An evaluation of the multiple-breath nitrogen washout as a pulmonary function test in horses.
Abstract: Multiple-breath nitrogen washouts (MBNW) were performed with 29 light horses. Seven normal horses were used to examine the reproducibility, and 22, ranging from normal to severely diseased, were used to examine the changes in chronic obstructive pulmonary disease (COPD) and the effect of a bronchodilator, salbutamol, on the distribution of ventilation. The MBNW were analyzed using the functional residual capacity (FRC), end-tidal N2 concentration of the final breath of the MBNW (FETN2,fb), end-tidal N2 concentration when the cumulative expired volume was equal to body weight (FETN2,bw), lung clearance index (LCI), Becklake index (BI), mixing ratio (MR), index of distribution of inspiration (IDI), pulmonary N2 clearance delay (PCD) and ventilatory efficiency (EFF). The LCI, MR, IDI, PCD and EFF were calculated at end-tidal N2 concentrations (FETN2), equal to 3%, 2% and FETN2,fb. The EFF was also calculated at FETN2 = 8%, as was BI. The within day coefficient of variation for most indices of the MBNW was 10-15%. None of the indices varied significantly from day-to-day. The FETN2,fb, FETN2,bw, MR, IDI, PCD, and EFFfb, EFF3% and EFF2% differed between the horses with COPD and the normal horses, and all of the indices, except FRC, were correlated with a histopathological score of the small airways. The FETN2,bw appeared to be the most sensitive index in detecting the horses with COPD. In the horses with COPD, salbutamol caused a decrease in FRC and FETN2,fb indicating increased ventilation of the lung. However, LCI increased suggesting a less efficient distribution of ventilation.
Publication Date: 1990-01-01 PubMed ID: 2306677PubMed Central: PMC1255612
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Beta2 Agonist
- Bronchodilation
- Chronic Obstructive Pulmonary Disease
- Clinical Pathology
- Clinical Study
- Diagnostic Technique
- Disease Diagnosis
- Disease Treatment
- Equine Health
- Horses
- Lung Health
- Pathophysiology
- Pharmacodynamics
- Pharmacology
- Physiology
- Pulmonary Health
- Respiratory Disease
- Respiratory Health
- Veterinary Medicine
- Veterinary Research
Summary
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The study investigates the efficacy of Multiple-breath nitrogen washouts (MBNW) in assessing lung function in horses. It evaluates changes in horses with chronic obstructive pulmonary disease (COPD) and the impact of a bronchodilator, with a particular focus on how ventilation is distributed.
Methodology and Participants
- The research involved 29 light horses in total. Of this number, seven were healthy and used to gauge the reproducibility of the MBNW analysis. In contrast, the remaining 22 featured a mix of healthy horses and those with varying severity of COPD disease. These were used to study the changes elicited by COPD, and how administering a bronchodilator, specifically salbutamol, affects ventilation distribution.
Indices Used in Analysis
- Different indices were used to analyze the MBNW, including: Functional residual capacity (FRC), the end-tidal N2 concentration of the final breath of the MBNW (FETN2,fb), end-tidal N2 concentration when the cumulative expired volume was equal to body weight (FETN2,bw), lung clearance index (LCI), Becklake index (BI), mixing ratio (MR), index of distribution of inspiration (IDI), pulmonary N2 clearance delay (PCD), and ventilatory efficiency (EFF).
- Several of these indices, such as LCI, MR, IDI, PCD, and EFF, were computed at 3%, 2%, and FETN2,fb end-tidal N2 concentrations. EFF and BI were also determined at an 8% FETN2 concentration.
Reproducibility and Day-to-Day Variability
- The within-day coefficient of variation for most indices of the MBNW was found to be between 10-15%, indicating a reasonable degree of precision.
- No significant differences were observed in the indices from one day to the next, suggesting this method has good reliability.
Comparing COPD and Healthy Horses
- Certain indices like FETN2,fb, FETN2,bw, MR, IDI, PCD, and EFFfb, EFF3%, and EFF2% were found to differ between normal horses and those suffering from COPD.
- All of the indices, except for FRC, correlated with a histopathological score which categorized the level of damage caused to the small airways of the lungs by disease.
- The most sensitive index for identifying horses with COPD was FETN2,bw.
Effect of Bronchodilator
- On administering salbutamol, the study noted a decrease in FRC and FETN2,fb. This result is indicative of increased lung ventilation.
- However, an observed rise in LCI suggests a less efficient distribution of ventilation in horses with COPD upon using a bronchodilator.
Cite This Article
APA
Gallivan GJ, Viel L, McDonell WN.
(1990).
An evaluation of the multiple-breath nitrogen washout as a pulmonary function test in horses.
Can J Vet Res, 54(1), 99-105.
Publication
Researcher Affiliations
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph.
MeSH Terms
- Animals
- Evaluation Studies as Topic
- Horse Diseases / diagnosis
- Horse Diseases / physiopathology
- Horses / physiology
- Lung Diseases, Obstructive / diagnosis
- Lung Diseases, Obstructive / physiopathology
- Lung Diseases, Obstructive / veterinary
- Nitrogen
- Respiration / physiology
- Respiratory Function Tests / methods
- Respiratory Function Tests / veterinary
References
This article includes 20 references
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Citations
This article has been cited 3 times.- Dharmakumara M, Prisk GK, Royce SG, Tawhai M, Thompson BR. The effect of gas exchange on multiple-breath nitrogen washout measures of ventilation inhomogeneity in the mouse.. J Appl Physiol (1985) 2014 Nov 1;117(9):1049-54.
- Herholz C, Straub R, Busato A. Ultrasound-spirometry and capnography in horses: analysis of measurement reliability.. Vet Res Commun 2001 Feb;25(2):137-47.
- Gauvreau GM, Young SS, Staempfli H, McCutcheon LJ, Wilson BA, McDonell WN. The relationship between respiratory exchange ratio, plasma lactate and muscle lactate concentrations in exercising horses using a valved gas collection system.. Can J Vet Res 1996 Jul;60(3):161-71.
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