Y khoa - Dược - Chapter 49: Electrocardiography and pulmonary function testing

49.1 Discuss the medical assistant's role in electrocardiography and pulmonary function testing. 49.2 Explain the basic principles of electrocardiography and how it relates to the conduction system of the heart. 49.3 Identify the components of an electrocardiograph and what each does. 49.4 Carry out the steps necessary to obtain an ECG.

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49Electrocardiography and Pulmonary Function Testing49.1 Discuss the medical assistant's role in electrocardiography and pulmonary function testing. 49.2 Explain the basic principles of electrocardiography and how it relates to the conduction system of the heart. 49.3 Identify the components of an electrocardiograph and what each does. 49.4 Carry out the steps necessary to obtain an ECG.Learning Outcomes49.5 Summarize exercise electrocardiography and echocardiography.49.6 Explain the procedure of Holter monitoring.49.7 Carry out the various types of pulmonary function tests.49.8 Describe the procedure for performing pulse oximetry testing.Learning OutcomesIntroductionCardiac testingElectrocardiogramHolter monitoring Stress testing Respiratory testing – pulmonary function testingThe Medical Assistant’s Role in Electrocardiography and Pulmonary Function TestingMedical assistant may perform ElectrocardiographyPulmonary function tests (PFTs)Diagnostic reasons Part of general examBasic Principles of ElectrocardiographyHeartbeats produce electrical current Resting cardiac cell – polarized Depolarization Occurs when cell loses polarityElectrical impulse initiates contractionImpulse detected by electrodesBasic Principles of ElectrocardiographyDepolarization Repolarization – electrical recoveryPolarized stateCardiac cycle – sequence of contraction and relaxationThe Basic Pattern of the ElectrocardiogramElectrocardiogram (ECG) produces the electrocardiographTracing of waves and lines produced by the cardiac cycleDeflections Peaks and valleys Sections labeled PQRSTUTo exampleApply Your KnowledgeWhat two procedures might the medical assistant preform?ANSWER: Electrocardiography and pulmonary function testing.What is the term for the depolarization, repolarization, and polarized state sequence?ANSWER: The cardiac cycle.The ElectrocardiographImpulse is detected by electrodesTransmitted by insulated wiresAmplified by the electrocardiograph machineStylus – records the movementLeads – views of electrical activity Types of ElectrocardiographsStandard – 12-lead electrographSingle-channelMultichannelElectrodes and Electrolyte ProductsElectrolyte is needed to enhance transmission of electric currentElectrodes are placedOne on each armOne on each legSix on chest LeadsLimb leads Three standard leads Bipolar Designation – I, II, IIIThree augmented viewsUnipolar Amplified Designation – AVF, AVR, AVLLeadsPrecordial leadsUnipolarDesignated V1 through V6 ECG PaperStandardized pattern of small and large squares Horizontal axis – time in secondsVertical axis – voltage (mV)The Electrocardiograph ControlsStandardization controlSpeed selectorSensitivity control Lead selectorThe Electrocardiograph ControlsCentering controlLine controlOn/Off switchApply 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. Line controlANSWER:HGFEDCBASuperbly Matched!Performing an ECGProper technique essential Preparing the room and equipmentTurn off other electrical equipmentQuiet room, comfortable temperatureCheck machineWarm upAdequate paperPerforming an ECG (cont.)Preparing the patientIntroduce yourselfExplain the procedureAnswer questionsEnsure patient comfortPerform ECG procedureApplying the Electrodes and the Connecting WiresElectrodesPositioning electrodes Use consistent techniqueLimb electrodes ~ place at same level Precordial electrodes ~ specific intercostal spacesApplying the Electrodes and the Connecting Wires (cont.)Attaching wiresNumbers and letters correspond to electrodesConnect limb wires firstPrecordial in same sequence as electrodesAvoid tension on wiresOperating the ElectrocardiographStandardizeRun the ECGAutomaticManualMultiple-channelCheck the tracingClearFree from artifactSource: Courtesy of Cardiac Science Corporation, Milton, WisconsinTroubleshooting: Artifacts and Other ProblemsArtifacts Improper techniquePoor conductionOutside interferenceImproper handlingWandering baselineSource: Courtesy of Cardiac Science Corporation, Milton, Wisconsin.Troubleshooting: Artifacts and Other Problems (cont.)Flat line – loose or disconnected wireExtraneous marks – careless handlingSource: Courtesy of Cardiac Science Corporation, Milton, Wisconsin.Source: Courtesy of Cardiac Science Corporation, Milton, Wisconsin.Troubleshooting: Artifacts and Other Problems (cont.)Causes AC interference Somatic interferenceSource: Courtesy of Cardiac Science Corporation, Milton, Wisconsin.Troubleshooting: Artifacts and Other Problems (cont.)Identifying source Check tracings for leads I, II, and IIIIf unable to identify source, stop and notify supervisor of problemLeave patient connectedCompleting the ProcedureAcceptable tracingLabel tracing properlyDisconnect wires from electrodesRemove electrodes/wipe off electrolyte Assist patient as neededPrepare room appropriatelyMount tracing if necessaryCompleting the Procedure (cont.)Interpreting the ECG Not a medical assistant responsibilityBe able recognize a problem requiring immediate attentionCompleting the Procedure (cont.)Interpreting the ECG – heart rhythmRegularity of the heartbeatDistances between complexes and waves is normally consistentRhythm strip – lead IITo exampleCompleting the Procedure (cont.)Heart rate – count QRS complexes in a 6-second strip and multiply by 10Intervals and Segments – look for variations in length and positionWave changes – should be similar appearance in each leadTo exampleCompleting the Procedure (cont.)Cardiac Arrhythmias Ventricular fibrillation Premature ventricular contractions Atrial fibrillationApply Your KnowledgeElectrodes are placed at how many positions on the body?ANSWER: Ten: four limb and six chest positions.What 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.ElectrifyinglyGreat!