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the process of moving air in out the of the lungs
define tidal volume
what is a normal tidal volume
tidal volume is the amount of air that is breathed in and out of the lungs
- normal is 500ml
- but it can change during excercise or sleep to meet metabolic needs
what is the equation related to pressure and
what does each component stand for
pressure= (volume/resistance)+(resistance x flow)
- volume: volume change
- resistance: airflow and tissue resistance
- flow= volume change per unit of time
Ptr(transrespiratory pressure) consists of
P at the airway opening - pressured measured at the body surface
PAO - PBS
pressured measured at the opening of the respiratory system airway
mouth & nose, tracheostomy opening, distal end of endotracheal tube
PTAW (transairway pressure) consist of
difference between airway opening and alveoli
what does PTA (transalveolar pressure) consist of
difference between alveolar pressure and pleural pressure
during spontaneous breathing what happens to Pa
Pa is subambient and lower the Pao therefore air flows from high (pao) to low (pa)
the opposite happens during expiration
what is the primary function of the lungs??
during each cycle of normal resting ventilation, a volume of ga is moved into and out the respiratory tract. this cyclical volume is called the
Tidal Volume (VT)
which of thr following pressures vary throughout the normal breathing cycle?
1. alveolar Pressure (P alv)...intrapulmunary P
2. Body Surface Pressure (P bs)
3. Mouth Pressure (P ao)
4. pleural pressure (P pl)
- Alveolar Pressure
- Pleural Pressure
Which of the following pressures normally remains negative (relative to atmospheric pressure) during quiet breathing?
a. P alv
b. P pl
c. P ao
d. P bs
which of the following pressure gradients is responsible for the actual flow of gas into and out of the lungs during breathing?
a. transcanadian P gradient
b. transpulmonary P gradient
c. transrepiratory P gradient
d. transthoracic P gradient
the trasrepiratory gradient causes gas to flow into and out of the alveoli during breathing.
which of the following pressure gradient is responsible for maintaining alveolar inflation?
a. Transpulmonary P gradient (Palv -Ppl)
b. transthoracic P gradient (Ppl - Pbs)
c. Transcanadian P gradient ( Pca- Pks
d. Transrespiratory P gradient (Palv- Pao)
Transpulmonary or Pl is the pressure difference that maintains alveolar inflation.
Which of the following statements about alveolar pressure (Palv) during normal quiet breathing?
a. its positive during inspiration and negative during expiration.
b. it is the same as intrapleural pressure (Ppl)
c. It is always negative during inspiration and positive during expiration
d. it always remains less than atmospheric pressure
during inspiration the pleural pressure drops, the transpulmonary pressure gradient widens, causing the alveoli pressure to become subatmospheric and the
what happens during normal inspiration?
1. The Ppl decreases further below Atmospheric
2. The transpulmonary P gradients Widens
3. P alv drops below that at the airway opening
As the alveoli expand, their Pressures fall below the Pressure at the airway openind this "negative" trasrespiratory pressure gradient causes air to flow from the airway opening to the alveoli increasing their volume.
During normal tidal ventilation, the trasnpulmonary pressure gradient (Palv-Ppl) reaches its maximun value at what point in the cycle?
at this point, called end-inspiration, alveolar pressure has returned to 0 and the transpulmonary pressure gradient reaches its maximal value (for a normal breath) of approximately -10cm h2o
During expiration, why does gas flow out from the lungs to the atmosphere?
a. P alv is less than at the airway opening
b. P alv is the same as at the airway opening
c. P alv is greater that at the airway opening
d. airway pressure is greater that P alv
As expiration begins the thorax recoils and P Pl starts to rise. As the pleural pressure rises, alveolar pressure also increases, the transpulmonary pressure gradient narrows and the alveoli begging to deflate. As the alveoli become smaller, alveolar pressure exceeds that at the airway opening.
