Physiologic oxygen responses to smoking opioids: an observational study using continuous pulse oximetry at overdose prevention services in British Columbia, Canada.

BACKGROUND: In British Columbia, Canada, smoking is the most common modality of drug use among people who die of opioid toxicity. We aimed to assess oxygen saturation (SpO2) while people smoked opioids during a pilot study that introduced continuous pulse oximetry at overdose prevention services (OPS) sites. METHODS: This was an observational cohort study, using a participatory design. We implemented our monitoring protocol from March to August 2021 at four OPS. We included adults (≥ 18 years) presenting to smoke opioids. A sensor taped to participants' fingers transmitted real-time SpO2 readings to a remote monitor viewed by OPS staff. Peer researchers collected baseline data and observed the timing of participants' inhalations. We analyzed SpO2 on a per-event basis. In mixed-effects logistic regression models, drop in minimum SpO2 ≤ 90% in the current minute was our main outcome variable. Inhalation in that same minute was our main predictor. We also examined inhalation in the previous minute, cumulative inhalations, inhalation rate, demographics, co-morbidities, and substance use variables. RESULTS: We recorded 599 smoking events; 72.8% (436/599) had analyzable SpO2 data. Participants' mean age was 38.6 years (SD 11.3 years) and 73.1% were male. SpO2 was highly variable within and between individuals. Drop in SpO2 ≤ 90% was not significantly associated with inhalation in that same minute (OR: 1.2 [0.8-1.78], p = 0.261) or inhalation rate (OR 0.47 [0.20-1.10], p = 0.082). There was an association of SpO2 drop with six cumulative inhalations (OR 3.38 [1.04-11.03], p = 0.043); this was not maintained ≥ 7 inhalations. Demographics, co-morbidities, and drug use variables were non-contributory. CONCLUSIONS: Continuous pulse oximetry SpO2 monitoring is a safe adjunct to monitoring people who smoke opioids at OPS. Our data reflect challenges of real-world monitoring, indicating that greater supports are needed for frontline responders at OPS. Inconsistent association between inhalations and SpO2 suggests that complex factors (e.g., inhalation depth/duration, opioid tolerance, drug use setting) contribute to hypoxemia and overdose risk while people smoke opioids.

Feeling safer: effectiveness, feasibility, and acceptability of continuous pulse oximetry for people who smoke opioids at overdose prevention services in British Columbia, Canada.

BACKGROUND: Smoking is the most common mode of unregulated opioid consumption overall and implicated in fatal overdoses in British Columbia (BC). In part, perception of decreased risk (e.g., fewer who smoke carry naloxone kits) and limited smoking-specific harm reduction services contribute to overdose deaths. Overdose prevention services (OPS) offer supervised settings for drug use. Continuous pulse oximetry, common in acute care, allows real-time, remote oxygen monitoring. We evaluated the effectiveness of a novel continuous pulse oximetry protocol aimed at allowing physical distancing (as required by COVID-19, secluded spaces, and to avoid staff exposure to vaporized opioids), its feasibility, and acceptability at OPS for people who smoke opioids. METHODS: This was a mixed methods survey study. We developed a continuous pulse oximetry protocol in collaboration with clinical experts and people with lived/living experience of substance use. We implemented our protocol from March to August 2021 at four OPS in BC permitting smoking. We included adults (≥ 18 years) presenting to OPS to smoke opioids. Peer researchers collected demographic, health, and substance use information, and conducted structured observations. OPS clients participating in our study, OPS staff, and peer researchers completed post-monitoring surveys. We analyzed responses using a thematic inductive approach and validated themes with peer researchers. RESULTS: We included 599 smoking events. OPS clients participating in our study had a mean age of 38.5 years; 73% were male. Most (98%) reported using "down", heroin, or fentanyl; 48% concurrently used other substances (32% of whom reported stimulants); 76% reported smoking alone in the last 3 days; and 36% reported an overdose while smoking. Respondents reported that the protocol facilitated physical distancing, was easy to use, high satisfaction, improved confidence, improved sense of safety, and that they would use it again. CONCLUSIONS: Continuous pulse oximetry allowed safe physical distancing, was feasible, and acceptable in monitoring people who smoke opioids at OPS.

Core competencies of peer workers who use pulse oximeters to supplement their overdose response in British Columbia.

