will be seen in about 50% of pulmonary embolism/infarction cases, and an elevated hemidiaphragm occurs in as many as
40% of cases.
Computed Tomography Pulmonary Angiogram
The spiral (helical) volumetric computed tomography pulmonary angiogram (CTPA) (also called CT pulmonary angiography) with intravenous contrast is fast becoming the first-line test for diagnosing suspected pulmonary embolism. The CTPA is increasingly being preferred to the previous gold standards for diagnosing a pulmonary embolism— ventilation-perfusion (V/Q) scanning or direct pulmonary angiography—because (1) the scan requires only an intravenous line, (2) the image resolution is very good, (3) the volumetric scanning allows the contrast material to be administered more economically and timed more precisely, and (4) the entire chest can be scanned in a single breath hold, or in several successive short breath holds. (See CTPA scan in Radiologic Findings, page 311.)
Ventilation-Perfusion Scan
The V/Q scan is rarely used today to identify a pulmonary embolus. A V/Q scan is reliable only at the extremes of interpretation (i.e., the test confirms that the lungs are normal or that there is a high probability of a pulmonary embolism). The V/Q scan often raises more questions than it answers. This test is quickly being replaced by more sensitive and rapid tests, such as spiral CTPA scans (see earlier discussion).
Pulmonary Angiogram
A pulmonary angiogram provides a clear image of the blood flow in the lung's arteries. It is an extremely accurate test for diagnosis of pulmonary embolism. However, because it is invasive (catheter insertion and dye injection), is timeconsuming (about 1 hour), and requires a high degree of skill to administer, it is usually performed only when other tests have failed to provide a definitive diagnosis. More contrast dye is used in this study than in the pulmonary embolism CTPA scan (see Pulmonary Angiogram in Radiologic Findings, page 311).
Magnetic Resonance Imaging
A magnetic resonance imaging (MRI) scan of the chest may be used for individuals whose kidneys may be harmed by dyes used in x-ray tests and for women who are pregnant.
Magnetic Resonance Angiography
Magnetic resonance angiography (MRA) may be used to differentiate among blood (usual), thromboemboli, and tumor emboli in patients with malignancy.
Overview of the Cardiopulmonary Clinical Manifestations Associated With Pulmonary Embolism1
The following clinical manifestations result from the pathologic mechanisms caused (or activated) by atelectasis (see Fig. 10.7)—the major anatomic alteration of the lungs associated with a pulmonary infarction (see Fig. 21.1). Bronchospasm (see Fig. 10.10) also may explain some of the following findings. It occurs rarely and is of little clinical significance compared with the atelectasis caused by pulmonary infarction and hypoxemia resulting from the increased physiologic dead space.
Clinical Data Obtained at the Patient's Bedside
The Physical Examination
Vital Signs
Increased Respiratory Rate (Tachypnea)
Several unique mechanisms probably work simultaneously to increase the rate of breathing in patients with pulmonary embolism.
Increased Physiologic (Alveolar) Dead Space
Pulmonary embolic disease is the classic example of this type of pathophysiology. For example, when an embolus lodges in the pulmonary vascular system, blood flow is reduced or completely absent distal to the obstruction. Consequently, the alveolar ventilation beyond the obstruction is wasted, or dead space, ventilation, and no carbon dioxide–oxygen exchange occur. The ventilation-perfusion (V/Q) ratio distal to the pulmonary embolus is high and may even be infinite if there is no perfusion at all (Fig. 21.2).
FIGURE 21.2 Dead-space ventilation in pulmonary embolism.
Although portions of the lungs have a high V/Q ratio at the onset of a pulmonary embolism, this condition is quickly reversed and a decrease in the V/Q ratio occurs. The pathophysiologic mechanisms responsible for the decreased V/Q ratio are as follows. In some cases of pulmonary embolus, pulmonary infarction may develop and cause alveolar atelectasis, consolidation, and pulmonary parenchymal necrosis. In addition, the embolus is thought to activate the release of humoral agents such as serotonin, histamine, and prostaglandins into the pulmonary circulation, causing bronchial constriction. Collectively, the alveolar atelectasis, consolidation, tissue necrosis, and bronchial constriction lead to decreased alveolar ventilation relative to the alveolar perfusion (decreased V/Q ratio). As a result of the decreased V/Q ratio, pulmonary
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shunting and venous admixture ensue.
