Respiratory Quiz #1 Flashcards
(113 cards)
1
Q
Identify clinical significance of the dimensions of the trachea and bronchi.
A
Tracheal dimensions- 11-13 cm long
Right Mainstem Bronchus
>1-2.5 cm from carina
>25 degrees off trachea
>1.6 cm width
Left Mainstem Bronchus
>5 cm from carina
>45 degrees off trachea
>1.3 cm width
2
Q
List 3 factors affecting upper airway tone
A
- Upper airway muscles can be affected by anesthesia and decreasing airway diameter
- Sleep? Causing sleep apnea!?
- muscles of pharynx and larynx control upper airway resistance
- muscles can be affected by anesthesia
- larynx has poor lymphatic drainage and is prone to edema
3
Q
Identify the three areas from teeth to bronchi with the smallest cross-sectional area.
A
- Incisors
- Oropharynx
- Glottis
4
Q
Describe the innervation of the tongue.
A
Glossopharyngeal(CN#9) innervates posterior 1/3
Trigeminal/Lingual(CN#5) innervates the anterior 2/3
- Lingual (part of CN V) = anterior 2/3 of tongue
- Glossopharyngeal (CN IX) = posterior 1/3 of tongue
5
Q
Describe the anatomy of the laryngeal cavity and vocal cords.
A
- Larynx extends from epiglottis to cricoid
- Inlet of larynx formed by upper border epiglottis cartilage, aryepiglottic folds and arytenoid cartilage
- Inside the laryngeal cavity are the vestibular folds (false cords); just lateral to the true vocal cords
- True vocal cords = attach anteriorly to thyroid and posteriorly to the arytenoids
- Larynx has poor lymphatic drainage → prone to edema
- Triangular fissure is the glottic opening between vocal cords
6
Q
Identify which laryngeal muscles abduct, adduct and regulate tension of the vocal cords.
A
Posterior cycoarytenoids-abduct
Lateroal crycoarytenoids-adduct
Cyricothyroid/Thyroarytenoid-Regulators of tension
7
Q
Identify the most narrow portion of the lower airway in adults.
A
Glottis is the narrowest part of the lower airway in adults
8
Q
Discuss the effects of recurrent laryngeal and superior laryngeal nerve damage.
A
- RECURRENT LARYNGEAL NERVE:
- SENSATION BELOW VOCAL CORDS - DAMAGE MAY CAUSE VOCAL CORD PALSY (INTERMEDIATE POSITION BETWEEN ABDUCTED AND ADDUCTED); “CAN’T TAKE A VERY DEEP BREATH”
- May occur from radial neck dissection, parotidectomy, redo thyroidectomy (distorted tissues); no NMB so nerve can be identified by Bovie with “NIMS” ETT, blue part goes in between vocal cords
- Right RLN damage– partial abduction, smaller flow
- Bilateral RLN damage– can’t talk, large problem with flow; have patient phonate “e” to rule out b/c that requires both vocal cords
- SUPERIOR LARYNGEAL NERVE:
- Sensation about the VC and to the cricothyroid
- STIMULATION MAY PROVOKE LARYNGOSPASM/FLACCID CORDS
9
Q
Describe the mucosa of the nasopharynx and trachea.
A
- Nasopharynx mucosa =
- Goblet cells: secrete 100 ml/day of mucous, aids in trapping inspired particles and prevents them from entering lungs
- Columnar cells: Contain 200-250 cilia, beat in waves toward oropharynx (mouth), at a rate of 2 cm/min; propels towards mouth so it can go into esophagus versus lungs
- Trachea mucosa=
- Pseudostratified columnar epithelium with cilia; goblet cells, serous cells, and specialized submucosal bronchial glands
- 200+ cilia per cell, 5-7 microns long
- Beat cephalad (head) direction toward oropharynx at 2 cm/minute; “keeps you from having an obstruction” in lungs
- Functions to humidify air and removes particles (cilia)
- All of these specialized cells can be interfered with
10
Q
Discuss the intrathoracic section of the trachea and its significance.
