SURGICAL TOURNIQUET AND CEREBRAL EMBOLI: AN EXPLORATORY OBSERVATIONAL STUDY

Background Traditionally, a Surgical Tourniquet (ST) is used during Total Knee Replacement Surgery (TKRS) to prevent blood flow to the leg and improve the surgical field of view. The use of a ST is known to increase the risk of venous thromboembolism. Echogenic material, suggestive of emboli has been observed in the brain following ST deflation in TKRS despite the absence of a patent foramen ovale, likely through pulmonary shunts. The aim of this study was to assess whether cerebral emboli result from tourniquet use in TKRS and the sequelae of any emboli. Methods 11 subjects from a single centre undergoing routine TKRS with a ST gave informed consent. Each participant had diffusion weighted MR brain imaging prior to, and within 48 hours after TKRS and completed pre and post-operative mini-mental state examinations (MMSE). Results Pre and post-operative MR imaging were assessed by a senior radiologist and the results were reported according to Age and Cognitive Performance Research Centre (ACPRC) rating scale. There were no changes from pre and post-operative MR scans. 4 participants (36%) had no change in MMSE scores. These participants had a score of 1 or 0 in both MR scans. 7 participants (63%) had a score of 2 or 3. These participants had mean 2.8 point (9.5%) drop on MMSE (IQR = 1) within 48 hours. Conclusions In this small, exploratory study we found no evidence of discrete cerebral emboli occurring with the use of ST in TKRS. Interestingly, participants noted to have minimal or no pre-operative ischaemic change appeared to maintain more cognitive function post-operatively than those with higher levels of pre-existing ischaemia. Subtle changes in ischaemic load in patients with pre-existing ischaemia may lead to impaired cognitive function, however further evidence is required to confirm this theory. Level of Evidence III Approval Protocol approved by NRES Committee Yorkshire & The Humber, Leeds West and The Research, Development & Innovation Department University Hospitals Coventry & Warwickshire