Sunday, August 12, 2007

Snakes in the (Indian) Grass - The Big 4 - Dealing With Sankebites

INDIA'S "BIG FOUR"

A 'narcissistic' Indian Cobra
(Naja naja)










The Russell's Viper














Echis carinatus - the Saw Scaled Viper
Notice how variable the colouring can be.





Saranya, my daughter, did recover from a snakebite. It's part of the 'normal' risk for snake rescuers. I haven't really kept myself very up-to-date on the developments in treating snakebites for the last couple of years as my own snake rescue work has almost been non-existent (due to busyness). It's very good to see that the next generation is showing an interest in preserving these wonderful, though somewhat dangerous creatures!

Having had to brush-up on snake bites, I thought I would take the opportunity to summarise the steps to be taken when bitten by a snake...

First and foremost, no snakebite should be ignored. Most bites may be from nonpoisonous snakes and sometimes even venomous snakes do not deliver enough venom when biting to prove dangerous, but that is no excuse not to go to the nearest emergency room, get evaluated, and if necessary, have treatment started. Early treatment is the key to preventing complications, and to saving lives, limbs and kidneys!
In India, it is conservatively estimated that 20,000 to 50,000 people die annually from snakebites. Morbidity (i.e. nonfatal injury rather than mortality-death) is also significant. These are not small numbers, and there seems to have been little improvement in reducing the fatalities over the years in spite of now having good supplies of polyvalent antisnakevenom available in all population centers.

The major reason for the high mortality rate (about 10% to 15% of all those reporting bites) is the delay in getting the victim to treatment. All too often snakebite victims are sent great distances to 'big' hospitals and the delay in starting treatment is the direct cause of death.

Of course, one root cause for snake bites is that rampant human population growth has forced snakes and people to occupy the same space. In my experience many of the snakes one runs into in towns, cities and villages are nonpoisonous. Nonpoisonous snakes very commonly seen include the rat snake, water snakes, wolf snakes, trinket snakes, blind snakes, and and tree snakes like the bronze back and the lovely green vine snake. These snakes will bite when cornered but the bites should certainly not result in any serious medical problem. Clean the bite site and apply a good antiseptic such as Betadine. That's when you KNOW with absolute certainty (positive snake identification can be tricky) that the snake that bit you was nonpoisonous! The general rule (see below) with any snakebite is to take no chances and to immediately seek out professional medical help. Let the physician decide whether your bite was poisonous or not.

However, India's 'big four' are not uncommon but very surprisingly, about 80% of the venomous snakebites in India come from the small saw scaled viper (Echis carinatus), and though this is a little fellow, it can be deadly.

Snakes do not bite unless provoked, so it's probably true that a lot of the fatalities that do occur are in fact preventable. If you have a snake in your house or garden please be calm, do not approach the snake or try to drive it away, and promptly call a snake rescuer. In other words, right now get out and identify the snake rescuers in your area, store their mobile numbers well ahead of time so that you can save yourself and the snake comfortably.

Krait bites are also variable and result in little obvious pain or swelling at the site of the bite which can lead one to think that the bite was harmless - DON"T BE FOOLED - take no chances and treat every bite as potentially fatal. Some bites might even be 'dry' with the venomous snake biting but not injecting any venom. At the same time some bites can seem to be harmless but may actually have a slow start to symptoms - often Krait and saw scaled or other viper bites can have this innocent-seeming start but then turn very ugly. Just because there is no obvious pain or swelling DO NOT assume that the bite was harmeless. Treat every bite as potentially deadly till proved otherwise by the competent medical authority.

FIRST AID:
In the absence of a nearby doctor, those accompanying the bitten one need to first CALM the victim down and then immobilise the affected limb (if it is a limb). Not one of the Indian poisonous snakes brings INSTANT death. You do have time to get the victim to a hospital and treated, but do get moving immediately. If you know how to properly apply a tourniquet then do so (if the bite is on a limb).
DON'Ts:
Applying any sort of chemicals or external medicines, home remedies, nature cures, and cutting into the site of the bite to suck out the venom (was the mainstay of first aid in my youthful heyday) have all fallen out of favour.
DOs:
BE CALM >> GET MOVING TOWARDS A HOSPITAL >> CALL AHEAD FOR ANTIVENIN!

The use of pressure bandaging is controversial but if done with something like a crepe bandage after starting to move towards the nearest competent hospita, and not wound on too tightly, perhaps combined with a simple splint or sling, it may help to slow the spread of venom through the lymphatic system. The blood supply must NOT be cut off for too long! On the whole, perhaps if the bitten one will be getting to a HOSPITAL within 3 or 4 hours, it may be better not to attempt any pressure bandaging but advice on this point varies.
As you move the bitten one towards a hospital, try to gently remove any jewelery worn on the affected limb - like wrist watch, rings, bangles, bracelets, anklets, or metti (toe rings) as these may cause problems if there is subsequent swelling or edema associated with the bite. Also loosen constricting clothing like ties or belts.
Next, get the person to the nearest good hospital as fast as possible. Walking and running for the victim are to be avoided, as is movement of the affected limb. Try to carry the person at least on a pallet or makeshift stretcher if no vehicles are available.
Giving anything by mouth is best avoided except if dehydration is a risk, in which case consider sips of oral rehydration fluids (clean water mixed with a little salt and sugar will do OK).
Some poisonous snakes have cardiotoxins (poisons that can slow or stop the heart) so if possible try to keep the affected limb below the level of the heart.

The victim should be encouraged to:
Remain calm.
Move minimally.
Breathe deeply and evenly to bring the pulse rate to a steady state.

