Influence of cardiopulmonary bypass on some host defence functions in man

Effects of colloidal resuscitation fluids on reticuloendothelial function and resistance to infection after hemorrhage

The effects of three resuscitation fluids, hydroxyethyl starch (HES), Haemaccel, and fresh autologous blood, on reticuloendothelial system phagocytic and catabolic functions and resistance to infection after 40% hemorrhages in BALB/c mice were studied. The mice, anesthetized with isoflurane, were bled over a 10-min period, left hypovolemic for 30 min, and then resuscitated with their shed blood or the same volume of asanguineous fluid. Normothermia was maintained throughout the experiments. The uptake and catabolism of intravenously injected double-labelled sheep erythrocytes (51Cr-125I-SRBC) in liver and spleen were determined at 1 and 48 h after hemorrhage. No significant changes in the uptake or catabolism of SRBC in liver or spleen were found at 1 h after hemorrhage and resuscitation with any of the fluids. However, at 48 h a significant increase in liver uptake of SRBC was seen in animals resuscitated with either Haemaccel or HES compared to that in animals resuscitated with shed blood or in animals subjected to a sham operation. The increase in liver uptake was accompanied by a small decrease in spleen uptake in animals resuscitated with Haemaccel but not with HES. No great changes in catabolic activity were seen at 48 h, although activity levels tended to be higher in animals resuscitated with Haemaccel. Separate groups of animals were challenged by an intraperitoneal injection with live Escherichia coli at 1 or 48 h after hemorrhage and resuscitation. Sixty-four percent of the animals resuscitated with shed blood survived the challenge with E. coli at 1 h after hemorrhage, whereas only 10 and 0% survival was seen for animals resuscitated with Haemaccel and HES, respectively. At 48 h survival was 80% for shed-blood-resuscitated animals and 60 and 70% for Haemaccel- and HES-resuscitated animals, respectively.

Granulocyte phagocytic function is impaired during cardiopulmonary bypass

BACKGROUND

The presence of impaired phagocytic function of the reticuloendothelial system after cardiac operations using cardiopulmonary bypass remains controversial.

METHODS

In this study, the phagocytic function of granulocytes in 14 patients undergoing cardiac operations with cardiopulmonary bypass was examined using a chemiluminescence method. Seven patients with abdominal aortic aneurysms served as controls. Electron microscopy also was employed to evaluate morphologic changes.

RESULTS

The 14 cardiac patients showed impaired phagocytic function from immediately after operation until 12 hours after the operation. This phagocytic function recovered within 24 hours. The 7 control patients showed no change in phagocytic function during or after the operation. Scanning electron microscopic examination of the cardiac patients' granulocytes revealed the loss of villi on cell surfaces immediately after operation. However, these villi were restored within 24 hours after the operation.

CONCLUSIONS

The phagocytic function of granulocytes was impaired in the early postoperative period in patients undergoing cardiopulmonary bypass, and this was probably due to the loss of villi on granulocyte surfaces.

Is it true that cardiac operations with cardiopulmonary bypass impair the reticuloendothelial system?

Reticuloendothelial system (RES) function after cardiac operations is a controversial issue. Sequential changes in plasma fibronectin levels and RES phagocytic function were studied after a cardiac operation and a lung operation (control). In the cardiac operation group, the plasma fibronectin level decreased until the third postoperative day and increased thereafter. Reticuloendothelial system phagocytic function remained unchanged on the third postoperative day and then it increased. However, in the control group it increased significantly after operation. In the past, investigators have demonstrated a decline in plasma fibronectin levels following cardiac operation and have assumed that RES function was impaired. However, this sequential study showed that phagocytic function was not impaired, but its enhanced phase was delayed. Moreover, our previous morphologic studies demonstrated that RES function was potentially activated after cardiopulmonary bypass. It appears that the delay of the enhanced phase is caused by the overloading of substances which must be processed by the RES during cardiopulmonary bypass. Thus, we conclude that cardiac operation produces hyperactive, yet oversaturated RES function. There is no impairment of RES function after cardiac operations.

