An Overview of Tachypnea

Possible Causes of Rapid, Shallow Breathing

man experiencing tachypnea and holding his throat
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Tachypnea is defined as an elevated respiratory rate, or more simply, breathing that is more rapid than normal. A normal respiratory rate can vary depending on age and activity but is usually between 12 and 20 breaths per minute for a resting adult. In contrast to the term hyperpnea which refers to rapid deep breathing, tachypnea refers to rapid, shallow breathing. Let's look at the potential causes of tachypnea, as well as medical conditions in which it may occur.

Tachypnea vs Dyspnea

As noted, tachypnea is a term used to describe a rapid, shallow respiratory rate, but says nothing about what a person is feeling. With tachypnea a person may be very short of breath, or in contrast, may not notice any difficulty with breathing at all.

Dyspnea is a term that also describes breathing, but refers to the sensation of shortness of breath. Dyspnea can occur with a normal breathing rate, a high breathing rate, or a low breathing rate. It can also occur with both a shallow breathing pattern or a deep breathing pattern.

Physiological Causes

Physiological causes of a condition refer to the normal response of the body to correct another condition, In this case, the condition, such as tachypnea, is not an abnormal bodily response, but is a normal response to another type of abnormal condition or imbalance in the body. Tachypnea can be caused by two primary physiological processes:

  • An imbalance between the respiratory gasses in the body: A low oxygen level in the blood (hypoxemia) or an increased level of carbon dioxide in the blood (hypercapnia) can cause tachypnea.
  • An acid-base imbalance in the body: Tachypnea can be caused by an excess of acid in the body or a decrease in base in the body (a disruption in the acid-base balance of the body.) When the body senses that the blood is too acidic (metabolic acidosis), it blows off carbon dioxide out of the lung in an attempt to rid the body of acid.
  • Fever: A fever for any reason can cause tachypnea. With a fever, tachypnea is compensatory, meaning that breathing becomes more rapid to eliminate heat from the body.

In both of these examples, tachypnea is not abnormal, but rather a way in which the body compensates for another abnormality in the body to maintain balance (homeostasis).

Pathological Causes

In contrast to physiological causes, a pathological cause is one that does not occur in an effort to restore the balance in the body, and actually, does the opposite. For example, hyperventilation can cause rapid shallow breathing that is not occurring as an effort to restore balance in the body, but instead may be a reaction to anxiety or fear.

Conditions That May Result in Tachypnea

A wide range of medical conditions can result in tachypnea. By categories these may include:

  • Lung related: Lung diseases that result in a low level of oxygen or an elevated level of carbon dioxide in the body may include chronic obstructive pulmonary disease (COPD), asthma, pneumonia, pulmonary fibrosis, a pneumothorax (collapsed lung) or a pulmonary embolism, among others. The rapid breathing rate is the body's way of trying to increase oxygen or lower carbon dioxide levels in the blood. In people who are hospitalized, tachypnea can be a sign that pneumonia is developing, and often occurs before other obvious signs of pneumonia are present.
  • Heart-related: Conditions such as heart failure, anemia, or a low thyroid can result in cardiovascular changes which in turn cause tachypnea.
  • Hyperventilation: This may occur due to pain, anxiety, or other conditions.
  • Metabolic acidosis - When the acid level is too high in the blood, breathing rate increases to blow off carbon dioxide. Some causes of this include diabetic ketoacidosis, lactic acidosis, and hepatic encephalopathy.
  • Central nervous system-related: Tachypnea may be directly caused by brain abnormalities such as brain tumors.
  • Medications: Drugs such as aspirin, stimulants, and marijuana can cause a rapid shallow breathing rate.

Symptoms

Tachypnea may be accompanied by the sensation of shortness of breath and an inability to get enough air (dyspnea), blue-tinged fingers and lips (cyanosis) and sucking in of the chest muscles with breathing (retracting). Tachypnea may also occur without any obvious symptoms, especially when it is related to conditions such as metabolic imbalances or central nervous system conditions.

Diagnosis

The diagnosis of tachypnea will vary depending on a person's age, other medical problems, current medications, and other symptoms, but may include:

  • Oximetry: A "clip" may be placed on your finger to estimate the amount of oxygen in your blood.
  • Arterial blood gases (ABGs): Blood gases can give a more accurate estimate of your oxygen level as well as the carbon dioxide content of your blood. They will also tell your doctor the pH of your blood, which can be helpful in evaluating metabolic abnormalities. If the pH of the blood is low (acidosis), tests may be done to look for causes such as diabetic ketoacidosis, lactic acidosis, and liver problems.
  • Chest x-ray: A chest x-ray can quickly determine some causes of tachypnea, such as a collapsed lung.
  • Chest CT: A chest CT may be done to look for lung diseases or tumors.
  • Pulmonary function tests: Pulmonary function tests are very helpful when looking for conditions such as COPD and asthma.
  • Glucose: A blood sugar is often done to rule out (or confirm) diabetic ketoacidosis.
  • Electrolytes: Sodium and potassium levels are helpful in evaluating some of the causes of tachypnea.
  • Hemoglobin: A complete blood count and hemoglobin may be done to look for evidence of anemia as well as infections.
  • EKG: An EKG can look for evidence of a heart attack or abnormal heart rhythms.
  • VQ scan: A VQ scan is often done if there is a possibility of a pulmonary embolus.
  • Brain MRI: If no obvious causes of tachypnea are found, a brain MRI may be helpful in ruling out brain abnormalities (such as tumors) as a cause.
  • Toxicology screen: There are many drugs, both prescription, over-the-counter, and illegal that can cause tachypnea. A toxicology screen is often done in the emergency settings if the cause of tachypnea is unknown.

Tachypnea and Lung Cancer

Lung cancer may cause tachypnea in a number of different ways. Damage to the lungs can disrupt the normal exchange of oxygen and carbon dioxide. Scarring to the chest, such as with lung cancer surgery, may result in a decreased ability to take a breath and draw in oxygen. Chemotherapy-induced anemia can further worsen tachypnea as there are fewer red blood cells to carry oxygen, and hence breathing becomes more rapid in an attempt to correct this.

Treatments

The treatment of tachypnea depends primarily on determining and correcting the underlying cause.

Pronunciation: tak-ip-nee-uh

Examples: Sam experienced tachypnea when he went for a walk without his oxygen.

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