Test 2 Flashcards
The heart is a ______________-chambered muscular organ approximately the size of a fist.
Four
Where is the heart positioned?
Mid-mediastinum of the chest, behind the sternum.
Approximately ⅔ of the heart lies to the left of the midline of the sternum between which two ribs?
2nd and 6th ribs
The apex of the heart is formed by the tip of the left ventricle and lies above the diaphragm at the level of the ____________________.
5th intercostal space to the left.
The base of the heart is formed by the_________________.
Atria and projects to the right, lying below the 2nd rib.
Posteriorly, where does the heart rest?
Level of the 5th to the 8th thoracic vertebrae.
Externally, surface grooves called _________________ mark the boundaries of the heart chambers.
Sulci
The heart is enclosed in a sac called the _________________.
Pericardium
A thin layer of fluid called the _____________________ separates the two layers of the serous pericardium.
Pericardial fluid
Tough, loose-fitting outer layer and inelastic sac surrounding the heart.
Fibrous pericardium
Serous pericardium consists of what two layers?
- Visceral layer
- Parietal layer
Which layer of serous pericardium is the inner lining of the fibrous pericardium?
Parietal layer
Which layer of the pericardium covers the outer surface of the heart and great vessels?
Visceral layer
Inflammation of the pericardium.
Pericarditis
An abnormal amount of fluid can accumulate between the layers of the pericardium resulting in a ________________________.
Pericardial effusion
What is a cardiac tamponade?
When excess pericardial fluid compresses the heart muscle, leading to a serious decrease in blood flow to the body. This, ultimately, may lead to shock and death.
Cardiac tamponade ultimately may lead to _____________________.
- Shock
- Death
The heart wall consist of three layers. What are they?
- Outer epicardium
- Middle myocardium
- Inner endocardium
A cardiac tamponade should be suspected in patients presenting with: (8)
Beck’s Triad
- Muffled heart sounds
- Hypotension
- Jugular venous distention
- Pulsus paradoxus
- Tachycardia
- Tachypnea
- Narrowing pulse pressure
- Severe dyspnea
Which layer of the heart composes the bulk of the heart muscle?
Myocardium
The heart consists of how many valves and chambers?
8!!!
Each AV ring is composed of dense connective tissue termed annulus fibrosus cordis which encircles the bases of the pulmonary trunk, aorta, and heart valves and electrically isolates the aorta from ______________.
The ventricles
____________ are two thin-walled “cups” of myocardial tissue that contribute little to the total pumping activity of the heart.
Atrial chambers
The vascular system has two major subdivisions: What are they?
- Systemic circulation
- Pulmonary circulation
What’s the other name for epicardium?
Visceral layer
What does CPR mimic?
Cardiac output
Which type of pericardium consists of two layers?
Serous pericardium
Can electrical impulses be transmitted through the heart muscle and connective tissue from the atria to the ventricles?
No.
What is regurgitation?
Back flow of blood through a malfunctioning leaky valve.
The two atrial chambers are separated by ________________________.
An interatrial wall or septum.
On the right side of the interatrial septum is an oval depression called the ______________.
Fossa ovalis cordis
Two lower chambers of the heart make up the bulk of the heart’s muscle mass and does most of the pumping that circulates the blood.
Ventricles
The right and left ventricles are separated by a muscle wall called _________________________.
Interventricular septum
The AV valves close during systole, what does this prevent?
Back flow of blood into the atria.
The free ends of the AV valves are anchored to papillary muscles of the endocardium by the _____________________.
Chordae tendineae cordis
During systole, _________________ prevents the AV valves from swinging upward into the atria.
Papillary muscle
Damage to the either the chordae tendineae cordis or the papillary muscles can impair the function of the __________.
AV valves and cause leakage upward into the atria.
What is stenosis?
Pathologic narrowing or constriction of a valve outlet.
What happens with mitral stenosis?
High pressure in the left atrium back up into the pulmonary circulation. Those high pressures can cause:
-Pulmonary edema
-Diastolic murmur
_________________ prevent backflow of blood into the ventricles during systole
Semilunar valves
Two main coronary arteries, one in the right and one in the left, arise from the ___________________________.
Root of the aorta right underneath the semilunar valves.
When does blood flow through the coronary arteries?
Only during diastole when the semilunar valves are closed.
Partial obstruction of a coronary artery can lead to _______________________.
Tissue ischemia (decreased oxygen supply)
Complete obstruction of a coronary artery may cause _______________________.
- Tissue death
- Myocardial infarction
________________________ is the name given to three types of CAD.
Acute Coronary Syndrome
What are the 3 names of the acute artery disease types?
- Unstable angina or angina pectoris
- Non-ST segment elevation myocardial infarction (NSTEMI)
- ST segment elevation myocardial infarction (STEMI)
What condition remains responsible for approximately one-third of all deaths in people over age 35?
Heart disease
What are classic signs of tissue ischemia?
- Chest pain
- SOB
Resulting in a clinical condition called angina pectoris.
What are classic signs of an MI? (5)
- Pain or tightness in the chest, back, arms, neck.
- Fatigue
- Lightheadedness
- Abnormal heart beat
- Anxiety
Nearly how many middle aged men and women in the USA will develop a CHD?
Men: 1/2
Women: 1/3
Coronary veins gather together into large vessel called the ___________________.
Coronary sinus
The coronary sinus empties into the ___________________.
Right atrium
Where does the thebesian veins empty?
Into all of the heart chambers.
Any deoxygenated blood coming from the thebesian veins that enters the left atrium or ventricle lowers the overall oxygen content of the _______________.
Systemic circulation
Because the thebesian veins bypass or shunt around the pulmonary circulation as part of the normal anatomy, this phenomenon is called an ______________.
Anatomic shunt
Normal anatomic shunts account for approximately ______% of total cardiac output.
2-3%
The performance of the heart as a pump depends on its ability to:
- Initiate and conduct electrical impulses
- Synchronously contract the heart’s muscle quickly and efficiently
The ability of cells to respond to electrical, chemical or mechanical stimulation.
Excitability
What can increase myocardial excitability? (3)
- Electrolyte imbalances
- Congenital cardiac anomalies
- Certain drugs
Can lead to cardiac arrhythmias
The unique ability of the cardiac muscle to initiate a spontaneous electrical impulse (depolarization and repolarization).
