CHAPTER 12 DISORDERS OF THE RESPIRATORY SYSTEM
PRETEST QUESTIONS
1. Pursed-lip breathing would be most beneficial in which of the following lung disorders?
2. On assessing a patient’s laboratory results, you notice a sputum culture that reveals a high eosinophil count. This is characteristic of which of the following pulmonary conditions?
3. Which lung condition is characterized by consolidation on chest films?
4. A 17-year-old asthmatic girl enters the emergency department in moderate respiratory distress. She states that the attack began about 1 h before she came to the emergency department. You would expect her ABG results to reveal
5. Which of the following causative organisms for pneumonia is characteristically seen in patients with acquired immunodeficiency syndrome (AIDS)?
6. The drug streptokinase is used to treat which of the following lung disorders?
REVIEW
I. Chronic Obstructive Pulmonary Disease (COPD)
COPD is a condition in which there is a chronic obstruction to airflow within the lungs. The following diseases discussed in the outline are classified as COPD: emphysema, chronic bronchitis, and asthmatic bronchitis. Typical asthma, cystic fibrosis, and bronchiectasis were considered to be COPD in the past but are no longer classified as such.1. Definition: a permanent abnormal enlargement of the air spaces distal to the terminal bronchioles, associated with destructive changes of the alveolar walls
(1) The acinus is the anatomic gas exchange unit of the lung, made up of the respiratory bronchiole, alveolar duct, alveolar sacs, and the alveoli.
(1) Lesion is in the center of the lobules, which results in enlargement and destruction of the respiratory bronchioles.
e. Emphysema diminishes the area over which gas exchange occurs and is accompanied by regional differences in ventilation and perfusion. This accounts for increased physiologic dead space and the abnormal ABG results observed in patients with emphysema.
(1) Cor pulmonale results from an increased workload on the right ventricle as it attempts to deliver blood through constricted pulmonary blood vessels.
(2) These vessels are constricted (causing pulmonary hypertension) as a result of arterial hypoxemia and hypercarbia.
(3) Chronic pulmonary hypertension results in right ventricular hypertrophy and, eventually, right-sided heart failure.
(4) Cor pulmonale results in peripheral edema, such as pedal (ankle) edema, distended neck (jugular) veins, and an enlarged liver.
(2) Nicotine replacement therapy: nicotine gum, nicotine patch, nicotine inhaler, nicotine lozenge, nicotine nasal spray
(3) Drug therapy: bupropion (Wellbutrin); an antidepressant drug that has proved to be beneficial in smoking cessation
(4) Frequent reminders from health care providers about the need to stop smoking to improve quality of life
(5) Discussions with a respiratory therapist or other health care provider to help the patient understand the effects that smoking has on the cardiopulmonary system
(2) Pursed-lip breathing: prevents premature airway closure by producing a back pressure into the airways on exhalation.
h. Care must be taken when administering oxygen to patients with emphysema who chronically retain CO2 and who have chronic hypoxemia. PaO2 levels should be maintained between 50 and 65 mm Hg to avoid blunting the respiratory drive or increasing V/Q mismatching.
Exam Note1. Definition: chronic excessive mucus production, resulting from an increase in the number and size of mucus glands and goblet cells. Symptoms are a cough and increased mucus production for at least 3 months of the year for more than 2 consecutive years. Males are most commonly affected.
A. Definition: a disease characterized by increased reactivity of the trachea and bronchi to various stimuli, resulting in bronchoconstriction (bronchospasm), increased mucus production, and swelling of mucosal tissue
c. The patients in this category generally have FEV1 and peak expiratory flow (PEF) values of at least 80% of predicted.
a. Symptoms of coughing or wheezing are experienced more than twice per week but less than once per day.
b. Symptoms affect the patient’s daily activity and sleep during the night; nocturnal coughing, wheezing, or dyspnea is experienced more than twice per month.
d. Routine management generally consists of a corticosteroid to control symptoms and the use of a beta agonist, as needed.
e. Emergency department treatment for exacerbations occurs periodically and may occasionally result in hospitalization.
b. Exacerbation of symptoms are experienced at least twice per week and may persist for several days.
c. Symptoms affect the patient’s daily activity and sleep during the night; nocturnal coughing, wheezing, or dyspnea is experienced more than once per week.
e. Daily management generally consists of a long-acting, aerosolized bronchodilator to control nocturnal symptoms, corticosteroids two or three times per day, and a short-acting beta agonist as needed for exacerbations.
f. Patients in this category routinely require emergency department treatment or require hospitalization.
a. This is the worst category of the four. Symptoms of coughing or wheezing are experienced almost continually.
c. Symptoms affect the patient’s daily activity and sleep during the night; nocturnal coughing, wheezing, or dyspnea is experienced almost every night.
e. Daily management generally consists of a long-acting, aerosolized bronchodilator to control nocturnal symptoms, corticosteroids, and a short-acting beta agonist two to three times per day.
f. Patients in this category routinely require emergency department treatment or require hospitalization.