A
- Top half of trachea is extrathoracic, bottom half intrathoracic
- Extrathoraic is “not prone to things like PEEP but its prone to atmospheric limitation you can compress it (such as choking)”
11
Q
List four factors which slow mucociliary transport
A
- Cigarette smoke
- Dehydration
- Positive pressure ventilation
- Endotracheal suctioning? “May or may not”
- High inspired oxygen concentrations? “May or may not”
- Hypoxia
- Atmospheric pollutants
- General anesthesia
- Parasympatholytic drugs (glycopyrrolate); can also increase your dead space while trying to clear secretions
12
Q
Describe the anatomy of the trachea and main bronchi and clinical implications
A
trachea 11-13 cm long
RMS bronchus 1-2.5 cm long and wider than LMS bronchus; at a 25’ angle off trachea
aspirated objects generally go into the RMS bronchus > than the LMS bronchus
13
Q
Compare and contrast the conducting and respiratory zones of the tracheobronchial tree.
A
Generations 0-14 Conducting zone: no exchange here; anatomic deadspace 150ml (apart of TV/minute ventilation, but no gas exchange) • Trachea • left and right mainstem bronchi • Lobar bronchi • Segmental bronchi • Terminal bronchioles Generations 15-23 Respiratory zone: gas exchange occurs here (such large quantity you have a large surface area for gas exchange even though a smaller number of generations) • Respiratory bronchioles • Alveolar ducts and alveolar sacs
14
Q
Compare and contrast epithelium and cartilage in different generations of the lung.
A
GENERATION 0-1(TRACHEA AND MAIN BRONCHUS) HAVE COLUMNAR EPITHELIUM AND U-SHAPED CARTILAGE
GENERERATION 2-11 HAVE COLUMNAR CILIATED EPITHELIUM AND IRREGULARLY SHAPED CARTILAGE
GENERATION 12-23 HAVE NO CARTILAGE AND HAVE HAVE CUBOIDAL CELLS THAT MAKE UP THE EPITHELIUM AND ARE BETWEEN THE ALVEOLI
- Epithelium of respiratory tract: Pseudostratified (ciliated), Columnar (ciliated), Cuboidal in terminal bronchioles (no cilia)- by then the particles have to be tiny to get down there anyways so no cilia is needed
- Pseudostratified columnar ciliated epithelium from nasal cavity to bronchioles
- Cuboidal epithelium from bronchioles to alveolus
- Goblet cells produce mucous that lines all airways (increased in asthma and cystic fibrosis)
- Mucous is propelled forward by ciliated epithelial cells
- Other cells found in the respiratory epithelium include basal cells, mast cells, nonciliated bronchiolar epithelial cells and APUD cells
- Basal cells-Absent in bronchioles and beyond, they are stem cells responsible for producing new epithelial and goblet cells
- Mast cells-Activation is the main cause of immediate bronchospasm seen in allergen-induced asthma
- Non-ciliated bronchiolar (Clara) cells-Involved in the metabolism of chemical toxins
-Smooth muscle in respiratory tract: Increases as airway gets smaller; it depends on traction from lung itself and having air left in bronchioles to keep the airways open, so its important to have some residual volume (closing volume) left to prevent collapse
-Cartilage
Trachea:
-Adventitia (outermost connective tissue) made up of hyaline cartilage
-Cartilage anteriorly, muscle dorsally/posteriorly (sharing area with esophagus, so if you fill esophagus too much with food its compresses trachea b/c there isn’t hard cartilage there)
-Supported by “U” or “C” shaped cartilages (16-20 in number) joined posteriorly by smooth muscle bands to keep it from collapsing, then incomplete plates (incomplete rings), then eventually complete rings further down
-External pressure of 40 cmH2O is sufficient to compress the trachea at extrathoracic portion
Bronchi:
-“Right and left main bronchus still have a good amount of cartilage b/c they are large and compressible by the pressure in the chest”
-3rd generation its replaced by elastic fibers (in VOPPT says “small amounts of cartilage persist irregularly all the way down to the bronchioles”, but later in slides says there is no cartilage here)
15
Q
List three functions of the respiratory epithelium.
A
- Humidification (heat and moisture exchange)
- Chemical barrier and particle clearance
- Defense against infection
16
Q
Identify the type of epithelium in generations 1-11, 12-18, and 19-23.
A
- Generations 1-11: Columnar ciliated epithelium
- Generations 12-18: Cuboidal/ 15-18 are cuboidal b/t alveoli
- Generations 19-23: Cuboidal between alveoli
17
Q
Identify which bronchus generations have cartilaginous support.
