Respiratory distress and respiratory failure: the signs !

Syndrome

The signs that breathing takes too much effort, and the ones warning that the patient is tiring out.

Updated 2026-11-01

See it in 3D: Sternocleidomastoid · Scalenes · Diaphragm · External intercostals · Rectus abdominis

What it is

Respiratory distress is a visible increase in the work of breathing; respiratory failure is the inability to keep blood oxygen up or carbon dioxide down. It is recognized first at the bedside: rate, effort, colour and mental status. Spotting the signs of exhaustion in time is one of the most important tasks of doctors and nurses.

Key findings

Being unable to say a full sentence in one breath is a simple sign of severity.
In children, expiratory grunting, head bobbing and subcostal retractions are warning signs.

Pathophysiology

Hypoxaemia from ventilation-perfusion mismatch, shunt (pneumonia, oedema, ARDS), diffusion limits or hypoventilation.
Hypercapnia from pump failure: muscle fatigue, a depressed respiratory centre, neuromuscular disease or severe obstruction.
A fatigued diaphragm stops descending and is sucked up into the chest by negative pressure: the abdomen sinks on inspiration.
The adrenergic response to hypoxaemia causes tachycardia, sweating and restlessness.

Inspection	Palpation (fremitus)	Percussion	Auscultation
Distress: tachypnea, retractions, nasal flaring, accessory muscles, tripod	Palpable scalene and sternocleidomastoid use	Depends on the cause (dull, hyperresonant or normal)	Depends on the cause; stridor, wheezes or crackles may be heard
Exhaustion or imminent failure: paradoxical breathing, bradypnea, drowsiness, cyanosis	Poor expansion	Depends on the cause	Very faint breath sounds or a silent chest

Common causes

Severe pneumonia and acute respiratory distress syndrome (ARDS).
Severe asthma attack and COPD exacerbation.
Cardiogenic pulmonary oedema.
Pneumothorax, pulmonary embolism.
Upper airway obstruction (croup, foreign body, anaphylaxis).
Respiratory depression from drugs or neuromuscular disease.

Tests that confirm it

Continuous pulse oximetry.
Arterial blood gases: oxygen pressure, CO2 pressure and pH define the type of failure.
Chest radiograph and lung ultrasound for the cause.

Test yourself

Think of the answer, then tap the question to see it.

Which blood gas value defines hypoxaemic respiratory failure?

An arterial oxygen pressure under 60 mmHg on room air.

Which inspection sign shows diaphragm fatigue?

Paradoxical breathing: the abdomen moves in on inspiration instead of out.

Why can a falling respiratory rate be a bad sign?

In a patient who is still very ill, bradypnea may mean exhaustion or CO2 narcosis, not improvement.

What limits pulse oximetry in hypercapnic failure?

It measures oxygenation, not ventilation; a patient on supplemental oxygen can saturate well with a very high CO2.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Respiratory Failure | Lung Disease | Lung Problems | MedlinePlus (MedlinePlus, U.S. National Library of Medicine, 2024); Breathing difficulty: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2024); Asthma: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2024).

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Representative model, for educational purposes only.