CO and oxyhemoglobin dissociation curve

Q:  Carbon monoxide (CO) moves oxyhemoglobin dissociation curve to - select one

A) left

B) right

Answer: A

Carbon monoxide is a colorless and odorless gas with an affinity for hemoglobin more than 200 times higher than oxygen. CO poisoning must be ruled out in all patients after inhalation injury or fires by documented blood carboxyhemoglobin level.

Pulse oximetry cannot rule out carbon monoxide poisoning. PulseOx does not differentiate carboxyhemoglobin from oxyhemoglobin. Carboxyhemoglobin levels should be measured with CO-oximetry, preferably on the arterial blood.

Carboxyhemoglobin shifts the oxyhemoglobin dissociation curve to the left, impairing the release of oxygen at the tissues and utilization of oxygen in mitochondria, causing tissue hypoxia.

#hematology

#toxicity

References:

1. Rehberg S, Maybauer MO, Enkhbaatar P, et al. Pathophysiology, management and treatment of smoke inhalation injury. Expert Rev Respir Med 2009; 3:283.

2. Prien T, Traber DL. Toxic smoke compounds and inhalation injury--a review. Burns Incl Therm Inj 1988; 14:451.

3. Blumenthal I. Carbon monoxide poisoning. J R Soc Med. 2001 Jun;94(6):270-2. doi: 10.1177/014107680109400604. PMID: 11387414; PMCID: PMC1281520.