Inherent rhythmicity or automaticity
What are the heart’s primary pacemakers?
- SA node
- AV node
An electrical impulse from any source other than a normal heart pacemaker is considered what?
Abnormal or ectopic heartbeat
The ability of the myocardial tissue to spread and conduct electrical impulses.
Conductivity
Abnormal conductivity can affect ______________________.
Timing of the chamber contractions and decrease cardiac efficiency.
_________________, in response to an electrical impulse, is the primary function of the myocardium.
Contractility
The period during which the myocardium cannot be stimulated is called ____________________.
The refractory period.
It lasts approximately 250 ms, nearly as long as the heart contraction or systole.
Individual cardiac fibers are enclosed in a membrane called the _________________.
Sarcolemma
Cardiac fibers are separated by irregular transverse thickenings of the sarcolemma called ___________________.
Intercalated discs
Explain Starling’s law of the heart, also known as Frank-Starling law.
The more a cardiac fiber is stretched, the greater the tension it generates when contracted.
Where does the systemic circulation begin and end?
Begins: Aorta on the left ventricle
Ends: Right atrium
Where does the pulmonary circulation begin and end?
Begins: Pulmonary artery out of the right ventricle
Ends: Left atrium
Venous or deoxygenated blood from the head and upper extremities enters the right atrium from the _______.
SVC
Venous blood from the abdomen and lower body enters from the ______.
IVC
_____________________ are the only arteries in the blood that carry deoxygenated or venous blood.
Pulmonary arteries
The systemic circulation has three major components. What are they?
- Arterial sytem
- Venous system
- Capillary system
This system consists of large, highly elastic, low-resistance arteries and small, muscular arterioles or vary resistance.
Arterial system
What is referred as conductance vessels?
Large arteries
What is referred as resistance vessels?
Small arterioles
What plays a major role in the distribution and regulation of blood pressure?
Arterioles
________ controls blood flow into the capillaries.
Arterioles
_________________ are commonly referred as exchange vessels.
Capillaries
This system maintains a constant exchange of nutrients and waste products for cells and tissues of the body.
Capillary system
Cardiac Output equation
CO= HR x SV
P wave represents ___________________.
Atrial depolarization
T wave represents ___________.
Ventricular repolarization
The left atrium pumps blood into the left ventricle and the blood is then pumped to the body through the _____.
AORTA!
Blood flows into the network by an _________ and out through a ________. Direct communication between these vessels is called _______.
Blood flows into the network by an arteriole and out through a venule.
Direct communication between these vessels is called arteriovenous anastomosis.
Capillaries have smooth muscle rings at their proximal ends called ____.
Precapillary sphincters
What happens when precapillary sphincters contract and relax?
- Contraction: decreases blood flow locally
- Relaxation: Increases local perfusion
_________ and ___________ allow precise control over the direction and amount of blood flow to a given organ or area of tissue.
Sphincters and bypasses
This system consist of small, expandable venules and veins and larger, more elastic veins.
Venous system
At any given time, the veins and venules hold approximately __________ of the body’s total blood volume.
2/3
The components of the venous system, especially the small, expandable venules and veins are termed _____.
Capacitance vessels
What must the venous system overcome to return blood to the heart?
Gravity
What four mechanisms aid the venous return to the heart?
- Sympathetic venous tone
- Skeletal muscle pumping or “milking”
- Cardiac suction
4. Thoracic pressure differences caused by respiratory efforts; often called the thoracic pump
Why is thoracic pressure differences caused by respiratory efforts; often called the thoracic pump so important to RTs?
Artificial ventilation with positive pressure reverses normal thoracic pressure gradients.
Does PPV assists with venous return?
No, it impedes it.
What type of patients are vulnerable to a reduction in CO when PPV is applied to the lungs?
Hypovalemic or in cardiac failure
The right side of the heart generates a systolic pressure of ___________ to drive blood through the low-resistance, low-pressure pulmonary circulation.
25 mm Hg
The left side of the heart generates systolic pressures of _________ to propel blood through the high pressure, high-resistance systemic circulation.
120 mm Hg
Blood flow through the vascular system is opposed by what?
Frictional forces
The sum of all frictional forces opposing blood flow through the systemic circulation is called ___________.
SVR - Systemic Vascular Resistance
The beginning pressure of the systemic circulation is the ________.
Mean Aortic Pressure
The ending pressure of the systemic circulation is the ________.
Right atrial pressure or CVP
Resistance to blood flow in the pulmonary circulation is approximately _______ of that of the systemic circulation.
One-tenth
Is pulmonary circulation characterized as a low-pressure, low resistance or high-pressure, high resistance system?
Low-pressure, low resistance system
Is systemic circulation characterized as a low-pressure, low resistance or high-pressure, high resistance system?
High-pressure, high resistance system
What is the priority of the cardiovascular system?
Maintain perfusion pressures to tissues and organs at functional levels, even under changing conditions.
MAP is directly related to the ______________ and inversely related to _______________.
MAP is directly related to the volume of blood in the vascular system and inversely related to its capacity.
MAP = Volume/Capacity
MAP (Mean Arterial Pressure) Equation
MAP = CO x SVR
In a normal adult, MAP ranges from ____.
80-100 mm Hg
MAP is regulated by changing what?
Either changing the volume of circulating blood, the capacity of the vascular system or both
Does vasoconstriction cause BP to increase or decrease?
Increase
Does vasodilation cause BP to increase or decrease?
Decrease
Vascular space decreases when ____ occurs.
Vasoconstriction
Vascular space increases when ____ occurs.
Vasodilation
Define vasoconstriction.
Constriction of the smooth muscles in the peripheral blood vessels.
Define vasodilation.
Constriction of the smooth muscles in the arterioles.
What happens when MAP decreases below 60 mm Hg?
Perfusion to the brain and kidney are severely compromised and organ failure may occur in minutes.
The MAP is one of the first variables that is monitored in __________.
Septic patients
Define prolonged hypotension.
MAP of less than 60-65 mm Hg.
What is the cardiovascular system responsible for?
Transporting metabolites to and from the tissues under various conditions and demands.
Stroke Volume Equation.
