CHAPTER. Review of the Circulatory System Cardiac Compromise Basic Life Support Automated External Defibrillation Vascular Emergencies

Transcription

1 CHAPTER 18 Review of the Circulatory System Cardiac Compromise Basic Life Support Automated External Defibrillation Vascular Emergencies A cardiovascular event is a true medical emergency for a patient. The recognition and treatment of a cardiovascular event can mean the difference between life and death. This chapter reviews the circulatory system, discusses the anatomy and physiology of the cardiovascular system, and discusses the assessment and treatment of a patient experiencing a cardiac event. The chapter also covers the link between early recognition and treatment of a cardiovascular event and patient outcome. 346

2 Cardiovascular Emergencies After completing this chapter, the EMT student will be able to do the following: 1 List the parts of the cardiovascular system and how they work. 2 Describe the emergency medical care of the patient experiencing chest pain/discomfort. 3 List the indications and contraindications for automated external defibrillation. 4 Define the role of the emergency medical technician in the emergency cardiac care system. 5 Explain the impact of age and weight on defibrillation. 6 Discuss the position of comfort for patients with various cardiac emergencies. 7 Explain the importance of airway management in the patient with cardiovascular compromise. 8 Predict the relationship between the patient experiencing cardiovascular compromise and basic life support. 9 Discuss the fundamentals of and reasons for early defibrillation. 10 Explain the importance of prehospital advanced cardiac life support (ACLS). 11 Explain the importance of urgent transport to a facility with ACLS. 12 Discuss the various types of automated external defibrillators and the difference between the fully automated and the semiautomated external defibrillator. 18 Continued 347

3 Chapter Objectives cont d 13 State the reasons for ensuring that the patient is pulseless and apneic before using the automated external defibrillator. 14 Discuss what might cause inappropriate shocks. 15 Explain when you would stop cardiopulmonary resuscitation to use the automated external defibrillator. 16 Discuss rhythm monitoring. 17 List the steps in the operation of the automated external defibrillator for one emergency medical technician and two emergency medical technicians. 18 Discuss the standard of care to use when treating a patient with constant ventricular fibrillation when ACLS is not available. 19 Discuss the standard of care to use when treating a patient with recurrent ventricular fibrillation when ACLS is not available. 20 Explain the reason for not checking a pulse between shocks with an automated external defibrillator. 21 Discuss the importance of and components for postresuscitation care. 22 Explain the role medical direction plays in the use of automated external defibrillation. 23 State the reasons for reviewing each call following the use of the automated external defibrillator. 24 Discuss the components that should be included in a case review. 25 Explain the role of medical direction and protocols in the emergency medical care of the patient with chest pain. 26 List the indications for the use of nitroglycerin. 27 State the contraindications for and side effects of the use of nitroglycerin. 28 Describe the controls on an automated external defibrillator and how they work. 29 Describe event documentation. 30 Explain why the maintenance of automated external defibrillators is important. 31 Explain the reasons for giving nitroglycerin to a patient with chest pain or discomfort. 32 Demonstrate the assessment and emergency medical care of a patient experiencing chest pain/discomfort. 33 Demonstrate the application and operation of the automated external defibrillator. 34 Demonstrate the maintenance of an automated external defibrillator. 35 Demonstrate the assessment and documentation of the patient s response to the automated external defibrillator. 36 Perform the steps in assisting the patient to use nitroglycerin for chest pain or discomfort. 37 Demonstrate the assessment and documentation of patient response to nitroglycerin. 38 Practice completing a prehospital care report for patients with cardiac emergencies. 348

4 CHAPTER 18 Cardiovascular Emergencies 349 Dinner is almost done. Jack is cleaning up the remainder of the dishes while Elizabeth wipes down the table. Jane is using the broom, sweeping around the table. The ride-along, Jack, is already off to the common area, looking again at his emergency medical technology book, hoping that the tones go off soon. They already have had two runs earlier in the shift, causing dinner to run late. But it was so exciting to see the crew in action; they seemed to work so well together. Jack s prayers are answered: The county tones begin to warble, and the house lights came on. Rescue Six Thirty-six, Seventy-three Talbert Road, cross of Main, report of respiratory distress. Jack wipes his hands and heads to the garage to start up the ambulance. They pull up to a single-story tract home in one of the older sections of town. An older woman greets them at the door, looking anxious. My husband is in the back room. I think he fainted. Please hurry! What is his name, ma am? asks Elizabeth, while walking down the narrow hallway toward the back bedroom. Jim Markham, replies the woman. In the bedroom, Elizabeth leans over to the man, who is lying on the bed. Mr. Markham, how are you doing? I am... okay, the patient replied slowly, as if he were trying to convince himself that in fact he was. Although awake, Mr. Markham looked a bit confused as to where he was. He was pale, and sweating profusely. Following instructions he received from Elizabeth earlier in the shift, Jack opened the first-in bag to retrieve the penlight, stethoscope, and blood pressure cuff. Jane is busy opening the airway kit and cracking open the oxygen tank. Question: What are some of the procedures the emergency medical services crew should do immediately to help manage this patient? More than 600,000 persons die each year from various types of cardiovascular disease. Approximately half of those deaths result from sudden cardiac death. Sudden cardiac death is often the first warning sign a patient displays of cardiac disease. Up to 50% of sudden cardiac deaths occur before the patient reaches a hospital. Cardiac events are true medical emergencies. In the prehospital setting, emergency medical care can make a significant difference in the patient s survival and outcome. This chapter discusses the assessment and treatment of cardiac emergencies and the management of cardiac arrest. REVIEW OF THE CIRCULATORY SYSTEM The circulatory system can be thought of as a transport system for the body, with various one-way streets and highways along the way. As discussed in Chapter 4, the circulatory system includes not only the heart but also an integrated arterial and venous system that serves specific functions to keep the body working. The circulatory system transports oxygen and nutrients to the body and removes carbon dioxide and other wastes from the tissues. Anatomy Heart The heart is more than a muscle. The heart is the engine of the circulatory system. The heart is composed of two sides, the right side and the left side. A wall called the septum divides the two sides. Each side of the heart has an atrium and a ventricle, separated by a one-way valve, meaning the valve only allows blood to flow in one direction. The right atrium receives oxygen-depleted blood from the veins of the body and the heart and pumps it to the right ventricle. From the right ventricle the oxygen-poor blood is pumped to the lungs to be refueled. Picking up oxygen in the lungs, the blood returns to the left atrium of the heart via the pulmonary veins. The left atrium pumps the now oxygen-rich blood to the left ventricle which then pumps the blood out to the body so that the blood can deliver oxygen and nutrients.

