The following cases and commentary, which involve pulmonary artery catheterization, are excerpted from ACP's Medical Knowledge Self-Assessment Program (MKSAP14).
Case 1: Raynaud's phenomenon
A 53-year-old woman with a 20-year history of Raynaud's phenomenon develops increasing fatigue and, for the past seven months, progressive dyspnea on exertion. She now must stop and rest while making her bed. She does not have chest pain, dizziness or palpitations. Her only medication is nifedipine, 30 mg/d.
On physical examination, pulse rate is 80/min, respiration rate is 18/min, and blood pressure is 115/78 mm Hg. Jugular venous pressure is not elevated, and there are no abnormal jugular venous waves. Lungs are clear to auscultation. On cardiac examination, the pulmonic component of the S2 is accentuated. There is a grade 2/6 holosystolic murmur heard loudest at the left lower sternal border that increases with inspiration. Skin examination reveals sclerodactyly and digital pitting. There is no lower-extremity edema, and the abdominal examination is unremarkable. Laboratory studies find hemoglobin of 11.3 g/dL (113 g/L), leukocyte count of 5500/µL (5.5 × 109/L), and platelet count of 155,000/µL (155 × 109/L).
Chest radiograph is normal. On pulmonary function testing, forced vital capacity is 82% of predicted, DLCO is 48% of predicted, and FEV1/forced vital capacity is 75%. Echocardio-gram shows normal chamber sizes, and valvular function is normal except for moderate tricuspid regurgitation. There is no pericardial effusion, and the estimated peak right ventricular systolic pressure is 60 mm Hg. On a six-minute walk test, oxygen saturation at rest and after exercise is 98% and 93%, respectively. She is able to walk 1300 ft.
Which of the following is the most appropriate next step in this patient's management?
A. Pulmonary artery catheterization.
B. High-resolution CT of the chest.
C. Prednisone, 60 mg/d.
D. Intravenous unfractionated heparin.
Case 2: Idiopathic cardiomyopathy
A 38-year-old woman with longstanding idiopathic cardiomyopathy is hospitalized with progressive shortness of breath and fatigue for the past three weeks. She has no other medical problems, and her last measured left ventricular ejection fraction was 15%. Her medications include lisinopril, carvedilol, spironolactone and furosemide.
On examination, the temperature is 36.8°C (98.3°F), heart rate is 105/min and systolic blood pressure is 76 mm Hg. The lungs are clear. Cardiac examination reveals regular rhythm, normal S1 and S2, and the presence of an S3. There is mild edema at both ankles, and extremities are cool. Laboratory results include sodium, 130 mEq/L (130 mmol/L); blood urea nitrogen, 78 mg/dL (27.85 mmol/L); and creatinine, 3.1 mg/dL (274.1 µmol/L). Her baseline creatinine is approximately 1.2 mg/dL (106.1 µmol/L). Electrocardiogram shows sinus tachycardia without acute changes.
Which diagnostic test would be most useful in diagnosing the cause of the patient's volume status?
A. Measurement of plasma B-type natriuretic peptide.
B. Pulmonary artery catheterization.
C. Coronary angiography.
D. Ventilation/perfusion scan.
Case 3: Perioperative management
A 72-year-old man who had a myocardial infarction six months ago is scheduled to undergo resection of an abdominal aortic aneurysm. He has the following surgical risk classifications: Goldman Cardiac Risk class II, American Society of Anesthesiologists class II, and New York Heart Association class II heart failure.
Placement of a pulmonary artery catheter for perioperative management is most likely to result in which of the following outcomes in this patient?
A. Decreased 28-day mortality.
B. Decreased length of ICU stay.
C. Decreased incidence of congestive heart failure.
D. No identifiable benefit.
E. Decreased incidence of perioperative renal dysfunction.
Answers and Commentary
Correct answer: A. Pulmonary artery catheterization.
