High quantities: Evaluating the association between cannabis use and propofol anesthesia during endoscopy.

BACKGROUND: Endoscopy under propofol sedation has become a routine procedure. Given the number of Canadians undergoing an endoscopy annually, as well as the pervasive use of cannabis by many patients, understanding the effect of cannabis use on the propofol dose at endoscopy is highly relevant. We aimed to evaluate the association between cannabis exposure and the propofol dose needed to achieve adequate sedation at endoscopy. METHODS: A case-control study of individuals undergoing endoscopy was conducted at a single outpatient endoscopy clinic in London, Ontario between 2014 and 2017. Cases included all individuals with any self-reported cannabis exposure, while controls included all individuals without any self-reported history of cannabis use. Dose of propofol administered by a single anesthetist was collected on each subject as well as additional demographic and procedure-related covariates. RESULTS: Three hundred and eighteen participants were included (cases, n = 151; controls, n = 167). Cannabis exposure was associated with an increase in propofol dose (cases 0.33 mg/kg/minute ±0.24; controls, 0.18 mg/kg/minute ±0.11; p<0.0001). Cannabis exposure remained an independent predictor of propofol dose on multivariate linear regression accounting for other important covariates (p<0.0001). Daily cannabis users required a higher propofol dose than weekly or monthly users. Three procedural sedation-related complications occurred in the cannabis-exposed group, while none occurred in the unexposed group. CONCLUSION: Our data suggest that cannabis use is significantly associated with the quantity of propofol needed for sedation at endoscopy. Further study is needed to better understand the molecular basis for this possible drug-drug interaction.

A prospective, randomized, double-blind comparison of ultrasound-guided axillary brachial plexus blocks using 2 versus 4 injections.

INTRODUCTION: In this prospective, randomized, double-blind study, we compared the effectiveness and time efficiency of perioperative axillary blocks performed via 2 different techniques, 1 involving 2 and the other 4 separate skin punctures. METHODS: One hundred twenty patients undergoing upper limb surgery were randomized to receive either (1) an axillary brachial plexus block involving 2 injections, with 30 mL local anesthetic injected posterior to the axillary artery (with redirection, as needed, to achieve circumferential spread), plus 10 mL local anesthetic to the musculocutaneous nerve, guided by ultrasound (group 1, n = 56); or (2) 4 separate 10-mL injections to the median, ulnar, radial, and musculocutaneous nerves, using a combined ultrasound and neurostimulation technique (group 2, n = 58). All patients received 40 mL of 0.5% ropivacaine with 1:400,000 epinephrine. The primary outcome was the success rate of the block, defined as anesthesia adequate for surgery. Secondary outcomes were the time to administer the block, time to the onset of motor-sensory block, time to surgical readiness, and incidence of adverse events. RESULTS: The 2-injection technique was slightly faster to administer (8 vs 11 minutes, P = 0.003). The mean nerve block score was slightly higher for the 4-injection group at the 10-, 15-, 20-, and 30-minute time points, but the cumulative percentages of blocks having taken effect were not significantly different over these time points, at 0.0%, 5.4%, 12.5%, and 37.5% among those who had received a 2-injection block versus 6.9%, 10.4%, 19.0%, and 48.3%, respectively, with the 4-injection block (P = 0.20). There was no difference in the percentage of patients with complete block by 30 minutes (32.1% vs 37.5%, P = 0.55) or in final block success rates (89.3% vs 87.9%, P = 0.99). CONCLUSIONS: An ultrasound-guided 2-injection axillary block may be as effective as, and more time efficient than, a 4-injection technique.

Ultra low-dose naloxone and tramadol/acetaminophen in elderly patients undergoing joint replacement surgery: a pilot study.

