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201 Cards in this Set

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1. The primary purpose of the respiratory system is
Gas exchange
Gas exchange involves the transfer of
i. oxygen (O2) and carbon dioxide (CO2)


between


ii. the atmosphere and the blood

The respiratory system is divided into HOW MANY PARTS?
a. the upper respiratory tract

b. The lower respiratory tract

1. The upper respiratory tract includes WHAT
a. nose

b. mouth


c. pharynx


d. epiglottis


e. larynx


f. trachea

WHY do aveoli have anatural tendency to collapse
Because alveoli are unstable
3. Alveolar cells secrete what
surfactant

what is sarfactant

4. Surfactant is a lipoprotein that lowers the surface tension in the alveoli

what does Surfactant do

It reduces the amount of pressure needed toinflate the alveoli and makes them less likely to collapse

what is the name of the slightly larger breath that each person takes after every five or six breaths

Sigh

that does the sign do

This sighstretches the alveoli and promotes surfactant secretion
What happens When not enough surfactant is present,
the alveoli collapse
8. The term atelectasis refers towhat?

collapsed, airless alveoli
The postoperative patient is at risk for atelectasis because of what?


the effects of anesthesia and restricted breathing with pain
In acute respiratory distress syndrome (ARDS), lack of surfactant contributes to what?


widespread atelectasis
1. what are the lungs two different types of circulation
a. pulmonary



b. bronchial

2. The pulmonary circulation provides what?
the lungs with blood that participates in gas exchange
3. The pulmonary artery receives what?



and delivers it where?

deoxygenated blood from the right ventricle of the heart



and




delivers it to pulmonary capillaries that are directly connected with alveoli

The pulmonary veins do what?


return oxygenated blood to the left atrium

The left atrium delivers blood where?

to the left ventricle

where do the left ventricle pump blood to?

into the aorta

what does the aorta do with the blood

supplies the arteries of the systemic circulation
Venous blood is collected from
capillary networks of the body returned to the right atrium by way of thevenae cavae


The bronchial circulation starts with
the bronchial arteries

bronchial arteries arise from the
thoracic aorta




Deoxygenated blood returns from the bronchial circulation through the
azygos vein into the superior vena cava
The bronchial circulation provides
oxygen to the bronchi and other pulmonary tissues
The chest wall is shaped, supported, and protected by
24 ribs (12 on each side)


The ribs and the sternum do what?
protect the lungs and the heart from injury


The ribs and the sternum are called
the thoracic cage


The chest cavity is lined with
a membrane called the parietal pleura,


and the lungs are lined with
a membrane called the visceral pleura


The parietal and visceral pleurae join to form
a closed, double-walled sac


The visceral pleura does not have
any sensory pain fibers or nerve endings,

whereas the parietal pleura does have
sensory pain fiber


Therefore irritation of the parietal pleura causes
pain with each breath


The space between the pleural layers is called the
intrapleural space


Normally this space contains
20 to 25 mL of fluid


This fluid serves two purposes:
(1) It provides lubrication, allowing the pleural layers to slide over each other during breathing



and




(2) It increases cohesion between the pleural layers, thereby facilitating expansion of the pleurae and lungs during inspiration



Fluid drains from the pleural space by the
lymphatic circulation


Several pathologic conditions may cause the accumulation of greater amounts of fluid, termed
a pleural effusion


Pleural fluid may accumulate because of
blockage of lymphatic drainage (from malignant cells) or because of an imbalance between intravascular and oncotic fluid pressures, as in heart failure


Purulent pleural fluid with bacterial infection is called
empyema


The diaphragm is
the major muscle of respiration

During inspiration the diaphragm
contracts, increasing intrathoracic volume and pushing the abdominal contents downward


At the same time the external intercostal muscles and scalene muscles contract
increasing the lateral and anteroposterior (AP) dimension of the chest

This causes the size of the thoracic cavity to
increase and intrathoracic pressure to decrease, so air enters the lungs


The diaphragm is made up of
two hemidiaphragms, each innervated by the right and left phrenic nerves


The phrenic nerves arise from
the spinal cord between C3 and C5, the third and fifth cervical vertebrae


Injury to the phrenic nerve results in
hemidiaphragm paralysis on the side of the injury


Complete spinal cord injuries above the level of
C3 result in total diaphragm paralysis and dependence on a mechanical ventilator
Ventilation involves
inspiration, or inhalation (movement of air into the lungs), and expiration, or exhalation (movement of air out of the lungs)


Air moves in and out of the lungs because
intrathoracic pressure changes in relation to pressure at the airway opening


Contraction of the diaphragm and intercostal and scalene muscles increases
chest dimensions, thereby decreasing intrathoracic pressure


Gas flows from
an area of higher pressure (atmospheric) to one of lower pressure (intrathoracic)


When dyspnea (shortness of breath) occurs, neck and shoulder muscles
can assist the effort

Some conditions may limit diaphragm or chest wall movement and cause the patient to breathe with
smaller tidal volumes


What are some condition that can cause a smaller tidal volume
phrenic nerve paralysis, rib fractures, neuromuscular disease


As a result,smaller tidal volumes
the lungs do not fully inflate, and gas exchange is impaired


In contrast to inspiration, expiration is
passive


Elastic recoil is
the tendency for the lungs to relax after being stretched or expanded

.



