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.
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
- 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.
- 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.