Effects of perineural capsaicin treatment on cardiopulmonary reflexes elicited by laryngeal instillations of capsaicin and distilled water in sevoflurane-anesthetized dogs

The aim of this study was to determine the effect of perineural capsaicin ( CAPS) treatment on cardiopulmonary reflexes elicited by topical laryngeal i nstillation of CAPS and distilled water (DW) in sevoflurane-anesthetized do gs. Cardiopulmonary reflexes elicited by CAPS (10 mu g/ml, 10 ml) were atte nuated by perineural CAPS treatment to the superior laryngeal nerves (SLNs) (P<0.05), whereas those by DW (10 ml) remained unaffected (P>0.05). The re flex responses to DW that remained even after the perineural CAPS treatment were eliminated by laryngeal anesthesia with lidocaine. These results sugg est that cardiopulmonary reflexes from the laryngeal mucosa elicited by CAP S instillation can be blocked by perineural CAPS treatment to the SLNs, whi ch may result from inhibition of the laryngeal sensitive C-fiber afferents.