INTRODUCTION: Peer workers (those with lived/living experience of substance use) are at the forefront of overdose response initiatives in British Columbia, Canada. The onset of the coronavirus disease pandemic has significantly compounded the impact of the overdose crisis. Peer workers are integral in supporting people who use substances. However, despite the important work they do, peer workers often lack formalized credibility and do not have the same resources available to them as service providers without lived experience. The peer-led project titled the Peer2Peer Project implemented several support programs for peer workers, including providing pulse oximeters to peer workers to supplement their overdose response procedures. MATERIALS AND METHODS: This study was a component of a larger evaluation of the pulse oximeter program at two organizations in BC. The study aims to highlight the competencies of peer workers who use pulse oximeters. Telephone interviews were conducted with seven peer workers who were given pulse oximeters. The transcripts were thematically coded using Covert et al.'s framework of core competencies of community health workers to compare our sample with other widely recognized professions. FINDINGS: We found that peer workers who used pulse oximeters described several core competencies in their work and these were aligned with Covert et al.'s core competencies for community health workers, including assessment, community health practice, communication, diversity and inclusion, professional practice, and disease prevention and management. CONCLUSION: By aligning peer workers' skills to those of community health workers, we create awareness on the competencies of peer workers in using oximeters to supplement overdose response and advocate for them to receive more recognition and respect within the workplace. Further, our findings act as groundwork for future research in identifying the professional proficiencies of peer workers.

Interference of ketone bodies on laboratory creatinine measurement in children with DKA: a call for change in testing practices.

BACKGROUND: The presence of ketone bodies (KBs) can interfere with creatinine (Cr) measurement in both enzymatic and Jaffe methods. Since a high proportion of children hospitalized for diabetic ketoacidosis (DKA) develop acute kidney injury (AKI), here we investigate whether KB interferences affect the accuracy of pediatric Cr measurement. METHODS: Residual patient plasma samples were pooled to make three Cr levels (~ 50, 100, and 250 µM). KBs (acetone, acetoacetate, and ß-hydroxybutyrate) were used to spike the pooled samples. All samples were measured for Cr by two enzymatic methods (E1 and E2), two Jaffe methods (J1 and J2), and LC-MS/MS. LC-MS/MS was considered the gold standard, and the % difference in Cr concentration was calculated for each method. RESULTS: E1 and E2 were unaffected by the presence of all three KBs. J1 and J2 were unaffected by the presence of ß-hydroxybutyrate. The presence of acetone resulted in dose-dependent positive interference in both Jaffe methods, whereas the presence of acetoacetate resulted in dose-dependent positive and negative interference in J1 and J2, respectively. CONCLUSIONS: Compared to the enzymatic methods, the Jaffe methods were much more susceptible to interference by acetone and acetoacetate, especially at lower Cr values which are commonly seen in pediatrics. Interpretation of changes in Cr concentration between different hospitals when transferring patients can become ambiguous and true kidney function unclear if different methods are used without awareness of method-specific biases. To improve DKA patient care, we recommend standardizing all of the Cr methods to an enzymatic method. A higher resolution version of the Graphical abstract is available as Supplementary information.

Closed-loop optogenetic activation of peripheral or central neurons modulates feeding in freely moving Drosophila.

Manipulating feeding circuits in freely moving animals is challenging, in part because the timing of sensory inputs is affected by the animal's behavior. To address this challenge in Drosophila, we developed the Sip-Triggered Optogenetic Behavior Enclosure ('STROBE'). The STROBE is a closed-looped system for real-time optogenetic activation of feeding flies, designed to evoke neural excitation coincident with food contact. We previously demonstrated the STROBE's utility in probing the valence of fly sensory neurons (Jaeger et al., 2018). Here we provide a thorough characterization of the STROBE system, demonstrate that STROBE-driven behavior is modified by hunger and the presence of taste ligands, and find that mushroom body dopaminergic input neurons and their respective post-synaptic partners drive opposing feeding behaviors following activation. Together, these results establish the STROBE as a new tool for dissecting fly feeding circuits and suggest a role for mushroom body circuits in processing naïve taste responses.

A complex peripheral code for salt taste in Drosophila.

Each taste modality is generally encoded by a single, molecularly defined, population of sensory cells. However, salt stimulates multiple taste pathways in mammals and insects, suggesting a more complex code for salt taste. Here, we examine salt coding in Drosophila. After creating a comprehensive molecular map comprised of five discrete sensory neuron classes across the fly labellum, we find that four are activated by salt: two exhibiting characteristics of 'low salt' cells, and two 'high salt' classes. Behaviorally, low salt attraction depends primarily on 'sweet' neurons, with additional input from neurons expressing the ionotropic receptor IR94e. High salt avoidance is mediated by 'bitter' neurons and a population of glutamatergic neurons expressing Ppk23. Interestingly, the impact of these glutamatergic neurons depends on prior salt consumption. These results support a complex model for salt coding in flies that combinatorially integrates inputs from across cell types to afford robust and flexible salt behaviors.