eMedicine Specialties > Emergency Medicine > Toxicology

Toxicity, Carbon Monoxide: Follow-up

Author: Guy N Shochat, MD, Associate Clinical Professor of Emergency Medicine, University of California at San Francisco
Coauthor(s): Michael Lucchesi, MD, Chair, Associate Professor, Department of Emergency Medicine, State University of New York at Brooklyn
Contributor Information and Disclosures

Updated: Feb 17, 2009

Follow-up

Further Inpatient Care

  • Admitted patients generally require monitored settings, telemetry beds, or cardiac care unit/medical intensive care unit (CCU/MICU) beds for more severe cases.
  • Patients with cerebral edema may be most appropriately treated in a neurosurgical ICU setting; this may dictate transfer to another facility. Admission or consult by toxicology service is helpful in these cases.

Further Outpatient Care

  • Asymptomatic patients with HbCO levels below 10% may be discharged.
  • Arrange early follow-up care with a medical toxicologist or hyperbaricist experienced in CO poisoning.

Prognosis

  • Variability of clinical severity, laboratory values, and outcome limits prognostic accuracy.
  • Cardiac arrest, coma, metabolic acidosis, and high HbCO levels are associated with poor outcome.
  • Abnormal findings on CT scan are associated with persistent neurologic impairment.
  • Neuropsychiatric testing may have prognostic efficacy in determining delayed sequelae.

Patient Education

  • Discuss the possibility of delayed neurologic complications, although they are much more common in admitted patients.
  • Suggest minimizing physical activity for 2-4 weeks.
  • Advise patient to stop smoking.
  • For excellent patient education resources, visit eMedicine's Poisoning Center. Also, see eMedicine's patient education article Carbon Monoxide Poisoning.

Miscellaneous

Medicolegal Pitfalls

  • Failure to accurately diagnose is the principle concern. A level of clinical aggression is necessary in patients with cardiovascular disease and pregnant patients. Explaining the possibility of delayed neurologic sequelae is important.
  • Failure to provide 100% oxygen (via a nonrebreather mask) while awaiting for carboxyhemoglobin levels
  • Failure to transfer a person with moderate intoxication to a HBO facility may be of more concern if continued research validates such use.
  • Failure to contact all parties who still may be at risk from exposure could allow for further CO toxicity.
  • Failure to address co-ingestions in the case of suicide attempt
  • Failure to diagnose pregnancy in exposed patient
  • Failure to identify CO exposure in coworkers or the patient's family
  • Failure to contact the fire department for the assessment of environmental exposure, CO source identification, and decontamination (eg, home furnace, malfunctioning propane propelled equipment)

Special Concerns

  • Fetomaternal poisoning
    • A pregnant CO-poisoned patient represents a particular quandary. Although the mother may appear well with seemingly nontoxic levels, the developing fetus is at increased risk. Additionally, new research suggests a correlation between pre-term labor in the third trimester and CO exposure.
    • With a relatively small amount of scientific data support, conservative thought dictates treatment for any pregnant patient with evidence of CO exposure. CO displaces the oxygen-hemoglobin dissociation curve to the left. Fetal oxyhemoglobin dissociation curve lies further to the left than normal adult hemoglobin.
    • In the pregnant patient, a significant lag time exists for uptake and elimination of CO between the mother and fetus.
    • Fetal HbCO levels indicate little change during the first hour of maternal intoxication, yet they increase slowly over the first 24 hours. The peak actually may exceed maternal HbCO levels.
    • The fetus is particularly vulnerable with increased accumulation in fetal blood 10-15% higher than maternal blood and lower PaO2 levels (20-30 mm Hg compared with 100 mm Hg in adults). It is important to realize that acute nonlethal maternal intoxication may result in fetal demise. After intoxication, during the washout phase at room air temperature, fetal HbCO half-life is 7-9 hours.
    • Fetal HbCO half-life with pure hyperbaric oxygen treatment is not accurately known; however, with maternal normobaric oxygen therapy, the fetal HbCO half-life can be reduced to 3-4 hours.
    • Because fetal hemoglobin constitutes 20­-30% of the total at 3 months, neonates are at particularly greater risk than their infant and toddler counterparts.
  • Carbon monoxide (CO) detectors: Home CO detectors with audible alarms are available. One study of 911 calls for suspected CO poisoning showed that 80% of calls for alarming detectors resulted in verifiable ambient CO levels; the mean concentration of CO was 18.6 ppm in homes tested for alarming detectors but was 96.6 ppm in those homes tested following calls for suspicious symptomatology.
  • COPD: Clinician must remain aware of the potential for suppression of the respiratory drive in a chronically hypoxic patient. This should not result in the withholding of oxygen therapy in the already compromised patient.8
 


More on Toxicity, Carbon Monoxide

Overview: Toxicity, Carbon Monoxide
Differential Diagnoses & Workup: Toxicity, Carbon Monoxide
Treatment & Medication: Toxicity, Carbon Monoxide
Follow-up: Toxicity, Carbon Monoxide
Multimedia: Toxicity, Carbon Monoxide
References
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Further Reading

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Keywords

carbon monoxide toxicity, carbon monoxide poisoning, carbon monoxide exposure, CO exposure, CO poisoning, CO toxicity, CO intoxication, carbon monoxide intoxication, acute CO intoxication

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Contributor Information and Disclosures

Author

Guy N Shochat, MD, Associate Clinical Professor of Emergency Medicine, University of California at San Francisco
Guy N Shochat, MD is a member of the following medical societies: Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Michael Lucchesi, MD, Chair, Associate Professor, Department of Emergency Medicine, State University of New York at Brooklyn
Michael Lucchesi, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Peter MC DeBlieux, MD, Professor of Clinical Medicine and Pediatrics, Section of Pulmonary and Critical Care Medicine, Program Director, Department of Emergency Medicine, Louisiana State University Health Sciences Center
Peter MC DeBlieux, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, Radiological Society of North America, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

John T VanDeVoort, PharmD, Regional Director of Pharmacy, Sacred Heart & St. Joseph's Hospitals
John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists
Disclosure: Nothing to disclose.

Managing Editor

John G Benitez, MD, MPH, FACMT, FACPM, FAAEM, Associate Professor, Department of Medicine, Clinical Pharmacology Division, Vanderbilt University; Managing Director, Tennessee Poison Center
John G Benitez, MD, MPH, FACMT, FACPM, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, American College of Medical Toxicology, American College of Preventive Medicine, Society for Academic Emergency Medicine, Undersea and Hyperbaric Medical Society, and Wilderness Medical Society
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Asim Tarabar, MD, Assistant Professor, Department of Surgery, Section of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital
Disclosure: Nothing to disclose.

 
 
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