RESP 200 quiz 1 study guide

equations to know:

• Stroke Volume

• Cardiac Output

• Ejection fraction

• SVR

• MAP

• SV = EDV – ESV

• CO = SV x HR

• Ejection fraction (EF) = SV/EDV

• SVR = (MAP – RAP) / CO

• SVR = [(MAP – RAP) / CO] × 80 in dyn·sec/cm⁵

• MAP = [(2 × DBP) + SBP] / 3

• MAP = volume / capacity

normal values for equations

• SV= 60-100ml

  • normal is 70 ml

• CO= 4-8L/min 

• EF= 65%

  • (70ml/110ml)

• SVR= 800 to 1,200 dynes·sec/cm⁵

• MAP= 80-100mmHG

• EDV=110-120ml

• ESV=40-50ml

vocabulary to know

• Regurgitation AKA Regurg: Backflow of blood through a leaky/malfunctioning valve

• Stenosis: Narrowing of or constriction between the two left heart chambers

• Preload: Volume and stretch/pressure of blood in the ventricles after the end of diastole (the filling phase) before the heart contracts that determines how much the myocardium will stretch

• Stroke Volume= EDV-ESV: End diastolic volume, end systolic volume the amount of blood pumped with each heartbeat

what is stroke volume (SV)

• the amount of blood pumped with each heartbeat

• volume of blood pumped out by a ventricle of the heart during each heartbeat.

• The heart does not eject all of the blood it contains during systole

• difference between the EDV and the ESV is _______

equation for stroke volume

EDV – ESV

normal value: 60 - 100 ml

• normal is 70~

• normal EDV: 110-120 ml

• ESV=40-50ml

define End-Diastolic Volume (EDV)

The amount of blood inside a ventricle at the end of diastole, immediately before contraction.

define End-Systolic Volume (EDV)

The amount of blood remaining inside a ventricle after contraction.

A patient's end diastolic volume is 100 ml and the stroke volume is 40 ml. Which of these conditions is most likely causing his low ejection fraction? 

Patient has chronic methamphetamine use and this has damaged the patient's heart

While 300 ml is some blood loss, it is not that much when considering normal cardiac output of 5 liters/minute. This isn't enough to account for such a low EF. The most likely reason is a damaged heart. 

what are 3 things are stroke volume impacted by

1. Preload

2. Afterload

3. Contractility

what is preload

• venous return. Volume and stretch/pressure of blood in the ventricles after the end of diastole (the filling phase) before the heart contracts that determines how much the myocardium will stretch

• affected by _________ mechanism

what is the frank sterling mechanism

• Greater the stretch of ventricular muscles during diatole, the stronger the contraction

• Smaller stretch makes a smaller contraction

  • (lower volume → lower Stroke volume)

• relates to preload and stroke volume

• As ventricular filling and myocardial stretch ↑, the force of contraction ↑, up to an optimal point.

• the heart contracts more forcefully when it is filled with more blood during diastole, meaning that the more the ventricular muscle cells are stretched, the more forcefully they contract

what is afterload

• the resistance the ventricles pump against and must overcome during systole to eject blood into the arteries

  • so if there is more _______, it’s harder for the ventricles to eject their SV.

• represents the sum of all external factors opposing ventricular ejection including:

  • tension in the ventricular wall

  • peripheral resistance

• RV _____ = PVR

• LV _____ = SVR

• ↑ resistance → ↓ SV

  • This usually does not occur because contractility increases to maintain the SV and CO

    
    

what is contractility

strength or force of the myocardium contraction produced at any EDV

• ↑ in _______ results in greater EF for any EDV

what happens when afterload and contractility ↑ together

SV stays the same

what 2 factors affect contractility

• positive inotropes

• negative inotropes

how do positive inotropes affect contractility

• ______ drugs↑ the contractility of heart muscles

• They may be used when the heart is too weak to pump enough blood.

