Ch. 9: Cardiac Monitoring Flashcards
What is known as the pacemaker of the heart?
SA node
The sinoatrial node usually intiates about ____ impulses/min
75
Once an impulse has been initiated by the SA node, the impulse travels down to the ______________.
atrioventricular (AV) node
Where is the Bundle of His located?
Interventricular septum
After contraction, repolarization occurs, and the heart is in a resting state, what is this called?
Diastole
What is the term used for the heart in contraction?
Systole
The device to which the electrodes are attached is the _________________.
Electrocardiograph
The electrical activity of the heart recorded on graph paper is called the ____________ and may be displayed continuously on an ECG monitor, called an oscilloscope.
Electrocardiogram
State the order of the electrical conduction of the heart.
- SA node
- AV node
- Bundle of His
- Right/Left bundle branches
- Purkinje fibers
Standard 12-Lead ECG has how many lead systems?
3
The leads are placed on the right arm, left arm, and left leg.
Standard limb leads (1, positive pole; 2, negative pole; and ground)
Which limb lead measures the electrical potential between the right arm and left arm?
Limb lead I
Standard limb leads (1, positive pole; 2, negative pole; and ground)
Which limb lead measures the electrical potential between the right arm and left leg?
Limb lead II
Standard limb leads (1, positive pole; 2, negative pole; and ground)
Which limb lead measures the electrical potential between the left arm and left leg?
Limb lead III
Standard limb leads (1, positive pole; 2, negative pole; and ground)
Where is the ground limb lead placed?
Right leg
Precordial (chest) leads (six leads)
Lead 1 (V1) is positioned at the ________ intercostal space at the ________ border of the sternum.
Lead 1 (V1) is positioned at the fourth intercostal space at the right border of the sternum.
Lead 2 (V2) is positioned at the ________ intercostal space at the ________ border of the sternum.
Lead 2 (V2) is positioned at the fourth intercostal space at the left border of the sternum.
Where is Lead 3 (V3) positioned?
In a straight line between leads 2 and 4.
Where is Lead 4 (V4) positioned?
At the midclavicular line and at the fifth intercostal space.
Where is Lead 5 (V5) positioned?
At the anterior axillary line, level with lead 4 horizontally.
Where is Lead 6 (V6) positioned?
At the midaxillary line, level with leads 4 and 5 horizontally.
Long-term ECG Monitoring - 3 LEAD PLACEMENTS
Where is the first electrode placed?
Upper right side of the chest (-).
Long-term ECG Monitoring - 3 LEAD PLACEMENTS
Where is the second electrode placed?
Lower left side of the chest (+)
Long-term ECG Monitoring - 3 LEAD PLACEMENTS
Where is the third electrode placed?
It is used as a ground and may be attached to any location that is convenient.
The ECG paper is made up of very small squares, which represent ____ seconds horizontally.
0.04
The ECG paper is made up of very small squares, which represent ________ vertically (voltage axis).
0.5 mV
Is the P wave a postive or negative wave?
Positive
What does the P wave represent?
Atrial depolarization (contraction)
What is the duration of the P wave?
0.06 to 0.10 seconds
Is the Q wave a positive or negative wave?
Negative
An absence of this wave may be seen even in healthy people. What is this wave called?
Q wave
Is the R wave a positive or negative wave?
Positive
Is the S wave a positive or negative wave?
Negative
What does QRS complex measure?
Ventricular depolarization
What is the duration of the QRS complex?
0.06 to 0.10 seconds
In what instances is a wide QRS complex seen?
- Right bundle branch block
- Premature ventricular contractions (PVCs)
What does the T wave represent?
Ventricular repolarization
What does an inverted T wave indicate?
Coronary artery disease
How is the PR interval measured?
Measured from the beginning of the P wave to the beginning of the Q wave.
What is the duration of the PR interval?
0.12 to 0.20 seconds.
What represents the time it takes for the impulse to travel from the SA node through the AV node?
PR Interval
How is the ST segment measured?
Measured from the end of the S wave to the beginning of the T wave.
____________ measures the time that is required for ventricular repolarization to begin.
ST segment
The ST segment may be elevated above the baseline or depressed below the baseline. What is this an indication of?
Cardiac ischemia
Cardiac ischemia results from a decreased amount of oxygenated blood delivered to the left ventricle because of narrowed coronary arteries. If the blood supply is not restored, ventricular muscle may die; this is called infarction. ST segment elevation or depression is a sign of coronary artery disease.
