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Respiratory Therapy 100 > Final > Flashcards

Final Flashcards

1
Q

In what portion ofthe lungs does alveolar deadspace normally occur?

A

Apices

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2
Q

Airway Resistance Formula

A

Change in pressure/flow

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3
Q

Normal Airway Resistance

A

0.5-2.5 cmH2O/L/sec

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4
Q

Under resting metabolic conditions, how much carbon dioxide does a normal adult produce per minute?

A

200ml/min

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5
Q

What is the term for the opposition to ventilation caused by the movement of gas through the conducting airways?

A

Airway Resistance

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6
Q

Compliance Formula

A
  • Volume/Pressure

- 1/elastance

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7
Q

Elastance Formula

A
  • Pressure/Volume

- 1/compliance

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8
Q

Total Compliance Formula

A

Lung compliance x Chest wall compliance/ Lung compliance + chest wall compliance

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9
Q

Heart Pathway

A

Right Atrium->Right Ventricle->Pulmonary Artery->Pulmonary Capillaries->Pulmonary Vein->Left Atrium->Left Ventricle->Aorta->Systemic Capillaries->Vena Cava

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10
Q

What kind of blood does the Pulmonary Arteries and Veins carry?

A

Pulmonary Artery: deoxygenated blood. Only artery in body that carries deoxygenated blood.
Pulmonary Vein: oxygenated blood. Only vein in the body that carries oxygenated blood.

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11
Q

Whats the PaO2 in the pulmonary artery?

A

40 mmHg

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12
Q

Whats the PaCO2 in the pulmonary artery?

A

46 mmHg

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13
Q

Whats the PaO2 in the pulmonary vein?

A

100 mmHg

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14
Q

Whats the PaCO2 in the pulmonary vein?

A

40 mmHg

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15
Q

Time Constant Formula

A

Resistance x Compliance

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16
Q

Pseudoglandular Stage

A
  • 6th, 7th-16th week
  • lung resembles hollow tube like (glandular) structure surrounded by mesenchymal cells
  • lined with cuboidal epithelial cells
  • first type II pneumocytes appear
  • terminal bronchioles begin to differentiate to form respiratory bronchioles and alveolar ducts
  • cartilage begins to form around larger airways and smooth muscles forms around airways and major blood vessels
  • production of fetal lung liquid
  • NOT capable of extrauterine survival
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17
Q

Canalicular Stage

A
  • canaliculi (canals) begin to branch out from terminal bronchioles
  • all alveoli developed from a single terminal bronchiole form an acinus
  • capillaries surround the acini in dense layer making gas exchange possible
  • cuboidal Type II pneumocytes flatten into Type I pneumocytes
  • alveolar septa start becoming thinner
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18
Q

Saccular Stage

A
  • 26th week-birth
  • peripheral air spaces have saclike appearance
  • sacs distal to terminal bronchioles begin to lengthen
  • 1st generation of sacs that will become alveoli are formed
  • interstitial material compressed, capillary and alveoli move closer
  • Type II cells produce and store pulmonary surfactant
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19
Q

Alveolar Stage

A
  • 32nd week-8th or 10th year of life
  • formation of the hexagonal shaped alveoli
  • terminal saccule become enclosed in tissue sheath
  • epithelial cells form crests that develop into alveolar septa
  • septa separates individual alveoli and increase surface area for gas exchange
  • number of alveoli provide 3-4m^2 of gas exchange surface area
  • adult lung has a gas exchange surface area of 50-100m^2
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20
Q

Fick’s Law of diffusion

A

rate of diffusion of a gas through a tissue sheet is directly proportional to the surface area

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21
Q

Dead Space

A

1 cc or 1 ml per lb of body weight
-gas that doesn’t participate in gas exchange
physiological dead space= anatomical dead space + alveolar dead space

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22
Q

Inspiratory Expiratory Ratio

A 
Total Cycle Time= 60/Respiratory Rate
Inspiratory Time + Expiratory Time = TCT
TI=TCTx I/ I+E
End Expiratory Pause = 25% of TE
TE/TI= I:E
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23
Q

