Helium and organ protection during bypass surgery

The aim of this clinical study is to investigate whether the non-anaesthetic noble gas helium induces preconditioning (PreC) and postconditioning (PostC) in patients undergoing coronary artery bypass graft (CABG) surgery.
Primary endpoinst are detection of signalling pathway molecules (PKC-e, p38MAPK, ERK and HSP27) and secondary parameters include estimation of myocardial damage by measurement of cardiac enzymes.

Recent experimental and clinical data showed that the noble gas helium protects against myocardial reperfusion injury in rabbits in vivo and induces late preconditioning in rat hearts. It has also been demonstrated that another noble gas, xenon, can protect from myocardial damage by postconditioning. Supported by this evidence we hypothesize that helium induces pre- and postconditioning in humans.

Tissue samples for investigation of primary outcome will be taken during surgery, first and second sample will be taken during installation of cardiopulmonary bypass, third sample will be taken after weaning of cardiopulmonary bypass, when aorta cross clamp is taken off.

Bood samples for investigations of secondary outcomes will be taken at baseline (before surgery),4,12,24 and 48 hours after surgery.

Hemodynamic parameters will be obtained during surgery.

First group of patients will receive 3 * 5 minutes of Helium just before aortic cross clamping (preconditioning, PreC,)

second group will receive helium 3*5 min just before release of the aortic cross clamp (Postconditioning, PostC,)

Third group will receive both regimens (pre and postconditioning, PrePostC,).

Fourth group of patients will serve as untreated controls (CON,)

Fifth group will serve as positive controls, and receive preconditioning with sevoflurane (3 * 5min) before aortic cross clamping (anaesthetic preconditioning, APC,)