What forces must be overcome to move air into the respiratory system
1. Tissue movement
2. Elastic forces of lung tissue
3. Airway resistance
4. Surface tension forces
Elastic forces involve the tissue of the lungs and the thorax, along with surface tension in the alveoli. Frictional forces include resistance caused by gas flow and tissue movement during breathing
What term is used to note the difference between inspiratory lung Volume and expiratory lung volume at any given pressure?
Deflation of the lung does not follow the inflation curve exactly. During deflation, lung volume at any given pressure is slightly greater that it is during inflation. This difference between the inflation and deflation curve is call hysteresis.
What is the effect of surface tension forces in the air-filled lung?
1. It increases the elastic recoil of the lung (promoting collapse)
2. It makes the lung harder to inflate than if it were filled with fluid
3.it decreases the lung's elasticity as volume increases
1 & 2
Less pressure is needed to inflate a fluid-filled lung to a given volume. This phenomenon indicates that a gas-fluid interface in the air filled lung changes its inflation-deflation characteristics. The recoil of the lung is therefore a combination of tissue elasticity and these surface tension in the alveoli. During inflation, additional pressure is needed to overcome surface tension forces .
The presence of surfactant in the alveoli tends to do which of the following?
A. decrease compliance
b. decrease surface tension
c. increase elastance
d. increase resistance
A phospholipids called pulmonary surfactant lowers surface tension in the lung
how is compliance computed?
a. Change in pressure / change in flow
b. Change in pressure / change in Vol
c. Change in Volume / Change in flow
d. Change in Volume / Change in pressure
compliance of the lung (C L) is define as Volume change per unit od Pressure change. It is usually measure in L/cm H2O
normal lung compliance is approximately which of the following?
a. 0.01 L/ cm H2O
b. 0.20 L/ cm H2O
c. 2.00 L/ cm H2O
d. 10.00 L/ cm H2O
Compliance of a healthy adult lung averages 0.2 L/cm H2O or 200 ml/cm H2O
A lung that loses elastic fiber (as in emphysema) would exhibit which of the following characteristics?
a. decrease airway resistance
b. decrease pulmonary vascular resistance
c. increased airway resistance
d. increase pulmonary compliance
increase compliance ressults primarily from loss of elastic fibers, which occurs in emphysema
a fibrotic lung would exhibit which of the following characterics?
a. decreased airway resistance
b. decrease lung compliance
c. decrease PVR
d. decrease surface tension
the compliance curve of the patient with pulmonary fibrosis is flatter than the normal curve,shifted down and to the right. as a result, there is a smaller volume changes for any given pressure change (decrease compliance).
what occurcs at a lung volume equivalent to the functional residual capacity (FRC)?
1. the forces of the chest wall and lungs are in balance.
2. chest wall expansion is offset by the lung contraction.
3. opposing chest-wall-lung forces generate negative Ppl
1, 2 & 3
the lung-chest wall system may be compared with two springs pulling against each other. the chest wall spring tends to expand, whereas the lung spring tend to contact. at the resting level, the forces of the chest wall and lungs balance. The tendency of the chest wall to expand is offset by the contractile force of the lungs. this balance of forces deterrmines the resting lung volume, or FRC. the opposing forces between the chest wall and the lungs are partially responsible for the subatmospheric pressure in the intrapleural space.
at approximately what point during maximum inspiration does the chest wall reach its natural resting level?
a. about 30% of the VC
b. about 40% of the total lung capacity (TLC)
c. about 70% of the VC
d. about 90% of the VC
when lung volumes nears 70% of the VC, the chest wall reaches its natural resting level.
Exhalation below the resting level requires active muscular effort in order to overcome what tendency?
a. the airways to collapse
b. the alveoli to expand
c. the chest wall to expand
d. the lungs to expand
in order to exhale below the resting level FRC muscular effort is require to overcome the tendency of the chest wall to expand
in order to inspire to a lung volume greater tha about 70% of TLC the inspiratory muscles must overcome:
a. the recoil of the lungs
b. the recoil of both the lungs and the chest wall
c. the recoil of both the chest wall
d. the recoil of the alveoli
at the beginning of the breath, the tendency of the chest wall to expand facilitates lung expansion. when lung volume nears 70% of the VC , the chest wall reaches its natural resting level. in order to inspire to a lung volume greater than about 70% of tlc , the inspiratory muscles must overcome the rcoil of both the lungs and the chest wall.
