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

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Section I: General Principles

you don’t have an emergency, which is most of the time. Patterns and Trends The nervous system regulates the function of the circulatory and respiratory systems to maintain adequate oxygenation and perfusion under a vari- ety of conditions. The system also compensates for the effects of an injury or illness by adjusting cardiac output, respiratory rate and effort, and tissue perfusion. Measuring vital signs reveals the compensation mechanisms at work. We routinely look at pulse rate, respiratory rate and effort, level of consciousness and mental sta- tus, blood pressure, skin perfusion, and body core temperature. Minor changes occur as the healthy body adapts to the various stresses of normal life.

Three Critical Systems, Three Serious Problems

The organs of the circulatory, respiratory, and ner- vous systems perform the functions most essential to life. A serious problem with any one of these systems is considered an immediate threat to life. Your first steps in patient examination are focused on evaluating the function of these three systems. Your priority in patient care is to quickly correct any serious problems with oxygenation and perfusion. The serious problem called shock is inadequate perfusion pressure in the circulatory system result- ing in inadequate tissue oxygenation. Respiratory failure is the term for inadequate oxygenation of the blood due to a serious respiratory system problem. A serious nervous system problem caus- ing brain failure can inhibit normal control and function of the other two critical systems. The Circulatory, Respiratory, and Nervous sys- tems are interdependent. A problem with one quickly affects the functions of the other two.

General Principles

Patterns and Trends

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Blood volume Skin perfusion

Urine output

Pulse

General Principles

Respiration

Three Critical Systems Three Major Problems

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Blood pressure

Level of Consciousness

Compensated

Decompensated

Circulatory System

Shock

“ Accurate assessment of critical system function involves the recognition of patterns and trends.”

Respiratory System

Respiratory Failure

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A pattern of substantial, progressive, or persis- tent changes in vital signs indicates an evolving problem. The volume shock pattern is a good example. Mental Status and Level of Consciousness Mental status is the most useful vital sign in emer- gency medicine. Nervous system tissue, especially the brain, is exquisitely sensitive to oxygen depri- vation. Subtle changes in brain function are often your earliest indicator of a problem with oxygen- ation and perfusion. Patients remain conscious and alert but may become anxious and confused early in the pattern of shock or respiratory failure.

Nervous System

Brain Failure

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“Recognizing…a major problem with a critical body system is the key to recognizing a life-threatening emergency.”

©2018WMA

For example, shock from blood loss stimulates an increase in the respiratory rate and causes changes in brain function. Because the critical systems affect each other in a variety of ways, it can be a challenge to determine in which critical system the original problem lies. Recognizing or anticipating the development of shock, respiratory failure, or brain failure is the key to recognizing a life-threatening emergency. This skill is especially helpful in recognizing when