Figure 1.
Graphical representative of the change in breath-by-breath end tidal C2H2/He following a single inhalation of 0.9% C2H2, 9% He for a single subject. Following inhalation C2H2/He falls as C2H2 is distributed in the pulmonary blood volume. At the point when a significant volume of C2H2 is returned to the right side of the heart and re-enters the pulmonary circulation, C2H2/He will start to rise. The time taken from inhalation (time 0) until where C2H2/He shows a significant rise and consistent rise was calculated as being the circulation time.
