PULM HTN LECTURE SLIDES Flashcards
Functions of bronchial circulation (2)
1) protects lung from infarction (PE, pneumonia)
2) can grow into diseased areas (intercostal arteries) -
Consequences of bronchial circulation
1) source of hemoptysis (cough up blood)
2) much of arterial flow drains into LA = shunt
what does bronchial circulation supply?
conducting arteries
bronchial circulation is ___ in origin
systemic
tissue beds have ___ to blood flow
resistance
circulation variables
driving force
flow
resistance
driving force = P
Blood flow = Q/CO
vascular resistance = PVR/SVR
combining pulm circulation variables into equation
PAP – LAP = CO * PVR
PAP: Pulmonary artery pressure
LAP: Left atrial pressure
CO: Cardiac output
PVR: Pulmonary vascular resistance
units of
CO
Pressures
PVR
CO = liters/min Pressure = mmHg PVR = woods unit
The following measurements are made in a patient:
Mean PA pressure = 25 mmHg
Left atrial pressure = 10 mmHg
Cardiac output = 5 L/min
What’s the pulmonary vascular resistance?
A. 1 Wood Unit
B. 2 Wood Units
C. 3 Wood Units
D. Cannot be determined
Answer = C (3 woods units)
25-10 = 5 x PVR
what is function of large elastic arteries
absorb pulsatile flow
what is function of muscular pulm arteries
regulate blood flow
steps in pulm circulation
1) arteries (run with broncholes)
2) capillary network
3) veins run with interlobular septae (lymphatics)
Difference between systemic vs. pulm circulation
Pulm circulation
Low resistance
Low elastance/High compliance
Low pressure
both have same CO = 5L/min
What’s DIFFERENT between the pulmonary and systemic vasculature?
A. The pulmonary circulation has lower resistance.
B. The systemic circulation has higher compliance.
C. The pulmonary artery pressure is higher.
D. The cardiac output.
A = The pulmonary circulation has lower resistance.
How do you measure PA pressure
Non-invasive echocardiography
why?
equation?
errors?
Looking at tricuspid valve regurgitation
RV becomes dilated so you get jet of blood backwards
in normal person you can’t measure
Simplified Bernoulli equation
P = 4 x V^2
= 4 x (3 m/s)^2
= 36 mm Hg (systolic) + RA pressure
Errors = +/- 10 mmHg common (greater)
How do you measure PA pressure
Pulm artery catheterization with Swan-Ganz Catheter
Method?
What do you measure?
1) Place catheter into boy
2) catheter drift thru body into RV and then exists pulm valve into vasculature
3) obstruct a small pulm artery
Make a static water column, because no movement distal to balloon (Q = 0, dP = 0)
= Pulm capillary wedge pressure
what is pulm capillary wedge pressure can be equal to?
~ LA pressure
~ LV EDP
Modern PA catheter used to measure what?
1) RA pressure
2) PA pressure
3) PCP
4) CO via thermodilution or laser doppler
5) central venous O2 saturation (light absorption)
Normal hemodynamics pressure values
RA RV PA PCWP CO PVR
RA = 0-5 mmHg RV = 25/0 mmHg PA = 25/10 mmHg; PA mean = 15-20
PCWP = 5-8 mmHg CO = 5L/min PVR = 1-2 WU
Swan Ganz catheter is floated in a patient and the following tracing is seen. What does this patient have?
A. The pulmonary vascular resistance is increased.
B. Tricuspid valve regurgitation.
C. Pulmonic valve stenosis.
D. Low cardiac output.
Answer = C = pulm valve stenosis
RA = normal RV = pressure incr stays low on the bottom PA = bottom number should incr because one way valve behind you but top number should stay high
in this patient, there is a pressure gradient from RV into pulm artery (because pulm
PRESSURE DROPS FROM RV into PA
IF ANSWER WERE A, YOU WOULD SEE
if pulm vascular resistance there were a drop in diastolic pressure from pulm artery into wedge pressure
PA diastolic pressure should be same as PCWP diastolic pressure
A
A
A
A
A
A
CO may rapidly incr without a ___
significant change in the arterial system
CO incr from 5L/min to 20 L/min
if pulm vasculature resistance is fixed, then you should see___
linear relationship between cardiac output and PA pressure
but pressure incr 1/2 as much
Why does pressure incr as much as expected?
1) high capacitance = more distensible vesels than systemic arteries (7x more distensible)
2) recruitment of unperfused vessels
A dehydrated patient receives an intravenous bolus of fluid. What will happen to the patient’s lung zones?
A. There will be an increase in Zone 1.
B. There will be a decrease in Zone 3.
C. Some Zone 2 lung will become Zone 3.
D. Some Zone 2 lung will become Zone 1
answer = C
dehydrated
so low pressure in pulm vsculature
augment pulm vasculature (incr little bit, incr CO)
some zone 3 that was intemrittently perfused will have continuous blood flow now and become zone 2
additional regulatory mechanisms
hypoxic pulm vasoconstriction
Vasoconstriction in areas with alveolar
hypoxia
– Serves to preserve V/Q matching - very important to survival”
hypoxic pulm vasoconstriction is different from ___
systemic system –> hypoxic vasodilation
not necessary in healthy lungs
a
a
a
a
a
a
normally little blood that enters interstitium leaving capillaries goes into interstitium and then into lymphatics
a
when more fluid leaving capillaries into interstitium
alveoli begin filling up in alveolus
A patient sustains a crush injury of the leg in a car accident, and then 6 hours later develops respiratory failure with this chest x-ray. What will help the patient?
A. Lung protective ventilation.
B. Antibiotics.
C. Diuretics.
D. Pulmonary vasodilators.
noncardiogenic pulm edema = acute respiratory distress syndrome
Answer = A
lung protective ventilation
pulm vessels not narrow
pulm vessels are leaky
A patient in respiratory failure has this chest x-ray. A Swan Ganz catheter is placed and the pulmonary capillary wedge pressure is 20mmHg. What will help this patient?
A. Lung protective ventilation.
B. Antibiotics.
C. Diuretics.
D. Pulmonary vasodilators.
Answer = C
Diuretics because elev pulm capillary wedge pressure
normal wedge = 10
elev PCWP so pulm edema and pressure eev,
