Perioperative inflammation and hypotension

Despite advances in surgical and anesthetic techniques in the past decades, complications are common after major surgery. The negative impact of postoperative complications on outcome is of significant concern to patients and their clinicians. The pathophysiological mechanisms of complications after surgery, however, are largely unknown. This thesis described the relation between two possible determinants of adverse events after major surgery: perioperative inflammation and hypotension. The association of systemic inflammation and outcome was assessed in major abdominal and cardiac surgery. The development of the systemic inflammatory response syndrome (SIRS) in 121 patients undergoing transapical transcatheter aortic valve implantation (TAVI) was associated with an independently increased risk of any adverse event (adjusted odds ratio (AOR) 4.0, 95% confidence interval (CI); 1.6 - 9.6). In a subsequent exploratory analysis, an association between perioperative tissue hypoperfusion (a potential cause of tissue/reperfusion injury) and SIRS was not observed. In 135 patients undergoing major abdominal surgery, an interleukin-6 (IL-6) level of >432 pg/ml was an independent predictor of postoperative complications (AOR 3.3, 95% CI; 1.3 – 8.5). The diagnostic accuracy of IL-6 on day one (area under the curve (AUC) 0.67) was comparable to the diagnostic accuracy of CRP on day three (AUC 0.73). In patients undergoing cardiac surgery preoperative statin therapy was associated with a 67% reduced risk of infectious complications (AOR 0.3, 95% CI; 0.2 - 0.6). The association of intraoperative hypotension (IOH) and postoperative renal function was studied in patients undergoing major abdominal surgery and coronary artery bypass grafting (CABG). None of the investigated IOH definitions (i.e. several absolute and relative mean arterial pressure (MAP) thresholds and the AUC below several absolute MAP thresholds) were associated with a change in the estimated glomerular filtration rate (eGFR) after major abdominal surgery. In patients undergoing CABG none of the IOH definitions investigated were associated with AKI. In conclusion, perioperative systemic inflammation after major surgery is commonly observed an important factor in the development of adverse outcome. Perioperative inflammation may be used as a predictive marker for postoperative complications. In addition, it can be used as a therapeutic target for improving outcome. The role of IOH in the development of AKI after major surgery seems limited.