Medical assisting Administrative and clinical procedures (5e) Chapter 49 Electrocardiography and pulmonary function testing

This chapter introduces you to the electrocardiograph instrument and how to administer an electrocardiogram. You will also learn how to apply electrocardiograph electrodes and wires, operate the instrument, and troubleshoot problems that can occur while recording the hearts electrical activity.

Electrocardiography

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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.

Learning Outcomes

49.5 Summarize exercise electrocardiography

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and Pulmonary Function Testing

• Medical assistant may perform

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Basic Principles of Electrocardiography

• Heartbeats produce electrical current

• Resting cardiac cell – polarized

• Depolarization

– Occurs when cell loses polarity

– Electrical impulse initiates contraction

– Impulse detected by electrodes

Basic Principles of Electrocardiography

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The Basic Pattern of the

• Peaks and valleys

• Sections labeled PQRSTU

To example

Apply Your Knowledge

1 What two procedures might the medical

assistant preform?

ANSWER: Electrocardiography and pulmonary function testing.

2 What is the term for the depolarization,

repolarization, and polarized state sequence?

ANSWER: The cardiac cycle.

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The Electrocardiograph

• Impulse is detected by electrodes

• Transmitted by insulated wires

• Amplified by the electrocardiograph machine

• Stylus – records the movement

• Leads – views of electrical activity

Types of Electrocardiographs

• Standard – 12-lead electrograph

• Single-channel

• Multichannel

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Electrodes and Electrolyte Products

• Electrolyte is needed to enhance transmission of

electric current

• Electrodes are placed

– One on each arm

– One on each leg

– Six on chest

• Limb leads

– Three standard leads

• Bipolar

• Designation – I, II, III

– Three augmented views

• Unipolar

• Amplified

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ECG Paper

• Standardized pattern of small and large squares

• Horizontal axis – time in seconds

• Vertical axis – voltage (mV)

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The Electrocardiograph Controls

• Standardization control

• Speed selector

• Sensitivity control

• Lead selector

The Electrocardiograph Controls

• Centering control

• Line control

• On/Off switch

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Apply Your Knowledge

Matching:

_ 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 control

Performing an ECG

• Proper technique essential

• Preparing the room and equipment

– Turn off other electrical equipment

– Quiet room, comfortable temperature

– Check machine

• Warm up

• Adequate paper

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Performing an ECG (cont.)

• Preparing the patient

– Introduce yourself

– Explain the procedure

– Answer questions

– Ensure patient comfort

– Perform ECG procedure

Applying the Electrodes and the

Connecting Wires

• Electrodes

• Positioning electrodes

– Use consistent technique

– Limb electrodes ~ place at same level

– Precordial electrodes ~

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Applying the Electrodes and the

• Attaching wires

– Numbers and letters correspond to electrodes

– Connect limb wires first

– Precordial in same sequence as electrodes

– Avoid tension

on wires

Operating the Electrocardiograph

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Troubleshooting: Artifacts and Other

• Wandering

baseline

Source: Courtesy of Cardiac Science Corporation, Milton, Wisconsin.

Troubleshooting: Artifacts and Other

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Source: Courtesy of Cardiac Science Corporation, Milton, Wisconsin.

Troubleshooting: Artifacts and Other

Problems (cont.)

• Causes

– AC interference – Somatic interference

Source: Courtesy of Cardiac Science Corporation, Milton, Wisconsin.

Troubleshooting: Artifacts and Other

Problems (cont.)

• Identifying source

– Check tracings for leads I, II, and III

– If unable to identify source, stop and notify

supervisor of problem – Leave patient connected

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Completing the Procedure

• Acceptable tracing

– Label tracing properly

– Disconnect wires from electrodes

– Remove electrodes/wipe off electrolyte

– Assist patient as needed

– Prepare room appropriately

• Mount tracing if necessary

Completing the Procedure (cont.)

• Interpreting the ECG

– Not a medical assistant responsibility

– Be able recognize a problem requiring

immediate attention

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Completing the Procedure (cont.)

• Interpreting the ECG – heart rhythm

– Regularity of the heartbeat

– Distances between complexes and waves is

normally consistent – Rhythm strip – lead II

To example

Completing the Procedure (cont.)

• Heart rate – count QRS complexes in a 6-second

strip and multiply by 10

• Intervals and Segments – look for variations in

length and position

• Wave changes – should be similar appearance in

each lead

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Completing the Procedure (cont.)

• Cardiac Arrhythmias

– Ventricular fibrillation

– Premature ventricular contractions

– Atrial fibrillation

Apply Your Knowledge

1 Electrodes are placed at how many positions on the

body?

ANSWER: Ten: four limb and six chest

positions.

2 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

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Apply Your Knowledge

3 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.

ANSWER: They are improper technique, poor conduction, outside

interference, and improper handling of the tracing.

Exercise Electrocardiography (Stress

Testing) and Echocardiography

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– Prepare and monitor patient

– Be sure consent form is signed

– Patient instructions

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Ambulatory Electrocardiography (Holter

• Patient education

– Keep diary – What to avoid – How to check monitor

Apply Your Knowledge

What 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

Correct

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Pulmonary Function Testing

• Evaluates lung volume and capacity

• Uses

– Evaluate of shortness of breath

– Detect and classify of pulmonary disorders

– Evaluate effectiveness of treatments

– Mechanism to measure volume

– Means of calculating and printing results

• Forced vital capacity

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Performing Spirometry

• Patient preparation

– Inform the patient about conditions and

activities that could affect the test accuracy – Explain procedure and its purpose

– Position the patient properly

– Explain and demonstrate correct procedure

Performing Spirometry (cont.)

• Performing the maneuver

– Forcefully coach and provide feedback

– Obtain three acceptable maneuvers

– Observe the patient’s symptoms

– Notify physician if symptoms

occur

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Performing Spirometry (cont.)

• Medication effectiveness

– Perform test before patient takes medication

– Repeat after patient takes the medication

Performing Spirometry (cont.)

• Medication

effectiveness

– Perform test before

patient takes medication

– Repeat after patient

takes the medication

• Special

considerations

– Uncooperative patients

– Patients who do not understand

– Patients who cannot follow directions

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Performing Spirometry (cont.)

• Calibration

– Daily ~ keep

logbook – Calibration

• Results of testing

Peak Expiratory Flow Rate (PEFR)

• Peak flow meter

– Reveal narrowing of airways prior to an

asthma attack – Physician determines peak flow zones

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Peak Expiratory Flow Rate (PEFR)

Pulse Oximetry

• Measurement of the oxygen saturation

– Measures amount of light absorbed by

hemoglobin – Hypoxemia ~ less than 95%

• Uses

– Pulmonary and cardiac

conditions

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Apply Your Knowledge

1 What is the purpose of PFTs?

ANSWER: To evaluate lung volume and capacity.

2 What does successful spirometry testing depend on?

ANSWER: On proper patient preparation and

consistent technique in preforming the procedure and

analyzing the results.