Carbon Monoxide Monitoring and Emergency Treatment

Study Overview
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Brief Summary
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Carbon monoxide (CO) has been called a silent killer, and those patients who survive CO poisoning are at risk of neurological damage, which may be permanent. CO is a leading cause of unintentional poisoning deaths in the United States, and the odorless gas results in an estimated average of 20,636 emergency department (ED) visits each year. Oxygen is the antidote for CO poisoning, and it acts both by attenuating toxic effects and enhancing elimination. A fractional inspired concentration of oxygen (FiO2) of 0.7 to 0.9 may be achieved by administration of 100% oxygen delivered using a reservoir with a facemask that prevents rebreathing. Hyperbaric oxygen therapy may provide added benefit for patients with CO poisoning, but this therapy is unavailable in many parts of the United States including Vermont. Use of a continuous positive airway pressure (CPAP) mask may achieve an FiO2 of 1.0, but the effects of delivering an FiO2 of 1.0 compared to 0.7 in CO poisoning are unknown. CPAP, by comparison, is inexpensive, portable, and available in most EDs. In this study, the investigators are testing the hypothesis that oxygen delivered by CPAP will improve both CO washout kinetics and functional outcomes, compared to the standard therapy of oxygen delivered by non-rebreathing facemask. Specific Aim 1 will provide toxicokinetic data to support a potential benefit in the use of CPAP for CO poisoning, by comparing CO elimination kinetics in response to oxygen therapy delivered by non-rebreathing facemask versus CPAP. The 20 patients expected in our first year will provide adequate power to detect a 20% fall in half-time of CO elimination. While CPAP may increase CO washout rates, as predicted in Specific Aim 1, demonstration of real functional benefit will be tested in Specific Aim 2. This Aim seeks to determine functional (neuropsychological) outcomes in patients with CO poisoning treated with oxygen therapy delivered by non-rebreathing facemask versus CPAP. Data showing a therapeutic benefit from CPAP in CO poisoning would have clinical implications. Compared to hyperbaric oxygen therapy, CPAP therapy can begin earlier, including the pre-hospital setting, for patients with known exposure. With the frequent nature of CO poisoning and the widespread availability of CPAP, a potential benefit could lead to improved outcomes for the 20,000+ patients who present to EDs annually.

Official Title
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Randomized Trial of Carbon Monoxide Elimination Kinetics With Oxygen Delivered by Continuous Positive Airway Pressure Compared to Face Mask

Conditions
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Carbon Monoxide Poisoning

Intervention / Treatment
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* Device: Continuous Positive Airway Pressure
* Device: Non-rebreather oxygen mask


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Elevated Carboxyhemoglobin Level (non-smokers >8%, smokers >12%) 18 years of age or older Able to provide informed consent as assessed by Attending Emergency Physician Exclusion Criteria: Requires daily medication for active lung disease Altered mental status Hemodynamically unstable Requires transfer to ICU or hyperbaric oxygen facility Previous enrollment in the study No concurrent acute psychiatric illness

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br>Participants in this arm are treated with Continuous Positive Airway Pressure at 5cm H2O and 100% oxygen | Device: Continuous Positive Airway Pressure<br>* Full face CPAP at 5cm H2O and 100% oxygen<br>|
| Active Comparator: 2<br>Participants in this arm receive standard of care therapy- oxygen via a non-rebreather mask | Device: Non-rebreather oxygen mask<br>* Oxygen administered through a non-rebreather mask<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Half life of Carboxyhemoglobin |  | Every 15 minutes during treatment | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Carbon Monoxide Toxicity, Carbon, Monoxide, Poisoning, Toxicity, Treatment, CPAP, Hyperbaric, Oxygen