• ↑ contractility to ↑

  • blood flow

  • organ perfusion

  • ↑ SV

  • ↑ CO

how do negative inotropes affect contractility

• _______ are drugs that ↓ contractility of heart muscles and ↓ workload

define CO

The amount of blood pumped by the heart each minute.

what is the difference between SV & CO

Cardiac output is the total volume of blood pumped by the heart per minute, while stroke volume is the amount of blood pumped out with each single heartbeat.

what is the equation for cardio output

SV x HR

• SV is represented in Liters

• HR is represented per min

• normal value = 4-8 L/min

example equation for CO:

SV= 0.075 liters

HR= 90/min

example:

• 0.075 liters x 90/minute

  • _____ = 6.75 liters/minute

example mini clinic for CO

27-year-old female motorcycle rider, 60 kg, is hit by a motor vehicle. She has lost considerable blood at the scene. In the ED her RR = 32. An emergency ECHO is performed and indicates SV = 40 ml.

Her HR = 150. Calculate her CO.

Why is her heart beating so fast?

Do you think her BP would be high, low, normal or hard to know?

• CO = HR x SV

  • = 150/min × 40 ml

    • = 6,000 ml/min → 6.0 L/min CO

• initial ↑ or maintenance in BP then decreases significantly

• Her severe tachycardia is a primary compensatory response to hypovolemic shock caused by acute hemorrhage.

  • ↓ SV: Significant blood loss ↓ venous return and EDV (preload). This causes SV to ↓ significantly

  • Sympathetic Stimulation: Arterial baroreceptors detect the loss of stretch/volume and activate the sympathetic nervous system, triggering a surge of epinephrine and norepinephrine.

  • Perfusion Maintenance: To keep cardiac output from collapsing her body reflexively ↑ HR to pump what little circulating volume remains to vital organs.

• 
  

An adult female whose normal pulse is about 70 beats/minute. She has no cardio myopathy. Her heart rate increases to 105. The most likely cause is:

Excitement because she just got her diploma and graduated from RT school

While blood loss would kick the heart into gear in terms of heart rate, 50% blood loss would require far more than 105 beats/minute to keep the patient alive. For this mild increase in heart rate, the most likely option is the emotional response to graduation that made her happy/excited. 

Negative chronotropes will slow her heart. 

Parasympathetic system should slow her heart not speed it up

what factors affect HR & cardiac output?

• the factors affecting HR are mainly neuronal or hormonal

• Factors that ↑ HR are called

  • positive chronotropic drugs

• Factors that ↓ HR are called

  • negative chronotropic drugs

what do positive chronotropes do

• ↑ HR by changing the electrical signals in the heart's pacemaker cells (SA node)

  • speed up the depolarization (firing rate) of these pacemaker cells.

  • causes the heart to beat more times per minute

what are examples of positive chronotropes

• Activation of the sympathetic nervous system triggers ↑ HRsuch as:

  • EPI (adrenaline)

  • NE

  • atropine

  • dobutamine

  • dopamine

what do negative chronotropes do

• ↓ HR by slowing down the electrical firing rate of the heart's natural pacemaker

• lengthen the time it takes for pacemaker cells to trigger an electrical signal

  • resulting in fewer beats per minute

• ↓ the workload and oxygen demand of the heart muscle

what are examples of negative chronotropes

• Beta-Blockers: block adrenaline to ↓ HR

  • metoprolol

  • atenolol

  • adenosine

• Calcium Channel Blockers

  • diltiazem ↓ electrical conduction speed and heart rate.

• Ivabradine Inhibits pacemaker

what is the equation for SVR

• main equation:

  • (Mean Aortic Pressure – Right Atrial Pressure ) / Cardiac Output

  • expressing in mmHg/L/min

• if in expressed in dynes/sec/cm^-5  , multiply by 80

  • [(MAP – RAP ) / CO] x 80 = SVR

• normal _____= 800 to 1,200 dynes·sec/cm⁵

example of SVR equation:

Patient has a MAP of 100 mmHg, RAP of 5 mmHg, and CO of 5 L/min. What is the SVR?

• SVR = (100 – 5) / 5

  • SVR = 19 mmHg/L/min

• if in dynes·sec/cm⁵

  • 19 × 60 = 1520 dynes·sec/cm⁵

what is systemic vascular resistance (SVR)

• the sum of all opposing forces to blood flow through the systemic circulation.

