Sun14November1246PM 16

Are the following true or false of carbon dioxide monitoring?

True / False

Mainstream analysers cause more delay than sidestream analysers Correct

End-tidal CO2 is 0.6-0.7 kPa higher than arterial partial pressure Correct

Carbon dioxide absorbs infrared radiation at 4.28 µm Correct

Is based on the principle of paramagnetism Correct

The mainstream analyser can only be used to measure a single gas Correct

Explanation

Capnography relies on the principle of infrared absorption. Carbon dioxide is made up of two dissimilar atoms and absorbs infrared radiation at a wavelength of 4.28 µm. End-tidal CO2 is normally 0.6-0.7 kPa lower than the arterial partial pressure.

Mainstream analyser is located within the patient's breathing system and therefore increases dead space but allows rapid analysis. The IRMATM mainstream probes (manufactured by the company Masimo) are comercially available. They can measure CO2, N2O and five volatile anaesthetic agents (halothane, enflurane, isoflurane, sevoflurane and desflurane).

Sidestream analyser consists of a small diameter tubing that samples gases at 150-200 mL/min. It can cause sampling delay but multiple gases and anaesthetic vapours can be analysed from the same sample.

Reference:

Al-Shaikh B, Stacey S. Essentials of Anaesthetic Equipment. 3rd ed. London: Churchill Livingstone; 2008.

Davis PD, Kenny GNC. Basic Physics and Measurement in Anaesthesia. 5th ed. Edinburgh: Butterworth Heinemann; 2009.

Answer Statistics

Not enough data to display the statistics

Average score: 70.00%

Times answered: 236