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Managing Cardlac Emrgencles
IntroductionCardiovascular emergencies account for at least 30% of all medical emergencies. The impact of cardiovascular disease is felt in every hospital and every community. Whether you are drawn to critical care practice or not, you are bound to be confronted by acute cardiac events. Responding appropriately to cardiac emergencies requires a basic familiarity with cardiac anatomy and physiology, the ability to mobilize an advanced life support team, and the skills to perform cardiopulmonary resuscitation (CPR). Advanced competencies in managing cardiac emergencies include ECG interpretation, advanced airway techniques, the appropriate use of electrical therapies and the ability to deliver appropriate intravenous medications.A Practical Guide to Managing Cardiac Emergencies is a workbook and reference tool designed to help you to effectively manage acute cardiac events. Delivered with a no-nonsense candid style, each chapter builds on previous chapters while focusing on timely and appropriate actions. This guidebook, written from thirty years of clinical and classroom experience, includes many practical insights gleaned from our students and colleagues along the way.© 2004 Nursecom Educational Technologies. All rights reserved. Permissions to be requested of the author at tracyb@nursecom.com. All feedback is gratefully welcomed at the same e-mail address. 2 Managing Cardiac EmergenciesThis Book is For YouThe management of cardiac emergencies crosses many health care disciplines: nursing, medicine, and respiratory therapy for example. This book is written for health care practitioners who are new to cardiac care and for those who wish to review or polish their skills. It is intended for those who are not fully satisfied with knowing how to respond - you also want to understand why actions are performed. We hope this is you.The AuthorsTracy Paul Barill BSN, M.Ed has been a critical care practitioner and educator for the past 16 years. His clinical experience spans intensive care, coronary care, emergency nursing, flight nursing and the community-based care of those with multiple disabilities. He has coordinated over 500 ACLS courses since 1990. Tracy also teaches programs in basic and advanced ECG interpretation. He is currently developing web based learning tools for health care professionals. Many of these web learning tools can be found at www.skillstat.com.Michael N. Dare RN, BPE, EMT-P has a diverse background in both teaching and clinical practice. Michael’s clinical expertise spans most areas of critical care nursing as well as prehospital advanced life support as a paramedic. He facilitates ACLS, PALS and trauma courses on a regular basis. He has also facilitated critical care nursing certification programs. How to Use This BookThis book is designed for the busy health care professional. If you are looking for a quick start on how to manage cardiac emergencies, Chapter 4: Triage and Response is a good place to start. The framework that is the core to this chapter is also the core to this book. Otherwise, the book is written with each chapter built on the foundation provided by the preceding chapters.A general table of contents, an expanded table of contents and an index facilitates rapid location of information. Each chapter begins and ends with a chapter summary. As well, a “quick contents” appears on the first page of each chapter to facilitate a quick and focused navigation to specific topics of interest.With a focus on both understanding and application, concepts are consistently supported with practical exercises, case studies, quizzes and memory aids. Introduction 3Each chapter is independent and can stand on its own. Read the book from cover to cover or jump around concentrating on what you need. Complete the exercises and quizzes inside each chapter. By all means, make use of the suggested resources mentioned at the end of each chapter. Many of the resources are freely available on the web. The glossary is another resource for most of the terms used.Certain conventions such as the use of icons and gray text boxes have been used throughout the book to draw attention to tips, trivia, details and important points. This book was written in a style similar to the spoken word. When medical jargon was not completely necessary, we avoided it. Our intent was a useful handbook that is easy to read and straightforward. We sincerely hope that you will find this book both useful and enjoyable.Brief SynopsisThis guidebook is included as part of the course titled “Managing Cardiac Emergencies” (MCE) offered to physicians, nurses and respiratory therapists. Eight chapters make up its contents followed by appendices of the ACLS algorithms, a cardiac glossary of terms, details on what is contained on the CD-ROM and directions on how to use the CD-ROM.The ‘stop’ hand signal marks vital information often related to clinical practice. The symbol of a string tied around the index finger is used as a reminder.The icon of a magnifying glass marks supplementary explanations on various topics.A symbol of an arrow on target signifies tips, trivia, and useful short-cuts.@ Synonymous with the internet, this icon marks any supplemental resources. 