Functional assessment of expiratory flow pattern in feline lower airway disease

Abstract

Feline lower airway disease (FLAD) is a chronic respiratory disease of which there is a lack of information on functional assessment in current veterinary medicine. The purposes of this study were to investigate expiratory pattern and evaluate the diagnostic utility of functional parameters in cats with FLAD. Thirty-three client-owned cats (23 FLAD cats and 10 control cats) were studied. Under quiet tidal breathing, pseudo-tidal breathing flow-volume loop (pTBFVL) was obtained from a barometric whole body plethysmography (BWBP) device. There were significant differences in the shapes of expiratory, but not inspiratory, curves between FLAD and control cats. The incidence of the presence of concave expiratory curve indicating lower airway obstruction was 74% in FLAD cats. To assess the diagnostic utility of pTBFVL indices in cats with FLAD, area under the receiver-operator curve was 0.86 for PEF/EF50 (peak expiratory flow divided by expiratory flow at end expiratory volume plus 50% tidal volume); a cuff-off value of PEF/EF50 >1.51 distinguished normal from FLAD (73.9% sensitivity, 100% specificity). There were no significant differences in traditionally measured BWBP parameters (ie, enhanced pause) between cats with and without FLAD in the present study. In conclusion, underlying change on expiratory flow pattern during natural tidal breathing existed in FLAD cats, and selected pTBFVL indices were useful in discriminating FLAD from normal cats. Tidal breathing pattern depicted by pseudoflow-pseudovolume loops from a BWBP system could be a non-invasive tool for functional assessment in client-owned cats.

Functional Phenotype and its Correlation with Therapeutic Response and Inflammatory Type of Bronchoalveolar Lavage Fluid in Feline Lower Airway Disease

“…The pressure signal of the system was calibrated before each measurement by dynamic injection of 50 mL air into the chamber. Under quiet tidal breathing, the pseudotidal breathing flow‐volume loop (pTBFVL) and conventionally‐used BWBP parameters were acquired at the same time as described elsewhere . Artifactual waveforms caused by sniffing, vocalization, and body movements were automatically excluded and manually eliminated by the rejection setting of the commercial software (BioSystem XA 2.11.0 software) and simultaneous visual inspection, respectively.…”

“…Although decreased airway responsiveness after treatment with steroids or bronchodilators could be evaluated by bronchoprovocation testing in experimental cats, bronchospasm at presentation prohibits further provocative stimulation and limits the ability to compare the provocative index before and after treatment in client‐owned cats. Aside from conventionally measured BWBP parameters and airway responsiveness testing, breathing pattern depicted by pseudoflow and pseudovolume may indirectly estimate respiratory mechanics during tidal breathing . The occurrence of small airway obstruction in cats with FLAD can result in substantial airflow limitation in the mid‐ to late‐expiratory phase, and a peak to midexpiratory flow ratio >1.51 identifies this obstructive pattern during tidal breathing .…”

“…Aside from conventionally measured BWBP parameters and airway responsiveness testing, breathing pattern depicted by pseudoflow and pseudovolume may indirectly estimate respiratory mechanics during tidal breathing . The occurrence of small airway obstruction in cats with FLAD can result in substantial airflow limitation in the mid‐ to late‐expiratory phase, and a peak to midexpiratory flow ratio >1.51 identifies this obstructive pattern during tidal breathing . We believe that with clinical improvement after treatment, respiratory function should also show improvement.…”

Characterisation of Brachycephalic Obstructive Airway Syndrome in French Bulldogs Using Whole-Body Barometric Plethysmography

“…Whole-body barometric plethysmography (WBBP) is a non-invasive and objective technique to measure respiratory function while the animal is fully conscious and minimally restrained [17–23]. The animal rests in the WBBP chamber and respiration causes barometric pressure oscillations proportional to tidal volume.…”

Whole‐Body Barometric Plethysmography Characterizes Upper Airway Obstruction in 3 Brachycephalic Breeds of Dogs

“…Whole‐body barometric plethysmography (WBBP) is a non‐invasive technique of measuring respiratory function that has been validated and utilized in unrestrained unsedated experimental mice to characterize respiratory patterns during sleep and wakefulness . This technique has also been used in experimental and clinical studies using dogs and cats for pharmacological studies and respiratory disorders . Our previous study on French bulldogs showed that respiratory airflow characteristics obtained from WBBP are distinguishable between BOAS‐affected and clinically healthy French bulldogs .…”