CHAPTER 10 SHOCK...SHOCK OBJECTIVES Upon completion of this chapter, the OEC technician will be able...

SHOCK

OBJECTIVES

Upon completion of this chapter, the OEC technician will be able to:10-1 Define shock.10-2 Describe the three primary causes of

shock.10-3 Describe how the body compensates

for shock.10-4 Define the two stages of shock.10-5 List the four major types of shock.10-6 List the classic signs and symptoms of

shock.10-7 Describe and demonstrate the

management of shock.

KEY TERMS

Anaphylactic shock, p. 228Anticoagulants, p. 231Cardiogenic shock, p. 228Distributive shock, p. 228Fainting, p. 230Hypovolemic shock, p. 227Neurogenic shock, p. 229Obstructive shock, p. 229Perfusion, p. 224Peripheral vascular resistance, p. 226Pulmonary embolism, p. 230Sepsis, p. 228Septic shock, p. 228Shock, p. 224Stroke volume, p. 226Tachycardia, p. 226Tachypnea, p. 226

HISTORICAL TIMELINE 1964. The NSP adopts the gold cross as its official emblem.

CHAPTER 10

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CHAPTER OVERVIEWOne 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 sets into motion a series of events that, unless corrected, may cause other body systems to fail and death to ensue. Shock is initially reversible but must be recognized and treated immedi-ately to prevent progression to irreversible organ dysfunction.

Shock is one of the most serious problems that OEC technicians will encounter. It is caused by various medical and traumatic conditions. Un-fortunately, the signs and symptoms of shock may not be apparent initially because the body com-pensates, maintaining normal vital signs. The pa-tient’s overall health, age, and medications taken may make shock more difficult to recognize at first. OEC technicians must be keenly aware of the causes of shock and the body’s responses to it. Using this information, OEC technicians will be better able to recognize shock and initiate appro-priate treatment (Figure 10-1).

Figure 10-1 A patroller assisting with respirations.© Edward McNamara.

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?

ANATOMY AND PHYSIOLOGYThe cardiovascular (circulatory) system, described in detail in Chapter 6, Anatomy and Physiology, in-cludes the heart, blood vessels, and blood. When functioning properly, the heart pumps oxygenated blood through arterial vessels to the capillaries, where oxygen and carbon dioxide are exchanged at a cellular level. Deoxygenated blood travels through venous blood vessels to the heart, which pumps the blood on to the lungs. There, carbon dioxide is excreted into the atmosphere and the blood is oxygenated and returned to the heart, which begins the cycle again.

Problems affecting any part of the circulatory system can disrupt this process, resulting in de-creased blood flow, cellular hypoxia, and shock.

Outdoor Emergency Care, Sixth Edition224



Review of the anatomy and physiology of the cir-culatory system will help you understand shock. If the pump (heart), blood vessels (arteries and veins), or blood is affected, tissue will not receive oxygen and nutrients, resulting in shock.

CAUSES OF SHOCKThere are different types of shock, resulting from three basic causes. Any of these three conditions results in decreased perfusion, with insufficient oxygen or nutrients reaching vital organ tissue. When two or more of these conditions occur to-gether, shock develops rapidly.1. Pump failure. If the heart cannot pump

correctly (i.e., the heart fails), then cardiac output decreases and blood is not pumped to the body adequately to sustain life.

2. Failure of blood vessels to respond properly. In this condition, the veins and arteries expand too much, pooling blood in them. The smooth muscle in the arteries and veins does not constrict these tubes during some pathological conditions.

3. Low fluid volume. In this condition, there is not enough blood to pump through the system. Blood can be lost through internal or external bleeding, or a medical condition can decrease the amount of healthy blood. Also, body fluids can be lost due to dehydration, from causes such as diarrhea or vomiting, burns, or excessive intake of diuretics (fluid pills).

STAGES OF SHOCKShock is a progressive disorder that can be divided into two stages: compensated shock and decom-pensated shock (Table 10-1).

Compensated ShockThe human body can compensate to maintain homeostasis even during times of stress or harm. The body’s systems have built-in redundancy and flexibility that correct adverse conditions with-out incurring a total shutdown of body systems or long-term organ damage. In times of increased metabolic demand, the body activates various compensatory mechanisms that help restore ho-meostasis, but those mechanisms can function only for a while unless the problem is corrected.

