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Type of publication: Journal Article
Type of document: Full Paper

Year: 2018

Authors: Mosing, M; Auer, U; MacFarlane, P; Bardell, D; Schramel, JP; Böhm, SH; Bettschart-Wolfensberger, R; Waldmann, AD

Title: Regional ventilation distribution and dead space in anaesthetized horses treated with and without continuous positive airway pressure: novel insights by electrical impedance tomography and volumetric capnography.

Source: Vet Anaesth Analg. 2018; 45(1):31-40



Authors Vetmeduni Vienna:

Auer Ulrike
Schramel Johannes

Vetmed Research Units
University Clinic for Small Animals, Clinical Unit of Anaesthesiology and Perioperative Intensive-Care Medicine


Abstract:
The aim of this study was to evaluate the effect of continuous positive airway pressure (CPAP) on regional distribution of ventilation and dead space in anaesthetized horses.Randomized, experimental, crossover study.A total of eight healthy adult horses.Horses were anaesthetized twice with isoflurane in 50% oxygen and medetomidine as continuous infusion in dorsal recumbency, and administered in random order either CPAP (8 cmH2O) or NO CPAP for 3 hours. Electrical impedance tomography (and volumetric capnography (VCap) measurements were performed every 30 minutes. Lung regions with little ventilation [dependent silent spaces (DSSs) and nondependent silent spaces (NSSs)], centre of ventilation (CoV) and dead space variables, as well as venous admixture were calculated. Statistical analysis was performed using multivariate analysis of variance and Pearson correlation.Data from six horses were statistically analysed. In CPAP, the CoV shifted to dependent parts of the lungs (p < 0.001) and DSSs were significantly smaller (p < 0.001), while no difference was seen in NSSs. Venous admixture was significantly correlated with DSS with the treatment time taken as covariate (p < 0.0001; r = 0.65). No differences were found for any VCap parameters.In dorsally recumbent anaesthetized horses, CPAP of 8 cmH2O results in redistribution of ventilation towards the dependent lung regions, thereby improving ventilation-perfusion matching. This improvement was not associated with an increase in dead space indicative for a lack in distension of the airways or impairment of alveolar perfusion.Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.

Keywords Pubmed: Anesthesia, Intravenousmethodsveterinary
Animals
Capnographymethodsveterinary
Continuous Positive Airway Pressuremethodsveterinary
Cross-Over Studies
Electric Impedance
Horses
Pulmonary Ventilationphysiology
Respiratory Dead Spacephysiology
Tomographymethodsveterinary

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