History and exam
Key diagnostic factors
common
exposure to incomplete combustion of carbon-containing material
A variety of sources generate CO, including internal combustion engines, water heaters, and home heating units. Kerosene space heaters were responsible for CO poisoning in the 1970s. Other sources of CO exposure are the paper mill industry, steel mills, explosives used in construction, petroleum refineries, and gasoline-or propane-powered machinery.[12][22][23]
exposure to fire with smoke inhalation
nausea
Nonspecific symptoms may occur.
headache
Nonspecific symptoms may occur.
vomiting
Nonspecific symptoms may occur.
blurred vision
Nonspecific symptoms may occur.
dizziness
Nonspecific symptoms may occur.
vertigo
Nonspecific symptoms may occur.
altered consciousness
Nonspecific symptoms, including drowsiness, tiredness, syncope, or confusion, may occur. Lethargy/mild tiredness can be a feature of chronic poisoning.[1] Coma may be present in people with severe poisoning.
dyspnea
Breathing difficulties or shortness of breath may occur.[1]
tachycardia
Nonspecific cardiovascular signs are a common feature.
hypotension or hypertension
Nonspecific cardiovascular signs are a common feature.
cardiac arrhythmias
Nonspecific cardiovascular signs are a common feature.
pain
Chest or abdominal pain may occur.
weakness
In one epidemiologic study, subjective weakness was reported in around 20% of patients with acute CO poisoning.[39]
sleep changes
Patient may be experiencing tiredness, fatigue, and sleep disturbance.[1]
irritability
May indicate severe poisoning.[27]
flu-like symptoms
A feature of chronic CO poisoning.[1]
Other diagnostic factors
common
exposure to methylene chloride
CO is formed during metabolism of methylene dichloride (dichloromethane). Exposure to CO during paint or furniture stripping and degreasing may result in poisoning.[25]
delayed neuropsychiatric features
May be present in a patient previously exposed to CO. Features include memory impairment, disorientation, apathy, mutism, irritability, inability to concentrate, emotional lability, peripheral neuropathy, incontinence, choreoathetosis, apraxia, psychosis, dementia, Parkinsonism, and hearing loss.[27][40][41]
other severe neurologic symptoms
cutaneous blistering
Nonspecific symptoms may occur.
pulmonary edema
Symptoms include shortness of breath.
uncommon
cardiac arrest
A feature of severe CO poisoning.
focal neurologic abnormalities (e.g., hemiplegia, truncal ataxia)
Neurologic symptoms include acute stroke-like symptoms. Truncal ataxia is a common physical sign in those who are conscious.
disseminated intravascular coagulation
May be a feature of CO poisoning.[42] See Disseminated intravascular coagulation.
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