Table 10-1 The Progression of Shock

Progression Signs and Symptoms

Compensated shock

• Agitation• Anxiety• Restlessness• Feeling of impending doom• Altered mental status• Weak, rapid (thready), or

absent pulse• Clammy (pale, cool, moist)

skin• Pallor, with cyanosis about

the lips• Shallow, rapid breathing• Air hunger (shortness of

breath), especially if there is a chest injury

• Nausea or vomiting• Capillary refill of longer

than 2 seconds in infants and children

• Marked thirst• Narrowing pulse pressure

Decompensated shock

• Falling blood pressure (systolic blood pressure of 90 mm Hg or lower in an adult)

• Labored or irregular breathing

• Ashen, mottled, or cyanotic skin

• Thready or absent periph-eral pulses

• Dull eyes, dilated pupils• Poor urinary output

Blood Pressure and ShockDuring the early stages of shock, the patient’s blood pressure is maintained.

KEY POINT

If the body detects a decrease in the amount of blood being circulated or a sudden decrease in the amount of oxygen reaching the cells, the brain

Chapter 10 Shock 225



to vital tissues under adverse conditions. If left un-corrected, shock would inevitably lead to death (Figure 10-2). It is important to keep in mind that the body’s ability to compensate for shock early can mask a gravely serious uncorrected condition, giv-ing you the false impression that the patient is less sick or less injured than is in fact the case.

The first signs of shock are tachycardia, tachypnea (respiratory rate greater than 20 breaths per minute), delayed capillary refill (greater than 2 seconds), cool skin, anxiety or restlessness, and a normal blood pressure. Treated early, this form of shock is correctable and generally has no long-term adverse effects. Untreated, however, shock will progress until the body is no longer able to compensate. Treatment involves correcting the condition causing shock.

Decompensated ShockIf the body’s compensatory mechanisms are un-able to restore blood perfusion to the tissues, cel-lular hypoxia will worsen, and the body’s organs and systems will fail. Heart rate will continue to rise, systolic blood pressure will now begin to fall (to below 90 mm Hg), and respirations may be-come shallow. The skin will become grossly pale

sends signals that stimulate the release of epi-nephrine, a hormone that causes tachycardia (the heart to beat faster) and the ventricles to contract more forcefully. Both changes increase the stroke volume (amount of blood pumped out of the left ventricle into the aorta during one heartbeat), which enables more blood, oxygen, and nutrients to reach the body’s tissues and organs.

In addition, the central nervous system controls smooth muscles in the blood vessels, contracting the vessels (decreasing their diameter) or dilat-ing them (increasing their diameter). Peripheral vascular resistance refers to the tightening of the smaller-diameter blood vessels in the extremities. By increasing resistance of blood flow to the ex-tremities, blood flow to the vital organs increases, a key compensation in the early phases of 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 carbon dioxide. This combination of tachycardia, increased stroke volume by the heart, increased peripheral vascular resistance, and increased ox-ygen, by faster breathing, helps to stabilize the in-ternal environment, at least temporarily.

Compensated shock, therefore, is the body’s ability to maintain blood perfusion and oxygenation

Trauma of any kind

External blood loss andpooling of blood in largeinternal vessels depress

circulation

Tissues and organsreceive inadequate

supply of blood

Blood loss causesrapid heart rate and

weak pulse

Blood vessels constrictin extremities to

conserve blood causingcold, clammy skin

Low levels of oxygen tobreathing control centers

of brain makerespirations rapid and

shallow

Nervous systemreaction results inprofuse sweating

Vasoconstriction failsand blood pressure

drops

Leaking capillaries leadto loss of vital blood

plasma causingcirculatory depression

and thirst

Unresponsiveness anddeath may result

Figure 10-2 The progression of shock.© Jones & Bartlett Learning.




Of the two, hemorrhagic shock is more common and has more far-reaching effects.

Blood loss that results in hemorrhagic shock can be caused by a variety of problems, including trauma, gastrointestinal bleeding, vascular dis-ruption, vaginal bleeding, and bleeding that is a complication of pregnancy. Bleeding disorders and certain medications (discussed later) may increase the severity of bleeding by preventing blood from clotting normally.

Blood loss can be external and obvious, or it can be internal and hidden. The American College of Surgeons divides blood loss due to hemorrhage into four classes, ranging from class I, mild blood loss (less than 15% of total blood volume, or the equivalent of donating 1.5 units of blood) to class IV, extremely life threatening (blood loss of 40% of total blood volume or greater). Due to the body’s compensating mechanisms, a decrease in blood pressure may not be noted until more than 20% to 30% of total blood volume is lost.