5 350 EMERGENCY MEDICAL TECHNICIAN The one-way valve that separates the atria and ventricles prevents the backflow of blood and enables a one-way flow of blood through the heart (Fig. 18-1). Blood Vessels In addition to the heart, the circulatory system is composed of various vessels called arteries and veins in a network that is connected to the heart. Each of these arteries and veins has a specific route and a function to provide for the body. Arteries carry blood away from the heart to the rest of the body. They carry oxygen-rich blood and deliver nutrients to the various organs of the body. With each contraction of the heart, you can feel it pumping blood through the body wherever you are able to palpate a pulse. You can feel a pulse through an artery that lies close to the surface of your skin and lies over a bony prominence. Fig shows peripheral and central pulse sites. Arteries become smaller and smaller until they connect to arterioles. Arterioles become smaller and smaller until they connect with capillaries. Capillaries are intertwined with all of the tissues in the body, allowing the exchange of oxygen for carbon dioxide. The capillaries then join with tiny vessels called venules. The venules join with veins, which become larger and larger in diameter returning to the right atrium. In the right atrium, the process begins all over again. The largest artery (in diameter) of the body is the aorta. The aorta is a major artery that originates from Superior vena cava Aorta Pulmonary artery Left pulmonary artery to left lung Right pulmonary artery to right lung Right pulmonary veins Left pulmonary veins RIGHT ATRIUM LEFT ATRIUM Myocardium RIGHT VENTRICLE LEFT VENTRICLE Inferior vena cava Aorta Interventricular septum Fig Anatomy of the heart.

6 CHAPTER 18 Cardiovascular Emergencies 351 Temporal artery Facial artery Common carotid artery Brachial artery Radial artery Femoral artery Popliteal artery (behind knee) Posterior tibial artery Dorsalis pedis artery Fig Peripheral and central pulse sites. the heart and lies in front of the spine in the thoracic and abdominal cavity. At the level of the navel, the aorta divides to form the iliac arteries. These arteries supply the lower extremities with oxygen and nutrients. The pulmonary artery originates in the right ventricle of the heart. It carries oxygen-poor blood and delivers it to the lungs to be replenished. The pulmonary artery is the only artery in the body that carries oxygen-poor blood instead of oxygen-rich blood. The carotid arteries are the major arteries in the neck. They supply the head with oxygenated blood. The carotid pulse can be felt on either side of the neck next to the trachea. The femoral artery is the major artery of the thigh and supplies the groin and lower extremities with oxygenated blood. Femoral pulses can be felt on either side of the groin area at the crease between the abdomen and thigh. The radial artery supplies the lower arm and hand with oxygenated blood. Radial pulses can be felt in the distal anterior area of the wrist (near the base of the thumb on the palm side of the wrist). The brachial artery can be felt in the upper arm and can be palpated on the inside of the arm between the elbow and the shoulder. The brachial artery most commonly is used to determine a blood pressure with a sphygmomanometer (blood pressure cuff) and a stethoscope. The sphygmomanometer is placed over the brachial artery and the blood pressure is auscultated at the distal end of the brachial artery in the antecubital fossa at the elbow. Arteries that can be palpated in the lower extremities are the posterior tibial artery and the dorsalis pedis artery. The posterior tibial artery is located on the medial side of the malleolus (near the inside of the ankle). The dorsalis pedis artery is located on the anterior surface of the foot. The primary function of the venous system (veins) is to carry blood back to the heart after the arterial system has delivered oxygen and nutrients. The pulmonary vein carries blood to the left atrium of the heart from the lungs after being replenished with oxygen. From there, the blood once again is pumped out into the body. Consequently, the pulmonary vein is the only vein in the body that carries oxygen-rich blood. The venae cavae are major veins that consist of two branches: the superior vena cava and the inferior vena cava. The superior vena cava carries oxygen-poor blood from the head and arms. The inferior vena cava carries oxygen-poor blood from the lower extremities and torso. This oxygen-poor blood in both of these major veins is transported to the right atrium of the heart. As mentioned previously, the blood then is carried to the lungs from the right atrium via the right ventricle and pulmonary artery to be reoxygenated. Blood Composition What is blood? Blood is composed of numerous components including red blood cells (erythrocytes), white blood cells (leukocytes), plasma, and platelets. Red blood cells give blood its red color. They also carry oxygen to the organs of the body and carry carbon dioxide away from the organs. White blood cells help defend the body against infections. Plasma is the fluid that moves the red and white blood cells and nutrients throughout the body. It contains a variety of proteins, hormones and infection-fighting chemicals called antibodies. Platelets are special cells that make the blood form clots and help the body to stop bleeding. Physiology The left ventricle of the heart contracts, sending the oxygen-rich blood through the arteries of the body. As this occurs, you can simultaneously feel that push

