week 2 hemodynamics

Question 1

define hemodynamics

Answer 1

Study of blood flow and the forces involved in circulating blood through the body.

Question 2

how does blood move through the heart and lungs

Answer 2

From the body (unoxygenated)
1.Superior and inferior vena cava
2.R.heart
3.Pulmonary artery
4.Lungs (oxygenated)
5.Pulmonary veins
6.L.heart
7.Aorta
8.Body

Question 3

how many chambers is the heart divided into

Answer 3

4 chambers
-two artias
-two ventricles

Question 4

explain how the body enters the heart and out into the body

Answer 4

Blood enters body through superior/inferior vena cava→R.atria→tricupid valve→R.ventricle→pulmonary valve→pulmonary artery→lungs
Once oxygenated: blood returns from lungs→pulmonary vein→L.atria→mitral valve→L ventricle→aortic valve→aorta→pumped out to the body

Question 5

what is CO

Answer 5

cardiac output
-qauntity of blood the L ventricle pumps into the aorta each minute, key indicator of heart performance

Question 6

what is CO determined by

Answer 6

1. peripherial circulatory factors that affect venous return
   -vascular resistance and blood volume
   -hypertension
   -hypovolemia
2. hearts ability to pump the amount of blood it receives through the veins
   -heart failure

Question 7

what is venous return (VR)

Answer 7

qauntity of blood the veins return to the right atrium each minute

Question 8

define Stroke volume (SV)

Answer 8

amount of blood pumped w/each heart beat, measured by echocardiogram

Question 9

why should CO equal VR

Answer 9

1.inorder for circulatory to work efficiently
2.essential for maintain consistent blood flow
1. what is pumped on the left must return to the right side

Question 10

what is SV (stroke volume ) influenced by

Answer 10

1. preload- how much heart stretched before contraction

2.afterload-resistance heart faces when pumping

3.contractility- force the heart uses to contract

Question 11

define preload

Answer 11

occurs during diastole-ventricles fill
-ventricular muscle fibers stretch and allows blood to fill before contraction

-↑VR=↑preload=↑SV
-more blood returns, ventricles fill more and stretch, pump more blood out

-ventricular pump all blood received without allowing pooling in the atria and veins

Question 12

define afterload

Answer 12

occurs during systole-heart contracts
1. resistance to ventricular outflow–ventricles must overcome pressure in the arteries to eject blood
-resistance opposing ejection of the ventricular SV into the pulmonary artery or the aorta

Question 13

which factors affect blood pressure and affect afterload

Answer 13

1. vasoconstriction- increase afterload
2. vasodialtion-decrease afterload

Question 14

what happens when there is an abrupt increase in afterload

Answer 14

causes temp decrease SV for a few beats causing blood to pool.

how does heart compensate?
-muscle fibers stretch more
-big contraction to restore normal SV

*keep in mind-increase in afterload=increase in myocardial work& oxygen consumption

Question 15

define contractility and ejection fraction (EF)

Answer 15

1. hearts response to changes in preload and afterload
   -force of the shortening of muscle fibers

Question 16

preload vs CO

Answer 16

-greater the heart contractility
-increase SV for preload
-greater the demand for myocardial workload and oxygen consumption

Question 17

what is the venous return curve

Answer 17

• understand how changes in blood volume affect CO

Question 18

what happens to CO in hypervolemia

Answer 18

increase in blood volume
-more filling=more stretch
-increase mean circulatory filling pressure
-CO increases

Question 19

what happens to CO in hypovolemia

Answer 19

decreased blood volume
-less filling=less stretch
-decreased mean circulatory filling pressure
-decrease CO

Question 20

define what happens to venous return in arteriolar resistance

Answer 20

1. decrease in arteriolar resistance
   -allows more blood to flow through body to the R. atria
   -higher CO

2.increase in arteriolar resistance
-reduce blood to return the the R. atria
-lower CO

Question 21

define what the pressure gradient is

Answer 21

-pressure gradient b/w systemic capillaries (7mmHg) and right atrial pressure (0mmHg)

-creates forces to move the blood through the veins and into the right atrium

Question 22

normal circulation what is the R.atrial pressure and the CO/VR

Answer 22

R.atrial pressure= 2 mmHg

CO/VR=5L/min

Question 23

effects of contractility changes: increase contractility

Answer 23

-decrease RAP
-Increase CO

Question 24

effects of contractility changes: decrease contractility

Answer 24

-increase RAP
-decrease CO

Question 25

effects of blood volume changes: increase blood volume

Answer 25

-increase RAP -increase CO

Question 26

effects of blood volume changes: decrease blood volume

Answer 26

-decrease RAP -decrease CO

Question 27

what happens when the heart loses sudden contractility like in acute myocardial infarction (AMI)

Answer 27

1.Abrupt reduction in the heart's contractility and pumping ability (usually left ventricle) 2.Cause CO to sharply decrease 3.Blood pools in the left atrium, then to the lungs, and eventually the right ventricle and atrium 4.Creates acute uncompensated heart failure 5.New low-flow state develops and CO=VR again

Question 28

how does the body respond to an acute uncompensated heart failure

Answer 28

1. Blood volume increases due to the kidneys conserving water as a response to the low BP 2. Compensated heart failure -Improved contractility -Vasoconstriction to increase blood pressure -Renal fluid retention

Question 29

what is a pulmonary artery catheter

Answer 29

1. used to measure hemodynamic variables 2. promixal port -R.atrium -measures CVP/RAP 3. distal port -pulmonary artery -PAP directly -PCWP indirectly

Question 30

values hemodynamics

Answer 30

CVP: 2-6, R heart PAP: 20-30/ 6-15, lungs mPAP: 10-22 PCWP: 4-12, L heart QT/CO: 4-8, system, calculated thermodilution CI: 2.5-4.0L/min/m2

Question 31

what is PVR

Answer 31

1. pulmonary vascular resistance-resistance in the pulmonary circulation -increase PVR=pulmonary hypertension -decrease PVR=pulmonary hypotension

Question 32

what is SVR

Answer 32

1. systemic vascular resistance- resistance in the systemic circulation -increase SVR=systemic hypertension (stress on left heart) - decrease SVR=systemic hypotension

Question 33

define what CI (cardiac index) is

Answer 33

people of different sizes can be compared by indexing the cardiac output to BSA 1. CI=CO/BSA -CI<2.5L/min/m2= decreased heart function

Question 34

what is the significance of PCWP

Answer 34

PCWP>18mmHg-early signs of pulmonary edema PCWP>25mmHg-obvious evidence of pulmonary edema

Question 35

quadrants

Answer 35

1.normal or hyperdynamic state (septic shock) -CI is N or↑, PCWP is low 2. fluid overload -high PCWP and N or↑ CI 3.hypovolemia (hemorrhage or dehydration) or decreased contractility -low CI and low PCWP 4.acute left sided heart failure -high PCWP and low CI *look over picture.