The body can typically compensate for blood loss. Only with significant hemorrhage do alter-ations in blood pressure occur. An early indicator of hemorrhage is a relative tachycardia, but it can be difficult to attribute increased heart rate to shock in the context of someone who may be experiencing

or cyanotic and will be cool and moist to the touch. Due to severe constriction of the blood vessels in the extremities, capillary refill will be significantly delayed and may become undetectable. The pa-tient’s level of responsiveness will decrease (less than A on the AVPU scale) due to decreased ox-ygen in the brain. Treated early, decompensated shock may be corrected, but serious complications can result.

Once the body’s compensating mechanisms fail, vital signs deteriorate very rapidly as cells be-gin to die. This sets into motion a cascading effect that cannot be reversed. As more cells die, the tis-sues of various organs die, resulting in organ system failure and eventually death. Despite even aggres-sive treatment, this form of shock is not reversible and is fatal. It is difficult for a first responder to determine when shock can no longer be reversed.

TYPES OF SHOCKAs previously noted, shock occurs when one or more of the circulatory system’s components are adversely affected by disease or injury. These problems can be either volume related (e.g., not enough blood), pump related (e.g., heart not pumping correctly), or container related (e.g., di-lated blood vessels). With these possible causes firmly in mind, OEC technicians must be famil-iar with four major types of shock: hypovolemic shock, cardiogenic shock, distributive shock, and obstructive shock. Hypovolemic shock is caused by loss of circulating blood volume or body flu-ids. Cardiogenic shock is caused by the heart not pumping correctly. Distributive shock is a result of poor vessel function, resulting in the circulating blood pooling in the blood vessels. Obstructive shock is caused by a blockage in the cardiovascular system preventing blood flow.

Hypovolemic ShockHypovolemic shock results from a critical de-crease in circulating fluid volume from bleeding or a loss of internal body fluid (Figure 10-3). This is the most common type of shock an emergency medical responder will see from a patient who has excessive bleeding. There are hemorrhagic and nonhemorrhagic causes of hypovolemic shock. Injuries involving bleeding result in hemorrhagic shock, while severe dehydration from vomiting and diarrhea may result in nonhemorrhagic shock.

Upperextremity

Chest

Abdomen

Pelvis

Thigh

Leg

Ankle/foot

Figure 10-3 Potential blood loss from injuries in various parts of the body. Each bottle equals 1 pint (473 mL).© Jones & Bartlett Learning.




or stings; consumption of shellfish, nuts, or other foods; and use of certain medications (Table 10-2). Normally, when an offending source is introduced into the body, the immune system responds by re-leasing chemicals that aid the immune response to neutralize the foreign substance. In a susceptible person, these chemicals cause generalized dilation of the blood vessels and a host of other patholog-ical problems. Without intervention, anaphylactic shock can quickly lead to respiratory arrest and death. A complete description of anaphylaxis, in-cluding causes, assessment, and treatment, is pro-vided in Chapter 14, Allergies and Anaphylaxis.

Septic ShockSeptic shock is caused by a severe systemic in-fection known as sepsis and is the most com-mon cause of distributive shock. Normally the immune system’s white blood cells are released from the capillaries and attack and destroy patho-gens such as invasive bacteria. If the pathogens or their toxins overwhelm the body and get into the

anxiety due to pain from an injury, for example. In some people, a loss of up to 30% of blood volume may be required before a decrease in blood pres-sure is observed. Another way of looking at this is that if a person manifests signs of unmistakable shock immediately after an injury, it is very likely that the person has suffered severe blood loss.

Hypovolemia due to excessive water or fluid loss (nonhemorrhagic hypovolemia, meaning no blood loss) can occur with severe burns, dehydration, ex-cessive vomiting, diarrhea, sweating, and the use of diuretic medications (“water pills”) such as furose-mide (Lasix). As water is lost from the body, com-pensatory mechanisms draw water away from the plasma and direct it to the spaces between the cells. This shift in fluid removes water from the blood-stream, thereby decreasing the circulating blood volume and lowering blood pressure. This type of shock occurs over a much longer period of time.

Cardiogenic ShockCardiogenic shock is a condition in which the heart cannot adequately pump blood, resulting in poor cardiac output. Although the heart is a robust organ, it may fail for a variety of reasons, inclu-ding valve problems, which prevent the heart from filling or emptying properly; heart attack, which results from heart muscle damage; slow or fast heart rates, which decrease cardiac output; legal and illegal medications; and trauma to the heart.

