Pulmonary circulation Flashcards
(blank) enter each lung at the hilum, they
travels adjacent to, and branches with each airway generation, to respiratory bronchiole
pulmonary arteries
(blank) carry oxygenated blood from the lungs to the left atrium.
(blank) pulmonary veins pass behind the right atrium and superior vena cava
(blank) pulmonary veins pass in front of descending thoracic aorta
pulmonary veins
Right
left
(blank) are the primary site of gas exchange
directly opposed to the alveoli and 0.6 microns thick
pulmonary capillaries
blood pressure varies with the (blank) of lung. What is it at the apex? What is it at the base?
height
(24 mm Hg at FRC) apex = 12 mm Hg, base = 36 mm Hg
Normal Pulmonary Artery Pressure (PPA) is (blank) (PA systolic 15/PA diastolic 8 mm Hg). Where is this value measured?
15 mm Hg
at main pulmonary artery
Pulmonary circulation is a (blank)-pressure circuit. 35-45%of pulmonary vascular resistance (PVR) is at the level of the (blank)
capillaries
low pre-capillary arterial resistance results in (blank) motion in the microvascular bed. When is this motion lost?
pulsatile
In severe pulmonary arterial hypertension (PAH)
How long is the transit time across the microcirculation and what does this amount of time allow for?
.5-1 second and allows for enough to for O2 and CO2 tensions in alveoli (partial pressure) to equilibrate
The pulmonary vascular resistance is (blank) of the systemic vascular resistance.
1/10th
What is the equation for pulmonary vascular resistance?
change in pressure divided by pulmonary blood flow
PPA(arterial) - PPV(venous) / Pulmonary Blood Flow
Pulmonary vascular resistance depends on capillary resistance, the change in pressure and blood flow and on (blank) pressures.
left atrial pressures
As Left atrial pressure (PLA) increases, pulmonary vascular resistance will (blank), because the vascular bed is (blank).
stop decreasing
nearly fully distended
The capillaries are near (blank) pressure because of surfactant.
atmospheric
If alveolar pressure is greater than capillary pressure, then capillaries (blank).
collapse
When the lungs expand (inspiration), what happens to pressure?
your pressure decreases causing radial traction
What does radial traction do?
it pulls open vessels, and reduces pressure
What are the three things that reduce pulmonary vascular resistance?
recruitment (opening of closed capillaries)
Distention (increase caliber of already open capillaries)
Expansion of lung volume
What is the typical distribution of blood flow?
When is this not true?
basal blood flow is greater than apical blood flow
If a human is upside down (it is opposite)
What is the reason for regional blood flow differences?
hydrostatic pressure
At the apex of the lung (zone 1), what is happening with it?What are happening to the capillaries at the apex of the lung?
- > the apex is ventilated but not perfused
- > dead space and you have increased CO2 here. ->collapse of vessel before it crosses alveolus; no forward flow; doesn’t exist in normal lungs – might occur if person has hemorrhaged (BP, intravascular volume are low)
- > capillaries are flattened due to increase Palveolar, except for extra-alveolar capillaries which are patent
What kind of zone will you have if you are hemmoraging?
Zone 1-> capillaries collapse due to increase alveolar pressure
PALV >PPA>PPV
At the middle of the lung (zone 2), how is blood flow determined?
it is the difference between Palveolar & Parterial. Arterial is greater, causing great distension and increased blood flow.
What has the highest pressure at midlung (zone 2), the PPA, PALV or PPV?
PPA > PALV > PPV
Which zone has the waterfall effect?
Zone 2 (midlung)
What is a pulmonary artery wedge pressure?
utilizes swan-ganz catheter inserted into pulmonary circulation to measure static fluid pressure and reflects left atrial pressure and estimates total body fluid balance.
What is this and what is it’s normal value?
Swan-Ganz catheter inserted into pulmonary circulation measures static fluid pressure in pulmonary circuit reflects left atrial pressure and estimates total body fluid balance
Pulmonary Artery Wedge Pressure
8-12 mm Hg
Which part of the lung gets less blood flow, the apex or base?
apex
The pressure in the arterial is always going to be higher than the pressure in what?
the vein
If you are in the supine position what happens to your blood flow?
increased apical blood flow
same basal blood flow
If you are undergoing mild exercise what happens to your apical and basal blood flow?
increased apical and basal blood flow (decreased regional differences)
What zone will you be in if you are exercising?
zone 2 (waterfall effect) PPA > PALV > PPV
Where does zone 3 occur and what is it?
occurs basally, it is the blood flow determined by usual arterial-venous difference PPA > PPV > PALV
What is hypoxic vasoconstriction?
when you get contraction of arteriolar smooth muscle walls in hypoxic region and directs blood to less hypoxic regions
(blank) is an endothelial derived releasing factor that causes smooth muscle relaxation
NOx
What is formed from L-Arginine via guanylate cyclase, forming cyclic GMP?
