Respiratory Flashcards
(86 cards)
1
Q
What does a right shift of the Hb-oxygen dissociation curve mean?
What causes it?
A
Shifting to the right means increased unloading of oxygen to the tissues
Seen with acidosis, increased PCO2 (hypercarbia), increased temp (heat) and increased 2,3 DPG in RBC
2
Q
What does a left shift of the Hb-oxygen dissociation curve mean?
What causes it?
A
Shifting to the left means decreased unloading of oxygen to the tissues
Alkalosis, hypothermia
3
Q
How does the O2-hemoglobin curve shift in acidemia
A
Right
4
Q
How does the O2-hemoglobin curve shift with increased CO2 concentrations?
A
Right
5
Q
How does the O2-hemoglobin curve shift in decreased temperatures?
A
Left
6
Q
How does the O2-hemoglobin curve shift in increased 2,3-DPG?
A
Right
7
Q
What is the Bohr effect?
A
Increased CO2 and H+ → decreases affinity of Hb for O2 and promotes offloading
8
Q
What forms does CO2 exist in the blood?
A
- HCO3 - most
- Carbamino compounds
- Dissolved in plasma
9
Q
What is the Haldane effect?
A
Dexoygenated haemoglobin is better at carrying CO2
10
Q
What is the difference between the Bohr and Haldane effects?
A
- Bohr → increase in CO2 (or H+) in blood causes O2 to be displaced from haemoglobin (tissues)
- Haldane → binding of O2 with hemoglobin causes CO2 to be displaced from the hemoglobin (lungs)
11
Q
Where are the peripheral chemoreceptors?
A
Aortic and carotid bodies
12
Q
Where are the central chemoreceptors located?
A
The respiratory centre in the medulla and the pons
13
Q
How do the central chemoreceptors work?
A
Respond to increasing H+ by increasing ventilation
H+ cannot cross BBB
CO2 in the blood rises, diffuses in to CSF, and Hydrogen ions dissociate
Not influenced by PO2
14
Q
Parasympathetic stimuation (ACh) causes what effect in the lung?
A
BronchoCONSTRICTION
15
Q
Sympathetic stimualtion (Epi/Norepi) causes what effect in the lung?
Via which receptor?
A
BronchoDILATION
B2 adrenergic receptors
16
Q
What compose the conducting airways?
A
Trachea and bronchi
*Anatomic dead space
17
Q
What cells secrete secrete surfactant?
A
Type II alveolar epithelial cell
18
Q
Which alveolar epithelial cells are most abundant?
A
Type 1 - 95%
19
Q
What are the roles of type 2 alveolar epithelial cells
A
- Stem cells from which type 1 cells arise
- Produce/Store surfactant
20
Q
What is surfactant composed of?
A
80% phospholipids (contains DPPC)
20% neutral lipids and proteins
21
Q
What muscle(s) plays a role in the process of inspiration?
A
- Diaphragm → contracts and flattens, causes intrapleural space to become more negative
- External intercostals → make diaphragm contraction more efficient, greater role during exercise
22
Q
What nerve innervates the diaphraghm?
A
Phrenic nerve originating from cervical segments 3-5
23
Q
What muscle(s) plays a role in the process of expiration?
A
- Typically a passive process
- Abdominal muscles push diaphragm up → increase the intrapleural pressure
- Internal intercostals → oppose action of external intercostals, pull ribcage down and in
- Accessory muscles → laryngeal muscles, act as “breaks”
24
Q
What components determine lung compliance?
A
- Elastic forces of the lung → elastin and collagen fibers
- Surface tension of the alveoli mediated by surfactant
25
What is tidal volume?
Volume of air inspired or expired with each normal breath
10-15 ml/kg
26
What is the inspiratory reserve volume?
The extra volume of air that can be inspired OVER the normal tidal volume
27
What is the inspiratory capacity?
Tidal volume + inspiratory reserve volume
The total amount of air that an individual can breathe in
28
What is the expiratory reserve volume?
The extra volume of air that can be expelled by an active expiratory effort AFTER passive expiration
29
What is the the residual volume?
The volume of air remaining in the lungs after the most forceful expiration
30
What is the functional residual capacity?
The amount of air that remains in the lungs at the end of normal expiration
31
What is the vital capacity?
Tidal volume + inspiratory reserve volume + expiratory reserve volume
The maximum amount of air an individual can expel from the lungs after filling the lungs to the maximum extent and then expiring to a maximum extent
32
What is the total lung capacity?
