1
Q
What does P IP & P PL stand for?
A
Pleural Pressure
2
Q
- What does P A stand for?
A
Alveolar pressure
3
Q
- What does P EL & P ER stand for?
A
Elastic recoil pressure
4
Q
- What does P TP stand for?
A
Transpulmonary pressure
5
Q
- What is the normal pleural pressure & when is it measured?
A
-5 cm H2O & measured in between breaths
6
Q
- What is the normal P A pressure?
A
- 0 cm H2O
- It oscillates between -1(inspiration) & +1(expiration) cm H2O
7
Q
- What does P EL refer to & what is its normal pressure?
A
- It refers to stretched out lung wanting to recoil
- The pressure is +5 cm H2O (equal & opposite to intrathoracic pressure)
8
Q
- What is the formula for Transpulmonary pressure?
A
P TP= P A – P IP
9
Q
- What does transmural pressure refer to?
A
Pressure available to fill up the lungs
10
Q
What does a (+) transmural pressure indicate?
A
Availability to put air into the lungs
11
Q
What is the chest wall’s normal resting tone?
A
Outward
12
Q
What do the following letters stand for; C, a, A, V, D?
A
- C= Content
- a= arterial
- A= Alveolar
- V= Ventilation per min
- D= Gas absorbed/expired per min
13
Q
How much oxygen (mg) does 1 dL have?
A
20mg
14
Q
What is the formula for compliance?
A
Compliance= Delta V / Delta P
15
Q
What is the formula for Elastance?
A
Elastance= Delta P / Delta V
16
Q
When is someone’s peak lung function?
A
At age 20
17
Q
What is the normal VT?
A
500mL
18
Q
What is the normal FRC?
A
Normal functional residual capacity is 3.0L
19
Q
What volume or capacity helps keep the lungs from collapse?
A
RV
20
Q
What makes up the FRC?
A
ERV= 1.5 L & RV= 1.5 L
21
Q
What is the lung volume at the end of maximal expiration?
A
1.5L only the RV is left
22
Q
What is used as a buffer when we do not breath for a bit but already exhaled?
A
RV
23
Q
What is the total lung capacity (TLC)?
A
6.0 L
24
Q
What makes up Vital capacity (VC)?
A
- IRV= 2.5 L,
- VT= 0.5 L
- ERV= 1.5 L
25
What is the max IRV?
2.5 L
26
In the supine position, which lung volume(s) do not change?
RV, VT
27
In the supine position, which volume(s) decrease?
ERV, FRC
28
In the supine position, which volume(s) increase?
IRV
29
How long is the normal breathing cycle?
5sec total
- Inspiration= 2sec
- expiration= 2sec
- 1 sec in between
30
What changes does the PA undergo during expiration?
PA goes to +1 cm H2O at 1sec then back to 0 @ the end of expiration
31
What is the P ER at the end of inspiration?
-7.5 cm H2O
32
When is the max inspiratory Delta P for the alveoli?
It is @ 1sec of the inspiratory cycle. PA pressure is @ -1 cm H2O
33
What makes up the PVR?
Alveolar & Extraalveolar BV’s
34
How does lower lung volumes affect PVR?
There is a higher increase in Extraalveolar resistance than decrease in Alveolar resistance resulting in a higher PVR
35
How does higher lung volumes affect PVR?
There is a small decrease in Extraalveolar resistance & big increase in Alveolar resistance resulting in a higher PVR.
36
Does an increase or decrease in lung volume lead to a higher PVR?
Decrease
37
What happens to alveolar capillaries during inspiration?
They increase in length & decrease in diameter --> higher resistance
38
What happens to Extraalveolar vessels during inspiration?
The negative pressure pulls on the vessel walls increasing diameter & decreasing resistance.
39
How much dead space volume is there?
150 mL
40
What is the normal RR?
12 bpm
41
What does V E stand for?
Total minute ventilation
42
What do most pulmonary tests look at?
At expired air
43
What action is the better option to increase O2 saturation?
Increase depth of breath rather than RR
44
What is the formula for calculating tidal volume?
VT= VDS + VA
45
Where is the apex of the lung?
It extends superior passed the 1st rib
46
Where is the most movement of the lungs & how much is it?
At the base & it’s about 2cm
47
What seals the thorax & abdomen?
