Bài giảng Clinical procedures - Chapter 21: Electrocardiography and Pulmonary Function Testing

21Electrocardiography and Pulmonary Function Testing21-*Learning Outcomes21.1 Describe the anatomy and physiology of the heart.21.2 Explain the conduction system of the heart.21.3 Describe the basic patterns of an electrocardiogram (ECG).21.4 Identify the components of an electrocardiograph and what each does.21-*Learning Outcomes (cont.)21.5 Explain how to position the limb and precordial electrodes correctly.21.6 Describe in detail how to obtain an ECG.21.7 Identify the various types of artifacts and potential equipment problems and how to correct them.21-*Learning Outcomes (cont.)21.8 Identify how the ECG is interpreted.21.9 Identify common arrhythmias.21.10 Summarize exercise electrocardiography.21.11 Explain the procedure of Holter  monitoring.21.12 Describe forced vital capacity. 21-*Learning Outcomes (cont.)21.13 Describe the procedure of performing spirometry.21.14 Describe the procedure for obtaining a performing peak expiratory flow rate.21.15 Describe the procedure for performing pulse oximetry testing.21-*IntroductionPatients often have cardiovascular or respiratory problemsMedical assistantPerform screening and/or diagnostic testingUnderstand the anatomy and physiology of the heart and respiratory system21-*The Medical Assistant’s RoleElectrocardiography Graphic recording of the electrical impulses of the heartUsesEvaluate symptoms of heart diseaseCheck effectiveness or side effects of medicationsGeneral examination21-*The Medical Assistant’s Role (cont.)Pulmonary function tests Measure and evaluate a patient’s lung capacity and volumeUsesHelp detect and diagnose pulmonary problemsMonitor respiratory disordersEvaluate effectiveness of treatments21-*Anatomy of the HeartMuscular double pumpRight – receives blood from the body, sends it to the lungsLeft – receives blood from the lungs, sends it out to all parts of the bodyFour chambersTwo atriaTwo ventriclesValvesSeptum21-*Physiology of the HeartSystole – contraction phaseDiastole – relaxation phase Cardiac cycle – sequence of contraction and relaxation Cardiac muscle fibers are interconnected so when one is stimulated to contract, all fibers in the group contract.21-*Conduction System of the HeartCardiac cycle Controlled by specialized tissues in the heart wall that transmit electrical impulses Impulses cause muscle to contract and relax21-*Bundle BranchesBundle of HisSA NodePurkinje FibersAV NodePacemaker of the heartSets rhythm of contractionsBottom of right atriumImpulse delayed slightlyLocated in septum between ventriclesRelay impulse to Purkinje fibersLocated in ventricle wallsContraction of ventriclesConduction System of the Heart (cont.)21-*Conduction System of the Heart (cont.)ElectrocardiographyTransmission, magnitude, and duration of electrical impulses of the heartPolarityHaving a positive and negative poleResting cellPositive outsideNegative insideDepolarization Impulse that initiates a contractionRepolarization Period of electrical recovery following depolarizationPrior to polarized (resting) state21-*Conduction System of the Heart (cont.)Basic pattern of the ECGWaves (deflections) are labeled P, Q, R, S, T, U21-*Apply Your KnowledgeTrue or False___ The AV node is the heart’s pacemaker.___ The medical assistant does not perform ECGs or PFTs.___ The bundle branches relay impulses to the Purkinje fibers in the ventricles.___ The heart is resting in the polarized state.___ Depolarization initiates contractions of atria and ventricles.___ Repolarization occurs before depolarization. FANSWER:TTTFFfollowingmaySA21-*The ElectrocardiographElectrical impulses are detected through the skinMeasuresAmplifies – signal is increasedRecords using the stylus 21-*The Electrocardiograph (cont.)Types of electrocardiographsStandard machine – 12-lead, which records 12 different views at onceSingle channel – one lead and records only one view21-*The Electrocardiograph (cont.)Electrodes and electrolyte productsElectrolyte – enhances transmissions of electric currentElectrodesTen areas of the bodyRight and left armsRight and left legsSix locations on the chestEnables physician to pinpoint origin of problems21-*The Electrocardiograph (cont.)LeadsProvide different images of electrical activityMarked automatically on the ECG Limb leads Three standard – I, II, IIIThree augmented – AVF, AVR, AVLPrecordial leads – V1 through V621-*The Electrocardiograph (cont.)ECG paperSingle or multichannel availableHeat- and pressure-sensitiveStandardized to permit uniform interpretationVertical axis – strength of impulse (millivolt)Horizontal axis – time 0.04 sec5 mm(0.5 mV)1 mm(0.1 mV)1 mm5 mm0.2 sec21-*The Electrocardiograph (cont.)ControlsStandardization controlSpeed selector – 25mm/sec