Vital capacity + residual volume
The maximum amount of air the lungs can be expanded with the greatest amount of effort
33
What factors affect diffusion in the lung?
1. Thickness of membranes
2. Surface area
3. Diffusion coefficient of gas
4. Partial pressure difference
34
What is Fick's law
Ficks law states that the rate of diffusion of a gas through a tissue sheet is proportional to the area and pressure difference across it, and inversely proportional to the thickness
35
What happens to the blood vessel if the concentration of O2 in an alveoli decreases?
Blood vessels constrict → increase vascular resistance
Distributes blood flow to where the lungs are better aerated
36
What occurs to V/Q in the following scenarios?
1. Without ventilation
2. Without perfusion
1. V/Q = 0
2. V/Q = infinity
37
What diseases can lead to a low V/Q (poor ventilation, decreased PaO2)
1. Chronic bronchitis
2. Asthma
3. Pulmonary edema
Ventral lungs have slightly lower V/Q
38
What diseases can lead to a high V/Q (poor perfusion, increased PaCO2)
1. Pulmonary thromboembolism
* Dorsal lungs have a slightly higher V/Q
39
What can cause pulmonary edema (general mechanisms)?
1. Increased hydrostatic pressure
2. Decreased oncotic pressure
3. Failure of lymphatic drainage
4. Increased vascular permeability
40
What is perfusion limited gas exchange?
Illustrated by O2 and NO
- The gas equilibrates early along the length of the pulmonary capillary
- The partial pressure of the gas in arterial blood becomes equal to the partial pressure in the alveolar air
- Diffusion of the gas can only be increased with increased blood flow
41
What is diffusion limited gas exchange?
Illustrated by CO
- The gas does not equilibrate by the time the blood reaches the end of the pulmonary capillary
- The partial pressure of the gas between alveolar air and pulmonary capillary blood is maintained
- Diffusion continues as long as the partial pressure gradient is maintained
42
What are the 5 causes of hypoxemia?
Which will not respond to oxygen therapy?
1. Hypoventilation (Decreased PAO2)
2. Diffusion impairment
3. V/Q Mismatch
4. Shunts
5. Low FiO2
*Shunt will not respond to 100% O2
43
What are the causes for tissue hypoxia?
* Hypoxic hypoxia (low blood oxygen overall)
* Anemia hypoxia (recall the oxygen content equation)
* Circulatory hypoxia (decreased tissue perfusion)
* Histotoxic hypoxia (Cyanide)
44
In what zone of the lung is blood flow the lowest?
1. Zone 1
45
Where is the V/Q ratio the highest?
The apex
46
How are PO2 and PCO2 affected in airway obstruction?
V/Q = 0
Will approach their values in mixed venous blood
47
How are PO2 and PCO2 affected in pulmonary embolism?
V/Q = infinity
Will approach their values in inspired air
48
What is normal tidal volume?
10-15 ml/kg
49
The A-a gradient should always be (number)
<10-15
50
What does an increased A-a gradient indicate?
1. Shunt
2. V/Q Mismatch
3. Diffusion impairment
51
A low PaO2, high PCO2, and normal A-a gradient would indicate what?
Hypoventilation with normal lungs
52
The (PO2/PCO2) is the most important regulator of ventilation and most of the control is via the (peripheral/central) chemoreceptors
1. PCO2
2. Central
53
Peripheral chemoreceptors respond to changes in which gases
* Respond non-linearly to changes in PaO2, with maximum response when PaO2 < 50 mmHg
* Also respond to increased PCO2 and H+, more rapidly than central
54
Which chemoreceptors can respond to hypoxia?
Peripheral
55
Which conditions will not respond to 100% oxygen supplementation?
1. Cyanide toxicity
2. Shunt
3. V/Q to infinity (ventilation but no perfusion)
56
How does the lung adapt to accommodate more blood during exercise?
Increases pulmonary blood flow (blood vessel dissension)
Decreases physiologic dead space (blood vessel recruitment)
57
What does a right shift of the oxygen dissociation curve mean?
Right shift = decreased oxygen affinity of haemoglobin allowing more O2 release to tissues
58
What are the 4 types of lung receptors
* Pulmonary stretch receptors (slow acting)
* Irritant receptors (fast acting stretch receptor - bronchoconstriction and hyperpnea)
* J receptors
* Bronchial C Fiber
| REATHING)
59
What is the A-a gradient and how do you calculate it
The A-a gradient is the difference between the theoretical value of oxygen partial pressure in the alveolus (PAO2) and the actual partial pressure of oxygen in the blood (PaO2).
