Do you give antivenom to all snake bites?

Snake bites are an appropriate topic for this season. We are headed into the summer when both biters and bitees are most active.

Most of us have seen a snake even if at a quivering distance. Some can tell the difference between a poisonous and non-poisonous snake. That is most important when deciding about how to treat the victim.

In North America there are two basic families of poisonous snakes: pit vipers and the coral families. Within these two families reside every snake we commonly think of that could cause us harm. Rattlesnakes, water moccasins, copperheads etc.

Death from a snake bite in this country is rare.

Usually only about 0.5% of all poisonous snakebite victims die. However, this number may be a bit incorrect as many snake bites are not reported in the U.S. and less in developing countries.
What does snake poison do?

Well, as with almost all medical questions; it depends. The venom’s effect on the body separates into three categories: Local, systemic and hematologic (the blood). Many poisonous snakes common to our area cause significant localized pain at the site of the bite. As well, local tissue breakdown or necrosis can be common along with significant swelling of the effected area. That’s the localized part.

Systemically, when the toxin reaches through the body beyond where the patient was bit it can often work as a paralytic.

This causes our patient to have weakened muscle function or even lose muscle function altogether. This last condition is usually seen in the most severe cases. Because the patient can no longer use their respiratory muscles, death will soon follow without immediate intervention. Thank goodness this is very rare.

Finally, the toxin can effect the blood by causing our vasculature to become more permeable or begin to leak blood products into the surrounding tissue. In addition, the toxin can actually cause the blood cells themselves to break apart.

Now that we are done with the gory part, what do we do?

First, we need to identify that we have been bitten by a snake. This is most commonly done by seeing one or two fang marks on the skin. Also, actually seeing a snake is very helpful in confirming that our symptom is indeed the result of a snake bite.

Next, and this is very important, calmly and slowly move our patient away from the snake. Some of the most serious snake bites are from a second “attack” when the patient didn’t initially move away from the snake.

Can we do anything while we are getting to the hospital?

The short answer is, no! All those snake kits with suction devices and cut down equipment have been shown to be ineffective and in many cases harmful.

Furthermore, placing an effected digit in ice or cold water will also make things worse.

If we are reasonably sure we have been bit by a poisonous snake get to the nearest hospital. There is one exception. If there is going to be a significant delay in medical treatment,  tie a snug (not tight nor a tourniquet) wrap around the extremity that has been bit. Make sure at least one finger can be placed under the wrapping. We do not want to cut off the blood supply — just slow the spread of localized effects to systemic effects.

We made it to the hospital how do we decide who gets anti-venom?

Anti-venom describes an old antibody that was made from horse serum. It latches onto snake toxin and rids the body of this harmful chemical. Sadly, anti-venom had some very negative outcomes, but since then we have devised a new way to make “snake” antibodies using sheep.
The common name is CroFab.The scientists who make CroFab make antibodies to most of the common type of poisonous snakes then mix them into one medicine. Then we can give one type of medicine for any poisonous snake bite.

It is estimated that up to 45 percent of all poisonous snake bites are “dry.”

No venom was delivered. For this reason and others we don’t give everyone who reports a poisonous snake bite CroFab. It is usually accepted that anyone whose symptoms are progressing should receive CroFab.

I was always taught if the swelling crosses a joint to give CroFab. So if a patient is bit on the toe and after a period of time the swelling crosses the ankle, we need CroFab. A pen can be used to draw a line around the initial area of envenomation to help medical personal determine changes in the patient’s condition. Once the first dose of CroFab is given it commits the patient to two additional doses but it can be dramatic in reducing the effects of the toxin.

So to distill all this down into something a little more straightforward. First confirm a patient has indeed been bitten by a snake. If we are able to determine whether it is poisonous all the better.
Quickly and quietly get to a safe location. In general don’t make things worse by trying to treat our patient. Get to the nearest medical facility. The doctor will observe the patient and treat supportively until determining whether CroFab is needed. The one unspoken asset is poison control. They can be and should be contacted early in the patient’s care for specialized advice to both the patient and doctor. They are the all-knowing experts of things not meant to be in the human body. Use them early. Use them often.

Enjoy the summer and all its activities but keep an eye out for our slithery friends!
Ask Dr Berry a question!
(dberry@hotmail.com)