Effect of a syringe aspiration technique versus a mechanical suction technique and use of N-butylscopolammonium bromide on the quantity and quality of bronchoalveolar lavage fluid samples obtained from horses with the summer pasture endophenotype of equine asthma

Abstract

OBJECTIVE To evaluate the effect of 2 bronchoalveolar lavage (BAL) sampling techniques and the use of N-butylscopolammonium bromide (NBB) on the quantity and quality of BAL fluid (BALF) samples obtained from horses with the summer pasture endophenotype of equine asthma. ANIMALS 8 horses with the summer pasture endophenotype of equine asthma. PROCEDURES BAL was performed bilaterally (right and left lung sites) with a flexible videoendoscope passed through the left or right nasal passage. During lavage of the first lung site, a BALF sample was collected by means of either gentle syringe aspiration or mechanical suction with a pressure-regulated wall-mounted suction pump. The endoscope was then maneuvered into the contralateral lung site, and lavage was performed with the alternate fluid retrieval technique. For each horse, BAL was performed bilaterally once with and once without premedication with NBB (21-day interval). The BALF samples retrieved were evaluated for volume, total cell count, differential cell count, RBC count, and total protein concentration. RESULTS Use of syringe aspiration significantly increased total BALF volume (mean volume increase, 40 mL [approx 7.5% yield]) and decreased total RBC count (mean decrease, 142 cells/μL), compared with use of mechanical suction. The BALF nucleated cell count and differential cell count did not differ between BAL procedures. Use of NBB had no effect on BALF retrieval. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that retrieval of BALF by syringe aspiration may increase yield and reduce barotrauma in horses at increased risk of bronchoconstriction and bronchiolar collapse. Further studies to determine the usefulness of NBB and other bronchodilators during BAL procedures in horses are warranted.

Effect of Lavage Solution Type on Bronchoalveolar Lavage Fluid Cytology in Clinically Healthy Horses

“…A study performed by Bowser et al (2018) evaluated the effect of manual (syringe) aspiration versus mechanical suction [ 30 ], showing a larger volume of BAL fluid recovered and a lower total red blood cell (RBC) count after manual aspiration compared with mechanical suction [ 31 ]. Corroborating this, erythrocytes were not detected in BAL fluid in our study, suggesting that the BAL procedure with manual aspiration is safe.…”

“…Orard et al (2016) studied the influence of BAL volume (250 mL versus 500 mL of saline) on cytological profiles, finding a lower total cell count and neutrophil percentage with the larger volume [29]. There was poor agreement between the findings when 250 mL or 500 mL of BAL solution was used for diagnosing inflammatory airway disease, with a similar proportion of horses being classified as healthy or having inflammatory airway disease [30]. Sweeney et al (1992) reported a higher percentage of neutrophils and a lower percentage of mast cells when a smaller volume (50 mL) was used compared with a larger volume (350 mL) [27].…”