7 352 EMERGENCY MEDICAL TECHNICIAN of blood by palpating any of the major arteries that are located over a bone near the surface of the skin. This is called a pulse. To review, peripheral pulses are the following: Radial Brachial Posterior tibial Dorsalis pedis Central pulses are the following: Carotid Femoral Blood pressure is the pressure exerted against the walls of an artery when the left ventricle contracts. When one is using a sphygmomanometer, this reading is called the systolic blood pressure. This pressure is recorded as the top number of the blood pressure reading. The pressure against the arteries when the left ventricle completes its contraction and is at rest is called the diastolic blood pressure. This pressure is recorded as the bottom number of the blood pressure reading, when assessed with a sphygmomanometer. Inadequate circulation can cause a state of profound depression to the vital processes of the body called shock (hypoperfusion). A lack of blood volume or a lack of blood circulating in the body can cause shock. Shock can be recognized by specific signs and symptoms as the body reacts and attempts to compensate for its loss of perfusion. Signs and symptoms of shock include the following: Pale, cyanotic, cool, clammy skin Weak but rapid pulse Rapid and shallow breathing Restlessness, anxiety, or mental dullness Nausea and/or vomiting Low or decreased blood pressure Subnormal temperature Chapter 25 further discusses the effects shock (hypoperfusion) has on the body. CARDIAC COMPROMISE As you perform your patient assessment, look for signs and symptoms that may indicate cardiac compromise. Chest pain that the patient describes as a dull pressure, a dull ache, or a squeezing or tightness can be a symptom of myocardial (cardiac muscle) compromise. The chest discomfort also may radiate into the jaw or down the arms or into the upper back. A sudden onset of sweating, even as a primary symptom, can be a significant finding and can indicate cardiac compromise. Difficulty breathing (dyspnea), anxiety, irritability, and a feeling of impending doom also can be symptoms that the emergency medical technician (EMT) should consider to be cardiac related. Abnormal pulse rate, which also may have an irregular rhythm, and an abnormal blood pressure also are common. The patient may complain of epigastric pain or nausea and vomiting. Similar symptoms can result from angina, ischemia, or myocardial infarct. Angina is a condition that usually presents as chest discomfort upon physical exertion. It usually goes away when the patient rests or when the patient takes nitroglycerin. Ischemia results when an area of the heart muscle is not receiving enough oxygen. Myocardial infarction is the result of a blockage to one of the vessels in the heart resulting in death (infarction) of heart muscle (myocardium). Assessment Well-developed assessment skills are essential in forming a field impression to determine an appropriate treatment plan for a patient with possible cardiac compromise. The initial assessment for any patient with suspected cardiac disease is the same as it is for any other type of patient. Once your scene is secure and you have your necessary personal protective gear in place, assessment can begin. Assessment should include forming a general impression and continuing with your evaluation of airway, breathing, and circulation and determining the priority status or criticality of your patient. Apply high-flow oxygen as soon as possible to any patient showing signs and symptoms of cardiac compromise. If the patient is able to interact with you and has a known history of cardiac problems, move on to your focused assessment and physical examination after your initial assessment. Patients tend to place themselves in a position that provides the most comfort to them. Be sure to allow the patient to continue to assume his or her position of comfort as you are assessing, treating, and transporting him or her. Patients with hypotension (low blood pressure) or who complain of being light-headed or dizzy may feel best when lying down. Patients who are complaining of difficulty breathing may feel best when sitting up. Be sensitive to what feels the most comfortable to the patient. Patients with cardiac symptoms should not exert themselves. Any patient who is suspected of