Dead Space Tidal Volume Ratio

A

VD/VT= (PaCO2-PECO2)/PaCO2

VD=VT(PaCO2-PECO2)/PaCO2

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24
Q

Alveolar Minute Ventilation

A

V(with dot on top)A= (VT-VD) x RR

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25
Q

Minute Ventilation

A

V(with dot)= VT x RR

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26
Q

Hemoglobin Arterial Oxygen Saturation Equation

A

SaO2= HbO2/Total Hb x 100

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27
Q

Oxygen Carrying Capacity of blood

A

grams/dl of Hb x 1.34ml/g

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28
Q

Total Oxygen Content of the blood equation

A

CaO2=(0.003 x PaO2)+(Hb total x 1.34 x SaO2)

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29
Q

Hemoglobin Saturation

A 
PaO2 (torr) | Saturation
27 torr - 50%
40 torr - 70%
50 torr - 80%
60 torr - 90%
100 > more torr - 97%-100%
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30
Q

Alveolar Air Equation

A 
PAO2= FiO2(PB-PH2O)-(PACO2/0.8)
PH2O= 47mmHg
PaCO2= 40mmHg
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31
Q

Oxyhemoglobin Dissociation Curve to the RIGHT

A
  • occurs in the SYSTEMIC capillaries
  • pH decreases: blood picks up CO2 causes pH decreases, lowers affinity for Oxygen
  • Temperature increases, affinity for oxygen decreases when exercising
  • occurs during hypoventilation
  • increased 2,3 DPG, promotes O2 unloading and reduces affinity for O2
  • RBCs produces more 2,3DPG when metabolically active, more when temperature is high
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32
Q

Oxygen Dissociation Curve to the LEFT

A
  • occurs in the PULMONARY capillaries
  • pH increases, when venous blood returning to the lungs and CO2 diffuses out causes pH increase
  • this increases affinity of Hb for O2 and enhances its uptake of Oxygen from alveoli
  • body temperature goes down, Oxygen affinity goes up
  • 2,3 DPG production decreases, O2 affinity goes up
  • occurs during hyperventilation
  • RBCs producing less 2,3DPG
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33
Q

Oxygen Delivery Formula

A

D(with dot)O2= CaO2 x Q

Oxygen minute delivery)=(oxygen content) x (Cardiac Output

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34
Q

Respiratory Exchange Ratio

A

R=V(with dot)CO2/V(with dot)O2

R=(minute CO2 production)/(minute O2 consumption)

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35
Q

Normal Respiratory Exchange Ratio

A

R= 200/250= 0.8

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36
Q

Under resting metabolic conditions, how much Oxygen does the body consume per minute?

A

250ml/min

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37
Q

Hypoxemia

A

-when the PaO2 is lower than the predicted normal value based on age
Causes:
1. Inadequate amount of )2 is reaching the alveoli
-hypoventilation, tachypnea (rapid shallowing breathing)
2. Inadequate amount of O2 crossing A/C membrane
-low PB causing a low PO2, low FiO2

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38
Q

Haldane’s Effect

A
  • describes how high levels of O2 in the lungs increase Hb’s affinity for O2 and decreases its affinity for CO2
  • high O2 levels speed up loading of the O2 onto Hb at the lungs producing saturated Hb
  • HbO2 has a low affinity for CO2 so unloading and loading of O2 are sped up at the lungs
  • also works to a lesser degree in tissues
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39
Q

Bohr’s Effect

A
  • describes how high levels of CO2 and H+ in the tissue decrease Hb’s affinity for O2 and increases affinity for CO2
  • high CO2 and H+ speed up unloading of O2 to cells and producing deoxygenated Hb
  • Deoxygenated Hb has high affinity for CO2 so loading of CO2 and unloading of O2 are sped up at the tissues
  • also works to a lesser degree at the lungs
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40
Q

Hypoventilation

A
  • CO2 levels increase, breathing too slow
  • can cause hypoxemia and hypoxia
  • can be caused by medication overdose causing the central chemoreceptors to become depressed
  • shifts curve to the right
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41
Q

