Respiratory Pathophysiology Flashcards
(130 cards)
1
Q
Purpose of the pulmonary system
A
supply oxygen from the atmosphere to the blood and remove CO2, maintain acid base balance, phonation, pulmonary defense, oxygen for metabolism
2
Q
Partial pressure of gases in air
A
79% Nitrogen, 600 mmHg
21% Oxygen 159.6 mmHg
1% Carbon Dioxide and other gases
3
Q
Glycolysis in anaerobic metabolism
A
not sustainable for life
inefficient because it only yields 2 ATP
happens in the cytoplasm
4
Q
Byproducts of the Aerobic metabolism
A
CO2, H2O, heat
5
Q
Anaerobic metabolism
A
glycolysis –> 2 ATP and goes thru fermentation turning pyruvate into lactate
6
Q
Purpose of the nose
A
used for filtration, smell, and humidification of incoming air
7
Q
3 paired cartilages of the larynx
A
corniculate, arytenoid, and cuneiform
8
Q
3 unpaired cartilages of the larynx
A
epiglottis, thyroid, cricoid
9
Q
Why is the right mainstem bronchus more likely to be intubated over the left?
A
shorter, wider, and more vertical (25 degree angle)
10
Q
the right lung makes up ____ TLC and is divided into ___ lobes
A
55%; 3
11
Q
the left lung makes up ___ TLC and is divided into ___ lobes
A
45%; 2
12
Q
Conducting zones of the airway
A
trachea –> bronchi –> bronchioles
No gas exchange occurs - anatomic dead space
has goblet cells- secrete mucus
the terminal bronchioles measure 1mm in diameter and lose cartilaginous plates
13
Q
Resiratory/Transitional zones of the airway
A
terminal bronchioles –> alveolar ducts –> alveolar sacs
where gas exchange occurs - gas moves by diffusion
no goblet cells
respiratory bronchioles have diameter of 0.5 mm
14
Q
What is the primary muscle of ventilation?
A
the diaphragm
15
Q
What innervates the diaphragm?
A
C-3-4-5 roots to the phrenic nerve
16
Q
When are intercostal muscles primarily used?
A
exertion
external - forced inhalation
internal - forced expiration
17
Q
What the 3 types of pneumocytes in the lungs?
A
type 1 - structural
type 2 - surfactant producing
type 3 - macrophages
18
Q
The distance from front incisors to carina is
A
26 cm
front incisors to larynx - 13 cm
larynx to carina - 13 cm
19
Q
Blood supply to the conducting zone
A
from systemic circulation
from thyroid, bronchial, and internal arteries
20
Q
Blood supply to the respiratory/transitional zone
A
from the pulmonary circulation
21
Q
Anatomic dead space can be estimated by:
A
150 mLs (for a 70kg 6’0” man)
1/3 of tidal volume
1 mL/lb. or 2 mLs/kg of body weight (IBW)
22
Q
Mechanics of inspiration
A
phrenic nerve innervates diaphragm to contract
drop in intrathoracic pressure - air pulls in
external intercostal help lift sternum and elevate ribs (increases AP diameter)
23
Q
Does loss of intercostal function have an effect on ventilation?
A
not really
24
Q
Mechanics of expiration
A
passive
increase in intrathoracic pressure - push air out
the elastic forces of the lung, chest wall, and abdomen compress the lungs
internal intercostals help with forceful expiration
25
What are the inspiratory accessory muscles?
sternocleidomastoid
| scalene
26
What are the expiratory accessory muscles?
rectus, internal/external obliques, transversus abdominus
27
Transpulmonary pressure is the difference
between intrapleural and intra-alveolar pressures
28
What does the transpulmonary pressure determine?
the size of the lungs
| a higher pressure = larger lung
29
Components of WOB
elastic and resistance forces of the lung and chest wall
30
Dorsal respiratory group stimulates
inspiration
31
Ventral respiratory group stimulates
inspiration/expiration (helps with forced inspiration/expiration)
32
the pneumotaxic center control of the lungs
decreases tidal volume
33
where is the pneumotaxic center located?
higher region of the pons
34
the apneustic center controls
increases in tidal volume for long and deep breathing
| output is limited by baroreflex input from the lung and pneumotaxic center
35
where is the apneustic center located?
lower region of the pons
36
what do central chemoreceptors respond to?
hydrogen ion levels
37
what do peripheral chemoreceptors respond to?
CO2, pH, hypoxemia
38
What is the normal stimulus to breathe?
Hypercapnia
39
Which cranial nerve carries the aortic arch and lung stretch signals to the DRG?
CN X (vagus)
40
Which cranial nerve carries the carotid body signals to the DRG?
CN IX (glossopharyngeal)
41
Parasympathetic influence on the airway
causes mucus secretion, increased vascular permeability, vasodilation, bronchospasm
42
Activation of which receptors causes bronchoconstriction?
M3
43
Sympathetic influence on airway
inhibit mediator release from mast cells, increase mucociliary clearance
44
Activation of which receptors causes bronchodilation?
Beta 2
45
Which weight should we use for setting a Vt?
always IBW!
