Respiratory Flashcards
1
Q
If a patient were to develop a tension pneumothorax during HBOT, when does it most likely to happen?
A
At the decompression phase
2
Q
True or False: Patient with marked respiratory acidosis can become hypoxemic too.
A
True
3
Q
What is the definition of hypoxemia
A
PaO2 < 80 mmHg
4
Q
List 4 different kinds of hemoglobins.
A
Oxygenated hemoglobin
Deoxygenated hemoglobin
Methemoglobin
Carboxyhemoglobin
Sulfhemoglobin
5
Q
What is the two wavelengths of light on pulse oximeter?
A
940 nm (infrared)
660 nm (red)
6
Q
How many percentage of total lung elasticity does tissue elastic forces contribute (to collapse the lung) and how many does fluid-air surface tension forces contribute?
A
Tissue elastic forces 1/3
Fluid-air surface tension forces 2/3
7
Q
What cells secrete surfactant?
A
Type II alveolar epithelial cells (10% of the surface area of the alveoli)
8
Q
What are the main components of surfactant?
A
Phospholipid dipalmitoyl phosphatidylcholine
Surfactant apoproteins
Calcium ions
9
Q
True or False: Alveolar pressure caused by surface tension is directly related to alveolar radius.
A
False
Alveolar pressure caused by surface tension Is INVERSELY related to alveolar radius → the smaller the alveolar, the greater the alveolar pressure caused by the surface tension
10
Q
What are the three main components of the work of inspiration?
A
1) Compliance work/elastic work - work that required to expand the lungs against the lung and chest elastic forces
2) Tissue resistance work - work that required to overcome the viscosity of the lung and chest wall structures
3) Airway resistance work - work that required to overcome airway resistance to movement of air in
11
Q
Fill out the blank.
A
12
Q
What is the remaining of the air after a normal expiration call?
A
Functional residual capacity
*** NOT RESIDUAL VOLUME
13
Q
Define anatomic dead space and physiological dead space.
A
Anatomic dead space: the total volume of the conducting airway (the area where normally gas exchange does not occur)
Physiological dead space: anatomic dead space + alveolar dead space
14
Q
What is the formula for minute ventilation?
A
Minute ventilation = tidal volume x respiratory rate
15
Q
The respiratory system has two circulation. What are they called and where are they?
A
High-pressure, low-flow circulation
- systemic arterial blood to the trachea, bronchia tree, connecting tissue of the lung
Low-pressure, high-flow circulation
- venous blood that enters the pulmonary arteries and to the alveolar capillary to gas exchange
16
Q
How does hypoxia affect the systemic vessels and pulmonary vessels?
A
Systemic vessels - vasodilation
Pulmonary vessels - vasoconstriction
17
Q
What is the definition of terminal bronchioles?
A
The smallest airways without alveoli.
18
Q
What is the definition of respiratory bronchioles?
A
divided from terminal bronchioles, which have occasional alveoli budding from their walls
19
Q
Which of the following volume can spirometer measure?
1) Total lung capacity
2) Tidal volume
3) Residual volume
4) Functional residual capacity
A
2) Tidal volume
20
Q
What are the two methods to measure FRC?
A
Helium dilution
Whole body plethysmography
21
Q
What does the alveolar ventilation mean?
A
The amount of air that is available for gas exchange
22
Q
If you want to increase alveolar ventilation, which way is more effective, increasing tidal volume or respiratory frequency?
A
Increase tidal volume, because anatomic dead space is fixed
23
Q
What is the alveolar ventilation equation?
A
24
Q
Respiratory laboratory commonly use Bohr’s method to measure physiology dead space. What is the equation?
A
25
What is normal physiological dead space percentage?
0.2 - 0.35
26
When the patient has pulmonary disease, how will the relationship between anatomic dead space and physiological dead space change?
Physiological dead space will be bigger than the anatomic dead space
27
How long does a red blood cell usually stay in the pulmonary capillary?
0.75 seconds
28
Explain what is diffusion limited and perfusion limited, and name an example for each of them
Diffusion limited
- The gas that enter the capillary can be rapidly picked up/bind to the red blood cells due to high affinity → minimal change in partial pressure → minimal back pressure to slow it down → the rate of diffusion depends on the property of the blood gas barrier
- Example: CO
Perfusion limited
- The gas that enter the capillary is barely bound to RBCs due to very low affinity → partial pressure rapidly increase → the faster the blood flow is, the more gas that can enter the capillary
- Example: N2O
29
Is O2 diffusion limited or perfusion limited? Why?
A combination of both
Under normal resting condition, O2 is already partially saturated in the blood due to mixed venous blood. O2 usually reach fully saturated state when the RBC is at 1/3 way of the capillary → perfusion limited
* If the patient's blood gas barrier is abnormal and the oxygen cannot reach fully saturated state when the RBC is at the end of the capillary → perfusion limited + diffusion limited
30
Which gas is ideal for diffusion capacity measurement. Why?
Carbon monoxide
Because the gas is purely diffusion limited
31
Describe the route oxygen reach RBC in the long.
Surfactant → alveolar epithelium → alveolar epithelium basement membrane → interstitial space → capillary basement membrane → capillary endothelium → plasma → red blood cell
32
What is normal systolic, diastolic and mean pulmonary arterial pressure? What about artery?
Pulmonary artery: 25/8 (15) mmHg
Artery: 120/80 (100) mmHg
33
Pulmonary vascular resistance is only ____ that of the systemic circulation. What is the number?
1/10
34
What are the two mechanisms of decreased pulmonary vascular resistance when pulmonary vessels pressure increases?
1) Distension
- Predominant when pulmonary pressure is already high
2) Recruitment
- Main mechanism for pulmonary artery
- Open up more closed capillaries
35
How does the lung volume affect the pulmonary capillary and extra-alveolar vessels resistances?
When the lung volume is very small
- Extra-alveolar vessels become narrow/collapse (pull from the parenchyma <<< vascular smooth muscle tone) → increased resistance
- Pulmonary capillary remains open
When the lung volume is very big
- Extra-alveolar vessels are pulled open by the lung parenchyma → decreased resistance
- Pulmonary capillary are collapsed because alveolar pressure >>> capillary pressure
* There is a sweet spot when the total resistance is the lowest
36
True or False: West's zone 1 does not occur in healthy individual.