Total lung-thorax compliance in normal subjects is about what level?
a. 0.1 L/ cm H2O
b. 0.2 L / cm H2O
c. 1.0 L / cm H2O
d. 2.0 L / cmH2O
in healthy adults, the compliance of the lungs and chest wall are approximately equal at .2 L / cm H20. however, because the lungs are containes with in the thorax, the two systems acts as springs pulling against each other. this reduces the compliance of the system to approximately half that of the individual components, or 0.1 L/ cm H2O. impendance to ventilation by the movement of gas through the airways is called airway reistance..
what is the term for the impendance to ventilation caused by the movement of gas through the conducting system of the lungs?
a. airway resistance
b. lung compliance
c. surface tension
d. tissue elastance
how is airway resistance (Raw) computed ?
a. Change in pressure/ change in volume
b. change in pressure/ flow
c. change in volume * change in pressure
d. change in volume / change in Pressure
airway resistance (Raw) is the ratio of driving pressure responsible for gas movement to the lung flow of the gas.
normal Raw is approximately which of the following?
a. 0.1 to 0.2 cm H2O/ L / sec
b. 0.5 to 2.5 cm H2O / L / sec
c. 15.0 to 20.0 cm H2O / L / sec
d. 20.0 to 25.0 cm H2O / L / sec
- airway resistance in healthy adults ranges from approximately 0.5 to 2.5 cm H2O/ L /Sec
which of the following factors affest the Raw?
1. pattern of gas flow
2. characteristics of the gas being breathed
3. diameter and lengh of the airways
4. variations in lung compliance
1, 2, 3
laminar flow is affected by gas flow, viscosity of the gas, tube radious and length. turbulent flow is most affected by gas density and viscosity, linear velocity and tube radius.
according to Poiseuille's law, which of the following statements are tru is we wish to maintain a constant flow of gases?
a. alveolar recruitment has its greatest effect on flow
b. halving the tube radius will require a 16-time increase in driving pressure
c. large jumps in driving pressure are need to overcome airway narrowing
d. the driving pressure varies directly with the airway circumference
for a gas flow to remain costant,delivery pressure must vary inversely with the fourth power of the airways radius. reducing the radius of the tube by half requires a 16-fold pressure increase to maintain a constant flow. to maintain ventilation in the presence of narrowing airways, large increases in driving pressure may be needed. the energy necessary to generate these pressures can markedly increase the work of breathing.
most of the in pressure due to frictional resistance to gas flow occurs in what region?
a. nose, mouth and large airways
b. respiratory bronchioles
c. terminal bronchioles
d. terminal respiratory units.
approximately 80% of the resistance to gas flow occurs in the nose, mouth and large airways where flow is mainly turbulant
which of the following statements about Raw is true?
a. the greater the lung volume, the greater is the Raw.
b. the greater the lung volume, the less is the Raw.
c. as lung volume drecreases toward RV the Raw drops.
d. as lung Volume increase toward TLC, the Raw rises.
the increase in airway diameter with increasing lung volume decreases airway resistance.
In healthy individuals, what may lead to airway collapse?
a. increased lung recoil
b. significantly decreased surfactant
c. maximal inspiration to tlc
d. forced exhalation to RV
in airways of healthy subjects airway collapse occurs only with forced exhalation and at low lung volumes
which of the following statements about the equal pressure point (epp) is true?
a. as gas travels from the EPP to the mouth, greater expiratory effort increases flow
b. at the EPP, pressure inside the airway exceeds Ppl
c. the EPP normally occurs at volumes greatly below the FRC
d. upstream from the EPP( toward the alveoli), Ppl exceeds pressure in the airway.
