What is Bradypnea?

Bradypnea is a medical term defined as abnormally slow breathing of fewer than 12 breaths per minute. It ordinarily precedes life-threatening conditions such as apnea (cessation of breathing) or respiratory arrest (breathing suddenly stops or is ineffective). Bradypnea is often caused by neurological or metabolic disorders or drug overdoses.[1]

Science of the Respiratory System

Normal breathing is an automatic, seemingly effortless event that involves expansion of the chest cage when breathing in and contraction of the chest cage when breathing out. The respiratory system’s primary roles are to provide an adequate supply of oxygen to meet the energy needs of the body and to maintain an appropriate acid/base balance by ridding the body of carbon dioxide (CO2). To accomplish this, varying volumes of air are moved in and out of the lungs at a relatively constant rate and inspiratory volume (amount of air inhaled with each breath).[2]

Precise control of normal breathing is upheld by a central respiratory pacemaker located in the medulla of the brainstem (the posterior part of the brain that connects with the spinal cord). Signals from nerve cells travel from this center through the spinal cord to the muscles of breathing. Two groups of muscles – inspiratory and expiratory – contract and relax to produce a rhythmic respiratory rate and pattern. Under normal circumstances, respiratory rate and pattern are constant and only interrupted by a larger breath or sigh every so often. When something happens to disrupt normal breathing, abnormalities may occur in respiratory rate, rhythm and effort of breathing.1

Causes of Bradypnea

bradypneaBradypnea may be caused by a wide number of health conditions including:1

  • Diabetic ketoacidosis – a serious condition that sometimes occurs in patients with severe, uncontrolled diabetes. Bradypnea arises in the late stages of this condition and may be accompanied by a decrease in arousal and awareness, fatigue, a fruity odor to the breath and abnormal, small amounts of urine output.
  • Liver failure – bradypnea may occur with end-stage liver failure and be accompanied by coma, hyperactive reflexes, hand tremors, a strong, musty smell to the breath and other late-stage symptoms.
  • Increased intracranial pressure (ICP) – bradypnea is a late sign of increased pressure on the brain and is often preceded by a decrease in arousal and awareness, deterioration of movement and coordination and dilated pupils that don’t respond to light.
  • Kidney failure – also occurring in the late stages of kidney failure, bradypnea may be associated with other late stage signs and symptoms such as a decrease in arousal and awareness, bleeding in the gastrointestinal tract, deposits of urea (waste product produced from ammonia and carbon dioxide) on the skin and other assorted symptoms.
  • Respiratory failure – a consequence of the problems that interfere with breathing, late-stage respiratory failure is usually accompanied by bradypnea, decreased breath sounds when listening to the chest with a stethoscope, rapid heart rate, slightly increased blood pressure and a decrease in arousal and awareness.
  • Drug overdose – an overdose on a class of drugs known as opioid analgesics (Vicodin, OxyContin, morphine, etc.), or less commonly, central nervous system depressants such as sedatives or barbiturates, can cause bradypnea as can combining opiates with alcohol.


The most important aspect of treatment for bradypnea is to support breathing and treat the underlying cause. For example, if the condition is caused by diabetic ketoacidosis, the patient may need to be admitted to the intensive care unit of the hospital for fluid and electrolyte replacement and insulin therapy. If the cause is related to an opioid overdose, the patient, depending upon her condition and what drugs she took, may need to have her stomach pumped, be given activated charcoal to absorb the drug or be given an opioid antagonist (drug that reverses the effects of opioid) and admitted to the hospital for further treatment and observation.[3]

For more information about bradypnea and other abnormal breathing patterns, see your primary care provider.

[1] Lippencott Williams and Wilkins. Nursing: Interpreting Signs and Symptoms. 2007.

[2] Braun SR. Respiratory Rate and Pattern. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 43.Available from: https://www.ncbi.nlm.nih.gov/books/NBK365/

[3] WebMD. Drug Overdose. Accessed March, 23, 2018.


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