  • the force or resistance that the heart must push against to send blood through the body's blood vessels

• The _____ must equal the pressure difference between the circuit’s beginning and end, divided by the flow.

  • Flow = cardiac output (CO)

    
    

what is the difference between SVR and MAP?

Mean arterial pressure (MAP) is the average blood pressure in your arteries during a single heartbeat (driving pressure), while systemic vascular resistance (SVR) is the resistance or tightness of the blood vessels that blood must push through

example mini clinic for SVR:

31-year-old gets into a verbal fight outside a bar at 1:30 AM. It gets heated and he is stabbed 8 times in the lower quadrant. Paramedics drive to the site at 1:45 AM and estimate the patient’s blood loss is ~1.5 liters.

• Question 1: If normal cardiac output is ~ 5 liters. How is this patient going to compensate for this loss of blood?

• Question 2: How will this impact HR?

• Question 3: How do you think the SVR will be impacted by this blood loss?

• BONUS QUESTION 4. : What happens to oxygenation?

1. baroreceptors react

2. ↑ HR and BP initially then will ↓

3. ↑ SVR initially then will ↓

4. ↓ oxygenation

   1. activates chemoreceptors

what is RAP

• right atrial pressure (or CVP) = end pressure of systemic circulation

  • Pressure in the central veins near the right atrium. CVP closely reflects right atrial pressure

• The pressure inside the RA.

  • reflects how well blood returns from the body and how effectively the heart pumps it forward

what is mean arterial pressure (MAP)

• beginning pressure of systemic circulation

• represents the average driving pressure that moves and pushes blood through the systemic circulation to perfuse the organs.

• Alter capacity Vasoconstriction=↑ BP 

how can we improve MAP

• ↑ in

  • vasopressors

  • IV fluids

what happens when ↓ MAP

↓ Organ Perfusion

↓ Oxygen Delivery to Tissues

Risk of Organ Dysfunction/Failure

Important organs affected include:

• Brain

• Heart

• Kidneys

equation for MAP

____ = VOLUME / CAPACITY

use this equation:

• (2 x DBP) + SBP / 3

  • DBP multiplied by 2 bc diastolic phase lasts longer than systolic phase

• normal value: 80 – 100 MMHG

  • critical below 65

    • damages organs

example equation for MAP:

1. BP= 120/75

2. BP= 70/40

3. BP= 140/90

• (2 x DBP) + SBP / 3

  • (2 × 75) + 120 / 3 = 90 mmhg

• (2 x DBP) + SBP / 3

  • (2 × 40) + 70 / 3 = 50 mmhg

• (2 × 90) + 140 / 3 = 107~ mmhg

what can ↑ MAP volume

• to ↑ the volume

  • We can add fluids

  • ↑ Blood Volume

  • ↑ Venous Return

  • ↑ Preload

  • ↑ SV

  • ↑ CO

what medications can ↑ MAP

• medications

  • Vasopressors

  • EPI

  • NE

  • dopamine

what can ↓ MAP volume

• ↓ HR

• ↓ Contractility

• ↓ Preload

• ↓ SVR through vasodilation

what can alter MAP

• Vasoconstriction

  • Constriction of the smooth muscles in the peripheral blood vessels

  • Causes blood pressure to ↑ even though blood volume is the same

• Vasodilation

  • Dilation of the smooth muscles in the arterioles (per book, but also occurs in veins and arteries)

  • Causes blood pressure to ↓ even though blood volume has not changed

what hormones affect MAP and BP that act on arterioles:

• ANGIOTENSIN II

  • ↑ SVR — vasoconstriction & ↑BP

• ATRIA NATIURETIC PEPTIDE

  • ↓ SVR — vasodilation & ↓BP

what hormones affect MAP and BP that act on kidneys

• ALDOSTERONE ↑ Blood volume — water + salt

  • leads to heart failure

• CORTISOL ↑ Blood volume — water + salt retention

what hormones affect MAP and BP that act on arterioles & kidneys

• ANTIDIURETIC HORMONE (ADH)

  • ↑ Blood volume + ↑ SVR

    • leads to heart failure

what is ejection fraction

• The % of the EDV ejected/pumped from the left ventricle during contraction with each heartbeat

