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Hyperventilation syndrome 

Hyperventilation syndrome
Hyperventilation syndrome

Stephen Chapman

, Grace Robinson

, John Stradling

, Sophie West

, and John Wrightson

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date: 29 June 2022


Poorly defined, and the term is falling into disfavour, dysfunctional breathing being the alternative. Most respiratory physicians still use hyperventilation syndrome to describe breathlessness and overbreathing associated with fear, stress, and anxiety, in the absence of any demonstrable physiological abnormality.

Usually part of a spectrum of physical symptoms (e.g. chest pain, palpitations/tachycardia, fatigue, dizziness, paraesthesiae, headache, diarrhoea, inappropriate sweating, etc.) from anxiety or panic disorder. Other specialities may have been consulted due to the mixed symptomatology.


Hyperventilation syndrome can occur de novo or follow a respiratory disorder that has resolved—such as an attack of mild asthma. It appears to be based on a heightened awareness of breathing and concerns as to what the SOB signifies. The PaCO2 is intermittently low, with a respiratory alkalosis. Recordings of breathing pattern often show a rather chaotic pattern.

Clinical features

  • Intermittent episodes of breathlessness largely unrelated to exercise, although can be worsened by exercise

  • May be associated with symptoms of respiratory alkalosis, such as numbness, tingling of the extremities, feelings of impending doom, and light-headedness, occasionally to the point of losing consciousness (cerebral vasoconstriction due to the hypocapnia)

  • Sensation of not being able to take a satisfactory breath

  • No history suggestive of an alternative current respiratory disorder, although there may have been one previously

  • History of some stressful situation in the patient’s life

  • Previous episodes.


Is essentially one of exclusion, but with additional confirmatory findings.

  • No evidence of a respiratory cause, i.e. normal lung function, normal CXR, and normal SaO2 at rest and on exercise to the point of breathlessness (SaO2 may even rise on exercise)

  • No evidence of a cardiac cause for the breathlessness

  • Irregular breathing pattern at rest and on exercise (watching the patient exercise often reveals the almost instant SOB and chaotic breathing)

  • No evidence of PHT

  • No evidence to support PEs

  • No evidence of hyperthyroidism

  • Low PaCO2, raised pH on blood gases (and a normal A–a gradient)

  • No metabolic acidosis on blood gases (e.g. ketoacidosis, lactacidosis)

  • Unresolved psychological issues or social phobia/agoraphobia.

Differential diagnosis

Important pathological causes to exclude are:

  • Subtle ILD with a normal CXR: consider HRCT

  • Mild asthma with normal basic PFTs at the time of testing: consider PEFR monitoring, exercise provocation, or bronchial reactivity testing

  • PHT/thromboembolic disease: consider cardiac echo or CTPA

  • Hyperthyroidism

  • Unexpected acidosis, e.g. renal failure, lactacidosis, ketoacidosis.


It is important not to dismiss the patient’s symptoms, implying it is ‘all in the mind’. The patient has a real symptom, which requires a real explanation. There are no controlled trials of management, but most clinicians will offer an explanation based on an ‘over-awareness’ of respiratory sensations (occasioned by some previous respiratory illness), heightened by anxiety. It is important to explain that the associated symptoms of tingling and light-headedness are well recognized and harmless.

Old recommendations to rebreathe into a paper bag have not stood the test of time and are rather impractical in the middle of a supermarket. Because cold peripheries often accompany an episode (vasoconstriction), placing the cold palms on to the cheeks can help suppress the desire to breathe, thought to be related to the diving reflex: again, this is an untested remedy.

Careful and convincing explanation without over investigation may be enough, stressing the normality of the investigations. A short period on an anxiolytic (e.g. diazepam 2–5mg bd) may be helpful to demonstrate that the symptoms can be controlled. Management of the psychological problem may be possible. Some experienced respiratory physiotherapists can help patients control their symptoms and divert the anxiety away from breathing.

Failure to respond should always prompt a reconsideration of whether an underlying disorder is gradually progressing to the point where an investigation becomes abnormal. On the other hand, repeated investigations will confirm the patient’s concern that ‘the doctors think there is something wrong.’


Some patients improve quickly with explanation. Some tend to relapse at times of stress. Some prove resistant to any treatment and probably should be seen in the clinic regularly, but infrequently, to reduce their likelihood of involving other medical services with another pointless round of investigations.

Nijmegen hyperventilation score

Filled in by a patient (see Table 29.1).

Table 29.1 Example of Nijmegen hyperventilation score

Before treatment





Very often






Chest pain

Feeling tense

Blurred vision

Dizzy spells

Feeling confused

Faster/deeper breathing

Shortness of breath

Tight feeling in the chest

Bloated feeling in the stomach

Tingling fingers

Unable to breathe deeply

Stiff fingers or arms

Tight feeling around mouth

Cold hands or feet

Heart racing (palpitations)

Feeling anxious

Total score


A score of ≥22 is highly suggestive of hyperventilation syndrome.