title: Methods for Measuring Lung Volumes: Is There a Better One?
abstract: BACKGROUND
  Accurate measurement of lung volumes is of paramount importance to establish the presence of ventilatory defects and give insights for diagnostic and/or therapeutic purposes.
  
  
  OBJECTIVE
  It was the aim of this study to measure lung volumes in subjects with respiratory disorders and in normal controls by 3 different techniques (plethysmographic, dilutional and radiographic methods), in an attempt to clarify the role of each of them in performing such a task, without any presumptive 'a priori' superiority of one method above others. Patients andMethods: In different groups of subjects with obstructive and restrictive ventilatory defects and in a normal control group, total lung capacity, functional residual capacity (FRC) and residual volume were measured by body plethysmography, multi-breath helium (He) dilution and radiographic CT scan method with spirometric gating.
  
  
  RESULTS
  The 3 methods gave comparable results in normal subjects and in patients with a restrictive defect. In patients with an obstructive defect, CT scan and plethysmography showed similar lung volumes, while on average significantly lower lung volumes were obtained with the He dilution technique. Taking into account that the He dilution technique does primarily measure FRC during tidal breathing, our data suggest that in some patients with an obstructive defect, a number of small airways can be functionally closed at end-expiratory lung volume, preventing He to reach the lung regions subserved by these airways.
  
  
  CONCLUSIONS
  In all circumstances, both CT scan with spirometric gating and plethysmographic methods provide similar values of lung volumes. In contrast, the He dilution method can measure lower lung volumes in some patients with chronic airflow obstruction.
authors.affiliation: Respiratory Medicine Unit, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Tantucci
authors.forename: Damiano
authors.initials: D
authors.lastname: Bottone
authors.forename: Andrea
authors.initials: A
authors.lastname: Borghesi
authors.forename: Michele
authors.initials: M
authors.lastname: Guerini
authors.forename: Federico
authors.initials: F
authors.lastname: Quadri
authors.forename: Laura
authors.initials: L
authors.lastname: Pini
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D005260:Female; D005652:Functional Residual Capacity; D006371:Helium; D006801:Humans; D007201:Indicator Dilution Techniques; D008168:Lung / Q000000981:diagnostic imaging* / Q000502:physiology / Q000503:physiopathology; D008171:Lung Diseases / Q000503:physiopathology*; D008176:Lung Volume Measurements / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010991:Plethysmography; D012115:Residual Volume; D013147:Spirometry; D014057:Tomography, X-Ray Computed; D014109:Total Lung Capacity
chemical_list: D006371:Helium