Hyperventilation syndrome
Classification and external resources
ICD-10	R06.4 or F45.33
ICD-9	306.1
DiseasesDB	31118
eMedicine	emerg/270

Hyperventilation syndrome (HVS; also Chronic Hyperventilation Syndrome or CHVS) is a respiratory disorder, psychologically or physiologically based, involving breathing too deeply or too rapidly (hyperventilation). HVS may present with chest pain and a tingling sensation in the fingertips and around the mouth (paresthesia) and may accompany a panic attack.

People with HVS feel that they cannot get enough air. In reality, they have about the same oxygenation in the arterial blood (normal values are about 98% for hemoglobin saturation) and too little carbon dioxide in their blood and other tissues. While oxygen is abundant in the bloodstream, HVS reduces effective delivery of that oxygen to vital organs due to CO₂ -induced vasoconstriction and the suppressed Bohr effect.

The hyperventilation is self-promulgating as rapid breathing causes carbon dioxide levels to fall below healthy levels, and respiratory alkalosis (high blood pH) develops. This makes the symptoms worse, which causes the person to try breathing even faster, which further exacerbates the problem.

The respiratory alkalosis leads to changes in the way the nervous system fires and leads to the paresthesia, dizziness, and perceptual changes that often accompany this condition. Other mechanisms may also be at work, and some people are physiologically more susceptible to this phenomenon than others.^[1]

Contents 1 Risk factors 2 Diagnosis 3 Prevalence in chronic disorders 4 Treatment 5 Causes 6 See also 7 References

[edit] Risk factors

Many people with panic disorder or agorophobia will experience HVS. However, most people with HVS do not have these disorders.^[1]

[edit] Diagnosis

Hyperventilation syndrome is a remarkably common cause of dizziness complaints. About 25% of patients who complain about dizziness are diagnosed with HVS.^[2] The gold-standard diagnostic technique is to have the patient breathe rapidly for two minutes. This will trigger the symptoms and convince the patient that overbreathing is responsible for the symptoms. This test can only be performed at a time when the patient is not already experiencing symptoms.

[edit] Prevalence in chronic disorders

Minute ventilation or respiratory minute volume is the volume of air which is inhaled (inhaled minute volume) or exhaled (exhaled minute volume) from a person's lungs in one minute. Medical respiratory data (see the table below) suggest that sick people breathe about 2-3 times more air at rest than the medical norm.

Condition	Minute ventilation (± standard deviation)	Number of patients	Reference
Normal breathing	6 l/min	None	Medical textbooks: [3] [4] [5] [6]
Asthma	12 l/min	101	[7]
Asthma	15 l/min	8	[8]
Asthma	14.1 (±5.7) l/min	39	[9]
Heart disease	14 (±4) l/min	88	[10]
Heart disease	12.2 (±3.3) l/min	132	[11]
Heart disease	16 (±2) l/min	11	[12]
Heart disease	15 (±4) l/min	22	[13]
Diabetes	10-20 l/min	28	[14]
Diabetes	12-17 l/min	26	[15]
Cystic fibrosis	11-14 l/min	6	[16]
Cystic fibrosis	13 (±1.8) l/min	10	[17]
COPD	12.2 (±1.9) l/min	10	[18]
Liver cirrhosis	11-18 l/min	24	[19]
Hyperthyroidism	14.9 (±0.6) l/min	42	[20]
Epilepsy	12.8 l/min	12	[21]

There are many more medical studies that found 100% prevalence of chronic hyperventilation in patients with various chronic diseases.

[edit] Treatment

A rapid traditional intervention is to have the patient breathe into a paper bag, causing rebreathing and restoration of CO₂ levels. Some physicians do not advise the paper bag rebreathing method (or limiting its use to one or two minutes) due to the possibility of inhaling too much carbon dioxide and decreasing inspired oxygen to a hypoxic patient.

The same benefits can be obtained more safely from deliberately slowing down the breathing rate by counting or looking at the second hand on a watch. This is often referred to as "7-11 breathing", because a gentle inhalation is stretched out to take 7 seconds (or counts), and the exhalation is slowed to take 11 seconds.

Most patients benefit from carefully, deliberately slowing down their breathing twice a day for five minutes at a time.^[2] The goal is to reduce breathing to no more than five breaths per minute. This helps retrain their habits and convince them that faster breathing is unnecessary.

Acupuncture has recently been proposed as a treatment.^[22]

Buteyko Method is a holistic medical breathing retraining therapy developed by Soviet Doctor Konstantin Buteyko. The goal of the therapy is to reduce minute ventilation or to breathe less, normalize the breathing pattern and restore normal breathing parameters.

[edit] Causes

Most cases are caused by anxiety or stress. However, medical conditions such as infection, blood loss, heart attack,^[23] hypocapnia or alkalosis due to chemical imbalances, decreased cerebral blood flow, and increased nerve sensitivity may also underlie this symptom.^[2]

In one study, one third of patients with HVS had "subtle but definite lung disease" that prompted them to breathe too frequently or too deeply.^[24]

[edit] See also

• Hyperventilation
• Da Costa's syndrome
• Buteyko Method (Buteyko breathing retraining method)

[edit] References