Chest flow during the initial inspiratory phase (V0.1) in pulmonary diseased patients
Mishima, M.; Kawakami, K.; Sakai, N.; Hirai, T.; Fukui, M.; Oku, Y.; Chin, K.; Ohi, M.; Kuno, K.
Frontiers of Medical and Biological Engineering the International Journal of the Japan Society of Medical Electronics and Biological Engineering 7(3): 177-188
1996
ISSN/ISBN: 0921-3775 PMID: 8882904 Document Number: 462915
We measured the chest flow 0.1 s after the onset of the inspiratory phase ( ovrhdot V-0.1) in patients with chronic pulmonary emphysema (CPE: n = 5), interstitial pneumonitis (IP: n = 5) and normal subjects (Nor: n = 5). The subjects sat in a body box and breathed air from outside of the body box. ovrhdot V-0.1 was measured during rest and during maximal breathing ( ovrhdot V-0.1-max) and then these results were compared with P-0.1 (P-0.1-rest, P-0.1-max) values. ovrhdot V-0.1-rest was not significantly different between the three groups (Nor: 0.25 +- 0.10, CPE: 0.27 +- 0.06, IP: 0.26 +- 0.06 l/s), whereas the P-0.1-rest in IP patients was significantly greater than in normal subjects (Nor: 1.98 +- 0.61, CPE: 3.00 +- 0.80, IP: 3.60 +- 0.68* hPa; *P lt 0.05 compared with normal). The ovrhdot V-0.1-max in CPE and IP patients was significantly lower than in normal subjects (Nor: 3.66 +- 1.16, CPE: 0.82 +- 0.25*, IP: 1.02 +- 0.21* l/s, *P lt 0.05 compared with normal), whereas P-0.1-max in IP patients was not significantly different with in normal subjects (Nor: 33.2 +- 10.2, CPE: 9.8 +- 3.7*, IP: 19.5 +- 3.4** hPa, *P lt 0.05 compared with normal, **P lt 0.05 compared with CPE). A simulation of the influence of the mechanical properties of the respiratory system on ovrhdot V-0.1 and P-0.1 using the Runge-Kutta method suggested that ovrhdot V-0.1 was negatively affected by airway resistance but positively affected by chest wall and lung compliance. In contrast, the influence of respiratory mechanics on P-0.1 was much less than on the ovrhdot V-0.1, except for highly decreased lung compliance. In CPE patients, it was suspected that mechanical disorders might not simply be the determining factors of ovrhdot V-0.1-max, but that limitations of the neuro-muscular drive due to chest wall deformity may also play a definitive role in the smaller ovrhdot V-0.1-max. In contrast, it may be inferred that IP patients had to exert greater inspiratory effort as compared with the other two groups in order to maintain a similar ovrhdot V-0.1-rest because of the increased airway resistance and decreased tissue compliance; thus these abnormal mechanical properties suppress the increase in the ovrhdot V-0.1-max. It may be concluded that ovrhdot V-0.1 is a good index of chest wall acceleration, which is determined by both the neuro-muscular drive and the mechanics of the respiratory system.