CHAPTER
52
Electrocardiography
and Pulmonary
Function Testing
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52-2
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.
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52-3
Learning Outcomes (cont.)
52.5 Explain how to position the limb and
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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52-4
Learning Outcomes (cont.)
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.
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52-5
Learning Outcomes (cont.)
52.13 Describe the procedure of performing
spirometry.
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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52-6
Introduction
• Patients often have cardiovascular
or respiratory problems
• Medical assistant
–
–
Perform screening and/or diagnostic
testing
Understand the anatomy and physiology of
the heart and respiratory system
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52-7
The Medical Assistant’s Role
• Electrocardiography
– Graphic recording of the
electrical impulses of the
heart
– Uses
• Evaluate symptoms of heart
disease
• Check effectiveness or side
effects of medications
• General examination
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52-8
The Medical Assistant’s Role (cont.)
• Pulmonary function tests
– Measure and evaluate a
patient’s lung capacity and
volume
– Uses
• Help detect and diagnose
pulmonary problems
• Monitor respiratory
disorders
• Evaluate effectiveness of
treatments
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52-9
Anatomy of the Heart
• Muscular double pump
– 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
• Four chambers
– Two atria
– Two ventricles
• Valves
• Septum
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52-10
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.
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52-11
Conduction System of the Heart
• Cardiac cycle
– Controlled by
specialized tissues
in the heart wall
that transmit
electrical impulses
– Impulses cause
muscle to contract
and relax
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52-12
Conduction System of the Heart (cont.)
SA Node
Pacemaker of
the heart
Sets rhythm of
contractions
AV Node
Bottom of right
atrium
Impulse delayed
slightly
Bundle of His
Located in septum
between ventricles
Bundle Branches
Relay impulse to
Purkinje fibers
Purkinje Fibers
Located in
ventricle walls
Contraction of
ventricles
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52-13
Conduction System of the Heart (cont.)
•
Electrocardiography
–
•
Transmission, magnitude,
and duration of electrical
impulses of the heart
Polarity
–
–
Having a positive and
negative pole
Resting cell
• Positive outside
• Negative inside
• Depolarization
– Impulse that initiates a
contraction
• Repolarization
– Period of electrical
recovery following
depolarization
– Prior to polarized (resting)
state
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52-14
Conduction System of the Heart (cont.)
• Basic pattern of the ECG
– Waves (deflections) are labeled P, Q, R, S,
T, U
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52-15
Apply Your Knowledge
True or False
ANSWER:
___
F The AV node is the heart’s pacemaker.
SA
F The medical assistant does not perform ECGs or PFTs.
___
may
___
T The bundle branches relay impulses to the Purkinje fibers in
the ventricles.
T The heart is resting in the polarized state.
___
___
T Depolarization initiates contractions of atria and ventricles.
___
F Repolarization occurs before depolarization.
following
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52-16
The Electrocardiograph
• Electrical impulses
are detected
through the skin
– Measures
– Amplifies – signal
is increased
– Records using the
stylus
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52-17
The Electrocardiograph (cont.)
• Types of
electrocardiographs
– Standard machine –
12-lead, which records
12 different views at
once
– Single channel –
one lead and records
only one view
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52-18
The Electrocardiograph (cont.)
• 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
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52-19
The Electrocardiograph (cont.)
• Leads
– 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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52-20
The Electrocardiograph (cont.)
• ECG paper
– Single or multichannel
available
0.04 sec
0.2 sec
– Heat- and pressuresensitive
1 mm
(0.1 mV)
– Standardized to permit
uniform interpretation
– Vertical axis – strength
of impulse (millivolt)
5 mm
(0.5 mV)
5 mm
1 mm
– Horizontal axis – time
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52-21
The Electrocardiograph (cont.)
• Controls
– Standardization
control
– Speed selector –
25mm/sec standard
– Sensitivity control –
adjusts height of
tracing
– Centering control –
adjusts position of
stylus
– Line control – adjusts
darkness of line
– On/Off switch
– Lead selector –
enables selection of a
single lead
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52-22
Apply Your Knowledge
Matching: ANSWER:
___
G Adjusts position of stylus
A. Vertical axis
___
B Adjusts height of tracing
B. Sensitivity control
___
H Adjusts darkness of tracing
C. Precordial leads
___
A Measures strength of impulse
D. Horizontal axis
___
D Measures time
E. Limb leads
___
E AVF, AVR, AVL
F. Amplification
___
C V1 through V6
G. Centering control
___
F Increases signal
H. Stylus temperature control
Superbly Matched!
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52-23
Preparing to Obtain an ECG
• Proper technique essential
• Preparing the room and equipment
– Other electrical equipment turned off
– Quiet room, comfortable temperature
– Check machine
• Warm up
• Adequate paper
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52-24
Preparing to Obtain an ECG (cont.)
• Preparing the patient
– Introduce yourself
– Explain the procedure
– Answer questions
– Ensure patient comfort
– Perform ECG procedure
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52-25
Applying the Electrodes and the Connecting
Wires
• Electrodes –
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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52-26
Applying the Electrodes and the Connecting
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
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52-27
Operating the Electrocardiograph
• Standardize
• Run the ECG
• Check the tracing
– Clear/free from
artifact
– Automatic
– Manual
– Multiple-channel
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52-28
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.
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52-29
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.
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52-30
Troubleshooting Artifacts
• Causes
– Improper technique
– Poor conduction
– Outside
interference
– Improper handling
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52-31
Troubleshooting Artifacts (cont.)