Distributive ShockDistributive shock occurs when blood vessels lose their ability to constrict appropriately. The result-ing decrease in arterial vascular resistance causes blood to pool within the capillary beds, producing a sudden drop in blood pressure and cellular hypoxia. Thus, distributive shock is a container-related problem. Under normal conditions, arterial resis-tance (the diameter of the blood vessels) is reg-ulated by certain body chemicals, the nervous system, and local nerve receptors that help to en-sure blood is delivered to where it is needed. Based on the underlying cause, distributive shock (when the blood vessels dilate, pooling blood in the ves-sels) is subdivided into three subtypes: anaphylac-tic shock, septic shock, and neurogenic shock.

Anaphylactic ShockAnaphylactic shock is caused by a severe aller-gic reaction to a substance (Figure 10-4). Com-mon causes of anaphylaxis include insect bites

Figure 10-4 This patient is suffering from an anaphylactic reaction.Courtesy of Carol B. Guerrero.

Table 10-2 Causes of Allergic Reactions

• Foods (peanuts, sesame seeds, tree nuts, soy, milk, eggs, chocolate, shellfish)

• Environmental irritants (smoke, airborne particles)

• Pollen (weeds, grasses, trees)• Molds (mildew, spores)• Animal dander (skin flakes, fur)• Medications (antibiotics, pain medications)• Chemicals (latex)• Other causes (blood transfusions, organ

transplants, radiographic dyes)




contracting during inhalation and expiration. If the integrity of the chest wall or lung is compromised (most often by trauma), air can seep into the pleural space causing a tension pneumothorax (air in the pleural space compressing the lung) (Figure 10-5). Unless the air is given a way to escape, pressure within the chest cavity will rise, causing the lung to collapse and obstruction of venous blood return-ing to the heart, thus impeding the heart’s ability to pump effectively. This obstruction can signifi-cantly reduce the amount of blood that enters and exits the heart, causing a corresponding drop in blood pressure and shock. Thus, tension pneumo-thorax is a pump-related disorder caused by ob-struction of blood flow. A complete description of tension pneumothorax, its causes, and treatment are covered in Chapter 23, Chest Trauma.

Pericardial TamponadeObstructive shock can occur if fluid accumulates within the pericardium, the sac surrounding the heart. This fluid accumulation is called pericardial tamponade (Figure 10-6). As a result, the right side of the heart, which pumps blood to the lungs, cannot expand (collapses) from the pressure of the fluid, de-creasing cardiac output and causing shock. The right side of the heart is more vulnerable to such collapse than the left side because the walls of the right side are thinner and less muscular than those on the left side. Pericardial tamponade is thus a pump-related problem. Fluid that accumulates in the pericardial space may be free blood caused by penetrating chest trauma, fluid that slowly accumulates from a medical condition, or pus resulting from a massive

bloodstream, sepsis occurs, resulting in a poten-tially life-threatening illness that involves severe fever, shaking “chills,” and shock.

Although most infections resolve quickly, a variety of factors can increase the likelihood of sepsis, including how resistant the body is to the pathogens, how virulent the pathogens are, how well the immune system is functioning, and the overall health of the individual. Underlying med-ical conditions may also affect one’s ability to fight infection. Additionally, medications can ad-versely affect the immune system. Unless sepsis is corrected, the pathogens will multiply beyond control, causing profound vasodilation, cellular hypoxia, and death.

Neurogenic ShockNeurogenic shock, sometimes called spinal shock, is caused by a marked drop in blood pressure re-sulting from disruptions of the central nervous system, most often from a spinal cord injury. When the spinal cord is damaged, normal neurologic in-put to the blood vessels is disrupted, causing the vessels to dilate.

Fortunately, this process is not generally seen immediately after a spinal cord injury, usually occurring hours or possibly days later. OEC tech-nicians should never attribute low blood pressure (hypotension) seen with a recent traumatic spinal cord injury to neurogenic shock only. The most likely cause of shock in any trauma patient presenting with signs and symptoms of shock is hemorrhagic shock due to blood loss.

Obstructive ShockObstructive shock results when a blockage pre-vents oxygenated blood from reaching vital or-gans. The cause can be either external pressure being placed on the heart or a blockage within the body’s vascular system. Thus, the problem can be pump-related (heart) or container-related (blood vessels). The most common causes of obstructive shock are tension pneumothorax, pericardial tam-ponade, and pulmonary embolism.

