People sometimes breathe more rapidly or deeper than they normally do, often not in a conscious manner, as when they are tense, nervous or scared. This act of hyperventilation is acute or sudden and may last only for a brief period until one is able to relax. Prolonged hyperventilation, however, can cause a decrease in the amount of carbon dioxide (CO2) in the blood, which can make one feel dizzy or lightheaded, short of breath, and anxious. It can also cause the heart to beat rapidly and can lead to tingling in the hands or feet and fainting.
Other causes of acute hyperventilation include fever, intense exercise, emotional stress, head injury, pregnancy, and climbing very high elevations. Hyperventilation most often occurs in people who are nervous or tense, those who breathe shallowly, and in those who have other health conditions, such as panic disorder or chronic lung disease. Women tend to experience hyperventilation more often, but it can affect anyone at any age.
Hyperventilation is a common cause why people are brought to the emergency department because its presentation may resemble one who is having a heart attack, a seizure or some other medical problem. Although many doctors can easily recognize an acute episode of hyperventilation, they are less likely to diagnose chronic hyperventilation syndrome (HVS).
HVS is typically defined as a condition where the minute ventilation exceeds one's metabolic demands, which results in chemical changes in the body that produce various symptoms. This simply means that you are breathing at a rate and depth to a point that is in excess of what your body normally needs. This changes the composition of your blood gases and affects the way your body responds. One of the significant effects is a decrease in the partial pressure of carbon dioxide in your arterial blood (PaCO2) and an increase in blood pH (a measure of acidity), which are mainly associated with the characteristic symptoms of hyperventilation.
The diagnosis of chronic HVS is not as easy as acute hyperventilation because many patients with HVS may not have a marked decrease in PaCO2 during attacks. Sometimes, hyperventilation is not even clinically apparent. In many cases, patients with HVS undergo extensive medical tests and are misdiagnosed with different conditions. About two thirds of these patients have a persistently, but slightly low PaCO2 with a near-normal pH level. They usually present with chest pain and shortness of breath, as well as symptoms of central nervous system disturbance like faintness, dizziness, and impairment of memory and concentration.
Other signs and symptoms include:
- profuse sweating
- numbness/tingling and coldness of face, fingers, and feet
- muscle and joint pains
- cough, shortness of breath, chest tightness
- sighing, excessive yawning
- mouth dryness
- trouble swallowing
- belching, bloating and flatulence
- upper abdominal pain
- anxiety, tension, or inappropriate pseudocalmness
- generalized weakness
- sleep disturbances
Many patients and doctors are often misled by the symptoms that suggest serious heart disease or other chronic illnesses. However, further investigation will reveal normal findings. This has led some experts to suggest a better term for this condition such as behavioral breathlessness, with hyperventilation as a consequence, rather than the cause of the patient's condition. Many of its symptoms overlap with a psychiatric condition called panic disorder, and it is estimated that about half of all patients with panic disorder have HVS, while about 25 percent of patients with HVS have panic disorder.
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