• Help determine how

  • well the heart is functioning

  • well the ventricle squeezes

  • much CO may be affected 

what is the difference between ejection fraction, CO, and SV

Stroke Volume (SV)	Cardiac Output (CO)	Ejection Fraction (EF)
Unit of Measurement	Milliliters mL per beat	Liters L per minute	Percentage %
What it tells you	The pumping volume per single beat	The total workload per minute	The efficiency or squeezing power
Main Connection	Feeds into the calculation for Cardiac Output	Depends on Stroke Volume and heart rate	Derived from stroke volume and filling volume

what increases ejection fraction

• ↑ in contractility

  • from ↑ positive inotropes

what happens if ejection fraction is ≤ 30 %

• pt’s exercise tolerance will become severely limited

  • hypoxia

• heart has ↓ pumping ability which can lead to

  • ↓ CO

  • hypotension

  • pulmonary congestion 

  • Crackles, Increased WOB, Dyspnea, Decreased PaO2

• Very Low _____

  • Patient may be at higher risk for heart failure and low perfusion 

• Low EF → poor pump → blood backs up → pulmonary edema (L side heart failure) → impaired oxygenation.

• can be affected by aging and heart disease

  • risk for heart stiffness increases

how does aging affect ejection fraction

• _____

  • can’t support body

  • weakening the heart's squeeze or leave the percentage normal while making the heart too stiff to fill properly

  • heart muscle can thicken and stiffen slightly over time. This makes it harder for the heart to fill up with blood before it pumps

  • the heart cannot increase its pumping efficiency as well during hard exercise, lowering peak performance

• Less filling 

• Less end diastolic volume 

• Less cardiac output

• Increased afterload 

how do heart diseases affect ejection fraction

• heart disease

  • reduced ______

    • Conditions like heart attacks or weak heart muscles damage the pumping power. The heart cannot squeeze hard enough, causing the _____ to drop below normal (often under 40%)

  • preserved ______

    • Conditions like high blood pressure, diabetes, or obesity make the heart very stiff. The heart still squeezes well enough for the _____ percentage to look normal (50% or higher), but it cannot relax and fill with enough blood

what is the equation for the ejection fraction (EF)

SV/EDV

• note: multiply by 100 to convert to a percentage

• Normal value = ~ 65% (70 ml / 110 ml)

example equation for ejection fraction

SV=80 mL

EDV=140 mL

80 mL / 140 ml = 57%

define pulse pressure

The difference between systolic and diastolic blood pressure.

define SA node

The heart’s normal pacemaker. It initiates the electrical impulse that begins atrial depolarization.

define AV node

Receives the electrical impulse from the atria and slows it down before transmitting it toward the ventricles.

what is the significance of AV valves

• During ventricular contraction, the tricuspid and bicuspid/mitral valves close to prevent blood from flowing backward into the atria.

• lies between the atria and the ventricles – they

  ensure one-way blood flow

• Right side:

  • Right Atrium → Tricuspid Valve → Right Ventricle

• Left side:

  • Left Atrium → Bicuspid/Mitral Valve → Left Ventricle

To open the semilunar valve and get blood to flow in the aorta, what needs to happen to the pressures

overcome 80mmhg in ventricles

As soon as pressures in the ventricles exceed pressures in the aorta, what happens

mitral valve closes first followed immediately by tricuspid valve

When the ventricular pressure exceeds aortic pressure, the mitral and tricuspid valves close (in that order) so blood will exit through the aorta 

what is Mitral valve Regurgitation, AKA “regurg”

• Back flow of blood through a leaky or malfunctioning valve

• Can be asymptomatic, but as it progresses, pt. can/will experience

  • SOB

  • fatigue

  • palpitations

  • swelling in lower extremities

what is Mitral Valve Stenosis

• Narrowing of or constriction between the LA & LV

• Causes ↑ in blood flow resistance from LA into LV

• blood backs up in the pulmonary circulation and leads to pulmonary edema.

  • stenosis → pulmonary backup → pulmonary edema

For a patient with symptomatic mitral valve stenosis, blood would most likely backflow to:

Pulmonary vein causing blood to back flow through the left atrium and into the pulmonary system causing congestion in the lungs

The mitral valve is between the left ventricle and atria. If it's stenotic and blood is backing up, it will backflow into the left atrium, through the pulmonary vein and into the pulmonary fields causing congestion. 