Stimulation of Peripheral Chemoreceptors Producing Hypoxemia
The result of the venous admixture is a decrease in the patient's PaO2 and CaO2 (Fig. 21.3). It should be emphasized that
it is not the pulmonary embolism but rather the decreased V/Q ratio that develops from the pulmonary infarction (atelectasis and consolidation) and bronchial constriction (release of cellular mediators) that actually causes the reduced PaO2. As this condition intensifies, the patient's oxygen level may decline to a point low enough to stimulate the peripheral
chemoreceptors, which in turn initiates an increased ventilatory rate.
FIGURE 21.3 Venous admixture may develop in pulmonary embolism as a result of bronchial smooth muscle constriction (shuntlike effect). Venous admixture also may occur when an embolus leads to pulmonary infarction and causes alveolar atelectasis and consolidation (true capillary shunt). Alveolar atelectasis and consolidation are not shown in this illustration.
Reflexes From the Aortic and Carotid Sinus Baroreceptors
If obstruction of the pulmonary vascular system is severe, left ventricular output will diminish and cause the systemic blood pressure to drop. The decreased systemic blood pressure reduces the tension of the walls of the aorta and carotid artery, which activates the baroreceptors. Activation of the baroreceptors in turn initiates an increased heart and ventilatory rate.
Other pathophysiologic mechanisms that may increase the patient's dyspnea and ventilatory rate include stimulation of the J receptors, anxiety, and pain.
Increased Heart Rate
The two major mechanisms responsible for the increased heart rate associated with pulmonary embolism are reflexes from the aortic and carotid sinus baroreceptors and stimulation of the pulmonary reflex mechanism.
For a discussion of reflexes from the aortic and carotid sinus baroreceptors, see the previous section on increased respiratory rate. The increased heart rate also may reflect an indirect response to hypoxic stimulation of the peripheral chemoreceptors, mainly the carotid bodies. When the carotid bodies are stimulated in this manner, the patient's ventilatory rate increases. As a result of the increased rate of lung inflation, the pulmonary reflex mechanism is activated; this mechanism triggers tachycardia.
Systemic Hypotension (Decreased Blood Pressure)
When significant pulmonary hypertension develops in pulmonary embolic disease, it is nearly always present because of the decrease in the cross-sectional area of the pulmonary vascular system, which reduces cardiac return and causes a decrease in left ventricular output and systemic hypotension. This is an ominous sign.
Cyanosis
Cough and Hemoptysis
As a result of the pulmonary hypertension, the pulmonary hydrostatic pressure, which is normally about 15 mm Hg, often becomes higher than the pulmonary oncotic pressure (normally about 25 mm Hg). This increase in the hydrostatic pressure permits plasma and red blood cells to move across the alveolar-capillary membrane and into alveolar spaces in a process similar to that seen in cardiogenic pulmonary edema. If this process continues, the subepithelial mechanoreceptors located in the bronchioles, bronchi, and trachea are stimulated. Such stimulation initiates a cough reflex and the expectoration of blood-tinged sputum.
Peripheral Edema and Venous Distention
•Distended neck veins
•Swollen and tender liver
•Ankle and feet swelling
•Pitting edema
Chest Pain and Decreased Chest Expansion
Chest pain is frequently noted in patients with pulmonary embolism. The origin of the pain is obscure. It may be cardiac
or pleuritic, but it is one of the common early findings in all forms of pulmonary embolism, even in the absence of clinically obvious cor pulmonale or pleural involvement. If the patient has systemic hypotension, perfusion of the coronary arteries decreases and classic angina-like chest pain (and electrocardiographic [ECG] findings) may result.
Syncope, Lightheadedness, and Confusion
If the left ventricular output and systemic blood pressure decrease substantially, blood flow to the brain may also diminish significantly. This may cause periods of lightheadedness, confusion, and even syncope.
Abnormal Heart Sounds
•Increased second heart sound (S2)
•Increased splitting of the second heart sound (S2)
•Third heart sound (or ventricular gallop) (S3)
Increased Second Heart Sound (S2)
As a result of pulmonary embolization, abnormally high blood pressure develops in the pulmonary artery. This condition causes the pulmonic valve to close more forcefully. As a result, the sound produced by the pulmonic valve (P2) is often
louder than the aortic sound (A2). This finding may be noted in the patient's chart as “P2 > A2,” which reflects that S2 is
louder when the area over the pulmonic valve in the second intercostal, left of the sternal notch, as compared with the intensity of sound to the right of the sternal notch. (The aortic second heart sound [A2], is normally widely heard over the
entire anterior left chest.)
