Comparison of inulin with urea as dilutional markers of bronchoalveolar lavage in healthy and heaves-affected horses

Abstract

-Solute analysis in bronchoalveolar lavage fluid involves the use of dilutional markers to correct for variable recovery of pulmonary epithelial lining fluid (PELF). Urea is the best characterised endogenous marker, whereas inulin appears to meet the requirements of an exogenous marker. In horses, the use of inulin has never been investigated and the impact of lower airway diseases such as heaves, on PELF recovery is unknown. In this study, five healthy and five heaves-affected horses underwent airway endoscopy and bronchoalveolar lavage. PELF recovery from bronchoalveolar lavage was calculated by the inulin and the urea method. The inulin method was compared to the urea method and differences between healthy and heaves-affected horses were analysed. From a technical and analytical point of view, inulin fulfilled the requirements of a marker of dilution as well as urea. When both healthy and heaves-affected horses groups were pooled together, PELF recovery calculated by the inulin method was significantly higher than by the urea method (6.43 ± 4.08% versus 0.789 ± 0.299%, P < 0.005). No significant differences were observed between healthy and heaves-affected horses, neither by the inulin nor by the urea method. Inulin did not present major advantages over urea, but the combined use of both markers can improve the standardisation of studies comparing PELF compounds, by providing upper limits (inulin dilution) and lower limits (urea dilution) of PELF recovery.inulin / urea / bronchoalveolar lavage / dilution factor Résumé -Comparaison de l'inuline et de l'urée en tant que marqueurs de dilution de lavage bronchoalvéolaire chez des chevaux sains et des chevaux poussifs. L'analyse des composants du liquide de lavage bronchoalvéolaire implique fréquemment l'utilisation de facteurs de dilution afin de pouvoir corriger la récupération très variable du fluide épithélial pulmonaire (FEP). Parmi les marqueurs utilisés, l'urée est le marqueur endogène le mieux caractérisé, tandis que l'inuline possède toutes les caractéristiques requises d'un marqueur de dilution exogène. L'inuline n'a jamais été Vet. Res. 32 (2001) 145-154 145

Ureia como marcador de diluição em amostras de lavado traqueobrônquico de potros com rodococose

“…A grande dificuldade encontrada na investigação de componentes de fluídos pulmonares é a variação quanto ao volume e composição do fluído recuperado. Essa variação implica em limitação na interpretação das mensurações de soluto, por isso é necessária a utilização de um marcador que indique o grau de diluição do fluído recuperado (Reynolds 1987, Kirschvink et al 2001). …”

“…Os marcadores endógenos mais comumente utilizados são a ureia e a albumina (Von Wichert et al 1993, Dargaville et al 1999, Kirschvink et al 2001, Mohamed et al 2001, Fahy et al 2001, Ziglam et al 2002, Bertagnon et al 2007). Proteína total, sódio, cloreto e IgA secretória também foram estudadas (Von Wichert et al 1993, Dargaville et al 1999.…”

Antimicrobial drug concentrations and sampling techniques in the equine lung

“…For example, Kirschvink et al (2001) found large differences for the two dilution markers, inulin and urea, when estimating the PELF fraction in equine BAL samples. Other experiences from human studies are that PELF recoveries are typically less than 10% of the BAL sample.…”

“…Inulin, an inert high molecular weight (5 kDa) polysaccharide, has been evaluated as a dilution marker in humans (Restrick et al, 1995) and horses (Kirschvink et al, 2001) and compared with urea. In both studies, inulin was found suitable and safe as a dilution marker.…”

Increased adenosine concentration in bronchoalveolar lavage fluid of horses with lower airway inflammation

“…The mobile phase consisted of linear gradient changes of 0.1% formic acid in water and 0.1% formic acid in methanol. The use of dilutional markers has been investigated in the horse, but remains a matter of controversy (Kirschvink et al, 2001). To avoid dilutional artefact, urea concentrations were determined (QuantiChrom assay, BioAssay Systems) in both in BAL and serum samples that had been collected simultaneously.…”