359 Determination of the Carboxyhemoglobin Half Life in Carbon Monoxide Poisoned Patients Treated With High Flow Nasal Cannula Therapy

Abstract

Acute carbon monoxide poisoning is a common environmental emergency worldwide. Treatment options are limited to normobaric oxygen therapy with a non-breather face mask and hyperbaric oxygen therapy. The aim of this study is to determine the half-life of carboxyhemoglobin with a high flow nasal cannula in adult patients admitted to the emergency department with acute carbon monoxide poisoning. Device tolerability and patient comfort with the high flow nasal cannula were also evaluated. This study was conducted between January 2017 and February 2018 in 2 academic emergency departments. Venous blood samples were obtained at 10 minute intervals to determine the rate of elimination of the carbon monoxide. Patient comfort was evaluated by verbal numeric rating scale. Device tolerability was evaluated by patient requests to change the flow rate or flow temperature. The primary outcome was the determination of the half-life of carboxyhemoglobin with a high flow nasal cannula. The secondary outcome was the device tolerability and patient comfort with the high flow nasal cannula. After excluding 6 of 39 patients, a total of 33 patients were analyzed in the study. The mean baseline COHb level of the 33 patients was 22.5% (SD 8%). The mean half-life of carboxyhemoglobin was determined as 36.76 minutes (SD 9.26 min) with a high flow nasal cannula. COHb levels were halved during the first 40 minutes in 22 (66.7%) of the study patients. Twenty of the patients did not report intolerance to a high flow, with a median verbal numeric rating score of 10. Among the 11 patients who requested a change in the flow rate, the median verbal numeric rating score was 7. After decreasing the flow rate, the median verbal numeric rating score became 9. The high flow nasal cannula is an easy, safe and comfortable method to treat acute CO poisoned patients which is effective in reducing COHb half-life. HFNC may be a promising alternative method if it is validated as effective with larger studies with clinical outcomes.