The A to E Assessment

Introduction

The ABCDE approach is the single most important framework in acute and emergency medicine. It is a structured method for assessing and simultaneously resuscitating any patient who is acutely unwell, deteriorating, or peri-arrest, regardless of the underlying diagnosis.¹

Its power lies in its order. Airway, Breathing, Circulation, Disability, Exposure are addressed strictly in sequence because each represents a physiological priority: an obstructed airway kills within minutes, a breathing problem within minutes to hours, a circulatory problem more slowly still. Working through the letters in order means the most immediately dangerous problem is always found and treated first, whatever the eventual diagnosis turns out to be.

It is deliberately diagnosis-agnostic. You do not need to know why a patient is unwell to start an ABCDE assessment - the same structure applies whether the cause turns out to be sepsis, a tension pneumothorax, anaphylaxis or a myocardial infarction. This is what makes it examinable in almost any clinical scenario and indispensable on the wards.

Core principles

• Complete a full set of observations first - a NEWS2 score frames the whole assessment and tells you how worried to be before you have even started
• Treat problems as you find them - do not wait until the end of the assessment to act on a life-threatening finding
• Reassess after every intervention - an intervention that has not been reassessed is an intervention you cannot be sure has worked
• Do not move to the next letter until the current one is addressed, or at least until immediate treatment has been started
• If the patient deteriorates at any point, go back to A and work through the letters again
• Call for help early and use SBAR - a structured handover gets senior help to the bedside faster and better informed
• Use all available information - the notes, the drug chart, the observation trend, and anyone who knows the patient, in parallel with your examination

Airway

The airway is assessed and secured first because nothing else matters if it is not patent. Look, listen and feel: look for chest and abdominal movement and use of accessory muscles, listen for added sounds at the mouth, and feel for air movement at the mouth and nose.

Immediate management

• Head tilt-chin lift to open the airway, or jaw thrust if cervical spine injury is suspected
• Suction under direct vision to clear blood, vomit or secretions
• Simple adjuncts - an oropharyngeal (Guedel) airway in the unconscious patient without a gag reflex, or a nasopharyngeal airway if some gag reflex remains or the jaw is clenched
• Call for anaesthetic help early if simple measures do not secure the airway - do not persist alone with a failing airway
• Apply high-flow oxygen (15 L/min via non-rebreathe mask) once the airway is open, pending formal titration

Breathing

Once the airway is patent, assess breathing. Expose the chest, and look, listen, feel and count.

• Look: respiratory rate, depth and symmetry of chest movement, use of accessory muscles, cyanosis, tracheal position, chest wall deformity or wounds
• Listen: auscultate all lung zones for air entry, wheeze, crackles or a pleural rub; listen for stridor before the stethoscope even reaches the chest
• Feel: chest expansion, tactile vocal fremitus, surgical emphysema, and percuss for dullness (effusion, consolidation) or hyperresonance (pneumothorax)
• Measure: respiratory rate, oxygen saturations, and consider an arterial blood gas if the picture is unclear or the patient is hypoxaemic

Oxygen delivery devices

The device you choose depends on how much oxygen the patient needs and how precisely you need to control it. In an emergency, start with the device that delivers the most oxygen and step down once the patient is stable and a target range is set.

Immediate management

• Oxygen titrated to target saturations - 94-98% for most patients, 88-92% for those at risk of hypercapnic respiratory failure (for example known COPD)
• Needle decompression for a suspected tension pneumothorax, followed by chest drain insertion
• Nebulised bronchodilators for wheeze suggesting bronchospasm
• Support ventilation with bag-valve-mask if respiratory effort is inadequate, and escalate early for consideration of non-invasive or invasive ventilation
• Arterial blood gas to quantify oxygenation, ventilation (CO2) and acid-base status

Circulation

Assess perfusion at the bedside before reaching for a monitor. Skin colour and temperature, capillary refill time (centrally, at the sternum, should be under 2 seconds), and pulse rate, rhythm and volume all give an immediate read on circulatory status.

