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Week 43 > Pulmonary Circulation > Flashcards

Pulmonary Circulation Flashcards

1
Q

what are the 2 sources of blood flow to the lungs?

A
  • Bronchial Circulation
  • Pulmonary Circulation
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2
Q

Bronchial Circulation

A
  • aka Normal Anatomical Shunt
    • 3-4% of total circulation
  • Supplies conducting airways
  • Unoxygenated blood empties into pulmonary vein- Left Atrium
    • PaO2
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3
Q

Pulmonary Artery BP vs Systemic Artery BP

why?

A
  • Pulmonary Artery:
    • MAP=14
    • BP: 24/9
  • Systemic Artery:
    • MAP: 90
    • BP: 120/80
  • Why?
    • Pulmonary Lower bc PVR is 8-10x less than systemic resistance
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4
Q

Pulmonary Vascular Resistance

A
  • 8-10x less than systemic vascular resistance
  • CO(or flow)=MPAP-LAP/PVR
    • MPAP
      • mean pulmonary arterial pressure
      • SBP+(2*DBP)/3
    • LAP
      • Left atrial pressure
    • PVR
      • pulmonary vascular resistance
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5
Q

Measuring Pulmonary BP:

Problems associated

A
  • Catheter entered peripheral vein to:
    • Right Atrium
      • Tricuspid valve
      • Right ventricle emptying
    • Right Ventricle
      • Pulmonic valve
    • Pulmonary Artery
      • Arterial resistance and compliance
      • Capillary resistance and compliance
    • Pulmonary Artery Wedge
      • Left Heart Valve and emptying
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6
Q

Pulmonary Artery wedge

A
  • Mean pressure: 5-7
  • measures pulmonary venous pressure
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7
Q

Regulation of PVR:

A
  • Passive:
    • Vessel Distention and recruitment (pulmonary vessels compliant)
      • CO
      • Pulmonary Artery pressure
      • Gravity-dependent regions
    • Vessels compression
      • lung volume
      • pressures external to blood vessel
    • Blood Viscosity
  • Active: manipulated with drugs
    • Neural
    • Hormonal
    • Endothelial & Inflammatory mediators
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8
Q

Passive Regulation: Distention and Recruitment

A
  • CO increases and maintains:
    • low PVR
    • Low Pulmonary BP
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9
Q

Passive Regulation: Lung volume

A
  • Lowest total PVR @ lung volumes near FRC
    • easiest blood flow occurs b/w breathes
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10
Q

Zones of Lung

A
  • Zones are pressure conditions not anatomic regions
  • Pressure conditions made by:
    • gravity effects on blood flow
    • air distribution
  • Normal Lung: No Zone 1
    • Zone 2:
      • intermittent blood flow
      • due to Pa>PA>Pv
    • Zone 3
      • Constant flow
        • Pa>PA>Pv
  • Zone 1 due to:
    • increased alveolar pressure
      • mechanical ventilation
    • Decreased Cardiac Output
      • Shock
    • Both
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11
Q

Posture effects on Perfusion zones

A
  • If patient has zone 1
    • do not want them upright bc heart needs to generate more pressure to pump blood to apex
    • lay down=lung horizontal
      • no zone 1
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12
Q

Active Regulation of Blood flow:

Vasodilators vs Vasoconstrictors

A
  • Vasoconstrictors
    • Low PAo2
      • hypoxic vasoconstriction
    • High PAco2
    • Sympathetic NE–alpha 1
  • Vasodilators:
    • High PAo2
    • Nitric Oxide
    • Symapthetic:
      • EPI; alpha 2, beta 2 adrenergic
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13
Q

Pulmonary Hypertension affect on lungs

A
  • Can lead to Pulmonary edema and eventually Right Heart Failure
  • causes increased Hydrostatic pressure=Greater net filtration
  • can result in:
    • Interstitium edema
    • Alveolar Filling
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14
Q

Causes of Pulmonary Edema

A
  1. Increased Capillary Hyddrostatic pressure
    1. caused by left heart failure
  2. Decreased capillary colloid osmotic pressure
  3. increased capillary permeability
    1. lung injury
  4. Decreased interstitial pressure
  5. lymphatic insufficiency
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15
Q

Pulmonary edema formation:

Left Atrial pressure

normal range

Safety Factor Range

A
  • Due to:
    • capillary hydrostatic pressure exceeds Oncotic pressure and lymphatic capacity
  • Normal Range:
    • 0-9 Left atrial pressure
  • Safety Factor: 10-25
    • increased lymph flow with increased fluid filtration
    • decreased interstitial oncotic pressure: increased filtration dilutes proteins in interstitial fluid, assumig capillary endothelium is intact
    • high interstitial compliance, but once capacity is reach-alveolar flooding
    • Sufficient surfactant
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16
Q

