Adventioneering

A Rattlesnake warning has been issued up in Canada following a series of bites in the S. Okanogan and Kamloops area. The warning was pretty useless, other than to point out that snakes exist, so here’s some thoughts;

My general experience is that the people who get bit have invited it one way or another; either from overtly mishandling live animals or by being oblivious when they go tromping around in the forest. A great way to get bit is to step over a large log, etc, where a snake is resting on the other side.

There are seven venomous snakes you are likely to encounter on the pacific coast; Crotalidae Viridis Oreganus, C. V. Helleri, C. V. Lutosus, C. Atrox, C. Ruber ruber, C. Cerastes, and C. S. Scultulatus.

Helleri, Scultulatus, and Atrox are mostly found in the southern deserts and are not really a concern to pacnw travellers. Viridis lutosus can be found in eastern Oregon.

The real threat is C. V. Oreganus, the “North Pacific Rattlesnake”. They generally grow to 40″ but may be as long as five feet, and prefer arid regions (ie, not the middle of the rainforest).

Oreganus has a particularly toxic venom which usually results in subcutaneous hemmorage. The toxin can also attack the organs, and secondary infection if edema occurs is a major risk.

Your odds are about 1:4 of not being envenomated when bit; you basically win the lottery. 61% of bites have moderate symptoms, and 11% are severe[1]. A bite with envenomation will follow with nearly instantaneous edema and severe swelling within 3-5 minutes. The bite outlook will be worse at 6-36 hours with progression of the edema. Systemic shock and organ failure becomes a risk at about 6 hours post-bite, earlier with children or bites located close to large veins or arteries (which will transfer the venom faster throughout the body).

To be on the safe side, and allowing time for medical professionals to properly evaluate the bite (they are not miracle workers), you have about a four hour window to seek supported medical care. A bite is a major medical event. If you are traveling in the back-country, any bite that develops edema is a dust-off, evac event.

If possible, you or your party members should kill and procure the snake, which will speed emergency response when you reach civilization; but do not risk another bite. This will help facilitate identification by professionals, and besides, the victim might want to make a necklace out of the fangs later. Decapitated snakes can still bite up to an hour later[2]. If capture is not possible, memorize details about the snake; particularly the rattler and the coloring features on the head.

Advice on triage varies even amongst the professional medical community. The venom circulates in the blood, so the higher the blood pressure the quicker systemic symptoms can develop. If possible the victim should not hike out; transport by vehicle, radio for assistance (If you plan on tripping a satellite beacon, know your reasonable PLB/ELB response time given the 4 hour treatment window), or send a party member out to arrange a helicopter evac.

This is probably a good time to point out that at least team leaders should learn helicopter etiquette, including landing site requirements, safe approach to the helicopter, and how to communicate using both radio (modified HAM VHF set) and hand signals. The pilot will probably not trust you, anyways. Do not be offended.

The victim should relax and be immobilized as much as practical. Immobilize the bitten arm or leg, splint if possible, and compress near the wound with a wide ace bandage, which may delay venom transfer.

Primary treatment for snakebike venom is anti-venom (Wyeth polyvalent antivenom); it is difficult to obtain due to dangerous allergic reactions in patients (which can be managed in a professional setting but are dangerous in the wild). Antibiotics will also typically be required to manage secondary infection.

1. Bite Treatments at University of Southern California, 75-85
2. Jenkins M, Russel FE: Physical Therapy for Snake Venom Poisoning, Phys Therapy 54:1298, 1974