Influence of bronchoalveolar lavage volume on cytological profiles and subsequent diagnosis of inflammatory airway disease in horses.

This research study investigates how the volume of saline solution used in a bronchoalveolar lavage (BAL) procedure affects the detection of inflammatory airway disease (IAD) in horses. The researchers found that the volume used can significantly impact the diagnostic outcome.

Research Approach

• The researchers conducted the study on thirty Standardbred racehorses, owned by clients, showing potential symptoms of IAD. They used an endoscope to instill two different volumes of saline solution into each horse’s lungs—250 mL in one and 500 mL in the other—to perform the BAL procedures.
• The same process was repeated 72 hours later, but the saline volumes were switched between the lungs. This ensured each lung was tested with both volumes. The purpose was to identify whether using different amounts of saline would affect the composition of the fluids recovered, and thus, the diagnosis of IAD.

Findings

• Results indicated that the percentage of BAL fluid (BALF) recovered from each lung was significantly higher when a larger volume (500 mL) of saline was used.
• Interestingly, the percentage of neutrophils (a type of white blood cell that increases in response to inflammation or infection) found was statistically lower when the larger volume was used.
• When considering the proportions of neutrophils (>10% from at least one lung) for the diagnosis of IAD, poor agreement was found between the uses of two different volumes of saline. This suggests that the volume used can significantly influence the diagnosis.

Implications

• This study revealed that the volume of saline solution instilled into the lung during a BAL procedure can significantly influence the cytological profiles obtained. This has impacts on diagnosis and possible misdiagnosis of IAD.
• Given these findings, the researchers concluded that there is a need to establish specific reference values for BALF. This would aid in standardizing the BAL procedure and potentially lead to more accurate diagnostic outcomes.