True
* It can happen when patient's hypotensive or alveolar pressure increased significantly
37
What is West Zone 4? When will you see it?
When the interstitial pressure is higher than alveolar pressure and pulmonary venous pressure (but no pulmonary arterial pressure)
Pa > Pinterstitial > Pv > PA
Pulmonary edema at the base of the lung
38
What determines the blood flow in West Zone 2 and Zone 3?
Zone 2: gradient between alveolar and pulmonary arterial pressure
Zone 3: gradient between pulmonary arterial and pulmonary venous pressure
39
What determines the blood flow in West Zone 2 and Zone 3?
Zone 2: gradient between alveolar and pulmonary arterial pressure
Zone 3: gradient between pulmonary arterial and pulmonary venous pressure
40
True or False: Hypoxemia can cause pulmonary vasoconstriction.
False
Alveolar hypoxia (not blood!) cause vessel wall hypoxia → vasoconstriction
41
What is the cut-off for alveolar hypoxia induced-vasoconstriction?
Alveolar PO2 < 70 mmHg
42
What is the proposed mechanism of alveolar hypoxia induced-vasoconstriction?
Inhibition of voltage-gated K+ channel → Decrease the efficiency of Na/K-ATPase → increase intracellular Na → more Na to exchange for Ca (Na/Ca channel) → Increase Ca inflow → vasoconstriction
43
What are the two substances that ACE can convert/inactivate?
Angiotensin I
Bradykinin
44
List 5 substances that can be inactivated when they enter the pulmonary circulation
Bradykinin
Serotonin
Norepinephrine
Leukotriene
Prostaglandin E2 and F2𝜶
45
What is the most abundant immunoglobulin in the bronchial secretion?
IgA
46
What is the equation for A-a gradient?
A-a gradient = PAO2 - PaO2 = [FiO2x(Patm-PH2O) - PaCO2/0.8] - PaO2
Normal: < 10
* Normal PH2O = 47 mmHg
47
What is the formula to calculate pulmonary shunt from mixed venous blood?
48
What is normal percentage of pulmonary shunt?
2%
49
True or False: Ventilation and blood flow both increase from top to bottom of the lungs. Blood flow increase more rapidly than ventilation.
True
50
True or False: The ventilaiton perfusion ratio decreases from the top to the bottom of the lung.
True
51
Is the pH higher at the top or the bottom of the lung?
Higher at the top of the lung
52
True or False: The respiratory exchange ratio (CO2 output/O2 uptake) is higher at the apex than at the base.
True
53
Why the increased minute ventilation to a lung with V-Q inequality is usually effective at reducing the Paco2, but much less effective at increasing arterial Pao2?
Because CO2 is more diffusible than O2
54
What is Henry's Law?
The amount of gas dissolved in the liquid/blood is proportional to its partial pressure
55
Does presence of COHb shift oxygen-hemoglobin dissociation curve to the right or left?
Left (increased O2 and hemoglobin binding)
56
Describe Bohr effect and Haldane effect.
Bohr effect: at the peripheral tissue, the increased partial pressure of CO2 and H+ decrease the affinity of hemoglobin affinity to O2 → facilitates unloading of O2
Haldane effect: at the lung, the increased partial pressure of O2 decrease the affinity of hemoglobin affinity to CO2 → facilitates unloading of CO2
* Deoxygenated hemoglobins have higher affinity to CO2
57
Which state of hemoglobin has lower affinity to oxygen, the tense state (T-state) or relax state (R-state)?
T-state
* It becomes more relaxed as more and more oxygen binds to the hemoglobin
58
The CO2-hemoglobin dissociation curve will shift to the left or right as SO2 increases?
Shift to the right (higher O2 → decrease hemoglobin affinity to CO2)
59
What are the four types of tissue hypoxia?
1) Hypoxic hypoxia
2) Anemic hypoxia
3) Circulatory hypoxia
4) Histotoxic hypoxia
60
On the pressure volume curve, the inspiration and expiration are not overlapped. What is it called and why?
Hysteresis
pressure required for inspiration is greater than the pressure required for expiration because of the surface tension and surfactant, as well as the alveolar recruitment and elastic property of the lung.
61
What is the definition of compliance?
The volume change per unit pressure change
62
List 2 causes of decreased lung compliance and 2 causes of increased lung compliance.
Decreased compliance: lung fibrosis, pulmonary edema, atelectasis
Increased compliance: pulmonary emphysema, normal aging lung
63
List 3 benefits of surfactant.
1) Reduce surface tension of the alveoli
2) Decrease work of breathing
3) Keep the lung dry
4) Promote stability of alveoli
64
Compared to the apex and base of the lungs, which one has better compliance and ventilation?
Base of the lungs
Because the resting volume is smaller and the change of volume during inspiration is bigger (expanding pressure is smaller at the base due to smaller transmural pressure due to the weight of the lung)
65
True or False: Functional residual capacity (FRC) is the equilibrium volume when the elastic recoil of the lung is balanced by the normal tendency for the chest wall to spring out.
True
66
True or False: The normal intrapleural pressure is 0.
False
-5 cmH2O (because of elastic recoil of the lung)
67
In the entire pulmonary system, where is the major site of airway resistance from?
Medium-sized bronchi
68
What does 0ABCD, ABCE, and 0AECD represent?
0ABCD represents work of breathing
ABCE represents the work to overcome the airway and tissue resistance
0AECD represents the work to overcome the elastic force
69
What is the equate for work of breathing?
WOB = pressure x volume
70
Where does breathing center locate?
Brainstem (pons, medulla)
71
Where is the normal respiratory rhythm generated?
Medullary respiratory center, Pre-Botzinger complex
72
What does apneustic center and pneumotaxic center do?
Apneustic center: excite the inspiratory center
Pneumotaxic center: inhibit inspiratory
73
There are two respiratory group (dorsal and ventral) in the medullary respiratory center. Which controls inspiration and which controls expiration?
