Carbon monoxide Poisoning...

Two patients are brought in from the same flat, unconscious with suspected carbon monoxide poisoning.
Which of the following is true concerning the symptoms, signs and management of carbon monoxide poisoning?
A. Pre-existing arteriosclerosis does not increase mortality
B. Carboxyhaemoglobin concentrations are always below 5% in healthy patients
C. Pregnancy is a contraindication to hyperbaric oxygen therapy
D. Cerebellar signs are the most reliable sign of neurological toxicity
E. Sodium bicarbonate is useful in correcting minor metabolic acidosis


Answer:
D--Cerebellar signs are the most reliable sign of neurological toxicity

Discussion: Carbon monoxide is the commonest cause of poisoning associated death in the United
Kingdom.

Patients with pre-existing vascular disease are at an increased risk of morbidity and
mortality from carbon monoxide poisoning.

Carboxyhaemoglobin concentrations are typically below 5% in healthy patients, but may be as high as 10% in heavy smokers.

 Cerebellar signs are the most reliable sign of significant neurological toxicity.

Tretament consists of removing the patient from the source of the carbon monoxide, giving high-flow oxygen (12 l/min) via a tight-fitting mask without a rebreathing circuit and consideration of hyperbaric oxygen therapy.
Indications for this include

• any history of unconsciousness, 
• carboxyhaemoglobin concentrations over 40% at any time, 
• pregnancy,
• documented neurological signs and 
• ECG changes.

There are some relative contraindications:
Patients with arrhythmias that may require cardioversion, since this is not possible within the hyperbaric chamber; and Patients with asthma or COPD due to the increased risk of pneumothorax. Although sodium bicarbonate can correct any metabolic acidosis, it can also decrease oxygen release to the tissues.