Increased Splitting of the Second Heart Sound (S2)
Two major mechanisms either individually or together may contribute to the increased splitting of S2 sometimes noted in
pulmonary embolism: increased pulmonary hypertension and incomplete right bundle branch block.
The incomplete right bundle branch block (RBBB) that sometimes accompanies pulmonary embolism also may contribute to the increased splitting of S2. In incomplete heart block, the electrical activity through the right side of the heart is
delayed; this delayed activity in turn slows right ventricular contraction. The blood pressure in the pulmonic valve area remains higher than normal for a longer time during right ventricular contraction. As a result, the closure of the pulmonic valve is delayed, which may further widen the S2 split.
Splitting of the second heart sound is usually best heard in the second left intercostal space, close to the upper sternal border with a diaphragm of the stethoscope.
Third Heart Sound (S3, Ventricular Gallop)
A third heart sound (S3), or ventricular gallop, is sometimes heard in patients with pulmonary embolism. It occurs early in diastole, about 0.12 to 0.16 seconds after S2. Although its precise origin is unknown, S3 is thought to be created by
cardiac wall vibrations during diastole, when the rush of blood into the ventricles is abruptly stopped by ventricular walls that have lost some of their elasticity because of hypertrophy. An S3 generated in the right ventricle usually is best heard to
the right of the cardiac apex, close to the lower sternal border during inspiration.
Other Cardiac Manifestations
Right Ventricular Heave or Lift
As a consequence of the elevated pulmonary blood pressure, right ventricular strain or right ventricular hypertrophy (or both) often develops. When this occurs, a sustained outward lift of the chest wall can be felt at the lower left side of the sternum during systole (Fig. 21.4), because the right ventricle lies directly beneath the sternum.
FIGURE 21.4 A right ventricular lift can be detected in patients with a pulmonary embolism if significant pulmonary hypertension is present.
Chest Assessment Findings
•Crackles
•Wheezes
•Pleural friction rub (especially when pulmonary infarction involves the pleura)
Clinical Data Obtained From Laboratory Tests and Special Procedures
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Arterial Blood Gases
Mild to Moderate Stages
Acute Alveolar Hyperventilation With Hypoxemia2 (Acute Respiratory Alkalosis)
pH
PaCO2
PaO23
SaO2 or SpO23
↑
↓
↓ (but normal)
↓
↓
2See Fig. 5.2 and Table 5.4 and related discussion for the acute pH, PaCO2, and changes associated with acute alveolar hyperventilation.
Severe Stage
Acute Ventilatory Failure With Hypoxemia4 (Acute Respiratory Acidosis)
pH5
PaCO
2
5
PaO 3
SaO
2
or SpO 3
2
2
↓
↑
↑ (but normal)
↓↓
↓↓
3NOTE: A large saddle embolus can cause a sudden and dramatic drop in PaO2, SaO2, or SpO2 values.
4See Fig. 5.2 and Table 5.5 and related discussion for the acute pH, PaCO2, and changes associated with acute and chronic ventilatory failure.
5When tissue hypoxia is severe enough to produce lactic acid, the pH and values will be lower than expected for a particular PaCO2 level.
Oxygenation Indices6
QS/QT
DO27
VO2
O2ER
↑
↓
N
N
↑
↓
7The DO2 may be normal in patients who have compensated to the decreased oxygenation status with (1) an increased cardiac output, (2) an increased hemoglobin level, or (3) a combination of both. When the DO2 is normal, the O2ER is usually normal.
8CO, Cardiac output; CI, cardiac index; CVP, central venous pressure; LVSWI, left ventricular stroke work index; , mean pulmonary artery pressure; PCWP, pulmonary capillary wedge pressure; PVR, pulmonary vascular resistance; RAP, right atrial pressure; RVSWI, right ventricular stroke work index; SV, stroke volume; SVI, stroke volume index; SVR, systemic vascular resistance.
Normally the pulmonary artery pressure is no greater than 25/10 mm Hg, with a mean pulmonary artery pressure of about 15 mm Hg. Most patients with a pulmonary embolism, however, have a mean pulmonary artery pressure in excess of 20 mm Hg. Three major mechanisms may contribute to this: (1) decreased cross-sectional area of the pulmonary vascular system because of the embolism, (2) vasoconstriction induced by humoral agents, and (3) vasoconstriction induced by alveolar hypoxia.