SV = EDV-ESV
EDV ranges for normal persons.
110-120 mL
What is ECGs primarily used for?
To help evaluate a patient with signs/symptoms of cardiac disease.
What are some reasons why the Dr. would order an ECG? (6)
Patients complaining of:
- Chest pain
- SOB
- Dyspnea with palpations
- Weakness
- Lethargy
- Syncope
What is this called?
Stimulation of the polarized cells cause an influx of Na+ into the interior portion of the cell.
Depolarization
Depolarization causes the cardiac muscle cells to _____.
Contract
Which part of the body is most sensitive to changes in the local metabolite levels?
Brain
The total amount of blood pumped by the heart per minute.
Cardiac output
SV is affected primarily by intrinsic control of what three factors?
- Preload
- Afterload
- Contractility
The heart does not eject all of the blood it contains during systole. Instead, a volume called the ____, remains inside the ventricles.
End-systolic volume
EF equation
EF = SV/EDV x 100
An increase in SV occurs when either…
- EDV increases
- ESV decreases
A decrease in SV occurs when either…
- EDV decreases
- ESV increases
_______ in preload (EDV) and _____ in ESV result in increased SV in the healthy heart.
Increases in preload (EDV) and decreases in ESV result in increased SV in the healthy heart.
____ in afterload can decrease SV, especially in the failing heart by increasing the ESV.
Increases in afterload can decrease SV, especially in the failing heart by increasing the ESV.
Drugs that increase contractility of the heart muscle are called __.
Positive inotropes
Drugs that decrease contractility of the heart muscle are called __.
Negative inotropes
___ and ____ impair myocardial function and decrease cardiac contractility and CO.
- Profound hypoxia
- Acidosis
The impulse-conducting system cells have the ability to stimulate the heart without ______.
Influence of the nervous system
A rapid return of the cell to the “polarized” position.
Repolarization
The impulse-conducting system has three type of cardiac cells capable of electrical excitation:
- Pacemaker cells (SA and AV node)
- Specialized rapidly conducting tissues (Purkinje fibers)
- Atrial and ventricular muscle cells
The ability of cardiac cells to depolarize without stimulation.
Automaticity
The impulse-conducting system is responsible for what?
Initiating the heartbeat and controlling the heart rate. Also coordinates the contraction of the heart chambers.
Where is the SA node located?
In the upper portion of the right atrium.
______ has the greatest degree of automaticity and paces the heart.
SA node
A defect in the impulse-conducting system may lead to:
- Inadequate CO
- Decreased tissue perfusion
Define ectopic beat.
Any heartbeat originating outside of the SA node.
The SA node is innervated by the ___.
Autonomic nervous system
- Sympathetic and parasympathetic nervous system influence HR.
The electrical impulse generated by the SA node travels across the right atrium through intraatrial pathways, to left atrium by the way of ___.
Bachmann bundle
____ is the backup pacemaker of the heart.
AV node
AV node paces ventricular activity at what rate?
40-60 beats/min
Where is the AV node located?
Intraventricular septum
Why is the eletrical impulse temporarily delayed at the AV node?
To allow the ventricles time to fill with blood.
Normally the QRS complex is shorter than _____.
0.12 second
In the first degree heart block, the PR interval is longer than _____.
0.12 second
Type II heart block is seen as a series of _________.
Nonconducted P waves followed by a P wave that is conducted to the ventricles.
Treatment is usually not needed for first-degree heart block if the patient is able to ____.
Maintain adequate BP
Ventricular tachycardia is a run of _________________.
3 or more PVCs.
When atrial muscles quivers in an irregular pattern that does not result in a coordinated contraction.
Atrial fibrillation
Where is V1 placed?
4th intercostal space to the right of the sternum.
Where is V6 placed?
5th intercostal space at the midaxillary line
The wave of depolarization in the atria is seen as the _____ on an ECG.
P wave
What’s the size of the P wave?
- 2.5 mm high
- 3 mm long
What may cause the P wave to enlarge to a larger height and length?
Atrial hypertrophy
Why is atrial repolarization not seen on an ECG?
It’s obscured by the electrical activity occurring in the ventricles at the same time.
Ventricular depolarization is seen as the ____ on an ECG.
QRS complex
Why is the QRS complex much larger than the P wave?
Muscle mass of the ventricles is greater than the atria.
QRS complex
The first wave of the complex is negative (downward), it’s labeled the _____.
Q wave
QRS complex
The initial positive (upward) deflection is referred as the ____.
R wave
QRS complex
The next negative deflection after the R wave is labeled the ___.
S wave
What wave represents ventricular repolarization?
T wave
Typical PR interval is ________ long.
0.12 to 0.20 seconds
_____ refers to the distance (time) between the start of atrial depolarization and the start of ventricular depolarization.
PR interval
What does a PR interval longer than 0.20 seconds represents?
The impulse is abnormally delayed at the AV node and a “block” is present.
_____ represents the times from the end of ventricular depolarization to the start of ventricular repolarization.
ST segment
Cells that conduct the electrical impulse throughout the heart.
Conducting cells
Cells that contract in response to electrical stimuli and pump blood
Myocardial cells
Specialized cells that have a high degree of automaticity and provide electrical power for the heart
Pacemaker cells
What does an inverted T wave suggest?
Ischemia of the heart muscle
Abnormal configuration of the T wave occurs with _____.
Electrolyte abnormalities such as hyperkalemia (where the T wave take a “peaked” or sharper than normal appearance)
What is the most life-threatening arrhythmia?
Ventricular fibrillation
Treatment for V-fib (4)
- Rapid defibrillation
- CPR
- Administration of O2 and anti antiarrhythmic medications
Immediate reversal of underlying cause
Erratic quivering of the ventricular muscle mass that cause CO to drop to zero
Ventricular fibrillation
Glossy irregular fluctuations with a zigzag pattern describes what ECG pattern?
Ventricular fibrillation
Serious condition that is characterized by a disassociation between the electrical and mechanical activity of the heart.
Pulseless Electrical Activity
What is one of the hallmarks of VT in general?
Third-degree AV block because ventricles are beating independently of the atria
VT is considered “sustained” if it lasts longer than _____.
