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Cardiac surgery with cardiopulmonary bypass (CPB) is a recognized trigger of systemic inflammatory response, usually related to postoperative acute lung injury (ALI). As an attempt to dampen inflammatory response, steroids have been perioperatively administered to patients. Macrophage migration inhibitory factor (MIF), a regulator of the endotoxin receptor, is implicated in the pathogenesis of ALI. We have previously detected peak circulating levels of MIF, 6 hours post CPB. Experimental data have shown that steroids may induce MIF secretion by mononuclear cells. This study aims to correlate levels of MIF assayed 6 hours post CPB to the intensity of postoperative pulmonary dysfunction, analysing the impact of perioperative steroid administration.

The usual diagnostic approach to patients with sepsis in an intensive care unit (ICU) or coronary care unit is based on clinical, biochemical, microbiologic and pathologic data and on radiologic imaging (radiograph, ultrasound and computed tomography), which are used to determine the most common sites of infection. In many cases, however, the site of infection is difficult to determine. Nuclear medicine provides various noninvasive scintigraphic methods for the imaging of focal sepsis, based on the intravenous administration of a radiotracer that accumulates at the site of infection or inflammation. The combined use of total body scintigraphy with ultrasound and computed tomography is considered a useful tool for the diagnosis of occult sepsis in ICU patients, and allows the targeting of aggressive measures against infections. The aim of this study is to evaluate the diagnostic value of technetium 99 m-white blood cell (99mTc-WBC)-labeled scintigraphy and gallium-67 citrate (67Ga) scintigraphy in the detection of focal sepsis in the ICU. We reviewed seven patients affected by sepsis of unknown origin. After the usual diagnostic approach, five patients were submitted to a total body scan using the 99mTc-WBC and two patients using 67Ga. The patients had complete clinical and instrumental data, but none of the radiological image detected the site of infection. The 99mTc-WBC scan showed typical patterns of increased tracer accumulation in six different sites. Four of these sites were studied histopathologically, confirming the infection: one case of left kidney abscess was associated with concomitant infection of the psoas muscle in the same patient, one frontoparietal osteomyelitis, and one acute cholecystitis. The other two sites corresponded to pulmonary accumulation of the tracer, which was interpreted as pneumonia. Of the two patients who underwent 67Ga scintigraphy, one had decubitus ulcerated infection associated with sacrum and left femoral osteomyelitis, and the other had clinical suspect of pulmonary vasculitis and diffuse pulmonary 67Ga accumulation.

MIF was first described in the late 1960s as a T lymphocyte derived product implicated on random migration of macrophages. In the last decade it has been 'rediscovered' as a pituitary hormone as well as a macrophage product in response to stress. Experimental models have demonstrated correlation between MIF administration and inflammatory reaction. Additionally, anti-MIF treatment was associated with clear improvement of survival in certain models. As CRP, C3a and other substances with inflammatory properties, MIF has been studied specifically in the infectious setting. Results of these studies are extrapolated but not frequently applied to surgical trauma models. Trauma related to CABG in the noninfectious setting could promote sequential alterations on serum levels of CRP, C3a and MIF.