None listed
Conditions
Brief summary
Recently five overseas studies have found an association between deep anaesthesia and subsequent mortality within one year. There is a need for a large prospective randomised trial of "deep" versus "light" anaesthesia to determine if the relationship is a causal one. This would require the study of about 6000 patients. In this pilot study, 100 patients will be randomised to either "light" or "deep" anaesthesia using the Bispectral Index depth monitor. In all other respects the anaesthesia will be unaltered in choice of anaesthetic drugs or techniques used. We will then follow up all patients for one year to ascertain the incidence of complications of anaesthesia and surgery, cancer recurrence if relevant and survival. The study has the support of the Clinical Trials group of the Australian and New Zealand College of Anaesthetists. If successful, the pilot study will be used as the basis for a large project grant to the Health Research Council in New Zealand (NZ), hopefully combined with an application to the National Health and Medical Research Council in Australia.
Interventions
Intervention General anaesthesia monitored with bispectral index (BIS) or spectral entropy (SE). Targets in the two groups will be BIS (or SE) 50 and 35. We expect 95% of anaesthesia time to be within 5 units of the target range, and no deviations to be greater than 5 minutes. Maintenance phase will be from ten minutes after induction until switching off volatile or hypnotic at the end of the operation.
Anaesthesia Standard care using standard anaesthetic hypnotics, volatiles, opioids and relaxa
Intervention General anaesthesia monitored with bispectral index (BIS) or spectral entropy (SE). Targets in the two groups will be BIS (or SE) 50 and 35. We expect 95% of anaesthesia time to be within 5 units of the target range, and no deviations to be greater than 5 minutes. Maintenance phase will be from ten minutes after induction until switching off volatile or hypnotic at the end of the operation. Anaesthesia Standard care using standard anaesthetic hypnotics, volatiles, opioids and relaxants, Intravenous (IV) or gas induction and maintenance, continuous BIS or SE monitoring with computerised data logging (ie: propofol, thiopentone, midazolam, isoflurane, sevoflurane, desflurane, all opioids, all Nonsteroidal Antiinflammatory Drugs (NSAIDs), ketamine, paracetamol, all antihypertensives, statins & diabetic medication etc) as per usual care. Blood pressure target range will be set before opening the BIS randomization envelope and anaesthetists will be requested to maintain patients within these parameters as much as possible.
Sponsors
Dr Timothy Short
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Treatment
Masking
Blinded (masking used)
Eligibility
Sex/Gender
All
Age
60 Years to No maximum
Healthy volunteers
No
Inclusion criteria
Age 60 and over, American Society of Anesthesiologists (ASA) Score 3 or 4, major surgery lasting over 2 hours, expected to stay in hospital two or more nights post-operatively, general anaesthesia including with major regional block, anaesthesia duration expected to be over two hours.
Exclusion criteria
Unable to monitor processed Electroencephalography (EEG)(eg most neurosurgery), not expected to survive one year with or without surgery, unable to consent, eg: dementia, , major psychiatric illness, not expected to be contactable one year later, surgery with wake-up test
Outcome results
None listed