NOx
Active control of circulation has the greatest responsiveness at a pO2 of what?
less than 70 mm Hg
What is salvage therapy?
a last effort to reduce pulmonary hypoxic vasoconstriction via NOx
High altitude generally causes (blank) and increased (blank)
vasoconstriction and increased arterial pressure
A fetus has increased (blank) resulting in only 15% of Cardiac output to lungs. When they take their first breath, you will get decreased (blank) and increased pulmonary blood flow
Pulmonary vascular resistance (PVR)
PVR
What are these:
carbon monoxide, increased PVR, hypothermia, acidosis and alkalosis, inhaled anesthetics, Ca blockers, postive end-expiratory pressure, high frequency ventilation, isproterenol, vasodilators
Factors that inhibit hypoxic vasoconstriction
Pulmonary capillaries follow (blank) law
starlings’s
Net Fluid = K[(PC-Pi) - ∂ (∏C-∏P)]
Fluid leakage from capillaries goes to (blank) of alveolar walls via perivascular and peribronchial lymph nodes
interstitium
Fluid leakage from capillaries goes into the interstitium of alveolar walls via perivascular and peribronchial lymph nodes. This can cause (blank) because of the excess fluid in the hilar lymph nodes. When might this occur?
interstitial edema
CHF
(blank) occurs when capacity of the lymphatics is exceeded and fluid pours into alveoli which interferes with gas exchange
alveolar edema
(blank) causes an increase in intracranial pressure. This leads to an increase in pulmonary capillary pressure, this can cause trauma to capillaries and increased capillary permeability
neurogenic pulmonary edema
What can be caused by increased sympathetic discharge resulting in increased pulmonary capillary pressure?
neurogenic pulmonary edema
What type of edema causes hypoxia-induced vasoconstriction at pre-capillary sites but the mechanism for its cause is still unknown?
high-altitude pulmonary edema
What causes this:
accumulation of proteinaceous fluid in the alveoli due to a number of causes
causes significant Ventilation-Perfusion (V-Q) mismatch
Adult Respiratory Distress Syndrome (ARDS)
What are the causes of ARDS?
severe trauma, sepsis, pancreatitis, aspiration pneumonia, community-acquired pneumonia
How do you treat ARDS?
with low tidal volume ventilation
(Don’t want too much volume or pressure-> will rupture alveoli and collapse them, may make a pneumothorax. SOOOO lets prevent this by making pnt have low tidal volume)
What does this describe? 60-70% mortality at 30-days lower in trauma victims tend to be younger and healthier higher in alcohol abusers
ARDS
What is Transfusion-Related Acute Lung Injury (TRALI)
Variant of ARDS, occurs with massive blood transfusion (mostly with fresh plasma)
What causes TRALI?
Granulocytes from a blood transfusion will cause an inflammation reaction in pulmonary capillaries where your antibodies attack the new blood you just got. (not too bad,just lasts a few days)
What does this describe? develops within 1-2 hours of transfusion fever, tachycardia, tachypnea development of pink, frothy sputum patients usually extubated within 48h
TRALI
What are two interesting functions of the pulmonary circulation?
reservoir for blood due to low PVR
Filtration (small thrombi, and WBC’s)
The lung functions metabolically by activating (blank)
angiotensin I to angiotensin II via ACE
Where is ace found?
small pits of capillary endothelial cells of lung
What does the lung inactivate?
bradykinin (via ACE, up to 80% of it) Serotonin (via uptake and storage) Prostaglandin (E1 /E2/F2∝ (removed) Norepinephrine (up to 30%) Arachidonic acid
When does the lung release serotonin?
during anaphylaxis, to transfer to platelets in lung
What does the lung do to arachidonic acid?
converts it to leukotrienes (via lipoxygenase)
and to prostaglandins (via cyclooxygenase)
What does prostaglandin E2 do?
relaxes patent ductus arteriosus in fetus
What do all prostaglandins cause?
platelet aggregation and bronchoconstriction in asthma
What does the lung synthesize?
surfactant
proteins
mucopolysaccharides (bronchial mucus)
What kind of proteins does the lung synthesize?
collagen and elastic of lung framework (broken down by protease)
What blocks protease?
antitrypsin : )
What is transmural pressure?
inside of vessel minus outside of vessel (why the capillaries collapse due to large Palveolar)
What regulates blood flow and resistance in the pulmonary circuit?!?!?!
CAPILLARIES
