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[Physiology](https://durgical.com/en/physiology/) · [Respiratory](https://durgical.com/en/physiology/#s-resp)

# Abnormal breathing patterns and sleep apnea

- Regulation
- Exam priority: medium

How someone breathes says a lot: cycles that swell and fade, deep breaths from acid, or pauses in sleep each have different causes.

Updated 2026-11-01

Also called: Cheyne-Stokes, Kussmaul, Biot breathing, Obstructive sleep apnea

**See it in 3D:** [Medulla oblongata](https://durgical.com/en/anatomy/medulla-oblongata/) · [Carotid bifurcation](https://durgical.com/en/anatomy/carotid-bifurcation/) · [Nasal cavity](https://durgical.com/en/anatomy/nasal-cavity/) · [Epiglottis](https://durgical.com/en/anatomy/epiglottis/)

## Key points

- Cheyne-Stokes: crescendo–decrescendo cycles with apneas; heart failure (slow circulation) and bilateral neurological lesions.
- Kussmaul: deep, regular breathing from metabolic acidosis (diabetic ketoacidosis, uremia) that lowers PaCO₂ to compensate.
- Biot / ataxic: irregular breaths with pauses from medulla or pons injury; a poor prognostic sign.
- Obstructive apnea: effort without airflow; central apnea: no effort.
- Apnea–hypopnea index (AHI): 5–14 mild, 15–29 moderate, ≥30 severe.
- Obstructive apnea: snoring, daytime sleepiness, obesity and a thick neck; linked to hypertension and atrial fibrillation.

## What it is

Abnormal breathing patterns show where control of breathing is failing: in the chemical feedback loop, in the brainstem or in the upper airway. Cheyne-Stokes is an oscillation from delay and excess gain in the chemical loop; Kussmaul is the compensatory response to metabolic acidosis; Biot and ataxic patterns mean brainstem damage. In obstructive sleep apnea control is normal, but the pharynx collapses during sleep.

## How it works, step by step

- Breathing is set by a loop: PaCO₂ rises → chemoreceptors → more ventilation → PaCO₂ falls.
- In heart failure blood takes longer to travel from lung to chemoreceptor; the correction arrives late and overshoots.
- Hyperventilation drives PaCO₂ below the apnea threshold; breathing stops until CO₂ builds up again.
- That delay, plus highly sensitive chemoreceptors, sustains the Cheyne-Stokes oscillation.
- In metabolic acidosis H⁺ stimulates the chemoreceptors and deep ventilation lowers PaCO₂ (Kussmaul).
- In sleep the tone of the pharyngeal dilator muscles falls; a narrow airway (obesity, large tonsils) collapses.
- Obstructive apnea causes hypoxemia, hypercapnia and micro-arousals; repeated sympathetic surges raise blood pressure.

## Patterns and what they mean

| Pattern | What it looks like | Where the problem is | Example |
| --- | --- | --- | --- |
| [Cheyne-Stokes](https://durgical.com/en/conditions/heart-failure/) | Crescendo–decrescendo with apneas | Slow or unstable chemical loop | Heart failure |
| [Kussmaul](https://durgical.com/en/conditions/diabetic-ketoacidosis/) | Deep, regular, fast or normal rate | Response to metabolic acidosis | Diabetic ketoacidosis |
| Biot / ataxic | Irregular, with random pauses | Medulla and pons | Brainstem hemorrhage, raised intracranial pressure |
| [Obstructive apnea](https://durgical.com/en/conditions/obstructive-sleep-apnoea/) | Snoring, pauses with chest effort | Pharynx collapsing in sleep | Obesity, tonsillar hypertrophy |
| Opioid hypoventilation | Slow and shallow | Depressed respiratory center | Opioid overdose |

## Clinical notes

- Patient in ketoacidosis: deep breathing with a fruity odor; the low PaCO₂ is compensation, not a lung problem.
- Cheyne-Stokes in heart failure carries a worse prognosis and can improve as cardiac function is optimized.
- At altitude (Bogotá and higher) mild periodic breathing at night is common in newcomers.
- Nursing: watch the pattern for a full minute; record pauses, depth and regularity.