The central tendon
48
What are the 3 diaphragm openings, anterior to posterior?
- Caval aperture
- Esophageal aperture
- aortic aperture
49
What is the caval aperture?
Opening for the inferior vena cava
50
What nerve is connected to the diaphragm?
The L & R phrenic nerves
51
What prevents inferior thorax movement during inspiration?
The scalene muscles
52
The anterior scalene muscle connects to what structures?
The 1st rib & to C3 - C6
53
The middle scalene muscle connects to what structures?
The 1st rib & to C3 – C7
54
The posterior scalene muscle connects to what structures?
The 2nd rib & to C5 – C7
55
What structures make up the dead space?
- Trachea
- Bronchi
- Bronchioles
- Terminal bronchioles
56
What structures play part in actual air exchange?
- Respiratory bronchioles
- alveolar ducts
- alveolar sacs
57
How many generations does the conducting zone have?
16 generations
58
How many generations does the respiratory zone have?
7 generations
17 - 23
59
What is stridor?
Noise from an obstruction in the airway
60
What is hyperpnea?
Hyperventilation in excess of metabolic needs
61
What is orthopnea?
Body position changes cause difficulty breathing
62
What is the difference between looking blue & looking grey?
- Blue means the Hgb does not have O2 attached.
- Grey means Hgb is low.
63
At what point does cyanosis occur?
When Deoxy Hgb is > 5 gm/dL
64
What is hypoxia?
Decreased O2 amount at tissue level
65
What is hypoxemia?
Decreased O2 in arterial blood
66
What is hyper/hypocapnia?
Excessive/deficiency of CO2 in arterial blood
67
Air passes through the nose or mouth, to the___, and then to the___ and then into the tracheobronchial tree.
Pharynx & larynx
68
What constitutes the transitional zone?
Generations 17-19, the respiratory bronchioles
69
What all entails an acinus?
An acinus includes respiratory bronchiole, alveolar ducts & alveolar sacs distal to a single terminal bronchiole
70
What are the air pathway structures after the larynx to gas exchange?
Trachea ->
bronchi ->
bronchioles ->
terminal bronchioles ->
respiratory bronchioles ->
alveolar ducts ->
alveolar sacs
71
What is the structural difference from bronchi and bronchioles?
Bronchioles do not contain cartilage.
72
Clara cells secrete what?
- Proteins (SpA, B, C & D)
- lipids
- glycoproteins
- inflammatory modulator
73
What are the other functions of Clara cells?
- Metabolize foreign materials
- participate in airway fluid balance
- act as progenitor cells
74
About how many alveoli are in a healthy human being?
~ 480 billion
75
What allows for interalveolar communications?
The pores of Kohn
76
What is the ratio of Type I to Type II cells?
1:2
77
Type I cells cover about___% of the alveolar surface due to__?
90-95% Due to the larger surface area
78
What are the purposes of Type I cells?
- They allow for easy gas exchange
- Help remove liquid from the alveolar surface by pumping sodium & water into the interstitium.
79
What generates spontaneous automatic breathing?
Neurons located in the medulla
80
What causes the resting negative intrathoracic pressure?
The mechanical interaction in opposite directions between the lung and chest wall
81
What is contained in the intrapleural space?
About 15-25mL of a serous liquid
82
During inspiration the transmural pressure difference___ & the alveoli are distended, ___ alveolar pressure?
Increases & Decreasing
83
Alveolar pressure is equal to intrapleural pressure + _____?
Alveolar elastic recoil pressure
84
What establishes the pressure gradient for air flow?
Increasing alveolar volume lowers alveolar pressure
85
What mechanically transmits the pressure difference across alveoli?
The alveolar septa
86
What are the accessory inspiratory muscles & when are they involved?
- The sternocleidmastoid, the trapezius, & vertebral column muscles.
- They are involved during exercise, coughing, sneezing or pathologic state such as asthma
87
The diaphragm is considered part of the___?
Chest wall
88
When supine the diaphragm is responsible for ___ of the air entering during eupnea? What about standing?
- Supine is 2/3 &
- Standing is 1/3
89
The diaphragm is innervated by the ____, which leave the spinal cord at the __ thru the ___ cervical segments?
- Phrenic nerves
- 3rd & 5th
90
What holds the diaphragm to the lower 6 ribs & the sternum?
