Background: The immune response is affected by anaesthesia and surgery. This study was carried out on the effects of open heart surgery on the oral mucous host defence system, which is part of the common mucosal immune system.
Methods: Amylase, nonimmunological (lysozyme, myeloperoxidase, hypothiocyanite and thiocyanate) and immunological (IgA, IgG, and IgM) mucous host defence factors as well as oral bacterial flora were determined in the saliva of 18 patients undergoing open heart surgery preoperatively and on the 2nd, 3rd, and 7th postoperative days. To assess the specificity of the changes, the salivary flow rate and total protein content were also determined.
Results: Stimulated salivary flow decreased from 1.8 (1.3-2.2) ml/min (median; 25th and 75th quartiles) to 0.4 (0.3-0.5) ml/min by the 2nd postoperative day and to 0.4 (0.2-1.0) ml/min by the 3rd postoperative day (P < 0.001). Amylase, lysozyme, myeloperoxidase, total salivary peroxidase and thiocyanate levels increased, whereas hypothiocyanite levels decreased postoperatively (p < 0.01-0.001). Their total secretion rate, however, was reduced (P < 0.05-0.001) owing to the lowered salivary flow rate. IgG and IgM concentrations were raised on the 2nd, 3rd and 7th postoperative days (P < 0.05-0.001), and IgA concentrations on the 2nd postoperative day (P < 0.05). The total secretion of IgG and IgM as well as their salivary concentrations in relation to total protein concentrations also increased. The number of salivary anaerobically growing bacteria decreased postoperatively (P < 0.01), but the number of salivary streptococci remained unaffected.
Conclusions: Open heart surgery decreases the salivary secretion of nonimmunological host defence factors and increases the salivary secretion of IgA, IgG and IgM.