standardSensitivity control – adjusts height of tracing Lead selector – enables selection of a single leadCentering control – adjusts position of stylusLine control – adjusts darkness of lineOn/Off switch21-*Apply Your KnowledgeMatching:___ Adjusts position of stylus A. Vertical axis___ Adjusts height of tracing B. Sensitivity control___ Adjusts darkness of tracing C. Precordial leads___ Measures strength of impulse D. Horizontal axis___ Measures time E. Limb leads___ AVF, AVR, AVL F. Amplification___ V1 through V6 G. Centering control___ Increases signal H. Stylus temperature controlANSWER:HGFEDCBASuperbly Matched!21-*Preparing to Obtain an ECGProper technique essential Preparing the room and equipmentOther electrical equipment turned offQuiet room, comfortable temperatureCheck machineWarm upAdequate paper21-*Preparing to Obtain an ECG (cont.)Preparing the patientIntroduce yourselfExplain the procedureAnswer questionsEnsure patient comfortPerform ECG procedure21-*Applying the Electrodes and the Connecting WiresElectrodes – disposable are most commonPositioning electrodes Use consistent techniqueLimb electrodes – place at same level Precordial electrodes – specific intercostal spacesPrecordial Lead Placement21-*Applying the Electrodes and the Connecting Wires (cont.)Attaching wiresNumbers and letters correspond to those for electrodesConnect limb wires firstPrecordial in same sequence as electrodesAvoid tension on wires21-*Operating the ElectrocardiographStandardizeRun the ECGAutomaticManualMultiple-channelCheck the tracingClear/free from artifact21-*Apply Your KnowledgeIn addition to making sure the room is comfortable for the patient and the ECG machine is ready, what else should you do to prepare for performing an ECG?ANSWER: All other electrical equipment in the room should be turned off.Electrodes are placed at how many positions on the body?ANSWER: Ten: four limb and six chest positions.21-*Apply Your KnowledgeWhat should you do just prior to running the ECG to see if the machine needs adjusting? What should you do upon completion of the test?ANSWER: Standardize the electrocardiograph prior to running the tracing. Upon completion of the ECG, you should check the tracing to be sure is it clear and free from artifact.21-*Troubleshooting ArtifactsCausesImproper techniquePoor conductionOutside interferenceImproper handling21-*Troubleshooting Artifacts (cont.)Wandering baseline – somatic interference or mechanical problemsFlat line – loose or disconnected wireExtraneous marks – careless handling21-*Troubleshooting Artifacts (cont.)Causes AC interference – machine picks up current from other electrical equipmentSomatic interference – muscle movementIdentifying source of interferenceCheck tracings for leads I, II, and IIIIf unable to identify source, stop and notify supervisor of problemLeave patient connected21-*Completing the ProcedureAcceptable tracingLabel properlyDisconnect wires from electrodesRemove electrodes/wipe off electrolyte Assist patient upPrepare room appropriatelyMount tracing if necessary21-*Apply Your KnowledgeWhat are four general causes of artifacts?ANSWER: They are improper technique, poor conduction, outside interference, and improper handling of the tracing.What should you after running an ECG?ANSWER: After making sure the tracing is acceptable, you should label it properly, disconnect wires from electrodes, remove electrodes and wipe off electrolyte, assist patient up, and prepare the room appropriately for the next patient.Bravo!21-*Interpreting the ECG Not a medical assistant responsibilityKnowing how they are interpreted will enable you to recognize a problem requiring immediate attention21-*Interpreting the ECG (cont.)Heart rhythmRegularity of the heartbeatDistances between complexes and waves is normally consistentRhythm strip obtainedfrom lead II21-*Interpreting the ECG (cont.)Heart rate If regular – count QRS complexes in a 6-second strip and multiply by 10Irregularities Conduction abnormalitiesReaction to medication21-*Interpreting the ECG (cont.) Intervals and segmentsVariations in length and positionConduction disturbancesMyocardial infarctionsElectrolyte disturbancesWave changes – normally similar in each lead21-*Interpreting the ECG (cont.)Cardiac arrhythmias – irregularities in heart rhythmVentricular fibrillation – life-threatening with no cardiac outputPremature ventricular contractions – heartbeats that originate from the ventriclesBundle branch blocks – impulse through the heart is slowed or blocked Atrial fibrillation – electrical disturbance in the atria and/or AV node 21-*Apply Your KnowledgeMatching (may be used more than once): ___ Number of QRS complexes in 6 sec x 10 A. V-fib___ Cannot identify “P” waves B. Heart rhythm___ Produces no cardiac output C. Bundle branch block___ Originates in ventricles D. Atrial fibrillation___ Slows or stops impulse E. Heart beat___ Multiple impulses from sites outside SA node F. PVC___ “Saw-tooth” image___ Regularity of heart beat___ Due to irritable of ventricular heart muscleFFEDAADCBANSWER:21-*Exercise ElectrocardiographyStress test – measures the heart’s response to a constant or increasing workload UsesDetermine how a diseased heart is functioningScreen a patient for heart diseaseDetermine patient’s ability to start an exercise program21-*Ambulatory ElectrocardiographyResting ECG may not show abnormalitiesHolter monitorMonitors heart over a 24-hour period of normal activityUsesDiagnosis Evaluate status post-MIPatient educationRecord activitiesWhat to avoidHow to check monitor21-*Ambulatory Electrocardiography (cont.)Connecting the patient3 or 5 electrodesPrep skin prior to placingTape in place to eliminate tension and ensure that electrodes stay in place for entire time of testingPut fresh battery in the machineCheck tapeEnsure that machine is turned on21-*Apply Your KnowledgeWhat is the purpose for stress testing and Holter monitor testing?ANSWER: Stress testing is used to measure the heart’s response to a constant or increasing workload. A Holter monitor is used to obtain a tracing over a period of time when a resting ECG shows no abnormalities. Both are used for diagnosing cardiac conditions or for monitoring current treatments and medications.Correct!21-*Anatomy of the Respiratory SystemNosePharynxLarynxTrachea Two bronchiBronchiolesAlveoli21-*Physiology of the Respirator SystemExternal respiration – alveoli VentilationInspirationExpiration DiffusionInternal respiration (perfusion) – exchange of O2 and CO2 between blood and tissues 21-*Pulmonary Function TestingEvaluates lung volume and capacityUsesEvaluate of shortness of breath Detect and classify of pulmonary disordersEvaluate effectiveness of treatments 21-*SpirometryMeasures air taken in by and expelled by the lungs Forced vital capacity (FVC) – greatest volume of air that can be expelled with a rapid, forced expirationTypes of spirometers:Computerized Mechanical21-*Performing SpirometryTechnique similar for all types – be consistentPatient preparationInform the patient about conditions and activities that could affect the test accuracyExplain procedure and its purposeExplain the need for a nose clipBe sure patient forms a tight seal around the mouthpiece Position the patient properlyDemonstrate correct procedure21-*Performing Spirometry (cont.)Performing the maneuverUrge patient to blow hard and to continue blowing Provide feedback on performanceObtain three acceptable maneuversObserve the patient’s symptomsNotify physician immediately if symptoms occur21-*Performing Spirometry (cont.)Determining effectiveness of medicationsPerform test before patient takes medication for dayRepeat after patient takes the medicationSpecial considerationsUncooperative patientsPatients who do not understandPatients who cannot follow directionsPatients who cannot perform the procedure21-*Performing Spirometry (cont.)Calibration Daily – keep logbookCalibration syringe – standardized measuring instrumentDetect leaks – check time/volume graphResultsEvaluate ventilatory functionScreening for pulmonary disordersSeverity of problemsResponse to therapy or medication Infection controlClean equipment after each patientDiscard disposable supplies appropriatelyWash hands before and after each use21-*Peak Expiratory Flow Rate Determines amount of air that can be quickly forced from the lungsPeak flow meter Reveals narrowing of airways before an asthma attackPeak flow zonesDifferent for each patientGreen zone – good control of asthmaYellow zone – large airways are beginning to narrowRed zone – medical emergency21-*Pulse OximetryNon-invasive measurement of the oxygen saturation in arterial bloodHemoglobin absorbs infrared lightMeasures amount of light absorbedHypoxemia – less than 95%Uses Pulmonary and cardiac conditionsPostoperativelySleep apnea21-*Apply Your KnowledgeWhat is the purpose of PFTs?ANSWER: To evaluate lung volume and capacity.What is FVC?ANSWER: It is forced vital capacity: the greatest volume of air that can be expelled with a rapid, forced expiration. It is the measurement of the volume of air expelled and amount of time taken to expel it.21-*Apply Your KnowledgeJoey Jackson called to ask about taking his asthma medicine. He said he has been using his peak flow meter and the readings have been in his yellow zone. What do you tell him?ANSWER: This means that his large airways are beginning to narrow and that he should take his medication as prescribed.Joey decided to come to the office and you check his oxygen saturation with the pulse oximeter. The reading was 93%. What does this mean and what should you do?ANSWER: Joey is hypoxemic. You need to notify the physician and document findings.YIPPEE!4 for 421-*In Summary21.1 The heart is a muscular pump that circulates blood throughout the body. There are two upper chambers (atria) and two lower chambers (ventricles). Contraction of the atria followed by contraction of the ventricles moves the blood. 