POCD defined as: long term cognitive dysfunction in at least 1 domain: memory, learning, concentration, speed of processing.
- Manifests days to weeks in 25% elderly post-op patients.
- 99% have resolved by 1 year.
Risk factors: (bold = strongest)
- Patient: Age>60, low level of education, Hx chronic disease, other disorientating factors (e.g. pre-op cognitive impairment, visual & hearing loss, depression, physical restraints, ETOH abuse)
- Surgical: Duration, extent of surgical trauma,
- Anaesthetic: Benzos, Opioids, General > Regional, Depth of anaesthesia (BIS<40)
Anaesthesia is but one factor in a complex mix contributing to POCD… but
- Regional techniques which reduce hypnotic / benzo / opioid doses may be beneficial
- Deep planes of anaesthesia are probably not beneficial … BIS may be beneficial in reducing hypnotic dosing and by inference reducing POCD incidence
- Doing the simple things well – multimodal analgesia, PONV prophylaxis, IVF management, normothermia, normoxia, normocarbia etc. sees a crisper patient in recovery and may help reduce the risk of POCD