Cardiac Bypass Surgery in Adult Patients 65 Years and Older, Postoperative Cognitive Dysfunction, Postoperative Delirium
Conditions
Keywords
Postoperative cognitive dysfunction, Coronary artery bypass graft surgery, Postoperative cognitive improvement, Postoperative delirium
Brief summary
Post-Operative Cognitive Decline (POCD) is common after cardiac surgery and associated with increased morbidity and mortality. The pathophysiology of POCD is only poorly understood. Causes include hypoperfusion, microemboli and the systemic inflammatory response, which result in a reduction of cerebral oxygen delivery. Cerebral oxygenation can be monitored non-invasively by measuring frontal lobe oxygen saturation (rSO2). The bispectral index (BIS) of the electroencephalogram is widely known to measure depth of anaesthesia, and there is a high correlation between BIS, a dimensionless calculated number between 0 and 100, and clinical criteria of sedation. With BIS below 60 recall is extremely low. The investigators demonstrated recently that inappropriately high levels of anaesthesia may be associated with poorer long-term outcomes in cognition after non-cardiac surgery (Ballard et al. 2012). Whether optimisation of the depth of anaesthesia and cerebral oxygenation has an effect on postoperative cognitive function in patients undergoing cardiac surgery is unknown. The investigators hypothesize that the incidence of POCD in elderly patients (\> 65 years old) at 6 weeks is less with mildly deep anaesthesia (BIS 50 +- 10) and optimised rSO2 (interventions when rSO2 drops below 15% of baseline reading) when compared with current practice (BIS blinded anaesthesia, reflecting moderately to highly deep anaesthesia and blinded rSO2 measurements).
Interventions
OTHERTargeted intra-operative depth of anaesthesia
The intervention group receives isoflurane at a concentration that results in a BIS value between 40-60 intra-operatively.
Sponsors
King's College Hospital NHS Trust
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
65 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* patients undergoing elective coronary artery bypass graft surgery * patients at 65 years of age and older
Exclusion criteria
* diseases of the central nervous system including dementia * inadequate knowledge of English * a current or past psychiatric illness * current use of tranquilizers or antidepressants * severe visual, auditory, or motor handicap
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Incidence of postoperative cognitive decline after bypass surgery | Six weeks after bypass surgery |
Secondary
| Measure | Time frame |
|---|---|
| Incidence of postoperative cognitive decline 5 days and 1 year after bypass surgery | Five days and one year postoperatively |
| Difference in degree of postoperative cognitive decline at 5 days, 6 weeks or 1 year after bypass surgery | 5days, 6 weeks or 1 year postoperatively |
| Postoperative Delirium | 3-5 days postoperatively |
| Postoperative central nervous system and myocardial biochemical markers | up to 48 hours postoperatively |
Countries
United Kingdom
Outcome results
None listed