Rattler venom is poisonous in several different ways. It is hemotoxic, breaking down blood cells, and damaging the endothelium of vessels, which causes plasma leakage, pulmonary edema, and shock. It is also directly toxic to muscles, and can cause muscle necrosis. Additionally, it can destroy platelets and fibrinogen, causing blood clotting problems
First aid used to consist of a tourniquet above the level of the wound, but this can lead to ischemia (lack of oxygen to the tissues) and is no longer recommended. Also, wounds used to be incised (cut open with a knife), however, this has been shown to not be helpful, and can lead to infection. "Sucking" out the poison also leads to infection with no real benefits.
So, what to do for a rattlesnake bite? Currently the guidelines are to immobilize the extremity, note the time of the bite, trace the red border around the wound, and get the patient to medical help.
In the Emergency Department, treatment consists of checking the patient's airway, breathing and circulation, obtaining labs, an xray to ensure that no part of the fang is left in the wound, tetanus shot, and ekg.
There is a grading system for snake bite.
Grade 0, - no bite seen, perhaps the patient thought they were bitten, but were not. Several hours of observation may still be needed.
grade 1, - bite visible, with localized redness around wound of 1-5 inches, no other signs. This patient may be observed for up to 12 hours.
grade 2,- spreading redness, with petechiae formation (small red or purple dots, caused by hemorrhage.)
grade 3,- systemic changes with nausea, vomiting, difficulty breathing, vision changes, cardiovascular problems that start slowly and progress over hours
grade 4,- similar to grade 3, but symptoms within minutes, muscle fasciculations, convulsions, cardiovascular collapse (shock), or coma.
antivenin can be given for grades 2-4, bites. This consists of reconstituting 4-6 vials of antivenin to saline for IV drip. The potential for anaphylaxis is high with antivenin, which is usually of sheep origin, so it must be given really slowly for the first 10 minutes. The rest is given over 1 hour. It can be repeated if needed, multiple times.
First Aid for snakebite is taught as part of the AHA first aid course.