at some point along the airways the pressure inside equals the pressure outside in the pleural space. the point is refferes to as the EPP. downstream from this point, Pleural pressure exceeds the airway pressure. the resulting positive transmural pressure gradient causes airway compression and can lead to actual collapse. airway compression increases expiratory airway resistance and limits flow. in airways in healthy subjects, the EPP occurs only with forced exhalation at low lung volumes
for healthy individuals at rest, which of the following statements about exhalation is true?
a. exhalation will be passive, due ti inspiratory stored potential energy
b. exhalation wil only require 40% of the energy expended for inspiration
c. Exhalition will be the result of accessory respiratory muscle use
d. exhalation will generally take half the time of inspiration.
during normal quiet breathing, inhalation is active and exhalation is passive. the work is recovered from potential energy " stored" in the expanded lung thorax during inhalation.
in traditional physicsl terms, how is work defined?
a. work * distance
b. force * time
c. mass * acceleration
d. mass * force
work= force * distance
which of the following formulas is used to compue the mechanical work of breathing?
a. change in pressure / flow
b. change in pressure * change in flow
c. change in pressure * change in Volume
d. change in volume / change in pressure
the mechanical work of breathing can be calculated as the product of the pressure across the respiratory sistem and the resulting changes in volume
why is the total mechanical work of breathing difficult to assess during spontaneous breathing?
a. most of the volunterr subjects cannot understand the procedures used
b. respiratory muscle activity contributes to inflation resistance
c. the respiratory muscle ( diaphragm, etc.) must be paralyzed
d. the subjects used to make the measurements must be unconscious.
the mechanical work of breathing cannot be measured easily during spontaneous breathing. this is because the respiratory muscles contribute to the resistance offered by the chest wall.
on inspecting a volume-pressure curve of the lungs and thorax an increase in the mechanical work of breathing above normal would always be indicated by which of the following?
a. decrease in the area of the volume-pressure curve
b. decrease in the slope of the volume-pressure curve
c. increase in the are of the volume-pressure curve
d. increase in the slope of the volume-pressure curve
the larger the are defined by the pressure and volume changes, the greater is the amount of work being done.
in health, about what proportion of the total work of breathing is attributable to frictional resistance to gas and tissue movement?
in healthy adults, approximtely two thirds of the work of breathing can be attributed to elastic forces opposing ventilation. the remaining third is a result of frictional resistance to gas and tissue movement.
on inspecting a volume-pressure curve for a patient with restrictive lung disease, which of the following abnormalities would you expect to find?
1. decrease in the slope of the volume -pressure curve
2. increase in the area of the volume-pressure curve
3. positive Ppl during exhalation
in restrictive lung disease, the area of the volume -pressure curve is greater because the slope of the static component (compliance) is less than normal.
which of the following factors would tend to increase the elastic component of the work of breathing
1. decrease compliance of the lung or thorax
2. high frequencies of breathing
3. increased Vt
when changing from quiet breathing to exercise ventilation, healthy subjects adjust their tidal Volumes and breathing frequencies to minimize the work of breathing . similar adjustments occurs in individuals who have lung disease. patients with " stiff lungs" , decreased compliance, have increased elastic work of breathing. large tidal volumes also increase the elastc component
which of the following factors would tend to increase the frictional component of the work of breathing?
1. decrease compliance of the the lungs or thorax
2. high frequencies of breathing
3. increase Raw
In healthy individual, the mechanical work of breathing depends on the patter of ventilation. high breathing rates ( and hence, high flows) increase frictional work. patients who have airway obstruction (i.e, increased Raw) also experience increased frictional work of breathing.
in individuals with disorders characterized by an increased frictional work of breathing, such as emphysema, which of the following breathing patterns results in the minimum work?
a. rapid and deep breathing
b. rapid and shallow breathing
c. slow and deep breathing
d. slow and shallow breathing
breathing slowly and using pursed lip breathing during exhalation minimize airway resistance and thus work of breathing in patients with emphysema.
all of the following will cause an increase in the pressure energy requires for inspiration EXCEPT which one?