A
- Generations 1-2 have U shaped cartilage
- Generations 2-11 have irregular shaped cartilage
- Generations 12-23 have no cartilage present
18
Q
Identify the cells responsible for bronchospasm in asthmatics
A
Mast cells
19
Q
Identify the mechanism responsible for maintaining potency of generations 5-11.
A
- 5-11 patency relies partially on some cartilage in walls and also positive transmural pressure gradient,
- Needs pressure gradient btw pleural space and airway or airway can collapse
- So pleural space pressure can’t be higher than airway pressure
- “Not enough smooth muscle or air in bronchi to keep them open and not enough cartilage to keep them open”
- These generations constrict and cause air trapping in asthmatics and COPD
20
Q
Identify the generation of bronchioles where the transition from conduction to respiration occurs
A
-Generation 15-18 is where transition from conduction to gas exchange occurs
21
Q
Describe the approximate number of alveoli
A
-About 200-800 million (mean 300 million), depending on height
22
Q
Describe the amount of surface area available for gas exchange.
A
- 50-100 m-squared (about the size of a tennis court) for gas exchange
- Size of alveoli is proportional to lung volume
- Larger in upper part of lung d/t gravitational weight of lung, but vertical size gradient disappears at maximal inflation
- Mean diameter is 0.2mm at FRC (volume that’s left in lungs before with take a breath)
23
Q
Define pores of Kohn and their significance
A
- Small fenestrations in the alveolar septa (adjoining walls of alveoli) that provide collateral ventilation between alveoli
- Allow for passage of gas from an open alveoli to a closed alveoli, so you reduce the amount of V:Q mismatch
- Between 3-13 micrometers in diameter
- Formation is due to: desquamation d/t to disease, normal degeneration d/t aging, or movement of macrophages leaving holes
24
Q
Differentiate between the active side and service side of the alveolar septum.
A
- Active Side: capillary endothelium and alveolar endothelium are close, such that the total distance from gas to blood is 0.3 micrometers, where gas exchange is more efficient
- Service Side: usually more than 1-2 micrometers thick; sizeable interstitial space containing elastin, collagen, nerve endings and macrophages; more affected by edema and fibrous tissue; “can accumulate a lot of fluid on this side before it starts to affect the active side where gas exchange occurs”
25
Differentiate between Type I and Type II alveolar cells.
- Type I epithelial alveolar cells:
- Thin, allow macrophages and albumin to pass between their junctions
- 95% of the alveolar surface
- Made up of squamous pneumocyte cells
- Between 0.1-0.5 micrometers thick
- Major site of gas exchange
- Type II epithelial alveolar cells:
- Stem cells from which Type 1 cells arise
- Involved in pulmonary defense and secrete cytokines (responsible for inflammation)
- Produce and store pulmonary surfactant, primary source
- Only 5% of surface of alveoli
- Composed of granular pneumocyte cells
- Cuboidal in shape with microvilli
- Involved with reabsorption of fluids in the dry, alveolar spaces
26
Discuss the primary function of surfactant.
- Acts as a detergent to decrease surface tension;
- Pulmonary compliance is increased and work of breathing is reduced
- Permits alveolar stability by keeping smaller alveoli from collapsing into larger alveoli (the smaller they are the more they want to collapse on themselves without surfactant)
27
Identify three factors affecting gas diffusion at the alveolar-capillary interface.
- According to Fick, factors affecting diffusion include:
1. Gas concentration gradient
2. Membrane area (OLV, lobectomy)
3. Membrane thickness
28
List four functions of the lungs.
1. Allow oxygen and carbon dioxide exchange
2. Maintain/regulate pH
3. Metabolizes/synthesizes/converts compounds (fentanyl and heparin)
4. Filters unwanted materials from the circulation
5. Acts as a reservoir for blood (amt. of blood in lungs 4-20%)
6. Defense against environment (nose and cilia in bronchi)
29
Describe the difference between the parietal pleura and visceral pleura and their function
- Parietal pleura lines thoracic wall
- Visceral pleura covers the lung surface
- Pleural cavity is space between the two layers
- Pleural fluid fills the space; can get a pleural effusion here
30
Compare the role of the sympathetic and parasympathetic nervous system in regulating bronchial tone.
- Parasympathetic motor fibers (predominate)
- Constrict the bronchi
- Affected by medication, mechanical (minimal effect)
- Sympathetic (weak)
- Dilate the bronchi
- Affected by medication, agents (good impact- albuterol)
- Our drugs seem to work better on sympathetic receptors than parasympathetic
31
Identify the most important muscle in respiration and its innervation.