By 2 crura
91
During eupnea the diaphragm descends __ cm & during deep breathing is descends __ cm?
1-2cm & 10cm
92
The scalene muscles are accessory muscles?
False, they contract during eupnea, therefore are not accessory muscles
93
What muscles contract during normal expiration?
None, expiration is passive
94
In obese people the inspiratory muscle may also contract, when?
During early part of expiration
95
When does active expiration occur?
During exercise, speech, signing, sneezing, coughing, bronchitis.
96
Contraction of the internal intercostal muscles move the ribcage___?
Downward, opposite of the external intercostals
97
What is the I:E ration in eupnea?
1:2 or 1:4
98
During inspiration the alveolar pressures ___?
Decrease (-1 cm H2O)
99
Compliance is the inverse of ____?
Elastance
100
Elastance refers to?
Tendency for something to oppose stretch & its ability to return to its original state.
101
Surfactant has a lesser effect on surface tension during___ due to?
- Inspiration.
- Due to movement of surfactant from interior of the liquid phase to the surface during inspiration.
102
Many pathologic states shift the compliance curve to the___?
Right ( for any increase in transpulmonary pressure there is less of an increase in lung volume)
103
Fibrosis, atelectasis & thermal injuries ___ alveolar elastic recoil?
Increase. Fibrosis decreases compliance, therefore elastance is increased
104
Emphysema ___ compliance due to the destruction of the ___ tissue?
- Increases
- septal tissue, which opposes lung expansion.
105
Compliance in obese people is ___?
- Decreased.
- Moving the diaphragm downward is much more difficult
106
Abdominal distension & scars from burn injuries cause ___ chest wall compliance?
Decreased
107
How does someone with emphysema compensate?
With a greater RR & smaller Vt
108
Compliance is ___ dependent. When is it lower & greater?
- Volume
- lower at high volumes & higher at low volume
109
What is the normal compliance of the lung, in L/cm H2O?
0.2L/cm H2O
110
When is Elastin more compliant & important?
At low or normal lung volumes
111
What is the unit of measure for surface tension?
Dyn/cm
112
What is the formula for calculating (T)ension?
T= (P x r) / 2
113
Do smaller or larger alveoli have lower surface tension?
Smaller
114
Surfactant consists of?
- 85-90% lipids(75% phosphatidylcholine)
- 10-15% proteins
115
What is the functions of SP-A & SP-D?
Host defense
(D) for Defense
116
When does fetal surfactant production begin?
Around the fourth month of gestation.
117
What are the functions of surfactant?
- Maintain the stability of small airways
- Decrease work of inspiration by lowering surface tension --> reducing elastic recoil --> increasing compliance
118
Hypoxia or hypoxemia may lead to?
A decrease in surfactant production, inactivation or an increase in surfactant destruction
119
A lack of surfactant can temporarily be overcome by?
Ventilating someone with positive pressure (PEEP)
120
A lack of surfactant will lead to?
Increased elastic recoil of alveoli & spontaneous atelectasis.
121
What is alveolar interdependence?
Alveoli are polygons held open by the chest wall pulling on the outer surface of the lung. If an alveolus stars to collapse the surrounding alveoli will hold it open.
122
What is FRC?
- Volume of gas in the lungs at the end of eupnea.
- No muscles are actively contracting.
123
When are the elastic recoil & chest wall recoil equal?
At FRC
124
At high lung volumes the chest wall recoil pressure is positive or negative?
Positive
125
What are the FRC’s, in a healthy person, when standing & supine & at 30degrees?
- Standing= 3L
- Supine= 2L
- 30°= 2.5L
126
What kind of airflow is present in the trachea & larger airways?
Either turbulent or transitional
127
With what can alveolar pressure be measured?
With a body ple/thys/mo/graph
(4 syllable)
128
What is vital capacity?
Volume of air one is able to expire after maximal inspiration
129
Describe a FVC (Forced Vital Capacity) test & what is it used for?
- A person max inhales to TLC then gives max effort to exhale. Only the RV is left.
- It is used as a good index of expiratory airways resistance.
130
Lung volume is measured with a ___ & airflow rate is determined by using a ___?
Spirometer & (pneumo)(tacho)(graph)
131
What muscle(s) tighten the vocal folds?
- Cricothyroid muscles
- Vocalis muscle
132
What muscle(s) adduct the vocal folds?