• Look: skin colour, sweating, distended neck veins, visible bleeding
• Feel: peripheral and central pulses for rate, rhythm and volume; capillary refill time; skin temperature
• Measure: blood pressure, continuous ECG monitoring, urine output if catheterised
• Look for and control external haemorrhage with direct pressure before anything else in circulation

Immediate management

• Gain IV access - two large-bore (14-16G) cannulae in the antecubital fossae if possible
• Send bloods at the same time as cannulation - FBC, U&E, LFTs, CRP, clotting, group and save (or crossmatch if bleeding), venous or arterial lactate, and blood cultures if sepsis is suspected
• Fluid bolus - typically 500 mL of balanced crystalloid over 15 minutes for hypotension or other signs of shock, reassessing after each bolus (see ²)
• Control haemorrhage - direct pressure, tourniquet or haemostatic dressing for external bleeding; activate the major haemorrhage protocol if bleeding is severe
• Treat the underlying cause in parallel - antibiotics for suspected sepsis, blood products for haemorrhage, thrombolysis or PCI for STEMI

Classifying shock

Shock is circulatory failure resulting in inadequate tissue perfusion. Identifying the type early narrows the differential and directs treatment, since the fluid a hypovolaemic patient needs can harm a cardiogenic one.

Disability

Disability is a rapid neurological assessment, plus the bedside test that most often explains a depressed conscious level: blood glucose.

• Conscious level - AVPU (Alert, responds to Voice, responds to Pain, Unresponsive) for a rapid screen, or the Glasgow Coma Scale for a fuller assessment, particularly after head injury
• Pupils - size, symmetry and reactivity to light
• Blood glucose - always check; hypoglycaemia is rapidly reversible and easily missed
• Focal neurology - limb weakness, facial asymmetry, plantar responses if a stroke or space-occupying lesion is suspected
• Pain score
• Temperature

A GCS of 8 or below signals loss of protective airway reflexes and is a standard trigger to call for anaesthetic help and reconsider the airway - this is why disability findings often send you back to A.

Exposure

Fully expose the patient to look for anything not yet found - rashes, wounds, bleeding, swelling, lines, drains, catheters and medical devices - while maintaining dignity and preventing heat loss.

• Look everywhere, including the back, axillae and skin folds - log-roll a trauma patient to inspect the spine
• Temperature - hypothermia impairs clotting and cardiac conduction; fever suggests infection
• Review all lines, drains and catheters for signs of infection, dislodgement or blockage
• Check the abdomen for distension, tenderness, guarding or a pulsatile mass
• Review the drug chart and allergy status, and check for a medical alert bracelet or similar
• Cover the patient promptly afterwards to preserve dignity and normothermia

Reassessment and escalation

ABCDE is not a single pass. Reassess after every intervention, and repeat the whole sequence from A if the patient deteriorates, a new intervention is given, or you are simply unsure. A patient who was stable five minutes ago can obstruct their airway or arrest without warning.

NEWS2

The National Early Warning Score 2 assigns points to respiratory rate, oxygen saturation, air or oxygen, systolic blood pressure, pulse rate, level of consciousness and temperature. The aggregate score standardises the language of deterioration across the NHS and triggers a defined escalation response.³

SBAR handover

When calling for help, structure the handover as SBAR so the listener has everything they need to prioritise the call and arrive prepared:

• Situation - who you are, who the patient is, and why you are calling, in one sentence
• Background - the relevant history, admission diagnosis and comorbidities
• Assessment - your ABCDE findings, observations and NEWS2 score, and what you think is going on
• Recommendation - what you want the responder to do, and how urgently

Common pitfalls

• Skipping ahead - examining circulation before confirming the airway and breathing are safe
• Treating late - completing the whole assessment before acting on an obviously life-threatening finding
• Forgetting to reassess - giving oxygen or fluid and moving on without checking the effect
• Missing disability - forgetting to check glucose in a drowsy patient, or treating agitation as confusion without checking hypoxia and glucose first
• Incomplete exposure - missing a source of sepsis or bleeding hidden by clothing or dressings
• Delayed escalation - persisting alone with a deteriorating patient instead of calling for senior help early

Red flags