Stage 00

Pre-arrival and triage

Before the patient is in front of you

Trigger an ABD alert if any of

Pre-alert describing agitation, constant physical activity, bizarre behaviour, fear or panic
Unusual or unexpected strength, or apparent imperviousness to pain
Sustained non-compliance with police or ambulance staff
Hot to touch, sweating, rapid breathing, tachycardia
Patient restrained on arrival
Known stimulant or novel psychoactive substance ingestion with agitation
Patient detained under s136 Mental Health Act

These recognition features originate in the excited delirium literature — a contested construct that is not recognised in the UK — and are retained by RCEM only because no better UK-specific evidence exists. Use them to raise your index of suspicion, never as a label, and never as a justification for prolonged restraint.

Features may be absent if the patient has already had pre-hospital sedation or anaesthesia, has reached exhaustion, or is peri-arrest. Take a detailed pre-hospital history: observed behaviour, de-escalation attempted, capacity assessments, restraint type and duration, use of force or a controlled energy device, and any sedation given with adverse events.

On alert, assemble

ED senior decision-maker (ST4+ / SAS / consultant)
Nurse in charge
Security team — minimum four for safe restraint if required
Early consideration: anaesthetics / critical care if severe
Mental health liaison notified in parallel, not instead

Space

A designated safe assessment room:

Two exits, doors opening outwards
No ligature points
No loose equipment that could be a weapon or used to barricade an exit
Quiet, low stimulus, not too warm
Constantly observable; staff able to signal for help easily
Monitoring available, resus trolley accessible

Ask about what has already been done to them

Police and ambulance services have their own ABD guidance (College of Policing, JRCALC). Ask directly — this is rarely offered unprompted, and it changes what you are looking for.

Controlled energy device (TASER) — note number and duration of discharges, and where the barbs landed. See RCEM's separate Controlled Energy Device Attendances guidance
PAVA or other incapacitant spray — decontamination and eye irrigation may be needed
Restraint — type, position, and total duration, including in the vehicle

Pre-hospital sedation — some ambulance services and pre-hospital critical care teams give it; get drug, dose and time
Custody healthcare staff may have given oral benzodiazepines. Prescribing ability varies; ask for what was given and for any observations they recorded
Police information — family accounts, bystander accounts, PNC records on medication, drugs, medical and psychiatric history

ABD is a distracting presentation. Co-existing toxicological problems and traumatic injuries are easy to miss while attention is on the behaviour.

Stage 01

Immediate safety and physiological screen

Run both limbs simultaneously

Limb A — Safety

One team leader, one communicator only
Remove weapons and ligature risks; clear the space
Never use prone restraint. If restraint is already in progress, move to supine or lateral in the shortest possible time
Restraint clock starts — document time, position, personnel
Assign a safety person — someone not involved in the restraint or any other intervention, whose only job is to watch the patient's condition
Do not attempt restraint with insufficient numbers. Untrained staff should not be asked to restrain
Remove restraint at the earliest opportunity

Restraint is not neutral. Continued exertion under restraint is thought to contribute to poor outcomes through rising catecholamines, worsening hyperthermia and metabolic acidosis. The link between restraint and death remains debated, but there is no high-quality evidence that any method of restraining an undifferentiated, co-morbid ABD patient is risk-free. Prolonged restraint should itself prompt rapid tranquillisation — see Stage 02.

Limb B — The non-negotiable four

Obtain opportunistically, even in a resisting patient.

Parameter	Why it cannot be deferred
Capillary glucose	The single most reversible and most missed cause
SpO₂ / respiratory rate	Hypoxia and hypercapnia cause agitation
Temperature	Sepsis, toxidrome, hyperthermic ABD, meningitis
GCS / pupils	Head injury, opioid, anticholinergic, post-ictal state

If these cannot be obtained because of the level of disturbance, that alone is an indication to proceed to pharmacological control in order to assess — not merely to sedate.

Stage 02

Red flag screen for severe or hyperthermic ABD

One flag is enough

Any one of these is a physiological emergency, not a behavioural one

Temperature ≥ 38.5 °C
Persistent tachycardia > 120 with agitation
Sustained resistance to restraint with apparent insensitivity to pain
Prolonged struggle > 10 minutes against restraint
Rigidity, clonus, or sustained tremor
Sudden transition from extreme agitation to calm or collapse — imminent cardiac arrest

Action if a red flag is present

Move to resus
Anaesthetic / critical care call
Sedate — rapid tranquillisation comes before cannulation in a struggling patient (Stage 05)
Full monitoring once tolerated: continuous ECG, SpO₂, NIBP, temperature
Aggressive active cooling
IV access and early crystalloid once the sedative has worked — rhabdomyolysis and metabolic acidosis are the killers
Early VBG: lactate, pH, potassium
Prepare for peri-arrest — hyperkalaemia and profound acidosis are the arrest mechanisms

If they arrest, resuscitate for longer than feels natural. Most ABD is toxicological in origin, so prolonged resuscitation efforts are specifically recommended. Correct hyperkalaemia and acidosis aggressively throughout.

