SECTION 6 Problems of Oxygenation: Ventilation
27
Assessment: Respiratory System
Samantha J. Bonaduce
http://evolve.elsevier.com/Lewis/medsurg/
CONCEPTUAL FOCUS
Functional Ability Gas Exchange
LEARNING OUTCOMES
1. Distinguish the structures and functions of the upper 8. Obtain significant subjective and objective assessment
respiratory tract, lower respiratory tract, and chest wall. data related to the respiratory system.
2. Describe the processes of inspiration and expiration. 9. Perform a physical assessment of the respiratory system
3. Describe the process of oxygenation and ventilation. using the appropriate techniques.
4. Identify the respiratory defense mechanisms. 10. Distinguish normal from common abnormal findings in a
5. Discuss the significance of arterial blood gas values in physical assessment of a patient’s respiratory system.
relation to respiratory function. 11. Describe the purpose, significance of results, and nursing
6. Relate the signs and symptoms of inadequate oxygenation responsibilities related to diagnostic studies of the
to physical assessment findings. respiratory system.
7. Link age-related changes of the respiratory system to key
differences in assessment findings.
KEY TERMS
adventitious breath sounds oximetry
chemoreceptor oxygenation
compliance resistance
crackles, Table 27.6 surfactant
dyspnea tidal volume (Vt)
fremitus ventilation
mechanical receptors wheezes, Table 27.6
The primary purpose of the respiratory system is gas exchange. Upper Respiratory Tract
This involves the transfer of oxygen (O2) and carbon dioxide The upper respiratory tract includes the nose, mouth, pharynx,
(CO2) between the atmosphere and blood. While adequate perfu- epiglottis, larynx, and trachea. Air enters the respiratory tract
sion is needed to distribute O2 to the body tissues, adequate oxy- through the nose. The nose is made of bone and cartilage. It
genation depends on a healthy, functioning respiratory system. is divided into 2 nares by the nasal septum. The inside of the
nose is shaped into 3 passages by projections called turbinates.
STRUCTURES AND FUNCTIONS OF The turbinates increase the surface area of the nasal mucosa that
warms and moistens the air as it enters the nose. The internal
RESPIRATORY SYSTEM nose opens directly into the sinuses. The nasal cavity connects
The respiratory system is divided into 2 parts: the upper respira- with the pharynx. It is a tubular passageway that is subdivided
tory tract and the lower respiratory tract (Fig. 27.1). into 3 parts: nasopharynx, oropharynx, and laryngopharynx.
515
,516 SECTION 6 Problems of Oxygenation: Ventilation
Right Thyroid cartilage
Pharynx midclavicular Larynx
Nasal cavity line
Epiglottis Trachea
Larynx
Right Suprasternal notch
Trachea
mainstem Carina First rib
bronchus
Angle of
Segmental bronchi Right
Louis
upper
lobe Left
upper
Right lobe
middle
lobe
Right
Dust particle lower
Mucus lobe Left lower
Terminal Cilia lobe
bronchiole
Respiratory
bronchiole
Right anterior Midsternal
A axillary line line
Alveolar Vertebral line
duct
Goblet cell Spinal
B processes Right upper
Alveoli
lobe
Left
upper
lobe
Septa Pores of
Kohn
A
Left
Fig. 27.1 Structures of the respiratory tract. (A) Pulmonary functional lower Right
unit. (B) Ciliated mucous membrane. (Redrawn from Price SA, Wilson lobe lower
LM: Pathophysiology: clinical concepts of disease processes, ed 6, St lobe
Louis, 2003, Mosby.)
The nose protects the lower airway by warming and humidi-
fying air and filtering small particles before air enters the lungs.
The olfactory nerve, found within the mucosa of the upper part
of the nasal cavity, is responsible for the sense of smell.1
Air moves through the oropharynx to the laryngopharynx. It
then travels through the epiglottis to the larynx before moving B Scapular line
into the trachea. The epiglottis is a small flap behind the tongue Fig. 27.2 Landmarks and structures of the chest wall. (A) Anterior
that closes over the larynx during swallowing. This prevents sol- view. (B) Posterior view. (Redrawn from Thompson JM, McFarland GK,
ids and liquids from entering the lungs. The vocal cords are in Hirsch JE, et al: Mosby’s clinical nursing, ed 5, St Louis, 2002, Mosby.)