1. Mild wheezing and coughing initially, which may progress to severe dyspnea if the attack is not arrested
2. The cough is initially nonproductive, progressing to a productive cough by the end of the episode.
8. ABG levels initially reveal hypoxemia and low PaCO2. PaCO2 increases as the attack worsens and the patient begins to tire.
2. Medications (long-term controllers taken daily to help control or maintain the degree of inflammatory mediator release in the airways)
1. Quick-relief, short-acting beta agonists such as albuterol (Ventolin, Proventil) or anticholinergic bronchodilators such as ipratropium bromide (Atrovent)
J. Status Asthmaticus: a severe asthmatic attack that responds poorly to bronchodilator therapy and is associated with signs or symptoms of potential respiratory failure
8. If the attack is not controlled by previous measures, intubate the patient and institute mechanical ventilation.
1. Nocturnal (nighttime) symptoms are seen in up to 75% of all patients with asthma and even in those who have mild intermittent or mild persistent asthma.
2. Mechanisms resulting in nocturnal symptoms may be related to changes in vagal tone, body temperature, mediators, epinephrine, inflammation, and beta2–receptor function during sleep.
3. Other causes may include aspiration, sleep apnea, increased mucus production, sinusitis, gastroesophageal reflux, and the normal decrease in lung function when the patient is sleeping.
4. Management generally includes sustained-release theophylline and beta agonists, long-acting beta agonists, and/or inhaled corticosteroids.
1. Characterized by increased wheezing or coughing while at work or within several hours after leaving work and improving on days off from work.
3. The most common workplace causes include formaldehyde, grain dust, cigarette smoke, and avian proteins.
1. Characterized by symptoms occurring 5 to 15 min after strenuous exercise that spontaneously resolves in about 1 h.
c. Rapid rewarming of the airway, resulting in vascular congestion, increased permeability, and edema causing airway obstruction
3. Beta agonists may be used beneficially before exercise along with asthma preventives such as cromolyn sodium or nedocromil sodium (Tilade) or the leukotriene modifiers such as zafirlukast or montelukast.
4. Other medications that can be beneficial include anticholinergics such as ipratropium bromide, oral beta agonists, theophylline, and antihistamines.
5. Some nonasthma medications such as inhaled furosemide (Lasix) and inhaled heparin have also been used to treat EIA.
A. Definition: a dilation of the bronchi and bronchioles that is chronic in nature and results in inflammation and damage to the walls of these airways.
1. It is not clear whether the chronic dilation is a result of destructive changes in the bronchial walls caused by inflammation and infection or, possibly, a congenital defect of the airways.
2. Bronchial obstruction may render the mucociliary transport system ineffective, which may lead to an accumulation of thick secretions.
4. Because of the decreased values in both flows and volumes, this disease may be either obstructive or restrictive in nature (see characteristics on pulmonary function studies).
1. Productive cough with large amounts of thick, purulent secretions that may be foul-smelling. Often, a layering of the sputum occurs.
IV. LOWER RESPIRATORY TRACT INFECTIONS
a. Pathogenic microorganisms that reach the gas exchange areas of the lung cause an intense tissue reaction, resulting in production of inflammatory exudates and cells.
e. If tissue necrosis occurs, healing is slow and fibrous scar tissue is produced, which results in pulmonary fibrosis and loss of normal lung function.
(1) Causative organism is Streptococcus pneumoniae: called pneumococcal pneumonia; most common bacterial pneumonia
(2) This type of pneumonia is seen in 60% of AIDS cases. Definitive diagnosis is made from cultures of lung secretions and tissue.
(3) P. carinii pneumonia is commonly treated with the antiprotozoal drug pentamidine via aerosolization.