Inspiration: Dorsal respiratory center
Expiration: Ventral respiratory center
74
How does PCO2 regulate the respiration?
By changing the pH of CSF
Blood Pco2 rises ➜ CO2 diffuses into the CSF from the cerebral blood vessels ➜ liberates H+ ions that stimulate the chemoreceptors ➜ hyperventilation ➜ blood Pco2 reduces and therefore in the CSF
75
Where is the central chemoreceptors?
Ventral surface of the medulla
76
What change does the peripheral chemoreceptors detect?
Change in PO2, pH and PCO2
77
What is the effect when the pulmonary stretch receptors are activated (during lung expansion)?
Slow down the respiratory frequency (because the lung needs longer expiration time)
78
Where are the pulmonary stretch receptors and irritant receptors?
Pulmonary stretch receptors: within airway smooth muscles
Irritant receptors: between airway epithelial cells
79
Where are the J receptors (Juxtacapillary receptors) and what is its function?
In the alveolar walls (close to the capillary)
When the pulmonary capillaries are enlarged or there is increased interstitial fluid in the alveolar wall → J receptors are stimulated → signals are transmitted through non-myelinated C fibers → increased respiratory rate
80
True or False: Decreased PO2 can stimulate both central and peripheral chemoreceptors and cause increased ventilation.
False
Only peripheral chemoreceptors
81
Why patients with chronic respiratory disease lose their adequate response to elevated PCO2?
Renal compensation → the change in pH is abolished
* In this case, hypoxemia becomes the main stimulus to ventilate
82
Does the pH change mainly stimulate the central or peripheral receptors?
Peripheral chemoreceptors
83
Draw and describe the three bottle system.
Pressure for suction: 10-20 cmH2O
84
What is the FiO2 when the flow-by oxygen is provided at 2-3 L/min?
25 - 40%
85
what FiO2 can be provided when the nasal oxygen is provided at 50-150 ml/kg/min?
30 - 70%
86
What is the landmark to place a nasopharyngeal catheter?
From the nose to the mandibular ramus
87
What is the landmark to place a nasal oxygen catheter?
From the nose to the lateral canthus
88
To avoid oxygen toxicity, a FiO2 of higher than 50% should not be administered more than what?
24-72 hours
89
What is the main drive for oxygen diffusion to the tissue, PaO2 or SaO2?
PaO2
90
True or False: The higher the PaO2, the higher the SaO2.
False
When the PaO2 is below 100 mmHg, the statement is true, but when the PaO2 is above 100 mmHg, the SaO2 will always show as 100% no matter how high PaO2 is.
91
What are the correlation of the following PaO2 and SaO2: SaO2 = 100%, 99%, 98%, 95%, 90%.
92
What are the cause of hypoxemia?
Low inspired oxygen
Global hypoventilation
Venous admixture
- Low V/Q regions
- Diffusion impairment
- Atelectasis
- Right-to-left shunt
Very low venous oxygen content
93
What is the relationship between PaCO2 and ETCO2?
ETCO2 is about 5mmHg lower than PaCO2
94
What is the relationship between PaCO2 and CVCO2 (central venous)
CVCO2 is about 5mmHg higher than PaCO2
95
What is the normal gas composition in alveoli at sea level room temperature?
N2 560 mmHg
O2 105 mmHg
CO2 40 mmHg
H2O 50 mmHg (47 mmHg)
96
True or False: Hypoventilation is a cause of hypoxemia in patient’s breathing room air but not in patients breathing enriched oxygen mixtures.
True
97
Theoretically, which V/Q condition will decrease PaO2?
1) Ventilated but unperfused lung units (e.g. PTE)
2) High V/Q (e.g. hypovolemia)
3) No ventilated but perfused lung areas (e.g. physiological shunt)
3)
98
When breathing room air at sea level, what is normal sum of PaO2 and PaCO2?
120
PaO2 = 80 mmHg
PaCO2 = 40 mmHg
* If the added value is not 120 → presence of venous admixture
99
What is one of the big limitations of using P/F ratio to evaluate lung function at room air?
The P/F ratio can be very misleading when used at 21% inspired oxygen concentrations if PaCO2 values are elevated. PaCO2 values have been ignored in this calculation, but when breathing room air, changes in PaCO2 can have a significant impact on PaO2.
100
What are the 3 dead space in the respiratory system?
Anatomic: upper airway, trachea
Alveolar
Physiologic: anatomic + alveolar dead space
Apparatus: dead space resulting from devices placed between the ET tube and the Y-piece of the breathing circuit (e.g. the ET tube that is too long)
101
True or False: Physiologic dead space is approximately the same as anatomic dead space when the lung is normal.
True
102
What is the relationship between PvCO2 and PaCO2?
PvCO2 is about 3-6 mmHg higher than PaCO2
103
Why the patient with C3-C5 spinal cord injury may be unable to breath spontaneously?
The nerve fibers mediating inspiration converge on the phrenic motor neurons in the ventral horns from C3 to C5.
104
Define Hering-Breuer inflation reflex.
When the alveolar is inflated, the pulmonary stretch receptors will be stimulated and send signals through vagus nerve to the apneustic center in lower pons → slowing of respiratory frequency by increasing expiratory time
105
True or False: Arterial baroreceptors can affect the breathing.
True
A large decrease in arterial blood pressure causes hyperventilation, whereas a large increase in arterial blood pressure causes respiratory depression.
106
What are the four big categories for the differential of hypercapnea?
1) Hypoventilation
2) Increased inspired CO2
3) Increased CO2 production with a fixed minute ventilation
4) Increased dead space ventilation
107
When there is decreased tissue perfusion or decreased cardiac output, how will the PvCO2-PaCO2 gradient change, increase or decrease? Why?
Increased
Decrease tissue perfusion → increased tissue CO2 production due to increased H+ production secondary to lactate formation and hydrolysis of ATP
108
What is the ETCO2-PaCO2 gradient used to evaluation? What does the increased gradient mean?
Dead space ventilation
Increased gradient means increased physiological dead space (alveolar dead space?) either increased V/Q or decreased V/Q
109
What are the three mechanisms for oxygen-induced hypercapnea in patient with chronic hypoventilation and acute hypoxemia?
