Condition category
Injury, Occupational Diseases, Poisoning
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status
Results overdue

Plain English Summary

Background and study aims:
Carbon monoxide (CO) is a leading cause of poisoning. There are 40,000 to 50,000 reported cases in the United States per year. It is assumed, however, that many more cases go unreported as it is difficult to diagnose. This is due to the nonspecific symptoms (for example, nausea, feeling tired and confused, vomiting, stomach pains and difficulty breathing) than can be similar to food poisoning or flu. CO poisoning not only leads to a number of acute symptoms but also to chronic complaints weeks or even months after the actual poisoning has taken place, the so called "neuropsychiatric sequelae". These symptoms can include headaches, nausea, lethargy, confusion, emotional lability, amnesia, and even psychosis. Current standard treatment of CO poisoning consists of inhaling oxygen via a simple face mask. The aim of this study is to test whether supporting the patients’ own breathing using a tight face mask and a ventilation machine (respirator) reduces the occurrence of those "neuropsychiatric sequelae".

Who can participate?
Patients treated for acute CO poisoning can be included in the study if the level of CO measured in their blood ("COHb") was at least 7% and they are at least 18 years old, not pregnant and that there was no need to insert a special tube to facilitate ventilation into their trachea ("intubation")

What does this study involve?
Patients are randomly assigned to either standard therapy (oxygen inhalation via a simple face mask) or study therapy (tight face mask and ventilation machine). During therapy CO-levels are continuously measured. Therapy will be stopped when CO-levels reach 3% or below. After completion of the therapy, a neuropsychiatric test will be performed. Patients will be contacted one month later to perform the test again, and will be asked about their quality of life.

What are the possible benefits and risks of participating?
All participants receive close monitoring and follow-up of their symptoms and quality of life.
If the study hypothesis proves to be true, patients in the intervention group (those that were treated with study therapy) receive a better treatment with the potential to reduce later complaints.
There are no anticipated risks from participation, however the face mask may feel uncomfortable for some patients.

Where is the study run from?
The study is run by the Department of Emergency Medicine of the Medical University of Vienna (Austria)

When is the study starting and how long is it expected to run for?
June 2014 to July 2015

Who is funding the study?
Austrian Association of Emergency and Disaster Medicine (Austria)

Who is the main contact?
Dr. Dominik Roth

Trial website

Contact information



Primary contact

Dr Dominik Roth


Contact details

Department of Emergency Medicine
Waehringer Guertel 18-20/6D

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Non-invasive CPAP-ventilation versus oxygen-therapy using a simple face mask for carbon monoxide poisoning: A single-center, randomised assessor-blinded controlled parallel-group study



Study hypothesis

Non-invasive CPAP ventilation using a tight face mask reduces the incidence of neuropsychological sequelae 1 month after carbon monoxide intoxication compared to standard oxygen inhalation using a simple face mask with oxygen reservoir.

Ethics approval

Medical University of Vienna Ethics Committee, 19/05/2011, ref. 251/2011

Study design

Single-center, randomised assessor-blinded controlled parallel-group study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Please use the contact details below to request a patient information sheet


Carbon monoxide poisoning


Intervention: Non-invasive CPAP ventilation using a tight mask and standard respirator equipment
Control: Oxygen inhalation therapy by a simple facemask with oxygen reservoir

Intervention type



Not Applicable

Drug names

Primary outcome measure

Absence of neuropsychological sequelae 1 month after intoxication

Secondary outcome measures

1. Time until COHb-level reaches 3% or less
2. Changes in neuropsychological sequelae between hospital discharge and 1 month after intoxication
3. Quality of life after 1 month
4. Mortality after 1 month
5. Adverse events
6. Length of Stay at ICU
7. Length of stay in hospital
8. Hospital admission within 1 month

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Adult patients (i.e. at least 18 years old) treated at the Emergency Department
2. Elevated levels of COHb (COHb >= 7%) AND either assured CO-exposition (for example, faulty gas-heater, fire) or symptoms consistent with CO poisoning

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Patients being comatose on admission
2. Patients intubated by Emergency Medical Service
3. Patients requiring mechanical ventilation
4. Pregnant women

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Department of Emergency Medicine

Sponsor information


Medical University of Vienna

Sponsor details

c/o Assoc. Prof. Dr. Christof Havel
Department of Emergency Medicine
Waehringer Guertel 18-20/6D

Sponsor type




Funder type

Research organisation

Funder name

Austrian Association of Emergency and Disaster Medicine: Reinhard Malzer scientific fund (Austria)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

02/09/2020: No publications found.