Stop restraining before you do anything else

Three of the six red flags above are descriptions of a patient fighting a hold. Exertion under restraint drives catecholamine release, hyperthermia, lactic acidosis and rhabdomyolysis — and RCEM is explicit that prolonged restraint should itself prompt rapid tranquillisation. It is also the specific reason serotonin syndrome should not be physically restrained.

If rigidity, clonus or sustained struggle is present, sedation replaces restraint. It is not an escalation of force; it is the treatment for the physiology.

The patient who suddenly goes quiet after a prolonged struggle has not settled. Treat sudden calm as pre-arrest until the monitor says otherwise.

Stage 03

Differential framework

Reversible and lethal first

Hypoxia and hypoperfusion
Pneumothorax, PE, sepsis, shock, raised ICP, carbon monoxide.
Hypoglycaemia and metabolic
Hyponatraemia, hypercalcaemia, hepatic encephalopathy, DKA, thyrotoxicosis and thyroid storm, uraemia, heat stroke.
Intracranial
Traumatic brain injury — may be occult in an intoxicated patient — SAH, encephalitis, non-convulsive status, post-ictal state, space-occupying lesion.
Toxicological
Intoxication — alcohol, stimulants (cocaine, amphetamine, MDMA), synthetic cannabinoids, GHB, ketamine, NPS, anticholinergics.
Withdrawal — alcohol, benzodiazepines, opioids, baclofen.
Toxidromes — serotonin syndrome, NMS, malignant hyperthermia, anticholinergic delirium, sympathomimetic, acute dystonia.
Infective
Meningitis, encephalitis — including anti-NMDA receptor encephalitis, classically a young patient with a psychiatric presentation who deteriorates on a psychiatric ward — sepsis, urinary sepsis in the frail.
Pain, distress, unmet need
Urinary retention, constipation, fracture, undertreated pain, sensory overload.
Psychiatric
First-episode psychosis, mania, personality disorder crisis, PTSD.

Rule: a known psychiatric history does not lower the threshold for organic screening. It raises it.

Branch from point 04 — Toxidromes

Hyperthermic and movement toxidrome differentiator

Six conditions that present as a hot, agitated or rigid patient and are routinely confused with one another. They separate on onset speed, muscle tone, reflexes, and whether the skin is wet or dry. Enter what you find and the ranking updates live; each condition carries its own recognition criteria, management and trap.

Open the differentiator

Stage 04

De-escalation

Always attempted first where feasible

Environment

Reduce stimulus — dim lights, reduce noise, minimise the number of staff visible
Maintain at least one metre and an unobstructed exit for both parties

Manner

Open posture, hands visible, avoid sustained direct eye contact
One voice only, short sentences, name the emotion
Do not argue the content of delusions
Offer genuine choices to restore a sense of control

Practical offers

Blanket, phone, quieter space, access to a familiar person
Analgesia if pain is plausible
Toilet access — retention and urgency are common precipitants
Offer oral sedative medication as a genuine choice (Stage 05)

Do not offer food or drink if sedation or general anaesthesia is likely to be needed.

Offer oral medication as a choice before parenteral

Oral lorazepam, olanzapine orodispersible or promethazine — doses in Stage 05.

Success here preserves the therapeutic relationship and avoids the physiological risk of restraint. Offering it and being refused still matters — it is how you evidence least-restrictive practice.

Stage 05

Rapid tranquillisation

RCEM BPG v2 — ketamine or droperidol first line in severe ABD

Decide it, and score it, before you draw anything up

Parenteral rapid tranquillisation is a senior decision. RCEM frames it on five points:

The patient lacks capacity
The patient represents a significant danger to themselves or others
The patient requires emergency treatment or investigation
The patient is severely agitated
The doctor considers this may be potentially life-threatening ABD

The potent agents below are reserved for Sedation Assessment Tool 2 or 3. Score it and write the score down.