1) depress the hypoxemic-driven peripheral chemoreceptor stimulation → depress respiratory drive → worsening of hypoventilation
2) reverse the hypoxemic-induced pulmonary vasoconstriction → worsening the V/Q ratio (increased perfusion without concomitant increased ventilation → worsening of hypercapnea
3) When the hypoxemia is corrected, the increased partial pressure of O2 will decrease the affinity of Hb to CO2 → release more CO2 from the Hb → worsening of hypercapnea
110
What are the pros and cons of mainstream and sidestream capnography?
Mainstream
- Pros: near real-time waveform
- Cons: device is bulky, increase apparatus dead space
Sidestream
- Pros: less bulky, less dead space, more comfortable
- Cons: delayed waveform, dilutional effect from other gas
111
List 4 respiratory stimulants.
1) Doxapram
2) Caffeine
3) Progesterone
4) Aminophylline/theophylline
112
During inspiration, which part of the trachea has higher tendency to collapse?
Trachea rostral to the thoracic inlet
113
Describe paradoxical laryngeal movement.
Inward movement of the arytenoids during inspiration.
114
In normal dogs, where do most of the airway resistance come from?
Nose
115
What are the anatomic abnormalities of BOAS?
Elongated soft palates, stenotic nares, tracheal hypoplasia
Everted laryngeal saccules, tonsillar eversion, laryngeal collapse, chronic GI signs
116
For cats with middle ear polyps, what is the name of the surgical management? What is the most common complications?
Ventral bulla osteotomy (VBO)
Vestibular signs (~50%, can last for 4 weeks)
117
True or False: The split cartilage anastomosis technique results in better alignment and apposition of the tracheal ends and less long- term luminal stenosis than the annular ligament and cartilage technique.
True
118
How much percentage of trachea can be resected in a mature dog?
25-50%
119
For the intrathoracic tracheal tear repair, which side should the thoracotomy be performed?
Right
120
What is the recommended ET tube cuff pressure?
20 - 30 cmH2O
121
Does asthma cause increased or decreased FRC?
Increased (due to air-trapping)
122
What is the most common parasite causing allergic response in canine lungs?
Toxocara canis
123
What are the two main pathophysiologic forms of pulmonary edema?
High-pressure edema
Increased-permeability edema
124
Explain the blast theory in neurogenic pulmonary edema.
The result of two mechanisms: high hydrostatic pressure + pulmonary endothelial injury due to sympathetic surge
After a massive, neuronal event, the sympathetic nerve system is activated and it can cause high-pressure edema due to increased capillary hydrostatic pressure. The high hydrostatic pressure & sympathetic nerve system activation also cause the barotrauma to the capillary endothelium, which leads to the formation of increased-permeability edema.
125
List 3 proposed mechanisms for reexpansion edema.
1) Decreased surfactant production
2) Mechanical force leading to pulmonary parenchyma injury
3) Reperfusion injury
4)
126
True or False: The most common clinical signs in cats with infectious pneumonia are fever and coughing.
False
Cats rarely cough, the most common clinical signs is dyspnea
127
What is the MOA of NAC in clearing the mucus?
breakdown of the disulfide bonds
128
What is the cutoff of the particles size to be able to enter the alveoli?
3 um
129
Explain the biphasic pathogenesis of aspiration pneumonitis.
1-2 hours after aspiration
Initial insult is caused by direct chemical irritation → damage of bronchial epithelium and alveolar endothelium → the acid aspirate also stimulates tracheobronchial substance P–immunoreactive neurons → induces tachykinin neuropeptide release → neurogenic inflammation, bronchoconstriction, vasodilation, increased vascular permeability
4-6 hours after aspiration
Inflammatory mediator cascades producing neutrophil chemotaxis (IL-8, TNF-α,17 and macrophage inflammatory protein 2), sequestration, and subsequent increased permeability edema
130
Why is bronchodilator not recommended in dogs with aspiration pneumonia?
It cause inotropic and vasodilation → potentially increase V/Q mismatch
131
In ARDS/ALI, how will the pulmonary compliance change?
Decreased compliance **Hallmark of ARDS**
132
In human, how many percentage of pulmonary contusion volume predicts the need for mechanical ventilation?
> 20%
133
What is the primary reason for PTE-induced hypoxemia?
High V/Q mismatch
134
List 5 changes in hemodynamics & pulmonary gas exchange that can be observed in PTE.
1) Right sided pressure overload
2) Hypoxemia (due to dead space ventilation)
3) pulmonary hypertension
4) Decreased cardiac output
5) Hypotension
135
When you need to put a patient with flail chest on lateral recumbency, which side should be down?
The side with the flail chest down
136
Where does the segmental intercostal nerves leave?
C6 - T2
137
What is the proposed pathophysiology of acute idiopathic polyradiculoneuritis?
Immune-mediated demyelination and degeneration of axons of the ventral roots and spinal nerves
* Decreased segmental reflexes, normal sensation, hyperesthetic
* Treatment: supportive care (steroid doesn't seem to help)
* usually take 3+ weeks to recover
138
Which type of botulism toxin is the primary one in dogs?
Type C toxin
139
What is the pathophysiology of botulism?
Botulinum toxin blocks release of ACh at the pre-synaptic terminal of skeletal muscle and cholinergic autonomic synapsis
* The toxin cause irreversible enzymatic cleavage of Soluble N-ethylmaleimide-sensitive factor activating protein receptor (SNARE) proteins. SNARE proteins are essential for “docking” synaptic ACh vesicles to pre-synaptic membranes, allowing release of ACh into the synaptic cleft.
140
In patient with botulism or MG, which antibiotic should be avoided and why?
Aminoglycoside, because it can prolong or lead to complete NM blockage
MOA: interfere with Ca movements through the Ca channels of the membrane of the nerve-endings → inhibits acetylcholine release at the synaptic cleft
141
Which one is the post-synaptic NM junctional disease?
1) Myasthenia gravis
2) Botulism
3) Tick paralysis
4) Elapid Snake Envenomation
1)
* Some 4) are post-synaptic too
142
What is normal pleural space pressure?