• Wandering
baseline – somatic
interference or
mechanical
problems
• Flat line – loose or
disconnected wire
• Extraneous marks
– careless handling
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52-32
Troubleshooting Artifacts (cont.)
• Causes
– AC interference –
machine picks up
current from other
electrical
equipment
– Somatic
interference –
muscle movement
• Identifying source
of interference
– 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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52-33
Completing the Procedure
• Acceptable tracing
– 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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52-34
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!
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52-35
Interpreting the ECG
• Not a medical assistant responsibility
• Knowing how they are interpreted will
enable you to recognize a problem
requiring immediate attention
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52-36
Interpreting the ECG (cont.)
• Heart rhythm
– Regularity of the heartbeat
– Distances between complexes and waves is
normally consistent
– Rhythm strip obtained
from lead II
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52-37
Interpreting the ECG (cont.)
• Heart rate
– If regular – count QRS complexes in a 6second strip and multiply by 10
– Irregularities
• Conduction abnormalities
• Reaction to medication
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52-38
Interpreting the ECG (cont.)
• Intervals and segments
– Variations in length and position
• Conduction disturbances
• Myocardial infarctions
• Electrolyte disturbances
• Wave changes –
normally similar in
each lead
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52-39
Interpreting the ECG (cont.)
• Cardiac arrhythmias – irregularities in heart rhythm
– 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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52-40
Apply Your Knowledge
Matching (may be used more than once):
ANSWER:
E Number of QRS complexes in 6 sec x 10
___
A. V-fib
___
D Cannot identify “P” waves
B. Heart rhythm
A Produces no cardiac output
___
C. Bundle branch block
___
F Originates in ventricles
D. Atrial fibrillation
___
C Slows or stops impulse
E. Heart beat
D Multiple impulses from sites outside SA node
___
F. PVC
___
A “Saw-tooth” image
___
B Regularity of heart beat
___
F Due to irritable of ventricular heart muscle
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52-41
Exercise Electrocardiography
• Stress test – measures
the heart’s response to a
constant or increasing
workload
• Uses
– Determine how a diseased
heart is functioning
– Screen a patient for heart
disease
– Determine patient’s ability
to start an exercise
program
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52-42
Ambulatory Electrocardiography
• Resting ECG may not show abnormalities
• Holter monitor
– Monitors heart over a
24-hour period of
normal activity
• Patient education
– Record activities
– What to avoid
– How to check monitor
– Uses
• Diagnosis
• Evaluate status post-MI
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52-43
Ambulatory Electrocardiography (cont.)
• Connecting the patient
– 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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52-44
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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52-45
Anatomy of the Respiratory System
•
•
•
•
•
•
•
Nose
Pharynx
Larynx
Trachea
Two bronchi
Bronchioles
Alveoli
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52-46
Physiology of the Respirator System
• External respiration – alveoli
– Ventilation
• Inspiration
• Expiration
– Diffusion
• Internal respiration (perfusion) – exchange
of O2 and CO2 between blood and tissues
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52-47
Pulmonary Function Testing
• Evaluates lung
volume and capacity
• Uses
– Evaluate of shortness
of breath
– Detect and classify of
pulmonary disorders
– Evaluate effectiveness
of treatments
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52-48
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
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52-49
Performing Spirometry
•
Technique similar for all types – be consistent
•
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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52-50
Performing Spirometry (cont.)
•
Performing the maneuver
– 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
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52-51
Performing Spirometry (cont.)
• Determining
effectiveness of
medications
– Perform test before
patient takes
medication for day
– Repeat after patient
takes the medication
• Special
considerations
– Uncooperative
patients
– Patients who do not
understand
– Patients who cannot
follow directions
– Patients who cannot
perform the procedure
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52-52
Performing Spirometry (cont.)
• Calibration
– Daily – keep logbook
– Calibration syringe –
standardized measuring
instrument
– Detect leaks – check
time/volume graph
• Results
• Infection control
– Clean equipment after
each patient
– Discard disposable
supplies appropriately
– Wash hands before and
after each use
– Evaluate ventilatory
function
– Screening for pulmonary
disorders
– Severity of problems
– Response to therapy or
medication
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52-53
Peak Expiratory Flow Rate
• Determines amount of • Peak flow zones
air that can be quickly
– Different for each
patient
forced from the lungs
• Peak flow meter
• Reveals narrowing of
airways before an
asthma attack
– Green zone – good
control of asthma
– Yellow zone – large
airways are beginning
to narrow
– Red zone – medical
emergency
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52-54
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
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52-55
Apply Your Knowledge
1.
What is the purpose of PFTs?
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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52-56
YIPPEE!
4 for 4
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.
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52-57
In Summary
52.1 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.
52.2 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.
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52-58
In Summary (cont.)
52.3 The electrical impulses are represented in wave forms
or deflections. Each deflection is labeled by letters
PQRSTU and represents a part of the pattern.
52.4 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.
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52-59
In Summary (cont.)
52.5 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.
52.6 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.
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52-60
In Summary (cont.)
52.7 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.
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52-61
In Summary (cont.)
52.8 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.
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.
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52-62
In Summary (cont.)
52.11 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.
52.12 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.
52.13 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.
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52-63
In Summary (cont.)
52.14 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.
52.15 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.
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52-64
End of Chapter 52
As the arteries
grow hard, the
heart grows soft.
~ H. L. Mencken
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.