46
What are the 4 lung volumes?
residual
expiratory reserve
tidal
inspiratory reserve
47
Which volume cannot be measured by spirometry?
residual volume
48
What are the 4 lung capacities?
inspiratory = IRV + Vt
vital = IRV + Vt + ERV
functional residual = RV + ERV
total lung = IRV + Vt + ERV + RV
49
FRC definition
represents the point where elastic recoil of the lung is in equilibrium with the elastic recoil of the chest wall
"oxygen reserve"
50
Factors that affect FRC
upright and prone position = increases FRC
supine position = decreases FRC
muscle relaxation = decreases FRC
insufflation = decreases FRC
51
What is the respiratory quotient?
0.8
52
Which pleura covers the lung and which pleura covers the chest wall?
lung: visceral pleura
| chest wall: parietal pleura
53
What is the space between the visceral and the parietal pleura called?
pleural cavity
54
Compliance =
change in volume / change in pressure
55
static compliance definition
compliance of the lung and chest wall WITH NO AIR MOVEMENT
| don't consider airway resistance*
56
What causes decreased static compliance?
fibrosis, obesity, edema, vascular engorgement, ARDS, external compression, atelectasis
57
What is the equation to calculate static compliance?
Tidal volume / (plateau pressure - PEEP)
ex. 500 / (12-5) = 71
normal value 60-100 mL/cmH2O
58
How do we measure plateau pressure?
have to set an inspiratory pause on the vent
| usually can only do in volume control mode
59
dynamic compliance definition
compliance of the lung and chest wall during a breath
| airway resistance plays a large role!
60
What causes decreased dynamic compliance?
bronchospasm, tube kinking, mucous plugs, increased RR
really anything that increases airway resistance...
61
How to calculate dynamic compliance
tidal volume / (peak pressure - PEEP)
ex. 500 / (20-5) = 33
normal 50-100mL/cmH2O
62
Where are elastic forces greatest?
in collapsed and hyperinflated alveoli
| require a greater change in pressure to achieve a set increase in volume
63
What plays the largest role in reducing surface tension
| ?
surfactant
64
Laminar flow is mostly
in small airways
65
Turbulent flow is mostly
in large airways
66
Where is the greatest airway resistance?
in the medium sized bronchi
67
What does the Reynolds number predict?
when flow will be laminar or turbulent
68
What has the biggest impact on the Reynolds number?
diameter of the vessel
69
Which west zone should a PA catheter tip be placed in?
zone 3
70
Zone 1 pressure in order of greatest to least
alveolar > arterial > venous
| V/Q >1
71
Zone 2 pressure in order of greatest to least
arterial > alveolar > venous
| V/Q = 1
72
Zone 3 pressure in order of greatest to least
arterial > venous > alveolar
| V/Q = 0.8
73
Zone 4 pressure in order of greatest to least
arterial > interstitial > venous > alveolar
| V/Q < 1
74
Denitrogenation always causes some degree of ___
atelectasis
75
Closing volume definition
is the volume above residual volume where small airways close
76
closing capacity definition
absolute volume of gas in the lung when small airways close (CV + RV)
increases from 30% of TLC at age 20 to 55% by age 70
increased by supine position, pregnancy, obesity, COPd, CHF, aging
77
If closing volume is greater than FRC
airway closure occurs during tidal breathing leading to poorly ventilated alveoli and shunting
78
oxygen in the blood is carried in two ways
1. physical - dissolved in blood
2. chemical - bound to Hgb
Hgb rapidly and reversibly binds oxygen, allowing oxygen to be released into the tissues
79
Each Hgb molecule binds up to ___ oxygen molecules
4
80
Each gram of Hgb binds ____ mL of oxygen
1.34
81
Right shift on oxy/hgb dissociation curve
lower affinity at tissue level (increase CO2, increase temp, decreased pH, decreased O2, increased 2,3 DPG)
82
Left shift on oxy/hgb dissociation curve
higher affinity at lungs (decrease CO2, decreased temp, decrease 2,3 DPG, increase pH)
83
Haldane effect
in the lung
oxygenation of blood displaces carbon dioxide from hemoglobin
shows relationship for blood's ability to carry CO2 in different oxygen environments
curve shifts up and left when PO2 decreases
84
Bohr effect
in the tissue
| hemoglobin's affinity for o2 is inversely related to CO2 levels
85
SaO2 50% ... PaO2 =
27
86
SaO2 70% ... PaO2 =
40
87
SaO2 90% ... PaO2 =
60
88
CO2 is transported in the blood by
1. physical solution 5-10% (dissolved in blood)
2. chemically combined with amino acids of blood proteins 5-10% (bound to Hgb)
3. bicarbonate ions 80-90%***
89
What is the equation for rapid conversion of CO2 into bicarb?
CO2 + H2O --> carbonic anhydrase --> HCO3- + H+
90
What is the chloride shift?
