Critical Care Monitoring Exam 4 Review

Physiology of BP (3)

• Without enough BP, tissues will not receive needed oxygen and nutrients

• However, high BP strains the heart and will eventually cause heart failure

• Arterial BP can change w/o affecting venous BP so must measure all BP’s

3 Factors that Control BP

• Heart

• Blood

• Vessels

Control of BP - Factor 1 (Heart) (2)

• Pump that creates pressure gradient

• Changes in the heart itself will directly affect BP:

  • Decr. HR or strength of contraction → BP decreases

  • Incr. HR or strength of contraction → BP increases

Control of BP - Factor 2 (Blood) (1)

• Amount of fluid in circulatory system affects BP:

  • Incr. blood volume → BP increases

  • Decr. blood volume → BP decreases

Control of BP - Factor 3 (Vessels) (1)

• Tone of the blood vessels affect BP:

  • Vasoconstriction → BP increases

  • Vasodilation → BP decreases

What is used to increase HR? (2)

• Epinephrine

• Atropine

What is used to decrease HR? (1)

• Beta blockers (lol)

What is used to increase blood volume? (1)

• IV fluids

What is used to decrease blood volume? (1)

• Diuretics

What is used to increase vessel tone? (1)

• Epinephrine

What is used to decrease vessel tone? (2)

• Ace inhibitors (“pril”)

• Nitroglycerin

Systemic Arterial BP Waveform (2)

• Normal 120/80

• Dicrotic notch represents closure of the aortic valve

Rule of 4’s

• Heart has 4 chambers

• Each chamber serves 1 of the 4 circulatory branches:

1. LV - systemic arteries

2. RA - systemic veins

3. RV - pulmonary arteries

4. LA - pulmonary veins

• Each chamber and connecting artery or venous system has its own BP - 4 pressures

1. LV - systemic arteries - arterial BP

2. RA - systemic veins - CVP

3. RV - pulmonary arteries - PAP

4. LA - pulmonary veins - PCWP

• Hemodynamic measures each of these pressures

CVP, RAP, RVEDP, RV preload (6)

• Measures pressure in the systemic venous system

• Much lower than mean ABP

• Since most of blood is in the venous system, changes in the CVP reflect changes in vascular volume so →

• CVP used to monitor vascular fluid levels and right heart function

• Treat when > 12 mmHg

• Transducer at level of RA

PAP (2)

• Measures blood moving through the pulmonary arteries into the lungs

• Increases in PAP occur in lung disease → increased PVR

PCWP, PWP, PAOP, LAP, LVEDP, LV preload (4)

• When BTFDC “wedged” - no longer measures forward flow of blood

• Measures back pressure from pulmonary veins which are in direct communication with left heart

• PCWP monitors left heart (LV and mitral valve)

• Treat when > 12 mmHg (pulmonary edema with a sick heart, for a normal and healthy heart, greater than 18 you’ll start seeing pulmonary edema)

Condition CVP PAP PCWP and QT for Right Heart

• Increased CVP

• (N) or decreased PAP

• (N) or decreased PCWP

• (N) or decreased QT

Condition CVP PAP PCWP and QT for Lung Problems

• Increased CVP

• Increased PAP

• (N) or decreased PCWP

• (N) or decreased QT

Condition CVP PAP PCWP and QT for Left Heart

• Increased CVP

• Increased PAP

• Increased PCWP

• Decreased QT

Condition CVP PAP PCWP and QT for Hypervolemia

• Increased CVP

• Increased PAP

• Increased PCWP

• Increased QT

Condition CVP PAP PCWP and QT for Hypovolemia

• Decreased CVP

• Decreased PAP

• Decreased PCWP

• Decreased QT

Hansen’s Helpful Hint #1 (2)

• Increased PAP + normal PCWP = lung disease

• Increased PAP + Increased PCWP = left heart problems

Hansen’s Helpful Hint #2 (1)

• PAd - PCWP: If > 5 mmHg = increased PVR

Hansen’s Helpful Hint #3 (1)

• PCWP cannot be > PAd

Helpful Hint #4 (1)

• Hypovolemia is the only condition that will decrease your pulmonary capillary wedge pressure

Trivia to Remember (5)

• Preload = ventricular filling volume/pressure

• Afterload = pressure after

• BTFDC tip should lie in a Zone III artery

• QT decreased → O2 extraction increased → PvO2, SvO2 decreased, CvO2 decreased → C(a-v)O2 increased

• SvO2 is the best indicator of tissue oxygenation

Normal MAP (Mean Arterial Pressure)

93-94 mmHg

Normal CVP (Central Venous Pressure)

2-6 mmHg

4-12 cmH2O

Normal PAP (Pulmonary Artery Pressure) and Normal mean PAP

PAP: 25/8 mmHg

Mean PAP: 13-14 mmHg

Normal PCWP (Pulmonary capillary wedge pressure)

4-12 mmHg