Airflow

A
  • Ventilation (V)=Pressure Gradient/Resistance
  • depends on:
    • pressure gradient
      • PA-Pb
    • Resistance
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17
Q

Resistance:

A
  • property of conducting airways
  • R=8nL/r^4
  • Radius
    • main determinant of resistance
    • Increase r=Decrease Resistance
    • same in all paralel generations
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18
Q

Factors that affect radius:

A
  • smooth muscle tone
    • does not surround alveoli
  • Lung volume/interdependence
    • @high lung volumes=stretched=pulls out on airways/alveoli=Bigger radius
  • External Pressures
    • if tube is collapsible, Pex can determine flow
    • Depends on location:
      • Extrathoracic: Pb
        • inspiration
      • Intrathoracic, extrapulmonary=Ppl
        • forced expiration
      • Intrathoracic, intrapulmonary
        • Alveolar pressure
        • Lung elastic recoil
  • Patholog conditions
    • Airway wall inflammation (narrow airway)
    • Mucus
    • foreign bodies
    • destroy alveoli walls=no interdependence
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19
Q

Extrathoracic Airways

A
  • Upper trachea, larynx, pharynx, nasal cavity
  • surrounded by tissue
  • 50% of respiratory system resistance
  • all air thru one tube-High Velocity of airflow (Turbulence)
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20
Q

Large Proximal Airways

A
  • Bronchi
  • semi-rigid=cartilage
  • smooth muscle controls diameter(radius)
  • High velocity of airflow (turbulence)
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21
Q

Small Distal Airways

A
  • Bronchioles
  • non-rigid (no cartilage)
  • surrounded by alveoli so stretch of lung and alveolar pressure impact diameter (Radius)
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22
Q

Patterns of Airflow

A
  • Laminar Flow
  • Turbulant flow
  • Transitional Flow
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23
Q

Laminar Flow

A
  • Distal to terminal bronchioles
    • respiratory bronchioles
    • Aleolar ducts
    • Alveoli
  • No turbulence=Sildent Airflow
    • slow velocity
  • R<2000 (Reynolds number)
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24
Q

Turbulent Flow

A
  • Increases resistance
  • requires greater driving pressures and more work
  • R>3000 (reynolds number)
  • Conducting airways
  • MAKE noise
25
Q

Transitional Flow

A
  • What occurs in the lungs
  • occurs in most airways
  • Branching Increases Turbulence
  • R=2000-3000
26
Q

Reynolds number (R)

A
  • predicts turbulence:
27
Q

Turbulence

A
  • Increased by:
    • increased airflow
    • increased individual airway diameter
  • Turbulant flow makes noise
  • Clinically:
    • pt takes deep breathe->Increase airflow and diameter
    • Increase in turbulence
    • Lung sounds easier to heart
    • HELPS detect small airway disease
28
Q

Resistance: Lung Volumes

A
  • Interdependence:
    • Increase Resistance=Decrease Lung Volume
29
Q

Active Control of Airway diameter

A
  • Bronchoconstrictors:
    • Parasympathetic stimulations
    • Acetylcholine—>M3
    • Histamine
    • Decreased Pco2 in small airways
  • Bronchodilators
    • Symapthetic stimulation
    • Epinephrine
    • Beta-2 adrenergic agonists
    • Nitric oxide
    • Decreased Po2 in small airways
    • Increased Pco2 in Small airways

Matches V to Q

  • *
30
Q

Atmosphere AIr: partial Pressures of gases

A
  • N2=78%
  • O2=21%
  • CO2=0.03%
31
Q

Wet Air

A
  • Trachea
  • Ph20=47mmHg @ 37C
    • depends on temp not pressure/altitude
32
Q

Pigas formula

A
  • Pigas=(Pb-Ph20)xFgas
  • Constant=Ph20
  • Change:
    • Pb
    • Fgas=Fraction of O2
33
Q

Ventilation: formula

A
  • VENTILATION=
    • Airflow
      • dP/R
    • Flow rate (L/min)
      • dV/dT
34
Q

What is the driving force for air/gas movement?

A
  • Pressure gradient (dP0
    • PA
    • Pb
35
Q

What variables are important for meeting tissue demands?

