Surgical Tourniquets and Cerebral Emboli

BACKGROUND In 2012 76,497 primary total knee (TKR) replacements were performed in England, Wales and Northern Ireland . Traditionally TKR surgery is undertaken with the aid of a surgical tourniquet. A surgical tourniquet is an occlusive device applied around a patient's leg. The tourniquet squeezes the leg (including blood vessels within the leg) and can therefore reduce the amount of bleeding that occurs while it is inflated. An intraoperative tourniquet can therefore help to improve the surgical field of view. Although the majority of surgeons prefer to undertake TKR surgery using a tourniquet a small but increasing number are now not pursuing these devices.

There is robust evidence that the risk of deep vein thrombosis is increased if a tourniquet is used for TKR surgery. In addition embolic material in the venous system have been observed following TKR surgery and have been noted to be present in the right atrium with transoesophageal (TOE) echo intra-operatively. , Significant and potentially life threatening emboli have been documented to enter the cerebral circulation via pulmonary arterio-venous shunts and patent foramen ovale (PFO) (27% of patients at autopsy) , . The clinical manifestations of cerebral emboli post tourniquet deflation in TKR are not fully understood. Fat embolism syndrome and post-operative confusion in TKR patients may be the result of emboli formed during a TKR. ,

AIM

• Is there evidence of emboli entering the cerebral circulation following tourniquet deflation in TKR surgery?
• Is there evidence of MRI detectable brain lesions and or any clinical change in cognition compared in patients undergoing TKR surgery with a tourniquet compared to those that do not have a tourniquet?