Glossary term:

Valsalva / Valsalva-like manoeuvre

Blowing out with lips and nostrils closed, causing the ears to pop – such as we might do as an aeroplane descends from a height. We do this to drive air into the middle ear, in order to relieve the increasing cabin pressure that is bearing down upon the outside of the eardrums. If performed more vigorously, against a closed larynx (voice-box), a Valsalva manoeuvre will impede the return of blood to the heart, in the veins. The veins engorge and this back pressure is transmitted into the head and the spinal canal and, in turn, this pressure is transferred into the cerebrospinal fluid channels. Coughing, sneezing, laughing, shouting or bending over are examples of every-day actions which are accompanied by brief periods during which we involuntarily squeeze air out of our lungs with the voice-box closed.