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Cardiac Emergencies |
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Introduction Nearly 50,000 deaths occur each year from cardiac disease, and the majority of them occur very suddenly. It is estimated that 600,000 Canadians have significant coronary heart disease, and many of those are at risk for sudden death or myocardial infarction . It is estimated that one-third of EMS calls will be related to cardiovascular disease. A detailed history and physical, which takes very little time (5 - 10 minutes), can provide valuable information to correct management and treatment of the cardiac patient. The first 30 - 60 minutes of the patient's cardiac signs and symptoms can be devastating. As each minute is passing, the patient could be losing function of the cardiac muscle (the heart).
Anatomy and Physiology of the Cardiac System
The Heart The heart is composed of special muscles and has four chambers. The upper chambers are called the atria and the lower chambers are called the ventricles. The heart has a pumping action that divides the heart into the right and left sides. The right side of the heart receives oxygen-poor blood and pumps the blood into the lungs to acquire oxygen. The left side of the heart receives oxygen-rich blood from the lungs and sends it to the body.
Blood enters the right side of the heart by way of the inferior and superior vena cavae. The blood passes through the right atrium into the right ventricle by means of the tricuspid valve. From there, the blood passes through the pulmonary valve and travels to the lungs by way of the pulmonary arteries. It is in the lungs that the blood picks up oxygen in exchange for carbon dioxide, and then travels back to the heart by the pulmonary veins. The oxygen-rich blood travels through the left atrium into the left ventricle by passing through the mitral valve. The blood then passes through the aortic valve and enters the systemic circulation. The oxygenated blood travels to the coronary arteries and the peripheral circulation. Arterioles carry blood from the artery to the capillary bed where cellular oxygen exchange occurs. Venules, the smallest veins, connect the capillary bed to the vein. Veins then carry the blood back to the heart.
Cardiac Conduction System The heart is composed of specialized contractile and conductive tissue responsible for the conduction system of the heart. This conduction system allows electrical impulses to be carried through the atrium and ventricle and causes the heart to beat. The electrical impulses are what form the waves on an electrocardiogram (ECG). The leads on the ECG detect the electrical transmissions of the heart and put it on paper.
Blood Supply Arteries, arterioles, capillaries, veins, and venules supply blood to the heart and body. The aorta is the major artery of the body. The aorta originates from the heart. The pulmonary artery originates from the right ventricle. The coronary arteries supply blood to the heart muscle (myocardium). The carotid arteries are the major arteries in the neck and supply blood to the brain. The brachial and radial arteries are the major arteries in the upper extremity. The femoral, post tibial, and dorsalis pedis are the major arteries in the lower extremity. All of the arteries are pulse sites on the body. Arterioles carry blood from the artery to the capillary (where the exchange of oxygen occurs). Venules connect the capillary bed to the vein. The veins carry blood back to the heart. The major veins are the pulmonary vein and the inferior and superior vena cava.
Blood Composition Blood is composed of red blood cells, white blood cells, plasma, and platelets. The red blood cells give blood its color, carry oxygen to organs, and carry carbon dioxide away from organs. The white blood cells are part of the body's defense system. The plasma is the fluid that carries the blood cells and nutrients. Platelets are essential for the clotting of the blood.
Cardiac Emergencies
Signs and Symptoms Before you can do anything about a problem, you must know what signs and symptoms to expect from the patient.
The first symptom that comes to mind is that of chest pain. Chest pain can be expressed and demonstrated in many different ways. Some will describe the pain as a squeezing in their chest. Others may describe it as dull, achy pain or "pressure-like" pain. The pain may radiate up into the neck as well as into the jaw and left arm. The pain may radiate across the chest, as well as into one or both shoulders and arms. The patient's chest pain is usually not relieved by positioning.
A good mnemonic to use to help you evaluate a patient's pain is OPQRRRST.
O - onset of symptoms P - provocation Q - quality of the pain (crushing, stabbing, dull, etc.) R - region R - radiation R -relief S - severity of the pain (usually on a scale of 1 - 10) T - time the pain or event started
Other signs and symptoms:
The Five P's of Cardiac Problems: Pain, Pale, Puffing, Pooped, Puking.
Patient Assessment You should begin the patient assessment as soon as possible.
The first step in the patient assessment is the scene size-up. This is the portion of the patient assessment thatassures scene safety and where we ascertain if additional help is required.
The initial phase is next in the patient assessment. This is the part of the assessment where a "general impression" is formed, appropriate interventions are performed, and a priority decision is made. The Responder should ensure that the patient has a patent airway and is in a position of comfort. Observe the patient for signs and symptoms of shock. Place the patient on high-flow oxygen. The initial assessment includes determining the level of consciousness and the ABC's.
The focused assessment emphasizes the nature of the illness, in this case, chest pain. Obtain SAMPLE (Signs and symptoms, Allergies, Medications, Past medical history, Last oral intake, Events leading up to the incident) history at this time. Obtain the first set of vital signs on the patient. Proceed through the patient assessment to the detailed assessment. This is the portion of the patient assessment which looks at the patient systematically and evaluates each area of the body.