Cardiac impulse travels to the AV node, bundle of His, and the Purkinje fibers, which are represented on the ECG as the what?
PR interval
Ventricular repolarization is represented on the ECG as the __________.
ST segment and T wave
How do you calculate the HR on an ECG?
Count the number of R waves in a 6-second period and multiply by 10
Normal HR
60-100 beats/min
Define bradycardia
<60 beats/min
Define tachycardia
> 100 beats/min
How to determine the regularity of a heart rhythm on an ECG?
Using calipers, measure the distance between a pair of R waves. Leave the calipers at that distance, and measure the next pair of R waves to determine whether the distance is the same.
What does it mean if the PR interval is longer than 0.20 seconds with a regular rhythm?
First- or second-degree heart block is present.
List some causes of bradycardia
- stimulation of vagus nerve (e.g., during tracheal suctioning)
- hypothermia
- increased intracranial pressure (ICP)
- may be normal in well-conditioned athletes
What is treatment of bradycardia?
If accompanied by shortness of breath, hypotension, or abnormal beats, atropine is used; a pacemaker may also be indicated.
List some causes of tachycardia
- Hypoxemia
- Increased sympathetic nervous system stimulation (e.g fear, anxiety)
- Medication
What is the treatment for tachycardia?
- Stop underlying cause
- Administration of digitalis or beta blockers
How would you identify a sinus arrhythmia on an ECG?
The distance between the R wave of the QRS complex varies and is inconsistent.
What is the treatment for sinus arrhythmia?
None is necessary. It is normal in young, healthy individuals
More than ____ premature atrial contractions (PACs) is considered a major arrhythmia.
6
List some causes of premature atrial contractions (PAC) - 5
- atrial irritability caused by organic heart disease
- central nervous system (CNS) disturbances
- sympathomimetic drugs
- tobacco
- caffeine
If more than 6 PACs are present, what can be used to treat the issue?
Lidocaine
More than ____ PVCs is considered major.
6
When every other beat is a PVC, the arrhythmia is termed what?
Bigeminy
When every third beat is a PVC, the arrhythmia is termed what?
Trigeminy
List some causes of PVCs.
- ventricular irritability caused by hypoxia
- acid-base disturbances
- electrolyte abnormalities
- an excessive dose of digitalis
- congestive heart failure (CHF)
- myocardial inflammation
- coronary artery disease
IDENTIFY WHAT HEART RHYTHM THIS IS
P waves have a characteristic sawtooth pattern and are often referred to as F waves.
Atrial flutter
What are treatment drugs for PVCs? (3)
- intravenous lidocaine
- procainamide
- propranolol if more than 6 PVCs per minute
List some causes of atrial fibrillation (4)
- Hypoxia
- Arteriosclerotic heart disease
- Mitral stenosis
- Valvular heart disease
How do you treat atrial fibrillation? (3)
- Cardioversion
- Propranolol
- Digitalis
How do you treat atrial flutter? (5)
- Cardioversion
- Carotid artery massage
- Procainamide
- Digitalis
- Tranquilizers
How do you treat v-tach?
- lidocaine
- defibrillation
- CPR
- procainamide
- amiodarone
How do you treat v-fib?
- defibrillation
- CPR
- If this arrhythmia is not reversed, death soon results because there is essentially no blood being pumped out of the heart.
How do you treat first-degree heart block?
- Atropine
- Isoproterenol
What is the cause of first-degree heart block?
Complication of digoxin or beta blockers, ischemia of the AV node
How do you treat second-degree heart block? (3)
- isoproterenol
- atropine
- pacemaker
How do treat third-degree heart block?
Pacemaker
What are causes of third-degree heart block?
- AV node damage
- Myocardial ischemia
Wave pattern abnormalities: the QRS complex is normal but may be preceded by two to four P waves.
Second-degree heart block
A condition in which there is dissociation between the electrical and mechanical activity of the heart.
Pulseless Electrical Activity (PEA)
The ECG pattern that appears on the ECG monitor does not reflect the actual mechanical activity of the heart.
The therapist must know whether the patient has a temporary pacemaker before beginning a treatment such as chest physical therapy (CPT), because this type of pacemaker can become dislodged with vigorous movement.
