The variability and repeatability of indices derived from the single-breath diagram for CO2 in horses with chronic obstructive pulmonary disease and the effect of lobelin hydrochloride on these indices
C. Herholz et al., The variability and repeatability of indices derived from the single-breath diagram for CO2 in horses with chronic obstructive pulmonary disease and the effect of lobelin hydrochloride on these indices, VET RES COM, 25(5), 2001, pp. 401-412
Several indices of ventilatory heterogeneity can be identified from the vol
umetric capnogram and its graphic presentation, the single-breath diagram f
or CO2 (SBD-CO2). Physiologically based indices of pulmonary function (VTE,
VCO2, FACO2, VDBohr, VDBohr%, VD/VTE, A(1)/A(2)) were calculated for healt
hy horses (group I, n = 5) and for horses with subclinical (group II, n = 7
) or clinically manifest chronic obstructive pulmonary disease (COPD) (grou
p III, n = 8) during tidal breathing and after medication with lobelin hydr
ochloride (Lobelin). We investigated the variability and repeatability of t
he lung function indices in healthy horses and in those with COPD both duri
ng tidal breathing and after administration of Lobelin, a centrally acting
respiratory stimulant. In particular, we were interested in whether the dis
criminating ability of SBD-CO2-derived lung function indices would be incre
ased between different patient groups after administration of Lobelin compa
red to those for the resting values. Of the indices studied, VTE, FACO2, VD
Bohr% and A(1)/A(2) appeared to be those with good to excellent repeatabili
ty in discriminating healthy horses from those with COPD. Stimulating respi
ration with Lobelin gave no advantage in the repeatability of the lung func
tion indices or in differentiating between horses with different degrees of
COPD.