Hyperventilation syndrome

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

In psychiatry, hyperventilation syndrome is an episodic disorder that often presents with chest pain and a tingling sensation of the fingertips (paresthesia) and around the mouth, as well as deep and labored breathing (causing hyperventilation), although chronic but subtle hyperventilation can cause these symptoms too.

Hyperventilation syndrome can be triggered by emotions of stress, anxiety, depression, or anger. Occasional hyperventilation from panic is generally related to a specific fear or phobia, such as a fear of heights, dying, or closed-in spaces (claustrophobia).

Chest radiography is usually performed to rule out any acute pulmonary or cardiac pathology. In patients with hyperventilation syndrome a chest X-ray should be normal.

In majority of cases, patients with a normal chest X-ray will not need a chest CT. The chest CT is indicated to evaluate abnormalities found on chest X-ray, such as possible pulmonary nodules or masses, parenchymal infiltrates. CT angiography (CTA) of the chest is done when pulmonary embolism needs to be ruled out.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1],Farman Khan, MD, MRCP [2]

The pathophysiology of hyperventilation syndrome can be divided into psycopathology, abnormalities of regulatory system, mechanism of pulmonary, and neurologic symptoms.

There is an association between hyperventilation syndrome and psychological conditions such as panic disorder, but whether the psychological condition is primary or secondary is often unclear. Somatic and respiratory symptoms are common in patients with psychological distress. “Disproportionate breathlessness” is associated with depression, anxiety, bereavement, and resentment.^[1]

Imbalance between sensory signals from pulmonary and chest wall stretch receptors and motor signals from the motor cortex result in feelings of dyspnea. The greater the imbalance, the greater the severity of dyspnea.^[2]

With decreasing arterial Carbon Dioxide levels (PaCO₂), cerebral blood flow decreases in a linear fashion. Raichle and Plum has shown that a decrease of 1 mmHg of PaCO₂ is associated with a 2 percent decrease in cerebral blood flow.^[3] Reduction in cerebral blood flow in the setting of hyperventilation in combination with respiratory alkalosis may explain the neurologic symptoms such as paresthesias, headache, and light-headedness. In hyperventilation syndrome, respiratory alkalosis leads to acute changes in ionized serum calcium levels, which could result in paresthesias and/or tetany.

Abnormalities in control system for ventilation, the reticular activating system, are important in the development of symptoms in some patients with hyperventilation syndrome. Under normal conditions, healthy individuals demonstrate regular breathing with no voluntary effort. Hypersensitivity of certain parts of the brain such as the hippocampus, medial prefrontal cortex, amygdala and its brain stem projections, also some times called “Fear Center,” have been associated with hyperventilation syndrome.^[4] Increased sensitivity to carbon dioxide has also been proposed as a mechanism for hyperventilation syndrome and its association with psychological symptoms. An activated hypersensitive fear network leads to increased central respiratory drive, causing low PaCO₂ levels.

HVS can occur as part of a panic attack. Despite the stigma, most patients are exaggerating symptoms but are in true distress.

Patients with HVS feel as though they cannot get enough air, but the opposite is true: they have too much oxygen and too little carbon dioxide in their blood. Hyperventilation is self-promulgating as rapid breathing causes carbon dioxide levels to continue to fall, and respiratory alkalosis (high blood pH) develops. This makes the symptoms worse, which causes the patient to try breathing even faster, perpetuating the cycle.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

• Anxiety and nervousness
• Bleeding
• Cardiac disease, such as congestive heart failure or heart attack
• Drugs (such as an aspirin overdose)
• Infection such as pneumonia or sepsis
• Ketoacidosis and similar medical conditions
• Lung disease such as asthma, chronic obstructive pulmonary disease (COPD), or pulmonary embolism
• Panic attack
• Pregnancy
• Severe pain
• Situations where there is a psychological advantage in having a sudden, dramatic illness (for example, somatization disorder)
• Stimulant use
• Stress

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], Farman Khan, MD, MRCP [2]

Many serious and emergent medical conditions can present with symptoms also found in patients with hyperventilation syndrome. The differential diagnosis of HVS is broad, and includes:^[1]

• Acute coronary syndrome
• Arrhythmia like atrial fibrillation, Atrial flutter
• Heart failure

• Hyperthyroidism
• Ketoacidosis
• Less frequently hypoglycemia or hypocalcemia

• Costochondritis

• Seizure disorder

• Asthma exacerbation
• Chronic obstructive pulmonary disease exacerbation
• Pneumonia
• Pneumothorax
• Pulmonary embolism

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], Farman Khan, MD, MRCP [2]

About 10% of patients in a general internal medicine practice have been reported to have HVS as their primary diagnosis.

The peak incidence is between the ages of 15 and 55 years, but cases have been reported in all age groups except infants.

Limited data suggest that hyperventilation syndrome is found more commonly in women than in men. Some studies have reported that the female-to-male ratio may be as high as 7:1.

The prevalence of HVS is difficult to assess accurately because of varying diagnostic criteria and its association with psychological symptoms. There is significant overlap between panic disorder, panic attacks and hyperventilation syndrome. The prevalence of hyperventilation syndrome ranges from 25 to 83 percent in patients with an anxiety disorder. HVS has been reported in up to 11 percent of the patients with non psychiatric medical comorbidities.^[1] Similarly hyperventilation syndrome has been reported in 36% asthmatic patients.^[2]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Hyperventilation syndrome can be triggered by emotions of stress, anxiety, depression, or anger. Occasional hyperventilation from panic is generally related to a specific fear or phobia, such as a fear of heights, dying, or closed-in spaces (claustrophobia).

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