When you’re called to see a sick patient at 2am, your brain will try to jump straight to:

“What’s the diagnosis?”

Resist that urge.

Because on-call medicine is not about diagnosis first.

It’s about:

stabilise first → diagnose later

This single mindset prevents most serious errors.

And it’s exactly how ICU, outreach, and registrars think.

The core principle

Before you think:

❌ “Is this sepsis?”
❌ “Is this PE?”
❌ “Is this stroke?”

Always think:

✅ “Are they alive and stable?”

That’s A–E.

Every patient.
Every time.
No exceptions.

Even if it feels “minor”.

Why this matters

Most overnight deterioration happens because:

airway wasn’t checked
oxygen wasn’t given early
hypotension wasn’t treated
hypoglycaemia wasn’t checked
basics were missed

Not because the diagnosis was difficult.

Simple things save lives.

Not clever things.

What A–E really means (practically)

A–E is not an exam checklist.

It’s a way of thinking:

👉 “Could this patient die in the next 10 minutes?”

If yes → treat immediately.

Don’t wait for tests.

How to apply A–E on the ward

Not textbook style.

Real-life, 3am, ward style.

🅐 Airway — can they protect it?

First look, don’t overcomplicate.

Ask yourself:

talking normally?
gurgling?
snoring?
choking?
reduced GCS?

If they can’t talk properly → airway problem until proven otherwise.

Immediate actions:

sit up
suction if needed
oxygen
call senior help early

Airway problems kill fastest.

Always check first.

🅑 Breathing — are they oxygenating?

Before labs. Before X-rays.

Just look.

Check:

RR
sats
work of breathing
chest movement
cyanosis

Immediate actions:

oxygen (don’t delay)
sit upright
ABG if needed
neb if wheezy

Don’t wait for a chest X-ray to give oxygen.

Treat first.

Investigate later.

🅒 Circulation — are they perfusing?

Most common overnight issue.

Check:

BP
HR
cap refill
urine output
peripheries
mental state

Hypotension = emergency until proven otherwise.

Immediate actions:

2 IV cannulas
bloods
fluids
treat bleeding/sepsis early

Never ignore low BP while waiting for results.

Resuscitate first.

🅓 Disability — brain function

Quick neuro screen.

Not a full neuro exam.

Just:

AVPU or GCS
glucose
pupils
new confusion?

Always check glucose early.

Hypoglycaemia is common and easily fixable.

Don’t miss simple causes.

🅔 Exposure — what are you missing?

Look properly.

You’ll miss things if you don’t expose.

Check:

rashes
bleeding
wounds
distension
infection sources
temperature

So many diagnoses are visible, not lab-based.

The correct order of thinking

When called to a sick patient:

Not:

❌ “What bloods do I need?”

Instead:

✔ A–E
✔ stabilise
✔ THEN think diagnosis

Tests don’t save patients.

Actions do.

Real NHS example

Scenario:

Bleep → “confused patient”

Bad approach:
→ CT head → bloods → long plan

Better approach:
→ A–E → sats 85% → oxygen → improves → pneumonia likely

Simple fix. Big difference.

Always stabilise first.

When to stop thinking and start escalating

If during A–E you find:

airway compromise
persistent hypoxia
hypotension not responding
low GCS
ongoing bleeding
you feel uncomfortable

Call registrar/outreach early.

Don’t complete a “perfect assessment” before calling.

Seniors prefer early calls.

Common junior mistakes

❌ jumping to diagnosis
❌ waiting for bloods first
❌ delaying oxygen/fluids
❌ doing long histories before stabilising
❌ overcomplicating
❌ forgetting glucose

These delay simple life-saving steps.

The senior mindset

Good registrars don’t look smarter.

They look calmer.

Because they always:

A–E → stabilise → think

Same structure. Every time.

No panic. No guessing.

Just system.

Simple mental script to remember

When you reach any sick patient, quietly think:

“Airway. Breathing. Circulation. Disability. Exposure.”

Out loud if needed.

It keeps you structured under pressure.

Take-home concept

On call, you are not a diagnostician first.

You are a resuscitator first.

Stabilise the patient.
Then figure out what’s wrong.

A–E thinking turns chaos into order and prevents most serious mistakes.

When stressed, go back to basics.

Basics save lives.