Failure to wake and delirium

Question 1

What are the main reasons patients fail to wake after anaesthetic

Answer 1

4S
Sedatives
Stroke
Seizure
Sudden metabolic derangement (hypoxia, hypercarbia, hyponatraemia, hypo/hyperglycaemia, acute uremia, acute ammonemia)

Question 2

Outline a basic approach to assess a patient who fails to wake

Answer 2

ABCDEFG
Airway, breathing, circulation
Drugs - consider antagonists
Eyes - check size, symmetry and reaction to light
Function - assess response to stimuli, GCS
Glucose -

Question 3

Define delirium

Answer 3

Disturbance in consciousness with reduced ability to focus, sustain or shift attention
Development of perceptual disturbance
Acute onset and fluctuates during course of day
Evidence from Hx, exam that it is caused by direct physiological consequences of a general medical condition

Question 4

What are the risk factors for development of delirium post anaesthetic

Answer 4

Age >65
Cognitive impairment, depression
Functional impairment
Sensory impairment (particularly visual and hearing)
Decreased oral intake, dehydration
Drugs - polypharmacy, EtOH, psychoactives, sedatives, narcotics, anticholinergics
Comorbidities - severe illness or neurologic disease
High risk surgery - prolonged, cardiac, THR
Pain
Sleep deprivation
Immobility

Question 5

Which interventions peri-op could be trialled to reduce post-op delirium

Answer 5

Regional techniques (no evidence of benefit)
Preventing periop haemodynamic instability (no evidence of benefit)
Continuing pharmacological therapy for neuropsychiatric disorders
Managing blood loss (some evidence delirium assoc with greater intra-op blood loss)

Question 6

Outline a treatment course for post-op delirium

Answer 6

Identify and manage possible underlying risk factors - correct metabolic and electrolyte disorders
- Remove triggers such as drugs
- Treat other possible triggers (pain, hypotension, dehydration, full bladder)
Provide a suitable recovery environment
Ensure sensory aids are available
Reassure, reorientate patient
Consider family members/carers
Can trial verbal techniques to calm patient
Perform a neurological exam looking for focalising signs
If treatable causes corrected and neurology excluded then:
Midazolam 1mg increments
Haloperidol or Droperidol 1mg increments
Olanzapine

Question 7

What investigations could be useful for post-op delirium

Answer 7

ABG - Hypoxia, CO2 narcosis, acidosis
U&Es + Ca - Electrolyte derangement
Haemocue - Hb drop
FBC - Hb drop, elev WCC (sepsis)
ECG - MI
CXR
CT head