Oversaturation status of reticuloendothelial system following cardiopulmonary bypass

In the past, it was generally believed that the phagocytic function of the reticuloendothelial system (RES) was depressed after cardiopulmonary bypass (CPB), but several investigators reported differing results. Therefore, this study was performed to determine the effect of CPB on RES function, experimentally and clinically. Six dogs undergoing CPB (CPB group) were compared with an identical number of dogs subjected to thoracotomy without CPB (control group). A lipid emulsion test was performed in all dogs before and after the surgical procedure to measure RES phagocytic function. Any ultrastructural changes in Kupffer cells were observed by electron microscopy. In both groups, the RES phagocytic index showed a significant decline after surgery. However, comparison of the 2 groups revealed that there was a significantly greater decrease in the CPB group (p < 0.05). Electron microscopy of the Kupffer cells showed that the number of phagosomes, especially those containing deformed erythrocytes, increased after CPB. Twenty patients undergoing cardiac surgery requiring CPB (Group A) and 8 patients undergoing pulmonary resection (Group B) were studied. RES phagocytic function was determined 3 days prior to surgery and 3 days postoperatively using the lipid emulsion test. No significant difference was observed in the preoperative phagocytic indices between the 2 groups. The phagocytic function remained almost unchanged in Group A on the third postoperative day, compared with the preoperative value, but it increased significantly in Group B on the third postoperative day, compared with the preoperative value. The intergroup difference was significant on the third postoperative day (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Predictive value of skin testing, neutrophil migration and C-reactive protein for postoperative infections in cardiopulmonary bypass patients

Despite antibiotic cover for cardiac surgery the development of postoperative infection remains a feared complication. The present prospective study was designed to evaluate whether it is possible to identify preoperatively those individuals in whom the risk of a postoperative infection is significantly greater. Skin test response, chemotaxis and random migration of neutrophils, and serum levels of C-reactive protein (CRP) were chosen as indicators of host resistance. Pre-operatively and at defined postoperative time intervals, 80 patients undergoing open-heart surgery with the aid of cardiopulmonary bypass were examined. Of all the immunological variables measured in this study, the state of anergy proved the most reliable predictor of postoperative infection. Six of the nine pre-operatively anergic patients developed infections (P = 0.00026) representing one half of the postoperatively infected patients. No predictive role of CRP level or neutrophil chemotaxis can be derived from our data. The pre-operatively decreased random migration of polymorphonuclear leukocytes (PMN) from postoperatively infected patients, however, along with the significant defects in chemotactic and random PMN motility seen after cardiac surgery may partly explain the predisposition to bacterial infection in these patients. In conclusion, a pre-operative skin test makes a valuable contribution to the assessment of the patient's postoperative infectious risk.

Cardiopulmonary bypass and host defense functions in human beings: I. Serum levels and role of immunoglobulins and complement in phagocytosis

In patients undergoing open-heart surgical procedures, the serum levels of immunoglobulins and complement were determined as well as the functional capacity of these defense proteins as opsonins to facilitate phagocytosis by polymorphonuclear leukocytes. A considerable decrease in serum levels of the proteins studied was found after cardiopulmonary bypass (CPB). As a result, the opsonic capacity of post-CPB plasma was diminished. After correction for hemodilution, however, no difference between pre- and post-CPB plasma, as measured by the activity of thermolabile (e.g., complement C3) and thermostabile (e.g., immunoglobulin IgG) opsonins, could be demonstrated. It is concluded that CPB causes a quantitative but no functional decrease in levels of IgG and C3.

Depression of host-defence mechanisms following cardiac surgery

The purpose of the present study was to determine the effects of open-heart surgery on host-defence mechanisms, by studying serial changes in serum immunoglobulins, circulating lymphocyte function in patients undergoing open-heart surgery. Serum proteins and immunoglobulins were significantly depressed immediately after operation and these depressions were correlated to the degree of the durations of cardiopulmonary bypass and associated hypothermia. White cell counts in peripheral blood increased significantly after operation. In contrast, total circulating lymphocytes were depressed postoperatively. The depression of circulating lymphocytes was mainly due to a marked decrease in the number of T-cells. Mitogen responses of lymphocytes stimulated by phytohemagglutinin were also depressed postoperatively. The quantitative and qualitative depression of cell-mediated immunity following open-heart surgery was observed. However, these depressions returned to preoperative levels in one week and had no clinical significance.