[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Clinical exam](https://durgical.com/en/clinical-exam/) › [Respiratory system](https://durgical.com/en/clinical-exam/#a-respiratory) › Respiratory distress and respiratory failure: the signs

[Clinical exam](https://durgical.com/en/clinical-exam/) · [Respiratory system](https://durgical.com/en/clinical-exam/#a-respiratory)

# 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](https://durgical.com/en/anatomy/sternocleidomastoid-muscle/) · [Scalenes](https://durgical.com/en/anatomy/scalenus-anterior-muscle/) · [Diaphragm](https://durgical.com/en/anatomy/diaphragm/) · [External intercostals](https://durgical.com/en/anatomy/external-intercostal-muscles/) · [Rectus abdominis](https://durgical.com/en/anatomy/rectus-abdominis-muscle/)

## Key points

- Signs of increased work: tachypnea, accessory muscles, retractions, nasal flaring, tripod position, broken sentences.
- Signs of exhaustion: paradoxical breathing, bradypnea, silent chest, drowsiness or confusion.
- Hypoxaemic failure: arterial oxygen pressure under 60 mmHg; hypercapnic: CO2 pressure over 45 to 50 mmHg with acidic pH.
- Hypercapnia: drowsiness, headache, asterixis, warm skin; hypoxaemia: restlessness, tachycardia, cyanosis.
- Cyanosis is late and may be absent in anaemia; oxygen saturation helps but does not measure ventilation.
- Nursing: report at once a rising rate, falling saturation or a change in consciousness.

## 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](https://durgical.com/en/conditions/acute-respiratory-failure/) | 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](https://durgical.com/en/conditions/acute-respiratory-failure/) | 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.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/clinical-exam/respiratory-distress-and-respiratory-failure-the-signs/)

## See it in 3D

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

- [Sternocleidomastoid](https://durgical.com/en/anatomy/sternocleidomastoid-muscle/)
- [Scalenes](https://durgical.com/en/anatomy/scalenus-anterior-muscle/)
- [Diaphragm](https://durgical.com/en/anatomy/diaphragm/)
- [External intercostals](https://durgical.com/en/anatomy/external-intercostal-muscles/)
- [Rectus abdominis](https://durgical.com/en/anatomy/rectus-abdominis-muscle/)

## Related

- [Respiratory rate and breathing patterns](https://durgical.com/en/clinical-exam/respiratory-rate-and-breathing-patterns/)
- [Pulse oximetry](https://durgical.com/en/clinical-exam/pulse-oximetry/)
- [Chest inspection: shape, expansion, accessory muscles and retractions](https://durgical.com/en/clinical-exam/chest-inspection-shape-expansion-accessory-muscles-and-retractions/)
- [Pallor, cyanosis and jaundice](https://durgical.com/en/clinical-exam/pallor-cyanosis-and-jaundice/)
- [Early warning scores: NEWS2 and qSOFA](https://durgical.com/en/clinical-exam/early-warning-scores-news2-and-qsofa/)
- [Level of consciousness and the Glasgow Coma Scale](https://durgical.com/en/clinical-exam/level-of-consciousness-and-the-glasgow-coma-scale/)

## Related conditions

- [Acute respiratory failure (hypoxaemic and hypercapnic)](https://durgical.com/en/conditions/acute-respiratory-failure/)
- [Acute respiratory distress syndrome (ARDS)](https://durgical.com/en/conditions/acute-respiratory-distress-syndrome/)
- [Asthma](https://durgical.com/en/conditions/asthma/)
- [Chronic obstructive pulmonary disease (COPD)](https://durgical.com/en/conditions/chronic-obstructive-pulmonary-disease/)
- [Community-acquired pneumonia](https://durgical.com/en/conditions/community-acquired-pneumonia/)
- [Pneumothorax](https://durgical.com/en/conditions/pneumothorax/)
- [Croup (laryngotracheobronchitis)](https://durgical.com/en/conditions/croup/)
- [Respiratory acidosis](https://durgical.com/en/conditions/respiratory-acidosis/)

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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](https://medlineplus.gov/respiratoryfailure.html) (MedlinePlus, U.S. National Library of Medicine, 2024); [Breathing difficulty: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003075.htm) (MedlinePlus, U.S. National Library of Medicine, 2024); [Asthma: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000141.htm) (MedlinePlus, U.S. National Library of Medicine, 2024).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/clinical-exam/respiratory-distress-and-respiratory-failure-the-signs/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/clinical-exam/respiratory-distress-and-respiratory-failure-the-signs/