Key Facts

Mental health emergencies are common in the ED and require a compassionate, structured approach that prioritises safety while respecting patient dignity and autonomy. Knowledge of the Mental Health Act and Mental Capacity Act is essential.

Epidemiology

Mental health presentations account for approximately 5-10% of all ED attendances. Self-harm accounts for ~200,000 hospital presentations per year in England. ~6,000 suicides per year in the UK. Psychiatric emergency detention under the MHA has increased significantly over the past decade.

Aetiology

• Acute psychosis: Schizophrenia, bipolar disorder, substance-induced, delirium
• Suicidal crisis: Depression, substance misuse, personality disorder, psychosis, recent bereavement/relationship breakdown
• Acute behavioural disturbance: Psychosis, intoxication, delirium, personality disorder, excited delirium
• Self-harm: Deliberate self-poisoning, cutting, hanging

Pathophysiology

Mental health emergencies may involve psychiatric illness (functional), organic causes (delirium, metabolic, neurological), or substance-related effects. Distinguishing organic from functional causes is critical — organic causes require medical treatment and are associated with higher mortality.

Acute Psychosis

• Hallucinations (auditory most common in schizophrenia; visual suggests organic cause)
• Delusions, thought disorder, disorganised behaviour
• May be agitated, withdrawn, or catatonic

Suicidal Crisis

• Expressed suicidal ideation, plan, intent, means
• Hopelessness, withdrawal, giving away possessions
• Risk factors: Male, >45, living alone, chronic pain, substance misuse, previous attempts, psychiatric illness

Acute Behavioural Disturbance

• Agitation, aggression, violence, self-harm
• May be directed or undirected

Red Flags

• Organic causes: New onset >40, visual hallucinations, clouding of consciousness, abnormal vital signs, focal neurology — investigate medically
• High suicide risk: Ongoing intent, specific plan with means, recent discharge from psychiatric hospital, previous attempt with high lethality method
• Excited delirium: Extreme agitation + hyperthermia + autonomic instability → sudden cardiac death risk
• Self-harm patient wanting to leave — assess capacity; may need MHA

Bedside

• Risk assessment: Suicidal ideation, plan, intent, means, protective factors
• Capacity assessment: Understand, retain, weigh, communicate — document clearly
• Blood glucose: Exclude hypoglycaemia
• Temperature: Exclude infection/NMS/excited delirium
• Drug and alcohol screen: Urine drug screen, blood alcohol

Bloods

• FBC, U&Es, LFTs, TFTs, CRP: Exclude organic cause
• Paracetamol and salicylate levels: If overdose suspected or confirmed
• Blood glucose: Hypo/hyperglycaemia

Imaging

• CT head: New-onset psychosis >40, focal neurology, head injury, reduced consciousness

Special Tests

• Psychosocial assessment: By trained mental health practitioner — NICE CG133 mandates for all self-harm presentations
• Collateral history: Family, GP, community mental health team, ambulance crew

Non-pharmacological

• De-escalation: Calm, non-confrontational approach; maintain safe distance; offer choices; listen actively
• Safe environment: Remove potential weapons/ligature points; 1:1 nursing if suicidal
• Capacity assessment: If patient refuses treatment; document clearly
• Mental Health Act: If patient lacks capacity AND meets criteria for detention

Pharmacological (Rapid Tranquillisation — NICE NG10)

• First-line: Oral lorazepam 1-2mg (if patient will accept)
• IM lorazepam 1-2mg: If oral refused; onset 15-30 min
• IM haloperidol 5mg + promethazine 50mg: If lorazepam insufficient or contraindicated
• Post-rapid tranquillisation: Monitor BP, HR, RR, SpO2, temperature every 15 min for at least 1 hour; pulse oximetry continuously
• Caution: Benzodiazepines in intoxicated patients (respiratory depression); haloperidol in elderly (QTc prolongation)

Mental Health Act Applications

• Section 2: Assessment (28 days) — 2 doctors + AMHP
• Section 3: Treatment (6 months) — 2 doctors + AMHP
• Section 5(2): Doctor's holding power for inpatients (72h) — 1 doctor
• Section 136: Police power to take person from public place to a place of safety (24h)
• Mental Capacity Act: Best interests decision-making for those who lack capacity

Referral Criteria

• Active suicidal intent — psychiatric assessment, consider admission (voluntary or MHA)
• First episode psychosis — urgent psychiatric assessment
• Self-harm — psychosocial assessment before discharge (NICE CG133)
• Acute behavioural disturbance not responding to de-escalation — psychiatric team + security
• Eating disorder with medical compromise — medical admission + eating disorder team

• Suicide attempt survivors: 25% repeat self-harm within 1 year; 3% die by suicide within 10 years
• First episode psychosis: 80% respond to antipsychotics; long-term prognosis varies; early intervention services improve outcomes
• De-escalation: Effective in ~80% of cases; reduces need for restraint and pharmacological intervention
• Rapid tranquillisation: Effective within 15-60 min in most cases
• Excited delirium: ~10% mortality; risk of sudden death during/after restraint

Mental Health Act Sections (England & Wales)

Suicide Risk Assessment Framework