A patient with symptomatic mitral valve stenosis could experience the following: ( Select ALL that apply)

increased pressure in the left atrium from blood backing up

need for surfactant because the lung field is very dry

fluid in the alveoli and interstitial spaces

shortness of breath

increased cardiac output

pulmonary edema

need for supplemental oxygen

increased pressure in the left atrium from blood backing up

fluid in the alveoli and interstitial spaces

shortness of breath

pulmonary edema

need for supplemental oxygen

This question comes from mini clini p 204 in Egan's. As I said, if I discuss a topic in class, checking the book in that area could help you for the test. 

CO would not increase

Surfactant would not help this situation 

Thank you to the student who caught my error and noticed I did NOT check fluid in alveoli and interstitial spaces. This is a problem, too!

how can we treat mitral stenosis

• CPAP

• sometimes BiPAP

how do we treat mitral valve concerns

• surgery

• ECHO

• anticoagulants

• meds

what does the P wave represent

atrial contraction. also called atrial depolarization

• in electrocardiography is the first small upward bump on an EKG tracing. It shows electrical signals moving through the atria causing them to squeeze and pump blood into the ventricles

• triggers electrical impulses leading to atrial contraction

what does the QRS complex represent

ventricular contraction, also called ventricular depolarization

• It marks the main pumping action of the heart, sending blood to the lungs and the rest of the bod

what does the T wave represent

ventricular repolarization

• represents the recovery or repolarization of the heart's lower chambers (the ventricles) after they contract

Closure of semilunar valves causes the second heart sound

True

what are the two main coronary arteries arise from the root of the aorta

• Left coronary artery

• Right coronary artery

what does the LCA do

• ____ is positioned

  • underneath aortic semilunar valves

• ____ provides blood to

  • left atrium

  • left ventricle

  • majority of interventricular septum

  • half of interatrial septum

  • part of R atrium

what happens to an obstructed left coronary artery (LCA)

• When ____ becomes obstructed:

  • blood perfusion to L ventricle stops

  • ischemia and infarction occur, sometimes resulting in death

LCA obstruction → ↓ LV perfusion → ischemia/infarction

what are 2 common blood flow issues

• Myocardial ischemia

• Myocardial infarction (MI)

what is Myocardial ischemia

• Partial obstruction of coronary artery

• also called angina pectoris

• ↓ in oxygen supply to the tissue

what is Myocardial infarction (MI)

• Complete obstruction of coronary artery

• Sometimes called an infarct

• Causes death of heart tissue

3 types of coronary artery diseases (CAD) associated with gradual and sudden obstruction of the coronary arteries are

1. Unstable angina or angina pectoris

2. Non-ST segment elevation myocardial infarction (NSTEMI)

3. ST-segment elevation myocardial infarction (STEMI)

what are peripheral baroreceptors

• Pressure/stretch receptors that help regulate blood pressure.

• _______ respond to pressure changes and are located in:

  • Aortic arch

  • atrial walls

  • some thoracic and pulmonary veins

• maintains BP

  • short term

  • blood loss

  • stabbing

• These respond to volume changes

  • ______ output is directly proportional to vessel stretch

    • Negative feedback system: greater stretch causes:

      • venodilation

      • ↓ heart rate and contractility

what happens when BP falls in relation to baroreceptors

• ↓ Stretch of baroreceptors

• ↑ Sympathetic stimulation

• ↑HR

• ↑ Contractility Vasoconstriction compensation

what happens when BP rises in relation to baroreceptors

• ↑ Stretch of baroreceptors

• ↑ Vasodilation

• ↓ Sympathetic stimulation

• ↓ HR

• ↓ Contractility

what are chemoreceptors (type of peripheral baroreceptors)

• Located in

  • aortic arch

  • carotid sinus

• Respond to changes in blood chemistry (chemical component)

  • ↓ pH & PaO2 provides strong stimulus

  • ↑ H+ and PaCO2 also impact ______

• Major CV response to ______ stimulation is

  • ↑ HR

  • vasoconstriction

  • Occurs only when CV system is overtaxed: generally little effect

example mini clinic baroreceptos

27-year-old female motorcycle rider, 60 kg, is hit by a motor vehicle. She has lost considerable blood at the scene. She arrives in the ED, A & O only to person and place, RR = 32.