-5 cmH2O
143
Define tension pneumothorax
Air leaks into the thoracic cavity but cannot exit fully (one way valve at the leakage site)
144
When do hypoxemia become the primary drive for ventilation?
When PaO2 < 50 mmHg
145
Submersion in ice-cold water (<5°C [41°F]) increases the chances of survival because of the diving reflex. Explain diving reflex.
It is a reflex mediated by trigeminal nerve. When the animal's face touch cold water, the trigeminal nerve will send signal to the CNS and cause bradycardia, hypertension, and preferential shunting of blood to the cerebral and coronary circulations → protect the brain and heart from hypoxia-induced injury
The cold temperature also decreased the metabolic rate.
146
In smoke inhalation, what chemical can cause histotoxic hypoxia?
Hydrogen cyanide (HCN)
147
List 3 mechanism of smoke inhalation causing airway obstruction.
1) thermal injury causing laryngeal edema
2) bronchoconstriction from irritant gases and Particulate Matter
3) Increased bronchial secretion and edema fluid
148
What is the CO in room air and with 100% oxygen supplementation?
Room air: 250 min
100% Oxygen: 26-148 min
149
What is the treatment for cyanide toxicity?
Hydroxocobalamin
*Bind to cyanide to form cyanocobalamin (vitamin B12)
150
Fill out A to E.
A: Respiratory baseline
B: Expiratory upstroke
C: Alveolar plateau
D: EtCO2
E: Inspiratory downstroke
151
How small should the aerosol particles be to reach the small bronchioles and alveoli?
The aerodynamic equivalent diameter (AED) should be < 5 𝜇m
152
There are two types of albuterols on the market - levalbuterol and racemic mixture. Which one is recommended for cats and dogs? Why?
levalbuterol
The main components is R-albuterol, which is an effective bronchodialtor. Racemic mixture has both R-albuterol and S-albuterol. The S-albuterol is proinflammatory and can cause bronchoconstriction.
153
What is Bordetella bronchiseptica?
Gram negative, obligate aerobic coccobacillus
154
What dose this EtCO2 tell you?
Bronchoconstriction/Asthma
155
What does this EtCO2 tell you?
Rebreathing
156
What does this EtCO2 tell you?
Patient is breathing spontaneously
157
What does this EtCO2 tell you?
Cardiac oscillation
158
True or False: HFNO can increase FRC.
True
It can provide some degree of PEEP and increase FRC → improve compliance, decrease V/Q mismatch
159
True or False: The alveolar oxygen concentration will be determined by the ratio of oxygen gas flow to minute volume.
True
160
What is the initial patient's flow rate for HFNO?
calculate patient's minute ventilation (estimated tidal volume = 10-15 ml/kg)
161
Under normal condition, what is the proportion of the expired tidal volume is re-breathed?
1/3
162
List 10 proposed etiology for laryngeal paralysis.
1) Congenital
2) GOLPP
3) Neoplasia
4) Trauma
5) Toxin (e.g. organophosphate, lead)
6) Hypothyroidism
7) Iatrogenic (e.g. previous surgery, ventral slot)
8) Immune-mediated
9) Infectious disease
10) SLE
163
What is the surgery called for laryngeal paralysis?
unilateral arytenoid lateralization
164
What is the landmark for nasotracheal tube?
From the nose to the 5th intercostal space
* This length should place the tube’s tip just cranial to the tracheal bifurcation.
165
True or False: The diameter of the tracheostomy tube should be the same as the inner diameter of the trachea.
False
It should be 1/2-1/3 of the tracheal diameter to minimize iatrogenic tracheal trauma and decrease the incidence of post-intubation stenosis.
166
What is the ideal tracheostomy tube length?
6-7 tracheal rings down from the insertion site
167
Describe how to perform a temporary tracheostomy.
1. Collect necessary supplies.
2. Anesthetize and orotracheally intubate the patient with a cuffed ET tube.
3. Position the animal in dorsal recumbence with a towel rolled under the neck. Clip and aseptically prepare a large surgical field on the ventral cervical surface.
4. Perform hand hygiene, and don cap, mask, and sterile gloves.
5. Isolate the prepared surgical site with a barrier drape.
6. Make a ventral midline cervical skin incision just caudal to the cricoid cartilage for a distance of approximately 3 to 4cm.
7. Apply a self-retaining retractor (e.g. Gelpi) to hold open the skin edges and clear just enough subcutaneous tissue to identify the midline
division of the sternohyoideus muscles.
8. Using Metzenbaum scissors, bluntly separate the sternohyoideus muscles on the midline, taking care to avoid the thyroidea caudalis vein on the midline between these two muscles. Retract the thyroidea caudalis vein to one side along with one of
the sternohyoideus muscles.
9. Reposition the self-retaining retractors on the sternohyoideus muscles to expose the trachea and clear the loose fascia away at the proposed tracheotomy site. Application of a second self-retaining retractor at a right angle to the original retractor to retract the skin in a craniocaudal direction enhances exposure.
10. Using a scalpel blade, incise the interannular ligament between the 2nd and 3rd tracheal rings. Do not incise the interannular ligament beyond 50% of the tracheal circumference.
11. Place stay sutures around the second and third tracheal rings, knot the sutures to create large suture loops, and tag the suture strands with mosquito hemostatic forceps.
12. Use the stay sutures to manipulate the interannular opening while the orotracheal tube is removed. Insert the tracheostomy tube with the obturator in place, and then quickly remove the obturator and replace it with an inner cannula.
13. Leave the stay sutures in place for postoperative nursing care manipulations.
14. Secure the tracheostomy tube by attaching umbilical tape to the flange eyelets and tying the tapes behind the neck.
15. Do not suture the tracheostomy wound unless the incision was made too large. In that case, place a few interrupted sutures in the subcutaneous tissue and/or skin to decrease the size of the wound, taking care not to make the wound too small.
16. Once the surgical procedure is completed, the area is gently cleaned and left uncovered for easy observation.
168
What are the three phases of ARDS?
