In medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, hypoventilation (also known as respiratory depression) occurs when ventilation
Ventilation (physiology)
In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. It is categorized under the following definitions:-Sample values:...

 is inadequate (hypo means "below") to perform needed gas exchange
Gas exchange
Gas exchange is a process in biology where gases contained in an organism and atmosphere transfer or exchange. In human gas-exchange, gases contained in the blood of human bodies exchange with gases contained in the atmosphere. Human gas-exchange occurs in the lungs...

. By definition it causes an increased concentration of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

Hypercapnia or hypercapnea , also known as hypercarbia, is a condition where there is too much carbon dioxide in the blood...

) and respiratory acidosis
Respiratory acidosis
Respiratory acidosis is a medical condition in which decreased ventilation causes increased blood carbon dioxide concentration and decreased pH ....



It can be caused by medical conditions, such as stroke affecting the brainstem, by holding one's breath, or by drugs
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...

, typically when taken in overdose. Hypocapnia
Hypocapnia or hypocapnea also known as hypocarbia, sometimes incorrectly called acapnia, is a state of reduced carbon dioxide in the blood. Hypocapnia usually results from deep or rapid breathing, known as hyperventilation....

 also stimulates hypoventilation.


As a side effect
Adverse drug reaction
An adverse drug reaction is an expression that describes harm associated with the use of given medications at a normal dosage. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs...

 of medicines or recreational drugs, hypoventilation may become potentially life-threatening. Many different CNS depressant
A depressant, or central depressant, is a drug or endogenous compound that depresses the function or activity of a specific part of the brain...

 drugs such as alcohol
Alcoholic beverage
An alcoholic beverage is a drink containing ethanol, commonly known as alcohol. Alcoholic beverages are divided into three general classes: beers, wines, and spirits. They are legally consumed in most countries, and over 100 countries have laws regulating their production, sale, and consumption...

, benzodiazepines, barbiturates, GHB
Gamma-Hydroxybutyric acid
γ-Hydroxybutyric acid , also known as 4-hydroxybutanoic acid and sodium oxybate when used for medicinal purposes, is a naturally occurring substance found in the central nervous system, wine, beef, small citrus fruits, and almost all animals in small amounts. It is also categorized as an illegal...

, sedatives and opiates produce respiratory depression when taken in large or excessive doses; however this is most commonly seen as a cause of death with opiates or opioids, particularly when they are combined with sedatives such as alcohol or benzodiazepines. Strong opiates, (fentanyl, heroin, morphine
Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...

, etc.), barbiturates, and the benzodiazepine, temazepam
Temazepam is an intermediate-acting 3-hydroxy benzodiazepine. It is mostly prescribed for the short-term treatment of sleeplessness in patients who have difficulty maintaining sleep...

, are notorious for producing this effect; in an overdose, an individual may cease breathing entirely (go into respiratory arrest
Respiratory arrest
Respiratory arrest is the cessation of breathing. It is a medical emergency and it usually is related to or coincides with a cardiac arrest. Causes include opiate overdose, head injury, anaesthesia, tetanus, or drowning...

) which is rapidly fatal without treatment.


Respiratory stimulants such as nikethamide
Nikethamide is a stimulant which mainly affects the respiratory cycle. Widely known by its former trade name of Coramine, it was used in the mid-1900s as a medical countermeasure against tranquilizer overdoses, before the advent of endotracheal intubation and positive-pressure lung expansion...

 were traditionally used to counteract respiratory depression from CNS depressant overdose, but were of only limited effectiveness. A new respiratory stimulant drug BIMU8
BIMU-8 is a drug which acts as a 5-HT4 receptor selective agonist. BIMU-8 was one of the first compounds of this class. The main action of BIMU-8 is to increase the rate of respiration by activating an area of the brain stem known as the pre-Botzinger complex....

 is currently being investigated which seems to be significantly more effective and may be useful for counteracting the respiratory depression produced by opiates and similar drugs without offsetting their therapeutic or recreational effects.

Associated conditions

Disorders referred to as "Congenital Central Hypoventilation Syndrome" or "CCHS" and "Rapid-Onset Obesity, Hypothalamic Dysfunction, Hypoventilation, with Autonomic Dysregulation" or ROHHAD
Rapid-onset Obesity with Hypothalamic dysfunction, Hypoventilation and Autonomic Dysregulation is a very rare disease affecting approximately only 75 cases worldwide. Patients with ROHHAD, as well as patients with Congenital Central Hypoventilation Syndrome have damaged the mechanism governing...

 are recognized. CCHS condition may be a significant factor in some cases of sudden infant death syndrome
Sudden infant death syndrome
Sudden infant death syndrome is marked by the sudden death of an infant that is unexpected by medical history, and remains unexplained after a thorough forensic autopsy and a detailed death scene investigation. An infant is at the highest risk for SIDS during sleep, which is why it is sometimes...

 or SIDS, often termed "cot death" or "crib death."

The opposite condition is hyperventilation
Hyperventilation or overbreathing is the state of breathing faster or deeper than normal, causing excessive expulsion of circulating carbon dioxide. It can result from a psychological state such as a panic attack, from a physiological condition such as metabolic acidosis, can be brought about by...

 (too much ventilation), resulting in low carbon dioxide levels (hypocapnia
Hypocapnia or hypocapnea also known as hypocarbia, sometimes incorrectly called acapnia, is a state of reduced carbon dioxide in the blood. Hypocapnia usually results from deep or rapid breathing, known as hyperventilation....

), rather than hypercapnia.
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