6 General adult psychiatry6.3 Liaison psychiatry
6.3.2 Psychiatric advice to specialist medical services
6 min read2 figures
Written by Resident Doctor Committee · Published
The liaison consultation
The referral question is clarified with the referrer before the patient is seen, along with the records, the medical treatment and what is worrying the team.
A useful consultation ends with agreed actions, a named person responsible for each, follow-up, and a plan the ward can actually deliver.
Delirium, refusal and sedation
Delirium is looked for before disturbed behaviour is put down to psychiatric illness, by checking for pain, infection, hypoxia, urinary retention, constipation and medication effects.
For hyperactive delirium with distress or risk that non-drug measures have not settled, NICE (the National Institute for Health and Care Excellence) suggests short-term low-dose haloperidol.
Haloperidol in delirium needs a normal QTc (the QT interval corrected for heart rate) and no Parkinson's disease or Lewy body dementia.
Refusal of treatment needs a capacity assessment for that specific decision, because an unpopular choice does not prove incapacity.
For rapid tranquillisation in cardiovascular disease, with a prolonged QT interval, or when no electrocardiogram (ECG) is available, NICE advises intramuscular lorazepam alone, because it carries no QT risk.
Intramuscular olanzapine and a parenteral benzodiazepine are not given together, and a benzodiazepine needed afterwards waits at least one hour, with close monitoring.
Cardiac disease
Major depression affects roughly one in five people with coronary heart disease, including after acute myocardial infarction, which is several times the general population rate.
Sertraline is first choice for depression after myocardial infarction or acute coronary syndrome, because it has the strongest safety and efficacy evidence (the SADHART trial) and little effect on QT.
The alternatives have cardiac drawbacks: citalopram prolongs QT in a dose-related way, tricyclics and MAOIs (monoamine oxidase inhibitors) carry cardiac risks, and venlafaxine raises blood pressure.
Aripiprazole suits psychosis with atrial fibrillation because it barely affects QT or rhythm and, unlike olanzapine and clozapine, has not been linked with atrial fibrillation.
ECG changes to recognise
Cause | Mechanism or clue | ECG |
|---|---|---|
Purging | Potassium loss | ST depression, flattened or inverted T waves, prominent U waves |
Clozapine myocarditis | Usually first month; fever, chest pain, rising troponin | Diffuse concave ST elevation sparing aVR |
Tricyclic overdose | Fast sodium channel blockade | Broad QRS complexes, terminal R wave in aVR |
Haloperidol, clarithromycin, donepezil | Additive hERG potassium channel blockade | Prolonged QTc, with the QT filling over half the RR interval |
Cancer and tamoxifen
Tamoxifen is a prodrug that cytochrome P450 2D6 (CYP2D6) activates to endoxifen, so potent CYP2D6 inhibitors may reduce its anticancer effect.
Fluoxetine, paroxetine and bupropion are potent CYP2D6 inhibitors and are avoided in women taking tamoxifen.
Mirtazapine, with weak or no CYP2D6 inhibition, is preferred, and citalopram and escitalopram are only weak inhibitors.
Liver disease
Glucuronidation is relatively preserved in cirrhosis, so lorazepam, oxazepam and temazepam, which are cleared by direct glucuronidation and have no active metabolites, are the preferred benzodiazepines.
Long-acting benzodiazepines that rely on hepatic oxidation and have long half-lives and active metabolites are avoided.
Sertraline, started low and raised slowly, has the best antidepressant tolerability record, and citalopram and paroxetine are also reasonable.
Duloxetine is excluded by its licence in hepatic impairment and has caused raised transaminases and hepatitis.
Agomelatine is contraindicated in hepatic impairment, including cirrhosis or transaminases above three times the upper limit of normal, because it has caused hepatitis and liver failure.
Amisulpride undergoes little hepatic metabolism and is cleared largely unchanged by the kidneys, and low-dose haloperidol is the other usual antipsychotic.
Paliperidone is mostly excreted unchanged in urine and needs no dose change in mild to moderate impairment, whereas risperidone relies on hepatic CYP2D6 and its unbound fraction rises.
Lithium is the preferred mood stabiliser because the kidneys clear it without liver metabolism, and renal and thyroid function are monitored.
Renal disease
Lithium is excreted almost entirely in urine and has a narrow range, so falling filtration, dehydration and interacting drugs raise its level, and it can itself damage the kidney.