30 seconds
What are some conditions that can produce atrial flutter? (6)
- Rheumatic heart disease
- Coronary heart disease
- Pulmonary embolism
- Stress
- Renal failure
- Hypoxemia
_____ is an ECG characterized by a saw-tooth baseline pattern.
Atrial flutter
The standard ECG is calibrated so that ______ causes an upward deflection of 10 small boxes or 2 large large boxes on the vertical axis.
1 mV
What is the size of the large ECG boxes?
5x5 mm
What is the size of the small ECG boxes?
1x1 mm
Each large box represents ____ second.
0.20 second
Each small box represents ____ second.
0.04 second
A negative QRS complex in lead I is consistent with right-axis deviation, which is often caused by ____.
Cor pulmonale
The six chest or precordial leads are called ______.
- V1
- V2
- V3
- V4
- V5
- V6
What represents the time in which the impulse begins in the SA node and travels across the atria to the AV node, where it is briefly held before passing on to the ventricles?
PR interval
_______ is isoelectric and seen as a flat line that is not above or below the neutral baseline.
ST segment
An elevated or depressed ST segment is common with _____.
- Cardiac ischemia
- MI
Speficially, a depressed ST segment is a common finding with _______.
Cardiac ischemia such as occurs in angina
Speficially, a elevated ST segment is a common finding with _______.
Certain types of MIs
The PR is normal if its not longer than how many boxes?
1 large box (0.2 seconds)
How to measure PR interval.
Start of P wave and start of QRS complex.
The ST segment should be flat and at least no more than ________ above or below the baseline.
1 mm
_________ is identified to asses the regularity of the rhythm.
R-R rhythm
If the variation between the R-R intervals exceeds 0.12 second , abnormal conduction called a “__________________” exists.
Bundle branch block.
Treatment for sinus tachyacardia.
Eliminate the underlying cause, such as pain relievers, fever reducers, fluids or oxygen
Some causes of sinus tach.
- Anxiety
- Pain
- Fever
- Hypovolemia
- Hypoxemia
Sinus brady is most often caused by: (3)
-Hypothermia
- Abnormalities in SA node
- Intense athletic conditioning
Medication to treat sinus brady:
Atropine
Sinus arrhythmia is common and recognized by the _____.
Irregular spacing between QRS complexes
Treatment:
Most sinus arrhythmias are ____.
Benign and don’t need treatment.
First degree heart block is common after an _____ .
MI that damages AV node or may be a complication of certain medications like digoxin and beta blockers.
First degree heart block indicates _____.
The impulse from the SA node is getting through the ventricles but is delayed in passing through the AV node of bundle of His.
Other names for Type 1 Second-Degree Heart Block
- Wenckebach
- Morbitz type I
Treatment for type I second-degree heart block
Not needed bc it usually doesn’t impair CO or cause symptoms
Treatment for type II second-degree heart block
Atropine until pacemaker can be inserted
_________ heart block is the most serious of the different types of heart blocks.
Third-degree
Third-degree heart block indicates _________.
The conduction system between the atria and ventricles are completed blocked and impulse conducted in the SA node are not conducted to the ventricles.
No relationship between the P wave and QRS complex.
P-P intervals an R-R intervals are regular but they have no correlation with one another.
Third-degree heart block
Third-degree heart block is often caused by
MI or drug toxicity
Treatment for Third-degree heart block. (3)
Addressing the underlying cause (MI) and medication to speed up the ventricles and temporary external pacemaker until a permanent one can be placed.
Limb leads are called ___ .
- I
- II
- III
- aVr
- aVL
- aVf
Third-degree heart block
The QRS complexes are normal in configuration if the ventricles are paced by the AV node. What happens if they are paced by an abnormal site in the myocardium?
QRS complex may be abnormally wide, consistent with a bundle branch block
Atrial flutter is the rapid depolarization of the atria resulting from an ectopic focus that depolarizes at a rate of _________.
250-350 bpm
What is the HR for ventricular tachycardia?
100-250 bpm
Name a medication that may cause sinus arrhythmia
Digoxin
Mobitz type II heart block requires treatment in most cases because the reduction in ventricular rate causes ____.
Decrease in blood pressure
What medication may help with a Mobitz type II heart block?
Atropine
With third-degree heart block, most commonly, the atria are paced by the SA and the ventricles are paced by the _____.
AV node
What are the causes of pulseless electrical activity?
7 H’s
- Hypovalemia
- Hypoxia
- Hyperkalemia
- Hypokalemia
- Hypothermia
- Hypoglycemia
- Hydrogen ion (acidosis)
6 Ts
- Trauma (most common)
- Tension pneumothorax
- Toxins
- Tamponade (cardiac)
- Thrombosis (coronary)
- Thrombosis (pulmonary)
What is the drug of choice for sinus bradycardia?
Atropine
What is the drug of choice to correct PVCs?
Lidocaine
Systemic venous blood returns to the right atrium via __________.
SVC/IVC
Blood flow through the Heart
- SVC/IVC
- Right atrium
- Tricuspid valve
- Right ventricle
- Pulmonary semilunar valve
- Pulmonary arteries
- Lungs
- Pulmonary veins
- Left atrium
- Biscuspid/Mitral valve
- Left ventricle
- Aortic valve
- Aorta
- Body
Going from left to right, the ___ wave begins the ECG.
P wave (atrial depolarization)
Blood flows through the coronary arteries only during ______.
Diastole when the semilunar valves are closed.
The pressure gradient between the left and right side of the heart helps ___.
The suction effect in returning venous blood to the right side of the heart.
The beginning pressure of the pulmonary circulation is the ________.
Mean PA pressure
The ending pressure of the pulmonary circulation is the ________.
Left Atrial Pressure
The results of SEPSISPAM study suggest that a MAP target of ________ is usually sufficient in patients with septic shock, but a higher MAP, around _______ may be preferable in patients with chronic arterial hypertension.
The results of SEPSISPAM study suggest that a MAP target of 65-75 is usually sufficient in patients with septic shock, but a higher MAP, around 75-85 may be preferable in patients with chronic arterial hypertension.
During the resting phase or diastole, the ventricles fill to a volume called ______.
End- diastolic volume
If the EDV remains constant while the ESV increases, the SV _____.
Decreases
Factors that increase HR are called ____.