- Diaphragm (75% of inspiration occurs here)
- Innervated by phrenic nerve (C3-C5)
- Considerable functional reserve (1-7cm)
32
Describe the function of the lymphatic system in the lungs.
- Lymphatic vessels remove fluids and protein molecules that leak out of the pulmonary capillaries
- Transfer fluids back into the circulatory system
- Nodes acts as filters to keep particles and bacteria from entering the blood
- Pathology can lead to edema
33
List three metabolic functions of the lungs.
1. Conversion of angiotensin I to angiotensin II
2. Complete or partial inactivation of vasoactive substances (bradykinin, serotonin, prostaglandins)
3. Metabolism of several vasoactive and bronchoactive compounds such as arachidonic acid metabolites (leukotrienes, prostaglandins, prostacyclin)
4. Major role in clotting mechanism (mast cells contain heparin) and immune system (IgA production)
34
Describe the role of the respiratory system in acid-base balance.
- Increases in carbon dioxide lead to increases in hydrogen ion concentration (H+) as: -CO2 + H2O H2CO3 H+ + HCO3-
- Respiratory system thus participates in acid-base balance by removing CO2 from the body
- CNS has sensors for the CO2 and H+ levels in the arterial blood and CSF which determine minute ventilation
35
The orifice of the right main stem bronchus is how far from the carina?
1 - 2.5 cm
36
Which of the airwayy channel has the smallest dimension?
glottis
37
What nerve provides sensory innervation to the posterior 1/3 of the tongue?
glossopharyngeal
38
What muscles abducts the vocal cords?
posterior crycoartenoids
39
During DL for intubation, you notice the left vocal cord is in an intermediate position what do you suspect?
recurrent laryngeal nerve damage
40
What type of epithelial cells make up the tracheal mucosa?
Pseudostratified Ciliated Columnar
41
What are 3 things that may slow mucociliary transport?
```
cigarette smoke
volatile agent
parasympatholytic drugs(robinol)
```
42
Compared to the conducting zone of the lungs, the respiratory zone has more?
alveoli
43
_____ epithelium are NOT found in the respiratory bronchioles, alveolar ducts and the alveoli?
Ciliated columnar celss
44
What cells are responsible for bronchospasm in asthmatics?
mast cells
45
Potency of the airways in generations 5-11(small bronchi) are dependent upon what?
partially on transmural pressure gradient
46
What is the approximate number of alveoli in the respiratory system?
200-800 million
47
What is the total area available fro gas exchange in the respiratory system?
50-100 meters^2
48
What is the name of the small holes in adjoining alveoli that facilitate ventilation?
Pores of Kohn
49
The respiratory system participates in acid-base balance by?
removing CO2 from the body
50
What is the acid byproduct used by the respiratory system to rid CO2?
Carbonic acid
51
What cells are the primary source of surfactant?
type 2 alveolar cells
52
What are 3 functions of surfactant?
1. decrease surface tension
2. improve pulmonary compliance
3. decrease WOB
53
What are 2 factors which may decrease diffusion at the alveolar-capillary interface?
1. increase gas {} gradient
| 2. increased membrane area
54
What nerve innervates the diaphragm?
phrenic nerve
55
Bronchoconstriction is caused by?
parasympathetic stimulation of the lungs
56
What must happen for airflow to occur during negative pressure ventilation?
transpulmonary pressure gradient must increase
57
What happens to the thoracic cage during inspiration?
it expands
58
During exhalation, what do the intercostal muscles do?
they contract
59
_____ is the change in flow along a tube in relationship to pressure change?
Resistance
60
_____ is the change in pressure in relationship to a change in volume?
Compliance
61
The flow or movement of gas is dependent upon what(3)?
1. elastic resistance of the tissues
2. lung compliance
3. non-elastic resistance of the tissues
62
What decreases surface tension, improves alveolar stability and helps improve lung compliance?
surfactant
63
Which of the following adversely affects lung compliance?
obesity
trendelenberg
pneumoperitoneum
64
In which of the following scenarios would you expect lung compliance to be decreased?
all of them
65
Which has better chance at good lung compliance, lower lobe alveoli in an awake standing patient, or upper lobe alveoli in an awake standing patient?
lower lobe alveoli more compliant that upper lobe alveoli
66
Which generations of the airways has the highest resistance?
upper AWs(generations 3-7 in this example)
67
Which type of flow adversely affects Raw?
turbulent air flow
68
Does a higher Reynolds # or a lower Reynolds # represent low resistance?
the smaller the number the less resistance
69
What are 3 occurrences that may happen when lung volumes are reduced as occurs with decreased FRC during anesthesia?