Decreased Cross-Sectional Area of the Pulmonary Vascular System Because of the Embolus
The cross-sectional area of the pulmonary vascular system will decrease significantly if a large embolus becomes lodged in a major artery or if many small emboli become lodged in numerous small pulmonary vessels.
Vasoconstriction Induced by Humoral Agents
One of the consequences of pulmonary embolism is the release of certain humoral agents, primarily serotonin and prostaglandin. These agents induce smooth muscle constriction of both the tracheobronchial tree and the pulmonary vascular system. Such smooth muscle vasoconstriction may further reduce the total cross-sectional area of the pulmonary vascular system and cause the pulmonary artery pressure to rise further.
Vasoconstriction Induced by Alveolar Hypoxia
In response to the humoral agents liberated in pulmonary embolism, the smooth muscles of the tracheobronchial tree constrict and cause the V/Q ratio to decrease and the PaO2 to decline. Although the precise mechanism is unclear, when
the PaO2 and PaCO2 decrease, pulmonary vasoconstriction routinely ensues. This action appears to be a normal
compensatory mechanism that offsets the shunt produced by underventilated alveoli. When the number and/or extent of hypoxic areas becomes significant, however, generalized pulmonary vasoconstriction may develop and further contribute to the increase in pulmonary blood pressure. When the pulmonary embolism is severe, right-sided heart strain and cor pulmonale may ensue. Cor pulmonale leads to an increased central venous pressure, distended neck veins, and a swollen and tender liver.
Abnormal Electrocardiographic Patterns
•Sinus tachycardia
•Atrial arrhythmias
•Trial tachycardia
•Atrial flutter
•Atrial fibrillation
•Acute right ventricular strain pattern and right bundle branch block
•P pulmonale (peaked P waves)
In some cases, the obstruction of pulmonary blood flow produced by pulmonary emboli leads to abnormal ECG patterns. However, there is no single ECG pattern diagnostic of pulmonary embolism. Abnormal patterns merely suggest the possibility of pulmonary embolic disease. Sinus tachycardia is the most common arrhythmia seen. The sinus tachycardia and atrial arrhythmias sometimes noted are also thought to be related to the increased right-sided heart strain and cor pulmonale. In about 15% to 25% of patients with a pulmonary embolism, an S1Q3T3 pattern may be seen, which is a large S
wave in lead I, plus a large Q wave and an inverted T wave in lead III.
Radiologic Findings
Chest Radiograph
•Increased density (in infarcted areas)
•Hyperradiolucency distal to the embolus (in noninfarcted areas)
•Dilation of the pulmonary arteries
•Pulmonary edema
•Right ventricular cardiomegaly (cor pulmonale)
•Pleural effusion (usually small)
Patients with a pulmonary embolus often demonstrate no radiographic signs. However, a density with an appearance similar to that of pneumonia may be seen if infarction has occurred. Hyperradiolucency also may be apparent distal to the embolus; it is caused by decreased vascularity (Westermark sign). Dilation of the pulmonary artery on the affected side, pulmonary edema (common after a fat embolus), right ventricular cardiomegaly, and pleural effusions also may be seen.
Computed Tomography Pulmonary Angiogram
The computed tomography pulmonary angiogram (CTPA) scan is fast becoming the first-line diagnostic imaging tool to confirm a pulmonary embolism. As shown in Fig. 21.5, a relatively dark area—the thrombus—is clearly outlined by the brighter contrast (blood flow).
FIGURE 21.5 Oblique coronal projections from a computed tomography pulmonary angiogram (CTPA). Intravenous contrast material is very bright in the visible portions of the superior vena cava and in the superior portion of the right atrium because the contrast material was injected into an antecubital vein. The contrast material mixes in the right atrium with darker blood (without contrast) from the inferior vena cava, resulting in moderate brightness in that chamber, the right ventricle, and the pulmonary artery. The relatively dark area (thrombus) in the right pulmonary artery is clearly outlined by the brighter area (blood flow). CTPA is the best imaging procedure when pulmonary embolus is suspected. (From Vilensky, J. A., Weber, E. C., Carmichael, S. W., & Sarosi, T. E.
[2010]. Medical imaging of normal and pathologic anatomy. Philadelphia, PA: Elsevier.)