Exudative
Proliferative
Fibrotic
169
Describe The Berlin Definition.
1) Onset: Within 7 days of the known insult or new or worsening of respiratory signs
2) Chest images: Bilateral opacities (no fully explained by nodules, effusion or lobar collapse)
3) Origin of edema: rule out cardiac failure or fluid overload (by echo)
4) Oxygenation
- Mild: 200 mmHg < PaO2/FiO2 ≤ 300 mmHg with PEEP or CPAP ≥ 5 cmH2O
- Moderate: 100 mmHg < PaO2/FiO2 ≤ 200 mmHg with PEEP or CPAP ≥ 5 cmH2O
- Severe: PaO2/FiO2 ≤ 100 mmHg with PEEP or CPAP ≥ 5 cmH2O
170
What is the characteristics of exudative phase of ARDS?
Protein-rich edema and eosinophilic hyaline membrane in the alveolar wall
171
List 5 risk factors for ARDS/ALI in veterinary medicine.
1) Sepsis
2) Inflammation
3) Infection
4) SIRS
5) Major trauma
- Long bone fractures
- Head injury
- Pulmonary contusion
6) Multiple transfusion
7) Smoke inhalation
8) Near drowning
9) Aspiration of stomach content
* Neoplasia is not one of them
172
What is lung protective ventilation?
Low tidal volume: 4-8 ml/kg
High PEEP
Keep the target plateau pressure < 30 cmH2O
*Permissive hypercapnea
173
What is the most common clinical presentation of ARDS/ALD in veterinary medicine?
Refractory hopoxemia
174
Describe the definition of VetARDS/VetALI (5 points).
1. Onset: Acute onset (<72 hours) of respiratory distress at rest
2. Known risk factors
3. Evidences of pulmonary capillary leakage without increased capillary hydrostatic pressure (no evidence of cardiogenic edema)
- bilateral pulmonary infiltrates on TXR
- bilateral dependent density gradient on CT
- proteinaceous fluid within the conducting airway
- increased extravascular lung water
4. Inefficient gas exchange
- PaO2/FiO2 ratio WITHOUT PEEP or CPAP
≤ 300 mmHg (VetALI)
≤ 200 mmHg (VetARDS)
- Increased A-a gradient
- Increased dead space ventilation
5. Evidence of diffuse pulmonary inflammation (optional)
- TTW/BAL samples show neutrophilia
- TTW/BAL samples biomarkers show inflammation
- Molecular imaging (PET)
175
What are the three types of ventilator breaths?
1. Spontaneous
2. Assisted
3. Controlled
176
In patients with severe pulmonary disease, does the airway pressure need to be higher or lower on the ventilator setting? What about the volume?
Volume: usually benefit from lower volume
Pressure: usually need higher airway pressure (to be able to reach the tidal volume needed)
177
What is the common initial flow rate setting in mechanical ventilation?
40-60 L/min
178
What is an appropriate trigger?
flow change of 1-2 L/min
Airway pressure dropped 1-2 cmH2O
179
What is normal minute ventilation in small animals?
150-250 ml/kg
180
What are the three main indications for mechanical ventilation?
1. Severe hypoxemia despite oxygen therapy (PaO2 < 60 mmHg)
2. Severe hypoventilation (PaCO2 > 60 mmHg)
3. Respiratory fatigue
4. Severe hemodynamic compromise that is refractory to therapy → goal is to decrease oxygen consumption
181
What is the goal of mechanical ventilation?
Maintain normal arterial blood gas
PaCO2 35-50 mmHg
PaO2 80-120 mmHg
182
What is the equation of motion?
It is used to describe the force that drive ventilation
Pmuscle + Pvent = (Tidal volume/compliance) + (resistance x flow)
Pmuscle: pressure generated by the muscle
Pvent: pressure generated by the ventilator
Tidal volume/compliance: elastic load
Resistance x flow: resistant load
183
Which one is volume-control ventilation and which one is pressure-control ventilation?
A: Pressure-control
B: Volume-control
* Pressure-controlled → pressure is the same
* Volume-controlled → shark fin volume time scalar → flow stops once volume is reached
184
Fill in the blank: All the breaths delivered in assist-control ventilation are ________ in nature.
mandatory
185
Name two examples of continuous spontaneous ventilation.
CPAP (Continuous positive airway pressure)
PSA (Pressure support ventilation)
186
Describe the difference between assisted breath and supported breath.
Assisted breath: patient initiates the breath; machine provide entire inspiratory flow and terminates the cycle
Supported breath: patient initiates the breath and finishes the whole cycle; the machine support the patient with the inspiratory flow
187
List 2 possible complication from fast respiratory rate.
1) Auto-PEEP (air stacking)
2) Hypotension (decreased venous return)
188
List 5 adverse effects of PEEP.
1) Barotrauma
2) Decreased cardiac output due to decreased venous return
3) Compression of some alveolar capillaries → increased alveolar dead space
4) Increased pulmonary vascular resistance
5) Decreased LV compliance
189
What are the common setting for low and high airway pressure alarm? What are the common DDx for each of them?
Low Airway Pressure Alarm
- 5-10 cmH2O lower than peak airway pressure
- Circuit leak
High Airway Pressure Alarm
- 10 cmH2O higher than peak airway pressure
- Pneumothorax, ET tube kink or obstruction, patient-ventilator asynchrony
190
What are the common setting for low and high tidal volume alarm? What are the common DDx for each of them?
Low Tidal Volume Alarm
- 15% lower than the patient's tidal volume
- leak, disconnection of the circuit, drop in compliance
How Tidal Volume Alarm
- 20% higher than the patient's tidal volume
- Increased in compliance
191
Describe two ways to perform recruitment maneuver.
1) CPAP at 35-50 cmH2O for 20-40 secs
2) Pressure-supported ventilation with PEEP at 20 cmH2O and pressure above PEEP at 20 cmH2O for 1-3 minutes
192
Patient-ventilator asynchrony can be classified into two groups - patient related and equipment related. Name 5 examples for each.
