Lung volumes and mechanics Flashcards
What is spirometry and how does it work
is a measurement of lung volumes by breathing air in and out using the spirometer (spirogram); when the subject inhales air moves into the lungs;the volume of the bell goes up and pen rises on the tracing
What is residual volume
the volume of air remaining in the lungs after a maximal exhalation
What is expiratory reserve volume
the maximal volume of air that can be exhaled from the end-expiratory position
What it tidal volume
that volume of air moved into or out of the lungs during quiet breathing (VT indicates a subdivision of the lung; when tidal volume is precisely measured, as in gas exchange calculation, the symbol VT or VT is used.)
What is inspiratory reserve volume
the maximal volume that can be inhaled from the end-inspiratory level
What is the equation to determine the max volume of exhalation
vital capacity= tidal volume + inspiratory reserve volume + expiratory reserve volume
What is the equation to determine the lung volume at the end of exhalation
Functional residual capacity: the volume in the lungs at the end-expiratory position
functional residual capacity= residual volume + expiratory reserve volume
Which capacities and volume can not be measured by spirometry
residual volume
What happens to tidal volume during exercise
it increases
How is contraction of respiratory muscles and pressure difference connected
the muscles create the gradients or pressure differences that create force for airflow in and out of alveoli
During quiet breathing what controls the air pressure
activity of the diaphragm
Explain the steps of the diaphragm changes during breathing
At rest, the diaphragm is relazed
Next, the diaphragm contracts and the thoracic volume increase
As the diaphragm relaxes, thoracic volume decreases
What are three air pressures important during breathing
atmospheric pressure
alveolar pressure
intrapleural pressure
What is atmospheric pressure
noted as P(atm) is the pressure outside the body
What is alveolar pressure
noted as P(alv) its the pressure inside alveoli
What is intraplural pressure
noted as P (ip) its the pressure inside the pleural cavity
What is normal sea level atmospheric pressure; but for these purposes what is it designated
normal absolute atm is 760 mmHh @ sea level
for this case it designated as 0 mmHg
What does static condition mean
there is no airflow and both atmospheric and alveolar pressure are 0 mmHg
What is intrapleural pressure (usually, give amount)
the intrapleural pressure is less than zero usually between -2 and -5mmHg but can become positive during forceful expiration
What is the alveolar pressure at the end of a quiet expiration or FRC
zero which is FRC
What is meant by translung pressure/ alveolar distending pressure
its the difference between alveolar and intraplural pressure; force that inflate the lungs
What is need to initiate airflow during inspiration
the pressure in the alveolar must be lower than the atmospheric pressure
What happens parietal pleura as the diaphragm contracts
the parietal pleura is pulled outward
What causes the intrapleural pressure to drop; and what law does this follow
the volume of the intrapleural goes up and the pressure goes down to -8mmHg
Explain Boyles law
it states that pressure multiplied by volume equals a constant; in other words volume and pressure are inversely proportional to each other as one increases the other decreases
What happens to collisions in Boyles law
decreasing volume increases collisions and increases pressure
How does the lowering intrapleural pressure impact chest expansion and what happens from there
after intrapleural pressure drops because of chest expansion, the visceral pleural is pulled out and this increases the alveolar volume and lowers the pressure in the alveoli to -1 mmHg
What causes the air to flow into lungs
the pressure in the alveoli is lower than the pressure in the atmosphere
Explain the respiratory cycle and pressure
- halfway through inspiration the pressure in alveoli is at lowest and airflow is at highest
- the end of inspiration, the airflow will stop because the pressure and atmosphere is equal 0 mmHg
- The pressure in intrapeural space is -8mmhg @ end of inspiration
What is translung pressure and how does it vary during breathing
its the difference between alveolar pressure and intrapleural pressure; it increases during inspiration
What causes expiration
the alveolar pressure must be higher than the atmospheric pressure
Why are force expiration done and what is used to complete them
to increase ventilation, needs muscle work and expiratory reserve volume is used
What drives air out of the lungs during quiet or passive expiration
recoil of alveolar elastic fibers and surface tension
What else can help with passive lung expiration
chest elastisity can also help with passive lung expiration
Define passive expiration and does this work
relaxation of inspiratory muscle cause a slight decrease in thoracic volume and increases intrapleural pressure from -8 to -5mmHg builds up the alveolar pressure to 1mmHg and air flows out
What is pneumothorax
collapsed lung; more air goes into plural cavity making the lung collapse
What is the alveolar distending force in pneumothorax
it will be more negative (?) because there is mrore pressure in the intrapleural space
Describe according to the diagram what happens during pneumothorax
- something punches a hole in lungs- knife(maybe)
- the intrapleural space is broken open and air flows inside
- the lung collapses to unstretched size
- the rib cage will expand slightly
What is an interesting connection between pneumothroax and music
loud damage can cause lungs to collapse
What are the signs of pneumothroax
shortness of breath, chest pain, dyspnea
What are the treatments for pneumothroax
aspiration of chest tube
can recover spontaneously
What is throracstomy
incision of the chest wall, with maintenance of the opening for drainage
What are the causes of pneumothroax
trauma, lung disease, inhalation of toxic substances
