Pulmonary Exam I Flashcards

1
Q

Majority of resistance to breathing is within the first ____ generations

A

10

  • cross sectional area increases farther down the bronchial tree
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2
Q

How many generations make up the conducting zone?

A

0-16

  • starts from the trachea (0) and ends at the terminal bronchioles (16)
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3
Q

Where is cartilaginous support found in the airway?

A

trachea and subsegmental bronchi (4-9)

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4
Q

Conducting Airway Layers

(picture)

A

Ciliated pseudostratified epithelia

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5
Q

Cilia

A

propel debris and foreign particles toward glottis

  • found in conducting zone
  • moves mucus 2cm/min
  • works with Nexin
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6
Q

Goblet Cells

A

produce mucus in conducting zone

  • 100 mL of mucus a day
  • viscoelastic
    • deforms and spread when force is applied to it
  • innervated by parasympathetic NS (Vagus)
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7
Q

Clara Cells

A

secretory in bronchioles and beyond

  • conducting zone
  • proteins, inflammatory modulators
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8
Q

Mast Cells

A

contains inflammatory mediators of conducting zone

  • histamine, lyosomal enzymes, met.
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9
Q

Bronchial Glands

A

exocrine glands controlled by the parasympathetic NS

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10
Q

Respiratory Bronchiole

A
  • squamous cell
    • some ciliated
  • no goblet cells or smooth muscle
  • alveoli in walls
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11
Q

Alveolar Ducts

A
  • walls made of alveoli
  • each opens into 10-15 alveoli
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12
Q

When do you stop making alveoli?

A

8-10 years old

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13
Q

Approximately how many alveoli are in an adult?

A

300 million

  • up to 280 billion pulmonary capillaries
  • SA for gas exchange is about 70m2
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14
Q

Pore of Kohn

A

holes in the walls of adjacent alveoli

  • allows air to move between alveoli
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15
Q

Type I Alveolar Cells

A

really flat squamous epithelia

  • 250 um wide
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16
Q

Type II Alveolar Cells

A

manufacture and store sufactant

  • contains phospholipids
  • decrease surface tension of alveolus
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17
Q

Canals of Lambert

A

openings to a second respiratory bronchiole

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18
Q

Pathway for Gas Exchange

A
  • oxygen inside alveolus
  • surfactant
  • type I cell (wall)
  • basement membrane
  • interstital space
  • capillary wall (endothelium)
  • plasma
  • erythrocyte
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19
Q

Inhalation

A

expanding chest generates negative pressure

  • Diaphragm and external intercostals
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20
Q

Accessory muscles of inhalation

A

sternocleidomastoid, scalenes, and pectoralis

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21
Q

Muscles of Exhalation

A

abdominals and internal intercostals

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22
Q

Pleural space

A

virtual space that contains fluid to reduce friction

  • links motion of chest wall and lungs
  • negative pressure
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23
Q

Resting position of chest wall

A

negative intrathoracic pressure is required to keep it from expanding to its resting position

  • usually greater than its dimensions in vivo
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24
Q

What keeps the chest wall from expanding further?

A

negative pleural pressure

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25
Q

Transmural pressure

A

unequal pressures on either side of structure define expanion or compression

Pinside - Poutside

  • positive: forces that expand of increase volume
  • negative: collapsing forces or decrease volume
  • zero value: unstressed, resting position
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26
Q

End Expiration and During Inspiration

(pictture)

A
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27
Q

Respiratory compliance

A

lung and thoracic cage are in series

1/total = 1/lung + 1/chest wall

  • for a supine paralyzed patient:
    • 1/0.85 = 1/1.5 + 1/2
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28
Q

Normal value of lung compliance

A

150 mL/cmH2O

(1. 5 k/kPa)
* stiff lungs have a low compliance

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29
Q

Compliance curve of lung

(picture)

A
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30
Q

Factors in elastic recoil of lung

A

Mainly the surface tension at the alveolar gas-liquid interface

some from tissue elastic forces of lung and chest wall

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31
Q

LaPlace’s Law

A

P = 2T/R

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32
Q

Pulmonary surfactant

A

produced by type II and stored in lamellar bodies

  • 90% lipids
    • 10% proteins
    • albumin and globulin
    • 2% surfactant proteins
  • Mono or multi- layer structure
  • 5-30 dynes/cm
    • compaired to 72 in water
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33
Q