the larynx. Air passes through the glottis (the opening between
the vocal cords) and into the trachea. alveolar ducts, and alveoli. Except for the right and left main-
The trachea is a cylindrical tube about 5 inches (10 to 12 cm) stem bronchi, all lower airway structures are found within the
long and 1 inch (1.5 to 2.5 cm) in diameter. U-Shaped cartilages lungs. The right lung is divided into 3 lobes (upper, middle,
keep the trachea open but allow the adjacent esophagus to expand and lower) and the left lung into 2 lobes (upper and lower)
for swallowing. The trachea divides into the right and left main- (Fig. 27.2).
stem bronchi at a point called the carina. The carina is located at The mainstem bronchi, pulmonary vessels, and nerves enter
the angle of Louis, which is at the level of the 4th and 5th thoracic the lungs through a slit called the hilus. The right mainstem
vertebrae.2 The carina is highly sensitive. Stimulation of this area bronchus is shorter, wider, and straighter than the left mainstem
during suctioning causes vigorous coughing. bronchus. That is why aspiration is more likely to occur in the
right lung than in the left lung.
Lower Respiratory Tract The mainstem bronchi subdivide several times to form the
Once air passes the carina, it is in the lower respiratory tract. lobar, segmental, and subsegmental bronchi. Further divi-
The lower respiratory tract consists of the bronchi, bronchioles, sions form the bronchioles. The most distant bronchioles are
, CHAPTER 27 Assessment: Respiratory System 517
Conducting airways Respiratory unit Exhaled
PaO2 127 mm Hg
Bronchi, Sub- Bronchioles Alveolar PaCO2 28 mm Hg
Inhaled
Trachea segmental segmental ducts,
Non- Respiratory PaO2 159 mm Hg
bronchi bronchi respiratory alveoli
PaCO2 0.3 mm Hg
Alveolus
PaO2 100 mm Hg
PaCO2 40 mm Hg
Venous blood Arterial blood
PaO2 40 mm Hg PaO2 100 mm Hg
PaCO2 46 mm Hg PaCO2 40 mm Hg
Branchings 8 15 21-22 24 28
Fig. 27.3 Structures of lower airways. (Redrawn from Thompson JM, Fig. 27.4 Partial pressure of respiratory gases in normal respiration. The
McFarland GK, Hirsch JE, et al.: Mosby’s clinical nursing, ed 5, St Louis, pressures are shown in inhaled and exhaled air from the lungs and at
2002, Mosby.) the level of the alveoli and pulmonary venous and arterial blood vessels.
the respiratory bronchioles. The bronchioles are encircled by postoperative patient is at risk for atelectasis because of the
smooth muscles that constrict and dilate in response to various effects of anesthesia, decreased mobility, and pain, which
stimuli. The terms bronchoconstriction and bronchodilation refer can alter breathing and lung expansion. In acute respiratory
to a decrease or increase in the diameter of the airways caused distress syndrome (ARDS), lack of surfactant contributes
by contraction or relaxation of these muscles. Beyond the bron- to widespread atelectasis and collapse of lung tissue (see
chioles lie the alveolar ducts and alveoli (Fig. 27.3). Chapter 32).
The trachea and bronchi act as a pathway to conduct gases
to and from the alveoli. The volume of air in the trachea and Blood Supply
bronchi is called the anatomic dead space (Vd).3 This air does The lungs have 2 different types of circulation: pulmonary and
not take part in gas exchange. In adults, a normal tidal volume bronchial. Pulmonary circulation provides the lungs with blood
(VT), or volume of air exchanged with each breath, is about 500 that takes part in gas exchange. The pulmonary artery receives
mL (in a 150-lb man). Of each 500 mL inhaled, about 150 mL deoxygenated blood from the right ventricle of the heart and
is Vd. delivers it to pulmonary capillaries that lie directly alongside
The alveoli are the final part of the respiratory tract (Fig. the alveoli. O2–CO2 exchange occurs at this point. The pulmo-
27.3). Alveoli are small sacs in the lungs that are the primary nary veins return oxygenated blood to the left atrium, which
site of gas exchange for O2 and CO2. The adult lung has over then delivers it to the left ventricle, and into systemic circula-
300 million alveoli, each 0.3 mm in diameter. The alveoli are tion. Venous blood is collected from capillary networks of the
interconnected by pores of Kohn.4 They allow movement of air body and returned to the right atrium by way of the superior
from alveolus to alveolus (Fig. 27.1). Deep breathing promotes and inferior vena cava.
