Only major conduction blocks were considered to be regional anesthesia. Regional anesthesia was further separated into central neuraxial block and peripheral nerve block. Fifteen (1003 patients) and 7 (359 patients) trials for central neuraxial block and peripheral nerve block were included in the meta-analysis. Both central neuraxial block and peripheral nerve block were associated with increased induction time, reduced pain scores, and decreased need for postanesthesia care unit analgesics. However, central neuraxial block was not associated with decreased postanesthesia care unit bypass or time or reduced nausea despite reduced analgesics, and it was associated with a 35-min increase in total ambulatory surgery unit time. In contrast, peripheral nerve block was associated with decreased postanesthesia care unit need and decreased nausea but, again, not with decreased ambulatory surgery unit time. This meta-analysis indicates potential advantages for regional anesthesia, such as decreased postanesthesia care unit use, nausea, and postoperative pain. Although these factors have been proposed to reduce ambulatory surgery unit stay, neither central neuraxial block nor peripheral nerve block were associated with reduced ambulatory surgery unit time. Other factors, such as unsuitable discharge criteria and limitations of meta-analysis, may explain this discrepancy.