Apnea vs Dyspnea

Respiratory difficulties can manifest in various different manners depending on the trigger. Difficulty in breathing or subjective air-hunger is termed as dyspnea while cessation of external breathing is called as apnea. Dyspnea is most often a physiological response of the body to an elevated carbon dioxide level in the blood while apnea is never physiological. Apnea can be voluntarily induced as in case of trained deep sea divers.

Apnea affects only the physical process of inhalation and exhalation without affecting cellular exchange of gases. The causes of apnea range from sleep apnea, strangulation/choking, opium toxicity to neurological diseases and mechanical trauma to any of the breathing apparatus. Normally, an untrained human being cannot sustain apnea longer than 3 minutes without risking permanent brain damage. Dyspnea most commonly occurs due to cardiovascular or respiratory diseases like anaemia, pneumonia, pneumothorax, pulmonary edema, congestive cardiac failure, heart attack, asthma, etc. Dyspnea can also occur due to overexertion like jogging or heaving a heavy weight. Dyspnea sometimes also occurs due to psychological causes like anxiety attack.

Signs and symptoms of apnea is loss of chest movements which are seen when a person inhales/exhales normally. The symptom of dyspnea is a subjective sensation of shortness of breath. It may not be confirmable by an observer as it is an individual sensation. It may be accompanied with sweating, trembling and an elevated/reduced blood pressure.

The cause of apnea needs to be identified by conducting a series of tests assessing the cardiovascular, neurological, respiratory systems of the body. An apnea-measuring device is usually used to diagnose sleep apnea. It records the number of time the patient’s breathing stops each hour over the night. Since dyspnea is a symptom of an underlying condition, tests need to be done to identify the cause of dyspnea based on other accompanying symptoms. For example in a suspected heart attack, an ECG and Troponin I test should be done while in case of pulmonary edema a chest x-ray is a must. Thus, usually a battery of tests is advised by the physician when a patient presents with acute dyspnea to find out the exact cause.

Treatment for apnea is eradication of the underlying cause. In cases of sleep apnea, devices like bi-pap (bi-phasic positive airway pressure) or c-pap (continuous positive airway pressure) might be advised to relieve the apnea during sleep. Treatment for dyspnea is for the underlying cause. Generally, oxygen might be initiated if the dyspnea is severe along with medications to tackle the actual causative condition.

Prognosis for apnea is generally fair but depends on the cause. In case of neurological conditions which are refractory to treatment, palliation using a bi-pap/c-pap might be the only alternative while if the apnea is due to drug-toxicity, then might be reversible. Prognosis of acute dyspnea is good if detected early and treated adequately. Long-standing dyspnea might become refractory to treatment and patients might need continuous oxygen supply or even a ventilator.

Take Home Pointers:

Apnea is complete cessation of the external breathing cycle of inhalation and exhalation. Dyspnea is a subjective sensation of shortness of breath.
Apnea can be induced voluntarily but is most commonly a result of a medical condition. Dyspnea can be due to psychological, pathological or physiological causes.
Diagnosis of apnea can be done using a ……. device while dyspnoea cannot always be confirmed.
Both apnea and dyspnea are mere symptoms of an underlying condition which needs to be identified by tests.
Treatment of both apnea and dyspnea is to tackle the underlying cause.

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