Value of postoperative C-reactive protein and leukocyte count after elective thoracoabdominal aneurysm surgery

Introduction

There are many causes for a systemic inflammatory response after thoracoabdominal aortic aneurysm (TAAA) repair. The aneurysm itself, the surgical trauma, ischemia-reperfusion injury and reactions to graft material can all cause an inflammatory response. This makes it difficult to identify postoperative infection. A PubMed search revealed no study on how to discern between normal postoperative levels of inflammation and postoperative infection after TAAA repair.

Methods

In this prospective single-centre study we included 34 patients. They underwent elective surgical TAAA repair. Immunocompromised patients and patients using immunosuppressive agents were excluded. C-reactive protein (CRP) levels and leukocyte count were measured in the operating room and on every postoperative day until discharge from the ICU, with a maximum of 14 days. We also determined the occurrence of fever.

Results

Five patients (15%) suffered a postoperative infection: three pulmonary infections, one bacteraemia of unknown origin and one patient suffered a septic period without positive cultures. In all patients there was a postoperative rise in CRP with a maximum on the second and third postoperative day. The median CRP was 229 mg/l on the second day and 221 mg/l on the third postoperative day. CRP declined towards preoperative levels during the first 2 weeks after surgery. The leukocyte count continued to rise postoperatively to 13 × 10⁹/l on day 14. There was no correlation between fever or leukocyte count and infection. In only three of five patients with postoperative infection was a second rise in CRP noted.

Conclusion

This study shows the CRP levels and leukocyte count that can be expected in the ICU after TAAA surgery. Surprisingly the leukocyte count continued to rise. This may be caused by the fact that patients with infection tend to stay longer in the ICU. The median CRP level on day 14, however, was only 22 mg/l. Not all postoperative infections caused a rise in the already high CRP levels. So in some cases CRP, leukocyte and temperature may be of no clinical value. Clinical evaluation combined with positive cultures may be the only method to diagnose postoperative infection in this group of patients.