Tension PneumothoraxBetween the membrane on the outside of each lung and the membrane on the inside of the chest cavity is a potential space, called the pleural space. This space is filled with a very small amount of pleu-ral fluid, the lubricating properties of which al-low the lungs to move freely while expanding and

Figure 10-5 A tension pneumothorax is accumulation of air in the space between the inside of the chest cavity and the lung that causes the lung to collapse.© Tomatheart/Shutterstock.




where oxygen enters the blood. When a blood clot, called a thrombus, breaks loose at a distant loca-tion, usually a vein in the legs or pelvis, it can travel as an embolism through the right side of the heart and lodge in the pulmonary artery. The resulting blockage disrupts the flow of blood through the lungs and back to the heart and prevents gas ex-change in the lungs. Pulmonary embolism is rap-idly fatal if it occurs in a large pulmonary artery

cardiac infection. Pericardial tamponade is covered in more detail in Chapter 23, Chest Trauma.

Pulmonary EmbolismA pulmonary embolism, or thromboembolism, is a condition where a blood clot becomes stuck in and blocks a pulmonary artery (Figure 10-7). The pulmonary artery connects the heart to the lung,

FaintingFainting, or syncope, is a loss of consciousness that results from a lack of blood flow to the brain. This condition may occur suddenly, resulting from the temporary dilation of the body’s veins and pooling of blood in those vessels. Hypotension or low blood pressure of brief duration occurs. Because less blood is getting to the brain, a syncopal episode occurs. Syncope is usually caused by fear, bad news, or an upsetting stimulus such as the sight of blood. It is resolved by placing the patient, or helping the patient to lie, in a supine position with the feet raised 12 inches.

Syncope is not a type of shock. Although usually a benign condition, it can be the result of an arrhythmia or other serious medical condition. The patient should be advised to seek medical care.

KEY POINT

Figure 10-6 Pericardial tamponade.© Jones & Bartlett Learning.

Normal heart Cardiac (pericardial)tamponade

Figure 10-7 A Pulmonary embolism.© Jones & Bartlett Learning.

Embolus

Infarcted area




CASE Update

You suspect the man may be injured and secure the area by placing both your skis and his in an “X” several yards above your location. When you return, you obtain a more complete history. He tells you that his doctor recently put him on a blood thinner to prevent clots. He also tells you that he is taking a beta-blocker for high blood pressure. As you are talking with him, the man appears slightly confused and says, “I don’t feel very well.” You radio for help, oxygen, and ALS transport.What do you think the problem is? What should you do next?

and is not treated immediately. A more detailed description of pulmonary embolism is presented in Chapter 13, Respiratory Emergencies.

FACTORS AFFECTING SHOCKYoung and healthy individuals have the greatest capacity to compensate for shock, especially in its early stages, whereas very young and older or chronically ill individuals have less effective com-pensatory mechanisms and may abruptly decom-pensate after an initial period of apparent stability. Other factors can influence how the body com-pensates for shock.

Children maintain vital signs even though they are in shock for a while. They have better early compensating mechanisms than adults, with tachycardia and tachypnea present early. However, when they reach a certain point in shock, they “crash” rapidly into irreversible shock. The symp-toms of shock in children usually appear late or delayed. A reliable indicator to the onset of shock in children is sudden lethargy or fussiness. Do not rely on blood pressure, which is maintained in early shock in children. Hypovolemic shock is the most common type in children, due to blood loss or hypovolemia from vomiting and/or diarrhea.

The presence of injury or illness, for example, can affect the severity of shock and can have cu-mulative effects. Preexisting medical conditions such as diabetes, heart disease, or anemia (a reduc-tion in the number of circulating red blood cells) can hasten the effects of shock. Mind-altering sub-stances can mask or mimic the signs of shock by al-tering vital signs and also can eliminate pain from an injury. Even prescribed medications can alter the body’s response to shock. OEC technicians must be aware that certain medications can mask

the classic signs of shock by preventing the body’s compensatory mechanisms from working properly.

One group of prescribed medications that can affect the presentation of shock is the beta-blockers, which are used to treat heart disease and high blood pressure. Because beta-blockers limit the heart’s ability to beat faster, users of these medications may not be able to generate a faster heart rate when the body is in shock. If the heart rate cannot increase, then the body’s abil-ity to compensate for shock by increasing cardiac output is limited. Among the most widely used beta-blockers are atenolol (Tenormin), metoprolol (Lopressor), and propranolol (Inderal).

