The relationship between reduction of lung function and neural respiratory drive in healthy middle and aged subjects / 中华老年医学杂志

ABSTRACT

Objective To explore the relationship between reduction of lung function and neural respiratory drive in healthy middle and aged subjects. Methods Eight healthy middle and elderly subjects aged (57.3±5.0) years and 8 sex-matched healthy young subjects aged (28.3±3.4)years were enrolled iu this study. Conventional lung function tests were performed in all the subjects.Neural respiratory drive was assessed by electromyogram(EMG) recorded from a multipair esophageal electrode in quiescent condition and maximal forced inspiration. Results Maximal diaphragm EMG (EMGdi) at inspiration was similar between elderly and young subjects [(172.2 ± 54.66) μV vs.(175.0±55.7) μV,t -0.10,P=0.921] while vital capacity(VC) in the elderly subjects [(3.2±0.5)L] was much smaller than young subjects[(4.0±0.8)L](t=-2.27,P＜0.05).The tidal volume and ventilatory capacity per minute in quiescent condition in middle and aged people were similar to the youth,however,EMGdi％max was higher in the elderly subjects (27.8± 12.9)％ than in the young subjects (16.4±7.2)％ (t-2.18,P＜0.05).Effective drive of respiration center was much less in the elderly subjects than in young subjects [(62.7±23.2)％ vs.(128.6±96.2) ％].Conclusions Reserve of neural respiratory drive is less in the elderly than in young subjects.Decrease of lung function with ageing may be not due to reduction of neural respiratory drive but lung structure change.