Background: Confusion occurs in up to 60% of patients following neck of femur fracture, delaying hospital discharge. We investigated venous – arterial circulation shunts (v-aCS) and the influence of cerebral embolism before and during surgery on subsequent cognitive function.

Methods: Cerebral emboli were counted in 16 patients with an inter-trochanteric or Garden III/IV fracture by transcranial Doppler (TCD) monitoring over 1 hour pre-operatively and intra-operatively. A v-aCS was diagnosed when 1 or more microbubbles were detected in the middle cerebral artery by TCD following intravenous injection of a microbubble emulsion. Cognitive function was investigated by a battery of computerised tests preoperatively and at 5 days postoperatively.

Results: Cerebral emboli were detected in 9 of 16 patients preoperatively (median 2, range 1–23) and in 10 patients during surgery (median 10, range 4 – 617). A v-aCS was associated with preoperative emboli in 9 patients (p=0.036, Fisher’s Exact) and intraoperative emboli in 10 patients (p=0.011, Fisher’s Exact). Cognitive function deteriorated following surgery only in patients with emboli, with the median (range) overall reaction times increasing from 3220ms (1926–5868) to 7493ms (4690–15992) [p=0.008]. The overall accuracy deteriorated from 2.57 to 2.37 (NS).

Conclusion: Cerebral embolism is common following femoral neck fracture in patients with a v-aCS and was associated with a deterioration in cognitive function.

Background: Cerebral emboli may be detected by transcranial Doppler (TCD) in patients undergoing hip arthroplasty. Venous – arterial circulation shunts (v-aCS), cerebral embolism and postoperative organ dysfunction were investigated in elective hip arthroplasty.

Methods: TCD was used to identify v-aCS in (i) elective hip arthroplasty (n=45), (ii) abdominal aortic aneurysm surgery (AAA) (n=20) and (iii) transurethral resection of prostate (TURP) (n=10). A v-aCS was diagnosed when 1 or more microbubbles were detected in the middle cerebral artery by TCD following intravenous injection of a microbubble emulsion. TCD was also used to monitor for intraoperative cerebral emboli (ICE). Cognitive function was measured by a battery of computerised tests before and 5 days after surgery. Troponin T, AST, ALP, Bilirubin, Creatinine, Urea and Creatinine clearance were measured pre-operatively and 24 and 48 hours post-operatively.

Results: Cerebral embolism occurred in 26 of 45 patients during hip arthroplasty (median 4, range 1 – 368) but not during AAA or TURP surgery. Cerebral embolism only occurred in patients with a v-aCS (p< 0.001) and was strongly associated with the size of the v-aCS (rs=0.8, p< 0.001). The number of ICE had no influence on Troponin T, renal function, liver function or cognitive function.

Conclusion: Cerebral embolism is common in patients with a v-aCS during hip arthroplasty. There was no evidence of cerebral or multi-organ damage due to paradoxical embolism.

Fat embolism occurs following fractures of a long bone or arthroplasty. We investigated whether paradoxical embolisation through a venous-to-arterial circulation shunt (v-a) could lead to cerebral embolisation during elective hip or knee arthroplasty.

Transcranial Doppler ultrasound (TCD), following the intravenous injection of microbubble contrast, identified the presence of a shunt in 41 patients undergoing hip (n=20) or knee (n=21) arthroplasty. Intra-operative cerebral embolism was detected during continuous TCD monitoring. Of the 41 patients, 34 had a v-a shunt of whom 18 had an embolism and embolism only occurred in patients with a shunt (p = 0.012). Spontaneous and larger shunts were associated with a greater number of emboli (r_s = 0.67 and r_s = 0.71 respectively, p < 0.01). Observations in two patients with large spontaneous shunts revealed 368 and 203 emboli and unexplained post-operative confusion and pancreatitis.

Paradoxical cerebral embolisation only occurred in patients with a shunt and may explain both postoperative confusion and fat embolism syndrome following surgery.