Another group of medications of which you should be aware are anticoagulants, which inhibit the blood’s natural ability to clot (Table 10-3). Anticoagulants can prolong bleeding, which can worsen hemorrhagic shock. Thus, even a seem-ingly minor injury can result in profound shock due to the body’s inability to stop bleeding. Any patient who is taking one or more of these medica-tions must be carefully assessed for any evidence of hemorrhaging, both external and internal. As-pirin will also prolong bleeding. You must control bleeding in all patients.

Table 10-3 Anticoagulants

• Warfarin (Coumadin)• Enoxaparin (Lovenox)• Clopidogrel (Plavix)• Dabigatran (Pradaxa)• Rivaroxaban (Xarelto)• Apixaban (Eliquis)




PATIENT ASSESSMENT FOR SHOCKAssessment of patients in shock is no different than it is for any other patients. It begins with a scene size-up, during which potential threats to rescuer safety are identified and mitigated. Try to identify the mechanism or injury or nature of ill-ness, including evidence of trauma, heart attack, external or internal bleeding, allergy, or infection.

The scene size-up is followed by a primary pa-tient assessment, looking at the ABCDs (airway, breathing, circulation, and disability). Remember, when a responsive or unresponsive patient has life-threatening bleeding, it is more appropriate to address this life threat first, following a CABD sequence (circulation, airway, breathing, and dis-ability). If there is a life threat, correct it or start CPR if needed. After the ABCDs are addressed, if the patient is in shock, call for help, request ALS if available, and transport immediately.

When obtaining the history, pay close atten-tion to known allergies, as they may have precip-itated or contributed to the patient’s condition. Determine if the patient is taking any medications that could alter the body’s compensatory response to shock. Additionally, consider the patient’s age and determine whether the patient has taken any mind-altering drugs.

If you begin to suspect impending shock during your secondary patient assessment of a patient who appears stable initially, immediately shift gears, correcting the ABCDs and arranging transport. Examine the patient carefully for any ev-idence of injury, both external and internal. Care-ful consideration of the mechanism of injury, along with your knowledge of the locations of internal organs, could lead you to suspect internal bleeding.

Table 10-4 Signs and Symptoms of Shock

• Tachycardia (fast heart rate)• Hypotension (low blood pressure), occurs later• Tachypnea (shortness of breath)• Thirst, weakness, and nausea• Pale, cool, diaphoretic skin• Restlessness or combativeness• Altered mental status (occurs later)

Beta-Blockers and ShockBeta-blockers prevent the heart from speeding up, much like a governor on a car motor prevents the engine from over- revving. During shock, the heart cannot respond to pump more blood to the tissues.

KEY POINT

Obtain vital signs and repeat them, noting each value; even subtle changes in the pulse rate, blood pressure, or respiratory rate could indicate an underlying shock state. Be ever vigilant for the “classic” signs and symptoms of shock (Table 10-4).

Although it is important to recognize the clas-sic signs and symptoms of shock, remember that shock is a developing condition that may not be ob-vious when the patient is first examined due to the compensatory mechanisms previously described. Normal age-specific vital signs can be seen in the early stages of shock. It is important to note that hypotension and altered mental status come later in shock. Frequent reassessment of the patient is essential and should include monitoring the vital signs and mental status at regular intervals.

When assessing a patient for shock, keep in mind the types of shock, the conditions with which they are associated, and whether the clinical picture you are seeing fits the situation. Pay close atten-tion to the pulse pressure (the difference between systolic and diastolic pressures) because a narrow-ing of pulse pressure is an early indicator of shock in cardiac tamponade. Hot, dry skin, especially when combined with fever and low blood pressure, may indicate septic shock. Assess the patient’s face and hands for evidence of swelling, which could in-dicate an anaphylactic reaction. Neurogenic shock typically presents with warm, dry skin as opposed to the more classic presentation.

MANAGEMENT OF SHOCKManagement of a patient in shock centers on re-turning the patient to a state of homeostasis. Given that shock is caused by inadequate tissue perfusion and oxygenation, initial treatment is fo-cused on correcting any problems causing shock.

Follow the steps in OEC Skill 10-1 for the treatment of a patient in shock.




OEC SKILL 10-1 Managing Shock

Assess scene safety and follow standard precautions.

Call for help and arrange for transport that includes ALS.