8 CHAPTER 18 Cardiovascular Emergencies 353 having cardiac-related signs and symptoms should not be allowed to get up and move about and should not be allowed to walk. For the patient to remain at rest during assessment and transport is crucial to avoid increasing cardiac workload. Obtain baseline vital signs including skin assessment and mental status. Important questions to ask your patient in assessing any chest pain are the OPQRST questions: O Onset P Provocation Q Quality R Radiation S Severity T Time Box 18-1 gives further details of the OPQRST assessment for evaluating a patient with chest pain. Any prior cardiac-related history is pertinent information. Included in your SAMPLE history (Signs and symptoms, Allergies, Medications, Past medical history, Last oral intake, Events preceding), you should ask the patient about any prescribed cardiac medica- BOX 18-1 OPQRST Assessment for Chest Pain Onset: When did the symptoms first occur? What were you doing when they first started? P rovocation: Does anything make the pain worse or better? Does it hurt when inhaling or exhaling? Quality: Describe the pain. Is it sharp or dull? Is it constant, or does it subside and get worse? Radiation: Does the pain go to anywhere else besides the chest? Is there pain in the jaw, arm, or back? Severity: How bad is the pain? A tool that is useful for assessing the pain of a patient with cardiac disease is the 1-to-10 pain scale. Ask the patient to rate his or her chest pain or discomfort, with 1 being the least pain and 10 being the worst pain he or she can imagine. This initial rating makes it easier to evaluate the level of pain during your ongoing assessment of the patient. It also helps you to determine whether the interventions performed are benefiting the patient and easing his or her symptoms. T ime: How long have you had the pain? When did it start and has it come and gone? Jack s first set of measured vital signs were: Pulse Respirations Blood Pressure /64 From Elizabeth s SAMPLE history and OPQRST of the complaint, Jack suspected that Mr. Markham was experiencing a cardiac emergency. His history indicated that he had high risk: he was taking medications for high blood pressure and high cholesterol. Elizabeth held up one of the medications. Jack, should we help him with his nitroglycerin? Question: Given Jack s findings, should Mr. Markham receive nitroglycerin? Why or why not? tion. You also should ask whether he or she has been prescribed nitroglycerin. Nitroglycerin continued Nitroglycerin (generic name) most commonly is found in the form of sublingual (under the tongue) tablets or in sublingual spray (Fig. 18-3). Common trade names for nitroglycerin are Nitrostat or Nitrolingual (nitroglycerin translingual) Spray. Action Nitroglycerin dilates blood vessels, decreasing the workload of the heart, which in turn alleviates cardiac-related signs and symptoms. With dilation of the blood vessels, however, comes a risk that the patient s blood pressure may decrease. If the patient s systolic blood pressure decreases to less than 100 mm Hg, place the patient in the Trendelenburg position (supine with his or her feet elevated) and withhold further administration of nitroglycerin. If the patient has a current prescription of nitroglycerin that has been issued to him or her, ask whether the patient has taken any before your arrival. For the conscious and alert patient showing signs and symptoms of a cardiac emergency, consider administration of nitroglycerin. The EMT should examine the patient s prescription of nitroglycerin to ensure that it is prescribed for the patient, is not expired, is the correct dosage, and is to be ad-

9 354 EMERGENCY MEDICAL TECHNICIAN A Use of sildenafil (Viagra), vardenafil (Levitra), tadalafil (Cialis), or similar types of drugs for erectile dysfunction within the previous 48 hours Infants and children Patient has met maximum dosage before arrival of emergency medical services (EMS) Patient does not have his or her own prescribed medication Medical direction has not authorized administration of nitroglycerin for this patient The EMT should be knowledgeable about any drug for which he or she is responsible for administering or with which he or she can assist. B Dosage The dosage for nitroglycerin is one tablet or one metered spray under the tongue (0.3 to 0.4 mg). This dosage may be repeated in 3 to 5 minutes if there is not sufficient relief of the patient s symptoms. A maximum of three doses may be given with approval from medical direction. The EMT should reassess the patient after each dose of nitroglycerin before assisting the patient with more doses. Be especially alert for blood pressure that drops less than 100 mm Hg after giving nitroglycerin. Fig Nitroglycerin. A, Spray. B, Tablet form. ministered sublingually. The patient may take up to three consecutive doses of nitroglycerin, either by sublingual pill or spray. If the patient has not met the maximum dosage, the EMT should obtain orders (online or off-line) for authorization to assist the patient with nitroglycerin administration. Once orders are obtained from medical direction for the administration of nitroglycerin, the EMT must be sure the patient meets the following criteria: Signs and symptoms of cardiac-related chest pain Systolic blood pressure greater than 100 mm Hg Physician-prescribed nitroglycerin tablets or spray in the patient s name Specific authorization from medical direction The EMT also must be certain that none of the following contraindications are present before administering nitroglycerin: Systolic blood pressure less than 100 mm Hg Head injury Administration Once medical direction has issued orders to administer nitroglycerin and the EMT has found no contraindications, the EMT should assist the patient with administering nitroglycerin. Be sure to follow the four R s of medication administration: the right medication, the right patient, the right dose, and the right route. The patient must be alert as well. Check the expiration date of the nitroglycerin. Ask the patient to lift his or her tongue and place or have the patient place the nitroglycerin tablet or one pump of spray under his or her tongue (Skill 18-1). Instruct the patient to keep his or her mouth closed and not to swallow until the tablet completely dissolves and is absorbed. Reassess the patient s blood pressure within 2 minutes of administration of the nitroglycerin. For a patient to complain of a headache or a burning sensation under the tongue is normal. Record administration of the nitroglycerin along with accurate times of the administration and any effects it has had in relieving the patient s signs and symptoms. Reassessment Ongoing assessment of the patient with cardiac disease is important. Vital signs, pain assessment, and assessment of the effects of interventions should be recurrent.

10 SKILL 18-1 Administration of Nitroglycerin 1. Follow appropriate body substance isolation precautions and assess the patient s vital signs. Consult medical direction regarding nitroglycerin administration. 2. Instruct the patient to lift his or her tongue. Place one tablet under the tongue and ask the patient to close his or her mouth. Instruct the patient to leave the tablet under the tongue until it is completely dissolved and to not chew the tablet. 4. Take the patient s blood pressure within 2 minutes of administration. Record the patient s name, the name of the medication, the dosage of the medication (listed on bottle), the time of administration, and the name of the ordering physician providing medical direction. 5. Reassess and record all vital signs. Also assess and document any effects the medication has had on the patient. Notify medical direction of any changes in the patient s condition or for requests for additional doses. 3. If the patient uses nitroglycerin spray, spray once under the tongue. Instruct the patient to close his or her mouth quickly. 355

