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.

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.

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.

Effect of return hospital visits on economics of ambulatory surgery

This review examines the effect of unanticipated admission, return hospital visits and readmission on the economics of ambulatory surgery. The overall rate of unanticipated admission was approximately 1% and the overall rate of readmission to hospital was approximately 1%. Ambulatory surgery allows total cost savings of 20-50% when compared with inpatient surgery. If 98% of ambulatory surgery patients experience uneventful recovery, the decrease in cost savings caused by unanticipated admission and return hospital visit is very small. Modifications of anesthesia and surgical technique can help to further reduce the incidence of unanticipated admission or readmission to hospital.