- Thyroarytenoid muscles
- Transverse arytenoid muscle
- Lateral cricoarytenoid muscle
- (3x arytenoid, + 1x thyro + 1x crico)
133
What muscle(s) abduct the vocal folds?
Posterior cricoarytenoid muscles
134
What is the only extrinsic laryngeal muscle?
The Cricothyroid muscle
135
Which lobe is the largest & the smallest?
- Largest= Left Superior lobe
- Smallest= Left inferior lobe
136
What is in-between the thyroid cartilage & the cricoid cartilage?
The median cricothyroid ligament
137
Increased interstitial pressure leads to____ PVR due to____?
- Increased
- due to compression of vessels
138
How does positive pressure ventilation affect alveolar vessels?
They are compressed and derecruited
139
What intrapleural vessels are affected by positive pressure ventilation?
Extraalveolar & vena cava are compressed
140
What active influences can decrease PVR?
- ACh is #1
- beta-adrenergic agonists
- bradykinin
- nitric oxide
- PGE1
- prostacyclin
- PSNS stimulation
A, B2, N, P3
141
What active influences can increase PVR?
- alveolar hypoxia & hypercapnia
- angiotensin
- Alpha adrenergic agonists
- Epinephrine/Norepinephrine
- endothelin
- histamine
- PGF & PGE2
- pH (low mixed venous)
- SNS stimulation
- thromboxane
142
What is the partial pressure & percentage of atmospheric N2?
- 600.3 mmHg
- 79%
143
What is the partial pressure & percentage of atmospheric O2?
- 159.0 mmHg
- 21%
144
What is the partial pressure & percentage of atmospheric CO2?
0.3 mmHg & 0.04%
145
Describe perfusion of Zone 1?
- No perfusion during any part of the cardiac cycle.
- Higher resistance
- less recruitment
- lower intravascular pressures.
146
Describe perfusion of Zone 3?
- Perfusion is continuous due to higher pressures.
- Lower resistance
- more recruitment & distention.
147
Describe ventilation of Zone 1?
- Alveolar pressure is > arterial pressure, which is > venous pressure.
- Alveoli are larger
- less compliant
- less ventilation.
148
Describe ventilation of Zone 3?
- Arterial pressure is > venous pressure, which is > arteriolar pressure.
- Smaller transmural pressure gradient.
- More compliant & smaller alveoli.
149
Describe ventilation of Zone 4?
Zone 4 has continuous blood flow but perfusion is a bit lower than Zone 3 due to compression of the lung’s weight.
150
What is the blood flow like in Zone 2?
It is more of a pulsatile flow
151
When is PVR at the lowest point?
At FRC
152
Increasing lung volume leads to?
Decreased extra alveolar resistance & a big increase in alveolar resistance
153
How is resistance affected by decreasing lung volume?
- High increase in extraalveolar resistance
- slight decreased alveolar resistance
154
How does a cardiac index of 1.5 affect PVR?
Low blood flow results in a very high PVR
155
What is the formula for Partial pressure?
Pp= total pressure x gas concentration [Pp= 760 mmHg x 0.21 (O2)]
156
What is the humidity level at sea level?
Trick question, there is non for our purposes
157
How much O2 is absorbed each breath & per min?
1) Calculate inspiration. Use Pio2 of 149 mmHg --> O2= 149 mmHg / 760 mmHg= 19.61%.
2) 350 mL x 19.61%= 68.62 mL
3) Calculate expiration of O2: PO2 is 104 mmHg --> O2= 104 mmHg / 760 mmHg= 13.68%.
4) 350 mL x 13.68%= 47.89 mL.
5) 68.62 mL – 47.89 mL= 20.73 mL O2/breath.
6) 20.73 mL O2/breath x 12 bpm= 248.76 mL O2/min
158
What is the standard PicCO2?
0.3 mm Hg
159
What is the standard PiN2?
564.0 mm Hg
160
What is the standard Pi H2O?
47 mm Hg
161
What is the formula for inspired humidified gas?
PiO2= FiO2 (Pb – PH2O)
162
What does PB stand for?
Atmospheric pressure
163
How many mL of O2 are absorbed per 1 dL?
