In
medicineMedicine is the art and science of healing. It encompasses a range 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
ventilationIn respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. It is categorised under the following definitions:-Sample values:-External links:* at rtcorner.net...
is inadequate (
hypo means "below") to perform needed
gas exchangeGas exchange or respiration takes place at a respiratory surface—a boundary between the external environment and the interior of the body. For unicellular organisms the respiratory surface is governed by Fick's law, which determines that respiratory surfaces must have:*a large surface area*a thin...
. By definition it causes an increased concentration of
carbon dioxideCarbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...
(
hypercapniaHypercapnia or hypercapnea , also known as hypercarbia, is a condition where there is too much carbon dioxide in the blood...
) and
respiratory acidosisRespiratory acidosis is a medical condition in which decreased respiration causes increased blood carbon dioxide and decreased pH ....
.
It can be caused by medical conditions, such as stroke affecting the brain stem, by holding one's breath, or by
drugsA 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.
As a
side effectAn adverse drug reaction is an expression that describes harm associated with the use of given medications at a normal dose. The meaning of this expression differs from the meaning of "side effect", as this last expression might also imply that the effects can be beneficial...
of medicines or recreational drugs, hypoventilation may become potentially life-threatening.
In
medicineMedicine is the art and science of healing. It encompasses a range 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
ventilationIn respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. It is categorised under the following definitions:-Sample values:-External links:* at rtcorner.net...
is inadequate (
hypo means "below") to perform needed
gas exchangeGas exchange or respiration takes place at a respiratory surface—a boundary between the external environment and the interior of the body. For unicellular organisms the respiratory surface is governed by Fick's law, which determines that respiratory surfaces must have:*a large surface area*a thin...
. By definition it causes an increased concentration of
carbon dioxideCarbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...
(
hypercapniaHypercapnia or hypercapnea , also known as hypercarbia, is a condition where there is too much carbon dioxide in the blood...
) and
respiratory acidosisRespiratory acidosis is a medical condition in which decreased respiration causes increased blood carbon dioxide and decreased pH ....
.
Causes
It can be caused by medical conditions, such as stroke affecting the brain stem, by holding one's breath, or by
drugsA 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.
Effects
As a
side effectAn adverse drug reaction is an expression that describes harm associated with the use of given medications at a normal dose. The meaning of this expression differs from the meaning of "side effect", as this last expression might also imply that the effects can be beneficial...
of medicines or recreational drugs, hypoventilation may become potentially life-threatening. Many different CNS
depressantDepressants are psychoactive drugs which temporarily diminish the function or activity of a specific part of the body or mind. Examples of these kinds of effects may include anxiolysis, sedation, and hypotension. Due to their effects typically having a "down" quality to them, depressants are also...
drugs such as
alcoholAn alcoholic beverage is a drink that contains ethanol . Alcoholic beverages are divided into three general classes: beers, wines, and spirits....
, benzodiazepines, barbiturates,
GHBγ-Hydroxybutyric acid , also known as 4-hydroxybutanoic acid and sodium oxybate, 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 a neuroprotective therapeutic nutrient that is...
, 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, (
fentanylFentanyl — brand names include Actiq, Duragesic, Fentora, Onsolis, Sublimaze and Instanyl — is a synthetic primary μ-opioid agonist commonly used to treat chronic breakthrough pain and is commonly used pre-procedures...
,
heroinHeroin, or diacetylmorphine , also known as diamorphine , is a semi-synthetic opioid drug synthesized from morphine, a derivative of the opium poppy. It is the 3,6-diacetyl ester of morphine...
,
morphineMorphine is a highly potent opiate analgesic psychoactive drug, is the principal active ingredient in Papaver somniferum , is considered to be the prototypical opioid. Like other opioids, e.g...
, etc), barbiturates, and the benzodiazepine,
temazepamTemazepam is an intermediate-acting 3-hydroxy benzodiazepine. It is generally prescribed for the short-term treatment of sleeplessness in patients who have difficulty maintaining sleep. Temazepam is not effective for induction of sleep...
, are notorious for producing this effect; in an overdose, an individual may cease breathing entirely (go into
respiratory arrestRespiratory 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 or drowning...
) which is rapidly fatal without treatment.
Treatment
Respiratory stimulants such as
nikethamideNikethamide 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
BIMU8BIMU-8 is a drug which acts as a 5-HT
4 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.- Use :The most obvious...
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__INDEX__Rapid-onset Obesity with Hypothalamic dysfunction, Hypoventilation and Autonomic Dysregulation is a very rare disease affecting approximately only 35 cases worldwide. Patients with ROHHAD,as well as patients with Congenital Central Hypoventilation Syndrome, , have damaged the mechanism...
are recognized. CCHS condition may be a significant factor in some cases of
sudden infant death syndromeSudden infant death syndrome or crib death is a syndrome marked by the sudden death of an infant that is unexpected by history and remains unexplained after a thorough forensic autopsy and a detailed death scene investigation...
or SIDS, often termed "cot death" or "crib death."
The opposite condition is
hyperventilationIn medicine, hyperventilation is the state of breathing faster and/or deeper than necessary, bringing about lightheadedness and other undesirable symptoms often associated with panic attacks...
(too much ventilation), resulting in low carbon dioxide levels (
hypocapniaHypocapnia 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.