Lecture Medical assisting: Administrative and clinical procedures with anatomy and physiology (4/e) – Chapter 52

Chapter 52 - 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 heart''s electrical activity.

Electrocardiography

and Pulmonary

Function Testing

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Learning Outcomes

52.1 Describe the anatomy and physiology of the

heart.

52.2 Explain the conduction system of the heart.

52.3 Describe the basic patterns of an

electrocardiogram (ECG).

52.4 Identify the components of an

electrocardiograph and what each does.

precordial electrodes correctly.

52.6 Describe in detail how to obtain an ECG.

52.7 Identify the various types of artifacts and

potential equipment problems and how to correct them.

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52.8 Identify how the ECG is interpreted.

52.9 Identify common arrhythmias.

52.10 Summarize exercise electrocardiography.

52.11 Explain the procedure of Holter

monitoring.

52.12 Describe forced vital capacity.

52.14 Describe the procedure for obtaining a

performing peak expiratory flow rate.

52.15 Describe the procedure for performing pulse

oximetry testing.

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the heart and respiratory system

– Graphic recording of the

electrical impulses of the heart

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• Pulmonary function tests

– Measure and evaluate a

patient’s lung capacity and volume

– Right – receives blood from the body, sends it

to the lungs – Left – receives blood from the lungs, sends it

out to all parts of the body

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Physiology of the Heart

• Systole – contraction phase

• Diastole – 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.

– Controlled by specialized tissues

in the heart wall that transmit

electrical impulses

– Impulses cause muscle to contract and relax

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Relay impulse to Purkinje fibers

Located in ventricle walls Contraction of ventricles

– Prior to polarized (resting) state

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• Basic pattern of the ECG

– Waves ( deflections ) are labeled P, Q, R, S,

T, U

True 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 F

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stylus

– Standard machine –

12-lead, which records

12 different views at once

– Single channel –

one lead and records only one view

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• Electrodes and

electrolyte products

– Electrolyte – enhances

transmissions of electric

current

– Electrodes

• Ten areas of the body

– Right and left arms – Right and left legs – Six locations on the chest

• Enables physician to pinpoint origin of

problems

– Provide different images of electrical activity

– Marked automatically on the ECG

– Limb leads

• Three standard – I, II, III

• Three augmented – AVF, AVR, AVL

– Precordial leads – V1 through V6

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• ECG paper

– Single or multichannel

available– Heat- and pressure-

sensitive– Standardized to permit

uniform interpretation– Vertical axis – strength

of impulse (millivolt)– Horizontal axis – time

0.04 sec

5 mm (0.5 mV)

1 mm (0.1 mV)

1 mm

5 mm

0.2 sec

– Lead selector –

enables selection of a single lead

– Centering control – adjusts position of stylus

– Line control – adjusts darkness of line

– 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 Stylus temperature control

• Preparing the room and equipment

– Other electrical equipment turned off

– Quiet room, comfortable temperature

– Check machine

• Warm up

• Adequate paper

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• Preparing the patient

– Introduce yourself

– Explain the procedure

– Answer questions

– Ensure patient comfort

– Perform ECG procedure

disposable are most

common

• Positioning electrodes

– Use consistent

technique– Limb electrodes –

place at same level – Precordial electrodes –

specific intercostal spaces

Precordial Lead Placement

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Wires (cont.)

• Attaching wires

– Numbers and letters

correspond to those for electrodes

– Connect limb wires

first– Precordial in same

sequence as electrodes– Avoid tension on wires

• Run the ECG

– Automatic

– Manual

– Multiple-channel

– Clear/free from artifact

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Apply Your Knowledge

1. In 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.

2. Electrodes are placed at how many positions on the

body?

ANSWER: Ten: four limb and six chest

positions.

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.

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Troubleshooting Artifacts (cont.)

