title: Distribution of ventilation in pregnant Shetland ponies measured by Electrical Impedance Tomography.
abstract: The regional distribution of ventilation in conscious standing pregnant Shetland pony mares was investigated by Electrical Impedance Tomography (EIT). Six ponies were repeatedly examined a minimum of four weeks prior to (antepartum, AP) until three weeks after parturition (postpartum, PP). From the cross-sectional ventilation image the ventral to dorsal (V/D), left to right (L/R) ventilation distribution ratio and the relative ventilation in four horizontal regions of interest (ROI) placed symmetrically in the chest was analyzed. Antepartum V/D was 0.74 ± 0.09 on day -28 ± 3 (AP28) and decreased to 0.68 ± 0.10 on day -3 ± 2 (AP3). Postpartum V/D increased significantly (p<0.05) to 0.96 ± 0.08 on day 7 ± 2 (PP7). The L/R ventilation distribution remains unaffected. Ventilation in the most ventral ROI was significantly lower on days AP28 and AP3 compared to PP7. These results suggest that in Shetland ponies late pregnancy compromises the ventilation in ventral (dependent) lung regions. We demonstrated the feasibility of a repeated EIT measurement in standing conscious ponies.
authors.affiliation: Division of Anaesthesiology and perioperative Intensive Care, Vetmeduni Vienna, 1210 Vienna, Austria. johannes.schramel@vetmeduni.ac.at
authors.forename: Johannes
authors.initials: J
authors.lastname: Schramel
authors.forename: Christina
authors.initials: C
authors.lastname: Nagel
authors.forename: Ulrike
authors.initials: U
authors.lastname: Auer
authors.forename: Franziska
authors.initials: F
authors.lastname: Palm
authors.forename: Christine
authors.initials: C
authors.lastname: Aurich
authors.forename: Yves
authors.initials: Y
authors.lastname: Moens
mesh_terms: D000818:Animals; D001835:Body Weight; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D005260:Female; D006112:Gravitation; D006736:Horses / Q000502:physiology*; D008168:Lung / Q000502:physiology; D049590:Postpartum Period; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D013990:Tidal Volume; D014054:Tomography