Okay!
A portable, battery-powered recording device that records the patient’s ECG tracing while the patient conducts daily activities. The monitoring is generally done over 24 hours.
Holter monitor
HEMODYNAMIC MONITORING
How is systemic arterial blood pressure most accurately measured?
By placing a catheter directly into a peripheral artery.
What are the most common peripheral artery sites?
- Radial
- Brachial
- Femoral
HEMODYNAMIC MONITORING
List some complications of arterial catheters
- Infection
- Hemorrhage
- Ischemia
- Thrombosis and embolization
HEMODYNAMIC MONITORING
A weak pulse distal to the puncture site may indicate __________________.
Thrombosis
Pulse pressure is usually about _ mm Hg.
40
________ represents the average pressure during the cardiac cycle.
Mean arterial pressure
MAP range
80-100 mm Hg
What does the dicrotic notch represent?
Closing of the aortic valve
The dicrotic notch may disappear when the systolic pressure drops below ____ mm Hg.
50 to 60
List the causes of a “damped” waveform
- Occulusion of the catheter tip by a clot
- Catheter tip resting against the wall of the vessel
- Clot in the transducer or stopcock
- Air bubbles in the line
HEMODYNAMIC MONITORING
How would you correct air bubbles in the line?
Disconnecting transducer and flushing out air bubbles.
HEMODYNAMIC MONITORING
How do you correct occlusion of the catheter tip by a clot?
Aspirating the clot and flushing with heparinized saline.
HEMODYNAMIC MONITORING
How do you correct catheter tip resting against the wall of the vessel?
Repositioning catheter while observing waveform.
HEMODYNAMIC MONITORING
How do you correct clot in transducer or stopcock?
Flushing system; if no improvement is seen in the waveform tracing, disconnect the transducer and change the stopcock.
HEMODYNAMIC MONITORING
What are some causes of an abnormally high or low pressure readings?
- Improper calibration: correct by recalibration of monitor and strain gauge.
- Improper transducer position: correct by ensuring the transducer is kept at the level of the patient’s heart.
If the transducer is placed below the level of the heart, what will this do to your pressure reading?
Pressure reading will read higher than it actual is. VICE VERSA.
No pressure reading; causes include:
(1) Improper scale selection: correct by selecting appropriate scale.
(2) Transducer not open to catheter: correct by checking system and making sure the transducer is open to the catheter.
Flow-Directed Pulmonary Artery Catheter (Swan-Ganz Catheter)
The pulmonary artery catheter is a balloon-tipped catheter made of polyvinyl chloride that is used to measure what?
- CVP
- PAP
- PCWP (PAWP)
Flow-Directed Pulmonary Artery Catheter (Swan-Ganz Catheter)
What is the distal lumen used for?
Measurement of PAP and for obtaining mixed venous blood from the pulmonary artery.
Flow-Directed Pulmonary Artery Catheter (Swan-Ganz Catheter)
What is the proximal lumen used for?
Measurement of CVP or right atrial pressure and for the injection of fluids to determine QT.
The catheter also allows for the aspiration of blood from the pulmonary artery for mixed venous blood gas sampling and injection of fluids to determine QT.
Something to know.
Insertion of the Pulmonary Artery Catheter
The catheter is inserted through the ____ vein. (5)
brachial, femoral, subclavian, or internal or external jugular
When obtaining PCWP, the balloon should not be inflated for no more than ______ seconds or pulmonary infarction will occur.
15-20 seconds
CENTRAL VENOUS PRESSURE
Central venous pressure (CVP) may be monitored
with a PAC or from a separate CVP catheter that is inserted through the subclavian, jugular, or brachial vein. The CVP catheter is connected to a water manometer, which reads the pressure in cm H2O. Measuring the CVP with a pulmonary artery catheter gives the pressure in mm Hg.
Which is more accurate?
PAC
Normal CVP values
3-8 cmH2O
2-6 mm Hg
Pulmonary artery pressure (PAP) is an important
measurement in the care of critically ill patients with _____.
sepsis, acute respiratory distress syndrome (ARDS), pulmonary edema, and MI.
