Surgical Tourniquets and Cerebral Emboli

Study Overview
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Brief Summary
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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?

Official Title
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Surgical Tourniquets and Cerebral Emboli Pilot Study

Conditions
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Osteoarthritis, RA, Trauma

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: i.Aged >18 ii.Undergoing elective TKR iii.Able to give written informed consent iv.No contraindications to MR imaging Exclusion Criteria: i. Ages <16 ii. Not able to give written informed consent iv. Contraindications to MR imaging

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Total knee replacement patients<br>Patients who are due to have a total knee replacement will be studied to look for the presence of Emboli. Observational with imaging. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Emboli on Transcranial Doppler | 2 independent technicians will verify the number of emboli detected. Non-invasive | Intra-operative | 
| MRI brain scan - presence of Emboli | Reviewed by Professor of radiology - presence, number and volume of diffusion weighted lesions | Post-operatively, prior to discharge | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mini-mental state examination | Set of 30 questions which test cognitive function | Pre-operative vs Post-operative |