In medicine, hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate (hypo meaning "below") to perform needed gas exchange. By definition it causes an increased concentration of carbon dioxide (hypercapnia) and respiratory acidosis.
It can be caused by medical conditions, such as stroke affecting the brainstem, by holding one's breath, like during hypoventilation training, or by drugs, typically when taken in overdose. Hypocapnia stimulates hypoventilation. Hypoventilation may also occur in chronic mountain sickness to conserve energy.
As a side effect of medicines or recreational drugs, hypoventilation may become potentially life-threatening. Many different central nervous system (CNS) depressant drugs such as ethanol, benzodiazepines, barbiturates, GHB, 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, etc.), barbiturates, and the benzodiazepine, temazepam, are notorious for producing this effect; in an overdose, an individual may cease breathing entirely (go into respiratory arrest) which is rapidly fatal without treatment.
Respiratory stimulants such as nikethamide were traditionally used to counteract respiratory depression from CNS depressant overdose, but were of only limited effectiveness. A new respiratory stimulant drug called BIMU8 is 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 effects.
If the respiratory depression is from opioid overdose, then the overdose itself is usually treated with an inverse agonist, most likely naloxone, which will itself almost instantaneously stop the respiratory depression if caused by an opioid (and also, depending on the dose, plunge the patient into precipitated withdrawal).
Disorders like Congenital Central Hypoventilation Syndrome (CCHS) and Rapid-Onset Obesity, Hypothalamic Dysfunction, Hypoventilation, with Autonomic Dysregulation (ROHHAD) are recognized as conditions that are associated with hypoventilation. CCHS may be a significant factor in some cases of sudden infant death syndrome (SIDS), often termed "cot death" or "crib death".
- "hypoventilation" at Dorland's Medical Dictionary
- Woorons, Xavier, Hypoventilation training, push your limits! Arpeh, 2014, 164p. (ISBN 978-2-9546040-1-5)
- Zubieta-Calleja, GR; Paulev, PE; Zubieta-Calleja, L; Zubieta-Calleja, N; Zubieta-Castillo, G (September 2006). "Hypoventilation in chronic mountain sickness: a mechanism to preserve energy.". Journal of Physiology and Pharmacology: An Official Journal of the Polish Physiological Society. 57 Suppl 4: 425–30. PMID 17072073.