Normal PAP systolic values
15-30 mm Hg
Normal diastolic PAP values
5-15 mm Hg
Normal mean PAP
10-20 mm Hg
Conditions that increase PAP
(1) Pulmonary hypertension (resulting from hypercapnia, acidemia, or hypoxemia, for example)
(2) Mitral valve stenosis
(3) Left ventricular failure
Conditions that decrease PAP
(1) Decreased pulmonary vascular resistance (pulmonary vasodilation); caused by improved oxygenation
(2) Decreased blood volume
Is PCWP a measurement of the right or left side of the heart?
Left
Normal PCWP values
5-10 mm Hg
A PCWP value of more than 18 mm Hg usually indicates what?
Impending pulmonary edema
PCWP is elevated in patients with cardiogenic pulmonary edema and is normal in patients with noncardiogenic pulmonary edema.
Know.
Complications of Pulmonary Artery Catheter
Insertion (7)
- Damage to tricuspid valve
- Damage to pulmonary valve
- Pulmonary infarction
- Pneumothorax
- Cardiac arrhythmias
- Air embolism
- Ruptured pulmonary artery
Normal QT values
4-8 L/min
QT may be measured through the pulmonary artery catheter with the use of the ________ technique.
A cold saline or dextrose solution is injected through the proximal port of the catheter. Heat loss occurs from the injection port to the distal tip of the catheter. The rate of blood flow determines the amount of heat loss and is measured on the QT computer.
Thermodilution technique
QT equation
VO2/CaO2 - CvO2 x 10
CaO2 Equation
CaO = 1.34 x Hb x SaO+ PaO2 x 0.003
The normal C(a 2 v)O2, or arteriovenous O2 content difference, is _______.
4 to 6 mL/dL
An arteriovenous O2 content difference of more than 6 mL/dL may be the result of what?
Decreased CO
An arteriovenous O2 content difference of less than 4 g/dL may be the result of what?
increased QT (less time for tissues to extract O2)
The portion of the QT that perfuses through the lungs without coming in contact with ventilated alveoli.
Intrapulmonary shunting
Normally, intrapulmonary shunting is about ________ of the QT and is primarily caused by anatomic shunting.
2-5%
Conditions that increased physiologic shunting
- Pneumonia
- Pneumothorax
- Pulmonary edema
- Atelectasis
A shunt less than ____ is normal.
10%
Shunt of more than ____% is a serious, life-threatening
condition that requires aggressive cardiopulmonary support.
30
Normal CI range
(cardiac index)
2.5 to 4.0 L/min/m2
The amount of blood ejected from the ventricle during ventricular contraction.
Stroke volume
A measurement of the resistance that the left ventricle must overcome to eject its volume of blood. This is known as afterload.
SVR
Normal SVR
11.25 to 17.5 mm Hg/L/min, or 900 to 1400 dyne 3 seconds 3 cm25.
A reflection of the afterload of the right ventricle.
Pulmonary Vascular Resistance
PVR Equation
MPAP-PCWP/QT
This resistance formula may be multiplied by 80 to convert to resistance units of dynes x seconds x cm-5.
Normal PVR
1.38 to 3.13 mm Hg/L/min, or 110 to 250 dyne x seconds x cm-5.
Normal O2 consumption (VO2)
150 to 275 mL/min
What may be calculated to help determine whether a patient has been overfed, which can promote excessive carbon dioxide production?
RQ - Respiratory quotient
Normal RQ - Respiratory quotient
0.80-0.85
Exercise Stress Testing
Before testing, perform a patient history and
physical examination. The examination should include:
a. Pulmonary function tests
b. Carbon monoxide diffusion capacity
c. Arterial blood gas (ABG) measurements
d. Blood pressure
e. Before and after bronchodilator study (if airflow obstruction exists)
f. Resting ECG
A physician should always be present during the stress test; always have the following emergency equipment available:
a. Defibrillator
b. O2 source
c. Manual resuscitator with mask
d. Oral airway
e. Laryngoscope and endotracheal tubes
f. IV setup with 5% dextrose
g. Cardiac medications
Increased CVP
- Hypervolemia
- Pulmonary hypertension
- Right venticular failure
- Pulmonary valve stenosis
- Triscupid valve stenosis
- Pulmonary emobolism
- Arterial vasodilation
- LHF
- Improper transducer placement
- Positive pressure ventilator breath
- Severe flail chest or pneumothorax
Decreased CVP
- Hypovalemia
- Vasodilation
- Leaks or air bubbles in the pressure line
- Improper trasnducer placement (above level of the RA)