What is tension pneumothrorax
opening that allows air to enter the pleural space functions as a one way valve, allowing more air to enter with every breath but none to escape
What can tension pneumothorax lead to
mediastinum and trachea may shift toward the intact lung—EMERGENCY
How much effort is required to stretch the lungs
it depends on lung compliance
the equation is compliance= change in lung volume/ change in tl
If the lung compliance is high what does that mean
lung expands easily
If lung compliance is low what does that mean; what can be done
lung resist expansion; need more muscle work to inflate lungs
What are the characteristics of healthy lungs
ample compliance and sufficient elasticity(that it will expand and return to normal form)
What factors does lung compliance depend on
surfactant which lowers surface tension of alveolar fluid
What forces help bring the alveolar inward
natural recoil (elastance) and surface tension
What is surfactant and what produces it
a mixture of lipids (dipalmitoil phosphatidylcholine)
made by type II pneumocytes
What is surface tension, what are its units, and what does it do
nN/m
- lower the surface of air-fluid interface
- will close alveoli
What how does surfactant impact surface tension
it lowers surface tension
in addition it increases lung compliance
decrease work inspiration
helps prevent collapse of small airways
How does surfactant work, refer to diagram also
disrupts the cohesive forces between water molecules @ air interface- b/c alveoli are lined with a thin film of water
What is surfactant insufficiency
decreases lung compliance, collapses small airways, air is trapped in local alveoli and not ventilated
What is infant respiratory distress
its a blood oxygen deficiency; hypoxemia found in about 10% of premature births
What are the signs and symptoms of IRDS
tachypnea, tachycardia, expiratory grunting, flaring of the nostrils and cyanosis during breathing efforts
What famous people were effects by IRDS
patrick kennedy died of RDS 34 weeks after gestation in 1963
Name some different patterns of ventilaton
eupnea hyperpnea hyperventilation tachypenea dyspnea apnea
What is eupnea
normal quiet breathing
What is hyperpnea
high frequency and or volume in response to high metabolism (exercise)
what is hyperventilation
high frequency and volume with increased metabolism (emotions)
What is hypoventilation
low frequency/volume (shallow breathing, restrictive disease)
What is tachypnea
rapid breathing, high rate/low volume (panting)
What is dyspnea
shortness of breath
What is apnea
cessation of breathing
What is notable about child development and infant respiratory distress
in the last stages of pregnancy from 34-37 weeks the pneumocytes II start producing surfactant; when an infant is born prematurely, the lungs don’t have enough surfactant formed yet; therefore the surface tension is high and the lung compliance is low
How does deficiency in surfactant effect the body
small bronchioles tend to collapse, ventilation of local alveoli is low despite increased respiratory muscle contraction
What can be done to deal with surfactant deficiency
positive pressure must be applied by a ventilator to areas lack ventilation atelectasis
How can IRDS be treated
artificial surfactant (aersol), steroids that stimulate pneumocytes II
babies will be in special incubators with high oxygen content; high oxygen without surfactant may affect the retina and cause blindness
What is acute respiratory distress syndrome, who does it affect primarily
affects adults; can involve pulmonary capillary leak due to damage of the alveolar-capillary interface
What can acute respiratory distress be caused by
lung inhalation injury (noxious gases)
inflammation (sepsis-blood bacterial infection)
aspiration of gastric contents
What happens with fluid accumlation in the alveoli and interstitium during acute respiratory distress
edema, atelectasis and slow diffusion due to increased distance for oxygen
What are the major symptoms of acute respiratory distress
shortness of breath, impaired gas exchange, and hypoxemia
What also reduces lung compliance
fluid plasma infiltrates alveoili and lower lung compliance
what are other causes of pulmonary edema
pulmonary hypertension, congestive heart failure, or hypovolemia
What is the treatment of pulmonary edema
diuretics like furosemide
What is restrictive ventilatory disease
can not get air in, restricts lung expansion, lowers lung volumes and capacities
What overall is the result of restrictive ventilatory disease
decrease alveolar compliance due to lung damage w/ or without fluid accumulation and reduces oxygen transport into the blood stream; blood oxygen is low
What is restrictive disease
stiff lung; that decreases lung compliance
What are types of pulmonary restrictive disease
lung problems
accumulation of fluid in the lung- pulmonary edema
lung tissue destruction- fibrosis, tuberculosis
pleural effusion- fluid in the pleural space caused by lung cancer, infections, trama
What is thoracocentesis
an invasive procedure to remove fluid of air from the pleural space for diagnostic or therapeutic purposes with a cannula or hollow needle
What if fluid constantly accumulates in a local pleural space
look up
What is pleural scleosis with induction pleurodesis
fusion of visceral and parietal lung pleura
What are typical sclerosing agents
talc and antibiotics like doxycyclin, erythromycin, etc
What do disease of the nervous system and muscle disease also lead to
cause reduced lung mobility and restrictive pattern of ventilation
Give some examples of disease that lead to restrictive pattern of ventilation
myasthenia gravis, gillian-barre syndrome, diaphragm paralysis, and broken ribs
What is the only exception of lung volumes that will no be reduced by restrictive ventilatory diseases
residual volume
How extra thing is needed for a forceful expiration
expiratory muscle work- use of ERV
What lung measurement do neuromuscular defecits reduce
ability to breath out so..expiratory reserve volume, tidal volume, and inspiratory reserve volume
