In asthma, lower end-tidal carbon dioxide may predict acute exacerbation outcomes, although other measures may be better severity indicators.

Does end tidal CO2 monitoring during emergency department ... However, hypoxia was significantly more common in the group without capnography readings (42% vs 25%, 95% CI 1.3–33% p=0.035).

Porte, P. (2007). Predicting diabetic ketoacidosis in children by measuring end-tidal CO2 via non-invasive nasal capnography. Journal of Paediatrics and Child Health, 43(), 677–680. doi ...

The diagnostic role of capnography in pulmonary embolism. Am J Emerg Med 2010, May, 28(4):460-5 Raheem MS, Wahba OM. A nasal catheter for measurement of end-tidal carbon dioxide in spontaneously ...