Surfactant deficiency

A

decreases compliance of lungs

  • needs a greater inflation pressure to keep alveoli open
  • areas of atelectasis
  • fluid filled alveoli
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34
Q

Functional Residual Capacity

A

when outward expansion of chest wall counter balances the collapsing force of the lungs

  • resting equilibrium point
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35
Q

Normal value of thoracic cage compliance

A

200mL/cmH2O

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36
Q

FRC as a function of body position

(picture)

A
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37
Q

FRC in disease states

(picture)

A
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38
Q

Which generation of bronchi have the highest total resistance?

A

5th-7th

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39
Q

PNS stimulation of bronchial smooth muscle

A

constriction and secretions

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40
Q

What constricts the airway?

A
  • Paraysmpathetic stimulation
  • acetylcholine
  • histamine
  • leukotrienes
  • thromboxane A2
  • serotonin
  • alpha agonists
  • decrease PCO2 in small airways
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41
Q

What dilates the airway?

A
  • sympathetic stimulation
    • Beta receptors
  • Beta-2 agonists
  • nitric oxide
  • increase PCO2 in small airways
  • decreased PO2 in small airways
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42
Q

Abdominal contraction effects in forced exhalation

A
  • increase:
    • intrathoracic pressure
    • pleural pressure
    • alvevolar pressure
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43
Q

Dynamic compression of airway

A
  • amount able to be forced out is independent of effort
  • increase in pleural pressure is transmitted to airway and alveoli
    • flow limitation
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44
Q

Flow-Volume Loop

(picture)

A
45
Q

Obstructive Diseases

A

asthma and COPD

  • decreased elastic recoil
  • reduction in alveolar pressure
  • earlier collapse of airways
46
Q

Normal vs. Obstructive flow-volume

(picture)

A

Emphysema

47
Q

Spirometry

(picture)

A
48
Q

Amount in Lung Volumes and Capacities

A
  • Total Lung Capacity
    • 6.0L
  • Inspiratory Capacity
    • 3.0L
  • Functional Residual Capacity
    • 3.0L
  • Inspiratory Reserve Volume
    • 2.5L
  • Tidal Volume
    • 0.5L
  • Expiratory Reserve Volume
    • 1.5L
  • Residual Volume
    • 1.5L
  • Vital Capacity
    • 4.5L
49
Q

What values cannot be determined with spirometry?

A

TLC, FRC, and RV

50
Q

Helium Dilution Techinque for Spirometry

A

C1V1 = C2V2

FRC = V2 - V1

  • helilum is not absobed into the blood so it stays in the alveoli
  • underestimated number bevause it only measures central airways
51
Q

Pt has circuit volume of 5000ml

Initial concentration of He is 10% in gas

Final concentration of circuit + FRC is 8%

What is FRC?

A

V1C1 = V2C2

(5000 * 0.10) = (0.08)V2

V2 = 6250mL

FRC = V2 - V1 = 6250 - 5000 = 1250mL

52
Q

Boyle’s Law

A

P1V1 = P2V2

(at constant temperature)

53
Q

Factors that Influence Dead Space

A
  • Size
  • Age
    • Neonate (3.3mL/kg)
    • adult (2mL/kg)
  • Posture
    • sitting > supine
  • Neck/jaw position
    • extended > flexed
  • Lung volume
    • higher volume = more dead space
  • Tracheal intubation
    • eliminates 1/2 but adds apparatus, so often the same
  • Tidal Volume and RR
    • decrease tidal volume decreases deadspace due to laminar flow
    • decreased RR decreases deadspace
54
Q

Bohr Equation

A

Ratio of dead space to total tidal volume

VD/VT = (PaCO2 - PECPO2) / PaCO2

  • VD/VT is usually around 0.3
  • VA = (VT - VD) * RR
55
Q

During anesthesia, does the ration of dead space to tidal volume increase or decrease?