Hyperventilation

A
  • O2 levels rise, CO2 levels fall
  • breathing too fast causes exhaling of CO2 faster than cells are producing it
  • shifts curve to the left
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42
Q

How does the changes in blood pH impact Hb affinity for O2? (Bohr’s Effect)

A
  • low pH shifts curve to the right, saturation decrease and Hb affinity decreases
  • high pH shifts curve to the left, Hb saturated and Hb affinity increases
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43
Q

Percent Relative Humidity Formula

A

%RH=content/capacity x 100

Normal Body Temperature alveolar capacity at body temp= 44 mg/L

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44
Q

Formula for Density of Air

A

Density=m/v
Density of Air= (FN2 x gmwN2) + (FO2 x gmwO2)/ 22.4 L
STP=22.4

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45
Q

F->C->K

A
  • C= 5/9(F-32)
  • K=C+273
  • F=(9/5 x C) +32
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46
Q

Hydrostatic Pressure Formula

A
  • PL= Height x Density

- density = 1 g/cm3

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47
Q

Hamburger Effect

A
  • when chloride ions shift from plasma into RBC
  • Chloride shift
  • to maintain a concentration equilibrium across cell membrane
  • reverse chloride shift occurs in pulmonary capillaries
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48
Q

Boyles Law

A

V1 x P1= V2 x P2

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49
Q

Charles Law

A

V1/T1 = V2/T2

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50
Q

Gay Lussacs Law

A

P1/T1 = P1/T1

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51
Q

Henry’s Law

A

The amount of dissolved gas is proportional to its partial pressure in the gas phase

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52
Q

Poiseuille’s Law

A

Fluid flowing through a tube looses pressure as energy is converted to heat while overcoming frictional resistance

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53
Q

Obstructive diseases

A
  • high compliance and low elastance
  • pressure becomes positive to get air out
  • emphysema (COPD)
  • takes longer to inhale and exhale
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54
Q

Restrictive Diseases

A
  • low compliance, high elastane
  • asthma, pneumonia
  • shorter time inhaling and exhaling
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55
Q

What causes the baby to take it’s first breath?

A
  • central chemoreceptor cells in the medulla signal the respiratory muscles to work in response to receptor stimulation by
  • acidosis
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56
Q

Pump Handle movement of ribs

A
  • muscle contraction rotates the rib heads around the costovertebral joints, pulls up the distal ends of the ribs, especially ribs 2-7
  • lifting the sternum and displacing it anteriorly
  • increases the anteroposterior dimension of thorax
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57
Q

Bucket Handle movement of ribs

A
  • same muscle contraction rotates the long axis of the ribs and reduces their downward slant
  • increases the lateral (transverse) dimension of the thorax
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58
Q

What muscles are the primary respiratory muscles?

A
  • Diaphragm and external intercostals

- both used during quiet breathing and exercising

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59
Q

Maximal contraction for the diaphragm is?

A
  • 10 cm

- normal contraction: 1.5 cm (1-2cm)

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60
Q

Internal intercostal muscles

A
  • responsible for forced exhalation

- depress the ribs and decrease space in the chest cavity

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61
Q

External intercostal muscles

A
  • responsible for forced and quiet inhalation

- raise the ribs and expand the chest cavity

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62
Q

What muscles are used when in the Tripod position?

A

Pectoralis muscles
-allows the patient to fix the head and the pectoral (shoulder) girdle allowing the pectoralis muscles to general some anterior thoracic lift

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63
Q

Trapezius Muscle Use

A

-produces visible clavicular lift where the clavicle rise > 5 cm with each inspiration

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64
Q

Retractions

A
  • when airway resistance is high the patient must produce a large trans-chest wall pressure gradient
  • causes atmospheric pressure to press the skin of the chest tightly against the ribs during spontaneous inspiration
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65
Q

Costophrenic Angles

A

-formed by the costophrenic recesses, the points where the hemidiaphragms meet the chest wall

