up SearchFeedback[help] CPMCnet

T H E O R I E SI NM E D I C I N E

Panic Attacks and “Suffocation Alarm Systems”

By William Allstetter

Panic attacks result not from fear and anxiety, but from breathing abnormalities, P&S research has shown. According to a model proposed by Dr. Donald F. Klein, professor of psychiatry, people who suffer repeated panic attacks have a hypersensitive “suffocation alarm system” that triggers the shortness of breath and acute anxiety that are the hallmarks of a panic attack.

Panic attacks come on suddenly, often with a feeling of intense terror and impending doom and often for no known reason. Those symptoms are accompanied by shortness of breath, a pounding heart, dizziness, and chest pain, lasting less than 10 minutes. Reports of longer episodes require diagnostic review. Often, a person suffering a panic attack for the first time mistakes it for a heart attack and goes to the emergency room. Repeated panic attacks, known as panic disorder, can cause a person to become chronically apprehensive. People may even begin avoiding situations they fear will trigger an attack or places where they will not be able to get to help.

Panic attacks are almost always associated with shortness of breath or difficulty breathing. When people feel short of breath, they often respond by hyperventilating, another common symptom of panic attacks. People hyperventilating exhale more carbon dioxide than they produce, thereby lowering carbon dioxide levels in the body. As carbon dioxide levels drop, several other changes in the body result in the lightheadedness and dizziness that often accompany panic attacks.Man and paper bag

A common theory about panic attacks is that hyperventilation actually triggers them. The theory holds that people with panic disorder commonly hyperventilate and that a panic attack ensues when they overreact fearfully to the resulting dizziness and lightheadedness. In fact, emergency room physicians often tell people suffering panic attacks to breathe into paper bags on the theory that rebreathing exhaled, carbon dioxide-rich air will raise carbon dioxide levels in the blood and stop the panic attack.

That, however, appears to be wrong. Dr. Klein and his colleagues, Dr. Jack M. Gorman, professor of psychiatry, and Dr. Laszlo A. Papp, associate professor of clinical psychiatry, have demonstrated in several studies that acute hyperventilation fails to reliably produce panic attacks among panic disorder patients. They also found that air enriched with 5 percent carbon dioxide frequently induced panic attacks in panic disorder patients, which is exactly the opposite of the prediction of the hyperventilation theory. Dr. Klein believes that the apparently curative powers of the paper bag derive primarily from the transient nature of panic attacks; the attacks would have ended whether or not the patients breathed into a paper bag. Dr. Klein said one study indicated that the paper bag provides at most a beneficial placebo effect.

Dr. Klein realized that both carbon dioxide and sodium lactate levels rise in the brain when a person is being suffocated. He thought both lactate and carbon dioxide might be sending signals to the brain, warning of impending suffocation.

“Maybe you have an alarm system in there,” says Dr. Klein. He developed the theory that panic disorder patients have a hypersensitive “suffocation alarm system” and that the alarm is triggered by rising levels of carbon dioxide and/or sodium lactate in the brain.

Although no suffocation alarm system has, as yet, been located in the brain, the theory accounts for several other findings about panic attacks. Many panic disorder patients have chronically low levels of carbon dioxide in their blood, caused by slight hyperventilation. Dr. Klein and his colleagues interpret the slight hyperventilation as an effort by the patients to prevent triggering their sensitive suffocation alarms. Also, carbon dioxide levels rise when people move from stage 3 sleep to stage 4 sleep, which is a common time for panic attacks to begin. Female panic disorder patients commonly suffer more panic attacks during the days just before menstruation, a time when carbon dioxide levels in the body suddenly rise because of the cessation of respiratory stimulation by progesterone.

Children with Ondine’s Curse, a rare congenital disorder, provide a striking contrast to panic disorder patients. Children with this disorder breathe while awake but stop once they fall asleep. Breathing during sleep is known to be driven by carbon dioxide levels. But even when they are awakened and their bodies are severely overloaded with carbon dioxide, the children show no respiratory stimulation or particular distress. Their suffocation alarm systems appear to be non-existent.

The suffocation alarm model of panic disorder has highlighted a connection between panic and breathing. Recent papers by Drs. Klein, Gorman, and Papp have described a number of breathing abnormalities common among panic disorder patients. The model has also suggested potential new treatments for pulmonary problems. For instance, panic is a common complication in emphysema and asthma patients. Serotonin action anti-panic agents, which seem to desensitize the suffocation alarm system, may help those patients. The suffocation alarm theory also has guided researchers in developing a monkey model of panic disorder, which should help in future tests of potential anti-panic drugs.

Return to Table of Contents