Effect of instillation into lung of autologous blood on pulmonary function and tracheobronchial wash cytology.

The research investigated the effects of simulated pulmonary haemorrhage on lung function and cytology. The study found that instilling blood or saline led to an increase in the number of neutrophils, changes in the thoracic radiographs, but did not affect breathing mechanics or arterial blood gases at rest. However, maximal expiratory peak flow was considerably lower and total pulmonary resistance was significantly higher immediately after the blood instillation.

Study Design and Procedures

• The study was carried out on four healthy horses that were free from exercise-induced pulmonary haemorrhage. The subjects were divided into two groups: Group 1, upon whom the pulmonary haemorrhage was simulated, and Group 2 which served as the control group where the same volume of saline was instilled into the lungs.
• Before the start of the experiment and then 1, 7, 14, and 28 days after instillation, pulmonary function tests including lobeline-induced hyperventilation, cytology of tracheobronchial wash (TBW), and thoracic radiographs were conducted to observe and measure any functional or cytological changes in the lungs.

Findings

• The instillation of either blood or saline into the lungs resulted in an increase in the number of neutrophils in the tracheobronchial wash. Neutrophils are white blood cells that usually increase in response to inflammation or infection.
• Thoracic radiographs showed heightened opacity in the caudodorsal region of the lung in both groups post instillation, attributing these changes to the instillation procedure, not the nature of the instilled material (blood or saline).
• Resting breathing mechanics and arterial blood gases levels were not affected in either group after instillation.
• The major observable difference was in lobeline-induced hyperventilation results: Group 1 showed a lower maximal expiratory peak flow and a higher total pulmonary resistance on the first day following instillation. This implies that expiratory flows might be partly limited in horses experiencing high airflow after bleeding events.

Conclusion

• The effect of simulating pulmonary haemorrhage in horses resulted in observable changes in pulmonary function and cytology. The outcomes offer insights into the potential impact of pulmonary haemorrhage, specifically suggesting limitations on expiratory flows during high airflow situations.