Capnography waves

Keyword

capnography, capnogram

A : normal in controlled mechanical ventilation

B : normal during spontaneous breathing

C : bronchospasm (asthma, COPD) / partially obstructed ET tube or breathing circuit

D : cardiogenic oscillation at the end of exhalation as flow decreases and the beating heart

causes emptying the different lung regions and back-and-forth motion between exhaled and fresh gas

E : spontaneous breathing effort during controlled mechanical ventilation

F : esophageal intubation

G : rebreathing of CO2, as may occur with faulty expiratory valve or exhausted absorber system

H : faulty inspiratory valve

I : single lung transplant

J : faulty inspiratory valve

K : abrupt onset of a ruptured or leaking ET tube cuff

L : leak in a sidestream sample line

Reference

Miller’s Anesthesia, 8th edition, Ch.51, P.1554