A

increase

56
Q

Alveolar ventilation and CO2 Production

A

K = arterial partial pressure of CO2

  • alveolar ventilation is proportional to CO2 production and inversely proportional to pressure of CO2
57
Q
A
  • transmural pressure is higher at the apex of the lung
  • alveoli at apex are less compliant
58
Q

Awake vs. Anesthetized distribution of ventilation in lateral decubitus

A

Down > Up when awake

Up > Down when anesthetized

59
Q

Closing Capacity

A

closing volume + residual volume

  • independent of body position
  • When FRC is less than closing capacity, some of the pulmonary blood will be distributed to alveoli with closed airways, usually in the dependent part of the lung, which will constitute a shunt and will increase the P(A-a) gradient
60
Q

Closing Capacity and Volume

A

Closing capacity occurs when dependent airways begin to close as lung volume decreases

  • closing capacity increases with age
    • pleural pressure is becoming less negative
61
Q

Gas Trapping

A

occurs when the airway collapses during exhalation and gas becomes trapped behind

  • increased FRC and RV
  • due to less transmural pressure
62
Q

When closing capacity is higher than FRC

A

early airway closure and gas not being exchanged

  • occurs when supine and anesthetized
63
Q

How can you prevent gas trapping?

A

CPAP, PEEP, pursed lip breathing

64
Q

Time constant of inflation

A

Time constant = resistance * compliance

  • time required for inflation of lung if the inital flow rate were maintained
  • 1st time constant = 63% inflatted
65
Q

Equal time constants

A

pressure build up will be identical during inflation

  • distribution of ventilation is not dependent on rate, duration, or frequency
  • NO redistribution of gas

Ex: flat expiratory waveform

(although not necessarily uniform ventilation)

66
Q

Differing Time Constant

A
  • distribution of ventilation depends on rate, duration, and frequency
  • dynmaic compliance is decreased with increasing frequency
  • Redistribution of gas occurs

Ex: upsloping EtCO2 waveform

67
Q

Vd/Vt calculations for a 70kg patient

  • 600mL breaths * 15 RR
  • 300mL breaths * 25 RR
  • 1000mL breaths * 8 RR

Calculate minute ventilation and alveolar ventilation

(assume a normal Vd/Vt ratio of 0.3)

A
  • 6300
  • 5250
  • 5600
68
Q

CO from left heart

A

pulmonary blood flow

6-25 L/min

69
Q

Pulmonary Vascular Resistance (PVR) equation

A

PA pressure - left atrial pressure

CO

70
Q

Zone 1 of the Lung

A

Palv > Pa > Pv

  • apex of the lung
  • little to no flow of blood to this regin
  • capillaries are flattened by pressure in alveolus
  • does not occur in normal conditions
71
Q

Zone 2 of the Lung

A

Pa > Palv > Pv

  • some blood flow because arterial is greater than alveolar but this acts like a Starling resistor
72
Q

Zone 3 of the Lung

A

Pa > Pv > Palv

  • flow is determined by arterial-venous pressure difference
  • no influence of alveolar pressure
73
Q

Overall pulmonary vascular resistance

A

solid line is total PVR

  • at FRC, pulmonary vascular resistance is minimal
74
Q

Hypoxic Pulmonary Vasoconstriction (HPV)

A

stimulated by a decrease in PAO2 or mixed venous PO2

  • affects primarily small arterioles
  • chronic HPV leads to pulmonary hypertension
75
Q

What inhibits HPV

A

prostacyclin and NO

76
Q

What endothelial mediators increase HPV

A

thromboxane and endothelin

77
Q

SNS control of PVR

(adrenergic)

A
  • T1-T5 nerves
  • alpha-1 agonism
    • vasoconstriction
  • Beta-2 agonist
    • vasodilation (epi)
78
Q

PNS control of PVR

(cholinergic)

A
  • vagus
  • M3 vasodilation
    • Endothelilum and NO dependent
79
Q

Humoral Control of PVR

A
  • Catecholamines
    • mostly constriciton
  • Prostaglandin, arachidonic acid, leukotrienes, and thromboxane
    • vasoconstrictor
  • prostacyclin
    • vasodilator
  • histamine
    • vasodilates during Epi constriction
    • constricts bronchials
  • Serotonin
    • constriction
80
Q

Secondary Pulomonary Hypertension

A

due to chronic hypodia or lung disease

  • leads to right sided heart failure
  • hard to treat
    • non-specificity of pulmonary receptors
    • drugs that treat increased PVR may abolish HPV
81
Q