1. small airways may collapse
2. gas trapping may occur
3. airway resistance may increase
70
_____ is the volume at which small airways dependent on volume to remain open begin to collapse.
closing volume
71
Name at least 3 characteristics of flow-related collapse.
1. forced exhalation in a patient with severe COPD
2. when intrapleural pressure in greater than alveolar pressure
3. when there is a reversal of the normal intracellular airway pressure
72
Patients with increased airway resistance such as in COPD benefit from ?
slow deep breathing
73
Patients with restrictive lung disease such as CF benefit from?
shallow rapid breathing
74
What is the generation #, # of alveoli, diameter in mm, type of cartilage, muscle involvement and the epithelial tissue of the trachea?
Trachea
```
0
1
18
U-shaped
Links open end of cartilage
Columnar ciliated epithelium
```
75
What is the generation #, # of alveoli, diameter in mm, type of cartilage, muscle involvement and the epithelial tissue of the Main Bronchi?
Main bronchi
```
1
2
12
U-shaped
Links open end of cartilage
Columnar ciliated epithelium
```
76
What is the generation #, # of alveoli, diameter in mm, type of cartilage, muscle involvement and the epithelial tissue of the Lobar Bronchi?
Lobar bronchi
```
2-3
4-8
5-8
Irregular Shaped
Helical bands
Columnar ciliated epithelium
```
77
What is the generation #, # of alveoli, diameter in mm, type of cartilage, muscle involvement and the epithelial tissue of the Segmental Bronchi?
Segmental bronchi
```
4
16
4
Irregular Shaped
Helical bands
Columnar ciliated epithelium
```
78
What is the generation #, # of alveoli, diameter in mm, type of cartilage, muscle involvement and the epithelial tissue of the Small Bronchi?
Small bronchi
```
5-11
32-2000
1-3
Irregular Shaped
Helical bands
Columnar ciliated epithelium
```
79
What is the generation #, # of alveoli, diameter in mm, type of cartilage, muscle involvement and the epithelial tissue of the Terminal bronchioles?
Terminal bronchioles
```
12-14
4000-16000
0.7-1
Absent
Strong helical bands
Cuboidal
```
80
What is the generation #, # of alveoli, diameter in mm, type of cartilage, muscle involvement and the epithelial tissue of the Respiratory Bronchioles
Respiratory bronchioles
```
15-18
32000-260000
0.4
Absent
Bands between alveoli
Cuboidal between alveoli
```
81
What is the generation #, # of alveoli, diameter in mm, type of cartilage, muscle involvement and the epithelial tissue of the Alveolar ducts?
Alveolar ducts
```
19-22
520000-4000000
0.3
Absent
Thin bands in septa
Cuboidal between alveoli
```
82
What is the generation #, # of alveoli, diameter in mm, type of cartilage, muscle involvement and the epithelial tissue of the Alveoli?
Alveoli
```
23
8000000
0.2
Absent
Thin bands in septa
Cuboidal between alveoli
```
83
Differentiate between the active side and service side of the alveolar septum.
```
◦ Active side
‣ one side of the alveolar wall, the capillary endothelium and the alveolar epithelium are
extremely close (gas to blood 0.3 micrometers), makes gas exchange very efficient
```
◦ Service side
‣ the capillary wall on this side is 2-3 micrometers thick
‣ there is a sizable interstitial space
‣ more effected by edema and fibrous tissue
84
Discuss the mechanism behind airflow during negative pressure ventilation.
◦ Boyle's Law: volume and pressure are inversely proportional to each other
◦ a pressure gradient must be created between the atmosphere and the alveoli in order for
air to move in or out of the alveoli
When muscles of inspiration are relaxed the transmural ◦ pressure is approx -5 cm H20
◦ As the muscles contract, it increases transmural pressure to -8 and therefore the
interalveolar pressure to a -1 or -2
◦ this creates a pressure gradient to allow lung volume to expand... inspiration
85
Identify the muscles of inspiration and their effect on negative pressure ventilation.
