SM 143a - Clinical Hemodynamics and Ventricular Function

Question 1

List the normal pressures in each location (in mmHg)

RA:

RV:

PA:

Wedge:

LA:

LV:

Aorta:

Answer 1

RA: 6

RV: 24/6

PA: 24/12

Wedge: 6-12

LA: 6-12

LV: 120/(6-12)

Aorta: 120/60

Question 2

How does LVEDP increase help increase cardiac output?

Answer 2

Increasd LVECP -> increased preload (Frank-Starling law)

This increases the strength of cardiac contraction, which increases cardiac output

Question 3

In which type of shock is cardiac output most likely unaffected?

Answer 3

Distributive aka vasodilatory

Question 4

A patient is in shock.

They are cold, and they have a distended jugular vein.

What kind of shock is this?

What other physical exam findings would you expect?

Answer 4

Cardiogenic shock: Primary problem is low CO

May be caued by MI, acute PE, tamonade, CHF exacerbation

• Low cardiac output
• Vasoconstriction
  
  • Increased RAP (equal to CVP)
  • Increased SVR
• Decreased pulse pressure
• Poor capillary refill

(Adequate pressure, volume, but not enough CO)

Question 5

What are the contraindications for using a Swan-Ganz catheter in a patient?

Answer 5

ABE-VT

• Vascular access issues
• Left bundle branch block
• Acute pulmonary embolism
• Prosthetic valves
• RV or RA mass/thrombus

Question 6

How can we approximate LV afterload?

Answer 6

Mean Arterial Pressure (measure wtih cuff) or SVR

Question 7

How can cardiac output be determined via Swan-Ganz catheter?

Answer 7

• Thermodilution
  
  • Cold saline is injected through the proximal port of the catheter
  • Temperature profile is measured
  • Area under the curve approximates CO
• Fick method
  
  • Measure oxygen consumed by the body
  • Measure O2 removed from the blood
    
    • LA content - venous content
  • CO = O₂ consumed / O₂ removed from blood

Question 8

Why is a rise in RVEDP deleterious?

Answer 8

• Increased RVEDP
• -> Increasd Right Atrial Pressure
• -> Increased systemic pressure
• -> change Starling forces
• -> Fluid leads into interstitium
• -> Peripheral Edema

Question 9

A patient is in shock.

They are warm.

What kind of shock is this?

What other physical exam findings would you expect?

Answer 9

Distributive aka vasodilatory

Can be due to sepsis, anaphylaxis, neurogenic disorders, or adrenal insufficiency

• Vasodilation
  
  • Low SVR
  • Low PWCP
  • Low CVP (equal to Right Atrial Pressure)
  • Low blood pressure
• Increased CO

Question 10

Pulmonary capillary wedge pressure can be measured via Swan-Ganz catheter.

What is pulmonary capillary wedge pressure a proxy for?

Answer 10

Left atrial pressure, which is equal to LV filling (diastolic) pressure (if there is no valvular disease)

Can determine compliance and volume overload

Question 11

A patient is in shock.

They are cold, and their jugular vein is not distended.

What kind of shock is this likely to be?

What other physical exam findings would you expect?

Answer 11

Hypovolemic shock: Primary problem is low volume

• Low CVP (equal to RAP)
• Low CO
• Increased SVR

(Not enough blood volume to maintain BP, despite vasoconstriction)

Question 12

What is the equation for calculating pulmonary vascular resistance (PVR)?

Answer 12

Mean PAP = Mean Pulmonary Artery Pressure

PAWP = PCWP = Pulmonary Artery/Capillary Wedge Pressure = Left Atrial Pressure

[40-150 = normal; >240 = very abnormal]

Question 13

A patient is in shock. They have low RAP (equal to CVP)

Which types of shock are possible?

How would you differentiate between them?

Answer 13

Hypovelmic and distributive are possible

Hypovolemic: cold, low CO, high SVR

Distributive: warm, high CO, low SVR

Question 14

How can we measure RV preload?

Answer 14

Right Atrial Pressure, which is equal to Central Venous Pressure

Question 15

We can use a Swan-Ganz catheter to learn more about which apects of a patient’s hemodynamic status?

Answer 15

• Left atrial pressure
• Left ventricle diastolic pressure
• Cardiac output
• Assess shock
  
  • If it isn’t obvious using the warm/cold/wet/dry criteria
• Assess heart failure
• Assess pulmonary edema

Question 16

What is the equation for calculating systemic vascular resistance (SVR)?

Answer 16

MAP = Mean Aortic Pressure

CVP = Central Venous Pressure = Right Atrial Pressure

[Normal = 800-1200 wood units]

Question 17

How can we approximate RV afterload?

Answer 17

Mean pulmonary artery pressure (use PA catheter) or Pulmonary vascular resistance

Question 18

How can you differentiate between right ventricle and pulmonary artery wave forms?

Answer 18

• Right ventricle
  
  • Lower diastolic pressure (6 mmHg)
  • No dicrotic notch
• Pulmonary Artery
  
  • Higher diastolic pressure (12 mmHg)
  • Dicrotic notch is present

Question 19

If a patient in shock has increased SVR, which types of shock are possible?

How would you differentiate between the two?

Answer 19

Hypovolemic and cardiogenic are possible

Hypovolemic would have low RAP (equal to CVP)

Cardiogenic would have high RAP (equal to CVP)

Question 20

Why is a rise in LVEDP deleterious?

Answer 20

• Rise in LVEDP
• -> Rise in Left atrial pressure
• -> Increased capillary pressure in the alveolus
• -> Change in Starling Forces
• -> Fluid leaks into the alveoli
• -> Pulmonary edema

Question 21

How can we measure LV preload?

Answer 21

Measure left atiral pressure - approximiates LV end diastolic pressure

(Pulmonary capillary wedge pressure is a proxy)

Question 22

How can you differentiate between right atrium and pulmonary capillary wedge waveforms?

Answer 22

• Right Atrium
  
  • C wave is present
  • Lower pressure (~6 mmHg)
• Pulmonary Capillary Wedge (proxy for Left Atrium)
  
  • C wave is not present
  • Higher pressure (~6-12 mmHg)

Question 23

Why measure wedge pressure? Why not just measure the LV end diastolic pressure?

Answer 23

Measuring wedge pressure is safer for the patient and more convenient