Around 5 - 6 mL (depending on rounding)
Calculation:
- O2 inhaled per breath= 68.6 mL
- O2 exhaled per breath= 47.6 mL
- 21 mL absorbed per breath
- 21 mL x 12= 252 mL
- Minute ventilation is 4,200 mL
- 4,200 mL dived by 100 (dL)= 42 dL
- 252 mL divided by 42 dL= 6 mL
164
How much CO2 is discarded per 1 dL?
4.5 mL
165
CO2 is very ____ but O2 is not?
Water soluble
166
What are the values for deoxygenated venous blood & venous CO2?
PvO2= 40 mm Hg PvCO2= 45 mm Hg
167
What are the PAO2, PACO2 & PAN2 after equilibration?
- PAO2= 104 mm Hg
- PACO2= 40 mm Hg
- PAN2= 569 mm Hg
168
What is the normal Interstitial capillary hydrostatic pressure?
– 4 mmHg
Lange gives a range of -5 to -7 mmHg
169
What is the normal interstitial capillary oncotic pressure?
~ 8 mm Hg
170
What happens when we have decreased colloids or diluted blood?
Extra fluid will accumulate in the lungs
171
What is the Starling Capillary Equation?
Qf= [ Kf(Pc – Pis) – 𝞂(πpl – πis) ]
172
What does 𝞂 stand for?
Reflection coefficient (ability of membrane to prevent leakage.
173
What does Kf stand for?
Capillary filtration coefficient (permeability characteristics of the membrane to fluids)
174
What happens to small blood vessels during inspiration?
Their diameter is reduced & increased in length --> increased resistance
175
What happens to extra-alveolar vessels during inspiration?
The negative pressure pulls on them --> increased diameter --> decreased resistance.
176
At low lung volumes, alveolar vessel resistance ___?
Decreases
177
What is the minimum PAO2 someone can still be healthy at?
40 mm Hg
178
What is the formula for Alveolar ventilation?
VA= RR x VA (VA per min= 12 x 350 mL)
179
How does increased metabolism affect PAO2 & PCO2?
- PAO2 is reduced
- PCO2 is increased
180
What happens to alveolar capillaries in responds to elevated CO2?
They constrict --> O2 being absorbed but no new air coming in & CO2 will build up.
181
What is HPV?
- Hypoxic pulmonary vasoconstriction.
- Areas with low perfusion get “constricted” to move fresh air to well perfused areas
182
What & why should someone with HPV not receive?
- Increased inspired O2.
- This will lead to O2 entering low or none perfused alveoli, which were previously constricted & take air away from functional areas
183
What happens if someone receives 100% FiO2 over several days?
Inflammation throughout the lung
184
How do anesthetics affect HPV?
All anesthetics knock out the HPV function
185
Squeezing ones' abdomen results in ____ thoracic pressure?
Increased
186
At RV the apex is more/less compliant than the base?
- More.
- Base is most likely collapsed and increased pressure is needed to recruit them first.
187
Calculate FRC with the following values: Spirometer= 20L + 15% of that is Helium, final He concentration is 14%?
1) 20 L x 0.15%= 3L
2) X= 3 L / 0.14% = 21.43 L --> FRC= 1.43 L
188
What should one living in a basement in Michigan test for?
Radon (Rn), which is the 2nd leading cause of lung cancer
189
-Emphysema is a/n ___disease due to the ___ of ___.
- Obstructive,
- Loss & recoil
190
What ventilator mode should not be used in emphysema Pt’s?
Positive pressure ventilation --> small airways collapse
191
Fibrosis is a/n ___ disease leading to ___ compliance?
- Restrictive
- Decreased
192
What is Radon’s atomic number & weight?
86 & 222
193
Filling lungs strictly with water results in?
- No surface tension
- increased compliance
194
Surface tension makes up how much of the recoil tension?
2/3
195
Increased surface tension leads to?
Increased work to inhale
196
What slows down intrinsic digestion of the lungs?
Alpha1 Antitrypsin
197
What is ⍺1 A/T & where is it produced & with what disease is it inhibited?
- It is a antiprotease & is produced in the liver.
- Inhibited in emphysema
198
What happens to TLC, IC, FRC, VC, IRV, VT, ERV & RV in restrictive diseases?
They all are reduced.
199
SP-D & SP-A are ___ & SP-C & SP-B are ____?
Hydrophilic & Hydrophobic
200
What are the functions of surfactant’s lipids?