The elasticity of lung tissue is due to the
elastin fibers found in the alveolar walls and surrounding the bronchioles and capillaries


The elastic recoil of the chest wall and lungs allows
the chest to passively decrease in volume


Intrathoracic pressure rises, causing
air to move out of the lungs


Exacerbations of asthma or chronic obstructive pulmonary disease (COPD) cause
expiration to become an active, labored process


Abdominal, intercostal, and accessory muscles scalene, trapezius assist in
expelling air during labored breathing
Compliance (distensibility) is
a measure of the ease of expansion of the lungs

This is a product of
the elasticity of the lungs and the elastic recoil of the chest wall


When compliance is decreased,
the lungs are more difficult to inflate

Examples include conditions that increase fluid in the such as
lungs pulmonary edema, ARDS, Pneumonia


Conditions that make lung tissue less elastic or distensible are
pulmonary fibrosis sarcoidosis


Condition that restrict lung movement
pleural effusion


Compliance is increased when
there is destruction of alveolar walls and loss of tissue elasticity, as in COPD
Oxygen and carbon dioxide move back and forth across the alveolar-capillary membrane by
diffusion






Diffusion continues until
equilibrium is reached


The lungs’ ability to oxygenate arterial blood adequately is assessed by
examination of the partial pressure of oxygen in
arterial blood (PaO2) and arterial oxygen saturation (SaO2)


Oxygen is carried in the blood in two forms:
dissolved oxygen and hemoglobin-bound oxygen


The PaO2 represents
the amount of oxygen dissolved in the plasma and is expressed in millimeters of mercury (mm Hg)


The SaO2 is the
amount of oxygen bound to hemoglobin in comparison with the amount of oxygen the hemoglobin can carry


The SaO2 is expressed as a
percentage

if the SaO2 is 90%, this means
that 90% of the hemoglobin attachments for oxygen have oxygen bound to them
Two methods are used to assess the efficiency of gas transfer in the lung and tissue oxygenation: analysis of
arterial blood gases (ABGs) and pulse oximetry


ABGs are measured to
determine oxygenation status and acid- base balance


ABG analysis includes measurement of the
PaO2, PaCO2, acidity (pH), and bicarbonate (HCO −) in arterial blood


The SaO2 is either calculated or measured during
ABG analysis


Blood for ABG analysis can be obtained by
arterial puncture or from an arterial catheter,
Blood for ABG analysis Usually COMES FROM the
radial or femoral artery
Both techniques allow


Continuous intraarterial blood gas monitoring is also possible via
a fiberoptic sensor or an oxygen electrode inserted into an arterial catheter


An arterial catheter permits
ABG sampling without repeated arterial punctures


The normal PaO2 decreases with
advancing age

It also varies in relation to the distance
above sea level

At higher altitudes the barometric pressure is lower, resulting in
a lower inspired oxygen pressure and a lower PaO2
For the patient with a normal or near-normal cardiac status, an assessment of
PaO2 or SaO2 is usually sufficient to determine the level of oxygenation


The patient with impaired cardiac output or hemodynamic instability may have
Inadequate tissue oxygen delivery or abnormal oxygen consumption


The amount of oxygen delivered to the tissues or consumed can be
calculated


/



Blood drawn from a PA catheter is termed a mixed venous blood gas sample because
it consists of venous blood that has returned to the heart and “mixes” in the right ventricle


When tissue oxygen delivery is inadequate or when inadequate oxygen is transported to the tissues by the hemoglobin WHAT HAPPENS,
the PvO2 and SvO2 fall
Arterial oxygen saturation can be monitored noninvasively and continuously using a pulse oximetry probe on the
finger, toe, ear, bridge of the nose


The abbreviation SpO2 is used to
indicate the oxygen saturation of hemoglobin as measured by pulse oximetry SpO2 and heart rate are displayed on the monitor as digital readings


Pulse oximetry is particularly valuable in intensive care and perioperative situations, in which
sedation or decreased consciousness might mask hypoxia


SpO2 is assessed with each
routine vital sign check in many inpatient areas

Changes in SpO2 can be
detected quickly and treated


Oximetry is also used during
exercise testing and when adjusting flow rates during long-term oxygen therapy