Patient-related
- Hypoxemia
- Hypercapnea
- Hyperthermia
- Drug-induced panting
- Inadequate anesthesia depth
Equipment-related
- Circuit/Equipment leak
- Inappropriate trigger setting
- ET tube/circuit kink/obstructed
- Insufficient tidal volume
- Inspiratory time too long/short
193
Fill out the blank. During jet ventilation, distribution of ventilation and tidal volume depend more on ___________. Please fill in lung compliance or airway resistance.
Airway resistance
194
What are the indications of jet ventilation.
- When mechanical ventilation is needed but traditional positive pressure ventilation cannot be delivered (e.g. tracheal/laryngeal surgery, bronchoscopy, bronchial resection, laryngoscopy)
- Respiratory failure with circulatory shock
- If ventilation is required in patients with a tracheal lesion secondary to tracheostomy or prolonged intubation
195
What are 1-4 and a & c?
1: pressure used to overcome the circuit and airway
2: pressure used to expand the lung/alveoli
3: pressure throughout the expiratory phase
4: PEEP
a: peak inspiratory pressure (PIP)
c: plateau pressure
196
What is the equation for dynamic and static compliance? Which one is bigger? Why?
Dynamic compliance = tidal volume/(PIP-PEEP)
Static compliance = tidal volume/(Pplateau - PEEP)
Dynamic compliance < static compliance
Because dynamic compliance includes the pressure needed to overcome the airway and circuit
197
In this figure, which one indicates increased airway resistance, which one indicates decreased compliance?
A: increased airway resistance
B: decreased compliance
198
What can expiratory hold tell us?
Whether or not there is intrinsic PEEP (auto-PEEP).
199
List 2 differences of constant flow pattern and decelerating ramp flow pattern (in volume-control mode)
1) The PIP for constant flow pattern will be higher
2) The decelerating ramp flow allow fine-tuning of inspiratory time
200
This is a flow pattern for VC mode. What is the difference between b, c, d?
b: the inspiratory time is too short → flow asynchrony
c: optimal inspiratory time
d: the inspiratory time is too prolonged → increase risk of patient-ventilator dyssynchrony
201
What are the two ways to detect Auto-PEEP?
1) Expiratory hold
2) Check the flow scalar → if the expiratory flow does not return to baseline → Auto-PEEP
202
What does the change from purple to blue indicate?
Increased circuit/airway resistance
slightly decrease dynamic compliance
203
What does A and B indicates, respectively?
A: decreased dynamic compliance
B: increased dynamic compliance
204
What does LIP and UIP indicates, respectively?
LIP (lower inflection point): where the lung compliance suddenly increases due to opening of the collapsed conducting duct/alveoli
UIP (higher inflection point): where the lung compliance significantly decreases due to overdistension of alveoli
* PEEP should be set above LIP
205
What does scooping tell us?
Increased airway resistance
206
What does this flow-volume loop tell us?
Excessive airway secretion
207
What are the 4 phases that patient-ventilator dyssynchrony can happen?
1) Initiation/trigger phase
2) Flow delivery phase
3) Breath termination point
4) Expiratory phase
208
Trigger asynchrony is the most common form of PVD in human. What are the three types of trigger asynchrony?
1) Ineffective triggering
2) Auto-triggering
3) Double triggering
209
List 3 causes of double triggering.
1) Patient has higher ventilatory demand
2) Tidal volume is too small
3) Inspiratory time is too short
4) flow-cycle threshold set too high
210
What does premature cycling and delayed cycling mean?
Premature cycling: the patient is continuing to make inspiratory efforts at the time the ventilator cycles off
Delayed cycling: the patient initiates active expiratory efforts while the ventilator is continuing to deliver inspiratory flow
211
Why inhalant anesthetics should not be used for patient on mechanical ventilator?
It inhibits the hypoxic induced vasoconstriction → make hypoxemia worse
212
According to the current meta-analysis in human, does histamine-2 receptor antagonists a routine therapy for patients on mechanical ventilation?
No
higher rates of gastric colonization and VAP
213
What are the 6 criteria for patient to be able to enter the spontaneous breathing trial.
1) The primary disease has improved and stable
2) PaO2/FiO2 > 150-200 with FiO2 < 0.5
3) PEEP ≤ 5 cmH2O
4) Adequate respiratory drive
5) Hemodynamically stable
6) No evidence of organ failure
214
During the spontaneous breathing trial, does rapid-shallow breathing pattern or slow-deep breathing pattern has better change of weaning off?
slow-deep breathing pattern
215
What are the 9 criteria for failure of the spontaneous breathing test?
1) Tachypnea (RR > 50)
2) PaO2 < 60 mmHg or SpO2 < 90%
3) PaCO2 > 55 mmHg or PvCO2 > 60 mmHg or EtCO2 > 50 mmHg
4) Tidal volume < 7 ml/kg
5) Tachycardia
6) Hypertension
7) Hyperthermia or temp increase > 1C
8) Anxiety
9) Clinical judgement
216
What are the three weaning techniques?
Spontaneous breathing trial (with CPAP)
PSV
SIMV
217
Fill in the blank: When the inspiratory pressure is higher than _____ or tidal volume is higher than _____, pathologic change of the respiratory system can be observed.
30 cmH2O
40 ml/kg
218
List 5 ventilator-induced lung injury.
Volutrauma
Barotrauma
Pneumothorax
Oxygen toxicity
Atelectrauma
Biotrauma
219
What is the main risk factor of developing VAP?
Endotracheal intubation
220
What does the VAP refer to?
Ventilator-associated pneumonia
Pneumonia that arises more than 48 hours after endotracheal intubation that was not present at the time of intubation.
221
What are the two major pathologic mechanisms of VAP?
Biofilm formation within the endotracheal tube
Microaspiration pass the endotracheal tube cuff
222
What is the major type of bacteria for VAP?
Aerobic bacteria
223
For clinical diagnosis of VAP, what are the three criteria (2/3 need to be met)
1) Fever
2) Leukocytosis/leukopenia
3) Purulent airway secretions
224
Describe the criteria of VAP based on modified CDC National Healthcare Safety Network definition of pneumonia.