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66
Q

Differences between the parietal and visceral layers

A
  • the visceral layer is about 100 u thick, parietal layer is thinner at about 20 u
  • only the parietal layer has stomata (openings) in the mesothelial layer
  • only the parietal layer has nerve fibers that sense pain
67
Q

Purpose of pleural fluid

A
  • acts as a lubricant between the visceral and parietal layers to aid in lung movement during breathing
  • acts to cohesively bind the two pleural layers together so that chest wall forces can be transmitted to the lungs
68
Q

Transudative Pleural Effusion Fluid

A
  • usually results from conditions that normally produce and remove pleural fluid to get out of balance
  • fluid is clear, similar to blood plasma
69
Q

Exudative Pleural Effusion Fluid

A
  • often caused by disease of the pleura itself

- fluid is usually cloudy and contains large amounts of protein

70
Q

Hilus

A

a depression or pit at the part of an organ where vessels and nerves enter

71
Q

Why are the lungs divided into lobes and lobules?

A
  • each lung lobe has minimal connection with the other lobes
  • the segments are functionally independent
  • this increases efficiency and limits the spread of pathology throughout the lung
72
Q

systemic circulatory system

A

high pressure, high resistance, long distance system that carries blood to the entire body

73
Q

pulmonary circulatory system

A

low pressure, low resistance, short distance system that carries blood to the pulmonary capillary beds where gas exchange occur

74
Q

Lymph fluid

A
  • fluid flows out of arteriole end of the capillary
  • about 90% is reabsorbed at the venous end
  • 10% becomes part of interstitial fluid that surrounds the tissue cells
  • Lymphatic capillaries pick up excess interstitial fluid and proteins and return them to the venous blood
75
Q

Pulmonary Edema

A

occurs when the volume of liquid moving into the pulmonary interstitial from the capillaries is greater than the amount of fluid removed by reabsorption and lymphatic drainage
-will cause pulmonary restriction (reduced alveolar expansion)

76
Q

Where are the peripheral and central chemoreceptors located in the brain?

A
  • wall of aorta and carotid arteries

- medulla oblongata

77
Q

What controls the rate and depth of breathing in normal people?

A

The PaCO2 of the blood reaching the brain.

  • increased H+ concentration in the ECF stimulates ventilation
  • decreased H+ concentration in the ECF inhibits (reduces) ventilation
78
Q

Ventral and Dorsal Respiratory Groups

A

VRG: contains both expiratory and Inspiratory neurons, but mostly associated with expiration
DRG: mostly contains inspiratory neurons

79
Q

Scalene Muscles

A
  • arise from the lower five or six cervical vertebrae and insert on the clavicle and first two ribs
  • lift the upper chest when active
  • slightly active during rating inhalation and become more active with forceful inspiration and when ventilatory demands increase
  • when alveolar pressure decrease to -10 cmH2O
80
Q

Sternocleidomastoid Muscles

A
  • originate from the manubrium and clavicle and insert on the mastoid process of the temporal bone
  • can function to lift the upper chest
  • become active during forceful inspiration and become visible as thick bands on either side of the neck
  • increases the anteroposterior diameter of the chest
81
Q

What is the narrowest point in the airway of the adult an the older child?

A

glottis

82
Q

What is the point of division between the upper and lower airways?

A

glottis

83
Q

What is the narrowest point in the neonatal and younger child’s upper airway?

A

Cricoid

84
Q

Cricoid Cartilage

A
  • lies below thyroid cartilage
  • only complete tracheal ring
  • thyroid and cricoid are connected by the cricothyroid membrane
85
Q

Larynx

A
  1. It’s a gas conducting passage between the upper and lower airways
  2. protects the lower airway from aspiration of foreign materials
  3. participates in the cough mechanism
  4. participates in speech
86
Q

What is the epiglottis attached to?

A
  • to the thyroid cartilage and the base of the tongue

- it covers the glottis during swallowing

87
Q

Where do the vocal cords lie?