Positive chronotropic factors
Factors that decrease HR are called ____.
Negative chronotropic factors
When the pumping efficiency of the heart is so low that CO is inadequate to meet tissue needs, the heart is said to be in ___.
CHF
What is this?
Normal Sinus Rhythm
What is this?
Sinus Tachycardia
Common causes:
- Fever
- Pain
- Anxiety
- Hypoxemia
- Hypovalemia
What is this?
Sinus Bradycardia
Common causes:
- Hypothermia
- Abnormalities in the SA node
- Intense athletic conditioning
What is this?
Sinus Arrhythmia
Common causes:
- May occur with the effects of breathing on the heart or as side effect to medications like digoxin
What is this?
Second-degree Heart Block type II
Common causes:
Most often the result of serious problems such as MI or ischemia
What is this?
First-degree heart block
Common causes:
Following an MI that damages the AV node or a complication of certain meds like digoxin or beta blockers
What is this?
Third-degree heart block
Common causes:
Often caused by MI or drug toxicity and it may render the heart unable to meet the normal metabolic demands of the body.
What is this?
Atrial Flutter
Common causes:
- Rheumatic heart disease
- Coronary heart disease
- Pulmonary embolism
- Stress
- Renal failure
- Hypoxemia
- Hypertension
What is this?
Atrial Fibrillation
Common causes:
Similar to atrial flutter
What is this?
PVCs
Common causes:
- Stress
- Caffeine intake
- Nicotine use
- Electrolyte imbalance
What is this?
Ventricular fibrillation
Common causes:
Similar to VT
What is this?
Ventricular tachycardia
Common causes:
- MI
- CAD
- Hypertensive heart disease
- Untreated OSA
Which one is less work?
a. Pressure triggering
b. Flow triggering
b. Flow triggering
The mechanism the ventilator uses to begin inspiration is the ____.
Triggering mechanism
The ventilator can initiate a set breath after a set time (time triggering), or the patient can trigger the machine (patient triggering) based on ______.
Pressure, flow or volume changes
What are the most common triggering variables?
Pressure and flow
What does the trigger variable do?
Begins inspiration
What does the limit variable?
Limits the pressure, volume, flow or time during inspiration but does not end the breath
What does the cycle variable do?
Ends the inspiratory phase and begins exhalation
The baseline variable is the _______ before a breath is triggered.
End-expiratory baseline (usually pressure)
The number of mandatory breaths delivered by the ventilator is based on what?
The length of the TCT.
When does a patient-triggered breath occur?
When the ventilator detects changes in pressure, flow or volume.
What are the two most common patient triggering mechanisms?
Pressure and flow
This setting determines the pressure or flow change required to trigger the ventilator.
Patient-effort control
The sensitivity level for pressure triggering usually is set at ____.
About -1 cmH2O
_________ occurs when the ventilator detects a drop in flow through the patient circuit during exhalation.
Flow triggering
Describe pressure limiting.
Allows pressure to rise to a certain level but not exceed it.
Describe volume triggering.
Volume triggering occurs when the ventilator detects a small drop in volume in the patient circuit during exhalation.
Inspiration is timed from when to when?
Beginning of the inspiratory flow to the beginning of the expiratory flow.
Describe limit variable.
The maximum value that a variable can attain (pressure, flow, volume or time).
Does reaching a set limit variable end inspiration?
NO!
Infant ventilators often _________ the inspiratory phase, but _________ inspiration.
Infant ventilators often pressure limit the inspiratory phase, but time cycle inspiration.
A breath is considered _________ if the inspiratory phase end when a predetermined time has elapsed.
Time cycled
Can ventilators use more than one limiting feature at a time?
Yes.
When gas flow from the ventilator to the patient reaches but does not exceed a maximum value before the end of inspiration, the ventilator is ____.
Flow limited
Maximum safety pressure is typically by the operator to a value of _______.
10 cmH2O above the average peak inspiratory pressure.
Ventilator manufacturers usually set internal maximum safety pressure at ______.
120 cmH2O
The variable that a ventilator uses to end inspiration is called ___.
Cycling mechanism
Can more than one cycling variable be used at a given time by the ventilator to end inspiration?
NO. Only one of four can be used
The ventilator measures the cycle variable during _______ and uses this information to govern when the ventilator will end gas flow.
Inspiration
When the inspiratory phase is terminated when set a set volume has been delivered.
Volume-cycled
When is plateau pressure measured?
End-inspiration
Inspiration ends when a set pressure threshold is reached at the mouth or upper airway.
Pressure-cycled
What is the most common cycling mechanism in the pressure support mode?
Flow
What can it mean if the volume of gas delivered to the patient may be less than the set volume?
May be a leak in the system
What is an advantage of pressure cycled ventilators?
They limit peak airway pressures
What are some disadvantages of pressure cycled ventilators?
- They deliver variable and generally lower tidal volumes when reductions in compliances and increases in resistance occurs
Inflation hold is designed to _____.
Maintain air in the lungs at the end of inspiration, before the exhalation valve opens.
What does the inflation hold do the I-time and E-time?
- Increases inspiratory time
- Reduces expiratory time
The expiratory phase encompasses the period from the _________.
The expiratory phase encompasses the period from the end of inspiration to the beginning of the next breath.
The baseline variable is the parameter that generally is controlled during _____.
Exhalation
If an adequate amount of time is not provided for exhalation what can occur?
Airtrapping, hyperinflation, leading to auto-PEEP or intrinsic PEEP.
When the ventilator cycles into the expiratory phase once the flow has decreased to a predetermined value during inspiration.
Flow cycling ventilation
Volume, pressure and time vary according to changes in lung characteristics
The inspiratory pause is occasionally used to _______.
Increase peripheral distribution of gas and improve oxygenation.
What is the most practical choice to use as a baseline variable?
Pressure
Define baseline pressure.
The pressure level from which a ventilator breath begins.
Plateau pressure is used to calculate _______.
Static compliance
Baseline pressure can be zero (atmospheric) which is called _____.
Zero-end expiratory pressure
Baseline pressure can be positive (above zero) which is called _____.
Positive end-expiratory pressure
Define capnography.
The measurement of carbon dioxide concentrations in respired gas.
