Wilderness and Rescue Medicine 8th Edition

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Section I: General Principles

skill is especially helpful in recognizing when the problem is not serious, 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 status , blood pressure, skin perfusion, and body core temperature. Minor changes occur as the healthy body adapts to the various stresses of normal life. A pattern of substantial, progressive, or persis- tent changes in vital signs indicates an evolving problem. The volume shock pattern is a good example.

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 inad- equate perfusion pressure in the circulatory sys- tem resulting in inadequate tissue oxygenation. Respiratory failure is the term for inadequate oxygenation of the blood due to a serious respira- tory system problem. A serious nervous system problem causing brain failure can inhibit nor- mal 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. 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.

General Principles

Patterns and Trends

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Blood volume Skin perfusion Urine output Pulse Respiratio n Blood pressure Level of Consciousness

General Principles

Three Critical Systems Three Major Problems

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Compensated

Decompensated

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

© 2018 WMA

Circulatory System

Shock

Mental Status and Level of Consciousness

Respiratory System

Respiratory Failure

Nervous System

Brain Failure

Mental status is the most useful vital sign in wil- derness medicine. Nervous system tissue, espe- cially the brain, is exquisitely sensitive to oxygen deprivation. Subtle changes in brain function are often your earliest indicator of a problem with oxygenation and perfusion. Patients remain con- scious and alert but may become anxious and

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

© 2018 WMA

Recognizing or anticipating the development of shock, respiratory failure, or brain failure is the key to recognizing a serious problem. This