The final portion of the patient assessment is the on-going assessment. The on-going assessment repeats the initial assessment, vital signs, and the focused assessment. If the patient is stable, repeat the on-going assessment every 15 minutes. If the patient is unstable repeat the on-going assessment every 5 minutes.
Nitroglycerin Administration The most common medication the cardiac patient is on is nitroglycerin. If the patient has nitroglycerin ordered it may be given to the patient during the patient assessment. Nitroglycerin is a potent vasodilator that is given for chest pain. Nitroglycerin reduces the workload of the heart.
Nitroglycerin works in seconds to relax the muscles of the blood vessel walls. This is why it is so important to give it to the patient with chest pain as soon as possible. Nitroglycerin can be administered as a sublingual spray or tablet. Because nitroglycerin lowers the blood pressure, it must not be given to a patient whose systolic blood pressure is 100 or lower. Verify the prescription belongs to the patient you are caring for and is having chest pain. Make sure the nitroglycerin has not expired and is in the appropriate bottle. Question the patient to ascertain if he has taken any previous nitroglycerin, or Viagra. Be specific in asking the question as to how much the patient has taken and at what time.
The dosage of nitroglycerin is one tablet or one spray under the tongue.
The dose may be repeated in 3 to 5 minutes if the patient experiences no relief and the systolic blood pressure remains above 100 mm Hg .
The total dosage should not exceed three tablets or three sprays, including the ones the patient may have taken prior to your arrival.
Possible side effects of nitroglycerin are:
The reassessment of the patient after administering nitroglycerin should include:
Document the medication given along with any other pertinent information.
Specific Diseases Specific diseases seen with cardiac signs and symptoms include:
The most common illness or disease seen with these signs and symptoms is that of angina pectoris. Angina is due to an inadequate blood flow to the myocardium. When the heart becomes ischemic, chest pain occurs.
Myocardial infarction is due to the blood supply being completely stopped and causes a blockage in one of the coronary arteries. Myocardial infarction can lead to cardiac arrest.
Another condition is congestive heart failure. Congestive heart failure, commonly known as CHF, occurs when the heart is unable to maintain sufficient pumping action, causing fluid to back up into the venous system.
The last disease that is of concern regarding the cardiovascular system is cardiogenic shock. Cardiogenic shock is a disease of hypoperfusion caused by inadequate pumping action by the heart.
Each of these diseases have similar signs and symptoms. All require the basic ABC's. Each of the disease entities has the potential for cardiac or respiratory arrest and must be treated as rapidly as possible and each requires a thorough patient assessment.
Automated External Defibrillator Survival of cardiac arrest depends on a series of events and critical interventions. If any critical intervention is weak or omitted the chances of survival are decreased.
The "Chain of Survival" The American Heart Association has adopted the phrase "chain of survival" as a way of remembering what to do and the importance of each step.
The "chain" consists of:
According to the American Heart Association, the third link in the "chain", early defibrillation, is the link most likely to improve survival rates. Early defibrillation includes the recognition and the treatment of the lethal dysrhythmias such as ventricular fibrillation and ventricular tachycardia. Defibrillation is the primary intervention that can make the greatest difference in survival in cardiac arrest.
Defibrillators The automated (some refer to automatic) external defibrillator is available in two types: fully automated (AED) and semi-automated (SAED).
The fully automated defibrillator operates without action by the responder except to turn on the power.
The semi-automated defibrillator "talks" the responder through the procedure by means of a computer generated voice synthesizer. The machine's purpose is to analyze the patient's rhythm and deliver shocks if required.
The AED or SAED recognizes only ventricular fibrillation and ventricular tachycardia - shockable rhythms. If the patient is in asystole (absence of a heartbeat) the machine will not recognize that particular rhythm.
The AED or SAED will shock the patient once if a shockable rhythm is detected. The shock is at 200 joules; After each shock, the AED or SAED will re-analyze the rhythm.
No one should touch the patient during the delivery of the shocks. The machine will tell the operator when to stop compressions in order for it to analyze the patient. CPR may be stopped for up to 90 seconds in order for the machine to analyze and shock the patient.
It is very important that responders are familiar with their respective department's AED or SAED. Many of the problems encountered with the AED or SAED is that of human error or mechanical failure. By knowing your equipment this can be prevented. Safety is of the utmost importance. Follow your department standard operating procedures. Know when the use of the AED or SAED is indicated or appropriate.
Certain general guidelines should be followed when using the AED or SAED.
If no advanced life support is on the scene or available continue use of the machine until:
It is not safe to defibrillate the patient on the AED or SAED in a moving ambulance - the machine can detect the movement as a shockable rhythm! If it becomes necessary to check the patient for a shockable rhythm, stop the ambulance and analyze the patient at that time.
Other safety considerations in operating the AED or SAED are:
Again, know your department's protocols!
It is important to coordinate use of the AED or SAED with the advanced life support (ALS) personnel. Your department protocols will establish guidelines for the machinery use when ALS personnel arrive at the scene. ALS should be notified as soon as possible when defibrillating. Post resuscitation components of AED or SAED use include airway and breathing monitoring, the administration of oxygen and monitoring the circulation and perfusion status of the patient.
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