_____________ involves the display of exhaled CO2 numerically without a waveform.
Capnometry
_________ describes the continuous display of CO2 concentrations as a graphic waveform called a capnogram
Capnography
Capnography/Capnometry Indications (8)
- Monitoring severity of pulmonary disease and evaluating response to therapy
- Use as an adjunct to verify tracheal rather than esophageal intubation has taken place.
- Graphic evaluation of the integrity of the patient-ventilatory interface
- Monitoring the adequacy of pulmonary and coronary blood flow
- Screening patients for pulmonary embolism
- Detection of CO2 rebreathing and the waning effects of neuromuscular blockade
- Monitoring CO2 elimination
- Optimization of mechanical ventilation.
Expiratory hold, or end-expiratory pause, is a maneuver transiently performed at ___________.
End-exhalation
An accurate reading of end-expiratory pressure is impossible to obtain if ________.
Patient is breathing spontaneously
What is the purpose of an expiratory hold?
Measure pressure associated with air trapped in the lungs at the end of expiration.
What does the expiratory retard maneuver mimic?
Pursed-lip breathing, by adding a degree of resistance during exhalation.
An elevated plateau pressure indicates a high probability of ___.
ARDS
What are some treatment options for atrial flutter? (4)
- Digoxin
- Beta blockers
- Calcium channel blockers
Occasionally, electrical cardioversion is required.
What are some treatment options for atrial fibrillation?
- Anticoagulant medications
- Beta blockers
- Calcium channel blockers
- Anti-arrthymia medications
Patients who dont respond to drug therapy: synchronized cardioversion or ablation
What are some treatment options for PEA?
- Emergency life support
- Immediate reversal of underlying cause
What determines how fast the inspired gas will be delivered to the patient?
Flow setting
Which ramp provides a progressive increase in flow?
Ascending ramp
Constant flow patterns are also called ___.
Rectangular or square waveforms
What does higher flows do to the I-time?
Shortens it and may result in higher peak pressures and poor gas distribution
Explain what slower flows can do for I-time.
May reduce peak pressures, improve gas distribution and increase airway pressure at the expense of increase I-time.
Shorter expiratory times can lead to _____.
Air trapping and using a longer I-time may also cause cardiovascular effects.
Flow is usually set to deliver inspiration in about ____.
1 second (Range: 0.8-1.2 seconds)
An I/E ratio of 1:2 or less is typically recommended. This can be achieved with initial peak flow setting of about ______.
60 L/min (range: 40-80 L/min)
A long I-time (requiring 3-4 time constants) has been shown to improve ventilation in nonhomogenous lungs such a those seen in ____.
ARDS
Are fast or slow flows better for patients with increased resistance such as COPD?
Fast flows!
Robin and colleagues reported that using flow rates up to _____ can improve gas exchange in patients with COPD by providing a longer E-time.
100 L/min
It is important to recognize that flows that are too high can result in _____.
Uneven distribution of inspired air in the lung and also cause persistent tachypnea in addition to increased PIP.
What are the most common flow patterns used clinically?
- Constant flow waveforms
- Descending waveforms
Which waveform provides the shortest I-time of all available flow patterns?
Constant flow rate
Descending ramp is used with what vent mode?
Pressure control
With a descending pattern, flow is the greatest at ______________.
Beginning of inspiration, when patient flow demand is the highest.
This pattern produces a tapered flow at the end of inspiratory phase.
Sine flow pattern
It is important to remember that in situations where Pplat is critical, _____________ can reduce peak pressures and increase Paw.
Descending ramp
When initiating MV, most clinicians will chose to start with a descending ramp or constant waveform for what reasons? (4)
- Mean airway pressure is higher with descending flow waveforms
- PIP is higher with ascending flow waveforms.
- Descending waveforms improve gas distribution
- Descending waveforms improve arterial oxygenation.
What flow pattern may be useful for patients with hypoxemia and low lung compliance?
Descending flow pattern, by maintaining low peak pressure and high Paw and improving gas distribution.
______________ produces a lower Paw compared with a descending flow pattern and may be useful in ventilation with patients with severe hypotension and cardiac instability.
Constant flow pattern
What flow pattern would be best for patients with increased airway resistance?
Descending pattern
It is important to know that ventilator circuits, expiratory valves and bacterial filters placed on the expiratory side of the patient circuit can produce a certain amount of expiratory retard because ____.
They cause resistance to flow
What is this and how would you fix it?
Overdistention of the lungs.
Decrease pressure or volume based on the mode
What is this waveform called?
Flow - Sinusoidal
What is this waveform called?
Flow - Exponential (decay)
What is this waveform called?
Flow and volume- Ascending ramp
What is this waveform called?
Flow - Descending ramp
What is this waveform called?
Flow and pressure - Rectangular, square, constant waveform
What is this waveform called?
Pressure - Exponential rise
What is this waveform called?
Volume - sinusoidal
What does this indicate?
Air leak
What does this indicate?
Presence of auto-PEEP
What does this indicate?
Note the diminished peak expiratory flow and the scooped-out concave shape of the expiratory F-V curve.
COPD
Chemical devices that rely on disposable colorimetric detector provide ________ estimates of exhaled CO2.
Qualitative
Spectroscopic devices provide _______ data on the concentration of expired CO2.
Quantitative
_______ are handheld devices composed of specially treated filter paper in a plastic casing that can be attached to a patient’s ET tube.
Chemical (colorimetric) capnometers
In some cases,ET placement in the trachea rather than the stomach may be difficult to determine because patient’s gastric CO2 may be elevated due to:
- Receiving mouth-to-mouth breathing
- Having recently ingested a carbonated drink and the presence of antacids
IR spectroscopy is based on the principle that ________.
Molecules containing more than one element absorb IR light in a characteristically manner.
CO2 absorbs IR radiation maximally at ____.
4.6 µm
Which type of sampling is attached directly to the ET tube?
Mainstream sampling
In __________ sampling devices, gas from the airway is extracted through a narrow plastic tube to the measuring chamber.
Sidestream sampling devices
The PetCO2 is dependent on ____.
Alveolar PCO2.
Influenced by CO2 production and effectiveness of ventilation
The production of CO2 is primarily determined by ____.
Metabolic rate
What are some things that can increase metabolic rate and VO2?
