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Carbon monoxide poisoning

Key sources
The following summarized guidelines for the evaluation and management of carbon monoxide poisoning are prepared by our editorial team based on guidelines from the Association of the Scientific Medical Societies in Germany (AWMF 2021), the American Heart Association (AHA 2020), the American College of Emergency Physicians (ACEP 2017), and the British Thoracic Society (BTS 2017).


1.Screening and diagnosis

Diagnosis: diagnose CO poisoning based on clinical symptoms and proven or probable exposure to CO.
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  • Differential diagnosis

2.Classification and risk stratification

Settings of exposure: recognize that CO can occur in numerous situations and ambient conditions, including:
fire smoke
loss of consciousness without apparent cause in enclosed spaces with fireplaces (such as heaters, stoves, fireplaces, barbecues)
attempted suicide - often with corresponding indicators (suicide note, taped-off rooms)
in silos with large quantities of wood pellets
engine exhaust (without catalytic converter)
hookah use

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  • Classification

3.Diagnostic investigations

History and physical examination
Determine the source of CO exposure, especially in patients with CO poisoning not being brought in by emergency medical services, in order to identify other poisoned persons and, if necessary, prevent further CO poisoning from as yet unknown sources.
Perform a neurological examination, including the mini-mental state examination, in patients with clinical symptoms.
Obtain further specific evaluation if there is sufficient suspicion of a relevant differential diagnosis.

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  • CO pulse oximetry

  • Blood gas analysis

  • Evaluation for cardiac injury

  • Toxicological screening

4.Respiratory support

Supplemental oxygen and ventilation
As per AWMF 2021 guidelines:
Initiate immediate administration of 100% oxygen or ventilation in patients with suspected CO poisoning. Initiate oxygen administration in the prehospital phase of care.
Administer oxygen immediately at the highest possible concentration with any of the following techniques, regardless of the oxygen saturation:
mask CPAP
demand valve
constant dosing (high-flow) via tight-fitting mask with reservoir bag
invasively using appropriate airway protection if protective reflexes are inadequate

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  • Hyperbaric oxygen therapy

5.Medical management

Prehospital care: instruct first responders by the emergency dispatch center to observe measures of self-protection if signs of a potential hazard involving CO are detected and relay the information to the emergency medical services team.
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  • Indications for hospital admission

6.Inpatient care

Serial clinical assessment
Obtain clinical monitoring in accordance with the disease severity as long as patients are symptomatic.
Recognize that clinical symptoms do not correlate with COHb clearance from the blood. Do not obtain COHb monitoring alone for treatment management.

7.Patient education

Pre-discharge counseling: educate all patients with CO poisoning about the risk of delayed neurologic sequelae, symptoms, and time of onset. Instruct patients to present to a neurologist if delayed neurologic sequelae are suspected.

8.Preventative measures

Carbon monoxide detectors
Ensure the use of early-warning detectors (smoke and CO alarms) in every household.
Use a multi-stage approach depending on the concentration indicated when CO warning devices are used by emergency services.

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  • Alerting fire department

9.Follow-up and surveillance

Indications for neurologist referral: refer patients with suspected delayed neurologic sequelae to a neurologist.

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  • Indications for discharge

  • Cardiac surveillance