air movement through these pores and helps move mucus out Bronchial circulation starts with the bronchial arteries, which
of the respiratory bronchioles. Bacteria can also move through arise from the thoracic aorta. Bronchial circulation does not
these pores, spreading infection to previously uninfected areas. take part in gas exchange but provides O2 to the bronchi and
Alveoli have a total volume of about 2500 mL, with a surface other lung tissues. Deoxygenated blood returns from the bron-
area for gas exchange that is about the size of a tennis court. chial circulation through the azygos vein into the superior vena
Gases are exchanged across the alveolar-capillary membrane, cava.1
where the alveoli come in contact with pulmonary capillaries
(Fig. 27.4). In conditions such as pulmonary edema, excess fluid Chest Wall
fills the interstitial space and alveoli. This reduces gas exchange. The chest wall is shaped, supported, and protected by 24 ribs
(12 on each side). The thoracic cage, which consists of the ribs
Surfactant and sternum, protect the lungs and the heart from injury. The
Because alveoli are unstable, they have a natural tendency to mediastinum is the space in the middle of the thoracic cavity.
collapse. Alveolar cells secrete surfactant. Surfactant is a lipo- It contains the major organs of the chest, including the heart,
protein that lowers the surface tension in the alveoli.5 It reduces aorta, and esophagus. The mediastinum physically separates the
the amount of pressure needed to inflate the alveoli and makes right and left lungs into 2 separate compartments.
them less likely to collapse. Normally, each person takes a slightly The chest cavity is lined with a membrane called the pari-
larger breath, termed a sigh, after every 5 or 6 breaths. This sigh etal pleura. The lungs are lined with a membrane called the vis-
stretches the alveoli and promotes surfactant secretion. ceral pleura. The parietal and visceral pleurae join to form one
When there is not enough surfactant, the alveoli collapse. continuous membrane. The visceral pleura does not have any
The term atelectasis refers to collapsed, airless alveoli. The sensory (pain) fibers or nerve endings. The parietal pleura has
27
Assessment: Respiratory System
Samantha J. Bonaduce
http://evolve.elsevier.com/Lewis/medsurg/
CONCEPTUAL FOCUS
Functional Ability Gas Exchange
LEARNING OUTCOMES
1. Distinguish the structures and functions of the upper 8. Obtain significant subjective and objective assessment
respiratory tract, lower respiratory tract, and chest wall. data related to the respiratory system.
2. Describe the processes of inspiration and expiration. 9. Perform a physical assessment of the respiratory system
3. Describe the process of oxygenation and ventilation. using the appropriate techniques.
4. Identify the respiratory defense mechanisms. 10. Distinguish normal from common abnormal findings in a
5. Discuss the significance of arterial blood gas values in physical assessment of a patient’s respiratory system.
relation to respiratory function. 11. Describe the purpose, significance of results, and nursing
6. Relate the signs and symptoms of inadequate oxygenation responsibilities related to diagnostic studies of the
to physical assessment findings. respiratory system.
7. Link age-related changes of the respiratory system to key
differences in assessment findings.
KEY TERMS
adventitious breath sounds oximetry
chemoreceptor oxygenation
compliance resistance
crackles, Table 27.6 surfactant
dyspnea tidal volume (Vt)
fremitus ventilation
mechanical receptors wheezes, Table 27.6
The primary purpose of the respiratory system is gas exchange. Upper Respiratory Tract
This involves the transfer of oxygen (O2) and carbon dioxide The upper respiratory tract includes the nose, mouth, pharynx,
(CO2) between the atmosphere and blood. While adequate perfu- epiglottis, larynx, and trachea. Air enters the respiratory tract
sion is needed to distribute O2 to the body tissues, adequate oxy- through the nose. The nose is made of bone and cartilage. It
genation depends on a healthy, functioning respiratory system. is divided into 2 nares by the nasal septum. The inside of the
nose is shaped into 3 passages by projections called turbinates.
