Respiratory resistance from 1 to 46 ATA measured with the interrupter technique

Measurements of respiratory resistance by an interrupter technique were made in six subjects during a Navy saturation dive to 457 m. Repeated measurements were made at five depths with complete pulmonary function testing after the dive. Increase in resistance was about linear with gas density (rho). Three smokers exhibited a significantly steeper slope of the respiratory resistance versus rho relationship than three nonsmokers. The disparity in resistance among the divers became considerable only at great pressure. Likewise, the predictions of two contradictory fluid dynamic theories agreed fairly well with our data and with each other over the densities explored and disagreed greatly with our data only at higher pressures.