PAO2 = FiO2 x (Atmospheric Pressure (760mmHg) – Saturated Water Vapour Pressure (47mmHg)) – 1.2(PCaO2).
So - PAO2 = 150 – 1.2(PaCO2)
A-a gradient = PAO2-PaO2 or
A-s = 150 – 1.2(PaCO2) - PaO2
60
What is the P/F ratio and how do you calculate it?
PaO2/FiO2
Normal PaO2/FiO2 on room air should be approx. 470
Mild ARDS < 300
Moderate ARDS <200
Severe ARDS <100
61
How is total ventilation or minute ventilation calculated?
minute ventilation = tidal volume x respiration frequency
Tidal volume in a normal dog = 10-20ml/kg
62
How is alveolar ventilation calculated?
Alveolar ventilation is the volume of fresh gas (non-dead space) entering the respiratory zone per minute
(Vtidal - Vdead space) x no of breaths per minute
63
What is the difference between anatomic and physiological dead space?
* Anatomic dead space is the volume of the conducting airways - approx. 150ml in the adult
* Physiologic dead space is the volume of gas that does not eliminate CO2
* Physiologic dead space is affected by lung disease
64
What are the other function of the lung apart from gas exchange?
* removal of vasoactive substanceds (Serotonin, bradykinin, Norepinephrine, AT1)
* Biological activation (ACE)
* Coagulation
* Synthesis (surfactant, mucous IgA)
65
What are the main differences of pulmonary circulation compared to systemic?
* Low pressure - Mean PA pressure is 15mmHg
* Thin vessel walls - arteries lack smooth muscle in walls
* Pressure from alveoli can collapse surrounding capillaries
66
How do you calculate vascular resistance
What is the calculation for pulmonary vascular resistance
(input pressure - output pressure) / blood flow
mean PA pressure - LA pressure/cardiac output
67
An initial increase in mean PA pressure or venous pressure will cause what to happen to PVR?
Decrease in PVR due to recruitment and distension of capillaries
68
Which local vasoactive substances can cause vasodilation
Nitric oxide, Sildenafil, Endothelin 1
69
Inspiratory dyspnoea indicates what
Upper airway obstruction
70
Expiratory dyspnoea indicates what
lower airway disease
71
A restrictive breathing pattern indicated what type of disease
Pleural space disease
72
Eosinophilic bronchopneumopathy typically affects what breed
Siberian Huskies and Malamutes
73
Laryngeal paralysis typically affects which dog breeds
Labrador Retrievers, Golden Retrievers, Saint Bernards, Newfoundland's, Irish Setters, and Brittany Spaniels
74
laryngeal paralysis is suspected to be part of which degenerative condition
geriatric-onset laryngeal paralysis polyneuropathy (GOLPP)
75
Tracheal collapse is msot common in which dog breeds
Yorkshire Terriers, Pomeranians, Pugs, Poodles, Maltese, and Chihuahuas
76
Which cat breed appears pre-disposed to feline lower airway disease
Siamese
77
Paragonimus kelicottis
- distribution
- transmission
- pathology
- Great lakes region
- crayfish ingestion
- Forms bullae and cysts in lung tissue
78
Filaroides species
- location in respiratory system
Alveolar spaces and termial bronchioles in dogs
79
Oslerus osleri
- location in respiratory system
Adult worms occur in nodules clustered at the bifurcation of the trachea
80
Which breed is predisposed to idiopathic pulmonary fibrosis (IPF)
Westies
81
Pulmonary hypertension is determined by an
abnormal elevation in pulmonary systolic
or diastolic pressure greater than approximately
30/19mmHg or a mean of 20-25mmHg
82
What are the mechanisms that pulmonary hypertension can develop by
* Increased pulmonary blood flow/cardiac output
* Increased pulmonary vascular resistance (PVR)
* Increased pulmonary venous pressure
83
What is precapillary pulmonary hypertension
Due to increased PVR without increased pulmonary venous pressure
84
What is postcapillary pulmonary hypertension
Due to increased pulmonary venous pressure, typically from left heart disease causing left atrial hypertension
85
Systolic pulmonary artery pressure can be estimated from the tricuspid regurgitation velocity by which equation
- Simplified bernoulli equation
- Pressure gradient = 4x velocity (m/s)^2
86
What are the 6 groups of underlying cause for PHT
* Pulmonary arterial hypertension (PAH)
* Left heart disease
* Respiratory disease/hypoxia
* Pulmonary thrombotic or thromboembolic disease
* Parasitic disease (heartworm or Angiostrongylus)
* Multifactorial or unclear mechanisms
