Carbon monoxide poisoning

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

all patients

1st line – supportive care and monitoring

Plus – supplemental oxygen therapy

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Plus –

supplemental oxygen therapy

Treatment recommended for ALL patients in selected patient group

Supplemental 100% oxygen therapy should be initiated as soon as the diagnosis is considered, and should not be discontinued until the diagnosis is ruled-out.

Therapy is started with a non-rebreather oxygen mask or high-flow nasal cannula regardless of CO-oximetry readings or SaO ₂ levels, while the patient is evaluated for possible hyperbaric oxygen therapy at the earliest opportunity.[55] Clinical presentation, symptoms, and blood gas CO-Hb levels should decide the duration of treatment. Conventional pulse oximetry does not differentiate the oxyhemoglobin and CO-Hb complex and should not be used as a measure of oxygen saturation in patients with CO poisoning.[4][27] Laboratory blood gas CO-oximetry (drawn from venous or arterial blood) should be used; noninvasive CO-oximetry should only be used as a general screening tool as it is not accurate enough to either rule in or rule out CO poisoning in a patient with suspected CO poisoning.[30][32]

Administering 100% oxygen reduces the half life of carbon monoxide to 85 minutes compared to 4-5 hours in standard room air conditions.[30] This can be further reduced to around 20 minutes with hyperbaric oxygen.[30]

Consider – hyperbaric oxygen therapy

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Consider –

hyperbaric oxygen therapy

Treatment recommended for SOME patients in selected patient group

Should be considered in patients with the following: loss of consciousness, ischemic cardiac changes, neurologic deficits, significant metabolic acidosis, and or peak CO-Hb levels ≥25%.[4][27][56][57][58][59] The American College of Emergency Physicians (ACEP) recommends that emergency physicians use either hyperbaric oxygen therapy or high-flow normobaric therapy for acute CO poisoning.

The ACEP acknowledges that there is no clear evidence that one approach is more effective than the other in terms of preventing delayed neurocognitive sequelae. The ACEP’s recommendation is intended to support physicians who choose not to refer patients for hyperbaric oxygen therapy, owing to, for example, time or geographic constraints.[30] One systematic review of six clinical trials found no significant benefit to hyperbaric oxygen therapy in preventing delayed neurocognitive deficits.[60] A key limitation of this analysis was the heterogeneity in the trials on primary outcome, the dosage and number of hyperbaric oxygen therapy sessions, and delays to therapy. Negative clinical trials have typically used a clinically ineffective dose of hyperbaric oxygen.[59] The only included randomized controlled trial (RCT) that met all Consolidated Standards of Reporting Trials (CONSORT) criteria for assessing quality of RCTs showed a significant benefit from hyperbaric oxygen.[57] The study used the following protocol:

First session: 3.0 atmospheres for 60 minutes, followed by 2.0 atmospheres for 60 minutes
Second and third sessions: 2.0 atmospheres for 120 minutes.

One subsequent consensus opinion recommended the use of this trial to guide clinical practice until further information from future studies becomes available.[2][4][56][58]

If hyperbaric oxygen is required, some centers recommend that it should be started within six hours and no later than 24 hours.[40]

For nonintubated patients, hyperbaric treatments are recommended until signs and symptoms have resolved, or until a clinical plateau has been reached (usually a maximum of three treatments).[59] For intubated patients whose neurologic exam must be abbreviated out of necessity, three treatments are recommended.[61]

Consider – intravenous insulin (and monitoring of blood glucose)

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Consider –

intravenous insulin (and monitoring of blood glucose)

Treatment recommended for SOME patients in selected patient group

Hyperglycemia can occur after various types of severe brain injury, regardless of preexisting diabetes mellitus.[62][63][64] There is evidence that neurologic outcomes are worse in patients with hyperglycemia, although evidence specific to CO poisoning is limited.[33][65][66][67] Treating hyperglycemia with insulin is therefore appropriate. It is critical, however, to avoid dangerously low levels of blood glucose through over-aggressive treatment of hyperglycemia.[68]

Primary options

insulin regular: see local protocol for administration guidelines

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Carbon monoxide poisoning

all patients

supportive care and monitoring

supplemental oxygen therapy

hyperbaric oxygen therapy

intravenous insulin (and monitoring of blood glucose)

Primary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

Carbon monoxide poisoning

Treatment algorithm

all patients

supportive care and monitoring

supplemental oxygen therapy

hyperbaric oxygen therapy

intravenous insulin (and monitoring of blood glucose)

Primary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options