The aim of this study was twofold: to assess the effect of bronchoscopy and bronchoalveolar lavage (BAL) on respiratory function in healthy cats and in experimentally allergen-sensitized cats, and to test whether inhaled bronchodilators would prevent changes in respiratory function during these procedures. Eighteen short-haired cats, aged 10 to 18 months, were used for the study. The cats were divided into 3 groups: 1 control, 1 experimentally sensitized to ovalbumin (OVA), and 1 experimentally sensitized to Ascaris suum. A series of 5 tests was done on the groups, each 10 weeks apart. In the first test, chest radiographs were taken and respiratory function was assessed by barometric whole-body plethysmography (BWBP) on day 1. On day 2, BAL and bronchoscopy were done under anesthesia, with BWBP measurements taken after sedation, after anesthesia induction, and again immediately after bronchoscopy and BAL. The same protocol was followed for the second test, but with the experimental subjects undergoing inhalation challenge and the control subjects exposed to saline on day 0. The protocol used in test 2 was also followed for tests 3, 4, and 5, with the addition of treating the subjects with an inhaled bronchodilator (salbutamol, ipratropium bromide, or a combination of both) immediately before sedation.
The authors concluded that bronchoscopy and BAL induced transient airflow limitation in cats, which was more severe in the presence of lower airway inflammation. They also suggested that use of BWBP as a noninvasive method of determining respiratory function may be a helpful way to detect at-risk patients. Regarding the use of bronchodilators, results obtained in the control and OVA-sensitized groups were unclear, because only the salbutamol plus ipratropium bromide treatment decreased bronchoconstriction in the control group, whereas all treatments tended to be efficient in the OVA-sensitized group. However, the authors were able to conclude that inhaled salbutamol (200 mg) plus ipratropium (40 mg) reduced BAL-induced bronchoconstriction in A. suum-challenged cats and might be recommended as a preventive treatment for asthmatic cats undergoing bronchoscopy.
COMMENTARY: Bronchoscopy and bronchial lavage are being done with increasing frequency in feline patients. Because these procedures cause clinically significant bronchoconstriction in humans, persons undergoing bronchoscopy are routinely pretreated with bronchodilator drugs. The present study documents bronchoscopy-induced bronchoconstriction in normal cats and cats with experimentally induced lower airway disease. It also shows that pretreating these patients with inhaled bronchodilator drugs significantly reduces the lower airway constriction induced by the procedure. This is a clinically significant demonstration of the importance of pretreating all feline patients with inhaled bronchodilators before bronchoscopy.
Bronchodilators in bronchoscopy-induced airflow limitation in allergen-sensitized cats. Kirshvink N, Leemans J, Delvaux F, et al. J VET INTERN MED 19:161-167, 2005.