At stage 4 kidney disease, lithium is best avoided, or the dose is cut sharply with frequent levels.
When the eGFR (estimated glomerular filtration rate) is below 30, hepatically cleared, less anticholinergic antipsychotics are preferred: haloperidol, or olanzapine started at about 5 mg daily.
Amisulpride is cleared by the kidney and is avoided, and sulpiride also depends heavily on renal clearance.
In severe renal impairment, sertraline or citalopram is the usual antidepressant, because neither needs a routine renal dose change.
Clozapine's licence lists severe renal disease as a contraindication, alongside severe cardiac disease.
Epilepsy
Selective serotonin reuptake inhibitors (SSRIs) have little effect on seizure threshold at therapeutic doses and are first-line antidepressants in epilepsy.
Drug | Effect on seizure threshold |
|---|---|
SSRIs, mirtazapine, duloxetine | Lowest-risk group |
Sulpiride | Little effect |
Tricyclics | Lower it more than SSRIs; clomipramine is among the most epileptogenic, with dose-related risk and a 250 mg daily cap |
Clozapine | Dose-related; about 5% have seizures above 600 mg daily, often after myoclonic jerks |
Sertraline has few important interactions with anticonvulsants.
Seizures on clozapine are managed by checking the level, reducing the dose and adding an anticonvulsant if they continue.
Sulpiride is excreted unchanged by the kidneys, so carbamazepine's enzyme induction does not change its level.
HIV
Depression is the most prevalent psychiatric disorder in human immunodeficiency virus (HIV) infection, at roughly two to three times the general rate, ahead of anxiety, adjustment disorder, substance use and psychosis or mania.
The excess comes from infection-immunological, psychosocial and exogenous (medication and substance) factors, not from inherited genetic vulnerability.
Psychological treatments with evidence are cognitive-behavioural, interpersonal and problem-solving approaches, including remote and lay-delivered forms, while therapies developed for personality disorder have not been tested.
With antiretrovirals, SSRIs with minimal cytochrome P450 inhibition (citalopram, escitalopram, sertraline) are preferred, whereas fluoxetine is a strong CYP2D6 inhibitor.
With epilepsy as well, SSRIs (escitalopram and citalopram carry the lowest interaction risk) and mirtazapine suit best, while bupropion and tricyclics are proconvulsive.
MAOIs are not recommended in HIV, and trazodone is limited by interactions and side effects.
Low-dose risperidone, the second-generation antipsychotic with the largest evidence base, is first choice in psychosis because people with HIV are very sensitive to extrapyramidal effects, and clozapine is held back.
Efavirenz is linked with depression, mania, psychosis and suicidal ideation, so it is avoided in patients at high psychiatric risk.
St John's wort induces CYP3A4 and lowers antiretroviral levels, so it is contraindicated with protease inhibitors because of the risk of virological failure and resistance.
Other medical comorbidity
Duloxetine, a serotonin-noradrenaline reuptake inhibitor, is licensed for major depression and diabetic peripheral neuropathic pain, so one dose treats both, whereas SSRIs have no useful analgesic action.
With warfarin, citalopram and escitalopram are preferred because they only weakly inhibit CYP2C9 and CYP1A2, unlike fluoxetine, fluvoxamine and paroxetine.
Corticosteroids are the commonest drug cause of new manic symptoms in medical inpatients, and the risk is dose-related, with a mania-like state appearing within days of high doses.
Short high-dose courses, as for a multiple sclerosis relapse, more often cause elevated mood or hypomania than depression or psychosis.
Psychological impact, continuity and consent
Assessment covers fear, loss, uncertainty and changes in body image or independence, and after intensive care it explores frightening memories and gaps in recall.
Functional symptoms are explained positively from the clinical findings, with a treatment plan, rather than by presenting normal investigations as proof that nothing is wrong.
For recurrent health anxiety, the team agrees planned reviews, a consistent clinician and clear indications for tests, because repeated reassurance and investigation keep anxiety going.
The general practitioner receives an agreed prescribing and monitoring plan, not an unannounced transfer of responsibility.
Information is shared within direct care, normally on implied consent when the patient has been informed and has not objected, and only as much as is needed.
Incapacity does not permit unrestricted coercion, so any intervention needs an applicable legal basis and must be proportionate.