```
Inspiratory muscles
‣ external intercostal muscles
• elevation of ribs and expansion of thoracic diameter
‣ scalenes
‣ sternomastoids
‣ small muscles of face and neck
```
86
Identify the muscles of expiration and their role in active and passive exhalation.
◦ Expiratory muscles
‣ internal intercostal muscles
• contract and pull ribs down and decrease diameter of thoracic cavity
‣ abdominal recti
• pulls rib cage down to assist with forceful expiration
87
Define resistance as it applies to pulmonary mechanics.
Resistance is the change in flow along a tube in relation to a change in pressure
88
Define compliance as it applies to pulmonary mechanics.
Compliance is the change in pressure in relation to a change in volume
89
Describe the components creating the elastic forces in the lungs.
◦ Elastic Fibers in the lungs
‣ elastin and collagen fibers
‣ interwoven within the parenchyma of the lung
• stretched when lung inflated, relaxed when lung deflated
• always exerting a force toward deflating the lung
◦ Surfactant
‣ decreases surface tension, promotes stability, and increases compliance and decreases
work of breathing
◦ Lung Compliance
‣ as transpulmonary pressure increases, lung volume increases
‣ the change in volume in relation to the change in pressure is compliance
‣ factors effecting compliance
• pulmonary blood volume
• age
• bronchial smooth muscle tone
• disease
• lung volume (the fibers can only stretch so far, and the lung volume can only
increase so much)
90
List three functions of surfactant
◦ Detergent to decrease the surface tension within the alveoli, decreasing the tendency of the
alveoli to collapse
◦ promotes alveolar stability to by keeping smaller alveoli from collapsing
◦ pulmonary compliance is increased and work of breathing is decreased
91
List two factors maintaining alveolar stability.
◦ surfactant helps to stabilize alveoli
◦ alveoli are mechanically interdependent polygons with flat shared walls
‣ they are held open by the chest wall pulling on the lung
92
Describe the pressure-volume curve for the human lung.
◦ the pressure volume curve is not linear
◦ the volume of the lung changes very easily with very little pressure, but changes very little
when the lung volume is high
93
List five factors affecting lung compliance.
```
◦ pulmonary blood volume
◦ age
◦ lung volume
◦ disease
◦ bronchial smooth muscle tone
```
94
Describe the effect of the thorax on lung compliance and provide examples.
◦ Total compliance relies on both lung compliance and chest wall compliance
◦ Decreased chest wall compliance
‣ obesity
‣ pathological skin conditions - burns, scar tissue
‣ kyphosis
‣ pneumoperitoneum
‣ posture
95
Compare compliance of upper regions of the lungs to lower regions of the lung.
◦ Upper regions of the lung
‣ receive less ventilation than lower lung
‣ are less compliant as the volume changes little with pressure
◦ Lower regions of the lung
‣ lower lung alveoli, which are dependent, receive more ventilation than the upper region
‣ the lower lung is more compliant as the volume changes more than pressure
96
Describe the effect of position changes such as trendelenberg and semi-recumbent positions
on compliance and FRC.
◦ Functional Residual Capacity (FRC) is the point at which
the outward recoil of the chest wall is equal to the inward
recoil of the lung tissue
◦ The capacity of the lung at end of passive, not forced,
exhalation
◦ Effect of position on FRC (all values are +/- 1SD)
‣ Standing - 3.25 L
‣ Sitting and Recline at 60* - 2.75 L
‣ Recline at 30* - 2.5 L
‣ Supine - 2.0 L
‣ Trendelenberg 30* - 1.80 L
97
Describe the effect of positive pressure ventilation a • nd anesthesia on lung compliance
◦ Lung compliance decreases with general anesthesia
◦ Paralysis doesn't decrease compliance, but may raise the position of the diaphragm within
the abdominal cavity
◦ surgical position, and retractors can decrease compliance
◦ positive pressure ventilation
‣ instead of the negative pressure pulling down and increasing the alveolar volume
‣ positive pressure forces air down into lungs, compressing alveoli and therefore
decreasing alveolar volume available for ventilation/diffusion
98
List three factors affecting airway resistance.
◦ radius of airway
◦ turbulence (density) of the air
◦ length of the airway
99
Identify the airways that have the most resistance and why.
