Pulmonary Exam I Flashcards
(108 cards)
1
Q
Majority of resistance to breathing is within the first ____ generations
A
10
- cross sectional area increases farther down the bronchial tree
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)
3
Q
Where is cartilaginous support found in the airway?
A
trachea and subsegmental bronchi (4-9)
4
Q
Conducting Airway Layers
(picture)
A
Ciliated pseudostratified epithelia
5
Q
Cilia
A
propel debris and foreign particles toward glottis
- found in conducting zone
- moves mucus 2cm/min
- works with Nexin
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)
7
Q
Clara Cells
A
secretory in bronchioles and beyond
- conducting zone
- proteins, inflammatory modulators
8
Q
Mast Cells
A
contains inflammatory mediators of conducting zone
- histamine, lyosomal enzymes, met.
9
Q
Bronchial Glands
A
exocrine glands controlled by the parasympathetic NS
10
Q
Respiratory Bronchiole
A
- squamous cell
- some ciliated
- no goblet cells or smooth muscle
- alveoli in walls
11
Q
Alveolar Ducts
A
- walls made of alveoli
- each opens into 10-15 alveoli
12
Q
When do you stop making alveoli?
A
8-10 years old
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
14
Q
Pore of Kohn
A
holes in the walls of adjacent alveoli
- allows air to move between alveoli
15
Q
Type I Alveolar Cells
A
really flat squamous epithelia
- 250 um wide
16
Q
Type II Alveolar Cells
A
manufacture and store sufactant
- contains phospholipids
- decrease surface tension of alveolus
17
Q
Canals of Lambert
A
openings to a second respiratory bronchiole
18
Q
Pathway for Gas Exchange
A
- oxygen inside alveolus
- surfactant
- type I cell (wall)
- basement membrane
- interstital space
- capillary wall (endothelium)
- plasma
- erythrocyte
19
Q
Inhalation
A
expanding chest generates negative pressure
- Diaphragm and external intercostals
20
Q
Accessory muscles of inhalation
A
sternocleidomastoid, scalenes, and pectoralis
21
Q
Muscles of Exhalation
A
abdominals and internal intercostals
22
Q
Pleural space
A
virtual space that contains fluid to reduce friction
- links motion of chest wall and lungs
- negative pressure
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
24
Q
What keeps the chest wall from expanding further?
A
negative pleural pressure
25
Transmural pressure
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
26
End Expiration and During Inspiration
| (pictture)
27
Respiratory compliance
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
28
Normal value of lung compliance
150 mL/cmH2O
(1. 5 k/kPa)
* stiff lungs have a low compliance
29
Compliance curve of lung
| (picture)
30
Factors in elastic recoil of lung
Mainly the surface tension at the alveolar gas-liquid interface
some from tissue elastic forces of lung and chest wall
31
LaPlace's Law
P = 2T/R
32
Pulmonary surfactant
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
33
Surfactant deficiency
decreases compliance of lungs
* needs a greater inflation pressure to keep alveoli open
* areas of atelectasis
* fluid filled alveoli
34
Functional Residual Capacity
when outward expansion of chest wall counter balances the collapsing force of the lungs
* resting equilibrium point
35
Normal value of thoracic cage compliance
200mL/cmH2O
36
FRC as a function of body position
| (picture)
37
FRC in disease states
| (picture)
38
Which generation of bronchi have the highest total resistance?
5th-7th
39
PNS stimulation of bronchial smooth muscle
constriction and secretions
40
What constricts the airway?
* Paraysmpathetic stimulation
* acetylcholine
* histamine
* leukotrienes
* thromboxane A2
* serotonin
* alpha agonists
* decrease PCO2 in small airways
41
What dilates the airway?
* sympathetic stimulation
* Beta receptors
* Beta-2 agonists
* nitric oxide
* increase PCO2 in small airways
* decreased PO2 in small airways
42
Abdominal contraction effects in forced exhalation
* increase:
* intrathoracic pressure
* pleural pressure
* alvevolar pressure
43
Dynamic compression of airway
* amount able to be forced out is **independent of effort**
* increase in pleural pressure is transmitted to airway and alveoli
* flow limitation
44
Flow-Volume Loop
| (picture)
45
Obstructive Diseases
asthma and COPD
* decreased elastic recoil
* reduction in alveolar pressure
* earlier collapse of airways
46
Normal vs. Obstructive flow-volume
| (picture)
Emphysema
47
Spirometry
| (picture)
48
Amount in Lung Volumes and Capacities
* 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
What values cannot be determined with spirometry?
TLC, FRC, and RV
50
Helium Dilution Techinque for Spirometry
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
Pt has circuit volume of 5000ml
Initial concentration of He is 10% in gas
Final concentration of circuit + FRC is 8%
**What is FRC?**
V1C1 = V2C2
(5000 \* 0.10) = (0.08)V2
V2 = 6250mL
FRC = V2 - V1 = 6250 - 5000 = 1250mL
52
Boyle's Law
P1V1 = P2V2
| (at constant temperature)
53
Factors that Influence Dead Space
* 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
Bohr Equation
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
During anesthesia, does the ration of dead space to tidal volume increase or decrease?
increase
56
Alveolar ventilation and CO2 Production
K = arterial partial pressure of CO2
* alveolar ventilation is proportional to CO2 production and inversely proportional to pressure of CO2
57
* transmural pressure is higher at the apex of the lung
* alveoli at apex are less compliant
58
Awake vs. Anesthetized distribution of ventilation in lateral decubitus
Down \> Up when awake
Up \> Down when anesthetized
59
Closing Capacity
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
Closing Capacity and Volume
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
Gas Trapping
occurs when the airway collapses during exhalation and gas becomes trapped behind
* increased FRC and RV
* due to less transmural pressure
62
When closing capacity is higher than FRC
early airway closure and gas not being exchanged
* occurs when supine and anesthetized
63
How can you prevent gas trapping?