- Lower surface tension
- change proliferation & cytotoxicity of lymphocytes.
201
What are the functions of surfactant’s proteins?
- Enhance chemotaxis & phagocytosis
- Aggregation & opsonization of micro-organisms
- Inhibit the growth of pathogens
202
What is a normal V/Q ratio & how is it calculated?
- 0.8 L/min
- Calculated by V= 4.2 L/min / Q= 5 L/min
203
Zone 3 has a higher V/Q ration than Zone 1?
False, the lower lung has a lower V/Q despite increased perfusion
204
Compare expired PO2 & CO2 of the upper & lower lung?
- Upper lung will have higher PO2 & lower CO2.
- Lower lung will have lower PO2 & higher CO2
205
An airway obstruction will cause a ___ V/Q ratio?
Low (Low ventilation= usually low V/Q ratio)
206
How much lung volume is lost in the supine position?
About 1L
207
What happens to TLC, FRC, VC, VT, ERV & RV in obstructive diseases?
TLC, FRC, VT & RV are increased. VC & ERV are reduced.
208
Why is the RV important in healthy people?
It prevents the lungs from collapsing
209
Explain ERV?
Volume of gas expelled during max force. It starts after normal Vt expiration
210
IRV is determined by?
Strength of inspiratory muscles, inward elastic recoil of the lung & chest wall
211
What would be a normal reason for FRC to be lower than usual?
Exercise
212
When does IC begin?
At the end of normal expiration
213
Explain VC?
- Volume of air expelled during max forced expiration.
- Starts after maximal forced inspiration
214
What happens to the FRC, ERV, IRV, VC, RV & TLC when going from standing to supine?
- FRC decreases due to gravity no longer pulling on diaphragm.
- VC, RV & TLC do not change significantly but may slightly decrease d/t venous blood collecting in the lower extremities.
- ERV decreases.
- IRV increases
215
What lung volumes can be measured with a spirometer?
VT
IRV
ERV
IC
VC
FEV1
FVC
216
What lung volumes cannot be determined with a spirometer?
RV
FRC
TLC
217
Why is Helium used in PFT?
It is not taken up by pulmonary capillary blood & it does not diffuse out of the blood.
218
At what exact moment is the Helium-dilution technique stopped?
At the end of normal tidal volume
219
What is a reasonable estimate for anatomic dead space?
1 mL of dead space per pound of ideal body weight
220
How much CO2 comes from dead space?
Trick question, none
221
When seated which alveolar regions receive more ventilation per unit volume?
The lower regions.
222
Where in the lung is most ERV, IRV & IC located?
- ERV= In the upper portions
- IRV & IC= in the lower regions
223
Explain the air path when starting to inhale from RV?
The initial air enters the nondependent upper alveoli then the lower alveoli fill.
224
Where would airway closure most likely happen & why?
- In the lower parts of the lungs.
- The alveoli are smaller & have less recoil pressure.
225
Kyphoscoliosis is what kind of disease in relation to airway?
- A restrictive disease.
- It results in decreased compliance of the rib cage with much less outward recoil at low thoracic volumes & much greater inward recoil at higher volumes.
226
Why is the RV important in healthy people?
It prevents the lungs from collapsing
227
Explain ERV?
Volume of gas expelled during max force. It starts after normal Vt expiration
228
IRV is determined by?
Strength of inspiratory muscles, inward elastic recoil of the lung & chest wall
229
What would be a normal reason for FRC to be lower than usual?
During exercise
230
When does IC begin?
At the end of normal expiration
231
Explain VC?
Volume of air expelled during max forced expiration. Starts after maximal forced inspiration
232
What happens to the FRC, ERV, IRV, VC, RV & TLC when going from standing to supine?
- FRC decreases due to gravity no longer pulling on diaphragm.
- VC, RV & TLC do not change significantly but may slightly decrease d/t venous blood collecting in the lower extremities.
- ERV decreases
- IRV increases
233
What lung volumes can be measured with a spirometer?
VT, IRV, ERV, IC, VC & FEV1, FVC
234
What lung volumes cannot be determined with a spirometer?
RV, FRC & TLC
235
Why is Helium used in PFT?
- It is not taken up by pulmonary capillary blood &
- it does not diffuse out of the blood.
236
At what exact moment is the Helium-dilution technique stopped?