11 356 EMERGENCY MEDICAL TECHNICIAN Transport Do not allow the patient to move himself or herself, as exertion only serves to increase the workload of the heart. Moreover, transport the patient in a position that is most comfortable for him or her. Consider any patient with signs and symptoms of cardiac compromise as critical. If available, request a tier rendezvous with advanced life support. Consider methods of transportation that are best for the patient. For example, although a patient s situation may be urgent and critical and rapid transport may be necessary, lights and sirens may cause added fear and anxiety for the patient. Assess what is necessary and explain to the patient what will occur. If it is determined that lights and sirens are needed to help control traffic, explain this to the patient. Assure the patient that safety is the primary concern. A calm and careful transport for the patient is best, and safety is the most important consideration. BASIC LIFE SUPPORT Not all patients who experience cardiac compromise experience cardiac arrest. That possibility does exist, however, and the EMT must be prepared to manage such an event by being proficient in cardiopulmonary resuscitation (CPR). Any patient who is complaining of breathing difficulty or chest pain or discomfort should be considered a candidate for potential cardiac arrest. Therefore the EMT should be prepared and have the necessary equipment nearby in anticipation of such an event (Skill 18-2). Good basic life support skills are essential. Emergency medical technicians rarely have a situation in the field that calls for performing one-person CPR (Skill 18-3). However, some situations may require it. For example, your partner may need to prepare or retrieve equipment. Similarly, he or she may be driving en route to the hospital while you are the only other EMS provider on the scene or in the back of the ambulance. You should practice these techniques and enhance them during your EMT course. In addition, defibrillation should be integrated into your oneand two-rescuer CPR skills. The use of automated external defibrillation devices is discussed later in this chapter. As a professional emergency medical provider, learning basic life support includes using body substance isolation techniques, airway adjuncts, and oxygenation and ventilation equipment such as oral or nasal airways, bag-valve-mask, and flowrestricted oxygen-powered ventilation devices. The use of these devices is discussed in Chapters 7 and 17. The EMT must practice and become proficient at using these devices along with the integration of CPR. The EMT also must assume responsibility for keeping informed of current trends in treatment standards and the latest developments in technology. Obtaining a pertinent history by interviewing bystanders and/or family members is important. The history can aid in determining the nature of cardiac arrest and what may have led to it. Document this information. Also share this information with other health care providers to assist in determining further management of the patient s condition. When available, request advanced cardiac life support (ACLS) to tier with any patient with cardiac arrest in order to continue the chain of survival. The American Heart Association defines the chain of survival as a series of actions that include early access to EMS, early CPR, early defibrillation, and early ACLS 1 (Box 18-2). BOX 18-2 Chain of Survival Early access: Early identification of a cardiac emergency and access to emergency medical services. Training the public to recognize signs of cardiac arrest and when to contact emergency medical services. Early cardiopulmonary resuscitation: Lay public education and training in performing cardiopulmonary resuscitation until emergency medical personnel can arrive. Early cardiopulmonary resuscitation is an essential element in the patient s chance of survival. Early defibrillation: Defibrillation is the most important element in reversing ventricular fibrillation and aiding the heart to resume functioning. Public access defibrillation is becoming more widespread. Early advanced care: Access to advanced cardiac life support is needed to provide the necessary life support needed for a cardiac arrest victim.

12 SKILL 18-2 Two-Rescuer Cardiopulmonary Resuscitation 1. Establish responsiveness. 2. If patient is unresponsive, one rescuer should call for help or retrieve the AED if available, while the other opens the patient s airway with a head tilt chin lift or jaw thrust. 3. Look, listen, and feel for breathing. 4. If there are no signs of breathing, provide two rescue breaths or retrieve the AED if available. Continued 357

13 SKILL 18-2 Two-Rescuer Cardiopulmonary Resuscitation cont d 5. Check for signs of circulation, including carotid pulse, signs of normal breathing, coughing, or movement. 6. If no signs of circulation, one rescuer performs 30 chest compressions, followed by two ventilations given by the second rescuer. 7. After five cycles of 30 compressions and two ventilations, the rescuer at the head should check for signs of circulation. If no signs of circulation, resume cardiopulmonary resuscitation. Check for signs of circulation after every five cycles (about 2 minutes). Rescuers should switch between providing compressions and ventilations as they tire and as convenient. 358

14 SKILL 18-3 One-Rescuer Cardiopulmonary Resuscitation 1. If the rescuer witnesses the patient suddenly collapse, the rescuer should establish unresponsiveness, then phone 911 or get the AED if available. If the lone rescuer is called to an asphyxial cause such as a drowning, the rescuer should perform five cycles of CPR (30 compressions to two ventilations each). 2. Open the airway with a head tilt chin lift or jaw thrust. 3. Look, listen, and feel for breathing. 4. If no signs of breathing, provide two rescue breaths. 5. Check for signs of circulation including carotid pulse, signs of normal breathing, coughing, or movement. Continued 359

15 SKILL 18-3 One-Rescuer Cardiopulmonary Resuscitation cont d 6. If no signs of circulation, locate landmark for compressions on the lower portion of the sternum. 7. Place the heel of one hand in the appropriate spot and place your other hand on top. Use the force from the heels of your hands only. 8. Position yourself directly over the patient s sternum and lock your elbows to deliver 30 compressions. 9. Provide two rescue breaths. 10. After approximately five cycles of 30 compressions and two ventilations, check again for signs of circulation. If no signs, resume cardiopulmonary resuscitation, checking for signs of circulation every five cycles. If there are signs of circulation but no signs of breathing, continue rescue breathing at a rate of one breath every 5 seconds. 360