a. increased compliance
b. increased flow
c. increased resistance
d. increased volume
high flows and increased Raw increase frictional work. Large tidal volumes increase the elastic component of work. increased compliance will decrease the elastic component of work and thus is the one exception to an increased energy demand.
a normal individual, what is the oxygen cost of breathing as a percentage of the bodys total oxygen consumption?
the oxygen cost of breathing in healthy individuals averages fro 0.5 to 1.0ml oxygen per liter ventilation. given a normal ventilation of 5 L/min, the oxygen cost of breathing would be 2.5- 5 ml out of the total oxygen consumption of 250ml/min. this represent less than 5% of the oxygen consumption of the body.
compared to a normal individual, when a pt with a severe obstructive impairment such as emphysema increases ventilation, which of the following occurs?
a. carbon dioxide production falls as anaerobic metabolism increases
b. oxygen consumption increases at faster rate than normal
c. oxygen consumption rises faster than carbon dioxide production
d. the anaerobic threshold is reached later than normal
In the presence of pulmonary disease (either obstructive or restrictive), the oxygen cost of breathing may increase dramatically with increasing ventilation. In an obstructive disease such as emphysema, increased ventilation causes the oxygen consumption of the respiratory muscles to increase rapidly
Regional factors affecting the distribution of gas in the normal lung result in which of the following?
A. more ventilation goes to the apexes and lung periphery
b. more ventilation goes to the apexes and lung core
c. more ventilation goes to the bases and lung core
d. more ventilation goes to the bases and lung periphery
In upright individuals, these factors direct more ventilation to the bases and periphery of the lungs
Which of the following statements are true about pressure differences in the upright lung?
1. Ppl increases from lung apex to base
2. The apical alveoli resting volume is less than at the base
3. transpulmonary pressure gradient is greatest at the apex
In an adult-size lung (approximately 30 cm from apex to base), pleural pressure at the apex is approximately -10cm H2O. At the base, pleural pressure is only -2.5 cm H2O. Because of these differences the transpulmonary pressure gradient at the top of the upright lung is greater that it is at the bottom.
During normal inspiration, which of the following occurs?
A. alveoli at the apexes expand less than those at the bases
b. alveoli at the apexes expand more than those at the bases
c. alveoli at the bases expand less than those at the apexes
d. central alveoli expand more than those at the periphery
Despite their higher volume, alveoli at the spices expand less during inspiration then alveoli at the bases or periphery. This is due to their respective positions on the pressure Volume curves. The apical alveoli are on the flatter or less compliant portion of the curve and thus for any change in pressure there is only a small change in volume. The alveoli in the lung base are on the steep part of the curve, so even small changes in pressure results in comparatively large changes in volume.
In a normal individual lying on the right side(right side down), which of the following conditions would be true?
A. both lungs would receive nearly equal ventilation
b. left lung would receive the most ventilation
c. the right lung would receive the most ventilation
d. There is inadequate information to make a decision
Lying on the side causes more ventilation to go to whichever lung is lower.
Given a constant resistance, how will increasing the compliance of the lung unit altar gas movement into and out of the alveolus?
A. both filling and emptying will be slower
b. the alveolus will fill and empty more slowly
c. the alveolus will fill more quick but empty more slowly
d. the alveolus will fill more slowly but empty more quickly
Lung units with high compliance have less elastic recoil that normal. These units fill and empty more slowly than normal units.
Which of the following statements apply to a lung unit with higher resistance than normal?
a. a given volume change will require less of a pressure change.
b. it will fill and empty more rapidly than a normal lung unit
c. there will be less volume change for a given pressure change
d. volume to this area will remain the same under all conditions
If the airway is obstructed, high resistance to gas flow can occur in a local area. The pressure drop across the obstruction may be substantial. Less driving pressure is available for alveolar inflation; thus there is less alveolar volume change.
Which of the following formulas are used to compute the time constant of a lung unit?
A. change in pressure *n flow
d. resistance* compliance
The time constant is simply the product of each units compliance & resistance
Which of the following lungs units would empty and fill most slowly?