A

in the center of the larynx

88
Q

Tracheal Reflex

A
  • vagovagal reflex

- causes a violent cough when a foreign object or irritation stimulates the trachea

89
Q

Carinal Reflex

A
  • vagovagal reflex

- causes a powerful cough when the tracheal carina is stimulated

90
Q

Where does the two main stem bronchi divide?

A

at the angle of Louis (sternal angle)

91
Q

Which bronchus is more directed into the lungs?

A

right bronchus because it is wider, shorter, and more vertical than the left main bronchus

92
Q

Cartilaginous Airways

A
  • provide structural support to the airways where bulk flow is primary mechanism of gas movement
  • include: trachea, mainstem bronchi, lobar bronchi, segmental bronchi, and sub-segmental bronchi
93
Q

Non-Cartilaginous Airways

A
  • contain elastic fibers
  • diffusional flow is primary mechanism for gas movement in these airways
  • are the smallest units of conducting zone
  • includes: bronchioles and terminal bronchioles (terminal and respiratory bronchioles, and alveolar ducts and sacs)
94
Q

Where do cilia and goblet cells disappear?

A

at the respiratory bronchioles

95
Q

What are contained in the lamina propria?

A

contains submucosal ducted mucous glands, fibrous tissue, blood and lymph vessels, branches of the vagus nerve and two bands of smooth muscle
-the peribronchial sheath covers the outer lamina propria

96
Q

How much mucus does the goblet cells and mucus glands produce in a day?

A

100 ml/day

97
Q

What makes up the anatomical dead space?

A

The airways from the nares to the terminal bronchioles

98
Q

How much is dead space?

A

1 ml/lb of ideal body weight

99
Q

Type I pneumocytes

A
  • flatter squamous epithelial cells

- become primary gas exchange cells in the lungs

100
Q

Type II pneumocytes

A
  • cuboidal secretory cells
  • have microvilli and produce pulmonary surfactant
  • can proliferate and differentiate into type I cells
101
Q

Segmental Bronchi

A
  • cartilaginous airways
    1. have connective tissue coverings
    2. are larger than 1 mm in diameter
102
Q

Bronchioles

A
  • non-cartilaginous airways
    1. lack connective tissue coverings
    2. are less than 1 mm in diamenter
103
Q

Lobes

A
  • Right lung divided into 3 sections

- Left lungs divided into 2 sections

104
Q

Clara cells

A
  • non-mucous and non-ciliated secretory cells located in the bronchioles
  • help protect the bronchiolar epithelium by
    1. secreting a variety of products including Clara cell secretory protein an a chemical component of pulmonary surfactant
    2. detoxifying harmful substances inhaled into the lungs
  • can multiply and differentiate into ciliated cells to help regenerate damaged epithelium
105
Q

Pores of Kohn

A
  • small openings in the alveolar septa
  • NOT sites of gas exchange
  • about 10-14 micros in diameter
106
Q

Canals of Lambert

A

-connect alveoli to secondary bronchioles

107
Q

Purpose of the pores and canals

A
  • may be an adaptation to permit collateral gas flow to alveoli that have been blocked by a proximal obstruction
  • probably provide very little collateral ventilation in normal lungs
  • contribute to the spread of bacterial infections and cancer cells
108
Q

Pulmonary Surfactant functions

A
  • decreases surface tension forces at the alveolar air/water interface
  • helps prevent alveolar collapse at the end of expiration, especially smaller ones
  • keeps distal airways and lung parenchyma clinically sterile
109
Q

Causes of Edema

A
  1. increased hydrostatic pressure inside capillaries
  2. reduced oncotic pressure
  3. increased capillary wall permeability (makes capillaries leaky)
  4. reduced lymphatic draining
110
Q

Barorecptors

A
  • groups of cells specialized to respond to stretching of blood vessel walls caused by increases in arterial blood volume and pressure inside the vessel
  • aortic body baroreceptors send messages to the cardiovascular control centers to regulate blood pressure
111
Q

Dew Point

A

the gas temperature at which condensation occurs

112
Q

Cohesion

A
  • occurs molecules of the same material stick together

- surface tension

113
Q

Adhesion

A
  • occurs when molecules of different materials stick together
  • capillary action
114
Q