• An emergency ECHO is performed in the ED. Her SV = 40 ml. What do you think might happen to her HR?

• ↑ HR initially for compensation

  • will eventually ↓

• activation of baroreceptors for blood loss

• oxygen issue

how hemorrhaging and hypovolemia affect blood loss

• 10% blood loss

  • ↓ in

    • CVP

  • → ↑ in

    • low-pressure baroreceptor activity

    • sympathetic discharge

    • HR

    • ADH

  • BP maintained

• 20% blood loss

  • → further ↓ in

    • atrial receptor activity

  • ↑ in

    • sympathetic discharge

    • HR + ADH

    • peripheral vascular tone

  • venoconstriction slows the fall in CVP

define Arterial Compliance

The ability of the arteries to expand when blood is ejected into them and recoil when pressure decreases.

define Arterial Resistance

The opposition to blood flow produced mainly by the arteries and arterioles.

define RAAS

Renin-Angiotensin-Aldosterone System. A hormonal system involving the kidneys that helps regulate long-term blood pressure and blood volume.

define ACE

Angiotensin-Converting Enzyme. Converts angiotensin I into angiotensin II.

define BNP

B-Type Natriuretic Peptide. A hormone released in response to ventricular wall stretch that promotes sodium and water loss, helping reduce blood volume and blood pressure.

components of the cardiac cycle

1. Blood Fills the Heart

1. Deoxygenated blood from the body enters the right atrium, goes through the tricuspid valve, and enters the right ventricle.

2. Oxygenated blood from the lungs enters the left atrium, goes through the bicuspid/mitral valve, and enters the left ventricle.

3. During ventricular filling:

• Tricuspid and bicuspid valves are OPEN.

• Pulmonary and aortic semilunar valves are CLOSED.

2. P Wave – Atrial Depolarization

Atrial depolarization is followed by atrial contraction.

The atria contract and push the remaining blood into the ventricles.

3. QRS Complex – Ventricular Depolarization

Systole = Ventricular depolarization is followed by ventricular contraction.

As ventricular pressure increases above atrial pressure:

• Tricuspid valve closes.

• Bicuspid/mitral valve closes.

Isovolumetric contraction = The ventricles begin contracting while all four valves are temporarily closed.

4. Ventricular Ejection

• As ventricular pressure continues to increase:

• Right ventricular pressure becomes greater than pulmonary artery pressure when the Pulmonary semilunar valve opens.

• Left ventricular pressure becomes greater than aortic pressure when the Aortic semilunar valve opens.

Blood is now ejected from the ventricles.

5. T Wave – Ventricular Repolarization

• T wave = Ventricular Repolarization

Diastole = Ventricular repolarization is associated with ventricular relaxation

As ventricular pressure falls below arterial pressure:

• Pulmonary semilunar valve closes.

• Aortic semilunar valve closes.

6. Ventricular Relaxation and Refilling

• Isovolumetric relaxation = The ventricles continue relaxing while all four valves are temporarily closed.

Once ventricular pressure becomes lower than atrial pressure:

• Tricuspid valve opens.

• Bicuspid/mitral valve opens.

The ventricles begin filling again and the cardiac cycle repeats.

components of coronary circulation

The myocardium requires its own blood supply.

The two main coronary arteries are:

• Left Coronary Artery

• Widowmaker = Left Coronary Artery (LCA) obstruction

• Right Coronary Artery

The coronary arteries arise from the root of the aorta.

The left coronary artery supplies much of the left side of the heart, including the left ventricle.

• Decreased coronary blood flow:

↓ Blood flow → ↓ Myocardial oxygen → Ischemia

A complete loss of blood flow can result in myocardial infarction and death of heart tissue.

• Basic relationship:

• Partial coronary obstruction → Myocardial ischemia

• Complete coronary obstruction → Myocardial infarction