| Snake Bite
 When spring and summer is approaching it is a time to keep
an eye out for snakes. As the warmer months approach snakes become more active.
Snake Facts & Fiction
Nearly all Australian snakes are shy and will avoid contact with
people if at all possible. They will only attack a human if frightened, cornered or
provoked. Some of them will attack with great ferocity. The Death Adder may be the only
variation from this rule, it will make little effort to
avoid humans. If you approach a Death Adder too closely it will attack as a means of
defence.
Much has been written about how fast snakes travel and how quickly
they strike. A snake can travel no faster than about 10kph and even this is probably
exaggerated. The speed of a strike is an illusion. A trained boxer can deliver a blow as
fast as a snake, however, generally a snake’s reaction time is so much quicker than
that of a human.
Tales about snake attacks are ominous in Australia and often are accompanied by reports
that the victim dies within 30 minutes. It is extremely rare for a snake bite victim to
die under five (5) hours.
Signs & Symptoms
The bite site is usually painless. It may have
classical paired fang marks, but this is not the most common picture. Often there are just
a few lacerations or scratches, and sometimes these may be painless or go unnoticed.
Bruising, bleeding, and local swelling may be present, but significant local tissue
destruction is uncommon in Australia.
The usual sequence of systemic symptom development is as follows,
however it may vary dramatically:
<1hr: Headache (an important symptom), irritability,
photophobia, nausea, vomiting, diarrhoea, confusion; coagulation abnormalities;
occasionally sudden hypotension with loss of consciousness.
1-3hrs: Cranial nerve paralysis (ptosis, diplopia, dysphagia
etc), abdominal pain, haemoglobinuria, hypertension, tachycardia, haemorrhage.
>3hrs: Limb and respiratory muscle paralysis leading to
respiratory failure, peripheral circulatory failure with pallor and cyanosis,
myoglobinuria, eventually death .
Treatment of Suspected Snake
bites:
The steps for snake bite are
as follows;
Do not wash the bitten area.
- Snake venom cannot penetrate intact skin and any
residue around the site of the bite can be tested to identify the type of snake.
Stop Lymphatic Spread
- A 75 mm or 100 mm bandage (preferably heavy weight
crepe) is applied directly over the site of the bite about as firm as would be applied to
a strained ankle.
- The bandage is then continued up the full length of
the limb at that same pressure and back again until the whole limb is covered. The number
of bandages required will depend on the size of the limb affected.
- It is considered that the bandaging should progress
from the site of the bite towards the heart. The reason for this is that the progressive
pressure of the bandage will tend to empty veins, thus making the limb more comfortable.
It is extremely unlikely that any venom will be forced through the tissues ahead of the
bandage.
- Over 95% of all snake bites are to the limbs (75% to
the legs) which allows for the effective treatment by this method. Should a bite occur on
the trunk, constrictive bandaging is not recommended as it could restrict the patients
breathing and breathing difficulties are usually one of the symptoms observed. You should
physically apply pressure to the site of the bite with a fairly large pad and transport
the patient without delay while constantly maintaining this pressure.
Keep Immobilised
- The limb should then be immobilised by the
application of a splint. This is most important as any muscle contractions during movement
will hasten the spread of venom by the pumping action of the muscle.
Reassurance
- Reassure the patient and arrange for transport to be
brought to them to avoid any unnecessary muscle movement.
Wait for Medical Assistance
- If possible advise the doctor or hospital of the
impending arrival and transport the patient safely and without panic to medical aid. It is
most important that the driver is aware that once constrictive bandages have been
correctly applied the patient should be out of immediate danger from the snake bite. It is
foolhardy to drive recklessly and place the lives of the patient and others at risk from a
car accident. By the same token all unnecessary delays should be avoided.
- Under no circumstances should the bandage be
released until the appropriate medical facilities have been prepared and the patient is
under the care of a medical practitioner. This is because urgent treatment may be
necessary if the patient deteriorates when the bandage is released. Once the bandage is
released it allows the trapped venom to suddenly progress unhindered and this can result
in what is termed "Toxic Shock", thus the need to have trained medical
assistance present at the time.
References: Snakes, Snakebite and You Revised BK
Paterson
Acknowledgments:
Dr Straun Sutherland – Commonwealth Serum Lboratories
Dr David Smith - Division of Workplace Health & Safety. |
