Electrical impedance tomography to measure lung ventilation distribution in healthy horses and horses with left-sided cardiac volume overload.
Authors: Sacks Muriel, Byrne David P, Herteman Nicolas, Secombe Cristy, Adler Andy, Hosgood Giselle, Raisis Anthea L, Mosing Martina
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary Left-sided cardiac volume overload causes pulmonary oedema that redistributes ventilation within the lungs, yet objective assessment methods in equine practice remain limited. Researchers used electrical impedance tomography (EIT)—a non-invasive imaging technique measuring changes in lung electrical conductivity—to quantify ventilation patterns in eight healthy horses and six with naturally occurring LCVO (four compensated, two decompensated), with serial measurements taken in decompensated cases before and after furosemide administration. Compared to healthy controls, LCVO-affected horses demonstrated significantly reduced left lung ventilation (mean 3.02% less), reciprocal increase in right lung ventilation, and markedly smaller ventilation amplitudes in the left lung (2.54% smaller in the average-maximum measurement and 5.40% smaller in the linear-plane measurement; P ≤ 0.03 for all comparisons). Clinical observations in decompensated horses aligned with EIT findings, and furosemide administration produced measurable changes in the ventilation distribution pattern. As a standing, non-sedated assessment technique, EIT offers farriers, veterinarians and physiotherapists an objective window into how cardiac disease affects pulmonary mechanics—potentially enabling earlier detection of subclinical disease progression and more precise monitoring of therapeutic response in horses with valvular disease or other causes of volume overload.
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Practical Takeaways
- •EIT provides an objective, non-invasive method to assess how cardiac disease is affecting lung ventilation in live horses without sedation, offering a new diagnostic tool for evaluating cardiogenic pulmonary disease
- •Ventilation shifts to the right lung in horses with left-sided cardiac volume overload, suggesting fluid accumulation or compression affecting left lung function—this could guide clinical assessment and treatment monitoring
- •EIT measurements may help distinguish compensated from decompensated LCVO and evaluate treatment response to diuretics, potentially improving early detection of decompensation before overt clinical signs develop
Key Findings
- •Horses with LCVO had significantly less ventilation in the left lung (VAL mean difference 3.02; P = 0.02) and more in the right lung compared to healthy horses
- •LCVO horses showed smaller anterior-posterior ventilation distribution (avg-max V∆ZLine difference 2.54; P = 0.003)
- •EIT alterations in decompensated LCVO horses correlated with clinical signs and responded to furosemide administration
- •Electrical impedance tomography can objectively assess ventilation distribution changes secondary to cardiac disease in standing, unsedated horses