Ventilation-Perfusion Lung Scan Findings
Although the ventilation-perfusion (V/Q) lung scan has largely been replaced by the CTPA scan (see previous section), Fig. 21.6 provides a nice example of how one or more pulmonary emboli might appear on the V/Q lung scan. In this case, Fig. 21.6 (V) shows how the radioactive gas xenon-133, confirmed normal lung ventilation—that is, a black appearance throughout both lungs. By contrast, Fig. 21.6 (P) shows how the intravenous radiolabeled particles (a gamma-emitting
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isotope, usually iodine or technetium) confirmed multiple peripheral subsegmental pulmonary emboli—that is, the white areas interspersed throughout the black areas of the lungs.
FIGURE 21.6 Fat embolism in a patient with dyspnea and hypoxemia after a recent orthopedic procedure. Perfusion (P) and ventilation (V) radionuclide scans show multiple peripheral subsegmental perfusion defects suggestive of fat embolism. (From
Hansell, D. M., Lynch, D. A., McAdams, H. P., et al. [2010]. Imaging of diseases of the chest [5th ed.]. Philadelphia, PA: Elsevier.)
Pulmonary Angiography
Because pulmonary angiography is invasive (catheter insertion and dye injection), is time-consuming (about 1 hour), and requires a high degree of skill to administer, it is rarely performed today. The procedure requires a catheter to be advanced through the right side of the heart and into the pulmonary artery. A radiopaque dye is then rapidly injected into the pulmonary artery while serial x-ray images are taken. Pulmonary embolism is confirmed by abnormal filling within the artery or a cutoff of the artery. A dark area appears on the angiogram distal to the embolization because the radiopaque material is prevented from flowing past the obstruction (Fig. 21.7). The procedure generally poses no risk to the patient unless there is severe pulmonary hypertension (mean pulmonary artery pressure greater than 45 mm Hg) or the patient is in shock or is allergic to the contrast medium. Pulmonary angiography has primarily been replaced by the high-resolution CT scan (see earlier discussion).
FIGURE 21.7 Pulmonary emboli. Pulmonary angiogram shows numerous filling defects. Trailing ends of the occluding thromboemboli are particularly well shown (arrows). (From Hansell, D. M., Lynch, D. A., McAdams, H. P., et al. [2010]. Imaging of diseases of
the chest [5th ed.]. Philadelphia, PA: Elsevier.)
General Management of Pulmonary Embolism
Pulmonary embolism/infarction is a life-threatening condition. On admission to hospital, immediate transfer to an intensive care unit is mandatory. The treatment of pulmonary embolism usually begins with treating the symptoms. Oxygen is administered per the Oxygen Therapy Protocol (Protocol 10.1). The physician provides analgesics for pain and fluids and cardiovascular agents to correct blood pressure and cardiac rhythm disturbances if present.
Fast-acting anticoagulants, such as heparin, are given to prevent existing blood clots from growing and prevent the formation of new ones. Heparin is administered intravenously to achieve a rapid effect. High-molecular-weight heparin (unfractionated heparin) has, until recently, been the mainstay of treatment for patients with acute pulmonary embolism. The unfractionated heparin dosing must be governed by frequent monitoring of the activated partial thromboplastin time (APTT). This is because bleeding from unfractionated heparin can develop. Recently, low-molecular-weight heparins have become available (e.g., enoxaparin, dalteparin, and tinzaparin) and have been shown to be safer and more effective than unfractionated heparin for prophylaxis of DVT or pulmonary emboli. They are also more cost-effective and do not necessitate APTT monitoring. Doctors strive to achieve a full anticoagulant effect within the first 24 hours of treatment.
This is typically followed by the administration of slow-acting, oral anticoagulant warfarin (Coumadin, Panwarfarin). Heparin and warfarin are given together for 5 to 7 days, until blood tests show that the warfarin is effectively preventing
clotting. Then the heparin is discontinued. How long anticoagulants are given varies, based on each patient's condition. For example, if the pulmonary embolism is caused by a temporary risk factor, such as surgery, treatment is given for 2 to 3 months. If the cause is from some long-term condition, such as prolonged bed rest, the treatment is usually given for 3 to 6 months. Some patients may need to take anticoagulants indefinitely. For example, patients who have recurrent pulmonary embolism because of a hereditary clotting disorder may need to take anticoagulants for life. Patients taking warfarin need to have their blood tested periodically to determine if the dose needs to be adjusted.
