[Reference values for inspiratory capacity in healthy nonsmokers over age 50 years].
OBJECTIVE
The role of dynamic hyperinflation in triggering dyspnea and limiting exercise capacity in patients with chronic obstructive pulmonary disease has been recognized in recent years. The degree of dynamic hyperinflation can be assessed by measuring reduction in inspiratory capacity (IC). The aim of this study was to establish reference values for IC in healthy individuals of both sexes between the ages of 50 and 87 years, as such data are scarce in the literature.


METHODS
We studied 155 healthy volunteers (93 women) with normal spirometry. None had a prior history of respiratory, cardiovascular, or systemic diseases that might alter lung function. All were never-smokers. IC was measured during a normal, unforced inspiration to total lung capacity starting from functional residual capacity. The highest value of 6 satisfactory maneuvers was recorded. Sex, height, age, and weight were included in the regression equations. One thousand bootstrap samples for each sex were also analyzed.


RESULTS
For each sex, we found that a model including age, height, and weight produced IC prediction equations with a coefficient of determination (r2) of 0.414 for women and 0.447 for men. The mean (SD) intrasubject coefficient of variation was 4.3% (2%) for IC measured during a single session and 5.1% (0.4%) for measurements from 5 weekly sessions.


CONCLUSIONS
Our results provide reference equations for IC that are valid for a healthy population over 50 years of age. Predicted values were similar to those recently obtained in an Italian population aged between 65 and 85 years.
Lisboa
Carmen
C
Departamento de Enfermedades Respiratorias, Facultad de Medicina y Escuela de Psicología, Pontificia Universidad Católica de Chile, Santiago, Chile. clisboa@med.puc.cl
Leiva
Alicia
A
Pinochet
Ramón
R
Repetto
Paula
P
Borzone
Gisella
G
Díaz
Orlando
O
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007320:Inspiratory Capacity / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012016:Reference Values