Intradialytic cerebral ischemia: Frequent, unpredictable, significant
What is the relationship between blood pressure (BP) and downstream ischemia during hemodialysis (HD)? Researchers at Oxford University Hospitals NHS Trust instigated this pilot study to investigate the relationship between BP, real-time symptoms, and cerebral oxygenation during hemodialysis. The results showed that intradialytic cerebral ischemia is a frequent occurrence that is not easily predicted from blood pressure and may be clinically significant.
The study was based on continuous BP and cerebral oxygenation measurements prospectively gathered from 635 hemodialysis sessions in 58 HD patients.
23.5 % of hemodialysis sessions featured cerebral ischemia, and a third of these cases were symptomatic (31.9 %). Episodes of hypotension were common, in 24 % of sessions the authors observed a drop of mean arterial pressure below 60 mmHg. Every 10 mmHg drop from baseline in mean arterial pressure was associated with a 3 % increase in ischemic events, and the incidence of ischemic events rose rapidly below an absolute mean arterial pressure of 60 mmHg. In spite of these associations, the authors stress that overall, BP was only poorly suited to predict downstream ischemia. And: Intradialytic cerebral ischemia, but not hypotension, correlated with decreased executive cognitive function at 12 months.
Intradialytic cerebral ischemia occurs frequently, is not easily predicted from BP and may be clinically significant for HD patients.