Bronchoalveolar lavage (BAL) is a technique whereby sterile saline is instilled through a bronchoscope to a specific lung segment. The saline is then aspirated and collected for culturing. BAL is being used to help diagnose nosocomial pneumonia. Recently, it is being advocated for diagnosing ventilator-associated pneumonia (VAP). VAP is discussed in detail in Chapter 11 on ventilator management.
f. Tracheal suctioning (if there has been poor removal of secretions because of ineffective coughing)
1. Definition: an infection of the lung that is characterized by a localized accumulation of pus and destruction of the surrounding tissue.
b. Aerobic bacteria, including staphylococci, streptococci, and some gram-negative bacteria, may be less common causes.
b. Cough, initially nonproductive (or minimal production), followed by production of purulent, foul-smelling secretions.
b. Most common sites are the superior segments of the lower lobes and posterior segments of upper lobes (as a result of position during an aspiration event).
Exam Note1. Definition: a granulomatous bacterial infection, chronic in nature, affecting the lungs and other organs of the body.
2. Cause: The inhalation or ingestion of the bacterium, Mycobacterium tuberculosis. Infection is usually spread through coughing and sneezing. Diagnosis is based on skin tests, chest films, and sputum culture showing bacilli that are acid-fast, which means not readily decolorized by acid after staining, a specific characteristic of this bacteria.
a. After the bacillus is inhaled, it enters the alveoli, which results in an inflammatory reaction similar to that seen in pneumonia.
c. The lung tissue surrounding this area encapsulates the bacilli, providing a protective covering. This is called a granuloma, or tubercle.
d. The granuloma fills with necrotic material and is referred to as a caseous (cheese-like) granuloma.
e. If the patient’s immunologic system controls this process or if antituberculosis drugs are given, the lung tissue becomes fibrotic and calcifies as healing occurs. This may result in stiffness or decreased lung compliance in the affected area.
f. In most cases, the patient’s own immunologic mechanisms keep the bacilli in check, but the bacillus remains dormant in the lungs for many years, which causes a positive result on TB skin tests. These encapsulated bacilli can escape in later years, causing infection.
h. In uncontrolled cases, the tubercles increase in size and combine to form larger tubercles, which may rupture and permit air and the infected material to enter the pleural space, bronchi, and bronchioles.
Most individuals infected with TB have few, if any, symptoms. The primary TB lesion heals completely, possibly leaving a small scar, which could calcify later in life.
Exam Note1. Definition: an excessive amount of fluid in the lung tissues or alveoli, caused by an increase in pulmonary capillary pressure resulting from hydrostatic left-sided abnormal heart function
These four mechanisms cause back up of fluid from the heart into the pulmonary capillaries until they become engorged, which leads to pulmonary edema; PCWP and PAP levels are also increased.e. Alveolar capillary membrane leakage caused by injury, such as seen in ARDS (noncardiogenic pulmonary edema). The PCWP level is normal with an increased PAP in this instance.
b. Oncotic pressure is normally much higher than capillary hydrostatic pressure, keeping fluid in the capillaries.
c. As blood from the heart backs up into the pulmonary circulation, capillary hydrostatic pressure increases above plasma oncotic pressure, and fluid from the blood leaks out into the interstitial spaces.
d. Excess fluid overwhelms the lymphatic system (which normally drains the interstitial spaces), and the fluid drains into the alveoli, which results in decreased lung compliance.
(1) Orthopnea: dyspnea while lying down (relieved by sitting upright in semi-Fowler or Fowler position)
(2) Paroxysmal nocturnal dyspnea: severe attack of dyspnea that occurs during sleep and awakens the patient (relieved by sitting up in semi-Fowler position)
g. IPPB with ethyl alcohol (40% to 50% dilution). Not used commonly in the clinical setting but may appear on the exam.
a. The blood clot usually originates in deep veins of the legs or pelvic area, dislodges, travels back to the heart through the venous system, and lodges in the pulmonary artery.
b. The clot originally forms because of stagnation or venous stasis from prolonged bed rest, immobility from the pain of trauma or surgery, or paralysis.
c. Seen in patients with COPD because of venous stasis, resulting from the increased viscosity of their blood.
a. Blood flow is obstructed to areas of the involved lung, which contributes to dead space ventilation (ventilation without perfusion).
b. Lung compliance decreases as atelectasis occurs in the region of the decreased perfusion. This is the lung’s response to inadequate perfusion as it attempts to maintain normal V/Q matching.