- Fever
- Sepsis
- Hyperthyroidism
- Seizures
What are some things that can decrease metabolic rate and VO2?
- Hypothermia
- Sedation
- Starvation
The PetCO2 is normally ________ lower than the PaCO2.
about 4-6 mm Hg
Failure of the capnogram to return to baseline indicates ______.
Rebreathing of exhaled gas
_______ devices increase the amount of deadspace added to the ventilator circuit.
Mainstream devices
During capnography, what should be recorded?
Ventilatory variables:
VT, RR, PEEP, I/E, PIP, FiO2
Hemdynamic variables:
Systemic and pulmonary pressures, CO, shunt, V/Q imbalances
__________ may lead to a false-negative capnography result.
Low CO
Gastric PCO2 is usually equal to ___.
Room air
______ is associated with low PetCO 2 and should not be confused with esophageal intubation.
Low perfusions of the lungs
What is the critical value range?
MIP
-20 to 0
What is the critical value range?
MEP
<40
What is the critical value range?
VC
<10-15
What is the critical value range?
VT
<5
What is the critical value range?
Respiratory rate
> 35 breaths/min
What is the critical value range?
FEV1
<10
What is the critical value range?
PEF
75-100
The PetCO2 for tidal breathing should be approximately ________.
4-6 mm Hg
PetCO2 is elevated for what type of patients?
- COPD
- Left sided heart failure (CHF)
- Pulmonary embolism caused by an increase in physiological dead space.
What disease process shows an increased gradient between PaCO2 and expired PC2 at the end of maximal exhalation?
Pulmonary emobolism
COPD and LHF does not show a difference.
Exhaled NO is currently used as a marker for _________.
Airway inflammation associated with asthma
Conditions associated with reductions of Exhaled NO: (5)
- Systemic hypertension
- Pulmonary hypertension
- CF
- Sickle cell anemia
- Ciliary dyskinesis
Conditions associated with elevated levels of Exhaled NO: (9)
- Asthma
- Bronchiectasis
- Airway viral infections
- Alveolitis
- Allergic rhinitis
- Pulmonary sarcoidosis
- Chronic bronchitis
- Systemic sclerosis
- Pneumonia
The most common method used to quantify the level of exhaled NO is _____.
Chemiluninescence
Exhaled NO can be detected in exhaled gas in the range of ___.
7.8 to 41.1 ppb
The single breath CO2 is produce by the ______.
Integration of airway and CO2 concentration; it is presented on a breath-to-breath basis.
The mode of ventilation is determined by what three factors?
- Type of breath
- Targeted control variable
- Timing of breath delivery
Mandatory breaths are breaths for which the ventilator controls the:
- Timing
- VT
- Inspiratory pressure
For spontaneous breaths, what does the patient control?
- Timing
- VT
Volume and pressure not set by clinician; based on patient demand
Describe assisted breaths.
All or part of the breath is generated by the ventilator
What does it mean if the airway pressure rises above the baseline during inspiration?
The breath is assisted
What is the primary advantage of volume-controlled ventilation?
Guarantees a specific volume delivery and volume of expired gas.
What is the goal of volume-controlled ventilation?
Maintain a certain level of PaCO2
What vent mode is a protective lung strategy that is more comfortable for patients who can breath spontaneously?
Pressure control
Guess the mode
Either time-triggered or patient-triggered breaths are mandatory breaths; the patient is not generating any spontaneous breaths.
CMV
Guess the mode
The patient is allowed to breath spontaneous breaths between mandatory breaths.
IMV
Guess the mode
All breaths are spontaneous and therefore patient triggered.
CSV
When the breaths are patient triggered during CMV, the breaths are described as ____.
Assisted ventilation
When breaths are time-triggered, the breaths are described as ___.
Controlled ventilation
CMV
Breaths can be _____ or ____ triggered.
Time or patient-triggered
Controlled (time-triggered) ventilation is only appropriate when ____.
A patient cannot make an effort to breathe.
The maximum pressure limit during PC-CMV is typically set at ________ above the target or set pressure.
Approximately +10 cmH2O
Advantages of CMV (4)
- Set minimum VE with volume-targeted breaths
- May synchronize with patient efforts
- Patient can establish rate
- Full support for patient who are not spontaneously breathing
Disadvantages of CMV (6)
- Muscle atrophy may result.
- May not be tolerated in awake patients
- Asynchrony if flow and sensitivity not set correctly
- High mean airway pressure and related complications
- VE may decrease with changes in compliance or resistance
- Respiratory alkalosis if # of patient-triggered breaths is too high
Advantages of IMV (6)
- May lower mean airway pressure
- Used for weaning
- May reduce alkalosis
- Full or partial support can be adjusted to meet patient needs
- Sedation not required
- Variable WOB may maintain muscle strength
Disadvantages of IMV
- IMV and PSV may increase mean airway pressure
- May increase weaning time
- Asynchrony
- WOB may increase as mandatory rate is reduced
- Acute hypoventilation can occur with low RR
A pressure support breath is a _______ triggered, _________ limited, ________ cycled breath.
Patient triggered, pressure limited, flow cycled
A dual control mode that provides pressure-limited ventilation with volume delivery targeted for every breath.
Pressure augmentation (VAPS)
A key criterion for pressure augmentation is the ____.
Ability to initiate breaths, patient must also have a consistent RR.
What do you set in VC?
- Flow
- VT
- PEEP
- FiO2
- RR
What do you set in PC?
- I-time
- Inspiratory pressure
- PEEP
FIO2 - RR
PRVC delivers pressure breaths that are _________ triggered, _________ targeted and ______ cycled.
- Patient or time-triggered
- Volume-targeted
- Time-cycled
What mode does this describe?
If the volume delivered is less than the set VT, the ventilator increases pressure progressively over several breaths until the set and the targeted VT are about equal.
Pressure-Regulated Volume control (PRVC)
Volume support ventilation (VSV) is very similar to ____.
PRVC
Unlike PRVC, VSV is _____ cycled.
Flow
Mandatory Minute Ventilation has been used primarily for ____.
Weaning patients off the ventilator
Explain MVV.
Ventilator provides whatever part of minute ventilation the patient is unable to accomplish by increasing breathing rate or the preset pressure.