Score	Responsiveness	Speech
3	Combative, violent, out of control	Continual loud outbursts
2	Very anxious and agitated	Loud outbursts
1	Anxious / restless	Normal or talkative
0	Awake and calm / cooperative	Speaks normally
−1	Asleep but rouses if name is called	Slurring or prominent slowing
−2	Responds to physical stimulation	Few recognisable words
−3	No response to stimulation	None

Calver, Stokes & Isbister, EMA 2011 — reproduced in RCEM BPG appendix 1.

Oral first

Offer oral medication as part of de-escalation

Offering oral medication is how you establish that you used the least restrictive option in a patient who lacks capacity. Do it even when you expect it to be declined, and record it.

Lorazepam 1–2 mg PO — maximum 4 mg in 24 hours
Olanzapine 10 mg orodispersible
Promethazine 25–50 mg PO

Reassess at 30–45 minutes.

Prepare before you give it — short safety brief

Senior doctor with critical care experience
Drug drawn up and prepared correctly; antidotes available if applicable
Oxygen and high-flow reservoir mask on the patient or immediately ready
Monitoring: ECG, pulse oximetry, BP, ETCO₂

Equipment for complications — airways, suction, bag-mask
Adequate number of personnel
Brief the team: roles, intended plan, anticipated problems, restraint considerations, IV access plan, plan for moving to resus, and who decides when restraint is relaxed

Do not cannulate a patient who is being actively restrained if it can be avoided — the risk of needlestick and injury to staff is real. Give the IM drug first, then cannulate once it has worked.

First line

Parenteral rapid tranquillisation — severe ABD (SAT 2–3)

Choose one

Ketamine 4 mg/kg IM — or titrate to effect IV if access is already safe
Droperidol 5–10 mg IM

Practicalities that catch people out

Higher concentrations than you normally stock may be needed for IM injection — know where they are kept and how they are differentiated from the standard strength
Large volumes may need splitting across multiple sites
Reduce the IV dose if given after an IM dose
Halve the dose in the over-65s, and start low and go slow in the frail
Strongly consider critical care support if full first doses have not worked

Choosing between them

Ketamine — fastest to adequate sedation, cardiovascularly stable, preserves respiratory drive and airway reflexes. Give it in resus where practicable, or with resuscitation equipment immediately to hand
Droperidol — fewer adverse events than lorazepam or midazolam, and fewer patients needing a second agent than haloperidol or midazolam. Less suitable if the patient takes antipsychotics, or where the presentation may be antipsychotic-related (anticholinergic syndrome, akathisia)
Neither haloperidol nor droperidol in Parkinson's disease or Lewy body dementia
Midazolam 5–10 mg IM may be considered instead where a transient rise in heart rate or blood pressure is particularly relevant — ischaemic heart disease, or possible cocaine-induced psychosis. Weigh it against midazolam having more adverse events than droperidol, and benzodiazepines causing more respiratory adverse events than antipsychotics

Is ketamine contraindicated in sympathomimetic toxicity? No. Its dissociative effect appears to reduce adrenergic features, and its own sympathomimetic effect is unlikely to cause significant adverse consequences in severe ABD. The BNF lists hypertension among ketamine's cautions and RCEM explicitly addresses that, recommending ketamine first line for ABD regardless, including with co-existing drug ingestion or head injury. What it asks for is a watch, not a withhold: if tachycardia or hypertension worsens after ketamine, add a benzodiazepine — the effects are synergistic and the risk is cardiac.

On the intubation figures: the high post-ketamine intubation rates in the literature come predominantly from pre-hospital practice and largely reflect securing the airway for transport. They are not a reason to withhold ketamine in a resus room. Be ready to intubate regardless.

If unavailable

Second line — where ketamine and droperidol are not stocked

Midazolam 5–10 mg IM — also an option first line where sympathomimetic features are the concern, see above
Lorazepam 4 mg IM
Haloperidol 5 mg IM ± lorazepam 2 mg IM — the combination sedates better than either alone, with no increase in adverse effects. ECG as soon as feasible; QT risk; higher dystonia rate
Olanzapine 10 mg IM — do not give with a parenteral benzodiazepine within 1 hour (respiratory depression and hypotension)

Flumazenil is a precaution, not a plan. Have it available if you use parenteral benzodiazepines — initial dose 200 micrograms slowly — but it is hazardous in exactly this population: mixed overdose involving tricyclics, and benzodiazepine-dependent patients. Do not let its existence justify a larger benzodiazepine dose.

Check your own stock. Many UK EDs do not hold droperidol. Find out before the pre-alert, not during it, and agree the local substitution in writing.