A. a unit with high resistance and high compliance
b. unit with high resistance and low compliance
c. unit with low resistance and high compliance
d. unit with low resistance and low compliance
Lung units have a short time constant when resistance or compliance is low. Lung units with short time constant fill empty more rapidly than those with normal compliance and resistance. The inverse also holds true. Those units with a high compliance will fill and empty the most slowly.
For a given transpulmonary pressure gradient and inflation time, which of the following lung unit would exhibit the greatest change in volume?
A. unit with high resistance and low compliance
b. a unit with high resistance is a normal compliance
c. a unit with normal resistance and low compliance
d. a unit with normal resistance and normal compliance
The ventilation going to lung units with either long or short time constant is less that that receive by unit with normal compliance and resistance
In pts with small-airway disease breathing at higher than normal frequencies, what will not happen?
A. dynamic compliance drops
b. oxygen consumption decreases
c. the distribution of ventilation worsens
d. the work of breathing increases
Compliance of the lung appears to decrease s breathing frequency increases. This phenomenon is called frequency dependence of compliance. Compliance measured during dynamic breathing is dynamic as it includes pressures changes creates by resistance to airflow. If dynamic compliance decreases as the respiratory rate increases, some lung units must have abnormal time constants. Any stimulus to increase ventilation, such as exercise, may redistribute inspired gas. Mismatching of ventilation and perfusion can result in hypoxemia severely limiting and individual ability to perform daily activities. In addition the increased breathing frequency and decreased dynamic compliance may result in significant increases in oxygen consumption.
What is the gas that is wasted during normal ventilation called?
A. alveolar ventilation
b. bronchial ventilation
c. conducting ventilation
d. dead space ventilation
For each breath, the gas left in the conducting tubes does not participate in the gas exchange and is, in effect, wasted. Similarly, regional differences in ventilation cause some gas that does reach the alveoli to be wasted. This occurs in alveoli that have little or no perfusion. Ventilation occurring without perfusion defines dead space
Blockage of the pulmonary arterial circulation to a portion of the lung would cause which of the following ?
A. decrease in anatomical dead space
b.decrease in physiologic dead space
c. increase in alveolar dead space
d. increase in anatomical dead space
Pulmonary embolus blocks a portion of the pulmonary circulation. This obstructs perfusion to ventilated alveoli, creating alveolar dead space .
In what portion of the lung does alveolar dead space normally occur?
c. middle portions of the lungs
d. terminal respiratory units
in the normal upright subject at rest, alveoli at the apices of the lungs have minimal or no perfusion,and thus contribute to the total volume of dead space ventilation.
what is the formula for alveolar ventilation?
in clinical practice measuring the physiologic dead space ventilation is achieved by using which formula?
b. modified bohr equation
c. modified shunt equation
d. reynolds equation
the ratio is then calculated using a modified form of bohr equation, which assumes that there is no CO2 in inspired gas
in normal individuals, approximately what fraction of the Vt wasted ventilation (does not participate in gas exchange)?
in the healthy adult, physiologic dead space is approximately one third of the tidal volume.
which of the following diseases or diseases or disorderd is most likely to result in an increased Vd/Vt ratio?
c. pulmonary embolus
d. pulmonary fibrosis
Vd/Vt increases with diseases that cause significant dead space, such as pulmonary embolism.
what will happen if the rate of breathing increases without change in total minute ventilation?
a. the dead space ventilation per minute will decrease.
b. the VA per minute will decrease
c. the VA per minute will increase
d. the VA per minute will remain constant
high respiratory rates and low tidal volumes result in a high proportion of wasted ventilation per minute.
what Ventilatory patterns would result in the most wasted ventilation per minute (assume constant physiologic dead space?
high respiratory rates and low tidal volumes result in a high proportion of wasted ventilation per minute (low Va)
what ventilatory pattern would result in the greatest VA per minute?
in general, the most efficient breathing pattern is slow, deep breathing.
how can the body effectively compensate for an increased Vd ?