Conduction

A
  • the movement of heat energy through a stationary solid

- heat transferred to the metal handle of the pot

115
Q

Convection

A
  • fluid motion
  • movement of gases or liquids containing heat energy from warmer to cooler areas
  • hotter molecules of water near the bottom of the pot transfer heat to colder molecules near the top
116
Q

Critical pressure

A

the pressure needed to liquefy the vapor phase at temps below critical temp

117
Q

Pascal’s Principle

A

liquids and gases exert pressure equally in all directions

118
Q

Pressure formula

A

pressure=force/area

119
Q

Pressure Conversions

A

760mmHg=760torr, 1 atm, 101,325 Pa, 101.3 kPa, 14.7 psi, 1,034 cmH2O

120
Q

Dalton’s Law of Partial Pressure

A

-in a mixture of gases, each gas will exert a part of the total pressure
-in a normal person at sea level:
water vapor pressure = 47 mmHg
Nitrogen= 573mmHg
CO2= 40 mmHg
O2=100mmHg

121
Q

Reynold’s Number

A

predicts whether fluid flow will be laminar or turbulent

-if # greater than 2000 its turbulent

122
Q

Flow formula

A

flow=volume/time

123
Q

Fluid Velocity

A
  • law of continuity requires that the forward velocity of the water must increase to maintain a constant flow rate throughout the tube
  • velocity of a fluid flowing through tube at a constant flow rate varies inversely with the cross-sectional area of tube
124
Q

Bulk vs. Diffusional Flow

A
  • large airways have bulk flow, more turbulent in larger airways
  • small airways have diffusional flow, more laminar flow in smaller airways
125
Q

Resistance to flow

A
  • determined by tube radius, tube length, and fluid viscosity
  • R=(P1-P2)/flow
126
Q

Surface Tension

A
  • cohesive forces pull the molecules at the liquid gas interface together strongly
  • acts to increase elastic recoil
  • helps lung to empty during exhalation
  • too much will lead to low compliance and could cause lungs to collapse
  • too little results in air trapping and lung hyperinflation
  • during inspiration they have no effect on alveolar expansion or gas exchange
127
Q

Pulmonary Surfactant

A

-reduce surface tension

128
Q

Bernoulli’s Principle

A

-as velocity increases, pressure decreases because of less collisions

129
Q

Graham’s Law of Diffusion

A
  • diffusion is inversely proportional to the square root of the molecular weight of the gas (lighter molecules diffuse faster than heavy ones)
  • CO2 diffuses across A/C membrane about 19 times faster than O2
  • higher the concentration of O2 in the alveoli the more O2 diffuses across the A/C membrane
130
Q

Solubility Coefficients

A

Oxygen: 0.023 ml O2 / ml plasma
CO2: 0.510 ml CO2 / ml plasma
-only 0.003 ml can dissolve in each dl of plasma for every 1 mmHg of PO2

131
Q

Spirometry Pulmonary Functions

A

Box

  1. TLC
  2. VC+RV
  3. IC+FRC
  4. IRV+VT+ERV+RV
    - IRV+VT+ERV=VC
    - IRV+VT=IC
    - ERV+RV=FRC
132
Q

Transrespiratory Pressure Gradient

A
  • across the entire respiratory system
  • difference between atmosphere and alveoli
  • book says: (Pao-Pbs)
  • airway opening pressure and alveolar pressure are same during breathing
  • responsible for moving air into and out of alveoli during breathing
133
Q

Transpulmonary Pressure Gradient

A
  • across the lungs
  • responsible for moving air into and out of lungs
  • (Pao-Ppl)
134
Q

Transthoracic Pressure Gradient

A
  • pressure across the chest wall

- represents the total energy needed to expand or contract both the lungs and the chest wall

135
Q

Regional factors affecting the distribution of gas in the normal lung result in which of the following?

A

More ventilation goes to the bases and lung periphery

136
Q

A patient has a PCO2 of 56 mm Hg. Based on this information, what can you conclude?