Nitric Oxide on Pulmonary Circulation

A
  • pulmonary dilator
  • increase V/Q matching
  • immunomodulator (decrease inflammation)
  • rapidly activated Hb

Side effects:

  • short duration
  • rebound effect
82
Q

Prostacyclin Derivatives

(epoprostenol, treprostinil, iloprost, cisaprost)

A

induces relaxation of VSM

  • increase production of cAMP
  • inhibits growth of smooth-muscle cells
83
Q

ACE inhibitors on Pulmonary Circulation

A

decrease PVR and vascular remodeling

84
Q

ARBs on Pulmonary Circulation

A

decrease PAP with no increase in hypoxia

85
Q

Phosphodiesterase inhibitors on Pulmonary Circulation

(amrinon and milrinone)

A
  • slows breakdown of cAMP
  • smooth muscle relaxation
86
Q

CCB on Pulmonary Circulation

A
  • relaxation
  • may worsen hypoxemia
  • large doses often needed to affect pulmonary hypertension
87
Q

Endothelin Antagonists on Pulmonary Circulation

(Ambrisentan)

A

effective in chronic hypoxia and pulmonary hypertension

88
Q

Pulmonary System Pressures

A

Right ventricle: 25/0

Pulmonary Artery: 25/8

Pulmonary Catheter: 7mmHg (mean)

Left Atrial: 5mmHg (indirect)

Driving pressure is (PAP - PVP)/LAP

89
Q

typical resting value for alveolar ventilation

A

4 L/min

90
Q

resting value for pulmonary blood flow

A

5 L/min

91
Q

Ventilation and Perfusion in Lung

(picture)

A
92
Q

Variations in regional alveolar ventilation

(picture)

A
93
Q

Absolute Shunts

A

venous blood flow to totally non-ventilated alveoli

Ex: PE or one-lung ventilation

94
Q

Pathological Shunt

A

tetraology of fallot

(right to left flow)

95
Q

Capillary Content of Oxygen (CcO2)

A

CcO2 = (1.31)(Hb)(SAO2) + (0.003*PAO2)

96
Q

Arterial Oxygen content (CaO2)

A

CaO2 = (1.31)(Hb)(SaO2) + (0.003*PaO2)

97
Q

Mixed venous oxygen content (CvO2)

A

CvO2 = (1.31)(Hb)(SvO2) + (0.003*PvO2)

98
Q

Partial pressure of Oxygen in the alveolus in ventilated lung

A

PAO2 = FiO2 * (Patm - PH2O) - (PaCO2/R)

  • PH2O = 47
  • R = 0.8
99
Q

Alveolar pressure of Oxygen (PAO2)

A

PAO2 = PIO2 - (PaCO2/RQ)

100
Q

healthy young patient at rest, what is the correct calculation and result for their partial pressure of oxygen in their alveolus?

A

(760-47)*0.21 – 40/0.8

101
Q

Calculating Shunt Fraction (Qs/Qt)

A

(CcO2 - CaO2) / (CcO2 - CvO2)

102
Q

Patient with a Hb of 15mg/dL, breathing room air at sea level. PAO2 of 100mmHg

A

CcO2 = (1.31)(15)(1.0) +( .003)(100)=20 ml/dL

CaO2 = (1.31)(15)(.90) + (.003)(90)= 17.87 ml/dL

CvO2 = (1.31)(15)(.75)+(.003)(40)= 14.86 ml/dL

Qs/Qt = 20 – 17.87 / 20 – 14.86 = 41.44% shunt fraction

103
Q

A-a Difference

A

alveolar to arterial oxygen partial pressure difference

PAO2 - PaO2

  • increases in A-a difference is due to problems with gas exchange
    • V/Q mismatch
    • True shunt
104
Q

Assuming normal values for Hb, PCO2 and a-v content difference, the arterial PO2 is determined mainly by _____

A

FiO2

105
Q

MIGET

A

multiple inert gas elimination technique

  • six tracer gases with different solubilities
  • retention and elimination are related to solubility coefficient of each tracer
106
Q

V/Q ratios in Disease

(picture)

A

COPD Asthma

COPD w/ emphysema After Bronchodilator

107
Q

accessory muscles of inhalation include

A

sternocleidomastoid, serratus anterior, pec major

108
Q
A