Statistical Shape Analysis of Volumetric Capnograms: Evaluation of a New Approach for the Assessment of Pulmonary Function in Horses with Chronic Obstructive Pulmonary Disease

Abstract

The shape of the volumetric capnogram is modified by airway obstruction, and the evaluation of this deformation could allow an indirect measurement of bronchial patency. The study included 35 horses; five horses without evidence of pulmonary disease (group I) and 30 horses suffering from different degrees of chronic obstructive pulmonary disease (COPD) (groups II-IV). Data of recorded CO2 and volume curves were off-line plotted and statistically analysed using regression analysis. Analyses were performed separately for fractions 25-95% (VTE25-95), 25-50% (VTE25-50) and 50-95% (VTE50-95) of expiratory tidal volume. For VTE25-95 estimates of linear and quadratic regression parameters were significantly different between groups. For VTE25-50 linear terms were significant in all clinical groups and decreased considerably from group I to group IV. Linear and quadratic terms for VTE50-95 were significant in all clinical groups and increased with the severity of COPD. The difference of total expiratory CO2 volume was significant between all groups. Statistical analysis of the volumetric capnogram is a precise method for description of shape deformities of the single breath diagram for CO2 (SBD-CO2) in horses with COPD and global models including phase II and III of the SBD-CO2 are helpful in the detection of pulmonary function impairment. However, although the model of the statistical shape analysis of the SBD-CO2 is precise, it may not necessarily be a useful test to discriminate horses with minor, moderate and severe COPD for clinical use.

Comparison of the Clearance of 99mTechnetium‐DTPA From the Lung and Lung Function Indices Derived From the Single Breath Diagram for Carbon Dioxide in Horses with Chronic Obstructive Pulmonary Disease

“…This transport impairment is re¯ected in typical changes in the CO 2 washout pro®le, such as increased phase III slopes and a blurring of the transition between phases II and III. These typical changes in the SBD-CO 2 have also been reported in horses suffering from COPD by Herholz et al (2001b). Therefore the SBD-CO 2 predominantly re¯ects the distribution of ventilation and may help to identify alveolar dead space ventilation and/or ventilatory inhomogeneity.…”

“…Depending on their clinical status of pulmonary health the horses were divided into healthy horses and horses suffering from subclinical, minor, and moderate to severe COPD as described elsewhere (Herholz et al, 2001b).…”

Recurrent airway obstruction: A review

“…Consequently, alternative more sensitive methods have been evaluated in recent years. These include impulse oscillometry, which measures respiratory resistance and reactance at various frequencies [141,[150][151][152][153], tidal breathing flowvolume loops [154], volumetric capnography [155][156][157][158] and forced expiratory flow-volume curve analysis [148,159,160], with the most discriminatory and commonly employed method at present being impulse oscillometry.…”

The Ability of Volumetric Capnography to Distinguish between Chronic Obstructive Pulmonary Disease Patients and Normal Subjects

“…Many indices, including the slopes of phases II and III and estimates of dead space [7][8][9], can be deduced using VCap, and it is of proven value in the clinical assessment of a number of diseases, including pulmonary thromboembolism [10][11][12][13], interstitial lung disease [14], and acute lung injury [15,16]; it is also used to assess patients undergoing mechanical ventilation [17][18][19][20][21]. The shape of the VCap curve in patients with obstructive lung diseases such as COPD and asthma differs from those of normal subjects and patients with restrictive lung disease [22][23][24][25]. A number of parameters measured by VCap are considered useful for classifying the extent of airflow limitation among patients diagnosed with COPD [26].…”