To prevent heat loss, keep the patient warm and dry. Provide rapid transport.

Perform a primary patient assessment. Control major bleeding and assess

ABCDs. Correct any problems found. If the patient has no pulse, begin CPR.

Monitor the airway and administer high-flow oxygen.

Photos 1, 3, 4, and 5, © Edward McNamara; Photo 2, © Deborah Endly.

1

3

2

4

5




the patient’s hand is warm, titrate oxygen so that the reading on the pulse oximeter remains between 94 and 99%. If oxygen is not easily available, do not delay transport of the critical patient. Control external hemorrhage (severe bleeding) using the techniques presented in Soft-Tissue Injuries and Burns is Chapter 19 Keep the patient warm and dry. Additional treatment depends on the nature of other problems that are present. If you can, correct the cause of shock. The treatments for specific causes of shock, such as anaphylaxis, heart attack, and tension pneu-mothorax, are covered in other chapters.

Other therapies, such as intravenous therapy, blood, or medications, can be administered by ad-vanced care providers and are often lifesaving.

Major bleeding and problems affecting the ABCDs identified during the primary assessment must be corrected. If the patient has no pulse, im-mediately begin CPR. Ensure that the patient’s airway is open and clear, using airway adjuncts, and suction as necessary. Support the patient’s ventilatory efforts as needed. If the patient is not breathing or if breathing is slow or shallow, assist ventilations using either a pocket mask or a bag-valve mask connected to supplemental oxygen. If the patient is unresponsive, insert a properly sized oropharyngeal airway or a nasopharyngeal airway.

For a patient who is breathing, adminis-ter high-flow oxygen at 15 liters per minute via nonrebreather mask to maximize tissue oxy-genation. If a pulse oximeter is available and

CASE Outcome

Two other patrollers arrive on scene. You inform them you believe the patient is suffering from shock due to internal injuries from the fall. The situation has been made worse because he takes a beta-blocker and an anticoagulant. Working with the other patrollers, you quickly put the man on high-flow oxygen and place him into a toboggan. You ski down with the toboggan team and help them move the patient into the first-aid hut. Soon after, a helicopter arrives and transports the patient to a local trauma center.

Several months later, you are in the ski area’s cafeteria when someone taps you on the shoulder. It’s the man and he thanks you for “saving my life” and informs you that your suspicions were confirmed. Lifting his sweater, he shows you an abdominal scar. He tells you that the impact of the crash ruptured his spleen and that had you not stopped and insisted that he be treated, he likely would have died of shock.




In Summary• Shock is caused by inadequate perfusion,

or flow of blood to the cells, causing cellular and tissue hypoxia due to reduced oxygen delivery.

• Review of the anatomy and physiology of the circulatory system will help you understand shock. If the pump (heart), blood vessels (arteries and veins), or blood is affected, tissue will not receive oxygen and nutrients, resulting in shock.

• There are different types of shock, resulting from three basic causes: pump failure, failure of blood vessels to respond properly, and low fluid volume.

• Shock is a progressive disorder that can be divided into two stages: compensated shock and decompensated shock.

• There are four major types of shock:• Hypovolemic shock results from a

critical decrease in circulating fluid volume from bleeding or a loss of internal body fluid. There are hemorrhagic and nonhemorrhagic causes of hypovolemic shock.

• Cardiogenic shock is a condition in which the heart cannot adequately pump blood, resulting in poor cardiac output.

• Distributive shock occurs when blood vessels lose their ability to constrict appropriately.

• Obstructive shock results when a blockage prevents oxygenated blood from reaching vital organs. The most common causes of obstructive shock are tension pneumothorax, pericardial tamponade, and pulmonary embolism.

• Shock is a life-threatening condition.• It is important to quickly identify the

cause of shock and correct it if possible. The longer shock goes uncorrected, the less likely the patient is to recover.

• A patient’s blood pressure may be normal during the early phase of shock.

• Elderly patients do not compensate well for shock.

• Children maintain vital signs better than adults, until they go into irreversible shock.