6. Diagnostic procedures. A valuable procedure for the diagnosis of PE is a V/Q lung scan. Normal results on a perfusion scan should rule out PE. Pulmonary angiography is another procedure that is sometimes performed for definitive diagnosis of PE.
a. V/Q scan: The patient inhales a harmless radioactive substance, which is distributed throughout the alveoli. A small amount of radioactive imaging material is injected into a vein, and it too travels to the lung and outlines the blood supply or perfusion to the lung. Areas with inadequate perfusion appear dark on the scan because the radioactive particles are unable to pass to an area of obstruction.
b. Pulmonary angiography is the most accurate method for detecting PE. A dye that is visible on x-ray film is injected into an artery and travels to the pulmonary arteries, where the obstruction is outlined and can be viewed.
c. MRI and CT are also used to detect PE (see Chapter 3 on assessment of the cardiopulmonary patient); however, pulmonary angiography, although associated with more risks, is currently the most diagnostic test for PE.
1. Definition: a group of symptoms causing acute, catastrophic respiratory failure, resulting from pulmonary injury. For the lung condition to be considered ARDS, three criteria must be met
d. Surfactant production decreases, which results in atelectasis, while excessive fluid fills the alveoli and airways.
e. Because of inflammatory cells, fibrin, and cellular debris that result from the inflammatory process, the lungs become stiff and lung compliance decreases.
f. In severe cases, the lungs may become almost entirely atelectatic, which may lead to massive intrapulmonary shunting.
a. Patients are usually not managed well on high O2 concentrations alone because of decreased lung compliance.
(1) Because the lungs are noncompliant, higher peak inspiratory pressures are necessary to maintain normal PaCO2 levels. High peak pressures result in the release of inflammatory chemical mediators, causing more lung damage. To prevent further lung tissue damage, do not use a peak inspiratory pressure in excess of 35 to 40 cm H2O and maintain alveolar pressure (static pressure) at less than 30 cm H2O. Protecting the lungs by using lower ventilating pressures causes the PaCO2 level to rise. This is referred to as permissive hypercapnia, which results in a decreased pH level. If the pH level does not decrease to less than 7.20, no significant side effects have been noted. (In some studies, pH levels as low as 7.10 have been found to be safe.) The elevated PaCO2 has three advantages
(2) Add PEEP if PaO2 is below normal when the patient is receiving an FiO2 of 0.60 or more. The optimal level of PEEP can be determined by observing the lower inflection point on a volume/pressure curve. (See Chapter 11 on ventilator management.)
a. When air enters the pleural space, the negative pressure in the pleural space becomes atmospheric, which causes the “negative” pull on the lung to be lost. The lung begins to collapse because of its natural recoil properties, diminishing ventilation to the lung.
b. A tension pneumothorax occurs when the opening to the pleural space in the lung acts as a one-way valve, permitting air to enter the space but not allowing the air to exit.
(2) The trapped air increases pressure on the affected side, pushing the trachea and mediastinum to the unaffected side. Pressure compresses the heart, which results in a decreased cardiac output. This is a life-threatening condition.
(3) The immediate action to take is to relieve the pressure in the pleural space by insertion of a needle in the second or third intercostal space.
c. The volume of the unaffected lung will increase and more blood will perfuse it, which helps prevent severe hypoxemia.
f. Crepitus with subcutaneous emphysema (crepitus refers to the crackling under the skin that is felt when air enters the subcutaneous tissues)
b. Deviation of heart, trachea, and mediastinum to the opposite (unaffected) side if tension pneumothorax is present
a. Although chest x-ray films enable a definitive diagnosis of pneumothorax in patients of all ages, transillumination with a fiberoptic probe has been successful in the diagnosis of pneumothorax in infants. The transilluminator has a light on its distal tip, and when it is placed over areas of free air in the pleural space, transillumination is greater than in other areas.
a. Transudate: fluid caused by an imbalance between transcapillary pressure and plasma oncotic pressure
a. Fluid accumulates in the pleural space as a result of an imbalance between the formation of the fluid and how much is absorbed.
Exam Note1. Definition: partial or complete collapse of alveoli. It may involve small localized areas of the lung, a lobe, or the entire lung.
a. Obstructed airways: This may result from secretions, tumors, mucous plugs, or foreign body aspiration. These obstructions to gas flow prevent air from reaching the alveoli for gas exchange. This is referred to as absorption atelectasis. Another example of absorption atelectasis occurs when high levels of O2 are delivered to the lung. This “washes out” the nitrogen in the lung, which results in collapsed alveoli.
b. Loss of negative pleural pressure: There is subatmospheric pressure present in the pleural space, which creates a pull on the lung that helps to keep it from collapsing. Any condition that results in loss of this subatmospheric (negative) pressure causes the lung to collapse. Pneumothorax and pleural effusion are both causes of the loss of negative intrapleural pressure.