◦ medium airway, generation 3-7 have the most resistance
◦ larger airways have larger radius
◦ smaller airway have large cross-sections
100
Define Reynold's number and it's relationship to resistance during anesthesia
◦ Reynold's number is a measure of density
◦ gasses with a lower reynolds number have less resistance during turbulent flow and
therefore will resume laminar flow more easily
◦ Gas with Reynold's number > 2000 are associated with turbulent flow, < 1000 is associated
with laminar flow
101
Identify the roles of PSNS and SNS in regards to determination of airway resistance.
◦ PSNS
‣ both afferent and efferent arise from the vagus nerve
‣ Afferent
• arise from bronchial epithelium and responds to stimulation from cytokines from
mast cells
‣ Efferent
• releases acetylcholine at muscarinic receptors resulting in bronchostriction
◦ SNS
‣ Efferent
• sympathetic efferent may oppose acetylcholine slightly but it is very weak
‣ Bronchiole smooth muscle is sensitive to adrenaline, beta-2 receptors
• balances the cholinergic effect of bronchoconstriction
102
Describe the role of VIP in airway resistance.
◦ vasoactive intestinal polypeptide is a neurotransmitter that produces nitric oxide
◦ nitric oxide activates guanylate cyclase to produce cyclic GMP and create muscle
relaxation
◦ sensory fibers in the neural pathways are sensitive to smoke and other irritants
‣ release substance P and neurokinin A --> potent bronchoconstriction
103
Describe how mechanical stimuli may elicit bronchospasm
◦ mechanical stimulation of the respiratory epithelium activates the parasympathetic reflex
◦ afferent response to mast cells
◦ efferent release of acetylcholine to muscarinic receptors --> bronchoconstriction/
bronchospasm
104
Identify the MOA of alupent, albuterol, • atrovent, and cromolyn.
```
◦ Alupent
‣ sympathetic/ beta-2
◦ Albuterol
‣ sympathetic/ beta-1 and beta-2
◦ Atrovent
‣ parasympathetic/ Ch
◦ Cromolyn
‣ Antihistamine
```
105
Describe the effects of volatile agents on airway resistance
◦ volatile agents cause bronchodilation which offsets the decrease in FRC's effect on airway
resistance
◦ may cause posterior displacement of the tongue, extra secretions, laryngospasm
◦ Isoflurane and Desflurane are slight airway irritants
◦ Inhibits acetylcholine/vagal mediated bronchoconstriction in dose-dependent manner
‣ sevo and des do this the most
‣ sevo > des (because sevo is less pungent than des)
◦ Dose-dependent decreases in airway resistance
‣ decrease in vagal activity
‣ Sevo>Halo>Iso
106
Describe the relationship between lung volume and airway resistance.
◦ when lung volume is reduced, airway resistance increases
◦ at very low lung volumes, airways collapse
◦ gas-trapping occurs d/t expiratory airway collapse from pleural pressures
107
Define "closing capacity".
◦ smaller airways lack cartilaginous support and are dependent on lung volume
◦ the volume at which these small airways close is called closing capacity
◦ closing capacity is less than FRC, but the gap gets smaller and smaller as we age, passing
the FRC at age 66
108
Describe the benefit of PEEP in optimizing FRC and closing capacity.
◦ When a patient is on a ventilator with IPPB, the addition of PEEP makes the FRC greater than the closing capacity
109
List four factors determining FRC in abdominal surgery. Progressive decrease in FRC with each step.
◦ supine position
◦ induction of anesthesia
◦ paralysis
◦ surgical position and displacement of the diaphragm
110
Define "flow related airway collapse" as it relates to resistance in asthmatics.
◦ during forced exhalation, the there can be a reversal of the normal intrapleural airway
pressure from a negative to a positive
◦ in healthy lungs this does not provide a problem
◦ in asthamtic/emphysema patients, the intrapleural pressure overcomes the alveolar
pressure causing alveolar collapse, and therefore an increase in airway resistance
111
Describe the effect of anesthesia on tissue resistance.
◦ in a spontaneously breathing patient, tissue resistance is nominal
in an anesthetized and paralyzed patient, tissue r ◦ esistance (from chest wall and lung
tissue) may account for approx 50% of the respiratory system resistance
112
Describe the effect of increasing respiratory rates in the pt with obstructive lung disease.
In patients with COPD a respiratory rate greater than 15 breaths/min, compliance of the
lungs decreases d/t resistance in the small airways
113
Identify the effect of COPD on work of breathing.
◦ Pt's with COPD can have increased work of breathing up to 6 times.
◦ Can benefit from slow, deep respirations