1) Presence of ET tube/tracheostomy at least 48 hours prior to the presence of clinical signs
2) Radiologic criteria: consolidation, cavitation, new or progressive and persistent pulmonary infiltrates
3) Systemic criteria: fever, leukocytosis/leukopenia
4) Pulmonary criteria (need 2): purulent airway discharge or increased secretion, worsening of gas exchange, new onset or worsening of coughing, dyspnea or tachypnea, crackles or bronchial breath sounds
225
True or False: To avoid VAP, the ventilator circuits should be change every 3 days.
False
Routine changing of the ventilator circuit should not occur unless contamination is noted.
226
Do brachycephalic dogs tend to be hypercoagulable or hypocoagulable?
hypercoagulable
Chronic hypoxia → inflammatory state
227
List 3 surgical interventions for BAOS.
1) Wedge nasoplasty (rhinoplasty)
2) Soft palate resection (staphylectomy)
3)E verted laryngeal saccules resection (ventriculectomy or sacculectomy)
228
True or False: Feline herpesvirus-1 is a double-stranded, enveloped DNA virus; Feline calcivirus is a single-stranded non-enveloped RNA virus.
True
229
Where does FHV-1 persists in during latent form?
Trigeminal ganglia
230
What are the three stages of laryngeal collapse?
Stage 1: laryngeal saccule eversion
Stage 2: loss of rigidity and collapse of the cuneiform processes of the arytenyoid cartilages
Stage 3: complete laryngeal collapse characterized by midline collapse of the corniculate processes
231
What is the most common tracheal neoplasia in dogs?
Osteochondroma
232
There are two types of sensory nerves for coughing - mechanical receptors and chemoreceptors. Where do they locate?
Mechanical receptors (myelinated afferent nerves): larynx, trachea, large bronchi
Chemoreceptors (C-fibers; unmyelinated axon): within all segments of the respiratory tree, including the larynx, carina, terminal bronchioles, and alveoli
233
What is the most common cause for hemoptysis in dogs?
Bacterial bronchopneumonia
234
What is the most common cause of feline bacterial bronchopneumonia?
Hematogenous spread
235
Where are the most common airway FB in dogs and cats?
Dogs: right bronchus
Cats: trachea or carina
236
What are the two most common mycosis in cats?
Cryptococcosis
Histoplasmosis
237
Why shouldn't NAC be used for nebulization?
Bronchoconstriction
Epithelial toxicity
238
How high of pulmonary venous pressure is sufficient to produce edema?
> 25 mmHg
239
Describe how to perform TTW.
1) Patient needs to be > 15kg
2) Patient is restrained in sternal recumbency with nose tipped dorsally
3) The ventral cervical area is clipped and aseptically cleaned
4) Local anesthesia (2 to 5 mg/kg, 2% lidocaine) is instilled intradermally and SC at the intended needle insertion site
5) A stab incision is made through the skin using a #11 blade at that site to facilitate passage of a sterile 14-gauge needle through the cricothyroid ligament.
6) Measure the insertion site to 4th ribs
7) Inserting a sterile 3.5-French red rubber or polypropylene catheter through the needle
8) Inject sterile saline 0.5 to 5 mL/kg per aliquot and aspirate when patient coughs
9) After removal of the catheter and needle from the trachea, the area is covered with a sterile, nonadherent gauze sponge and lightly bandaged
240
How does furosemide reach the NAK2Cl transporters?
Furosemide is secreted from the blood into the tubule lumen using an organic ion transporter located in the proximal convoluted tubule.
The efficacy of this process is regulated by renal perfusion, competition by other organic anions, such as NSAIDs, and the degree to which furosemide is bound to albumin in the circulation.
241
List 3 conditions that may interfere with furosemide's efficacy.
1) Hypoalbuminemia
2) Concurrent use of NSAIDs
3) Poor cardiac output
242
What is Kussmaul breathing?
Kussmaul breathing can be seen with severe metabolic acidosis and is defined as an extremely deep, rapid breathing pattern associated with hypocapnia
243
True or False: Animals with neurogenic pulmonary edema due to upper airway obstruction and seizures appear to have worse outcomes compared to NPE secondary to head trauma or electrocution.
True
244
What are the following physiologic changes will not be observed in diving in room temperature water?
1) Diuresis
2) Natriuresis
3) Kaliuresis
4) Increased work of breathing
5) Decreased cardiac output
5)
* Cardiac output increases
245
Does hypothermia increase or decrease antidiuretic hormone production?
Decreased → patient becomes polyuric
246
List 5 complications from submersion injury.
1) Hypoxemia
2) Aspiration pneumonitis
3) Arrhythmias
4) Metabolic acidosis
5) Neurological signs
247
In patient with submersion injury and hypothermia, when should the active warming stop?
Active rewarming should stop when core temperature reaches 37 °C (98.6 F) to prevent rebound pyrexia
248
What does Westermark sign indicate?
PTE
* Areas of relative oligemia secondary to decreased caliber of regional pulmonary arteries
249
When pleurodesis is used to treat spontaneous pneumothorax, how many ml of blood is usually used in total?
5-10 ml/kg
250
How many ml/kg of pleural effusion in dogs and cats will make them clinical?
Dog: 30-60 ml/kg
Cat: 20 ml/kg
251
Describe tracheostomy tube management.
1) Nebulization & airway humidification 10-15 min q4-6 hours
- Postural drainage and coupage (percussion) after
2) Clean the skin around the tracheostomy site with diluted chx (0.05%)
3) Check the tube ties
4) Tracheostomy tube suctioning
- Preoxygenation
- The entire suctioning procedure should be completed in less than 15 seconds
- No suction after eating
5) Tracheostomy tube cleaning
- q4-6 hours
- Replace the inner piece
6) Change the entire tracheostomy tube every 24 hours
252
Define "pendelluft."
it is a phenomenon describing the gas movement between lung regions with different compliances and airway resistance.
253
How to calculate driving pressure?
Driving pressure = Pplateau - PEEP
254
Where is the air emboli absorbed?
Lung
255
Fill out the blank: In dogs, clinical air embolism occurs in 50% of animals when _____ ml/kg/min of air (consisting of primarily nitrogen, an insoluble gas) is infused
0.35
