I
DROWSINESS
drip
See
intravenous infusion
.
drip, postnasal
See
postnasal drip
.
driving, health and
Safe driving depends in part on the
health of the vehicle’s driver. Any state
or medical disorder that affects a driver’s
physical condition, or impairs mental
faculties such as judgment, alertness, or
speed of reaction, increases the risk of
injury to the driver and also to other
road users and pedestrians.
One of the most obvious hazards is
being under the influence of
alcohol
.
There
are
strict
laws
regarding
the
maximum blood alcohol level allowed,
because alcohol is known to impair
judgment and to slow reaction times.
Illicit drugs
(see
drug abuse
)
have a
sim ilarly
harmful
effect.
Some
pre-
scribed
drugs
can also affect ability to
drive;
for
example,
some
antihista-
mines (used to treat disorders such as
hay fever) can cause drowsiness. The
combination of drugs and alcohol is
more potent than either used alone.
Other states
that
can
be
hazardous
include
fatigue
and any type of
stress
reaction such as anger and
anxiety
.
D ri-
ving when tired is one of the most
common causes of road accidents.
Impaired vision obviously affects a
person’s fitness to drive. Various other
health problems should be disclosed to
the driver’s vehicle licensing authority,
and
in
some
cases
may
preclude
driving for a period of time. Drivers
who have
diabetes mellitus
must inform
their vehicle licensing authority as well
as their insurance
company if they
begin
insulin
therapy. Careful m onitor-
ing of blood sugar levels is of vital
importance, because abnormally high
or low levels may im pair the person’s
judgment or cause loss of conscious-
ness. People who have had a
stroke,
or
who have had a
pacemaker
fitted, may
also be subject to driving restrictions.
Stricter regulations are in place for cer-
tain groups of drivers, for example
people with epilepsy.
Regardless of the medical condition,
it
is
extremely
important
that
the
patient contacts the vehicle licensing
authority for advice on fitness to drive
if there is the least cause for concern.
drooping eyelid
See
ptosis
.
drop attack
A brief disturbance that affects the ner-
vous system, causing a person to fall to
the ground without warning. Unlike in
fainting
,
the person may not lose con-
sciousness, but injuries can occur from
the fall. Elderly women make up the
group most commonly affected.
CAUSES
The causes are not fully understood,
but they may be a form of
transient
ischaemic attack
(TIA) in w hich there is
a fall in blood flow to nerve centres in
the
brainstem
.
Elderly men may have a
drop
attack w hile passing urine
or
w hile standing, possibly due to low
blood pressure or an abrupt alteration
in heart rhythm. Akinetic seizures (a
rare form of
epilepsy
) are also some-
times described as drop attacks; the
sufferer falls to the ground but does
not have muscular spasms.
TREATMENT
There is no treatment for drop attacks in
elderly people. Akinetic seizures usually
respond to
anticonvulsant drugs
.
drop, foot
See
foot-drop
.
dropped beat
A
type
of
cardiac
arrhythmia
(see
arrhythmia, cardiac
) characterized by the
absence of a single ventricular contrac-
tion. The next heartbeat often comes
slightly early, and is more forceful than
usual; this beat is often the one that is
noticed, rather than the dropped one.
Dropped beat is very common and may
be
caused by alcohol,
caffeine,
and
some medications. Single,
infrequent
dropped beats are very unlikely to be
due to heart disease.
dropsy
An
outmoded
term
for
generalized
oedema
(fluid accumulation in body
tissues). It is not a disease in itself, but
a sign of disease, especially of conges-
tive
heart failure
or kidney disease.
drowning
Death caused by suffocation and
hypoxia
(a
lack
of oxygen)
associated with
immersion in a fluid. Most often, the
person inhales liquid into the lungs; but
sometimes no liquid enters the lungs, a
condition
called
dry
drowning
(see
drowning, dry
) .
People who are resusci-
tated after prolonged immersion are
said to be victims of “near drowning” .
(See also
Types of drowning
,
p.246.)
MECHANISM OF DROWNING
Initially, automatic contraction of a mus-
cle at the entrance to the windpipe, a
mechanism known as the laryngeal reflex,
prevents water from entering the lungs;
instead, the water enters the oesophagus
and
stomach.
However,
the
laryngeal
reflex impairs breathing and can quickly
lead to hypoxia and to loss of conscious-
ness. If the person is buoyant at this point
and floats face-up, his or her chances of
survival are reasonable because the laryn-
geal reflex begins to relax and normal
breathing may then resume.
FIRST AID AND TREATMENT
An ambulance should be called and the
person’s condition assessed. If he or she
is not breathing and/or the pulse is
absent, resuscitative measures should be
started (see
artificial respiration
;
cardio-
pulmonary resuscitation
) and continued
until medical help arrives.
Victims can sometimes be resuscitated
despite a long period immersed in very
cold water (w hich reduces the body’s
oxygen needs). In all cases of successful
resuscitation, the person should be sent
to
hospital,
because
life-threatening
symptoms may develop some hours
after rescue if water has passed from
the lungs into the blood.
drowning, dry
A
form
of
drowning
in
w hich
no
fluid enters into the lungs. Some fatal
drowning cases are “dry” . Victims of
dry drowning have a particularly strong
laryngeal reflex, w hich diverts water
into the stomach instead of the lungs,
but at the same time impairs breathing.
As w ith cases of “wet” drowning, death
occurs by suffocation.
drowsiness
A state of consciousness between full
wakefulness and
sleep
or
unconscious-
ness
.
Drowsiness is medically significant
if a person fails to awaken after being
shaken, pinched, and shouted at, or
wakes but relapses into drowsiness.
Abnormal drowsiness must be treated
as a medical emergency. It may be the
result of a
head injury
,
high fever,
menin-
gitis
(inflammation of the membranes
surrounding the brain and spinal cord),
uraemia
(excess urea in the blood due to
kidney failure
) ,
or
liver failure
.
Alcohol or
drugs may also produce this effect. In a
person with
diabetes mellitus
, drowsi-
ness may be a result of
hypoglycaemia
(low blood sugar levels) or of
hyper-
glycaemia
(high blood sugar levels).
D
245
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