Values obtained by pulse oximetry are less accurate if
the SpO2 is less than 70%


At this level the oximeter may display a value that is
±4% of the actual value


For example, if the SpO2 reading is 70%, the actual value can range from
66% to 74%


Pulse oximetry is also inaccurate if
hemoglobin variants are present carboxyhemoglobinmethemoglobin


Other factors that can alter the accuracy of pulse oximetry include
motion low perfusion anemia cold extremities bright fluorescent lights intravascular dyes thick acrylic nails dark skin color


If there is doubt about the accuracy of the SpO2 reading,
obtain an ABG analysis to verify the results


Oximetry can also be used to monitor SvO2
via a PA catheter


A decrease in SvO2 suggests that
less oxygen is being delivered to the tissues or that more oxygen is being consumed


Changes in SvO2 provide an
early warning of a change in cardiac output or tissue oxygen delivery


Normal SvO2 is
60% to 80%
Carbon dioxide can be monitored using
transcutaneous CO2 (PTCCO2) and end-tidal CO PETCO2) (capnography)


Transcutaneous measurement of CO2 is a noninvasive method of
estimating arterial pressure of CO2 (PaCO2)
using an electrode placed on the skin


PETCO2 is the noninvasive measurement of
alveolar CO2 at the end of exhalation when CO2 concentration is at its peak

It is used to monitor and assess trends in the patient’s
ventilatory status


Expired gases are sampled from the patient’s airway and are analyzed by a
CO2 sensor that uses infrared light to measure exhaled CO2


The sensor may be attached to an
adaptor on the endotracheal tube or the tracheostomy tube


A nasal cannula with a sidestream capnometer can be used in patients without
an artificial airway


Capnography is usually presented as a
graph of expiratory CO2 plotted against time


In the past, capnography was used mainly
intraoperatively, postoperatively, and in critical care units


Today’s monitors are portable and practical for use on
inpatient units and emergency departments


Measurement of oxygen saturation (oximetry) is primarily used to assess
for hypoxia


CO2 monitoring assesses for
hypoventilation


The use of both measures together is important in determining patients’
oxygenation and ventilatory status
A chemoreceptor is a
receptor that responds to a change in the chemical composition (PaCO2 and pH) of the fluid around it


Central chemoreceptors are located in the
medulla and respond to changes in the hydrogen ion (H+) concentration


An increase in the H+ concentration (acidosis) causes the medulla to
increase the respiratory rate and tidal volume (VT)


A decrease in H+ concentration (alkalosis) has
the opposite effect


Changes in PaCO2 regulate ventilation primarily by
their effect on the pH of the cerebrospinal fluid


When the PaCO2 level is increased,
more CO2 is available to combine with H2O and form carbonic acid (H2CO3)


This lowers the cerebrospinal fluid pH and stimulates an increase in
respiratory rate


The opposite process occurs with a decrease in
PaCO2 level


Peripheral chemoreceptors are located in the
carotid bodies at the bifurcation of the common carotid arteries and in the aortic bodies above and below the aortic arch


The peripheral chemoreceptors respond to decreases in
PaO2 and pH and to increases in PaCO2


These changes also stimulate the
respiratory center


In a healthy person an increase in PaCO2 or a decrease in pH causes an
immediate increase in the respiratory rate


The PaCO2 does not vary more than about
3 mm Hg if lung function is normal


Conditions such as COPD alter lung function and may result in
chronically elevated PaCO2 levels


In these instances the patient is relatively
insensitive to further increases in PaCO2 as a stimulus to breathe and may be maintaining ventilation largely because of a hypoxic drive from the peripheral chemoreceptors
Mechanical receptors (juxtacapillary and irritant) are located in the
lungs, upper airways, chest wall, and diaphragm


They are stimulated by a variety of physiologic factors, such as
irritants, muscle stretching, and alveolar wall distortion

Signals from the stretch receptors aid in the control of
respiration


As the lungs inflate,
pulmonary stretch receptors activate the inspiratory center to inhibit further lung expansion


This is termed the Hering-Breuer reflex, and it prevents
overdistention of the lungs


Impulses from the mechanical sensors are sent through the
vagus nerve to the brain

Juxtacapillary (J) receptors are believed to cause
the rapid respiration (tachypnea) seen in pulmonary edema


These receptors are stimulated by
fluid entering the pulmonary interstitial space
Respiratory defense mechanisms are efficient in protecting the lungs from
inhaled particles, microorganisms, and toxic gases

The defense mechanisms include
filtration of air, the mucocili- ary clearance system, the cough reflex, reflex bronchoconstric- tion, and alveolar macrophages
Nasal hairs
filter inspired air


Below the larynx, the movement of mucus is accomplished by the
mucociliary clear- ance system, commonly referred to as the mucociliary escalator