What alarms are typically set for MVV?
- Low VT
- High RR
Because these parameters suggest an increased WOB.
Proportional Assist Ventilation
The amount of pressure the ventilator produces depends on what two factors?
- The amount of inspiratory flow and volume demanded by the patient’s effort
- The degree of amplification selected by the clinician
PAV is a ______ system.
Positive feedback
What are some factors that may contribute to extubation failure? (14)
- Type of patient (medical vs. surgical)
- Older age
- Severity of illness at weaning onset
- Repeated or traumatic intubations
- Use of continuous IV sedation
- Duration of mechanical ventilation
- Female gender
- Anemia
- Need for transport out of the ICU
- Initial severity of illness
- Indication for MV
- Protocol-directed weaning
- Mode of ventilator support before extubation
- Duration or # of SBTs before extubation
Physiological Parameters for Weaning and Extubation of Adults
VC
> 15 mL/kg
Physiological Parameters for Weaning and Extubation of Adults
VE
<10-15 L/min
Physiological Parameters for Weaning and Extubation of Adults
VT
> 4-6 mL/kg (IBW)
Physiological Parameters for Weaning and Extubation of Adults
Frequency (RR)
<35 breaths/min
Physiological Parameters for Weaning and Extubation of Adults
RSBI
<60-105 breaths/min/L
Physiological Parameters for Weaning and Extubation of Adults
Ventilatory pattern
Synchronous and stable
Physiological Parameters for Weaning and Extubation of Adults
Pimax
< -20 to -30 cmH2O
Physiological Parameters for Weaning and Extubation of Adults
P 0.1
> 6cmH2O
The set up for T-piece weaning includes:
- Heated humidifier with a large reservoir
With pressure support ventilation, what does the patient control? (3)
- RR
- Timing
- Depth of each breath (VT)
In general, there is a pressure support level of _________ for patients who meet weaning criteria.
5-15 cmH2O
ATC was designed to specifically do what?
Reduce WOB associated with increased ET resistance
What three key points have evolved as criteria for weaning?
- The problem that caused the patient to require ventilation has been resolved
- Certain measurable criteria should be assessed to help establish a patient’s readiness for discontinuation of ventilation
- SBT should be performed to establish readiness for weaning
Physical signs and measurements of increased WOB (9)
- Use of accessory muscles
- Asynchronous breathing
- Nasal flaring
- Diaphoresis
- Anxiety
- Tachypnea
- Substernal and intercostal retractions
- Measured WOB >15% of total O2 consumption
- Measured WOB >1.8 kg/m/min
Clinical Signs and Symptom Indicating Problems During a SBT (7)
- Deterioration of arterial blood gas values and O2 saturations measured by pulse oximeter (SpO2)
- Diaphoresis
- Sudden onset PVCs
- VT decreases below 250-300 mL
- BP changing significantly (a drop of 20 mmHg systolic, a rise of 30 mm Hg systolic, systolic values above 180 mm Hg, a change of 10 mm Hg diastolic)
- HR increasing 20% or exceeds 140 bpm
- Anxious
Criteria for Instituting NIV after Failure to Wean From Invasive MV in Extubated Patients (8)
- Optimum nutritional status
- Functioning GI tract
- Low FiO requirements
- Minimal airway secretions
- Hemodynamic stability
- Strong cough reflex
- Can tolerate SBT for 10-15 mins
- Resolved problem leading to respiratory failure
Hazards and Complications of Removal of the ET tube (11)
- Hypoxemia
- Hypercapnia from airway obstruction
- Tracheal, vocal card, laryngeal edema
- Laryngospasm
- Bronchospasm
- Aspiration
- Respiratory muscle weakness
- Hypoventilation
- Excessive WOB
- Postextubation pulmonary edema
- Development of atelectasis
How does nutrition play a role in the weaning process?
Overfeeding of carbohydrate calories leads to increased CO2 production.
Ultimately, the most important beneficial outcome of a tracheostomy is ___.
The potential to facilitate discontinuation of MV support.
What are some patient types that may benefit from a tracheostomy? (5)
- Those who require high levels of sedation to tolerate ETs
- Those with marginal respiratory mechanics and who may have tachypnea as a result
- Those in whom lower resistance may reduce the risk for muscle overload
- Those who may gain psychological benefit from the ability to eat, talk and have greater mobility.
- Those for whom increased motility may aid physical therapy efforts
What type of patients are less likely to tolerate T-piece weaning? (3)
- Underlying heart disease
- Severe muscle weakness
- Inclined to panic due to psychological problems or preexisting lung conditions.
What begins, sustains, ends and determines the characteristics of the expiratory portion of each breath?
Phase variable
What are the two settings used for APRV?
- Time 1 (T1) controls the time high pressure is applied.
- Time 2 (T2) controls the release time, or time low pressure is applied
HFOV assists with _______________ and is most often used for ______.
HFOV assists with inspiration and exhalation and is most often used for infant lungs, can also be used for ARDS.
______________ is controlled by an electronically operated valve that measures flow passing through the ventilator circuit during a specific interval.
Volume limiting
High PVR is usually associated with ___.
Hypoxemia
Which system act as a reservoir for the circulatory system?
Venous system
Which system allows for precise control over the direction and amount of blood flow to a given organ or area of tissue?
Capillary system
Higher than normal PetCO2 can be caused by: (3)
- Respiratory center depression
- Muscular paralysis
- COPD
Lower than normal PetCO2 can be caused by: (3)
- Pulmonary embolism
- Excessive PEEP
- Any disorder marked by pulmonary hypoperfusion
“Curare cleft” during phase III is a positive sign that a paralyzed patient is _____.
receiving insufficient NMBAs.
Changes in the contour of the capnogram can be used to detect: (7)
- Increases in dead space ventilation
- Hyperventilation/Hypoventilation
- Apnea or periodic breathing
- CO2 rebreathing
- Inadequate NMBAs
- Detect esophageal intubation
- Monitor the effectiveness of gas exchange during CPR
What ventilator mode uses two pressures and was originally used to improve oxygenation?
APRV
Where does electrical impulse travel the fastest?
Purkinje fibers
What is this mode of ventilation?
- Patient-triggered
- Pressure-limited
- Flow-cycled
Pressure support ventilation