4 Managing Cardiac EmergenciesChapter 1: The Heart and Cardiac Output provides an introductory discussion on the parameters that determine the heart’s effectiveness as a pump. Case studies examine such issues as cardiac ischemia, heart failure and cardiogenic shock as they relate to cardiac output.Chapter 2: Electrical Interventions outlines defibrillation, cardioversion and transcutaneous pacing (TCP). The automatic external defibrillator (AED) is also introduced. The rationale behind safe and effective delivery of electrical interventions is offered prior to presentation of step-by-step procedures. Chapter 3: Oxygenation and Airway Management explores the many modalities of basic and advanced airway control. The use of the bag-valve-mask, the oral-pharyngeal airway, endotracheal intubation, and the use of alternative airway adjuncts are addressed in this chapter.Chapter 4: Triage and Response identifies vital steps necessary in the management of any cardiac emergency. For those who feel a little shaky around cardiac emergencies, the algorithms and tips included in this chapter may likely ease your anxiety. Chapter 5: Managing the Pulseless Patient addresses the patient who is experiencing lethal dysrhythmias (ventricular fibrillation, pulseless ventricular tachycardia or asystole) or is in the midst of pulseless electrical activity (PEA). For the pulseless patient, a timely response is key. The chapter also includes tips and techniques useful to rapidly identify the various causes of PEA.Chapter 6: Managing the Unstable Patient examines the rationale and procedures necessary to respond to a patient who requires urgent treatment. This chapter deals with hemodynamic compromise and ischemia. Management strategies are established for acute coronary syndromes, symptomatic bradycardias and tachycardias, volume deficiencies, pulmonary edema and cardiogenic shock. Chapter 7: Managing the Stable Patient with Rapid Tachycardias explores several possible tachycardias and related syndromes with a focus on a systematic make-sense care strategy. This chapter provides a practical approach to the full range of potentially stable supraventricular and ventricular tachycardias. Atrial fibrillation and flutter with rapid ventricular response is explored in detail. A section on Woolf-Parkinson-White syndrome rounds out the discussion.Chapter 8: Cardiac Pharmacology presents a simple physiological schema to cardiac pharmacology. Nodal and global antiarrhythmics, vagolytics, anti-platelet agents, fibrinolytics, vasodilators, inotropes and pressure agents are neatly placed within a physiological framework with attention to the latest in medical research outcomes studies. Introduction 5Appendix A: AHA Advanced Cardiac Life Support Algorithms provides a complete set of the revised 2004 ACLS Algorithms as advanced by the American Heart Association (AHA) and the International Liaison Committee on Resuscitation (ILCOR). Detailed notes to each algorithm are also included.Appendix B: Cardiac Glossary provides quick definitions to over 200 cardiac terms.Appendix C: Supplemental Resources is a list of on-line and off-line reference resources.Appendix D: About the CD-ROM outlines the documents and tools contained on the CD-ROM. Directions are included on how to use and install the CD-ROM.The CD-ROMA Microsoft windows compatible CD-ROM is included on the inside back cover. The CD-ROM includes:•Managing Cardiac Emergencies in eBook format. The chapters, cross-references and indexes are hyperlinked, facilitating rapid access to information of interest. The tests are fully interactive with automatic scoring and ‘lively’ feedback.•An animated ECG Simulator that includes learning and game modes•The ACLS STAT tool, a dynamic tool that randomly generates multiple quizzes across several advanced care specialties (i.e. ECG interpretation, cardiac pharmacology, acute coronary syndromes).The CD-ROM launches automatically for most computers that use windows operating systems (Windows 98 or later). The learning tools are fun, fast, effective and simple to use. Even if you are a novice to the computer, this is a good CD-ROM to check out. Let’s Get Started!Our intentions for writing this book was to share simple useful strategies in the management of cardiac emergencies, to remove some of the mystery, and to ultimately be involved in good clinical decision-making. We hope that you find this book useful and easy to read. We also hope that some of our love for cardiology is reflected here.We welcome your impressions and suggestions about this guidebook. Please e-mail us mce@nursecom.com. 6 Managing Cardiac Emergencies The Heart and Cardiac OutputManaging cardiac emergencies relies heavily on an ability to recognize, understand and respond to altered cardiac output. This point cannot be emphasized enough. By understanding the factors that influence cardiac output, memory work becomes unnecessary. This chapter serves as a beginning in the process of becoming a competent cardiac care practitioner. The cardiac cycle is first covered. Terms such as atrial kick, systole and diastole are defined. Cardiac output is then defined and defended as the important concept that it is.Using case studies, the parameters that influence cardiac output are presented. Starling’s law, preload, and afterload are addressed with particular attention to their practical clinical use. This chapter focuses on the big picture. What is the heart’s main purpose? The answer may surprise you. Quick LookThe Cardiac Cycle - p. 8What is Cardiac Output (CO) - p. 10Why is CO Vital? - p. 11 CO Parameters - p. 16Applying CO Concepts - p. 22Summary - p. 26Chapter Quiz- p. 27“It’s all about managing cardiac output!”Not So Anonymous1© 2004 Nursecom Educational Technologies. All rights reserved. Permissions to be requested of the author at tracyb@nursecom.com. All feedback is gratefully welcomed at the same email address. 