Effects of intrathoracic pressure, inhalation time, and breath hold time on lung diffusing capacity

• Published in: Respiratory physiology & neurobiology 2018-12, Vol.258, p.69-75
• Main Authors: Jorgenson, Caitlin C., Coffman, Kirsten E., Johnson, Bruce D.
• Format: Article
• Language: English
• Subjects: Alveolar-capillary membrane conductance; Pulmonary capillary blood volume; Single breath hold maneuver; Submaximal exercise
• ISSN: 1569-9048; 1878-1519
• DOI: 10.1016/j.resp.2018.06.001

•We measure DLCO and DLNO using the single breath hold technique.•We evaluate the effects of changing intrathoracic pressure, inhalation time, and breath hold time on DLCO, DmCO and Vc.•DLCO and Vc increase with exercise regardless of changes in intrathoracic pressure, inhalation time, and breath hold time.•DmCO does not increase from rest to submaximal exercise using the finite θNO assumption. The single breath hold maneuver for measuring lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO) incorporates multiple sources of variability. This study examined how changes in intrathoracic pressure, inhalation time, and breath hold time affect DLCO, DLNO, alveolar-capillary membrane conductance (DmCO) and pulmonary capillary blood volume (Vc) at rest and during submaximal exercise. Thirteen healthy subjects (mean ± SD; age = 26 ± 3y) performed duplicate tests at rest and during submaximal exercise. DLCO and Vc were lower with a positive versus negative intrathoracic pressure during the breath hold at rest (DLCO: 22.2 ± 5.5 vs. 22.7 ± 5.5 ml/min/mmHg, p = 0.028; Vc: 46.5 ± 11.6 vs. 48.2 ± 11.7 ml, p = 0.018). However, during exercise, DLCO and Vc were higher with positive versus negative pressure (DLCO: 26.7 ± 5.5 vs. 25.7 ± 5.7 ml/min/mmHg, p = 0.014; Vc: 56.2 ± 12.6 vs. 53.9 ± 13.1 ml, p = 0.039). The inhalation time did not significantly affect DLCO, DLNO, DmCO or Vc. Short breath hold times (