P Giomarelli

Reduction of oxidative stress does not affect recovery of myocardial function: warm continuous versus cold intermittent blood cardioplegia.

OBJECTIVE: To compare oxidative stress after cardiac surgery in patients treated with two different methods of myocardial protection: warm continuous versus cold intermittent blood cardioplegia. To correlate oxidative stress with postoperative myocardial dysfunction. DESIGN: Prospective, randomised, double blind, trial. SETTING: Institutional centre of cardiovascular surgery. PATIENTS: 20 patients were selected for coronary artery bypass surgery (CABG) on the following basis: stable angina, ejection fraction > 50%, double or triple vessel disease, no previous CABG or associated disease. Patients were randomised to two groups of 10 patients each. INTERVENTIONS: Patients underwent CABG with one of two different methods of myocardial protection and cardiopulmonary bypass. CBC group: intermittent cold blood antegrade-retrograde cardioplegia with moderate hypothermic cardiopulmonary bypass; WBC group: continuous warm blood antegrade-retrograde cardioplegia with mild hypothermic cardiopulmonary bypass. MAIN OUTCOME MEASURE: The index of oxidative stress used was the alteration of whole blood and plasma glutathione redox status. Samples were collected from the coronary sinus and peripheral vein before anaesthesia (T1), before aortic unclamping (T2), 15 minutes (T3), and 30 minutes (T4) after unclamping. Haemodynamic parameters were measured with thermodilution techniques. RESULTS: Oxidised glutathione and glutathione-cysteine mixed disulphide significantly increased in the coronary sinus plasma in the CBC group, and the overall redox balance of glutathione was decreased (P < 0.01) at T2-T4 versus T1, and compared with the WBC group. Comparable results were obtained for coronary sinus blood. There was no correlation between postoperative haemodynamic measurements and oxidative stress markers. CONCLUSIONS: Oxidative stress was significant in patients undergoing CABG using cold blood cardioplegia, while the warm technique minimised the effects of ischaemia. However, oxidative stress was not correlated with myocardial dysfunction following CABG.

Heparin coating of extracorporeal circuits inhibits cytokine release from mononuclear cells during cardiac operations.

Purpose To evalute whether the production of interleukin 2 (IL 2), interlukin 6 (IL 6) and interlukin 10 (IL 10) from stimulated peripheal blood mononuclear cells (PBMC) was affected by coating extracorporeal circuits in patients undergoing cardiopulmonary bypass (CPB). In addition, postoperative clinical parameters were compared between patients with heparin-coated and uncoated CPB. Design Prospective, controlled in vivo/ex vivo study. Procedure Blood samples were drawn immediately before, at the end and 24 hours after the end of CPB using either a conventional circuit (n=10) or a heparin-coated circuit (n=10) in patients undergoing CPB. Cytokine release on the supernatants of activated PBMC was detected. Cardiopulmonary parameters were measured before CPB, at ICU admission, 3 hours and 24 hours after ICU admission in both groups of patients. Statistical difference intragroups and between groups were investigated with the analysis of variance for repeated measures. Results IL 6 and IL 10 release was significantly less (p<0.05) in the heparin-coated group. No differences in clinical parameters were observed between the two groups. Conclusions These results suggest that with the use of heparin-coated circuits there is a lower production of IL 6 and IL 10 from isolated PBMC than with uncoated circuits.

Respiratory Function in CAPD

Respiratory function was studied in 15 CAPD patients with indwelling dialysate and in 10 patients before and after hemodialysis. Respiratory volumes and flow rates were normal in CAPD patients but oscillated with hemodialysis. CAPD was characterized by hyperventilation and increased O2 consumption while hemodialysis induced a restrictive defect attributed to pulmonary leukocyte sequestration. A modest restrictive defect in CAPD patients may relate to the intraabdominal fluid volume.