Key TermsAnaphylactic shock A type of distributive shock that occurs when a person reacts violently to a substance to which he or she has become sensitized.Anticoagulants Medications that prevent blood from clotting; “blood thinners.” Cardiogenic shock A type of shock caused by inadequate function of the heart, or pump failure, resulting in poor cardiac output.Distributive shock A type of shock resulting from widespread dilation of the small arterioles, venules, or both.Fainting A loss of consciousness that results from a lack of blood flow to the brain. This condition may occur suddenly, resulting from the temporary dilation of the body’s veins and pooling of blood in those vessels. May also be referred to as syncope.Hypovolemic shock A type of shock caused by an inadequate amount of fluid or volume in the circulatory system.Neurogenic shock A type of distributive shock that is caused by disruptions of the central nervous system, most often from a spinal cord injury.Obstructive shock A type of shock caused by a blockage that prevents oxygenated blood from reaching vital organs.Perfusion The circulation of blood within an organ or tissue in adequate amounts to meet the cells’ current needs for oxygen, nutrients, and waste removal.Peripheral vascular resistance The tightening of the smaller-diameter blood vessels in the extremities, enabling increased blood flow to the vital organs.

CHAPTER REVIEW

235Chapter 10 Shock



Pulmonary embolism A condition where a blood clot becomes stuck in and blocks a pulmonary artery. May also be referred to as thromboembolism.Sepsis A serious medical condition caused by the presence of pathogenic organisms or their toxins in the blood, leading to a systemic inflammatory response.Septic shock A type of distributive shock that is caused by severe systemic infection.Shock Inadequate perfusion, or flow of blood to the cells, causing cellular and tissue hypoxia due to reduced oxygen delivery.Stroke volume The amount of blood pumped out of the left ventricle into the aorta during one heartbeat.Tachycardia A heart rate greater than 100 beats per minute in adults.Tachypnea A respiratory rate greater than 20 breaths per minute in adults.

Chapter Questions1. Shock is defined as:

a. failure of the cardiovascular (circulatory) system to maintain adequate blood flow to tissues.

b. failure of the kidney to maintain adequate urine output.

c. failure of the nervous system to send signals to the tissues.

d. failure of the heart to beat correctly.

2. In order to compensate for shock, the brain sends signals to the body causing:a. blood vessels in the extremities to

dilate.b. blood vessels of the heart to constrict.c. rate and force of heart contractions to

increase.d. rate and depth of respirations to

decrease.

3. A patient who is stung by a bee goes into anaphylactic shock. Blood vessels dilate, causing blood to pool in the vessels. What type of shock is this?a. Hypovolemicb. Cardiogenic

c. Obstructived. Distributive

4. You have been treating a patient with severe head injuries. His pulse is rising, his systolic blood pressure is falling, his respirations are shallow, his skin is cyanotic, and he has an altered mental status. In which stage of shock is this patient?a. Compensatedb. Decompensatedc. Irreversibled. Neurogenic

5. A man has a laceration on his arm and is bleeding. A woman nearby tells you that she cannot stand the sight of blood and then faints. Her fainting is the result of:a. temporary dilation of the body’s veins,

resulting in the pooling of blood in those vessels.

b. the heart not adequately pumping blood, resulting in poor cardiac output.

c. a critical decrease in circulating blood volume from bleeding or a loss of internal body fluid.

d. blockage within the body’s vascular system preventing oxygenated blood from reaching vital organs.

6. Your patient has received a crushing injury to the abdomen. You do not find any external injuries. You notice that your diaphoretic patient’s skin has become pale and cool. Your patient is anxious and complains of thirst and nausea. Your emergency care should include:a. cooling the patient with damp towels

or ice packs to the neck, armpits, and groin.

b. transporting the patient in the toboggan with the head uphill.

c. arranging for rapid transport to a medical facility.

d. providing water.

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7. A patient has a possible ruptured spleen, with a fast heart rate and dropping blood pressure. This type of shock is called:a. hypovolemic.b. cardiogenic.c. obstructive.d. distributive.

8. A patient with signs of shock attributed to pump failure has:a. poor cardiac output.b. femoral arterial bleeding.c. tension pneumothorax.d. sepsis.

Design Credits: Mountain: © thianchai sitthikongsak/Getty Images; Honeycomb Texture: © Erlon Silva - TRI Digital/Getty Images.

Answers: 1. a, Objective 10-1, p. 224; 2. c, Objective 10-3, p. 226; 3. d, Objective 10-5, p. 228; 4. b, Objective 10-4, p. 226; 5. a, Objective 10-6, p. 230; 6. c, Objective 10-7, p. 232; 7. a, Objective 10-5, p. 227; 8. a, Objective 10-2, p. 225

237Chapter 10 Shock



CHAPTER 10 SHOCK...SHOCK OBJECTIVES Upon completion of this chapter, the OEC technician will be able...

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