Once the sedative has taken effect

Establish and secure intravenous access
Monitor in a high-dependency area — resus room
Maintain sedation with IV bolus medication until a definitive management plan is arranged
Correct electrolyte, glucose and acid–base abnormalities; correct hyperthermia
Look actively for DIC and rhabdomyolysis
Institute other emergency treatments and investigations

Before you give a second dose — stop and decide

Suspected mental health presentation — repeat IM doses should be given in liaison with mental health services, pending a mental health practitioner review
Non-psychiatric cause suspected, and sedative needs are beyond ward-level care — critical care input is required, not more of the same
Consider advice from NPIS / TOXBASE — most ABD is toxicological
Aim to de-escalate from resus into the department's best ABD environment at the earliest opportunity

Repeated intramuscular dosing without a plan is how a behavioural presentation quietly becomes a critical care one. The second dose is a decision point, not a repeat prescription.

Maintenance

Keeping control after the first dose

Agree ongoing sedation with the admitting speciality and follow local policy. Patients with ABD frequently need higher doses than anticipated. Options outside critical care:

Diazepam 0.3 mg/kg IV (or oral), titrated, repeated as needed
Lorazepam 0.03 mg/kg IV (or oral), titrated, repeated as needed
Haloperidol 2.5 mg IM (1.25 mg elderly) or 2 mg oral (1 mg elderly), repeated as needed
Olanzapine 5–10 mg IM or oral (2.5–5 mg elderly), repeated up to twice in 24 hours

By suspected cause

Serotonin toxicity with severe psychosis or hyperthermia — chlorpromazine 25–50 mg IV or IM, in addition to benzodiazepines
Alcohol or sedative withdrawal — benzodiazepines are effective
GHB / GBL withdrawal — add baclofen; see TOXBASE

Benzodiazepines may worsen delirium and cause prolonged, excessive sedation in older patients. Haloperidol and olanzapine may prolong the QT or cause arrhythmias.

Anaesthesia

Induction and intubation

Refer early to critical care if any of these look likely

Requirement to secure the airway
Inadequate spontaneous ventilation to maintain oxygenation and prevent hypercapnia
Severe agitation despite maximal safe sedative doses
Persistent metabolic derangement
Requirement to manage hyperthermia
Requirement to support other interventions or investigations

Anaesthetic considerations specific to ABD

Ketamine induction — these patients are dehydrated and physiologically fragile; minimise haemodynamic instability. Account for sedatives already given
Avoid suxamethonium — hyperkalaemia is likely
Avoid opioids — morphine may worsen hypotension through histamine release; fentanyl is a particular concern in possible serotonin syndrome, as it produces an efflux of serotonin
Ventilate throughout the RSI to maintain respiratory compensation for severe metabolic acidosis

This is a legitimate endpoint, not a failure of the algorithm.

Stage 06

Post-sedation monitoring

Mandatory

Treat every sedated ABD patient as a post-procedural sedation patient

Continuous SpO₂, ECG and capnography where available
NIBP and NEWS2 every 5 min for 15 min, every 15 min for 1 hour, then hourly until fully alert
Temperature every 30 min if there is any hyperthermia
Level of consciousness scoring
Airway-trained staff present, with naloxone and full resuscitation equipment immediately available
Patient positioned lateral or head-up — never prone
One-to-one nursing until fully alert

Flumazenil as a precaution, not a routine reversal. Keep it available whenever parenteral benzodiazepines are used — 200 micrograms slowly — but it is hazardous in mixed overdose involving tricyclics and in benzodiazepine-dependent patients, both common in ABD. Reversal is a considered decision, not a reflex.

Stage 07

Investigations once safe

Baseline for all

VBG — glucose, sodium, potassium, lactate, pH, CO₂. Fastest and highest yield
FBC, U&E, LFT, CRP, calcium, magnesium, troponin
CK and coagulation profile — rhabdomyolysis and DIC after restraint or stimulant use
ECG — QT, ischaemia, sodium channel blockade
Paracetamol and salicylate levels if there is any possibility of self-harm
Bladder scan for urinary retention

Add according to the differential

CT head — low threshold if trauma, focal signs, headache, anticoagulation, persisting reduced GCS, or a first presentation over 40
Lumbar puncture — suspected meningitis, encephalitis, or autoimmune encephalitis
Coagulation, ammonia, TFTs, blood cultures
Urinary drug screen — limited acute value, rarely changes management, do not delay treatment for it

