carbon monoxide poisoning
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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 complaint of 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
- influenza-like symptoms, frontal headache,
- dizziness
- nausea/vomiting
- dyspnea
- chest pain
- cognitive deficits
- confusion, delirium
- difficulty concentrating
- difficulties with memory, short & long-term
- visuospatial deficits
- deficits in executive function
- disorder of arousal
- muscular twitchings, convulsions
- affective disorder
- personality changes
- depression
- emotional lability8
- dilated pupils
- sleep disturbance
- stertorous (noisy, snoring) breathing
- parkinsonism
- cherry-red skin & mucosa with development of cutaneous bullae after extensive exposure[6]
- hypertension
- bounding pulse
Laboratory
- blood grossly & abnormally red
- arterial blood gas with blood carboxyhemoglobin
- pulse oximetry not helpful[3]
- high carboxyhemoglobin in blood levels indicate significant carbon monoxide exposure & tissue injury
- low levels do not rule out significant exposure or injury
- a carboxyhemoglobin in blood > 25% is diagnostic of severe acute carbon monoxide poisoning
- complete blood count (CBC) leukocytosis
- serum troponin I may suggest myocardial ischemia
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
Complications
- myocardial ischemia occurs in 1/3 of patients[3]
- death
- up to 40% of patients develop delayed cognitive impairment days to months after recovery from acute effects of carbon monoxide poisoning[3]
Management
- oxygen (100%); Hgb:CO 1/2life of 27-246 minutes
- 100% oxygen by Venturi mask vs non-rebreathing mask at 15 L/min[3]
- FDA-approved device Clearmate for use in emergency room works by increasing rate of breathing[8]
- hyperbaric oxygen[3][4]
- may further diminish Hgb:CO 1/2life
- indicated for
- severe carbon monoxide poisoning
- loss of consciousness
- persistent neurologic deficits
- carboxyhemoglobin > 25-40%
- pregnancy
- evidence of cardiac ischemia:
- severe carbon monoxide poisoning
- may reduce risk of delayed cognitive impairment (see complications)[3]
- 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
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Medical Knowledge Self Assessment Program (MKSAP) 15, 16, 17, 18, 19. American College of Physicians, Philadelphia 2009, 2012, 2015, 2018, 2022.
Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022 - ↑ 4.0 4.1 Garrabou G, Inoriza JM, Moren C et al Hyperbaric oxygen therapy for carbon monoxide poisoning. Intensive Care Med. 2011 Oct;37(10):1711-2 PMID: https://www.ncbi.nlm.nih.gov/pubmed/21667143
- ↑ Hampson NB, Piantadosi CA, Thom SR, Weaver LK. Practice recommendations in the diagnosis, management, and prevention of carbon monoxide poisoning. Am J Respir Crit Care Med. 2012 Dec 1;186(11):1095-101. PMID: https://www.ncbi.nlm.nih.gov/pubmed/23087025
- ↑ 6.0 6.1 Harmon J, Kapitanyan R Poisoning Clues on the Skin: 10 Cases Medscape. April 6, 2017 http://reference.medscape.com/features/slideshow/acutepoisonings
- ↑ Centers for Disease Control & Prevention (CDC) Clinical Guidance for Carbon Monoxide (CO) Poisoning After a Disaster. https://www.cdc.gov/disasters/co_guidance.html
Hurricane Florence - Clinical Guidance For Carbon Monoxide (CO) Poisoning. CDC Health Alert Network. September 16, 2018 https://emergency.cdc.gov/han/han00415.asp - ↑ 8.0 8.1 FDA News Release. March 14, 2019 FDA allows marketing of new device to help treat carbon monoxide poisoning. https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm633533.htm