16 CHAPTER 18 Cardiovascular Emergencies 361 AUTOMATED EXTERNAL DEFIBRILLATION Cardiac arrest, sometimes referred to as sudden death, can be a sudden loss of heart function. Most sudden deaths from cardiac arrest occur when the electrical impulses in the heart become rapid and chaotic. Impulses in the heart that are rapid and chaotic do not allow the heart to pump blood out to the body as it is designed to do. This electrical activity is called ventricular fibrillation (Fig. 18-4) and sometimes can be reversed with the use of a cardiac defibrillator. Early defibrillation, a continued link in the chain of survival, includes recognizing and treating ventricular fibrillation. The automated external defibrillator (AED; Fig. 18-5) is a machine designed to evaluate and recognize a patient s cardiac rhythm and deliver a shock if the patient displays a cardiac rhythm such as ventricular fibrillation. Many EMS systems have demonstrated increased survival rates of patients with cardiac arrest when using AEDs as opposed to CPR alone. Early defibrillation programs are gaining popularity in the public and in traditional health care arenas. Automated external defibrillators are functional and simple to use. As public access defibrillation programs are gaining popularity, and access to AEDs is becoming more common, response time in the chain of survival is decreasing, and survival rates for victims of sudden cardiac arrest is increasing. Overview of the Automated External Defibrillator Health care providers have been using defibrillation for cardiac arrest for many years. With the advancement of computer technology, defibrillation has evolved into an easy-to-access, easy-to-learn, and easy-to-perform treatment. Defibrillators deliver a shock to the patient s chest. The intent is to reverse the rapid, chaotic electric activity the heart experiences during ventricular fibrillation. Ventricular fibrillation sometimes is described as the heart quivering and not producing the organized impulses necessary to cause the heart to contract in an effective manner. Defibrillation can interrupt that chaotic electrical impulse and cause the heart to start contractions in a more orderly fashion. The more orderly fashion enables the heart to pump blood out to the body as designed. Most commonly, AEDs come fully automated or semiautomated. Fully automated external defibrillators require the EMT simply to apply two electrode patches to the patient s chest, attach the electrodes to the AED, and turn on the machine. The AED then an- Fig Ventricular fibrillation. Fig Example of an automated external defibrillator.

17 362 EMERGENCY MEDICAL TECHNICIAN alyzes the cardiac rhythm and delivers shocks to the patient when appropriate. A semiautomated external defibrillator operates in much the same way. The EMT turns on the power to the AED, applies the electrodes (adhesive patches) to the patient s chest, and attaches the electrode wires to the AED. The EMT then must press a button telling the machine to analyze the cardiac rhythm. Once the cardiac rhythm is analyzed, the machine, through a computer-synthesized voice, will instruct the EMT on subsequent needed actions. If it is determined that a shock is needed, the voice on the AED will instruct the EMT to deliver a shock by pushing the shock button. The AED is designed to deliver a shock only if the patient has a shockable rhythm. The AED has a microprocessor installed that evaluates the cardiac rhythm and determines whether it is a rhythm for which a shock is indicated. Ventricular fibrillation and ventricular tachycardia are rhythms that the AED will shock. Ventricular tachycardia is a rapid cardiac rhythm in which the heart beats so rapidly that it is not producing output to the rest of the body (Fig. 18-6). When the cardiac rhythm is ventricular tachycardia, the patient may or may not have a discernable pulse. The AED will advise to shock for ventricular tachycardia once the rate exceeds 180 beats per minute. The AED cannot determine whether the patient has a pulse. It can determine only what electrical rhythm the heart has. To avoid delivering a shock to a patient who has a pulse, attach the AED only to patients who are unresponsive, breathless, and pulseless. Patients with a pulse still have electrical impulses in the heart that are functioning. Shocking a patient with a pulse can cause the heart to convert into ventricular fibrillation or into asystole. Asystole (Fig. 18-7) also is known as flatline or cardiac standstill. Asystole indicates that the heart has stopped all function, including any electrical activity. In very few instances has an AED delivered an inappropriate shock. These machines are accurate at interpreting cardiac activity and which rhythms require a shock and which rhythms do not. Often failure of the machine is due to human error. A priority at every shift check is making sure that batteries are working and that extra batteries are available. The AED should not be placed on patients who have a pulse. Moreover, it should never be operated when in a moving vehicle or while moving the patient. Stop CPR while the machine is analyzing the patient s heart rhythm and while shocks are being delivered. The person operating the device should ensure that no one is touching the patient while the AED is analyzing the cardiac Fig Ventricular tachycardia. Fig P-wave asystole.