## Memory aid

Cheyne-Stokes rises and falls like the tide; Kussmaul blows deep to blow off the acid.

## Test yourself

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

## Why does heart failure favor Cheyne-Stokes breathing?

Low output lengthens lung-to-chemoreceptor circulation time; the PaCO₂ correction arrives late, overshoots and the cycle oscillates.

## What does a patient in ketoacidosis gain from Kussmaul breathing?

Lowering PaCO₂ limits the fall in pH: it is the respiratory compensation for metabolic acidosis.

## How is obstructive apnea told apart from central apnea on polysomnography?

In obstructive apnea chest and abdomen keep moving against a closed pharynx; in central apnea there is no respiratory effort.

## Why is obstructive sleep apnea linked to high blood pressure?

Each apnea causes hypoxemia, hypercapnia and an arousal with a sympathetic surge; repeated all night, they raise sympathetic tone by day as well.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/physiology/abnormal-breathing-patterns-and-sleep-apnea/)

## See it in 3D

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

- [Medulla oblongata](https://durgical.com/en/anatomy/medulla-oblongata/)
- [Carotid bifurcation](https://durgical.com/en/anatomy/carotid-bifurcation/)
- [Nasal cavity](https://durgical.com/en/anatomy/nasal-cavity/)
- [Epiglottis](https://durgical.com/en/anatomy/epiglottis/)

## Related topics

- [Control of breathing, chemoreceptors and lung reflexes](https://durgical.com/en/physiology/control-of-breathing-chemoreceptors-and-lung-reflexes/)
- [Metabolic acidosis, the anion gap and compensation](https://durgical.com/en/physiology/metabolic-acidosis-the-anion-gap-and-compensation/)
- [Respiratory acidosis and alkalosis](https://durgical.com/en/physiology/respiratory-acidosis-and-alkalosis/)
- [High altitude and acclimatization](https://durgical.com/en/physiology/high-altitude-and-acclimatization/)
- [Wakefulness, sleep, the EEG and seizures](https://durgical.com/en/physiology/wakefulness-sleep-the-eeg-and-seizures/)
- [Heart failure physiology](https://durgical.com/en/physiology/heart-failure-physiology/)

## Related conditions

- [Obstructive sleep apnoea](https://durgical.com/en/conditions/obstructive-sleep-apnoea/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)
- [Diabetic ketoacidosis](https://durgical.com/en/conditions/diabetic-ketoacidosis/)
- [Obesity](https://durgical.com/en/conditions/obesity/)

## In Pharmacology

- [Opioids and antagonists](https://durgical.com/en/pharmacology/classes/opioids-and-antagonists/)
- [Morphine](https://durgical.com/en/pharmacology/morphine/)
- [Naloxone](https://durgical.com/en/pharmacology/naloxone/)

[← All of physiology](https://durgical.com/en/physiology/)

Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.

Sources: [22.3 The Process of Breathing](https://openstax.org/books/anatomy-and-physiology-2e/pages/22-3-the-process-of-breathing) (OpenStax (Rice University), 2022); [Obstructive Sleep Apnea](https://www.ncbi.nlm.nih.gov/books/NBK459252/) (StatPearls (NCBI Bookshelf), 2026); [Diabetic ketoacidosis: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000320.htm) (MedlinePlus, US National Library of Medicine, 2026); [Heart Failure (Congestive Heart Failure)](https://www.ncbi.nlm.nih.gov/books/NBK430873/) (StatPearls (NCBI Bookshelf), 2026); Hall JE. Guyton and Hall Textbook of Medical Physiology, 13th ed. (ch. 42). Reference book used to check facts; its text and figures are not reproduced (Elsevier, 2016).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/physiology/abnormal-breathing-patterns-and-sleep-apnea/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/physiology/abnormal-breathing-patterns-and-sleep-apnea/