O1061 INTRAOPERATIVE CEREBRAL MICROEMBOLI ASSAY DURING HIP AND KNEE ARTHROPLASTY

Abstract

Aims: To compare the intraoperative cerebral microemboli load between primary total hip (THA) and knee arthroplsty (TKA) using transcranial Doppler ultrasound and to investigate whether a patent foramen ovale influences cerebral embolic load in general. The timing of the microemboli will be related to certain surgical activities to determine if a specific relationship exists. Methods: Patients undergoing primary TKA or THA, with no history of stroke, TIA, ongoing CNS disease or alcoholism included. All operations carried out under a standardised general anaesthetic and performed by two consultant orthopaedic surgeons. Microemboli load recorded, using transcranial Doppler ultrasound (TCD), onto VHS tape for subsequent playback and analysis. Patent foramen ovale detection performed using bolus intravenous injection of agitated saline followed by valsalva manoeuvre technique and TCD. Timing of specific surgical steps recorded for each operation and emboli load calculated for that period. Results: 20 THA and 20 TKA patients were studied. Cerebral microembolisation occurred in 50% of THA and 40% of TKA patients. Total microembolic load for THA patients was 137 (range=0–83) and 50 (range=0–21) for TKA patients. Prevalence of PFO in the THA group was 35%, and 20% in the TKA group. 57.1% of PFO positive THA patients and 75% of PFO positive TKA patients displayed microemboli. Insertion of the femoral component in THA and release of the tourniquet in TKA were associated with higher cerebral microemboli load. Conclusion: Intraoperative cerebral microembolisation occurs in almost half of patients during hip and knee arthroplasty. Patients who have a PFO appear more likely to be associated with cerebral embolisation. Specific surgical activities are associated with larger embolic loads.