18 CHAPTER 18 Cardiovascular Emergencies 363 rhythm or while shocks are being delivered. Stop CPR and artificial ventilations while the machine is analyzing and while it is delivering shocks to the patient. Anyone touching the patient can be shocked as well. Although CPR is part of the chain of survival for patients with cardiac arrest, early defibrillation is more effective in terminating ventricular fibrillation. Because most patients with shockable rhythms are in ventricular fibrillation, stopping CPR to defibrillate is more beneficial to the patient. Cardiopulmonary resuscitation may be resumed after the initial shocks are delivered. Advantages of the Automated External Defibrillator The AED has many advantages. Operation is simple and quick. Learning to use a defibrillator is easier than learning the techniques of CPR. However, one must memorize the appropriate sequence for using the AED. After the initial training is completed, continuing education should be in place. Moreover, regular practice sessions using an AED trainer and various cardiac arrest scenarios should be in place. Skills should be evaluated periodically. Medical direction should be involved in ensuring a system of quality assurance and evaluation of cardiac arrest events. The machine can be attached to the patient and the first shock delivered within 1 minute of arrival at the patient s side. Adhesive pads make using the AED a hands-off operation. Automated external defibrillation is safer than traditional ACLS defibrillation, which requires placing and holding paddles directly onto the patient s chest. Electrodes are large and easy to place on the patient. Some AEDs have an optional rhythm-monitoring system that can be beneficial when tiering with ACLS services. Automated External Defibrillator Operation Approaching a patient with cardiac arrest requires the same initial actions as any other call requires. Practice body substance isolation using personal protective gear. If possible, don your gear while en route to the scene. Once you arrive on scene, survey the scene and ensure safety. If additional resources have not been called for already, you should request resources such as ACLS. Perform your initial assessment of patient responsiveness, airway, breathing, and circulation. If CPR is in progress by bystanders, ask them to stop while you verify pulselessness and apnea. Once it is verified the patient is pulseless and breathless, have your partner resume CPR for 5 cycles (about 2 minutes) while you prepare the AED. Skill 18-4 outlines the steps for using an AED as described in this section. Turn on the defibrillator power. Attach the adhesive pads to the patient s chest, and ensure the electrodes are attached to the AED. If the AED is a machine that has an event voice recorder, begin your narrative. Stop CPR and ask all bystanders to clear (stand away from and do not touch) the patient. Rescuers who are managing the patient s airway also must be clear of the patient. Initiate the analysis of the cardiac rhythm by pushing the analyze button. Fig depicts a universal algorithm protocol for operation of an AED. Shock Advised If the AED advises to deliver a shock, again clear the patient by ensuring that no one is touching the patient. Once the machine charges and advises to deliver the shock, press the shock button. Allow the Apply the AED to people at least 1 year old who are unresponsive and without normal breathing, coughing, or movement. Do 5 cycles (about 2 min) of CPR. 1. POWER ON the AED first. 2. ATTACH the pads to the patient s bare chest. 3. ANALYZE Always clear before analysis and shock! SHOCK ADVISED Analyze and shock. Resume CPR for 5 cycles. Check rhythm. NO BREATHING, COUGHING, OR MOVEMENT Analyze. Repeat shock as indicated. NO SHOCK ADVISED COUGHING OR MOVEMENT PRESENT Check breathing. Rescue breathe, if breathing is inadequate. Recovery position if breathing adequate. Fig Automated external defibrillator protocol.

19 SKILL 18-4 Use of the Automated External Defibrillator 1. Place the automated external defibrillator (AED) next to the patient s left ear if possible. Turn the AED on. 2. Attach the AED pads to the patient s chest as directed on the pads. 3. Allow the AED to analyze the patient s rhythm. Do not touch the patient. 4. If the AED states that a shock is advised, ensure that everyone is clear of the patient. 5. Press the shock button. Once the shock is delivered, immediately begin 5 cycles (about 2 minutes) of CPR beginning with chest compressions. 364

20 CHAPTER 18 Cardiovascular Emergencies 365 machine to shock the patient. Immediately resume CPR for 5 cycles. Check rhythm. If the patient is not breathing, provide mechanical ventilations with supplemental oxygen and initiate transport. If after any rhythm analysis, the machine advises no shock, check the patient s pulse. If the patient has a pulse, check the patient s breathing. If the patient is breathing adequately, apply high-flow oxygen by nonrebreather mask and initiate transport. If the patient is not breathing adequately, provide mechanical ventilation with supplemental oxygen and initiate transport. Standard Operational Procedures The EMT must be familiar with the operation of the device that is used in his or her EMS system. No AED can work without properly functioning batteries. Thus the EMT should check to see that the batteries are in working order at the beginning of each shift. Extra batteries also should be carried and should be accessible at all times. Although rapid defibrillation is of utmost importance, airway and ventilation are prime concerns for the patient also. As emphasized in previous learning, the body and the brain cannot survive without oxygen. Therefore, manage airway and breathing concurrently while carrying out the AED protocol. Stay clear of patients when the AED is analyzing and delivering shocks, but provide airway support and ventilations when performing CPR. If the patient has persistent ventricular fibrillation (the machine repeatedly advises to deliver a shock) and there is no ACLS available, transport as soon as possible. Additional shocks may be delivered to the patient in persistent ventricular fibrillation en route. Automated external defibrillators cannot analyze a rhythm accurately when an emergency vehicle is in motion. Thus you first must have the driver stop the vehicle before you have the AED analyze the patient s cardiac rhythm. Defibrillation in a moving vehicle is never safe because of the potential for the rescuer to be shocked. If en route with an unconscious patient who has a pulse or a patient who has been resuscitated but is unresponsive, monitor the patient s pulse frequently (every 30 seconds). If you subsequently determine that a pulse is not present, do the following: Stop the vehicle. Start CPR if the defibrillator is not immediately available. Once the AED is attached, analyze the rhythm. Deliver one shock if indicated. Resume CPR for 5 cycles. Continue transport. Single Rescuer with Automated External Defibrillator As a professional provider, you likely will not find yourself in a position of being a lone rescuer on a call. However, in the event this should occur, follow this sequence for using the AED: Perform the initial assessment (airway, breathing, and circulation). Ensure the patient is pulseless and apneic. Turn on AED power. Attach the device to the patient. Initiate rhythm analysis. Deliver the shock if directed. Follow AED protocol. Your protocols should have criteria in place for using ACLS tiers within your EMS system. Advanced cardiac life support is not required in order to use an AED; however, ACLS is a link in the chain of survival. Advanced cardiac life support can provide ongoing additional care for the patient in cardiac arrest. Implement ACLS as soon as possible. Protocols established by medical direction should explain what ac- The automated external defibrillator generally is not used for patients under the age of 1 year old. Most children experience cardiac arrest following respiratory arrest. Automated external defibrillators designed for adults may deliver a shock that has too much energy for a child less than 55 lb. This can cause additional damage to the myocardium. Many AED manufacturers now offer child pads that deliver less energy. Use these pads for children if available. If child pads are not available, use adult pads. Consult medical direction and become familiar with your local protocols and equipment for recommendations on using the automated external defibrillator for pediatric patients.