HCO2 leaves the RBCs, chloride enters to maintain electrical neutrality in the tissue capillaries
91
What is the quickest compensation for acid base imbalances?
serum buffers
92
Hypoxic hypoxia caused
```
from:
decrease FiO2 <0.21
alveolar hypoventilation
V/Q mismatch
R --> L shunt
```
93
Clinical examples of hypoxic hypoxia
high altitude, O2 equipment error, drug overdose, COPD, pulmonary fibrosis, PE, atelectasis, congenital heart disease
94
Examples of circulatory hypoxia
reduced cardiac output
| severe HF, dehydration, sepsis, SIRS
95
Clinical examples of hemic hypoxia
reduced Hgb content/function
| anemias, carboxyhemoglobinemia, methemoglobinemia
96
Which hypoxia would supplemental oxygen be helpful?
hypoxic hypoxia* and demand/histotoxic hypoxia
97
Clinical examples of demand/histotoxic hypoxia
increased O2 consumption or inability to utilize O2
| fever, seizures, cyanide toxicity
98
Hypoxic pulmonary vasoconstriction definition
reflex contraction of pulmonary vasculature in response to a low regional partial pressure of oxygen
intended to match regional perfusion to ventilation in the lungs
99
how does the HPV response work
diverts blood away from hypoxic areas of the lungs to areas with better ventilation and oxygenation
100
What does pulmonary circulation do in a hypoxic environment (acidic) ?
vasoconstrict
101
How is HPV reduced/eliminated?
elevated FiO2, volatile anesthetics above 1 MAC
102
Which disease has constant HPV if not treated and what can it lead to?
OSA, can lead to pulmonary HTN
103
causes of deadspace
PE, hypovolemia, cardiac arrest, shock
anything that decreases pulmonary blood flow
104
causes of shunts
mucus plugging, right mainstem intubation, atelectasis, pneumonia, pulmonary edema
anything that causes alveoli to collapse or fill
105
difference between anatomic and alveolar dead space
anatomical - air in the airway that never reaches the alveoli and does not participate in gas exchange
alveolar - air in nonfunctioning alveoli (disease or abnormal blood flow)
106
physiologic dead space =
alveolar + anatomic dead space
| represents all of the air that is not being used for gas exchange
107
Bohr's Equation in terms of dead space
deadspace = Vt [(PaCO2 - PeCO2) / PaCO2]
| ex. 55 x [(45 - 32) / 45] = 144 mL
108
PeCO2 is normally ____ less than PaCO2
2-5 mmHg
| due to mixing with anatomic deadspace during exhalation
109
venous admixture is the result of
mixing of non-oxygenated blood with oxygenated blood distal to the alveoli
110
mixed venous oxygen tension (PVO2) represents
overall balance between O2 consumption and o2 delivery
111
factors that lower PVO2
decreased CO, increase O2 consumption, decreased Hgb concentration
112
absolute shunt
V/Q = 0
| hypoxia unresponsive to supplemental oxygen
113
Shunt
wasted perfusion - airway obstruction, pneumonia
| low V/Q
114
Dead space
wasted ventilation - pulmonary embolism, cardiogenic shock
| high V/Q
115
Shunt like alveoli have ___ PO2 and ___ PCO2
low PO2 and high PCO2
116
deadspace like alveoli have ___ PO2 and ___ PCO2
high PO2 and low PCO2
117
Symptoms of URI
elevated WBC, mucopurulent nasal secretions, inflamed and reddened mucosa, congestion/rales, temp >37, tonsillitis, viral ulcer, fatigue, laryngitis, sore throat
118
Histamine related allergy symptoms
sneezing, ash or boggy mucosa, itchy/runny nose, conjunctivitis, wheezing, hives, facial swelling, dry,red and cracked skin
119
Fick's Law of Diffusion
Rate of gas diffusion = D x A x deltaP / T
D = diffusion coefficient of gas
A = surface Area
deltaP = difference in partial pressure of gas across membrane
T = thicc ness ;-)
120
Alveolar gas equation
PAO2 = (PB - PH2O) x FiO2 - (PACO2 / 0.8)
ex. (760 - 47) x .21 - (40 /0.8) = 100
PB = barometric pressure
121
A-a Gradient
PAO2 - PaO2
ex. 100-92 = 8
normal 5-15
increases with age, obesity, supine position, heavy exercise
122
What equation is a good indicator of overall gas exchange?
A/a ratio
PAO2 / PaO2
normal >75%
123
Oxygen content equation
CaO2 = (HB x 1.34 x SaO2) + (PaO2 x 0.003)
CaO2 = 20.4
CvO2 = 15 mL o2/100mL blood
CaO2 - CvO2 = 5 mL O2/100 mL blood (consumption)
124
Oxygen delivery
= CO x CaO2
| ex. 5 x 200 = 1000mL/min
125
Fick Equation/Oxygen consumption
VO2 = CO x (CaO2 - CvO2)
| ex.. 5 x (200-150) = 250mL/min
126
CO2/Alveolar ventilation equation
PaCO2 = VCO2 / VA
| shows that PACO2 levels are inversely proportional to alveolar ventilation
127
PaO2/FiO2 ratio (P/F ratio)
= PaO2 / FiO2
ex. 100 / .21 = 476
normal 400-500
128
P/F ratio <300 indicates
mild ARDS
129
P/F ratio <200 indicates
moderate ARDS
130
P/F ratio < 100 indicates
severe ARDS
