2006 OPEN FORUM Abstracts
UNSUSPECTED CARBON MONOXIDE TOXICITY DETECTED BY NON-INVASIVE MONITORING: A CASE REPORT
Robert Partridge, MD, MPH, Kerlen J Chee, MD, Selim Suner, MD,
Andrew Sucov, MD, Gregory D. Jay, MD, PhD. Department of Emergency Medicine,
Rhode Island Hospital, Brown Medical School, Providence, RI.
Introduction: Carbon monoxide (CO)
poisoning is the most common cause of poisoning in the United States.
Approximately 15,200 patients were treated for suspected or confirmed non-fire
related unintentional CO exposure annually in emergency departments (EDs) in
the United States from 2001-2003. In the same period approximately 480 people
succumbed to CO poisoning from unsuspected CO exposure. Since adopting
Co-oximetry as part of the standard triage process in a high volume (>95,000
annual adult census), urban ED, we have identified 9 cases of unsuspected CO
poisoning over a 5-month period. A case report of one of these patients
follows:
Case: A 52 year old previously
healthy non-smoking female patient was brought to the ED by ambulance. The
patient complained of headache, nausea, dizziness and feeling cold. She
described to the triage nurses that she was emotionally upset because her
electric utilities were terminated and she had an argument with her son. She
denied syncope or chest pain, and offered no history of CO exposure. The
patient's vital signs included a temperature of 96.8 F, heart rate 103, blood
pressure 139/88mm/Hg, respiratory rate 16, and pulse oximetry 95% on ambient
air. At the same time that her vital signs were taken, a SpCO was obtained
using a non-invasive spectral analysis Co-oximeter. The level recorded was 33%,
later confirmed with a venous carboxyhemoglobin of 36%. Her physical
examination was within normal limits. The patient was placed immediately on
high flow oxygen with a non-rebreather mask. Her SpCO was monitored during
treatment and after 120 minutes had fallen to 9%, with complete resolution of
her symptoms. Further questioning of this patient revealed that after her
electric utilities were interrupted she began using an outdoor use gas-powered
electric generator in her basement. The local fire department was contacted and
a home investigation initiated. No other persons were found in the home.
Discussion: Carbon monoxide is a
colorless, odorless gas that is a product of combustion. The symptoms of early
CO toxicity are non-specific, and include headache, nausea, vomiting, diarrhea
and weakness. CO toxicity can rapidly progress to cardiac ischemia, confusion,
seizures, coma and death if a person is not removed from the source of
exposure. Because early CO toxicity shares similarities with other more common
illnesses, physicians must maintain a high index of suspicion for CO poisoning
to avoid incorrect diagnosis, management and disposition. Unrecognized CO
poisoned patients returned to the site of exposure may develop more serious CO
toxicity. Many patients are unaware that they were exposed to CO and may not
provide the clinician with sufficient history to prompt sending a venous
carboxyhemoglobin level. As a result, the prevalence of CO exposure and
poisoning in the general population is unknown and many cases may go
unrecognized. Fires, certain work
environments, mass casualty and disaster situations are all known to be
associated with CO poisoning. Venous carboxyhemoglobin analysis, the current
gold standard, is invasive, time-consuming, and costly. Routine screening of
large numbers of patients using this method is not cost effective or practical.
The use of non-invasive spectral analysis Co-oximetry is a rapid, inexpensive
method for screening large numbers of patients for CO toxicity and identifying
unsuspected cases that might otherwise be missed.