To elucidate the mechanics of pursed-lip breathing (PLB), which is a traditional skill to alleviate dyspnea, especially in patients with severe airflow limitation such as chronic obstructive pulmonary disease (COPD).
Twenty healthy volunteers were studied. Of these, in 10 subjects (7 women and 3 men), aged 26 to 48 years (39.2 ± 7.3 years; mean ± SD), total respiratory system impedance (Zrs) was measured, and the other 10, aged 29 to 77 years (55.0 ± 14.9 years), were examined for nasopharyngeal phenomena endoscopically. Informed consent was obtained from all the volunteers. Zrs during PLB with or without a noseclip was measured using the forced oscillation technique at 3 Hz. Zrs was measured through a mouthpiece during quiet normal breathing or through a facemask during PLB. To confirm the nasopharyngeal function during PLB, endoscopic observation was performed.
Under the condition of wearing a noseclip, PLB significantly increased the Zrs from 0.37 ± 0.15 to 0.87 ± 0.34 (kPa/L/min; mean ± SD). PLB also increased Zrs without a noseclip, showing similar results as those with a noseclip. The nasopharynx was widely opened during normal breathing. However, immediately after the start of PLB, the pharyngeal cavity was completely and strongly closed. This nasopharyngeal movement could consistently be observed in all the subjects.
These results demonstrated 1) the extent of the oral resistance, and 2) the nasopharyngeal closure, during PLB.
A noseclip is not necessary during PLB. Estimation of respiratory impedance during PLB would be helpful to estimate the dilating force on the small airways.
Yuko Sano, None.