The basic principle of the OpCO is that a very precise volume of carbon monoxide (CO) is inhaled and re-breath by the patient. Then, based on the resulting increase in CO bound to haemoglobin the mass of haemoglobin is calculated.

 

With the OpCO the CO gas is re-breath for 10 min (shorter and longer periods are possible) as this will allow for an optimal uptake and distribution of CO throughout the circulation.

 

During the re-breathing period 100% O2 is administrated to the patient on a demand basis which allows for an easy and effortless measurement.

 

Due to the small volume of CO administrated and the continous O2 supplementation arterial O2 content is barely affected.