CHAPTER 10 SHOCK OBJECTIVES KEY TERMS Upon completion of this chapter, the OEC Anaphylactic shock, p. 228 technician will be able to: Anticoagulants, p. 231 10-1 Define shock. Cardiogenic shock, p. 228 10-2 Describe the three primary causes of Distributive shock, p. 228 shock. Fainting, p. 230 10-3 Describe how the body compensates Hypovolemic shock, p. 227 for shock. Neurogenic shock, p. 229 10-4 Define the two stages of shock. Obstructive shock, p. 229 10-5 List the four major types of shock. Perfusion, p. 224 10-6 List the classic signs and symptoms of Peripheral vascular resistance, p. 226 shock. Pulmonary embolism, p. 230 10-7 Describe and demonstrate the Sepsis, p. 228 management of shock. Septic shock, p. 228 Shock, p. 224 Stroke volume, p. 226 Tachycardia, p. 226 Tachypnea, p. 226 HISTORICAL TIMELINE 1964. The NSP adopts the gold cross as its official emblem. © Jones & Bartlett Learning LLC, an Ascend Learning Company. NOT FOR SALE OR DISTRIBUTION. 9781284189599_CH10_223_238.indd 223 4/14/2020 4:37:33 PM 224 Outdoor Emergency Care, Sixth Edition CHAPTER OVERVIEW One of the most serious threats to life is the condition known as shock. Shock is defined as inadequate perfusion or flow of blood to the cells, causing cellular and tissue hypoxia due to reduced oxygen delivery. Perfusion is the circu- lation of blood within an organ or tissue in ade- quate amounts to meet the cells’ current needs for oxygen, nutrients, and waste removal. The body is perfused via the cardiovascular (circulatory) system. Although the potential causes of shock are numerous, shock occurs when one or more com- ponents of the cardiovascular system fail. This Figure 10-1 A patroller assisting with respirations. sets into motion a series of events that, unless © Edward McNamara. corrected, may cause other body systems to fail and death to ensue. Shock is initially reversible but must be recognized and treated immedi- ANATOMY AND PHYSIOLOGY ately to prevent progression to irreversible organ The cardiovascular (circulatory) system, described dysfunction. in detail in Chapter 6, Anatomy and Physiology, in- Shock is one of the most serious problems cludes the heart, blood vessels, and blood. When that OEC technicians will encounter. It is caused functioning properly, the heart pumps oxygenated by various medical and traumatic conditions. Un- blood through arterial vessels to the capillaries, fortunately, the signs and symptoms of shock may where oxygen and carbon dioxide are exchanged not be apparent initially because the body com- at a cellular level. Deoxygenated blood travels pensates, maintaining normal vital signs. The pa- through venous blood vessels to the heart, which tient’s overall health, age, and medications taken pumps the blood on to the lungs. There, carbon may make shock more difficult to recognize at dioxide is excreted into the atmosphere and the first. OEC technicians must be keenly aware of blood is oxygenated and returned to the heart, the causes of shock and the body’s responses to which begins the cycle again. it. Using this information, OEC technicians will be Problems affecting any part of the circulatory better able to recognize shock and initiate appro- system can disrupt this process, resulting in de- priate treatment (Figure 10-1). creased blood flow, cellular hypoxia, and shock. CASE Presentation On a gentle slope, you find an approximately 55-year-old man holding his left side. You identify yourself and ask if you can examine him. While talking to him, you find he fell about 10 minutes ago on his left side. As you begin your assessment, the man says he’s fine and really doesn’t think any examination is necessary. Although he appears a little pale, his radial pulse seems normal, perhaps a little slow. As you gently touch his left upper abdomen and lower chest, he winces slightly. What should you do? © Jones & Bartlett Learning LLC, an Ascend Learning Company. NOT FOR SALE OR DISTRIBUTION. 9781284189599_CH10_223_238.indd 224 4/14/2020 4:37:51 PM Chapter 10 Shock 225 Review of the anatomy and physiology of the cir- culatory system will help you understand shock. Table 10-1 The Progression of Shock If the pump (heart), blood vessels (arteries and Progression Signs and Symptoms veins), or blood is affected, tissue will not receive oxygen and nutrients, resulting in shock. Compensated • Agitation shock • Anxiety • Restlessness CAUSES OF SHOCK • Feeling of impending doom There are different types of shock, resulting from • Altered mental status three basic causes. Any of these three conditions • Weak, rapid (thready), or results in decreased perfusion, with insufficient absent pulse oxygen or nutrients reaching vital organ tissue. • Clammy (pale, cool, moist) When two or more of these conditions occur to- skin