Stage 08

Legal framework

Document explicitly

State in the notes which framework applies, and why

Situation	Framework
Patient lacks capacity, treatment in their best interests	Mental Capacity Act 2005 — best interests decision, least restrictive option
Immediate risk to life, no time for formal assessment	Common law doctrine of necessity
Brought to ED by police from a public place	s136 Mental Health Act — ED as place of safety, 24 hour clock
Already admitted to a ward	s5(2) holding power — not available in the ED; an ED attender is not an inpatient
Formal detention needed for psychiatric treatment	MHA assessment — s2 / s3
Aged 16 or 17	Mental Capacity Act 2005 for capacity; consent under s8 Family Law Reform Act 1969
Under 16	Gillick competence, parental responsibility, Children Act considerations
Scotland / Northern Ireland	Adults with Incapacity (Scotland) Act 2000 · Mental Capacity Act (NI) 2016

Document these as well — this is the record a review will read

Relevant features from the collateral history
The features that supported managing this as ABD
Attempts at verbal and environmental de-escalation
Mental capacity assessment

Restraint applied — type, duration, indication, proportionality
Security or police involvement, including use of force and any controlled energy device use
Sedative strategy and any adverse events
Involvement of other specialties, and who was part of the decision

Stage 09

Special populations

Autism and learning disability

Agitation is frequently communication of pain, sensory overload, or a change in routine
Reduce stimulus before reaching for medication
Involve carers and family immediately — they know baseline and triggers
Ask for the hospital passport or care plan
Higher sedation threshold; document reasonable adjustments made (Equality Act duty)
Screen actively for the silent causes: constipation, dental pain, otitis, retention, fracture

Children and young people

Adolescents have a similar differential and pose similar challenges to adults; in life-threatening situations the sedative strategy is likely to be the same
Pre-adolescent children have a different differential — brief restraint is more likely to succeed where verbal and environmental de-escalation fails
Severe agitation in a child is not automatically ABD
Involve paediatrics and CAMHS early; weight-based dosing; lower thresholds for organic causes
Parental presence is usually de-escalating, occasionally not — assess
Safeguarding is mandatory, not optional

Older and frail adults

Delirium until proven otherwise — screen with 4AT. Stimulant drugs are a less likely cause here; hyperactive delirium is more likely, and delirium guidance may fit better than this algorithm
Halve all sedation doses in the over-65s — start low, go slow
Neither haloperidol nor droperidol in Parkinson's disease or Lewy body dementia
Benzodiazepines may worsen delirium and cause prolonged, excessive sedation
Avoid anticholinergics; they worsen delirium
Antipsychotics increase stroke and mortality risk in dementia — use only if there is genuine risk of harm, and for the shortest duration

Pregnancy

Involve obstetrics; left lateral tilt in restraint or after sedation
Avoid a prolonged supine position beyond 20 weeks
Benzodiazepines generally preferred acutely — discuss with obstetric pharmacy

Stage 10

Disposition

Do not discharge or refer from a state of restraint or sedation

The patient must be reassessed awake and calm.

Organic cause	Appropriate medical or surgical specialty, regardless of psychiatric history
Hyperthermic	Rhabdomyolysis or acidosis → critical care
Toxicological	Observation area with monitoring; discuss with TOXBASE / NPIS if uncertain
Psychiatric	Medically cleared → mental health liaison, with a documented physical assessment and normal observations
Discharged	Safety netting, GP letter, Yellow Card if an adverse drug reaction, safeguarding referral if indicated

Always consider safeguarding: exploitation, county lines, domestic abuse, self-neglect, modern slavery.

Stage 11

After the event

Debrief the team — hot debrief within the shift, especially if restraint, ketamine or a peri-arrest occurred
Debrief the patient when able — explain what happened and why. This materially reduces trauma and future presentations
Datix / incident report for restraint, prone positioning, injury to staff or patient, or any deterioration
Governance review for any ABD case requiring ketamine, droperidol or intubation, or resulting in critical care admission

Summary

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Print this

Alert and assemble — space, team, security, senior
Glucose, sats, temperature, GCS — non-negotiable
Screen for red flags — fever, sustained struggle, sudden calm → resus, not restraint
Think organic first — hypoxia, hypoglycaemia, head injury, toxin, infection
De-escalate — environment, manner, offers, oral medication as a choice
Score the agitation (SAT), brief the team, then sedate — ketamine 4 mg/kg IM or droperidol 5–10 mg IM first line in severe ABD; midazolam, lorazepam or haloperidol only if those are unavailable
Monitor as post-sedation — continuous, one-to-one, never prone
Investigate — VBG, CK, ECG first
Name the legal framework in the notes
Reassess awake before disposition
Debrief patient and team

Acute behavioural disturbance in the emergency department — red flag screening, de-escalation, rapid tranquillisation, post-sedation monitoring and the legal framework for adults and young people

The disturbance is a sign,not a diagnosis.