STRUCTURES AND FUNCTIONS OF The turbinates increase the surface area of the nasal mucosa that
warms and moistens the air as it enters the nose. The internal
RESPIRATORY SYSTEM nose opens directly into the sinuses. The nasal cavity connects
The respiratory system is divided into 2 parts: the upper respira- with the pharynx. It is a tubular passageway that is subdivided
tory tract and the lower respiratory tract (Fig. 27.1). into 3 parts: nasopharynx, oropharynx, and laryngopharynx.
515
,516 SECTION 6 Problems of Oxygenation: Ventilation
Right Thyroid cartilage
Pharynx midclavicular Larynx
Nasal cavity line
Epiglottis Trachea
Larynx
Right Suprasternal notch
Trachea
mainstem Carina First rib
bronchus
Angle of
Segmental bronchi Right
Louis
upper
lobe Left
upper
Right lobe
middle
lobe
Right
Dust particle lower
Mucus lobe Left lower
Terminal Cilia lobe
bronchiole
Respiratory
bronchiole
Right anterior Midsternal
A axillary line line
Alveolar Vertebral line
duct
Goblet cell Spinal
B processes Right upper
Alveoli
lobe
Left
upper
lobe
Septa Pores of
Kohn
A
Left
Fig. 27.1 Structures of the respiratory tract. (A) Pulmonary functional lower Right
unit. (B) Ciliated mucous membrane. (Redrawn from Price SA, Wilson lobe lower
LM: Pathophysiology: clinical concepts of disease processes, ed 6, St lobe
Louis, 2003, Mosby.)
The nose protects the lower airway by warming and humidi-
fying air and filtering small particles before air enters the lungs.
The olfactory nerve, found within the mucosa of the upper part
of the nasal cavity, is responsible for the sense of smell.1
Air moves through the oropharynx to the laryngopharynx. It
then travels through the epiglottis to the larynx before moving B Scapular line
into the trachea. The epiglottis is a small flap behind the tongue Fig. 27.2 Landmarks and structures of the chest wall. (A) Anterior
that closes over the larynx during swallowing. This prevents sol- view. (B) Posterior view. (Redrawn from Thompson JM, McFarland GK,
ids and liquids from entering the lungs. The vocal cords are in Hirsch JE, et al: Mosby’s clinical nursing, ed 5, St Louis, 2002, Mosby.)
the larynx. Air passes through the glottis (the opening between
the vocal cords) and into the trachea. alveolar ducts, and alveoli. Except for the right and left main-
The trachea is a cylindrical tube about 5 inches (10 to 12 cm) stem bronchi, all lower airway structures are found within the
long and 1 inch (1.5 to 2.5 cm) in diameter. U-Shaped cartilages lungs. The right lung is divided into 3 lobes (upper, middle,
keep the trachea open but allow the adjacent esophagus to expand and lower) and the left lung into 2 lobes (upper and lower)
for swallowing. The trachea divides into the right and left main- (Fig. 27.2).
stem bronchi at a point called the carina. The carina is located at The mainstem bronchi, pulmonary vessels, and nerves enter
the angle of Louis, which is at the level of the 4th and 5th thoracic the lungs through a slit called the hilus. The right mainstem
vertebrae.2 The carina is highly sensitive. Stimulation of this area bronchus is shorter, wider, and straighter than the left mainstem
during suctioning causes vigorous coughing. bronchus. That is why aspiration is more likely to occur in the
right lung than in the left lung.
Lower Respiratory Tract The mainstem bronchi subdivide several times to form the
Once air passes the carina, it is in the lower respiratory tract. lobar, segmental, and subsegmental bronchi. Further divi-
The lower respiratory tract consists of the bronchi, bronchioles, sions form the bronchioles. The most distant bronchioles are
, CHAPTER 27 Assessment: Respiratory System 517
Conducting airways Respiratory unit Exhaled
PaO2 127 mm Hg
Bronchi, Sub- Bronchioles Alveolar PaCO2 28 mm Hg
Inhaled
Trachea segmental segmental ducts,
Non- Respiratory PaO2 159 mm Hg
bronchi bronchi respiratory alveoli
PaCO2 0.3 mm Hg
Alveolus
PaO2 100 mm Hg
PaCO2 40 mm Hg
Venous blood Arterial blood
PaO2 40 mm Hg PaO2 100 mm Hg
PaCO2 46 mm Hg PaCO2 40 mm Hg
Branchings 8 15 21-22 24 28
Fig. 27.3 Structures of lower airways. (Redrawn from Thompson JM, Fig. 27.4 Partial pressure of respiratory gases in normal respiration. The
McFarland GK, Hirsch JE, et al.: Mosby’s clinical nursing, ed 5, St Louis, pressures are shown in inhaled and exhaled air from the lungs and at
2002, Mosby.) the level of the alveoli and pulmonary venous and arterial blood vessels.
