Endotoxemia and mediator release during cardiac surgery.

Endotoxemia in man is a controversial issue. However, endotoxin is a potent trigger of the inflammatory response. Therefore, endotoxin translocation and mediator release was investigated in patients undergoing cardiac surgery. In 40 patients (13 women and 27 men, ages ranging from 30 to 73 years with a median of 60 years), plasma concentrations of endotoxin, interleukin-6 (IL-6), and C-reactive protein (CRP) were determined during and after cardiovascular bypass. In a subgroup of 10 patients, myeloid-related proteins: MRP8, MRP14, and the soluble heterocomplex (MRP8/MRP14) levels were additionally studied. A significant increase (p < 0.01) of plasma endotoxin concentrations was found during surgery, culminating in a peak (median value of 0.82 EU/mL) during reperfusion. Plasma levels of endotoxin continued to be slightly raised until the 5th postoperative day, whereas those of interleukin-6 rose at the end of the operation and were at their highest level 6 hours postoperatively (median value of 218 pg/mL). CRP levels were increased 24 hours postoperatively with a median value of 114 mg/L and peaked on day 2 (191 mg/L). A statistically significant correlation between the intraoperative endotoxin plasma concentrations and IL-6 concentrations was established (p < 0.05). The MRP8/MRP14 heterocomplex increased until day 2 after surgery, except MRP14, which showed the highest level at day 1 (55 ng/mL). Cardiac surgery is associated with endotoxemia and a marked acute-phase response. Therefore, endotoxin must be regarded as a pathophysiologic mediator. The role of the gut as a source of endotoxemia following cardiac surgery deserves further attention.