Post Operative Confusion
OVERVIEW
- often multi-factorial
- not uncommon
- requires a systematic approach (history, review of notes, examination and review of investigation with simultaneous management)
RISK FACTORS
- increased age
- polypharmacy
- pre-existing confusion, delirium and dementia
- pre-existing electrolyte abnormalities
- previous brain dysfunction (CVA)
CAUSES
Anaesthetic
- drug induced: opioids, benzodiazepines, ketamine, anti-emetics, partial reversal, inhalational agents
- hypothermia
- electrolytes: hypoglycaemia
- pain
- respiratory failure: hypoxia, hypercarbia (find cause)
- cardiovascular instability: hypotension (cardiogenic, distributive, hypovolaemic, obstructive) ischaemia, bleeding and anaemia, heart failure
- neurological: ischaemia, seizures, cerebral oedema
- rare: alcohol withdrawal, MH, serotonin syndrome, NMS
Surgical
- bleeding/anaemia
- perforation of viscus -> sepsis/SIRS
- procedure related risks: TURP syndrome
- sepsis
- distended bladder
INVESTIGATIONS
- as directed by likely causes, often requires:
- ABG
- U+E
- glucose
- FBC
- CXR
- ECG
MANAGEMENT
- treat cause!
Resuscitate
- may require airway protection if not rousable or risk of aspiration
- may require mechanical ventilation if in respiratory failure, O2 supplementation
- support circulation while finding cause – fluids/vasoactives/blood products
Electrolytes and Acid-base
- treat life threatening electrolytes abnormalities: hypoglycaemia -> glucose, hypo/hyperkalaemia
- access acid-base status
Specific Therapy
- opioid reversal: naloxone
- benzodiazepine reversal: flumazenil (cautious c/o seizure risk)
- residual neuromuscular blockade: neostigmine and atropine
Underlying Cause
- stop offending medication(s)
- dependent on cause
- disorientation common in dementia patients -> re-orientate, well lit environment, family support, small titrated doses of an antipsychotic
References and Links
CCC Neurocritical Care Series
Emergencies: Brain Herniation, Eclampsia, Elevated ICP, Status Epilepticus, Status Epilepticus in Paeds
DDx: Acute Non-Traumatic Weakness, Bulbar Dysfunction, Coma, Coma-like Syndromes, Delayed Awakening, Hearing Loss in ICU, ICU acquired Weakness, Post-Op Confusion, Pseudocoma, Pupillary Abnormalities
Neurology: Anti-NMDA Encephalitis, Basilar Artery Occlusion, Central Diabetes Insipidus, Cerebral Oedema, Cerebral Venous Sinus Thrombosis, Cervical (Carotid / Vertebral) Artery Dissections, Delirium, GBS vs CIP, GBS vs MG vs MND, Guillain-Barre Syndrome, Horner’s Syndrome, Hypoxic Brain Injury, Intracerebral Haemorrhage (ICH), Myasthenia Gravis, Non-convulsive Status Epilepticus, Post-Hypoxic Myoclonus, PRES, Stroke Thrombolysis, Transverse Myelitis, Watershed Infarcts, Wernicke’s Encephalopathy
Neurosurgery: Cerebral Salt Wasting, Decompressive Craniectomy, Decompressive Craniectomy for Malignant MCA Syndrome, Intracerebral Haemorrhage (ICH)
— SCI: Anatomy and Syndromes, Acute Traumatic Spinal Cord Injury, C-Spine Assessment, C-Spine Fractures, Spinal Cord Infarction, Syndomes,
— SAH: Acute management, Coiling vs Clipping, Complications, Grading Systems, Literature Summaries, ICU Management, Monitoring, Overview, Prognostication, Vasospasm
— TBI: Assessment, Base of skull fracture, Brain Impact Apnoea, Cerebral Perfusion Pressure (CPP), DI in TBI, Elevated ICP, Limitations of CT, Lund Concept, Management, Moderate Head Injury, Monitoring, Overview, Paediatric TBI, Polyuria incl. CSW, Prognosis, Seizures, Temperature
ID in NeuroCrit. Care: Aseptic Meningitis, Bacterial Meningitis, Botulism, Cryptococcosis, Encephalitis, HSV Encephalitis, Meningococcaemia, Spinal Epidural Abscess
Equipment/Investigations: BIS Monitoring, Codman ICP Monitor, Continuous EEG, CSF Analysis, CT Head, CT Head Interpretation, EEG, Extradural ICP Monitors, External Ventricular Drain (EVD), Evoked Potentials, Jugular Bulb Oxygen Saturation, MRI Head, MRI and the Critically Ill, Train of Four (TOF), Transcranial Doppler
Pharmacology: Desmopressin, Hypertonic Saline, Levetiracetam (Keppra), Mannitol, Midazolam, Sedation in ICU, Thiopentone
MISC: Brainstem Rules of 4, Cognitive Impairment in Critically Ill, Eye Movements in Coma, Examination of the Unconscious Patient, Glasgow Coma Scale (GCS), Hiccoughs, Myopathy vs Neuropathy, Neurology Literature Summaries, NSx Literature Summaries, Occulocephalic and occulovestibular reflexes, Prognosis after Cardiac Arrest, SIADH vs Cerebral Salt Wasting, Sleep in ICU
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.
| INTENSIVE | RAGE | Resuscitology | SMACC
