Depression of host-defence mechanisms following cardiac surgery

Handwashing before entering the intensive care unit: what we learned from continuous video-camera surveillance

Handwashing is one of the most important factors in controlling the spread of bacteria and in preventing the development of infections. This simple procedure does not have a high compliance rate. The Association for Professionals in Infection Control and Epidemiology, Inc, guideline recommends that hands must be washed before and after patient contact. In our intensive care unit (ICU), we have made it a rule that everyone should wash their hands before entering the ICU. The purpose of this study was to ascertain the handwashing compliance of all personnel and visitors to the ICU. A ceiling-mounted video camera connected to a time-lapse video cassette recorder recorded each person's actions when they entered the ICU during a 7-day period. Handwashing compliance was assessed for 3 different categories: ICU personnel, non-ICU personnel, and visitors to patients. There were 1030 entries to the ICU during the observation period. ICU personnel complied with handwashing in 71% of entries, non-ICU personnel in 74% of entries, and visitors to patients in 94% of entries. Handwashing compliance by visitors to patients was significantly higher than among personnel (P <.001). Handwashing compliance among personnel before entering the ICU was low. Continuous effort is needed to raise awareness of the handwashing issue, not only to ensure compliance with APIC recommendations but also in our facility, to ensure that health care personnel wash their hands on entry to the ICU.

Effects of open heart surgery on oral mucous host defence systems

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.

Effects of anaesthesia and surgery on the immune response

Alterations have been found to occur in every component of immune response during anaesthesia and surgery. These alterations represent the body's general physiological responses and are mainly dependent on the extent of surgery, as well as other factors such as the patient's age and health status, medication and blood transfusion. Anaesthetic and operative complications have profound effects on these responses. Basically, the immune response to anaesthesia and surgery is a beneficial reaction, needed in local host defences and wound healing and in preventing the body from making autoantibodies against its own tissues. The responses may, however, contribute to the development of postoperative infections and spread of malignant disease. During uncomplicated conventional surgery, the immune response usually passes clinically unnoticed without any harmful effects. Absent responses and excessively high responses, on the other hand, harm the patient. Our understanding of immunological phenomena and our possibilities of controlling mediator activation are now lagging behind the technical advances made in operative treatment. If we want to decrease operative morbidity and mortality to below their present levels, more attention should be directed to immune responses to major surgery, injuries and operative complications with massive mediator release which place the surgical patient at risk. Experimental evidence suggests that results of treatment in injured and operated patients can in the future be improved by controlling immune responses and their mediator systems. Our current level of knowledge of immune responses is already helping us to avoid many immune-mediated complications. However, routine interference with these responses is not indicated.