A
  • Volume
  • Rate
36
Q

Minute Ventilation formula

A
  • aka total ventilation:
    • Tidal Volume (TV) xFrequency (f)
37
Q

avg Tidal Volume

A

500 ml/breathe

38
Q

Avg frequency:

A

12 breaths/min

39
Q

Alveolar Ventilation: (VA) Formula

A
  • (TV-Dead space Volume (Vd))xfrequency
40
Q

Dead Space Volume

A
  • air that does not participate in gas exchange
  • avg=150mLs
  • can be:
    • anatomical dead space
      • conducting airways
    • pulmonary dead space
      • alveoli that are ventilated but not perfused
41
Q

Physiological Dead space

A
  • Anatomical Dead space+Pulmonary Dead space
  • Bohr Equation:
    • VD/VT=1-(PECO2/Paco2)
42
Q

Avg Alveolar Ventilation:

A

4200mL/min or 4.2L/min

43
Q

Average Total Ventilation

A
  • 6000mL/min or 6 L/min
44
Q

Alveolar Ventilation with gas formula

O2 vs CO2

A
  • VAgas= VA x Figas
  • Resting Alveolaar ventilation w:
    • oxygen=3x what is needed to meet resting metabolic oxygen demand
      • metabolic rate:
        • at rest=0.3 L O2/min
        • Max=3-6 L 02/Min
    • CO2
      • matches what is produced by resting metabolic activity
      • at rest=0.24 L CO2/miin
        • R=0.8
45
Q

Nitrogen Washout

A
  • Measure anatomic dead space NOT physiologic dead space
  • Alveolar Plateau=uniform ventilation
46
Q

Physiologic Dead Space

47
Q

Anatomic Dead Space

A
  • Conducting Airways
  • 150 mLs in 79kg or 2.1mL/kg
  • Normal Anatomic dead space is about 30% of Tidal Volume
48
Q

Pulmonary Deadspace

A
  • aka Alveolar Dead space
  • Alveoli that are ventilated but not perfused
  • Measure=PETCo2-Paco2
    • End Tidal CO2
49
Q

Alveolar O2 Pressure: PAo2

A
  • Function of O2 entering in inspired air and leaving in the blood
  • amount of O2 consumed:
    • PACO2=PaCO2
  • PAO2=Pio2-PaCO2/R
    • R=amount of CO2 produced/Amount of O2 consumed
      • assume 0.8
    • Pio2=150
50
Q

Respiratory Work

A
  • Work=Forcexdistance
    • dPxdV
    • distance=cange in lung volume x breathing rate
  • Inspiratory work
    • force:
      • inspiratory mucles
      • chest wall recoil
  • Expiratory work:
    • force:
      • passive expiration:
        • lung elastic recoil
        • surface tension
      • Forced expiration:
        • expirartor muscle contraction
51
Q

Elastic work vs non-elastic work

A
  • Elastic work
    • Work to overcome elastic recoil of lungs
      • stretch the lungs
    • Increased in restrictive diseases
  • Non-elastic work
    • aka resistive work
    • work to overcome resistance in airway
    • Increase in obstruction diseases
52
Q

Factors that Increase Work of Breathing

A
  • Inspiration:
    • Increase lung elastic recoil
      • elastic work
    • Increase Surface Tension
      • elastic work
    • Increase resistance to airflow
      • non-elastic work
  • Expiration:
    • Increase chest wall recoild
      • elastic
    • Decrease Surface Tension
      • elastic
    • Increase resistance to airflow
      • non-elastic
  • 50% of energy from elastic work during inspiration is stored as PE and used during expiration
    • non-elastic not stored but lost as heat
53
Q

Work of Breathing

A
  • 5% OF TOTAL BODY O2 consumption in normal resting state
54
Q

Effect of Respiratory Rate on Work of Breathing (WOB)

A
  • WOB=elastic work (70%) + non-elastic work (30%)
  • Lowest Total WOB=15 breathes/min
  • non-elastic work:
    • lower at lower respiratory rates
  • elastic work
    • lower at higher respiratory rates
55
Q

Restrictive diseases

A
  • Increases elastic work=Increase total WOB
  • compensate by Increase Respiratory rate
  • Breathe: Fast and shallow
56
Q

Obstructive Diseases

57
Q

V/Q ratios

A
  • Alveolar Ventilation should match Alveolar Perfusion
    • Alveolar Ventilation=4.8 L/min
      • delivers O2
      • removes CO2
    • Alveolar Perfusion=6.0 L/min
      • takes up O2
      • delivers CO2
  • Ideal V/Q ratio=1
    • average=0.8
  • Ventilation and Perfusion is greaters at the base of the lungs
    • greater change in perfusion than ventilationo from apex to base
    • means=V/Q is higher at the apex (top)
      • PO2 high at apex=128>100PAO2
      • PCO2 low at apex=28<40=PACO2
    • Values in upright position
58
Q

Effects of Gravity on V/Q ratio

Week 43 (6 decks)

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