Read Me Vital Signs In-Lab Guide We will be studying 5 concepts in lab 1. Study the anatomy of the Intrinsic Conduction System using heart models. 2. Study the ECG tracings, including the following: - Understand the basics of how the ECG machine works and understand what we see on the monitor by hooking up a fellow student and recording a tracing. - Understand the basic components of the Deflection waves, and identify what is happening electrically within the myocardium.. - Correlate the Deflection waves with what is happening mechanically within the heart, specifically: Take Note! i. Ventricular filling ii. Ventricular systole iii. Valve closure (i.e., when we expect to hear the heart sounds). - Analysis of the differences between a resting ECG and ECG during exercise. - Determine pulse rate at a givingg point using the ECG readout tape. - Understand what artifact is on the readout.. 3. Identify the pulse points. points. Understand why we takee the patient s pulse at these specific 4. Understandd the theory and proceduree behind the auscultation of heart sounds. Understand that murmur means. 5. Understandd the theory and proceduree behind bothh the palpatory and auscultatory methods of blood pressure. Understand what the Sounds of Korotkoff represent. Also, understand the basic trends in BP as we age and/or gain weight. In addition to these 5 concepts, the student must recognize and name all equipment used. The student will not be performing any of these tests or procedures on the Lab Practical, and their ability to take pulse or blood pressure will not be assessed. The Steps in this guide do NOT have to be done in order, but rather should be performed as machinery and equipment become available! Read Me Please notice that the last few Steps can be done outside of lab
NOTE: A very useful Study Guide! This guide takes you through the important concepts that where discussed in the lab videos. There will be some conceptual questions on the lab practical it will not be all anatomy! Study Guide Check Your Knowledge, before the Practical: 1. Know the definitions of all key terms. Use your word list as a guide. 2. From the electrocardiogram, be able to: - ID all deflection waves and intervals, using your word list as a guide. Know what the waves and intervals represent regarding the heart and the cardiac cycle. - know where systole and diastole (atrial and ventricular) are located on a normal EKG. Know that the heart sounds indicate ventricular systole. - know what an artifact is, and what might cause it. - be able to determine heart rate from an ECG. Understand resting versus exercise heart rates. 3. Understand the 2 procedures for determining blood pressure, and what they are based on (that is...what are you actually measuring?). Know what the Sounds of Korotkoff represent. Understand that rising blood pressure is a natural part of aging. 4. Know the pulse sites by name. 5. Know what normal heart sounds are, and what they represent. Know the positions used for listening to heart sounds, and why we use them. Know what murmurs are, and what they represent.
STEP 1. Record and Study the ECG #1 Practice with the readout: Here is what the readout will look like, when you are done: Note that each small dot on the graph paper = 1 box. So the dark lines are 5 boxes. You do not have to memorize how much time each small box represents but know that 5 boxes = 1 sec. Q1. On the image below, I show you the 2 stepss I used to calculate the heart rate between R-R intervals A and B on a patient s ECG tracing. (see 1 and 2 on the image) Can you do it for the other R-R Intervals? Do one or two to make sure you can do it!
#2 Measuring an ECG in lab 1) Hook someone up to the machine, and get a tracing. Theree are two ECG machines in the room. If one is free, go to it and hook up a person, following the instruction sheet found at the machine. 2) Identifying Waves and Intervals. Remember that 25 blocks (5 big blocks ) = 1 second. seconds, and 3 blocks are about 0.12 seconds. So 12.5 blocks is 0.5 You are allowed to guestimate you answer to this: Measure, approximately, one of the RR, PR, QRS andd QT intervals, and compared to the normal ranges given inn the table to the right (in seconds). 3) Effect of Lead Placement Interval RRR PR QRS QT Min 0.6 0.12 MaxM 1.2 0.20 0.10 0.42 For convenience, the connections of the ECG electrodes are usually made at the ends of the limbs: at the wrists and ankles. However, since the limbs act as conductors, they can be viewed as an extension of the patient cable lead, and so it makes no difference where the electrodes are placed along the limb length. The white (Neg) electrode on the right arm is moved from its position on the wrist to a new position somewhere above the elbow. Notice there is no change in the ECG tracing. After returning the white electrode to its original position, the subject extends the right arm outwards and holds it horizontally in mid-air away from the body. The above ECG trace appears very noisy, because the recording is also picking up the EMG activity from the muscles used in extending the arm outwards. This is ARTIFACT. 4) Heart Rate Using R-R Interval Heart rate can also be determined by using a single PQRST sequence. To determine this beat- mm or by-beat heart rate you need to measure the distance between two successive R peaks (in number of small blocks) and apply the following formula:
Determinee your beat-by-beat heart rate at 3 different points onn your resting EKG and your post-exercise EKG and record them below. HR Estimation point #1 b/m HR Estimation point #2 b/m HR Estimation point #3 b/m Q2. It is difficult to have someone exercise enough to increase their heart rate, so simply answer this question: what would happen to the peaks of the QRS complex on the readout if the patient were to exercise? Q3. The range for a normal resting heart rate is 60 to 90 bpm. Many trained athletes have resting heart rates of 45 to 60 bpm or even lower. What physiological advantage is theree in a slower resting heart rate? 5) Effect of Respiration The subject takes a deep slow breath, and then exhales slowly (inhaling for 5 seconds, and exhaling for five seconds). NOTE: You may not be able to detect a big difference, depending on several factors including health of the patient, how much they are relaxed, etc. But keep reading! In sinus arrhythmia, the heart rate varies with the phase of respiration. The heart rate typically increases during inspirationn and decreases during expiration. Therefore, as observed, the R-R interval is longer during expiration. These changes are mediated through vagal reflexes. Sinus arrhythmia is more common in young healthy athletes. Oddly, it is considered very abnormal, perhaps dangerous, if the ECG tracings are too similar across the tape, with no variation, ass this may be indicative of a recent heart attack!! Q4. Now rate? have the patient hold their breath. What happens too the ECG tracings? What happens to heart NOTE: an increased heart rate is called tachycardia!
