Hemodynamics

Question 0

How is Preload measured on the right side of the heart? What is the normal value?

Answer 0

Measurement of Preload on the right side of the heart = CVP or RAP (2-6 mmHg).

Question 1

Describe the Frank Starling Law of the heart.

Answer 1

Frank Starling Law - The more you stretch the myocardial fibers, the stronger they contract (rubber band effect), the greater you stretch a rubber band, the harder the snap. However, over stretching the fibers will produce a lower stroke volume.
Therefore, as EDV ⬆, the stroke volume ⬆

Question 2

How is Preload measured on the left side of the heart? What is the normal value?

Answer 2

Measurement of Preload on the left side of the heart = Pulmonary Artery Wedge Pressure (PAWP - catheter sits in the pulmonary artery) or LAP - 6 to 12 mmHg.

Question 3

Define Afterload, how is it usually measured? What are the normal values?

Answer 3

Afterload - Refers to the forces opposing left ventricular ejection. Common measurements of resistance to arterial flow are: SVR (800-1200 dynes) and BP (90/60-140/90).

Question 4

Describe the difference between the 3 following types of Distributive shocks:

1) Anaphylaxis
2) Neurogenic
3) Septic

Answer 4

1) Anaphylactic - Allergic rxn causing massive vasodilation
2) Neurogenic - Loss of nervous system control of arterioles causing massive vasodilation.
3) Septic - Bacterial infection of the blood, causing massive vasodilation.

Question 5

Define Systemic Vascular Resistance Index (SVRI). What is the normal range? How is it calculated?

Answer 5

SVRI = SVR indexed to BSA; individualizes SVR for each person based on BSA (2000-2,400). 
SVR = 80 x (MAP - RAP)/CO
SVRI = 80 x (MAP - RAP)/CI

Question 6

How is Cardiac Output (CO) calculated? What is the normal range?

Answer 6

CO = HR x SV (normal range = 4 to 6 L/min)

Question 7

What does the “Cardiac Index” (CI) measure? How is it measured ad what is the normal range?

Answer 7

CI is the ratio of cardiac output to body size. CI = CO/BSA (normal: 2.5 to 4L/min).

Question 8

What is the normal range for MAP? What value is mandatory to maintain minimal perfusion of vital organs.

Answer 8

Normal - 70 to 105 mmHg

60 mmHg is necessary to maintain minimal perfusion of vital organs

Question 9

(T/F) PTs are laid supine during insertion of a central line and the same supine position is maintained when the Cather is removed. Why or why not?

Answer 9

True - The supine position minimizes the possibility of an air embolism.

Question 10

What is the Phlebostatic Axis? What is it’s significance and where is it anatomically located?

Answer 10

Phlebostatic Axis - the reference point that is considered “zero” for the measurement of all central venous and pulmonary measurements. The Phlebostatic Axis is found at the 4th intercostal space, midway between the anterior and posterior chest wall (at the level of the right atrium).

Question 11

What does Pulmonary Systolic and Diastolic pressure measure and what are their normal ranges?

Answer 11

1) PASP - RV ejection (normal: 20-30 mmHg)

2) PADP - Vascular tone (normal: 8-15 mmHg)

Question 12

What is the Pulmonary Artery Occlusive Pressure and what is it’s normal range?

Answer 12

PAOP is the same as LAP, PAWP and LVEDP (normal: 6-12 mmHg)

Question 13

What is the Pulmonary Artery Pressure and what is the normal range?

Answer 13

PAP - reflects pressures in the pulmonary circulation (normal: 20-30/5-15 mmHg)

Question 14

How is Systemic Vascular Resistance calculated?

Answer 14

SVR = 80 x (MAP - RAP)/CO