21 366 EMERGENCY MEDICAL TECHNICIAN An occasion may arise when you are called to the scene of a cardiac arrest and family members or bystanders inform you the patient does not wish to have resuscitative measures taken. It is important that you be informed of your local laws in this type of situation and follow the appropriate protocol. You may encounter a patient who has an implanted device such as a pacemaker or an implanted defibrillator. Treatment for these patients remains the same as for any other patient exhibiting signs and symptoms of a cardiac emergency. If cardiac arrest occurs in these situations, continue with protocols for cardiopulmonary resuscitation and use of the automated external defibrillator just as you would with any other patient. The only adjustments you need to make are to be sure to place the automated external defibrillator adhesive patches a few inches away from the implanted device and to inform medical control of the patient s history. tions to carry out if you are waiting for ACLS to arrive on scene. The AED is an electrical device and should be handled appropriately. Never operate the AED in or near water or in the rain. Water can transport an electric current from the device not only to the patient but also to the rescuer and bystanders if used in or near water. If necessary, move the patient to the ambulance and remove any wet clothing he or she may be wearing. When operating the AED, be sure the patient is not touching anything metal. Metal also has the ability to transmit the electric current. The possibility of electric current being transmitted when delivering a shock to the patient is an important consideration when clearing bystanders. Postresuscitation Care If the patient remains pulseless once the AED protocol has been completed, follow local protocol regarding transport with CPR, ACLS tier activation and rendezvous, and continued use of the AED. If the patient does regain a pulse after AED protocol has been followed, ensure a patent airway and maintain basic life support. Keep the AED attached to the patient while transporting to the receiving facility. Continue with a focused assessment and ongoing assessment en route. Be sure to reassess frequently any interventions you have initiated. Documentation Documentation is an important part of ongoing medical care for the patient. Document the initial and ongoing assessments and interventions performed. Also document any response or lack of response to interventions you have performed. Documentation should include shocks that have been delivered and analysis of no shocks advised. Also document the patient s vital signs and airway, breathing, and circulatory status during the AED protocol. Some systems use a standard documentation form for patients with cardiac arrest with AED use. This may be helpful in documenting the event. Defibrillator Maintenance Defibrillators require regular maintenance. The EMT should complete a maintenance checklist every shift (Fig. 18-9). Each unit the system has should be checked. Defibrillator failure is usually due to improper maintenance, most commonly battery failure.

22 CHAPTER 18 Cardiovascular Emergencies 367 A schedule for regular replacement of batteries should be established. The American Heart Association has published information regarding guidelines and additional information for the use of automated external defibrillation. Skills Maintenance Most systems require a 90-day rotation of skills verification for operation of the AED. To be well prepared during a cardiac event, you should practice your skills frequently, incorporating various cardiac arrest scenarios. Training to use an AED as an EMT does not automatically allow you to use it legally. State laws and rules and local medical direction will determine whether your EMS system is allowed to use defibrillation during a cardiac arrest event. Every cardiac arrest call with an AED used should be reviewed by the medical director or his designee. Reviews can be written reports or, if used, voice recording or solid state or magnetic tape recordings that are stored in the AED. Reviewing AED calls helps to aid in quality improvement and assurance. The review process should involve review of operator performance and review of the EMS system as a whole. This will help to ensure that every link in the chain of survival has been established and is used. VASCULAR EMERGENCIES All chest pain is not cardiac. The great vessels share the chest cavity with the heart, and disorders of or injury to these structures can cause pain and dysfunction that may mimic cardiac problems. Aneurysms This is a weakening and dilation of the artery wall. The layers that make up the artery separate, and a hematoma or bulge develops. This bulge can impair circulation beyond the aneurysm and it can leak or rupture, creating complications in the chest cavity or shock and death. Aortic Dissection Over 85% of aortic dissections present as acute chest pain. Patients most frequently will describe abrupt severe chest pain. Often patients describe the pain as going to the back between the scapulas. Many patients describe a ripping or tearing sensation in their chest. The condition is caused by a tear that causes the layers in the aorta to separate, and blood can then enter between the layers, further separating them. This can happen spontaneously, often in patients with hypertension, or it can be brought on by trauma or possibly medical procedures like catheterizations. During assessment, vital signs may indicate extension of the developing dissection. As blood flow into the arteries branching off the aorta is compromised, the pulse in one or more extremity may be diminished or obliterated. This condition can cause further cardiac complications by involving the coronary arteries, and rupture of the dissection can cause bleeding into the pericardial space. These patients require urgent medical or surgical intervention depending on the location of the aneurysm. Field care will include IV access and infusions, at least 95% oxygen by mask, and expeditious transport to an appropriate facility. Vascular Occlusions Vascular occlusions occur particularly in patients between the ages of 50 and 70. Narrowing of the vessels due to chronic atherosclerotic disease further complicated by emboli can narrow and obstruct arteries. Sudden occlusion of a vessel will cause hypoxia to the tissues counting on the vessel for its blood sup-

23 368 EMERGENCY MEDICAL TECHNICIAN Fig Automated external defibrillator operator checklist.