A

The patient is hypoventilating

137
Q

Which of the following pressure gradients is responsible for maintaining alveolar inflation?

A

Transpulmonary Pressure Gradient

138
Q

Which of the following pressure gradients is responsible for the actual flow of gas into and out of the lungs during breathing?

A

Transrespiratory Pressure Gradient

139
Q

The presence of surfactant in the alveoli tends to do which of the following?

A

Increases compliance

140
Q

How can the body effectively compensate for physiologic deadspace?

A

increasing tidal volume

141
Q

What is the single best indicator of the adequacy or effectiveness of alveolar ventilation?

A

PaCO2

142
Q

An area with perfusion but no ventilation (and thus a V/Q of zero) is termed?

A

Shunt

143
Q

An area with ventilation but no perfusion (and thus a V/Q undefined though approaching infinity) is termed

A

Dead space

144
Q

Hypercapnia

A

excessive amount of CO2 in blood

145
Q

What is the normal P(A - a)O2 range while breathing room air?

A

10 mm Hg to 25 mm Hg

146
Q

Which pressure remains subambient throughout ventilation?

A

Pleural pressure

147
Q

What are the two forces opposing lung inflation?

A

Elastic resistance and frictional resistance

148
Q

Hysteresis

A

the difference between expiration and inspiration pressure curves

149
Q

What does hysteresis in the lung show?

A

Shows that another force besides elastic recoil must be at work during deflation of the air filled lung which is surface tension

150
Q

Work Formula

A

WOB=change in pressure x change in flow

-force x distance moved

151
Q

a/A Ratio

A
  • evaluates the efficiency of O2 transfer from alveoli into blood
  • normal a/A ratio is > or equal to 90%
  • normally 90% of alveolar O2 diffuses across the A/C membrane
  • a high P(A-a)O2 and a low a/A ratio are evidence of a diffusion defect
152
Q

P(A-a)O2

A
  • difference between alveolar and arterial PO2
  • should be a very low number
  • less than 5-10 torr on room air and less than or equal to 65 torr on 100% FiO2 or less than the patient’s age
153
Q

How is oxygen carried in the blood?

A

Dissolved in plasma and bound to hemoglobin

154
Q

Dissolved O2 in blood

A

PaO2 x 0.003= 100 torr x 0.003 = 0.3 vol%

155
Q

Factors that lower CaO2 without affecting PaO2

A

anemia(reduction in Hb), CO poisoning, metHb, and various conditions that cause an excessive and permanent shift in the HbO2 curve

156
Q

Normal C(a-v)O2

A

about 5 vol%

157
Q

Modes of CO2 transport

A
  1. dissolved in plasma 5-10%
  2. bound as carbamates: about 12-22%
  3. as bicarbonate ions both in RBC and in plasma: about 80-90%
158
Q

Anatomical Shunts

A

occur when blood passes from the right side of the circulation to the left side without entering the pulmonary capillaries
-congenital heart defects, and tumors of the pulmonary vasculature

159
Q

Capillary Shunts

A

occur when the blood from the right circulation passes through the pulmonary capillaries but no gas exchange occurs
-most common cause is atelectasis

160
Q

Shunt-like Effect

A

occurs when pulmonary perfusion exceeds alveolar ventilation

  • most common causes are hypoventilation, uneven distribution of ventilation, and A/C diffusion defects
  • usually responsive to oxygen therapy
161
Q

Venous Admixture

A

final result of all types of shunting

-deoxygenated blood mix with oxygenated blood and lower the overall O2 content of arterial blood

162
Q

Cardiac Output

A

Stroke Volume x Heart Rate

163
Q

V/Q ratio

A
  • if ventilation decreases, V/Q ratio will become lower
  • if perfusion decreases, V/Q ratio will become higher
  • normally alveolar ventilation/cardiac output= 4.2 L/min / 4.9 L/min = 0.8
164
Q

O2 attached to Hb

A

Not part of the PaO2

Respiratory Therapy 100 (1 decks)

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