• Causes

– AC interference –

machine picks up current from other electrical

equipment

– Somatic

interference – muscle movement

– Leave patient connected

– Label properly– Disconnect wires from electrodes

– Remove electrodes/wipe off electrolyte

– Assist patient up– Prepare room appropriately

• Mount tracing if necessary

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Apply Your Knowledge

1. What are four general causes of artifacts?

ANSWER: They are improper technique, poor

conduction, outside interference, and improper handling

of the tracing.

2. 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!

• Knowing how they are interpreted will

enable you to recognize a problem

requiring immediate attention

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• Heart rhythm

– Regularity of the heartbeat

– Distances between complexes and waves is

normally consistent – Rhythm strip obtained

from lead II

– If regular – count QRS complexes in a

6-second strip and multiply by 10

– Irregularities

• Conduction abnormalities

• Reaction to medication

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• Intervals and segments

– Variations in length and position

– Ventricular fibrillation – life-threatening with no cardiac

output– Premature ventricular contractions – heartbeats that

originate from the ventricles– Bundle branch blocks – impulse through the heart is

slowed or blocked – Atrial fibrillation – electrical disturbance in the atria

and/or AV node

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Apply Your Knowledge

Matching (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 muscleF

the heart’s response to a

disease – Determine patient’s ability

to start an exercise program

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– 3 or 5 electrodes

– Prep skin prior to placing

– Tape in place to eliminate tension and ensure

that electrodes stay in place for entire time of testing

– Put fresh battery in the machine

– Check tape

– Ensure that machine is turned on

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Apply Your Knowledge

What 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!

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Physiology of the Respirator System

• External respiration – alveoli

– Ventilation

• Inspiration

• Expiration

– Diffusion

• Internal respiration (perfusion) – exchange

of O2 and CO2 between blood and tissues

volume and capacity

• Uses

– Evaluate of shortness

of breath – Detect and classify of

pulmonary disorders– Evaluate effectiveness

of treatments

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Spirometry

• Measures 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

expiration

• Types of spirometers:

– Computerized

– Mechanical

• Patient preparation

– Inform the patient about conditions and activities

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

– Explain the need for a nose clip

– Be sure patient forms a tight seal around the

mouthpiece – Position the patient properly

– Demonstrate correct procedure

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– Urge patient to blow hard and to continue

blowing – Provide feedback on performance

– Obtain three acceptable maneuvers

– Observe the patient’s symptoms

– Notify physician immediately if symptoms

occur

effectiveness of

medications

– Perform test before

patient takes medication for day

– Repeat after patient

takes the medication

considerations

– Uncooperative patients

– Patients who do not understand

– Patients who cannot follow directions

– Patients who cannot perform the procedure

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• Calibration

– Daily – keep logbook

– Calibration syringe –

standardized measuring instrument

– Detect leaks – check

time/volume graph

• Results

– Evaluate ventilatory

function – Screening for pulmonary

disorders – Severity of problems

air that can be quickly

forced from the lungs

• Peak flow meter

airways are beginning

to narrow

– Red zone – medical emergency

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Pulse Oximetry

• Non-invasive measurement of the oxygen

saturation in arterial blood

– Hemoglobin absorbs infrared light

– Measures amount of light absorbed

– Hypoxemia – less than 95%

• Uses

– Pulmonary and cardiac conditions

– Postoperatively

– Sleep apnea

ANSWER: To evaluate lung volume and capacity.

2. 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.

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Apply Your Knowledge

3 Joey 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.

4 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.

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

52.2The 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

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52.3The electrical impulses are represented in wave forms

or deflections Each deflection is labeled by letters PQRSTU and represents a part of the pattern

52.4The 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

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

52.6The 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

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52.7Artifacts 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.

rhythm, heart rate, the length and position of intervals and segments and any wave changes that occur

52.9 A medical assistant should recognize abnormal heart

rhythms such as premature ventricular contractions, ventricular fibrillation, and atrial fibrillation

52.10 Exercise electrocardiography is referred to as stress

testing This measures the efficiency of the heart during constant or increasing workload