Archive for January, 2009

I spotted a COBRA

Thursday, January 29th, 2009

Witnessing slithering reptiles crossing trails at MacRitchie Reservoir Park and Bukit Timah Nature Reserves happen just too often these days. The probability of seeing these creatures are high as my number of visits to the parks increase. But I definitely never expect to spot a black COBRA at my recent run at the Tampines Bike Trail.

The cobra was fully exposed on a grass patch. Its hood and forked tongue extended, clearly aware of my presence (I had two loud scream, but of course), and the snake seemed to be in no hurry to escape, as if giving me a subtle warning of its power and speed. When a friend came close to me, the cobra had already disappeared. Having a blush with a cobra is a different matter. Its bite can be deadly. Instantly, I felt that I was given a new lease of life, more so when this encounter happened on the first day of the Chinese New Year.

I cannot help but to wonder – what if I got bitten by the cobra? Will I be able to get treatment timely before the venom spread all over my nerves? Well, who would carry a snake-bite kit with them for a run here in Singapore? I don’t even have one in my expedition first aid kit.

According to a website, tens of thousands of people in Africa and in Asia are estimated to die from the bites of different cobra species every year. Farmers and plantation workers in rural parts of Asia are the most common victims. A venomous life-threatening bite may not produce symptoms immediately and observation of a bite victim is recommended for 24 hours.

Spraying (or “spitting”) venom is a defense found in a number of species of true cobras. Experiments show that the snakes deliberately aim for the eyes in humans and animals. Being struck by sprayed venom is not life-threatening. However, if the venom enters the eyes, it causes instant pain and can damage the mucus membranes and cornea, sometimes resulting in blindness.

What is important to know, and I am glad to know, is that snakes generally attack only when provoked. What is more important is that, we need to know how to provide first aid treatment while awaiting professional medical aid after a snake bites. Here we go:

The lymphatic system is responsible for systemic spread of most venoms. This can be reduced by the application of a firm bandage (as firm as you would put on a sprained ankle) over a folded pad placed over the bitten area. While firm, it should not be so tight that it stops blood flow to the limb or to congest the veins. The bitten area should be immobilized to reduce movement and the victim instructed to stay still in order to delay systemic spread of the venom. These findings were from the research done by Struan Sutherland in the 1970s and reported in medical journals (Sutherland, 1981)2. This “pressure-immobilisation” technique is currently recommended by the Australian Resuscitation Council, the Royal Australasian College of Surgeons and the Australian and New Zealand College of Anaesthetists.

If the bandages and splint have been applied correctly, they will be comfortable and may be left on for several hours. They should not be taken off until the patient has reached medical care. The treating doctor will decide when to remove the bandages. If a significant amount of venom has been injected, it may move into the blood stream very quickly when the bandages are removed. They should be left in position until appropriate antivenom and resuscitation equipment have been assembled. Bandages may be quickly reapplied if clinical deterioration occurs, and left on until antivenom therapy has been effective.

Technique
Start bandaging directly over the bitten area, ensuing that the pressure over the bite is firm and even. Do not take off any clothing as this will in the process cause movement and assist spread of the venom. If you have enough bandage you can extend towards more central parts of the body, to delay spread of any venom that has already started to move centrally. A pressure dressing should be applied even if the bite is on the victim’s trunk or torso. Immobility is best attained by application of a splint or sling, using a bandage or whatever to hand to absolutely minimise all limb movement, reassurance and immobilisation (eg, putting the patient on a stretcher). Where possible, bring transportation to the patient (rather then vice versa). Don’t allow the victim to walk or move a limb. Walking should be prevented.

Bite in the arm
Bandage as much of the arm as possible, starting at the fingers. Use a splint to the elbow. Use a sling to immobilise the arm. Do no restrict chest movement. Keep the patient still.

Bite in problem areas
Bites to the head, neck, and back are a special problem – firm pressure should be applied locally if possible.

What should not be done
DO NOT cut or excise the bitten area. DO NOT apply an arterial tourniquet. (Arterial tourniquets, which cut off the circulation to the limb, are potentially dangerous and are no longer recommended for any type of bite or sting in Australia.) DO NOT wash the bitten area if snake identification is to be attempted with venom detection kits. Removal of the bandage will be associated with rapid systemic spread. Hence ALWAYS wait until the patient is in a fully equipped medical treatment area before bandage removal is attempted.

TAKE HOME MESSAGES
The following take home messages help to rationalize our approach to snakebites and their venoms:

  • Venomous snakes often do not attack unless provoked, so leave them alone.
  • The propensity to bite varies with the species. Sea snakes are very toxic but seldom bite even when roughly handled. Vipers are aggressive and tend to bite.
  • For the rest, it is no harm to apply the pressure-immobilisation method as first aid unless one is quite sure the snake is harmless. A pressure bandaging-immobilisation first aid using the method of Prof Sutherland and adoped by the Australian Resuscitation Council helps to slow down systemic envenomation if the bite was truly venomous. The bandaging pressure to achieve is like that used in bandaging a sprained ankle. It should be firm bandaging but comfortable and can be left for some hours.
  • Thankfully, some 80% of bites from venomous snakes are dry bites containing no venom. Anyway, if uncertain, it is better to apply pressure bandage rather than not.

Alright friends, would you carry a first aid kit with you when you go for your next run in the wilderness? Bandages, we need plenty of them … :D, and perhaps a snake-bite kit too …!

Source on first aid treatment: The Singapore Family Physician Apr-Jun 2002: Vol28 – Snake Venoms by A/Prof Goh Lee Gan