A single blinded randomised, crossover, individual comparison on cardiac performance of xenon vs. sevoflurane inhalation in humans undergoing coronary artery bypass grafting

In 1951 the first results were published about the use of xenon as an
anaesthetic agent in humans undergoing surgery. Over the years many papers were
published, which covered several aspects of the properties of xenon in
anaesthesiology. It is frequently claimed that xenon is an ideal anaesthetic
agent as it is inflammable, with low toxicity, and devoid of teratogenic
effects. Moreover, induction and recovery are rapid and consequently permit
good anaesthetic control. Xenon is registered as a medical gas in the European
Community since April 2007.
Over the last years, papers are being published reporting that xenon has
relatively few, minor side effects. From our own study group a case report
about the use of xenon for Eisenmenger*s Syndrome was published to illustrate
its cardiovascular stability.
Recently, our study group has participated also in two multi-centre trials in
which xenon was used as an anaesthetic agent and compared to isoflurane
anaesthesia. The first study evaluated the efficacy and safety of xenon
inhalation in patients who had to undergo elective surgery. In the second study
cardiac performance was studied using a transoesophageal echocardiography (TEE)
after inhalation of xenon in patients without cardiopulmonary disease scheduled
for elective general surgery. Cardio depressive effects were observed after
isoflurane anaesthesia, whereas the occurrence of haemodynamic side effects was
diminished during xenon anaesthesia. From these results, it has been suggested
that the administration of xenon could be a therapeutic option when given to
cardiac risk patients. Therefore, we like to study the effect of xenon
inhalation on the cardiac performance in patients scheduled for elective
coronary artery bypass grafting (CABG).

The aim of this study is to evaluate the immediate effect of xenon inhalation
on cardiac performance in patients scheduled for CABG surgery in comparison
with the effect induced by sevoflurane inhalation.

This study is designed as a single-blinded, prospective, single-centre,
crossover, and randomised, controlled clinical study. The total number of
patients enrolled will be 20.

Patients in Group A will at first receive 1 MAC Sevoflurane in O2/Air, followed
after a 20-min period by measuring the contractility index using TOE. Then,
Sevoflurane will be washed out and 65% xenon (together with O2) will be washed
in, followed again after a 20-min period with measurement of contractility
index by using TOE. Thereafter xenon will also be washed out.
Patients in Group B will be examined in the same way, however, the sequence of
the drugs is opposit, thus at first, wash-in of xenon and after washout
followed by washin and washout of sevoflurane.

Patients will come to operating theatre 1 hour prior to surgery to receive
general anesthesia. In this hour we will look at the contractility of the heart
with TEE.