21.2 The conduction system of the heart is responsible for the electrical pathway that occurs during a heartbeat. The pathway begins with the SA node and travels through the AV node – bundle of HIS – right and left bundle branches and ends with the Purkinje fibers.21-*In Summary (cont.)21.3 The electrical impulses are represented in wave forms or deflections. Each deflection is labeled by letters PQRSTU and represents a part of the pattern.21.4 The electrocardiograph consists of the following components: electrodes, which detect and conduct electrical impulses to the electrocardiograph; amplifier, which increases the signal, making the heartbeat visible; stylus, which records the movement on the ECG paper; leads, combinations of electrodes, each providing different views of the electrical activity of the heart; and ECG paper, special heat-sensitive paper used for recording the ECG tracing.21-*In Summary (cont.)21.5 The limb leads are placed on the fleshy part of the upper arms and lower legs. The precordial leads are placed across and down the left side of the chest in the 4th and 5th intercostal space. All leads must be placed in a standard and concise manner.21.6 The steps in obtaining an accurate ECG include: identifying the patient; properly placing the limb and chest electrodes; attaching the lead wires; entering the patient data into the ECG machine; running the tracing; checking the tracing for artifacts; disconnecting the patient from the lead wires and removing electrodes; and assisting the patient as required.21-*In Summary (cont.)21.7 Artifacts that can occur during ECG testing include: AC interference – Caused by small amounts of electricity given off by other pieces of equipment in the room and picked up by the ECG machine. This can be corrected by turning off or unplugging other appliances in the room. Flat line – Caused by a loose or disconnected wire, or two wires that are switched. This can be corrected by checking and correcting lead placement. Somatic interference – Caused by patient muscle movement. This can be corrected by reminding the patient to remain still, keeping the patient warm, and placing the limb electrodes closer to the trunk of the body. Wandering baseline – Caused by somatic interference, mechanical problems, or improper electrode application. This can be corrected by reminding the patient to remain still, removing any oil or lotion from the patient’s skin before applying the electrodes, reapplying the electrodes, or uncrossing any crossed electrodes.21-*In Summary (cont.)21.8 The ECG is interpreted by assessing the heart rhythm, heart rate, the length and position of intervals and segments and any wave changes that occur. 21.9 A medical assistant should recognize abnormal heart rhythms such as premature ventricular contractions, ventricular fibrillation, and atrial fibrillation.21.10 Exercise electrocardiography is referred to as stress testing. This measures the efficiency of the heart during constant or increasing workload. 21-*In Summary (cont.)21.11 A Holter monitor is used to measure the heart’s activity over a 24-hour period and when the patient has intermittent chest pain or discomfort and a normal ECG and stress test.21.12 Forced vital capacity is the measurement of the greatest volume of air expelled when a patient performs a rapid, forced expiration. The lung’s ability to function is measured by the volume of air expelled and the time taken to perform maneuver.21.13 Accurate spirometry testing requires proper patient positioning, coaching the patient during the procedure, obtaining three acceptable maneuvers, and recording the results in the patient’s chart. 21-*In Summary (cont.)21.14 A peak expiratory flow rate is obtained by having the patient sit or stand using good posture, take in as deep a breath as possible, and blow out through the peak flow meter as fast and as hard as possible three times. The highest reading of the three is the peak flow rate and should be recorded in the patient’s chart.21.15 Pulse oximetry testing is performed by applying the pulse oximeter to the patient’s finger or toe, attaching the sensor cable to the oximeter, turning the oximeter on, setting the alarm limits for high and low oxygen saturations, and reading the patient’s oxygen saturation levels. The oxygen saturation levels should be recorded in the patient’s chart.21-*End of Chapter 21As the arteries grow hard, the heart grows soft.~ H. L. Mencken