Wilderness and Rescue Medicine 8th Edition

1 79

Section V: Environmental Medicine

the rare cases of fatal neurotoxin envenomation, the cause of death is usually respiratory failure due to paralysis of the diaphragm and chest wall musculature. Tissue toxins destroy body cells, causing inflam- mation, pain, and swelling. Damage is usually localized, with distal ischemia and infection as anticipated problems. Severe envenomation can also produce systemic effects and multi-organ failure and volume shock. Many organisms use a combination of tis- sue toxin and neurotoxin to subdue their prey. Antidotes are available to the toxins of some spe- cific organisms and to some groups of similar spe- cies. It is well worth research into toxic species and the availability and location of antivenom before traveling to a new environment.

Inhaled Toxins

General Principles

6

Treatment: • BLS, PROP • Remove and dilute: PPV, fresh air and oxygen • Respiratory system injury is high risk • Evacuate with ALS assistance as needed • Contact poison control

*

E . g . : Carbon monoxide, cooking and heating gas, volcanic gases .

© 2018 WMA

Carbon monoxide gas causes no direct respira- tory system injury but impairs oxygenation by dis- placing oxygen from receptor sites on hemoglobin molecules in red blood cells. Symptoms include headache, altered mental status, and nausea as the patient quietly asphyxiates at the cellular level. The problemmay go unnoticed until it is too late. Like most inhaled toxins, the treatment is ven- tilation and fresh air. If instituted soon enough, there should be no lasting damage to critical body systems. Direct injury can be caused by the inhalation of caustic substances. Chlorine gas directly damages the respiratory system. Symptoms include inflam- mation around the nose and mouth, coughing, wheezing, burning chest pain, and respiratory dis- tress. Early recognition and treatment of respira- tory distress is the key to survival. Identifying the causative agent in these cases is not as important as emergency field treatment and evacuation. Injected Toxins Although toxins can be injected by humans using needles, in the wilderness and marine setting we are more concerned about envenomation (toxins injected via animal stings and bites). Toxins used by organisms in the process of feeding or defense come in two basic types: neurotoxins and tissue toxins . Neurotoxins interfere with the function of the nervous system, causing muscle spasm, paralysis, and altered sensation. When symptoms suggest a neurotoxin, you will need to include respira- tory distress on your anticipated problem list. In

Injected Toxins

General Principles

7

Tissue Toxins: • Damage and destroy tissue cells • Swelling, discoloration, pain • Volume shock, multi-organ failure • Coagulopathy Neuro t oxins: • Inhibits function of nerve cells • Numbness, cramping, paralysis, spasm • Respiratory failure

*

© 2018 WMA

The vast majority of stings and bites are no more significant than the minimal discomfort they cause. The few that are significant are easily identi- fied by severe pain, swelling, or the progression of neurologic symptoms. The important principle of field treatment for significant envenomation is to provide good basic life support while moving toward the appropriate definitive medical care. Identification of the specific species encountered can be valuable in planning treatment if medi- cal facilities are accessible but should not delay evacuation.