6) The Diving Reflex We just saw that heart rate increases (tachycardia) if the patient holds their breath. But we get a different response if we apply a cold compress to their face! The diving reflex, a reflex that happens if you dive in water (or otherwise submerge your face) is a physiological mechanism that allows animals, including humans, to prolong their excursions underwater. We hypothesize this mechanism to be enacted by the combination of water touching the face, position of the body in relation to a horizontal plane (laying down), and apnea (holding one s breath). Purposefully, this is an adapted trait that has allowed for increased survival when animals suddenly dive into water. In all air-breathing animals tested thus far, this diving reflex has been physiologically significant, as it has adapted over time in structure and function. However, the degree of response is relative among species, and a human s response is less intense when compared to other mammals. This difference in the degree of response may be due to humans evolving. The diving reflex is a complex cardiovascular-respiratory response, which (in total) conserves oxygen for the heart and brain. It consists of apnea (stoppage of breathing); bradycardia (slowed heart rate of course, this lowers Cardiac Output! We will see on the ECG); peripheral vasoconstriction (reduced blood flow to the periphery); and an increase in mean arterial blood pressure (mostly due to the vasoconstriction). Want to see? Do this: a. 1st record what happens when just holding your breath b. Then breathe and repeat with the ice cold pack on your face, especially near the lip and nose. The patient should have experienced a distinct drop in heart rate is observed when they held their breath and put the cold compress against their lip. This diving reflex is most pronounced a few seconds into the dive. Q5. Do you see why we put a cold compress on a person s face to calm them down, or to a crying baby s face?
STEP 2. Understanding blood pressure measurementss 1. #1 Suggestions 1. Maintain silence as much as possible. This is necessary to hear the pressure sounds. 2. Take only one complete set of data from one subject. You will not be tested on your ability to hear the sounds, or accurately determine BP. But, make sure everyone gets a chance to take a blood pressure reading. 3. At least two minutes should be allowed between each reading since the relaxation of the arterial tonus will cause the reading to be lower each time, unless the subject is rested. 2. #2 Palpatory Method. Go to a station with a sphygmomanometer. There will be instructions on taking BP using the palpatory method. Afterwards, make sure you understand these points for the exam: 1. The cuff pressure's constriction of the artery is opposed by the blood pressure. Therefore, in order to completely constrict the artery, the cuff pressure must be greater than the highest blood pressure, the systolic pressure. 3. 2. The cuff pressure is gradually decreased. At the point where the cuff pressuree drops below the systolic pressure of the blood, blood can pass through the constricted opening of the artery and the pulse will be felt. In otherr words, the systolic pressure, the highest blood pressure, will be the point at which the cuff pressure is first overcome. 3. The pulse will continue to be felt as the pressure in the cuff falls from systolic all the way down to zero. 4. Note that although the radial pulse is palpated, the systolic blood pressure actually recorded is that in the brachial artery, where the actual cuff constriction occurs. 4.
#3 Auscultatory Method. Recall that this method of determining blood pressure is based upon the fact that blood entering a collapsed artery results in RBCs being forced through an narrowed artery, which can be heard with a stethoscope. Go to a station with a sphygmomanometer. There will be instructions on taking BP using the auscultatory method. Afterwards, make sure you understand these points for the exam: 1. Initially the cuff is inflated to a level higher than the systolic pressure. Thus the artery is completely compressed, there is no blood flow, and no sounds are heard. The cuff pressure is slowly decreased. 2. At the point where the systolic pressure exceeds the cuff pressure, the Korotkoff sounds are first heard and blood passes in turbulent flow through the partially constricted artery. Korotkoff sounds will continue to be heard as the cuff pressure is further lowered. However, when the cuff pressure reaches diastolic pressure, the sounds disappear. 3. Now at all points in time during the cardiac cycle, the blood pressure is greater than the cuff pressure, and the artery remains open. #4 Then, answer these questions in preparation for thee exam: Q6. Can the palpatory method of blood pressure determination tell you both systolic and diastolic pressure or only systolic? Why? Q7. If you used the auscultatory method described in this lab to take the blood pressure of someone with blood pressure of 120/80, would you hear any sound in the brachial artery with the pressure cuff inflated to 150 mm? Why or why not? Q8. Would you hear any sounds with the cuff inflated to 40 mm? Why or why not? Q9. Would you hear any sounds with the cuff inflated to 100 mm? Why or why not? Q10. We said in the videos that, although we are taking BP at a big artery, we are really interested in ventricular systole. Why can we study ventricular systole at an artery, so far away from the ventricle?