This term is used to indicate the relationship between the
secre- tion of mucus and the ciliary activity


Mucus is continuously secreted at a rate of about
100 mL/day by goblet cells and sub- mucosal glands


It forms a mucous blanket that contains
the impacted particles and debris from distal lung areas


The small amount of mucus normally secreted is
swallowed without being noticed


Secretory immunoglobulin A (IgA) in the mucus helps
protect against bacteria and viruses


Cilia cover the airways from the level of the
trachea to the respiratory bronchioles


Each ciliated cell contains approximately 200 cilia, which beat rhythmically about
1000 times per minute in the large airways, moving mucus toward the mouth


The ciliary beat is slower further down the
tracheobronchial tree


As a consequence, particles that penetrate more deeply into the airways
are removed less rapidly


Ciliary action is impaired by
dehydration

smoking


inhalation of high oxygen concentrations


infection


and ingestion of drugs such as atropine, anesthetics, alcohol, or cocaine



Patients with COPD and cystic fibrosis have
repeated lower respiratory tract infections


Cilia are often destroyed during these infections, resulting in
impaired secretion clearance



a chronic productive cough




and chronic colonization by bacteria, which leads to frequent respiratory tract infections

The cough is a
protective reflex action that clears the airway by a high-pressure, high-velocity flow of air


It is a backup for
mucociliary clearance, especially when this clearance mechanism is overwhelmed or ineffective


Coughing is only effective in removing secretions
above the subsegmental level (large or main airways)


Secretions below this level must be moved upward by the
mucociliary mechanism before they can be removed by coughing


Reflex bronchoconstriction is another
defense mechanism


In response to the inhalation of large amounts of irritating substances
the bronchi constrict in an effort to prevent entry of the irritants


A person with hyperreactive airways, such as a person with asthma, may experience
bronchoconstriction after inhalation of triggers such as cold air, perfume, or other strong odors






Because ciliated cells are not found below the level of the respiratory bronchioles, the primary defense mechanism at the alveolar level is
alveolar macrophages


Alveolar macrophages rapidly
phagocytize inhaled foreign par- ticles such as bacteria


The debris is moved to the level of the bronchioles for removal by the
cilia or removed from the lungs by the lymphatic system

Particles that cannot be adequately phagocytized tend to
remain in the lungs for indefinite periods and can stimulate inflammatory responses


Because alveolar macrophage activity is impaired by cigarette smoke, the smoker who is employed in an occupation with heavy dust exposureis at an especially high risk for
lung disease

Age-related changes in the respiratory system can be divided into
alterations in structure, defense mechanisms, and respiratory control

Structural changes include
calcification of the costal cartilages, which can interfere with chest expansion


The outward curvature of the spine is marked, espe-cially with
osteoporosis, and the lumbar curve flattens


There- fore the chest may appear barrel shaped, and the older person may need to use
accessory muscles to breathe


Respiratory muscle strength progressively declines after
age 50


Overall, the lungs in the older adult are
harder to inflate


Many older adults lose
subcutaneous fat, and bony prominences are pronounced


Within the lung, the number of func- tional alveoli
decreases, and they become less elastic


Small airways in the lung bases close earlier in
expiration


As a con- sequence, more inspired air is distributed to the lung apices and ventilation is less well matched to perfusion, lowering
the PaO2

Therefore older adults have less tolerance for
exertion, and dyspnea can occur if their activity exceeds their normal exercise


Respiratory defense mechanisms are less effective because of
a decline in both cell-mediated and humoral immunity (ability to produce antibodies)


The alveolar macrophages are less effective at
phagocytosis


An older patient has a less forceful
cough and fewer and less functional cilia


Mucous membranes tend to be
drier

Retained mucus predisposes the older adult to
respiratory tract infections


Formation of secretory IgA,
an important defense mechanism, is diminished


Swallowing is slower because of
transit time in the pharyngeal area, and there is reduced sensation in the pharynx


If the older adult patient has a super- imposed neurologic condition,
aspiration is likely


Respiratory control is altered, resulting in a more
gradual response to changes in blood oxygen or carbon dioxide level

The PaO2 drops to a lower level and the PaCO2
rises to a higher level before the respiratory rate changes


The extent of these changes in people of the same age
varies greatly


The older adult who has a significant
smoking history, is obese, and is diagnosed with a chronic illness is at greatest risk of adverse outcomes
In addition, the abrupt changes in direction of airflow that occur as air moves through the nasopharynx and larynx increase air turbulenceThis causes
particles and bacteria to contact the mucosa lining these structures Most large particles (greater than 5 μm) are less dangerous because
A catheter positioned in the pulmonary artery, termed a pulmonary artery (PA) catheter, is used for
mixed venous sampling
The overall direction of movement is from
the area of higher concentration to the area of lower concentration