a. decrease drive to breath
b. decrease respiratory rate
c. increased respiratory rate
d. increased tidal volume
effective compensation for increases Vd requires and increased tidal volume
under resting metabolic conditions, how much CO2 does a normal adult produce per min?
a. 150 ml/min
b. 200 ml/min
c. 250 ml/min
d. 300 ml/min
under resting metabolic conditions, a normal adult produces approximately 200 ml of CO2 per min.
for CO2 levels to remain constant during exercise, which of the following factors must be elevated?
a. alveolar ventilation
b. dead space ventilation
d. v/q ratio
the partial pressure of CO2 in the alveoli and blood is directly proportional to its production of CO2 and inversely proportional to its rate of removal by alveolar ventilation
hypoventilation is defined as
a. decreased tidal volume
b. low blood oxygen level
c. very slow respiratory rate
d. elevated blood carbon dioxide level
ventilation that does not meet metabolic needs (resulting in respiratory acidosis) is termed '" hypoventilation" . hypoventilation is indicated by the presence of an elevated PaCO2.
what is ventilation that is insufficient to meet metabolic needs called?
- ventilation that does not meet metabolic needs (resulting in
- respiratory acidosis) is termed '" hypoventilation" . hypoventilation is
- indicated by the presence of an elevated PaCO2.
a patient has a Pco2 of 56 mm hg. based on this information, what can be concluded?
a. the pt is hyperventilating
b. the patient is hypoventilating
c. the pts breathing rate is fast
d. the pt Vt is low
ventilation that does not meet metabolic needs 9 resulting in respiratory acidosis) is termed hypoventilation. hypoventilation is indicated by the presence of an elevated PaCO2 . if alveolar ventilation increases, the lungs may remove carbon dioxide faster than it is being produced.in this case, PaCO2 will fall below its normal value of 40 mm hg, and pH will rise (respiratory alkalosis)
given a constant carbon dioxide production, how will changing the level of VA affect the PaCO2?
a. a decrease in VA will decrease PaCO2
b. an increase in VA will decrease PaCO2
c. an increase in VA will increase PaCO2
d. PaCo2 is unaffected by changes in VA
what is ventilation in excess of metabolic needs called?
Ventilation in excess of metabolic needs is termed hyperventilation.
what is the normal increase in ventilation that occurs with increased metabolic rates called?
the increase in ventilation that occurs with increased metabolic rates called hyperpnea.
what is the single best indicator of the adequacy or effectiveness of VA?
All of the following happen at the beginning of inspiration, except:
a. inspiratory muscles expand thorax
b. alveolar expansion decreases Palv below Zero.
c. Alveolar expansion increase palv above zero
d. alveolar filling slows as Palv approaches Pao
for spontaneously breathing subject, in the beginning of inspiration, PA is subatmospheric compared to PAO causing air to flow into the alveoli ( alveolar expansion decreases palv below zero)
all of the following are correct about opposition ventilation, except:
a. elastic and collagen fibers provide resistance to lung stretch.
b. with changes in traspulmonary pressure, all of the applied pressure opposes elastic forces
c. the elastic properties if the lungs and chest wall opposed inflation.
d. a small amount of pressure causes greater stretch until maximum inflation is reached
in the respiratory system, inflation stretches tissue. the elastic properties if the lungs and chest wall oppose inflation. to increase lung volume, pressure must be applied. greater pressure causes greater stretch until maximum inflation is reached.
where is Raw said to be the highest in the airway of the human body?
a. terminal bronchioles
c. left lower lobe
d. nose, mouth and large airways
approximately 80% of the resistance to gas flow occurs in the nose, mouth, and large, airways where flow is mainly turbulent.only about 20% of the total resistance to flow is attributable to airways smaller than 2 mm in diameter, where flow is mainly laminar
which of the following causes gas to flow into and out of the alveoli during breathing?
transrespiratory pressure gradient causes gas to flow into and out of the alveoli during breathing.
what is used for setting optimal PEEP on a ventilator?
a. pressure volume curve
b. flow- volume curve
c. patients height weight
d. the disease state the pt is in
pressure volume curve is used for setting optimal PEEP