Interleukin-6 predicts inflammation-induced increase of Glucagon-like peptide-1 in humans in response to cardiac surgery with association to parameters of glucose metabolism.

OBJECTIVE: Glucagon-like peptide-1 (GLP-1) is an incretin hormone, which gets secreted in response to nutritional stimuli from the gut mediating glucose-dependent insulin secretion. Interestingly, GLP-1 was recently found to be also increased in response to inflammatory stimuli in an interleukin 6 (IL-6) dependent manner in mice. The relevance of this finding to humans is unknown but has been suggested by the presence of high circulating GLP-1 levels in critically ill patients that correlated with markers of inflammation. This study was performed to elucidate, whether a direct link exists between inflammation and GLP-1 secretion in humans. RESEARCH DESIGN AND METHODS: We enrolled 22 non-diabetic patients scheduled for cardiac surgery as a reproducible inflammatory stimulus with repeated blood sampling before and after surgery. RESULTS: Mean total circulating GLP-1 levels significantly increased in response to surgery from 25.5 ± 15.6 pM to 51.9 ± 42.7 pM which was not found in a control population. This was preceded by an early rise of IL6, which was significantly associated with GLP-1 under inflammatory but not basal conditions. Using repeated measure ANCOVA, IL6 best predicted the observed kinetics of GLP-1, followed by blood glucose concentrations and cortisol plasma levels. Furthermore, GLP-1 plasma concentrations significantly predicted endogenous insulin production as assessed by C-peptide concentrations over time, while an inverse association was found for insulin infusion rate. CONCLUSION: We found GLP-1 secretion to be increased in response to inflammatory stimuli in humans, which was associated to parameters of glucose metabolism and best predicted by IL6.

Noninvasive mechanical ventilation in patients with acute respiratory failure after cardiac surgery.

OBJECTIVE: To evaluate the feasibility and outcomes of protocol-driven noninvasive mechanical ventilation in patients with acute respiratory failure (ARF) after cardiac surgery. METHODS: From 2001 to 2004, a total of 2428 cardiac surgery patients admitted to our intensive care unit were observed. After exclusion of patients who received tracheostomy or were discharged while still on mechanical ventilation, 2261 patients with spontaneous breathing were further evaluated for ARF. Patients diagnosed with ARF were treated with intermittent noninvasive mechanical ventilation (NIV) if possible. Risk factors for the development of postoperative ARF as well as outcomes in patients with and without ARF were analyzed. RESULTS: In 2261 spontaneously breathing postoperative cardiac surgical patients after primarily successful extubation, 799 patients (35%) were diagnosed with ARF. Fifty-six patients (7%) did not tolerate NIV treatment. In 743 patients (33%) intermittent NIV was performed. In patients with ARF, ejection fraction was lower, combined cardiac surgical procedures were more frequent, postoperative mechanical ventilation time was longer, and the severity of illness score (SAPS II) was higher (P < .05). The duration of catecholamine support was longer, and the transfusion rate was higher in the NIV group (P < .05); however, mortality did not differ between patients with ARF treated by NIV and patients without ARF. CONCLUSION: Our study demonstrates the feasibility of NIV in patients after cardiac surgery. These results might suggest that NIV should be considered as first-line ventilatory support in ARF after cardiac surgery. A large randomized trial is warranted to confirm these findings.

Serum concentrations of cortisol, interleukin 6, leptin and adiponectin predict stress induced insulin resistance in acute inflammatory reactions.

INTRODUCTION: Inflammatory stimuli are causative for insulin resistance in obesity as well as in acute inflammatory reactions. Ongoing research has identified a variety of secreted proteins that are released from immune cells and adipocytes as mediators of insulin resistance; however, knowledge about their relevance for acute inflammatory insulin resistance remains limited. In this study we aimed for a clarification of the relevance of different insulin resistance mediating factors in an acute inflammatory situation. METHODS: Insulin resistance was measured in a cohort of 37 non-diabetic patients undergoing cardiac surgery by assessment of insulin requirement to maintain euglycaemia and repeated measurements of an insulin glycaemic index. The kinetics of cortisol, interleukin 6 (IL6), tumour necrosis factor alpha (TNFalpha), resistin, leptin and adiponectin were assessed by repeated measurements in a period of 48 h. RESULTS: Insulin resistance increased during the observation period and peaked 22 h after the beginning of the operation. IL6 and TNFalpha displayed an early increase with peak concentrations at the 4-h time point. Serum levels of cortisol, resistin and leptin increased more slowly and peaked at the 22-h time point, while adiponectin declined, reaching a base at the 22-h time point. Model assessment identified cortisol as the best predictor of insulin resistance, followed by IL6, leptin and adiponectin. No additional information was gained by modelling for TNFalpha, resistin, catecholamine infusion rate, sex, age, body mass index (BMI), operation time or medication. CONCLUSIONS: Serum cortisol levels are the best predictor for inflammatory insulin resistance followed by IL6, leptin and adiponectin. TNFalpha, and resistin have minor relevance as predictors of stress dependent insulin resistance.

Indocyanine green clearance as an outcome prediction tool in cardiac surgery: a prospective study.

PURPOSE: To evaluate the role of plasma disappearance rate of indocyanine green (PDR-ICG) as an outcome prediction tool in cardiac surgery. PATIENTS AND METHODS: One hundred ninety patients undergoing coronary artery bypass grafting, valve surgery or combined procedures were enrolled. PDR-ICG measurements along with standard lab values were performed preoperative and on postoperative days 1, 2, and on discharge from the intensive care unit. Adverse outcomes were defined as prolonged length of stay in the intensive care unit and/or mortality. Two groups were defined according to length of stay in the intensive care unit (≤ 3 days vs >3 days). RESULTS: PDR-ICG values differed significantly for all time points between the groups. In a multivariate model, in patients over 65 years with a EuroSCORE below 8.5, a preoperative PDR-ICG value below 12.85%/min was the strongest independent predictor for prolonged intensive care unit stay (>3 days). A preoperative PDR-ICG value below 8.2%/min was the strongest independent predictor for mortality in a multivariate analysis including age, cardiac function, and EuroSCORE. CONCLUSIONS: In addition to the established scores, PDR-ICG may provide valuable information for the assessment of perioperative morbidity and mortality in cardiac surgery. Pre- and early postoperative measurements may help to identify patients at risk for developing perioperative complications.