STEP 3. Heart Sounds, Murmurs, and Pulse #1 Pulse. For the exam, know the location of the pulse points as per the accompanying diagram. Also know anything in bold face in the following text. You will not be tested on your ability to take a pulse. But, make sure everyone gets a chance to try a couple of the spots. In order to time the pulse, you may use anything with a second s hand, including the clock on the wall in lab. 1) Radial Pulse: This is probably what we're most familiar with when visiting the doctor's office. Take two fingers, preferably the 2ndd and 3rd finger, and place them in the groove in the wrist that lies beneath the thumb. Move your fingers back and forth gently until you can feel a slight pulsation - this is the pulse of the radial artery which delivers blood to the hand. Don't press too hard, or else you'll just feel the blood flowing through your fingers! You can even use your thumb. 2) Carotid Pulse: The carotid arteries supply blood to the head and neck. You can feel the pulse of the common carotid artery by taking the same two fingers and running them alongside the outer edge of your trachea (windpipe). This pulse may be easier to find that of the radial artery. Since the carotid arteries supply a lot of the blood to the brain, it's important not to press on both of them at the same time! 3) Femoral pulse: You probably can t perform this one in lab! The femoral artery carries blood to parts of the leg. Aside from the carotid artery, it is another common site to check for a pulse in an emergency situation. Think of an imaginary line running from your hip to the groin. The approximate superficial location of the femoral artery layss 2/3 of the way in from the hip. Note: the other following sites can also be tried: Facial artery: Gently run a finger along the lower edge of the jaw bone. Just beyond the 'chin' on either side, you might be able to feel the pulse of the facial artery. Brachial artery: Flex your biceps muscle. Press your thumb or a few fingers into the groove created between the biceps and other muscles, approximately 5cm from the armpit. You should be able to feel the pulse of the brachial artery. This is the major artery supplying blood to the arms. Abdominal aorta: (not shown on image) Very thin individualss may be able to note a slight pulsation beneath the stomach when lyingg down in a relaxed position. This pulsation is caused by the abdominal aorta, the continuation of the aorta from the heart. At the level of thee umbilicus (belly button), the aorta splits into the left and right common iliac arteries which deliver blood to the legs. Popliteal artery: This artery lies behind the knee. Bend your knee slightly and feel in the soft area behind the knee.
#2 Heart Sounds. For the exam, know the location of the heart sounds as per the accompanying diagram. Know what you are listening to at each spot. Also know anything in bold face in the following text. You will not be tested on your ability to hear these sounds, or distinguish a murmur. But, you can give it t a try in lab. 1) Definitions Heart sounds are the sounds you hear as the heart valvess close. Normal heart sounds are called S1 and S2. They are the "lubb-dupp" soundss that are thought of as the heartbeat. These sounds are produced when the heart valves close. Murmurs are blowing, whooshing, or rasping sounds produced by turbulent blood flow in or near the heart. Often, they are caused by turbulent blood flow through the heart valves. However, most murmurs are not indicative of a serious condition. Many children have murmurs due to the thinness of the heart s wall. The third heart sound or S3 is a rare extra heart sound that occurs soon after the normal two "lub-dub" heart sounds (S1 and S2). S3 may be normal in people underr 40 years of age and some trained athletes but should disappear before middle age. Re-emergence of this sound late in life is abnormal and may indicate serious problems like heart failure. However, it is not considered a murmur in a young adult. STEP 4. Study the anatomy of the Intrinsic Conductionn System on a heart model.
STEP 5. Relating the ECG readout to the Mechanical Events of the Heart (can be done outside of lab) #1 Background: Q11. Label the P wave, QRS complex, T wave, PR interval, and QT interval on the following diagram: Q12. How do electrical signals on the ECG trace correlate with electrical events in the myocardium? P wave: QRS complex (2 events): T wave: Q13. What mechanical event, or part of the cardiac cycle, is occurring during these 2 intervals? PR interval: QT interval: Let s begin by doing a little review from the videos and the Pre-lab Guide : Q14. There is a small lag on the graph between the P wavee and the beginning of the QRS complex. This is called the PR segment. What is happening during this segment? Q15. Indicate where you would find ventricular systole and ventricular diastole on the image below (2 instances of each). Indicate one R-R Interval. Also indicatee where you would hear the heart sounds (S1 & S2) on the middle wave. (REMEMBER: The heart sounds surround ventricular systole!) Q16. When should the pulse occur with respect to the second heart t sound? The first heart sound? Indicate on the above diagram.