Carbon Monoxide Poisoning
From Anvita Health Wiki
Contents |
Etiology
- toxic exposure from
- auto exhaust
- paint removers
- malfunctioning furnaces
- indoor grill
- smoke exposure
- age is predisposing factor to severity of injury
Epidemiology
- typical atmospheric concentration is 0.1 ppm
- OSHA standards for exposure set limit at 8 ppm for 8 hours
- 5-19% of patients presenting to emergency department with headache
Pathology
- inhalation of carbon monoxide
- formation of carboxyhemoglobin with reduction of oxygen- carrying capacity of blood
- affinity of hemoglobin for CO 250 X that of O2
- fatal levels > 70%; > 6% may cause cardiac ischemia in elderly patients with CAD
- cytochrome oxidase & possibly other cytochromes bind CO & possibly lead to direct cytotoxic effects
- CNS structural lesions
- bilateral necrosis of globus pallidus
- demyelination of cerebral white matter, including
- thalamic lesions
- hippocampal damage
- post- anoxic delayed encephalopathy
- 2 days to 7 weeks after exposure
- may be asymptomatic between exposure & onset of encephalopathy
Clinical-manifestations
-
- confusion, delirium
- difficulty concentrating
- difficulties with memory, short & long-term
- visuospatial deficits
- deficits in executive function
- muscular twitchings, convulsions
- affective disorder
- personality changes
- depression
- emotional lability8
- dilated pupils
- sleep disturbance
- stertorous (noisy, snoring) breathing
- parkinsonism
- cherry-red skin & mucosa
- hypertension
- bounding pulse
Laboratory
- blood grossly & abnormally red
- arterial blood gas for carboxyhemoglobin
- high carboxyhemoglobin levels indicate significant carbon monoxide exposure & tissue injury
- low levels do not rule out significant exposure or injury
- a carboxyhemoglobin > 25% is diagnostic of severe acute carbon monoxide poisoning
Diagnostic-procedures
- pulse oximetry is unreliable because pulse oximeters cannot distinguish carboxyhemoglobin from oxyhemoglobin
- electrocardiogram: evidence of myocardial ischemia
Radiology
- magnetic resonance imaging (not useful for acute exposure)
- tissue edema secondary to demyelination
Management
- oxygen (100%); Hgb:CO 1/2life of 27-246 minutes
- hyperbaric oxygen
-
- severe carbon monoxide poisoning
- loss of consciousness
- persistent neurologic deficits
- carboxyhemoglobin > 25-40%
- pregnancy
- evidence of cardiac ischemia:
- prevention
- inspect furnaces annually
- insure adequate ventilation
- internal combustion engines should not be operated in enclosed spaces without adequate venting
- indoor cooking with charcoal should not be done
- CO alarms (look for "UL" mark on product)
More General Terms
Additional Terms
References
- DeGowin & DeGowin's Diagnostic Examination, 6th edition, RL DeGowin (ed), McGraw Hill, NY 1994, pg 871
- Weaver LK. Critical Care Clinics 15(2):297, 1999
- Medical Knowledge Self Assessment Program (MKSAP) 15, American College of Physicians, Philadelphia 2009
- Carbon Monoxide Poisoning [1]
- National Guideline Clearinghouse Chemical inhalants/carbon monoxide inhalation. ngc-guideline: [2]
- Clinical policy: critical issues in the management of adult patients presenting to the emergency department with acute carbon monoxide poisoning. American College of Emergency Physicians ngc-guideline: [3]
