INTRATRACHEAL SALINE BOLUS INCREASES SURVIVABILITY IN RABBITS EXPOSED TO LETHAL DOSE OF INHALED HYDROGEN SULFIDE

Abstract

SESSION TITLE: Pharmacotherapeutics Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: Hydrogen Sulfide (H2S) is a highly toxic, flammable, and colorless gas. In addition to industrial accident risks, H2S has been identified as a potential terrorist chemical and military threat agent for use in mass-casualty events, with no effective antidotes. In this study, we investigate the effects of a small volume of intratracheal (IT) slow-drip saline versus IT fast bolus saline treatment to prolong survival in H2S exposure in an animal model for potential treatments during mass-casualty crises. METHODS: The effects of IT saline in H2S exposure were tested on 49 New Zealand white male rabbits. Animals were anesthetized and intubated, but not ventilated. H2S gas (2000 ppm) was delivered along with a 1.5% isoflurane in air mixture (2.25 liters/min)for 30 minutes.Three groups were compared: no saline into endotracheal tube control(n=16), IT slow saline drip (n=17) and fast IT saline bolus group (n=16). Animals in IT slow drip saline group received 3cc of saline in 3 minutes, while fast saline bolus group animals received it in less than 20 seconds. Both treatment groups were compared to the control group. Systemic blood pressure and heart rate were continuously monitored.The changes in tissue oxy and deoxy hemoglobin concentrations were measured non-invasively over the brain region using continuous wave near infrared spectroscopy. Animals were deemed survivors at 60 minutes from the start of toxic exposure. Animals were sacrificed when systolic blood pressure dropped below 20 mmHg. RESULTS: The average weight for all animals(n=49) in this study was 3.88 ± 0.35 kg, mean ± SD. The survival rate of the fast saline, slow saline, and the control groups were 56.25%, and,23.53%, and 25%.Log-rank (Mantel-Cox) test showed that the survivability in the treatment groups and control groups are significantly different (p=0.0417). Slow saline group versus fast saline group difference was also significant (p=0.0140). The slow saline group compared to control group results were not different (p=0.7031). CONCLUSIONS: The rapid administration of a small volume of saline bolus given via IT route was effective in prolonging survival in lethal H2S exposure when given rapidly. These findings appear likely due to the rapid bolus stimulating cough and breathing responses in apneic animals, in contrast to the slow dripping of a similar amount of saline.While the stimulation of breathing leads to inhalation of more H2S in this model, improvement in hypoxemia in these animals appears to be of greater importance than the risk of additional H2S exposure.Thus, we propose that the hypoxemia from H2S-induced respiratory depression is a major contributor to mortality compared to the metabolic inhibition of cytochromes from H2S in this scenario. CLINICAL IMPLICATIONS: This has potential implications for the treatment victims of H2S exposure who cannot be removed from the exposure site as this commonly occurs in mass-casualty events. DISCLOSURES: No relevant relationships by vikhyat bebarta, source=Web Response No relevant relationships by Gerry Boss, source=Web Response No relevant relationships by Matthew Brenner, source=Web Response No relevant relationships by Tanya Burney, source=Web Response No relevant relationships by Adriano Chan, source=Web Response No relevant relationships by Melina Doosty, source=Web Response No relevant relationships by Philippe Haouzi, source=Web Response No relevant relationships by Tara Hendry-Hofer, source=Web Response No relevant relationships by Jangwoen Lee, source=Web Response No relevant relationships by Sari Mahon, source=Web Response No relevant relationships by David Mukai, source=Web Response No relevant relationships by George Philipopoulos, source=Web Response