Rigidity, dyskinesia and other atypical overdose presentations observed at a supervised injection site, Vancouver, Canada

Mai-Lei Woo Kinshella,Mark Lysyshyn,Tim Gauthier

doi:10.1186/s12954-018-0271-5

Abstract

ObjectiveIn midst of the overdose crisis, the clinical features of opioid overdoses seem to be changing. Understanding of the adverse effects of synthetic opioids such as fentanyl is currently limited to clinical settings. Insite, a supervised injection site in Vancouver, Canada, provides an opportunity to better understand illicit drug overdose presentations.MethodsA review of clinical records at Insite for October 2016 to April 2017 was undertaken to quantify atypical overdose presentations. Overdose reports were reviewed for the number of atypical opioid overdose presentations, temporal trends over the study period, concurrent symptoms, and interventions employed by staff.ResultsInsite staff responded to 1581 overdoses during the study period, including 497 (31.4%) that did not fit a typical presentation for opioid overdoses. Of these, 485 fit into five categories of atypical features: muscle rigidity, dyskinesia, slow or irregular heart rate, confusion, and anisocoria. Muscle rigidity was the most common atypical presentation, observed in 240 (15.2%) of the overdose cases, followed by dyskinesia, observed in 150 (9.2%). Slow or irregular heart rate was observed in 69 (4.4%) cases, confusion in 24 (1.5%), and anisocoria in 2 (0.1%) of overall overdose cases.DiscussionThe similarity of atypical overdose cases at Insite with anesthesiology case reports supports the understanding that the illicit drug supply is contaminated by fentanyl and other synthetic opioids. Atypical overdose presentations can affect clinical overdose response. The experience at Insite highlights the potential for supervised consumption sites to be innovative spaces for community learning and knowledge translation.

Highlights

Insite, North America’s first legal supervised injection site, is located in the Downtown Eastside neighborhood of Vancouver, Canada
While the total number of overdoses per month peaked in December 2016, the proportion of atypical overdose presentations per month appeared to increase over the study period (Table 1)
The number of overdose presentations at Insite has been increasing in recent years but this study was conducted during a period of time when British Columbia was experiencing a surge in overdose deaths, which peaked in December 2016, and where in addition to fentanyl, carfentanyl was increasingly detected across the province, which may have influenced these findings [22, 23]

Summary

Introduction

North America’s first legal supervised injection site, is located in the Downtown Eastside neighborhood of Vancouver, Canada. While opioid overdoses typically feature pinpoint pupils, respiratory depression, and unconsciousness [4], Insite nurses and staff observed atypical overdose presentations including muscle rigidity, stiff posturing, chest wall and jaw rigidity, dyskinesia, low or irregular heart rate, confusion or delirium, and anisocoria or unequal pupils. Dyskinesia reflected a spectrum of involuntary muscle movements ranging from myoclonic jerks and twitches to more severe cases of chorea including uncontrollable flailing of limbs, and rolling around on the floor. Some of these atypical overdose features presented without other typical opioid overdose characteristics, which caused a delay for staff to recognize these events as opioid overdoses

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Discussion

Conclusion