OBJECTIVE: A pilot study was conducted to assess whether both the rationale and feasibility exist for future randomized clinical trials to evaluate the combined use of naloxone infusion and tramadol/acetaminophen as opioid-sparing drugs in elderly patients undergoing lower extremity joint replacement surgery. DESIGN: Ten patients 70 years of age or older undergoing either total knee (n=7) or total hip (n=3) arthroplasty were treated prospectively. Each patient received two tablets of tramadol/acetaminophen (Tramacet; Janssen-Ortho Inc, Canada) preoperatively and every 6 h postoperatively, as well as a naloxone infusion started preoperatively at 0.25 microg/kg/h and continued up to 48 h postoperatively. In addition, standard intraoperative care was provided with 0.2 mg of intrathecal morphine, 1.4 mL of 0.75% bupivacaine, and an intra-articular infiltration of 100 mL of 0.3% ropivacaine and 30 mg of ketorolac, as well as standard postoperative morphine via patient-controlled analgesia orders and celecoxib 200 mg twice daily for five days. OUTCOME MEASURES: Compared with seven historical controls, also 70 years of age or older, who had undergone either a total knee (n=4) or total hip (n=3) arthroplasty, postoperative opioid use was reduced by 80%. Except for transient nausea and vomiting in 40% and 20% of patients, respectively, the 10 patients on tramadol/acetaminophen and naloxone tolerated the new regimen without difficulty. CONCLUSION: Consequently, a randomized, double-blinded clinical trial comparing standard therapy versus standard therapy plus these two drugs seems warranted. In such a trial, it would require approximately 20 subjects per treatment arm to detect a 80% decrease in morphine use.

Frequency and implications of ambulatory surgery without a patient escort.

PURPOSE: A study was undertaken to identify the characteristics and outcomes of ambulatory surgical patients without an escort. CLINICAL FEATURES: During a 38-month period, the incidence of patients without an escort at one tertiary care institution was 0.2% (60/28,391). Five patients had their surgery cancelled. The other 55 patients had their surgery performed. Two groups of patients without an escort were identified: patients who were known not to have an escort preoperatively, and patients with "no show" escort. The number of patients with no show escort is much higher than the number of patients who were known not to have an escort preoperatively. The outcome of the no escort patients was compared with the matched control group of patients with an escort. There were no differences in the rates of unanticipated admission, emergency visits or read-mission into the hospital within 30 days comparing the group of patients with and without an escort. CONCLUSIONS: The absence of an escort in ambulatory surgical patients occurs in 0.2% of surgeries, and varies according to the type of service. The number of patients with no show escort is higher than the number of patients with known no escort preoperatively.

Elimination of routine testing in patients undergoing cataract surgery allows substantial savings in laboratory costs. A brief report.

PURPOSE: To evaluate the possible cost savings when routine preoperative testing is discontinued in ambulatory cataract surgery patients. METHODS: A policy was introduced at our hospital to stop routine testing in ambulatory cataract patients. Consecutive patients' medical records were analyzed in a four-month period pre- and a four-month period post-discontinuation of routine laboratory tests. Ambulatory cataract surgery is performed under topical (and sometimes retrobulbar block) anesthesia with iv sedation. Co-morbidities, perioperative events, frequency and cost of tests ordered were compared for the two groups. Average costs per patient pre- and post-discontinuation of routine tests, and total possible cost savings were calculated. RESULTS: One thousand two hundred and thirty-one patients were studied; 636 had routine laboratory tests and 595 had no routine laboratory tests. The ratios of gender, co-morbidities and perioperative events were similar in the two groups. There was a significant reduction in the number of tests ordered after the new policy was introduced, from 5.8 tests per patient to 0.4 tests per patient. The cost of tests per patient was reduced from Can $39.67 to $4.01. CONCLUSION: In ambulatory cataract surgery, over 90% savings in laboratory costs is possible after elimination of routine tests.

What is the minimum training required for successful cricothyroidotomy?: a study in mannequins.

