Are you confused about confusion? Well, Dr Steve is delirious about delirium!
This is my first “Ask the Expert” section – where I ask the smartest people I know about a topic that I find tricky.
My guest this post is Dr Stephen Ford, Consultant Psychiatrist, and keen worm-farmer. Steve gets very excited about neural pathways and lesions in old people. And don’t get him started on exotic neurotransmitters…. anyway I thought I would ask him a few garden-variety questions and see where I have been going wrong when it comes to assessing and managing the confused old person.
At interview the presence of impaired attention is a useful sign. Attention has multiple components including attention to stimulus, maintenance of attention and shifting focus appropriately. At the bedside it is usefully tested by observation and the ability to name the months of the year / days of the week in reverse chronological order. Attentional deficits are usually mild in early dementia but much more prominent in delirium.
The presence of new onset visual hallucinations is more consistent with delirium though visual hallucinations do occur in dementia. Often these are accompanied by illusions and delusions and have a dream-like quality in delirious states.
Disorientation to place and the passage of time is prominent in both conditions. A trap is the patient who is reported to have had a disturbed night presenting in an oriented manner on the morning ward round (after reorientation by morning staff). Given the fluctuations in the condition people with a delirium are generally worse over the day than they appear first thing in the morning.
What’s less known is that many classes of medication have anticholinergic activity that may be significant in already compromised individuals (digoxin, warfarin, frusemide, H2 antagonists as per Tune et al Anticholinergic Effects of Drugs Commonly Prescribed for the Elderly. In general suspect any new medications that precede the onset of new confusion. Particular suspects include opioids, benzodiazepines, antihistamines and oral steroids. Dopaminergic medications in those with Parkinson’s disease are a common cause as is elevated lithium levels in those with chronic mood disorders. Drug interactions can frequently precipitate delirium. An under recognised interaction is synthetic opioids with serotonergic medications leading to a serotonergic syndrome (ie tramadol, pethidine [norpethidine is an anticholinergic metabolite], fentanyl or methadone with antidepressants). Buprenorphine and oxycodone are generally safe with antidepressants though may cause confusion in their own right. Beta blockers have been reported to cause delirium though I haven’t seen a clear case myself. Though not strictly medication side effects – alcohol and benzodiazepine withdrawal can be an easily missed cause of confusion in a hospital environment. A summary of the imperfect evidence for particular drug classes is here
Antipsychotics are the least harmful but do carry risks of oversedation, parkinsonism and falls. The 2007 Cochrane review failed to show a difference in efficacy between haloperidol (doses of < 3mg) and atypical antipsychotics in managing delirium. There is some support for antipsychotics shortening the duration of postop delirium but a study with olanzapine and an orthopaedic population found the opposite so the jury is still out. In patients with marked persecutory delusions from their delirium then an antipsychotic may relieve distress. Some preclinical studies suggest atypical antipsychotics may be better at increasing cortical acetyl-choline than haloperidol but this is not well established clinically. I tend to use risperidone as it is cheap, comes in multiple forms and has a reasonable onset and duration of action. The main problem is the alpha blockade and postural hypotension. Doses should be much lower in the elderly than those used for patients with schizophrenia. If injection is required haloperidol is suitable with the main risk that of Qtc prolongation. There is an FDA black box warning about the use of injectable olanzapine and injections of benzodiazapines that dissuades me from using them together. Those with Parkinson’s disease should have dopamine agonists (pramipexole, cabergoline) stopped before entacapone stopped before L-Dopa. Obviously antipsychotics are relatively contraindicated – quetiapine is the least likely to worsen the Parkinson’s disease with doses generally in the 12.5-25 mg range (mean daily dose for psychosis in Parkinson’s disease is 75mg). Haloperidol absolutely should not be given in this population. If aggression is extreme benzodiazepines are the acute sedation of choice in this group.