c. Right mainstem bronchus intubation: If the right mainstem bronchus is inadvertently intubated, no gas flow enters the left lung, which results in atelectasis of the left lung. The same holds true for a left mainstem bronchus intubation, but the incidence is much less common because the angle of the left mainstem bronchus is 45 degrees to 55 degrees; the right mainstem bronchus angles off the trachea at about 25 degrees, which makes right bronchus intubation more likely.
d. Deficiency or loss of surfactant: Surfactant is present in the fluid that lines the alveolar wall and reduces surface tension so that alveoli do not collapse during exhalation. Conditions resulting in reduced surfactant include O2 toxicity, in which high O2 levels damage the alveolar type II cells that produce surfactant, which leads to ARDS; near-drowning, which results in loss of surfactant from the aspiration of certain substances; and premature birth, in which surfactant is immature, resulting in atelectasis (see Chapter 13 on neonatal and pediatric respiratory care).
e. Hypoventilation: Decreased VT from any condition eventually results in atelectasis. Examples include chest or abdominal pain, phrenic nerve paralysis, abdominal or thoracic surgery, high-level spinal cord injury, inadequate ventilator VT settings, and unconsciousness.
f. Decreased pulmonary blood flow: If a PE is blocking blood flow to the alveoli, the lungs compensate by reducing volume to the specific alveoli (resulting in atelectasis) in which there is deficient perfusion; thus, blood will more likely perfuse open alveoli.
a. As a result of the conditions resulting in atelectasis mentioned in the previous section, FRC and VC decrease.
b. Intrapulmonary shunting occurs as capillary blood passes by collapsed alveoli, preventing normal gas exchange from taking place and resulting in hypoxemia.
c. Treatment of underlying atelectasis with deep-breathing exercises, such as incentive spirometry or IPPB
CRT Exam Content Matrix: IB9o,t, IB10o,t, IC11
RRT Exam Content Matrix: IA10, IB9p,u, IB10q,v, IC13, IIIK8
A. Sleep apnea is present in patients who have at least 30 episodes of apnea over a 6-h period of sleep.
b. During the apneic period, the patient exhibits strong and often intense respiratory effort. (See waveform pattern below.)
c. Although sleep posture (sleeping on the side rather than supine) has some benefits, the use of CPAP or Bi-PAP while sleeping is the most effective method for treating obstructive sleep apnea.
a. Apnea occurs because of the failure of the central respiratory centers (in the medulla) to send signals to the respiratory muscles.
b. It is characterized by the absence of inspiratory effort with no diaphragmatic movement (unlike obstructive sleep apnea).
Some patients may have a combination of both obstructive and central sleep apnea, which is defined as mixed sleep apnea.1. Sleep studies are a very effective method for the diagnosis of sleep apnea and other breathing disorders such as sudden infant death syndrome (SIDS).
2. Sleep studies are also valuable in determining the cause, severity, and pathophysiologic effects of the breathing disorder during sleep.
d. Absence of airflow (apnea) is determined with the use of a CO2 analyzer, thermistor, tracheal sound recorder, or a pneumotachograph
PES represents esophageal pressure measurements in the diagrams.g. Waveform “12-1” is an example of obstructive sleep apnea. Notice there are periods of no airflow with an increase in intensity of chest movement. This indicates that the upper airway is obstructed and the patient struggling to breathe.
h. Waveform “12-2” indicates central sleep apnea. Note that there is neither airflow nor chest excursion.
POSTCHAPTER STUDY QUESTIONS
1. List three lung disorders classified as COPD.
2. List the common findings on the chest films of a patient with emphysema.
3. What PaO2 level should be maintained for a COPD patient with chronic hypoxemia?
4. List the clinical signs and symptoms of cor pulmonale.
5. How does O2 therapy help prevent or treat cor pulmonale?
6. The count of which type of WBC is characteristically elevated in the sputum and blood of a patient with asthma?
7. What aerosolized medication is used to treat P. carinii pneumonia?
8. List four causes of cardiogenic pulmonary edema.
9. List the signs and symptoms of pulmonary edema.
10. List the treatment modalities for pulmonary edema.
11. List the various causes of ARDS.
12. List the signs and symptoms of ARDS.
13. List treatment modalities for ARDS.
15. What is the immediate treatment for a tension pneumothorax?
16. What is the most effective method for treating obstructive sleep apnea?
17. List six variables that are measured during a sleep study.
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