Because many drugs can adversely interact with warfarin, the patient needs to be careful—that is, check with the physician—before taking any other drugs. Drugs that alter the blood's ability to clot include over-the-counter acetaminophens, ibuprofens, herbal preparations, and dietary supplements. In addition, foods that are high in vitamin K (which affects blood clotting), such as broccoli, spinach, and other leafy green vegetables, liver, grapefruit and grapefruit juice, and green tea, may need to be avoided.
Thrombolytic Agents
Fibrinolytic agents such as streptokinase (Streptase), urokinase (Abbokinase), alteplase (Activase), and reteplase (Retavase) actually dissolve blood clots. These systemic agents (commonly referred to as clot-busters) have proved beneficial in treating acute pulmonary embolism. These thrombolytic agents are sometimes used in conjunction with heparin. Their effect in patients with hemodynamic instability may be dramatic. Because of the excessive risk for bleeding, however, the use of fibrinolytic agents in treating pulmonary embolism is somewhat limited.
Preventive Measures
Directions to patients at high risk for developing thromboembolic disease include the following:
•Walking: If possible, the patient is encouraged to walk frequently. When riding in a car, the patient should be instructed to stop often to walk around or perform a few deep knee bends. When flying in an airplane, the patient should move around the cabin every hour or so.
•Exercise while seated: When sitting, the patient should be encouraged to flex, extend, and rotate his/her ankles or press his/her feet against the seat in front him/her. Rising up and down on the toes is a good alternative.
•Drink fluids: Drinking plenty of water to avoid dehydration, which can contribute to the formation of blood clots, should be encouraged. Patients should avoid alcohol, which also contributes to fluid loss.
•Wear graduated compression stockings: Patients should be encouraged to wear tight-fitting elastic stockings that squeeze the legs, thus helping the veins and leg muscles move blood more efficiently. Compression stockings provide a safe, simple, and inexpensive way to keep blood from stagnating. Research has shown that compression stockings used in combination with heparin are much more effective than heparin alone.
Inferior Vena Cava Filter
An inferior vena cava (Greenfield) vein filter may be surgically placed in the inferior vena cava to prevent clots being carried into the pulmonary circulation. Their effectiveness and the safety of the filter are not well established and in general are recommended only in some high-risk patients. Edema distal to the filters is a complicating factor.
Pneumatic Compression
This treatment uses thigh-high cuffs that automatically inflate every few minutes to massage and compress the veins in a patient's legs. Studies show that this procedure can significantly decrease the risk for blood clots, especially in patients who undergo hip replacement surgery.
Pulmonary Embolectomy
Surgical removal of blood clots from the pulmonary circulation (pulmonary embolectomy) is generally a last resort in treating pulmonary embolism because of the mortality rate associated with the procedure and because of the availability of fibrinolytic agents to treat pulmonary embolism.
Respiratory Care Treatment Protocols
Oxygen Therapy Protocol
Oxygen therapy is used to treat hypoxemia, decrease the work of breathing, and decrease myocardial work (see Oxygen Therapy Protocol, Protocol 10.1).
Aerosolized Medication Protocol
Both sympathomimetic and parasympatholytic agents may be used to induce bronchial smooth muscle relaxation when wheezing is present (see Protocol 10.4: Aerosolized Medication Therapy Protocol, and Appendix V on the Evolve site).
Lung Expansion Therapy Protocol
Patients who present with or develop significant atelectasis may benefit from a trial of lung hyperinflation, certainly if mechanical ventilation is instituted (see Lung Expansion Therapy Protocol, Protocol 10.3).
Pulmonary Hypertension
Pulmonary hypertension (PH) is defined as an increase in mean pulmonary artery pressure greater than 25 mm Hg (normal range 10 to 20 mm Hg) at rest. PH is a frequent complication of chronic pulmonary disease (e.g., chronic obstructive pulmonary disease [COPD] and interstitial lung disease) and is more common among women than among men at a ratio of 3 : 1. The World Health Organization divides PH into five different group classifications based on the cause and treatment options (Box 21.3).