At the end of normal tidal volume
237
What is a reasonable estimate for anatomic dead space?
1 mL of dead space per pound of ideal body weight
238
How much CO2 comes from dead space?
Trick question, none
239
When seated which alveolar regions receive more ventilation per unit volume?
The lower regions.
240
Where in the lung is most ERV, IRV & IC located?
- ERV= In the upper portions IRV &
- IC= in the lower regions
241
Explain the air path when starting at RV?
The initial air enters the nondependent upper alveoli then the lower alveoli fill.
242
Where would airway closure most likely happen & why?
- In the lower parts of the lungs.
- The alveoli are smaller & have less recoil pressure.
243
Kyphoscoliosis is what kind of disease in relation to airway?
- A restrictive disease.
- It results in decreased compliance of the rib cage with much less outward recoil at low thoracic volumes & much greater inward recoil at higher volumes.
244
Increasing transmural pressure difference leads to___ vessel diameter & ___ resistance?
Increased & Decreased
245
With high lung volumes, resistance to blood flow offered by the alveolar vessels ___?
Increases greatly
246
How does positive-pressure ventilation affect alveolar & intrapleural pressures?
- Both pressure will be positive during inspiration.
- Alveolar & extraalveolar vessels are compressed & resistance to blood flow increases.
247
When would alveolar & intrapleural pressures be positive during inspiration & expiration?
- During positive-pressure ventilation w/ PEEP --> increased PVR & decreased transmural pressure differences.
- CV reflexes should adjust. If not CO will fall dramatically.
248
How does tripled CO affect PVR?
PVR is decreases passively due to recruitment, distention or both
249
Neural effects innervate which pulmonary vessels?
- Larger vessels are innervated more than smaller vessels.
- No innervation of vessels smaller than 30µm
250
When does perfusion cease?
When alveolar pressure is equal to pulmonary artery pressure
251
How does exercise affect Zones 1-3?
Zone 1 will turn into Zone 2 & the zone boundaries will move upward
252
How does the CNS control HPV?
Trick question, it does not. (Pg 111 in Lange)
253
How is HPV regulated on a cellular level?
Hypoxia inhibits an outward K+ current, which causes pulmonary vascular smooth muscle to depolarization, allowing calcium to enter the cells leading to contraction.
The K+ channel is open when oxidized & closed when reduced.
Lange page 111 (Hypoxic HPV)
254
How does alkalosis affect HPV?
It can interfere with HPV & open up previously closed areas.
255
How do ARDS, O2 toxicity & inhaled toxins lead to pulmonary edema?
Increase capillary permeability (Kf, 𝞂)
256
How do increased LA pressure, MS & too much IVF lead to pulmonary edema?
Increase capillary hydrostatic pressure (Pc)
257
How do rapid hemo/pneumothorax evacuation or upper airway obstruction lead to pulmonary edema?
Decreasing interstitial hydrostatic pressure (Pis)
258
How do protein starvation, diluted blood proteins & proteinuria lead to pulmonary edema?
Decrease the colloid osmotic pressure (πpl)
259
Label # 1 thru 6
1) Tubular myelin
2) Type 1 cell
3) Type 2 cell
4) Macrophage
5) Multivesicular bodies
6) Lamellar bodies
260
What is the Bohr's equation to calculate physiologic dead space?
Vd / Vt = (Paco2 - Peco2) / Paco2
Example: Vd / 500 mL = (44 mmHg - 30 mHg) / 44 mmHg
--> Vd = (14 mmHg / 44 mmHg) x 500 mL
--> Vd = 0.318 mmHg x 500 mL
--> Vd = 159.01 mL
261
What is the formula to calculate alveolar oxygen tension?
PAO2 = FiO2 (PB - PH2O) - (PaCO2 / R)
Example:
--> PAO2 = 0.70% (760 mmHg - 47 mmHg) - (40 mmHg / 0.8)
--> PAO2 = (0.70% x 711 mmHg) - 50 mmHg
--> PAO2 = 499.1 mmHg - 50 mmHg
--> PAO2 = 449.1 mmHg
262
PiO2 can be substituted with what?
PiO2 = FiO2 (PB - PH2O)
263
What is the formula to calculate A-a gradient?
PAO2 = PiO2 - ( PaCO2 / R )
PiO2 can be substituted with [ FiO2 x (PB - PH2O) ]
