PMID: 3180901Nov 1, 1988

Sources of error in flow-volume curves. Effect of expired volume measured at the mouth vs that measured in a body plethysmograph

A L CoatesP H Beaudry


The popularity of the maximum expiratory flow-volume curve (FVC) is in part due to the effort independence of expiratory flow. Of interest are expiratory flow rates at specific lung volumes, usually 50 and 25 percent of vital capacity (VC); Vmax50 and Vmax25, which make accurate assessment of lung volumes essential. Changes in lung volume during the test are due to both the volume of gas expired and the volume change due to gas compression (Vcomp). In normal subjects, Vcomp is small but may be considerable in those with airflow obstruction. When the FVC is measured in a plethysmograph (FVCp), both expired volume and Vcomp are measured. When the volume of the FVC is derived from gas expired at the mouth (FVCm), Vcomp is not considered and differences in Vmax25 or Vmax50 may occur. The magnitude of these errors was assessed in 30 children and young adults: nine normal subjects, ten with cystic fibrosis (CF) and 11 with asthma. For Vmax50, use of FVCm instead of FVCp resulted in an error of 8 +/- 7 percent (mean +/- 1 SD) in the normal subjects compared to 32 +/- 23 in those with CF (p less than 0.01) and 24 +/- 18 for those with asthma (p less than 0.05). For Vmax25, the errors were similar. These errors were not predictable from...Continue Reading


Apr 1, 1979·The Journal of Pediatrics·M L LorenR O Buck
Feb 1, 1988·The American Review of Respiratory Disease·K J DesmondA L Coates
Oct 1, 1987·The American Review of Respiratory Disease·M J KrowkaR E Hyatt
Jan 1, 1983·Respiration Physiology·C Gaultier, R Zinman
Jan 1, 1954·The American Journal of Medicine·D L FRYC C BROWN


May 1, 1992·Medical & Biological Engineering & Computing·P Gizdulich
Aug 19, 2007·European Journal of Applied Physiology·Scott J ButcherStewart R Petersen
Dec 31, 1997·American Journal of Respiratory and Critical Care Medicine·M J HaydenP N LeSouëf
Jan 5, 2000·American Journal of Respiratory and Critical Care Medicine·C G IrvinR J Martin
Feb 15, 2019·Frontiers in Physiology·Paolo T Pianosi, Joshua R Smith
Apr 23, 2019·Lung India : Official Organ of Indian Chest Society·Ashutosh Nath AggarwalRakesh Kodati
Feb 19, 1999·Pediatric Pulmonology·D N Pickering, C S Beardsmore
May 1, 2004·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Amir SharafkhanehAladin M Boriek

Related Concepts

Pulmonary Cystic Fibrosis
Forced Expiratory Flow Rates
Lung Volume Measurements
Maximal Expiratory Flow-Volume Curves
Plethysmography, Whole Body

Related Feeds


This feed focuses in Asthma in which your airways narrow and swell. This can make breathing difficult and trigger coughing, wheezing and shortness of breath.

Allergy and Asthma

Allergy and asthma are inflammatory disorders that are triggered by the activation of an allergen-specific regulatory t cell. These t cells become activated when allergens are recognized by allergen-presenting cells. Here is the latest research on allergy and asthma.

Related Papers

Respirology : Official Journal of the Asian Pacific Society of Respirology
Ching-Kai Lin, Ching-Chi Lin
Respiration; International Review of Thoracic Diseases
H von der HardtH Hellweg
© 2021 Meta ULC. All rights reserved