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Occult Carbon Monoxide Poisoning in ENT Practice: A Word of Caution
Author(s) -
Omar Ayoub,
N. B. Kenawy,
Huzefa Khalil
Publication year - 2003
Publication title -
the laryngoscope
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.181
H-Index - 148
eISSN - 1531-4995
pISSN - 0023-852X
DOI - 10.1097/00005537-200301000-00034
Subject(s) - carbon monoxide poisoning , occult , co poisoning , carbon monoxide , medicine , poison control , medical emergency , chemistry , pathology , alternative medicine , biochemistry , catalysis
Occult carbon dioxide (CO) poisoning can be defined as accidental poisoning in which the CO exposure is initially unknown to the patient and usually to the physician. Patients exposed to toxic levels of CO from fires and industrial accidents usually present no problem in diagnosis because the source of exposure is apparent. However, in patients exposed to CO from faulty furnaces, space heaters, and kitchen stoves, the diagnosis is frequently overlooked. This clinical problem first presented itself when a patient, referred to our outpatient department, who had a headache (sinus headache as the patient described it) had a complete ENT examination showing mild rhinitis; otherwise no obvious pathology was seen. Before that she had an eyesight test to exclude visual error, which showed no abnormality. The patient volunteered a piece of information, which was that they had a new gas heating system installed, the gas man did mention to them that the level of CO emitted from the old system was high although this was not documented, and this heating boiler was installed in the patient’s bedroom. The most common initial symptom of CO poisoning is headache, which may occur at blood carboxy hemoglobin (COHb) levels of 10% or greater. The problem is that the COHb half-life in room air is approximately 4 to 6 hours, and there are no characteristic physical signs to suggest occult CO poisoning. Flame-shaped retinal hemorrhages, previously described in patients exposed to toxic CO atmosphere for more than 12 hours, and Cheery red skin and mucous membranes are quite rare. Hypoxia to the cochlear nerve and brain may lead to a central hearing loss with a U-shaped audiogram; this has been demonstrated with the acute form of intoxication. Therefore, are we missing cases of chronic CO poisoning? This case has brought to our attention this probably overlooked class of headache, especially in cases in which an organic cause for headache could not be identified. The diagnosis of chronic or occult CO exposure requires an exact clinical history of cohabitants’ astute physical examination and especially high index of suspicion. The presence of COHb of 10% or higher, flame-shaped retinal hemorrhage, and U-shaped audiogram will certainly confirm the diagnosis.