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.What are four general causes of artifacts?ANSWER: They are improper technique, poor conduction, outside interference, and improper handling of the tracing.Exercise Electrocardiography (Stress Testing) and EchocardiographyExercise electrocardiography or stress test – measures response to exerciseEchocardiography Ultrasound Resting or post exerciseExercise ElectrocardiographyUsesProcedure – monitoring during exerciseMedical assistantPrepare and monitor patientBe sure consent form is signedPatient instructionsEchocardiographyPurposeTypesTransthoracicTransesophagealDopplerStress echo Medical assistantBe sure consent form is signedPatient instructionsAmbulatory Electrocardiography (Holter Monitoring)Monitors heart over a 24-hour period of normal activityFunction 24 hour recordingTracing irregularities compared to events in diaryPatient educationKeep diaryWhat to avoidHow to check monitorApply Your KnowledgeWhat is the purpose for stress testing, echocardiogram, and Holter monitor testing?ANSWER: Stress testing is used to measure the heart’s response to a constant or increasing workload. An echocardiogram shows the working heart valves and chambers and how well the blood moves through the heart.A Holter monitor is used to obtain a tracing over a period of time when a resting ECG or stress test shows no abnormalities. All are used for diagnosing cardiac conditions or for monitoring current treatments and medications.Correct!Pulmonary Function TestingEvaluates lung volume and capacityUsesEvaluate of shortness of breath Detect and classify of pulmonary disordersEvaluate effectiveness of treatments SpirometryMeasures breathing capacitySpirometer Mouthpiece Mechanism to measure volumeMeans of calculating and printing resultsForced vital capacity Performing SpirometryPatient preparationInform the patient about conditions and activities that could affect the test accuracyExplain procedure and its purposePosition the patient properlyExplain and demonstrate correct procedurePerforming Spirometry (cont.)Performing the maneuverForcefully coach and provide feedbackObtain three acceptable maneuversObserve the patient’s symptomsNotify physician if symptoms occurPerforming Spirometry (cont.)Medication effectivenessPerform test before patient takes medication Repeat after patient takes the medicationPerforming Spirometry (cont.)Medication effectivenessPerform test before patient takes medication Repeat after patient takes the medicationSpecial considerationsUncooperative patientsPatients who do not understandPatients who cannot follow directionsPatients who cannot perform the procedurePerforming Spirometry (cont.)Calibration Daily ~ keep logbookCalibration syringe Infection controlClean after patient testingDispose of items appropriatelyResults of testingPeak Expiratory Flow Rate (PEFR)Peak flow meter Reveal narrowing of airways prior to an asthma attackPhysician determines peak flow zonesPeak Expiratory Flow Rate (PEFR)Pulse OximetryMeasurement of the oxygen saturation Measures amount of light absorbed by hemoglobinHypoxemia ~ less than 95%Uses Pulmonary and cardiac conditionsPostoperativelySleep apneaApply Your KnowledgeWhat is the purpose of PFTs?ANSWER: To evaluate lung volume and capacity.What does successful spirometry testing depend on?ANSWER: On proper patient preparation and consistent technique in preforming the procedure and analyzing the results.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.Very good!In Summary49.1 As a medical assistant, you will be responsible for preparing the patient for ECG and pulmonary function tests, maintaining the equipment used for these tests, and performing them. In Summary (cont.)49.2 The heart’s conduction system is responsible for the electrical pathway that occurs during a heartbeat. The pathway begins with the SA node, travels through the AV node, Bundle of HIS, Right and Left bundle branches, and ends with the Purkinje fibers. This electrical energy pathway is measured with an electrocardiograph and a tracing of the impulses is produced. The electrical impulses are represented in wave forms or deflections. Each deflection is labeled by letters PQRSTU and represents a part of the pattern.In Summary (cont.)49.3 The electrocardiograph consists of the following components: electrodes, amplifier, stylus, leads, and ECG paper. 49.4 The steps in obtaining an accurate ECG include preparing the room and equipment, 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 the electrodes, and assisting the patient as required.In Summary (cont.)49.5 Exercise electrocardiography is referred to as stress testing. This measures the efficiency of the heart during constant or increasing workload. Echocardiography uses ultrasound to create a picture of the moving heart. This can be done while the patient is resting or after exercise.49.6 A Holter monitor is used to measure the heart’s activity over a 24-hour period. This is used when the patient has intermittent chest pain or discomfort and a normal ECG and stress test. In Summary (cont.)49.7 Forced vital capacity is the measurement of the greatest volume of air expelled when a patient performs a rapid, forced expiration. Accurate spirometry testing includes proper patient positioning, coaching the patient during the procedure, obtaining three acceptable maneuvers, and recording the results in the patient’s chart. 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. In Summary (cont.)49.8 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.End of Chapter 49As the arteries grow hard, the heart grows soft.~ H. L. Mencken52-*Apply Your KnowledgeWhat 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.Fantastic!
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