Heart surgery is known to cause damage to the inner lining of blood vessels called the “endothelial glycocalyx”. This damage can affect bleeding, swelling and inflammation which can harm organs and delay recovery after surgery. Damage to this layer can be measured using special blood tests.

Currently there are no drugs used to protect this layer during surgery. Some experiments have shown the commonly used local anaesthetic “lidocaine” and the antibiotic “doxycycline” may be of benefit to protect this layer.

In this study, patients undergoing heart surgery are randomly allocated to receive one or other of the medicines or neither (a “control” group). Blood tests will indicate if these medicines have an effect on this layer. We hypothesise that lidocaine and or doxycycline may protect the endothelial glycocalyx during heart surgery.

Should these therapies show improvements in the blood tests; we would then expand our work to look at differences including quality of recovery from heart surgery which could make a real difference to patients undergoing cardiac and other major surgeries.