the respiratory bronchioles. The bronchioles are encircled by postoperative patient is at risk for atelectasis because of the
smooth muscles that constrict and dilate in response to various effects of anesthesia, decreased mobility, and pain, which
stimuli. The terms bronchoconstriction and bronchodilation refer can alter breathing and lung expansion. In acute respiratory
to a decrease or increase in the diameter of the airways caused distress syndrome (ARDS), lack of surfactant contributes
by contraction or relaxation of these muscles. Beyond the bron- to widespread atelectasis and collapse of lung tissue (see
chioles lie the alveolar ducts and alveoli (Fig. 27.3). Chapter 32).
The trachea and bronchi act as a pathway to conduct gases
to and from the alveoli. The volume of air in the trachea and Blood Supply
bronchi is called the anatomic dead space (Vd).3 This air does The lungs have 2 different types of circulation: pulmonary and
not take part in gas exchange. In adults, a normal tidal volume bronchial. Pulmonary circulation provides the lungs with blood
(VT), or volume of air exchanged with each breath, is about 500 that takes part in gas exchange. The pulmonary artery receives
mL (in a 150-lb man). Of each 500 mL inhaled, about 150 mL deoxygenated blood from the right ventricle of the heart and
is Vd. delivers it to pulmonary capillaries that lie directly alongside
The alveoli are the final part of the respiratory tract (Fig. the alveoli. O2–CO2 exchange occurs at this point. The pulmo-
27.3). Alveoli are small sacs in the lungs that are the primary nary veins return oxygenated blood to the left atrium, which
site of gas exchange for O2 and CO2. The adult lung has over then delivers it to the left ventricle, and into systemic circula-
300 million alveoli, each 0.3 mm in diameter. The alveoli are tion. Venous blood is collected from capillary networks of the
interconnected by pores of Kohn.4 They allow movement of air body and returned to the right atrium by way of the superior
from alveolus to alveolus (Fig. 27.1). Deep breathing promotes and inferior vena cava.
air movement through these pores and helps move mucus out Bronchial circulation starts with the bronchial arteries, which
of the respiratory bronchioles. Bacteria can also move through arise from the thoracic aorta. Bronchial circulation does not
these pores, spreading infection to previously uninfected areas. take part in gas exchange but provides O2 to the bronchi and
Alveoli have a total volume of about 2500 mL, with a surface other lung tissues. Deoxygenated blood returns from the bron-
area for gas exchange that is about the size of a tennis court. chial circulation through the azygos vein into the superior vena
Gases are exchanged across the alveolar-capillary membrane, cava.1
where the alveoli come in contact with pulmonary capillaries
(Fig. 27.4). In conditions such as pulmonary edema, excess fluid Chest Wall
fills the interstitial space and alveoli. This reduces gas exchange. The chest wall is shaped, supported, and protected by 24 ribs
(12 on each side). The thoracic cage, which consists of the ribs
Surfactant and sternum, protect the lungs and the heart from injury. The
Because alveoli are unstable, they have a natural tendency to mediastinum is the space in the middle of the thoracic cavity.
collapse. Alveolar cells secrete surfactant. Surfactant is a lipo- It contains the major organs of the chest, including the heart,
protein that lowers the surface tension in the alveoli.5 It reduces aorta, and esophagus. The mediastinum physically separates the
the amount of pressure needed to inflate the alveoli and makes right and left lungs into 2 separate compartments.
them less likely to collapse. Normally, each person takes a slightly The chest cavity is lined with a membrane called the pari-
larger breath, termed a sigh, after every 5 or 6 breaths. This sigh etal pleura. The lungs are lined with a membrane called the vis-
stretches the alveoli and promotes surfactant secretion. ceral pleura. The parietal and visceral pleurae join to form one
When there is not enough surfactant, the alveoli collapse. continuous membrane. The visceral pleura does not have any
The term atelectasis refers to collapsed, airless alveoli. The sensory (pain) fibers or nerve endings. The parietal pleura has
