Can bronchoconstriction and bronchodilatation in horses be detected using electrical impedance tomography?. (11th May 2021)

• Record Type: Journal Article
• Authors: Secombe, Cristy; Adler, Andy; Hosgood, Giselle; Raisis, Anthea; Mosing, Martina
• Is Part Of: Journal of veterinary internal medicine. Volume 35:Number 4(2021)
• Page Start: 2035
• Page End: 2044
• Publication Date: 2021-05-11
• Subjects: albuterol -- equine -- equine asthma -- flow volume loop -- flowmetric plethysmography -- pulmonary function test; Veterinary medicine -- Periodicals; 636.0896
• DOI: 10.1111/jvim.16152
• Languages: English
• ISSNs: 0891-6640

Abstract

Abstract: Background: Electrical impedance tomography (EIT) generates images of the lungs based on impedance change and was able to detect changes in airflow after histamine challenge in horses. Objectives: To confirm that EIT can detect histamine‐provoked changes in airflow and subsequent drug‐induced bronchodilatation. Novel EIT flow variables were developed and examined for changes in airflow. Methods: Bronchoconstriction was induced using stepwise histamine bronchoprovocation in 17 healthy sedated horses. The EIT variables were recorded at baseline, after saline nebulization (control), at the histamine concentration causing bronchoconstriction (Cmax ) and 2 and 10 minutes after albuterol (salbutamol) administration. Peak global inspiratory (PIFEIT ) and peak expiratory EIT (PEFEIT ) flow, slope of the global expiratory flow‐volume curve (FVslope ), steepest FVslope over all pixels in the lung field, total impedance change (surrogate for tidal volume; VTEIT ) and intercept on the expiratory FV curve normalized to VTEIT (FVintercept /VTEIT ) were indexed to baseline and analyzed for a difference from the control, at Cmax, 2 and 10 minutes after albuterol. Multiple linear regression explored the explanation of the variance of Δflow, a validated variable to evaluate bronchoconstriction using all EIT variables. Results: At Cmax, PIFEIT, PEFEIT, and FVslope significantly increased whereas FVintercept /VT decreased. All variables returned to baseline 10 minutes after albuterol. The VTEIT did not change. Multivariable investigation suggested 51% of Δflow variance was explained by a combination of PIFEIT and PEFEIT . Conclusions and Clinical Importance: Changes in airflow during histamine challenge and subsequent albuterol administration could be detected by various EIT flow volume variables.