gether, shock develops rapidly. • Pallor, with cyanosis about 1. Pump failure. If the heart cannot pump the lips correctly (i.e., the heart fails), then cardiac • Shallow, rapid breathing output decreases and blood is not pumped to • Air hunger (shortness of the body adequately to sustain life. breath), especially if there 2. Failure of blood vessels to respond properly. is a chest injury In this condition, the veins and arteries • Nausea or vomiting expand too much, pooling blood in them. • Capillary refill of longer The smooth muscle in the arteries and veins than 2 seconds in infants does not constrict these tubes during some and children pathological conditions. • Marked thirst 3. Low fluid volume. In this condition, there is not • Narrowing pulse pressure enough blood to pump through the system. Decompensated • Falling blood pressure Blood can be lost through internal or external shock (systolic blood pressure of bleeding, or a medical condition can decrease 90 mm Hg or lower in an the amount of healthy blood. Also, body adult) fluids can be lost due to dehydration, from • Labored or irregular causes such as diarrhea or vomiting, burns, or breathing excessive intake of diuretics (fluid pills). • Ashen, mottled, or cyanotic skin • Thready or absent periph- STAGES OF SHOCK eral pulses Shock is a progressive disorder that can be divided • Dull eyes, dilated pupils into two stages: compensated shock and decom- • Poor urinary output pensated shock (Table 10-1). Compensated Shock KEY POINT The human body can compensate to maintain homeostasis even during times of stress or harm. The body’s systems have built-in redundancy and Blood Pressure and Shock flexibility that correct adverse conditions with- During the early stages of shock, the out incurring a total shutdown of body systems patient’s blood pressure is maintained. or long-term organ damage. In times of increased metabolic demand, the body activates various compensatory mechanisms that help restore ho- If the body detects a decrease in the amount meostasis, but those mechanisms can function of blood being circulated or a sudden decrease in only for a while unless the problem is corrected. the amount of oxygen reaching the cells, the brain © Jones & Bartlett Learning LLC, an Ascend Learning Company. NOT FOR SALE OR DISTRIBUTION. 9781284189599_CH10_223_238.indd 225 4/14/2020 4:37:54 PM 226 Outdoor Emergency Care, Sixth Edition sends signals that stimulate the release of epi- to vital tissues under adverse conditions. If left un- nephrine, a hormone that causes tachycardia (the corrected, shock would inevitably lead to death heart to beat faster) and the ventricles to contract (Figure 10-2). It is important to keep in mind that more forcefully. Both changes increase the stroke the body’s ability to compensate for shock early can volume (amount of blood pumped out of the left mask a gravely serious uncorrected condition, giv- ventricle into the aorta during one heartbeat), ing you the false impression that the patient is less which enables more blood, oxygen, and nutrients sick or less injured than is in fact the case. to reach the body’s tissues and organs. The first signs of shock are tachycardia, In addition, the central nervous system controls tachypnea (respiratory rate greater than 20 breaths smooth muscles in the blood vessels, contracting per minute), delayed capillary refill (greater than the vessels (decreasing their diameter) or dilat- 2 seconds), cool skin, anxiety or restlessness, ing them (increasing their diameter). Peripheral and a normal blood pressure. Treated early, this vascular resistance refers to the tightening of the form of shock is correctable and generally has no smaller-diameter blood vessels in the extremities. long-term adverse effects. Untreated, however, By increasing resistance of blood flow to the ex- shock will progress until the body is no longer able tremities, blood flow to the vital organs increases, a to compensate. Treatment involves correcting the key compensation in the early phases of shock. condition causing shock. At the same time, the brain sends signals to increase the rate and depth of respirations to bring more oxygen into the body and expel more Decompensated Shock carbon dioxide. This combination of tachycardia, If the body’s compensatory mechanisms are un- increased stroke volume by the heart, increased able to restore blood perfusion to the tissues, cel- peripheral vascular resistance, and increased ox- lular hypoxia will worsen, and the body’s organs ygen, by faster breathing, helps to stabilize the in- and systems will fail. Heart rate will continue to ternal environment, at least temporarily. rise, systolic blood pressure will now begin to fall Compensated shock, therefore, is the body’s (to below 90 mm Hg),