Image Based Question-65895

A 40 year old charcoal burner worker is brought to the emergency room with lightheadedness, confusion and headache with discoloration of skin as shown in the picture below, due to an inhalational poisoning. What will be expected in the blood ABG?

A. PO2 normal, O2 saturation less .

B. PO2 less, O2 saturation normal.

C. PO2 high, O2 saturation normal.

D. PO2 less, O 2 saturation decreased.

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Correct Answer » A Explanation

Ans:A. PO2 normal, O2 saturation less .

The patient is suffering from carbon monoxide poisoning from the history and Bright cherry red discolouration of skin seen.

Carbon Monoxide Poisoning

• Carbon monoxide (CO) is a colourless, odourless gas produced by incomplete combustion of carbonaceous material

• CO poisoning may be acute or chronic

• Exposure is most commonly from suicide attempts using car exhaust, and accidental exposures from incomplete combustion in charcoal burners, faulty heaters, fires, and industrial accidents

Pathophysiology:

• Carbon monoxide has 210 times the affinity for haemoglobin than oxygen.

• So,in ABG,O2 saturation is less.

• HbCO (elevated levels are significant, but low levels do not rule out exposure)

• PO2 is normal since dissolved O2 is normal..

• Binding therefore renders haemoglobin oxygen carrying capacity and delivery to the tissues. This can result in tissue hypoxia and ischaemic injury.

• Form of Hypoxia produced is anemic hypoxia.

• Oxygen dissociation curve shifts to left.

• Metabolic acidosis may occur

• The cherry red skin colour produced when carboxyhaemoglobin (COHb) concentrations exceed about 20% is rarely seen.

• CO also binds to intracellular cytochromes, impairing aerobic metabolism.

• Carbon monoxide also triggers endothelial oxidative injury, lipid peroxidation and an inflammatory cascade.

• These mechanisms are probably responsible for delayed neurological sequelae.

Symptoms :

• Mild acute poisoning include lightheadedness, confusion, headache, feeling like the world is spinning, and flu-like effects.

• Larger exposures can lead to toxicity of the central nervous system and heart, and death.