Particularly as you move towards the closest hospital, keep a watch on breathing and on keeping airways clear. If the person has difficulty breathing, first see that there is nothing blocking the airway (like the tongue, secretions, or vomit) and if necessary be prepared to help the person to breathe by doing chest compressions or mouth to mouth. Rarely will the heart be affected so early on, so full scale CPR may not be needed.
Those having cell phones should call ahead so that even if antivenom is not available, it will be made available by the time the patient arrives. remember that 10, or even more, vials of antivenom may be needed, so ask whoever is at the other end to ensure an adequate supply, OR in the absence of definite knowledge, try to take the victim to the nearest hospital. In Tamil Nadu, all the government hospitals are expected to have stock of antivenom.
Observe the snakebite victim carefully while taking them to the hospital. Note the time of the bite and its location and try to get as much accurate information on the appearance and size of the snake. Any symptoms such as discolouration at the site or of the affected limb, swelling, signs of bruising, changes in eyes (e.g. droopy lids), eyesight, speech, breathing, sweating, unusual eye movements, dizziness, bleeding, lowered level of consciousness, loss of consciousness, or other difficulties should be noted.
If the snakebite victim happens to faint the most important thing is to make sure that they are able to breathe. If possible lean the head backward and depress the tongue to keep the throat open. Do not waste time trying to make them recover from the faint. Make sure that they are breathing and concentrate on getting to the hospital fast. If, as you move towards the hospital, you do have access to a phone or mobile, ask the doctors who are waiting for you for advice particularly in case of fainting as sometimes this may indicate that a medical condition called "shock" is setting in and that is potentially more dangerous than even the effects of snake venom! It is important to keep the bite victim warm.
Try to get information on what snake it was, appearance, size, etc. but please don't waste time on this or on trying to catch the snake! Getting the person to a competent hospital is the only major priority!


TREATMENT:
Mostly, if there are symptoms, the doctors will immediately start the antivenom treatment and then one will most profitably spend one's time praying that there will be no complications. In case of allergy to the antivenin or an immune reaction the doctors will temporarily stop the antivenin, treat those symptoms, but then should proceed with administering the antivenin. Physicians should be competent at handling anaphylactic shock! - please see the PPT at the end for more details...

On admission, and at relevant intervals afterwards, doctors will probably check on how well the blood is clotting (bleeding time, clotting time, and sometimes tests like PT and aPTT), kidney function (urine output, blood urea, creatinine and electrolyte levels), and of course the vital signs - pulse, breathing, temperature, blood pressure and the amount of oxygen in the blood (pO2). They may also keep tabs on the patient's haemoglobin, blood cell counts (especially platelets), and perhaps the blood gases too.
Sometimes even after a day or two, things can go wrong with the patient starting bleeding, kidney failure, or even the heart could be affected, so keeping the victim under medical observation even after the antivenom has been administered is important. Most of the time, alert medical staff will successfully deal with each crisis as it arises.



Saranya (my daughter), was bitten by the Saw Scaled Viper (Echis, see above), but sometimes a non-big-four candidate can cause trouble.
In our our area of South India, especially in hilly areas, we do run into bites from the Hump-nosed Pit Viper (Hypnale hypnale pic. above)








or the Bamboo Pit Viper Trimeresurus gramineus




















and very, very rarely,
the King Cobra (Ophiophagus hannah).






















There have been many hits on this article as well as requests for more information so I thought I would share some of the resources that I found most helpful:
1.Snakebite Envenomation in India: A Rural Medical Emergency Indian Pediatrics 2006;43:553-554http://www.indianpediatrics.net/june2006/june-553-554.htm
2. Kraits deliver some powerful neurotoxins that cause few initial symptoms at the site of the bite but can be deadly within a couple of hours. Detailed Instructions for Krait bites can be found here: http://www-surgery.ucsd.edu/ent/DAVIDSON/Snake/Bungarus.htm *Note that Indian polyvalent antivenom is effective against Krait venom also.
3. The University of Adelaide's toxinology resources website has an excellent database of information on most of the poisonous snakes in the world, first aid, treatment, and antivenins. Use the search engine to find the information you need: http://www.toxinology.com/fusebox.cfm?fuseaction=main.snakes.search
4. Snakebite Research Unit, Little Flower HospitalAngamaly, Kerala - First Aid
http://www.lfsru.org/firstaid.htm
5.A helpful interview with Romulus Whittaker in The Hindu: http://www.hindu.com/mag/2004/06/13/stories/2004061300400200.htm
6. Guidelines for the Clinical Management of Snake bites in the South-East Asia Region http://203.90.70.117/PDS_DOCS/B0241.pdf By the WHO is now a bit dated (1999).

FOR MEDICAL PROFESSIONALS: HERE'S A GOOD PPT ON TREATING SNAKEBITE



Digg!
Post a Comment

SHARE THIS NOW

Google+ javascript:(function(){var now=new Date(),month=now.getMonth()+1;day=now.getDate();year=now.getFullYear();window.polarbear=window.polarbear||{};var D=550,A=450,C=screen.height,B=screen.width,H=Math.round((B/2)-(D/2)),G=0,F=document,E;if(C>A){G=Math.round((C/2)-(A/2))}window.polarbear.shareWin=window.open('https://www.polarbearapp.com/app','','left='+H+',top='+G+',width='+D+',height='+A+',personalbar=0,toolbar=0,scrollbars=1,resizable=1');E=F.createElement('script');E.src='//www.polarbearapp.com/js/web-bookmarklet.js?v='+month+'-'+day+'-'+year;F.getElementsByTagName('head')[0].appendChild(E)}());