A novel preclinical model of fentanyl-induced cardiorespiratory collapse to investigate resuscitation outcomes

Abstract

Introduction: Opioid-related morbidities have become a critical public health concern, with ultrapotent synthetic opioids (UPSO) such as fentanyl contributing to the rise in opioid-related fatalities. Respiratory depression is the cardinal trait of fentanyl overdose, leading to systemic hypoxia and subsequent cardiorespiratory collapse (CRC). There is growing recognition that fentanyl induced CRC (fiCRC) is unique from other forms of sudden CRC. Yet, the consequences of fiCRC and its reversal remain poorly understood. This is due in part to the limited preclinical studies investigating rescue from fiCRC. Objective: using a novel model of fiCRC and subsequent reversal, this ongoing study aims to define the impact of UPSO and naloxone rescue on in vivo survival outcomes. Methods and Results: Male and female C57BL/6J mice were used. UPSO fentanyl i.v. administration (30 to 500 mcg/kg) suppressed breathing and subsequently led to fiCRC. The return of spontaneous circulation (ROSC) was achieved by performing manual chest compressions in combination of epinephrine administration after 8 minutes of fiCRC. In subset of mice, naloxone was administered post ROSC. Outcomes after 72 hours were accessed. The latency of fiCRC (mean arterial pressure at 40 mmHg) exhibited a negative correlation with the doses of fentanyl administered. Resuscitation from fiCRC was unreliable across the dose spectrum, while naloxone consistently rescued the majority of fiCRC animals. Naloxone increased ROSC rate from 54% to 86% when the dose of fentanyl was 30 mcg/Kg (n=22). With naloxone rescue, we compared fiCRC with non-opioid-induced cardiac arrest followed by potassium chloride injection (0.8 mg/g). Both models showed severe lung edema as evidenced by Evans Blue staining. However, the lung wet/dry weight ratio was higher in fiCRC group than in the non-opioid treatment group (5.50±0.05 vs. 6.60±0.60, n=4, p<0.05). Survival in fiCRC group was significantly worse than in non-opioid treatment group (survival rate: 25% vs. 83%, n=17, p<0.05). Conclusions: Our study highlights two important findings. First, the reliable resuscitation of fiCRC necessitates the use of naloxone. Second, the likelihood of injury is significant following successful rescue from fiCRC by naloxone. Our continued work using this fiCRC model will lead to insights that can be leveraged for strategies to mitigate injury and improve survival following fentanyl overdose. R01 HL163965 & R01 DA057767. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.