The Agitated Patient with QTc Prolongation on the Ward

Formulation. This is a delirium superimposed on chronic schizophrenia, multifactorial: pneumonia/hypoxia (SpO2 93%), hyponatraemia 129, hypokalaemia 3.2, hypomagnesaemia 0.62, acute kidney injury (creatinine 1.6 vs 0.9), and possible neuroleptic malignant syndrome prodrome (CK 780, tachycardia, fever, rigidity should be examined for). QTc 512 is a high-risk finding driven by combination of haloperidol + sertraline + electrolyte derangement + possible AKI causing drug accumulation.

Priorities in order:

1. Treat the cause - sepsis workup (blood cultures, urine), antibiotics per pneumonia protocol, oxygen to keep SpO2 ≥94%, IV fluids chosen with attention to sodium correction rate (aim <8–10 mmol/L per 24 h to avoid osmotic demyelination).
2. Correct electrolytes - replace potassium and magnesium; magnesium repletion often needed to correct refractory hypokalaemia and to stabilise QT.
3. Stop or reduce QT-prolonging drugs - hold haloperidol and sertraline; do not simply add another QT-prolonging agent. Review all medicines for anticholinergic and deliriogenic burden.
4. Avoid IM haloperidol and physical restraint where possible - IM haloperidol is relatively contraindicated with QTc >500 and AKI; restraint increases delirium, aspiration risk, rhabdomyolysis and mortality. Use verbal de-escalation, a low-stimulus environment, familiar faces, orientation cues, daylight/noise cycling, early mobilisation, glasses/hearing aids, and family presence.
5. If pharmacological sedation is unavoidable - use the lowest dose of a safer agent with cardiac monitoring; avoid benzodiazepines as sole first-line in a patient with possible sepsis and respiratory compromise but they may be needed for catatonia or severe agitation; consider short-acting agents with ECG monitoring in a monitored bed. Document capacity and least-restrictive justification.
6. Monitor - repeat ECG after electrolyte correction, serial CK, renal function, and delirium screening (e.g. 4AT/CAM) each shift. Reassess for NMS if rigidity or autonomic instability emerges.

Key exam point: agitation in a medically unwell patient is not automatically a psychiatric emergency requiring IM antipsychotic; the correct answer is to treat the delirium and the underlying cause, and to recognise that QTc 512 plus hypokalaemia plus AKI makes haloperidol genuinely dangerous.

Antidepressant. First establish why sertraline was started and whether there was a documented indication. If there is a current moderate-to-severe depressive episode or anxiety disorder, restarting an SSRI is reasonable, but sertraline's QT effect is modest and dose-related; consider a lower dose, correct electrolytes first, and obtain a baseline ECG. If the original indication was weak or the drug was added for 'negative symptoms', there is no good evidence for antidepressants in that role and it should be discontinued.

Antipsychotic. He has chronic schizophrenia, so antipsychotic treatment should continue - but the long-term choice should account for:

• QT risk: prefer an agent with lower QT liability (e.g. aripiprazole, or risperidone if QT is normal), avoid combining multiple QT-prolonging drugs, and keep potassium and magnesium in the normal range.
• Metabolic and renal profile: his AKI episode and possible future medical illness mean dose adjustments and monitoring matter.
• Adherence: consider a long-acting injectable if adherence has historically been poor, but choose one with acceptable cardiac profile.
• Minimum effective dose: review whether 10 mg/day haloperidol was needed; high-dose typical antipsychotics carry higher EPS and QT risk.

Monitoring to specify: baseline and 1–2 weeks post-change ECG if any QT-prolonging drug is used; electrolytes and renal function at each medication review; weight, HbA1c and lipids at least annually; AIMS/abnormal movement screen at each visit; and a written 'sick day' plan advising the patient and carers to seek review if he develops fever, vomiting, diarrhoea or reduced oral intake, because dehydration is what tipped him into delirium and AKI.

Core issue: delirium impairs capacity, but capacity is decision-specific and must be assessed, not assumed.

Reasoning steps:

1. Assess capacity for the specific decision (accepting antibiotics). If delirium is present and he cannot understand, retain, weigh or communicate the information, he lacks capacity for that decision.
2. Use the least restrictive route. In most jurisdictions, treatment for a physical disorder in a patient who lacks capacity can be given under general medical/guardianship or incapacity legislation, in his best interests, without invoking mental health detention. Mental health legislation is generally for treatment of the mental disorder, not for straightforward medical treatment of pneumonia.
3. Best interests must consider his previously expressed wishes, the views of carers, the likelihood of recovery, and the seriousness of untreated pneumonia in a delirious patient. Treating pneumonia is very likely to restore his capacity.
4. Restraint must be proportionate, time-limited, reviewed and documented; chemical sedation should not be used merely to facilitate treatment without a clear clinical rationale and monitoring.
5. Reassess capacity frequently - delirium fluctuates, so consent should be sought again when he is lucid. Document each assessment.

Exam point: the wrong answer is 'detain under the Mental Health Act because he is psychotic'. The right answer separates capacity, best-interests medical treatment, and mental health legislation, and chooses the least restrictive lawful option.