Box 21.3
Clinical Classification of Pulmonary Hypertension*
Group 1 Pulmonary Arterial Hypertension (PAH)
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•Idiopathic
•Heritable
•Drugs and toxins induced (including methamphetamines and other diet medications)
•Associated with connective tissue disease and HIV infection
•Persistent pulmonary hypertension of the newborn (see Chapter 33, The Newborn Disorders)
Group 2 Pulmonary Hypertension Because of Left Heart Disease
•PH because of left heart disease—systolic and diastolic dysfunction
•Valvular disease
•Congenital/acquired left heart inflow/outflow tract obstruction and congenital cardiomyopathies
•Congenital/acquired pulmonary venous stenosis
Group 3 Pulmonary Hypertension Because of Lung Disease and/or Hypoxia
•Chronic obstructive pulmonary disease (COPD)
•Interstitial lung disease (ILD)
•Sleep-disordered breathing (e.g., sleep apnea)
•Alveolar hypoventilation disorders
•Chronic exposure to high altitude
Group 4 Chronic Thromboembolic Pulmonary Hypertension and Other Pulmonary Artery Obstructions
Group 5 Pulmonary Hypertension With Unclear and/or Multifactorial Mechanisms
•Polycythemia
•S/P splenectomy
•Essential thrombocythemia
•Sarcoidosis (10% of all patients)
•Lymphangioleiomyomatosis
•Vasculitis, including certain connective tissue disorders
•Myeloproliferative disorders
•Metabolic disorders
•Glycogen storage disease
•Gaucher disease
•Thyroid disorders
•Other conditions
•Chronic renal failure
•Fibrosing mediastinitis
*The World Health Organization first defined the classifications of PH in Evian, France, in 1973, and the classifications have been revised over the years. The most recent update reflects the 2015 European Society of Cardiology (ESC)/European Respiratory Society (ERS) Guidelines on the Diagnosis and Management of Pulmonary Hypertension (PH), which divides PH into five main groups according to shared pathophysiology, clinical features, and therapeutic approaches.
Diagnosis
PH can be very insidious. The patient may have mild to moderate PH for years with no remarkable signs or symptoms. Box 21.4 provides signs and symptoms associated with PH. The diagnosis of PH is based on the patient's medical and family histories, physical examination, and the results from a variety of tests and procedures. Tests such as echocardiography, chest x-ray, electrocardiograms, and right-heart catheterization may be used to diagnose PH. Table 21.3 provides an overview of tests and procedures used to diagnose PH. Exercise testing may be used to assess the severity of PH. Table 21.4 shows a PH severity rating scale.
Box 21.4
Common Signs and Symptoms Associated With Pulmonary Hypertension
General Findings
•Dyspnea (during routine activity)
•Lightheaded, dizziness, confusion
•Fatigue
•Nonproductive cough
•Hemoptysis
•Hoarseness
•Fainting or syncope
•Chest pain and decreased chest expansion
•A racing heartbeat
•Pain on the upper right side of the abdomen
•Decreased appetite
•Peripheral edema and venous distention
•Distended neck veins
•Swollen and tender liver
•Ankle and feet swelling
•Pitting edema
•Cyanosis
•Raynaud's phenomenon (blanching of the fingers on exposure to cold)
•Fluid in the abdomen.
Test and Procedure Findings
•Abnormal heart sounds
•Loud second heart sound (S2)
•Increased splitting (time delay) of the second heart sound (S2)
•Third heart sound (or ventricular gallop) (S3)
•Palpable right ventricular heave or lift
•Abnormal electrocardiographic (ECG) findings
•Sinus tachycardia
•Atrial arrhythmias
•Atrial tachycardia
•Atrial flutter
•Atrial fibrillation
•Acute right ventricular strain pattern and right bundle branch block
•P pulmonale (peaked P waves)
•Radiologic findings
•Enlargement of the pulmonary arteries
•Pulmonary edema
•Narrowing of the peripheral arteries
•Enlargement of the right ventricle and atrium (cor pulmonale)
changes associated with acute alveolar hyperventilation.
changes associated with acute and chronic ventilatory failure.
values will be lower than expected for a particular PaCO2 level.
, Arterial-venous oxygen difference; DO2, total oxygen delivery; O2ER, oxygen extraction ratio; QS/QT, pulmonary shunt fraction; 
, mixed venous oxygen saturation; VO2, oxygen consumption.
, mean pulmonary artery pressure; PCWP, pulmonary capillary wedge pressure; PVR, pulmonary vascular resistance; RAP, right atrial pressure; RVSWI, right ventricular stroke work index; SV, stroke volume; SVI, stroke volume index; SVR, systemic vascular resistance.
