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.
Vet Anaesth Analg
; 45(1): 31-40, 2018 Jan.
Article
em En
| MEDLINE
| ID: mdl-29222030
ABSTRACT
OBJECTIVE:
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. STUDYDESIGN:
Randomized, experimental, crossover study. ANIMALS A total of eight healthy adult horses.METHODS:
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.RESULTS:
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. CONCLUSIONS AND CLINICAL RELEVANCE 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.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Tomografia
/
Espaço Morto Respiratório
/
Ventilação Pulmonar
/
Capnografia
/
Pressão Positiva Contínua nas Vias Aéreas
Limite:
Animals
Idioma:
En
Revista:
Vet Anaesth Analg
Assunto da revista:
ANESTESIOLOGIA
/
MEDICINA VETERINARIA
Ano de publicação:
2018
Tipo de documento:
Article