8 Chapter 1: The Heart and Cardiac Output The Cardiac CycleA complete cardiac cycle occurs with each audible ‘lub-dub’ that is heard with a stethoscope. During this heartbeat, both atria simultaneously contract followed soon after by the contraction of the ventricles. Systole is the contractile phase of each chamber while diastole is the relaxation phase. During the cardiac cycle, the atria and the ventricles each have periods of both systole and diastole.The purpose of the cardiac cycle is to effectively pump blood. The right heart delivers deoxygenated blood to the lungs. Here oxygen is picked up and carbon dioxide is breathed off. The left heart delivers oxygenated blood to the body. Normally, the volume of blood ejected by the right ventricle to the lungs is about the same as the volume ejected by the left ventricle. A mismatch in volumes ejected by the ventricles (i.e. right ventricle pumps more blood than the left ventricle) can result in heart failure. Figure 1.1 Route of Blood Flow Through the HeartDe-oxygenated blood enters the right side of the heart via the vena cava and is ejected through to the lungs where oxygen is replenished and carbon dioxide diffuses out to the lungs. Oxygenated blood enters the left side of the heart and is subsequently delivered to the body.The synchronized actions of the atria and the ventricles are coordinated to maximize pumping efficiency. This sequence of events is worth considering. Rhythm disturbances can greatly impair this synchrony, resulting in a less effective cardiac cycle. For simplicity, we’ll consider the events that lead to the ejection of blood from the right ventricle into the lungs beginning at the end of atrial diastole. These events mirror those of the left heart. Left HeartRight HeartVena Cava(and Atrium) The Cardiac Cycle 9The tricuspid valve closes during ventricular systole - otherwise, it remains open. At end atrial diastole and ventricular diastole, an open tricuspid valve provides a channel between the right atrium and the right ventricle. As a result, blood flows into both the right atrium and the right ventricle simultaneously. The ventricle receives up to 85% of its blood volume during this period. Prior to ventricular systole, the atrium contracts. Since the atrium is about 1/3 the size of the ventricle, an atrial contraction only contributes an additional15-35% of blood volume to the ventricle. This ‘topping up’ of the ventricle by the atrium is called atrial kick. Note that the conclusion of atrial systole coincides with the end of ventricular diastole.After ventricular end-diastole, the ventricle enters systole and contracts forcefully, . As the pressure within the ventricle increases, the tricuspid valve closes to ensure forward blood flow. Very soon after, the pulmonic valve opens as pressure within the ventricle becomes greater than pulmonary artery pressure. Blood is then ejected into the pulmonary arteries. As blood is ejected, ventricular pressure falls. When ventricular pressure is below the pulmonary artery pressure, the pulmonic valve closes to prevent back flow of blood into the right ventricle. As mentioned in chapter one, the closure of the AV valves (tricuspid and mitral valves) normally produces the S1 heart sound. The closure of the semilunar valves (pulmonic and aortic valves) produces the S2 heart sound. While ventricular systole ejects blood into either the pulmonary or systemic vascular systems, ventricular diastole is at least as important. Without a sufficient period of diastole, systole is ineffective. During diastole, the ventricles relax. But in relaxing, the ventricles open to regain their pre-contractile size, effectively dropping the chamber pressure below that of the vena cava. As a result, blood is drawn into the ventricle during ventricular (and atrial) diastole. Then the cardiac cycle begins again.And this cardiac cycle is repeated over 100,000 times daily! Remarkable. Atrial kick occurs as the atria contract prior to ventricular contraction. Atrial kick contributes 15-35% to the volume of blood in the ventricle. This extra volume in turn increases cardiac output by a similar 15-35%. Note: as we age, atrial kick tends to be a more significant contributor to cardiac output (closer to 35%). This is one reason that our older patients are more affected by rhythm disturbances such as atrial fibrillation (a quivering of the atria rather than a coordinated contraction) than our younger patients. Atrial fibrillation causes a complete loss of atrial kick. 10 Chapter 1: The Heart and Cardiac Output What is Cardiac Output? This term ‘cardiac output’ has been used a few times already. What is cardiac output? Simply, cardiac output is the amount of blood ejected by the left ventricle in one minute. The left ventricle seems to get the lion’s share of attention perhaps because the body’s blood flow and pulse are provided by the left ventricle. For an adult, an average cardiac output is about 5-8 liters of ejected blood per minute. With strenuous activity, an adult’s cardiac output can increase to an amazing 25 liters per minute to satisfy the body’s demands for oxygen and nutrients.Some of us readily remember that cardiac output is calculated via the following formula:Cardiac output is a product of heart rate (beats per minute) and stroke volume. Stroke volume is the amount of blood ejected by the left ventricle with each contraction. Let’s put this in perspective. What is your pulse rate? If a typical cardiac output is about 5000 ml (5 liters), what is your approximate stroke volume? For example, a patient named Mary has a pulse of 72/minute. 5000 = ____(SV) X 72 (HR)With a little math, Mary’s stroke volume is calculated to be about 70 ml. SV = 5000 / 72 = 70 mlTherefore, each time Mary’s left ventricle beats, it ejects about 70 ml of blood. Mary turns out to be about average when it comes to stroke volume. A typical stroke volume for adults is 50-80 ml. How about your stroke volume?Cardiac Output = Stroke Volume x Heart RateorCO = SV x HR . guidebook. Please e-mail us mce@nursecom.com. 6 Managing Cardiac Emergencies The Heart and Cardiac OutputManaging cardiac emergencies relies heavily on. ability to deliver appropriate intravenous medications.A Practical Guide to Managing Cardiac Emergencies is a workbook and reference tool designed to help