The most appropriate next step in this patient's management is pulmonary artery catheterization to establish the presence of pulmonary hypertension and to evaluate the potential vascular responsiveness to aggressive vasodilator therapy. Because of her long history of Raynaud's phenomenon and limited cutaneous scleroderma, as well as the evidence of pulmonary hypertension on cardiovascular examination and echocardiography, this patient is at high risk for pulmonary vascular disease, particularly isolated pulmonary hypertension. Patients with diffuse cutaneous scleroderma have an increased risk for developing pulmonary vascular disease, as well, but the risk is higher in those with limited disease.
High-resolution CT will help to evaluate the pulmonary parenchyma but cannot definitively establish a diagnosis of pulmonary hypertension. In addition, there are no findings on pulmonary examination to suggest this diagnosis. Crackles or “velcro rales” are commonly heard in patients with interstitial lung disease and almost always precede the development of secondary pulmonary hypertension.
Immunosuppressive therapy with prednisone is not indicated, because the pulmonary vasculopathy of scleroderma is not related to an inflammatory disorder. Moreover, high-dose corticosteroid therapy in the setting of scleroderma may be associated with normotensive renal crisis. Intravenous heparin is not indicated because this patient does not have clinical suspicion for an acute pulmonary thromboembolic event. Warfarin therapy should be considered in the long-term management of a patient with pulmonary hypertension. However, anticoagulation using intravenous heparin is not useful in the acute setting.
- Patients with a long history of Raynaud's phenomenon and diffuse or limited cutaneous scleroderma are at risk for pulmonary vascular disease.
- High-dose corticosteroid therapy in the setting of scleroderma may be associated with normotensive renal crisis.
Correct answer: B. Pulmonary artery catheterization.
Management of cardiogenic shock includes treating the underlying cause, correcting hypotension, improving intracardiac filling pressures, and improving end-organ perfusion. The hemodynamic information provided by a pulmonary artery catheter is particularly useful when the patient's volume status—and thus appropriate treatment—is uncertain. This patient's symptoms and findings do not clearly point to a specific disease status. They may be due to volume overload or low output. Hyponatremia in this case is indicative of severe heart failure. It should be noted that the ultimate effect of pulmonary artery catheter use on short- and long-term mortality in critically ill patients is not definitively established.
Measurement of B-type natriuretic peptide (BNP) may be useful to diagnose decompensated heart failure with volume overload, but renal failure causes elevated BNP levels, making interpretation of the level difficult in this setting. In addition, although BNP level may help diagnose volume overload, it does not yield detailed hemodynamic data that would clarify the hemodynamic derangement and assist in titrating vasoactive medications. Coronary angiography would be useful in cases of acute myocardial infarction or acute coronary syndrome associated with cardiogenic shock.
However, the likelihood of coronary artery disease is low given the patient's young age and absence of risk factors; in addition, the electrocardiogram is remarkable for sinus tachycardia only and does not demonstrate any acute changes suggestive of ischemia or infarct. A ventilation/perfusion scan would be useful to evaluate for pulmonary embolus. However, the patient does not have any signs or symptoms of pulmonary embolus, which, in any case, would not account for the hyponatremia and acute renal failure.
- A pulmonary artery catheter is useful in the management of heart failure when the patient's volume status is uncertain.
- In addition to treatment of a specific cause, treatment of cardiogenic shock includes correcting hypotension, improving intracardiac filling pressures, and improving end-organ perfusion.
Correct answer: D. No identifiable benefit.
Placing a pulmonary artery catheter would likely have no benefit in this patient. Over the past 30 years, the pulmonary artery catheter became a widely used hemodynamic monitoring device in the management of critically ill patients, although doubts exist about its utility and safety. Three large, multi-center, randomized controlled trials of critically ill ICU patients have shown no mortality or outcomes benefits from management guided by placement of a pulmonary artery catheter. Although the catheter may still have a role in a selected minority of patients, routine placement of these devices is not appropriate. Whether care was done by protocol with specific hemodynamic goals or not, and regardless of admission diagnosis or hemodynamic profile, there was no identifiable advantage in any of these trials to having pulmonary artery catheter-guided therapy.
- Placement of a pulmonary artery catheter in critically ill ICU patients has not been shown to have a benefit on mortality or other outcomes.