<Tr> <Th> MeSH </Th> <Td> D007040 </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <P> 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 . Hypoventilation is not synonymous with respiratory arrest, in which breathing ceases entirely and death occurs within minutes due to hypoxia and leads rapidly into complete anoxia, although both are medical emergencies . Hypoventilation can be considered a precursor to hypoxia and its lethality is attributed to hypoxia with carbon dioxide toxicity . </P> <P> Hypoventilation may be caused by: </P>

What is the relatively rare condition that can cause respiratory​ depression