CPAP, PEEP, pursed lip breathing
64
Time constant of inflation
Time constant = resistance \* compliance
* time required for inflation of lung if the inital flow rate were maintained
* 1st time constant = 63% inflatted
65
Equal time constants
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
Differing Time Constant
* 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
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)
* 6300
* 5250
* 5600
68
CO from left heart
pulmonary blood flow
6-25 L/min
69
Pulmonary Vascular Resistance (PVR) equation
_PA pressure - left atrial pressure_
CO
70
Zone 1 of the Lung
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
Zone 2 of the Lung
Pa \> Palv \> Pv
* some blood flow because arterial is greater than alveolar but this acts like a Starling resistor
72
Zone 3 of the Lung
Pa \> Pv \> Palv
* flow is determined by arterial-venous pressure difference
* no influence of alveolar pressure
73
Overall pulmonary vascular resistance
solid line is total PVR
* at FRC, pulmonary vascular resistance is minimal
74
Hypoxic Pulmonary Vasoconstriction (HPV)
stimulated by a decrease in PAO2 or mixed venous PO2
* affects primarily small arterioles
* chronic HPV leads to pulmonary hypertension
75
What inhibits HPV
prostacyclin and NO
76
What endothelial mediators increase HPV
thromboxane and endothelin
77
SNS control of PVR
| (adrenergic)
* T1-T5 nerves
* alpha-1 agonism
* vasoconstriction
* Beta-2 agonist
* vasodilation (epi)
78
PNS control of PVR
| (cholinergic)
* vagus
* M3 vasodilation
* Endothelilum and NO dependent
79
Humoral Control of PVR
* Catecholamines
* mostly constriciton
* Prostaglandin, arachidonic acid, leukotrienes, and thromboxane
* vasoconstrictor
* prostacyclin
* vasodilator
* histamine
* vasodilates during Epi constriction
* constricts bronchials
* Serotonin
* constriction
80
Secondary Pulomonary Hypertension
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
Nitric Oxide on Pulmonary Circulation
* pulmonary dilator
* increase V/Q matching
* immunomodulator (decrease inflammation)
* rapidly activated Hb
Side effects:
* short duration
* rebound effect
82
Prostacyclin Derivatives
(epoprostenol, treprostinil, iloprost, cisaprost)
induces relaxation of VSM
* increase production of cAMP
* inhibits growth of smooth-muscle cells
83
ACE inhibitors on Pulmonary Circulation
decrease PVR and vascular remodeling
84
ARBs on Pulmonary Circulation
decrease PAP with no increase in hypoxia
85
Phosphodiesterase inhibitors on Pulmonary Circulation
(amrinon and milrinone)
* slows breakdown of cAMP
* smooth muscle relaxation
86
CCB on Pulmonary Circulation
* relaxation
* may worsen hypoxemia
* large doses often needed to affect pulmonary hypertension
87
Endothelin Antagonists on Pulmonary Circulation
(Ambrisentan)
effective in chronic hypoxia and pulmonary hypertension
88
Pulmonary System Pressures
Right ventricle: 25/0
Pulmonary Artery: 25/8
Pulmonary Catheter: 7mmHg (mean)
Left Atrial: 5mmHg (indirect)
Driving pressure is (PAP - PVP)/LAP
89
typical resting value for alveolar ventilation
4 L/min
90
resting value for pulmonary blood flow
5 L/min
91
Ventilation and Perfusion in Lung
| (picture)
92
Variations in regional alveolar ventilation
(picture)
93
Absolute Shunts
venous blood flow to totally non-ventilated alveoli
Ex: PE or one-lung ventilation
94
Pathological Shunt
tetraology of fallot
| (right to left flow)
95
Capillary Content of Oxygen (CcO2)
CcO2 = (1.31)(Hb)(SAO2) + (0.003\*PAO2)
96
Arterial Oxygen content (CaO2)
CaO2 = (1.31)(Hb)(SaO2) + (0.003\*PaO2)
97
Mixed venous oxygen content (CvO2)
CvO2 = (1.31)(Hb)(SvO2) + (0.003\*PvO2)
98
Partial pressure of Oxygen in the alveolus in ventilated lung
PAO2 = FiO2 \* (Patm - PH2O) - (PaCO2/R)
* PH2O = 47
* R = 0.8
99
Alveolar pressure of Oxygen (PAO2)
PAO2 = PIO2 - (PaCO2/RQ)
100
healthy young patient at rest, what is the correct calculation and result for their partial pressure of oxygen in their alveolus?
(760-47)\*0.21 – 40/0.8
101
Calculating Shunt Fraction (Qs/Qt)
(CcO2 - CaO2) / (CcO2 - CvO2)
102
Patient with a Hb of 15mg/dL, breathing room air at sea level. PAO2 of 100mmHg
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
A-a Difference
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
Assuming normal values for Hb, PCO2 and a-v content difference, the arterial PO2 is determined mainly by \_\_\_\_\_
FiO2
105
MIGET
multiple inert gas elimination technique
* six tracer gases with different solubilities
* retention and elimination are related to solubility coefficient of each tracer
106
V/Q ratios in Disease
| (picture)
COPD Asthma
COPD w/ emphysema After Bronchodilator
107
accessory muscles of inhalation include
sternocleidomastoid, serratus anterior, pec major
108
