Wilderness and Rescue Medicine 7th Edition Jeffrey Isaac, PA-C and David E. Johnson, MD

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Section II: Critical Body Systems

As volume shock progresses and the compen- sation mechanisms are overwhelmed, oxygen- ation and perfusion of the brain will be further reduced resulting in more profound brain failure . The patient’s level of consciousness will decrease and the brain’s ability to control the circulatory and respiratory systems will become impaired. Cardiac output will decrease as heart muscle is deprived of oxygen. Circulatory collapse and respiratory failure are imminent. This is called decompensated shock. The rate of progression of volume shock will be directly related to the rate of fluid loss, but the vital sign pattern and trend will be the same: altered mental status, increasing pulse and respi- ratory rate, and decreasing skin perfusion and urine output. In the case of severe bleeding, the patient may progress from compensated volume shock to decompensated shock within minutes. Dehydration, on the other hand, can progress over many hours or days. Either way, if volume shock cannot be reversed, the patient will die. Field Treatment of Volume Shock Stop the Fluid Loss. Severe bleeding is a criti- cal system problem identified during the primary assessment and treated as part of basic life support (see the basic and advanced life support chapter). Dehydration is a more common mechanism for volume shock in the wilderness or offshore setting. It is less urgent, but no less important, and is also initially treated by stopping the fluid loss. You will need to reduce heat stress to reduce sweating or use medication to stop diarrhea or vomiting. This may or may not be easy to accomplish in a high-risk situation. Restore Blood Volume. The first aid treat- ments of reassurance, elevating the feet, and keep- ing the patient warm do nothing to address the real problem of low blood volume. A patient in volume shock from uncontrolled blood loss needs a surgeon and a hospital, and blood. Intravenous therapy with normal saline or other crystalloid solution is only a temporary treatment that may buy time, but also can cause harm.

When blood loss can be controlled or where shock is cause by dehydration, field treatment with oral, IV, or subcutaneous fluids may be definitive. Oral rehydration can take hours or days and is not ideal but may be your best option in a high-risk situation. The return of normal vital signs, along with normal urine output, is the best indication of success. If the patient is not improv- ing within a reasonable period, evacuation must be considered. Shock that you cannot reverse in the field is a life-threatening medical emergency regardless of its cause.

General Principles

Volume Shock Treatment Stop the fluid loss:

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• Control bleeding • Reduce sweating • Treat diarrhea and vomiting

Replace fluid volume: • IV blood and electrolyte solutions • Oral electrolyte solutions or water and food • Rectal or sub-cutaneous rehydration

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Maintain calories and body core temp

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Position and Protection. Regardless of the cause of volume shock, it is important to protect the patient fromheat loss.The patient in shock will not be generating much heat through metabolic processes or muscle activity, and hypothermia will greatly reduce the chances of survival. Contact with the ground, water, or cold IV solutions and bottled oxygen will exacerbate the problem. Be sure to add heat to the patient package in all but the warmest of conditions. A patient in shock should be carried horizon- tally because an upright orientation can inhibit perfusion of the brain and can be fatal. Avoid a vertical hoist into a helicopter or onto a ship, or a technical evacuation with the litter belayed in the vertical position. Oxygen. Supplemental oxygen may be brought to the scene by rescue teams. Adding more oxygen to the air the patient is breathing increases the efficiency of a limited blood supply. In the field setting, oxygen is usually administered by nasal canula at a rate just adequate to reduce symptoms