BACKGROUND: A correctly performed cricothyroidotomy may be lifesaving in a cannot-ventilate, cannot-intubate situation. However, many practicing anesthesiologists do not have experience with cricothyroidotomy. The purpose of this study was to determine the minimum training required to perform cricothyroidotomy in 40 s or less in mannequins. METHODS: After informed consent, participants were shown a demonstration video and asked to perform 10 consecutive cricothyroidotomy procedures on a mannequin using a preassembled percutaneous dilational cricothyroidotomy set. Each attempt was timed from skin palpation to lung insufflation. Cricothyroidotomy was considered successful if it was performed in 40 s or less, and the cricothyroidotomy time was considered to have plateaued when there were no significant reductions in cricothyroidotomy times in three consecutive attempts. RESULTS: One hundred two anesthesiologists participated in the study. There was a significant reduction of cricothyroidotomy times over the 10 attempts (P < 0.0001) and between three consecutive attempts until the fourth attempt (P < 0.03). The cricothyroidotomy times plateaued by the fourth attempt, while the success rate plateaued at the fifth attempt (94, 96, 96, and 96% at the fourth, fifth, sixth, and seventh attempts, respectively). CONCLUSION: Practice on mannequins leads to reductions in cricothyroidotomy times and improvement in success rates. By the fifth attempt, 96% of participants were able to successfully perform the cricothyroidotomy in 40 s or less. While clinical correlates are not known, the authors recommend that providers of emergency airway management be trained on mannequins for at least five attempts or until their cricothyroidotomy time is 40 s or less. The most appropriate retraining intervals have yet to be determined for optimal cricothyroidotomy skill retention.

Probable gas embolism during operative hysteroscopy caused by products of combustion.

PURPOSE: Gas embolism is a rare but well documented entity during operative hysteroscopy, with an incidence of 10-50%. Catastrophic outcomes occur at a rate of three in 17,000 procedures. The purpose of this report is to present a non-fatal case of gas embolism probably caused by the gaseous products of combustion. CLINICAL FEATURES: A 50-yr-old woman with a history of menorrhagia was scheduled for hysteroscopy and endometrial ablation and polypectomy. Fifteen minutes into the procedure, with the patient in lithotomy position, 20 degree head down tilt, and breathing spontaneously, a sudden oxygen desaturation occurred from 97% to 87%. The patient's end-tidal carbon dioxide dropped from 46 mmHg to 27 mmHg. The patient's breathing pattern remained normal, respiratory rate remained 11-12 breaths x min(-1) but amplitude of the reservoir bag movement was increased. Cardiovascular variables remained stable. She responded rapidly to 100% oxygen and made an uneventful recovery. Having ruled out other possible causes, we concluded gas embolism was responsible for the fall in oxygen saturation and end-tidal CO(2). CONCLUSION: With all the precautions in place to minimize the likelihood of fluid overload and ambient air embolism occurring, we surmised that products of combustion were the cause of the gas embolism. During endometrial ablation, gaseous products of combustion, mainly carbon dioxide, accumulate. The gases may then contribute to the rise in uterine pressure that occurs as irrigation fluid enters the uterus and this rise in pressure in turn encourages passage of gas into the open venous sinuses.

Risk factors for prolonged stay after ambulatory surgery: economic considerations.

The risk factors that prolong length of stay of ambulatory patients can be classified as preoperative, intraoperative, and postoperative. Preoperative factors include the type of surgery, ear, nose and throat and strabismus surgery, old age and pre-existing congestive heart failure. Intraoperative factors include increasing length of surgery, and general anesthesia, while postoperative factors include postoperative nausea and vomiting, excessive pain and adverse cardiovascular events. The factors that anesthesiologists can address to reduce length of stay are postoperative nausea and vomiting and excessive pain. Multimodal management of postoperative nausea and vomiting and pain can minimize adverse events and thereby reduce length of stay in the postanesthetic care unit, but will not necessarily lead to a reduction in staffing levels. As personnel costs contribute the majority of postanesthetic care unit costs, more than 95%, direct financial savings may not be possible from eliminating adverse events alone. Optimizing the use of the postanesthetic care unit and reducing total hours in the unit with higher operating room turnover may lead to indirect financial benefits.