Hypothermic versus normothermic cardiopulmonary bypass in patients with valvular heart disease.

OBJECTIVE: The aim of this study was to test the hypothesis that normothermic cardiopulmonary bypass (CPB) is as effective as hypothermic CPB in terms of cardiac protection (cTnI level) and outcome in patients with valvular heart disease. DESIGN: Prospective randomized study. SETTING: A tertiary cardiothoracic referral center. PARTICIPANTS: 140 patients who had valvular heart disease, with/without coronary artery disease, surgically treated under CPB. INTERVENTIONS: The patients were allocated randomly to undergo either hypothermic (temperature [T], 31 °C-32 °C) or normothermic CPB (T>36 °C). MEASUREMENTS AND MAIN RESULTS: The primary endpoint was the dynamics of troponin I. The secondary endpoints were ventilation time, the need for inotropic support, intensive care unit (ICU) and hospital stay durations, complications, and mortality. There were no significant intergroup differences in dynamics of troponin I. Ventilation time was significantly lower in the hypothermic group (6 (5-9) and 8 (5-12); p = 0.01). CONCLUSIONS: Normothermic CPB in patients with valvular heart disease was as effective as hypothermic perfusion in terms of myocardial protection after the surgery assessed by cTnI release. The short ventilation duration in patients who underwent hypothermic CPB needs to be confirmed in a future investigation.

Does glutamine promote benefits for patients with diabetes mellitus scheduled for cardiac surgery?

BACKGROUND: We hypothesised, that perioperative use of N(2)-L-alanyl-L-glutamine confers cardioprotection and improves insulin resistance in diabetic patients with coronary artery disease operated under cardiopulmonary bypass. METHODS: This double-blind, placebo-controlled, randomised study included 64 patients with diabetes mellitus type 2 who were scheduled for on-pump coronary artery bypass graft surgery. The protocol group (32 patients) and the control group (32 patients) glutamine (0.4 g/kg/day of 20% solution of N(2)-L-alanyl-L-glutamine ("Dipeptiven(®)" Fresenius Kabi, Germany)) and placebo (0.9% NaCl), respectively. Perioperative concentration of troponin I in plasma was considered as the primary end-point. Whereas the secondary end-points were insulin resistance, insulin sensitivity, ß-cell function, blood glucose, plasma triglycerides and free fatty acids concentrations. Insulin resistance, insulin sensitivity and ß-cell function were measured using HOMA equation. Thermodilution method was used to measure haemodynamics in all the patients. RESULTS: No differences have been found in perioperative dynamics of troponin I, insulin resistance, insulin sensitivity, ß-cell function, blood glucose, plasma triglycerides free fatty acids concentrations and haemodynamics. CONCLUSION: Our results have failed to confirm the cardioprotective properties and modulatory effect on perioperative insulin resistance that are thought to be attributable to parenteral glutamine administration in dose 0.4 g/kg/day among cardiac patients with DM operated on under CPB.

Glutamine is cardioprotective in patients with ischemic heart disease following cardiopulmonary bypass.

BACKGROUND: The aim of the present study was to investigate the cardioprotective effects of the perioperative use of N(2)-L-alanyl-L-glutamine (GLN) in patients with ischemic heart disease (IHD) who undergo their operations under cardiopulmonary bypass (CPB). METHODS: This double-blind, placebo-controlled, randomized study included 50 patients who underwent cardiac surgery with CPB. Exclusion criteria were a left ventricular ejection fraction <50%, diabetes mellitus, <3 months since the onset of myocardial infarction, and emergency surgery. Patients in the study group (n = 25) received 0.4 g/kg GLN (Dipeptiven, 20% solution) per day. Patients in the control group (n = 25) were administered a placebo (0.9% NaCl). The primary end point was the dynamics of troponin I at the following stages: (1) prior to anesthesia, (2) 30 minutes after CPB, (3) 6 hours after CPB, (4) 24 hours after surgery, and (5) 48 hours after surgery. Secondary end points included measurements of hemodynamics with a Swan-Ganz catheter. RESULTS: On the first postoperative day after the surgery, the median troponin I level was significantly lower in the study group than in the placebo group: 1.280 ng/mL (interquartile range [IQR], 0.840-2.230 ng/mL) versus 2.410 ng/mL (IQR, 1.060-6.600 ng/mL) (P = .035). At 4 hours after cardiopulmonary bypass (CPB), the median cardiac index was higher in the patients in the study group: 2.58 L/min per m2 (IQR, 2.34-2.91 L/min per m2) versus 2.03 L/min per m2 (IQR, 1.76-2.32 L/min per m2) (P = .002). The median stroke index also was higher in the patients who received GLN: 32.8 mL/m2 (IQR, 27.8-36.0 mL/m2) versus 26.1 mL/m2 (IQR, 22.6-31.8 mL/m2) (P = .023). The median systemic vascular resistance index was significantly lower in the study group than in the placebo group: 1942 dyn·s/cm5 per m2 (IQR, 1828-2209 dyn·s/cm5 per m2) versus 2456 dyn·s/cm5 per m2 (IQR, 2400-3265 dyn·s/cm5 per m2) (P = .001). CONCLUSION: Perioperative administration of GLN during the first 24 hours has cardioprotective effects in IHD patients following CPB. This technique enhances the troponin concentration at 24 hours after surgery and is associated with improved myocardial function.