Bma Illustrated Medical Dictionary

pressure changes can rupture the ear-

drum (see eardrum, perforated).

Barotrauma can be avoided by vigor-

ous swallowing or by forcibly breathing

out with the mouth closed and the nose

pinched (the Valsalva manoeuvre). This

action equalizes the internal and exter-

nal pressures in the middle ear and

sinuses. If the eustachian tubes are

blocked, as commonly occurs with a cold,

use of a nasal spray containing a decon-

gestant drugis recommended shortly

before the descent of the aircraft.

Infants should be breast- or bottle-fed

during descent to encourage swallow-

ing. (See also aviation medicine.)

barrier creamA cream used to protect

the skin against the effects of irritant

substances and of excessive exposure

to water. (See also sunscreens.)

barrier methodA method of prevent-

ing pregnancy by blocking the passage

of sperm to the uterus, for example by

using a condom or a diaphragm. (See

also contraception,barrier methods of.)

barrier nursingThe nursing technique

by which a patient with an infectious

disease is prevented from infecting

cause constipation. Therefore, it is im-

portant to have a high-fibre diet and

drink plenty of water after a barium

examination, until all the barium has

passed through.

barotraumaDamage or pain, mainly af-

fecting the middle earand facial sinuses,

that is caused by changes in surround-

ing air pressure. Air travellers are at the

greatest risk, but scuba divers face simi-

lar problems (see scuba-diving medicine).

Aircraft cabin pressure decreases as

the plane ascends and increases as it

descends. As the aircraft ascends, the

ears may “pop” as the air in the middle

ear expands and is expelled via the eus-

tachian tubes, which connect the

middle ear to the back of the throat. On

descent, the higher pressure may push

the eardrum inwards and cause pain.

Minor pressure damage in the middle

ear may cause pain, hearing loss, and

tinnitusfor a few days; damage within

the facial sinuses may also cause pain,

and possibly a discharge of mucus or

blood. Symptoms usually wear off with-

in hours or days, but treatment may be

needed if they worsen or persist. Large

BARIUM X-RAY EXAMINATIONS

Monitor

showing

barium in the

oesophagus

BAROTRAUMA BARRIER NURSING

B

X-ray machine takes

a series of pictures

BARIUM SWALLOW

Patient drinks

a solution of

barium