Correspondence
Diagnosis of Pulmonary Embolism
N Engl J Med 1998; 339:1084-1085October 8, 1998
- Article
To the Editor:
The Clinical Problem-Solving case presented by Yu et al. (June 4 issue)1 regarding the diagnosis and treatment of pulmonary embolism did not address a recently developed diagnostic technique for the evaluation of pulmonary emboli that can obviate the need for angiography. Spiral computed tomographic (CT) scanning of the pulmonary arteries for the diagnosis of central emboli has been performed over the past few years with high accuracy.2,3 The accuracy of spiral CT for the diagnosis of peripheral emboli is less than that for central emboli; the clinical importance of peripheral emboli is controversial.
3 ReferencesMartin A. Schwartz, M.D.
Hollywood Community Hospital, Hollywood, CA 900281
Yu DR ,Miller R ,Bray PF . Through thick and thin. N Engl J Med 1998;338:1684-1687
Full Text | Web of Science | Medline2
Rubin SA . 1996 Plenary session: imaging symposium, chest radiology update. Radiographics 1997;17:1015-1036
Web of Science3
Ferretti GR ,Bosson J-L ,Buffaz P-D , et al. Acute pulmonary embolism: role of helical CT in 164 patients with intermediate probability at ventilation-perfusion scintigraphy and normal results at duplex US of the legs. Radiology 1997;205:453-458
Web of Science | Medline
To the Editor:
Yu et al. used the alveolar–arterial oxygen gradient to support the diagnosis of pulmonary embolism. If their patient inhaled room air at sea level, the arterial partial pressure of carbon dioxide of 38 mm Hg would correspond to an alveolar partial pressure of oxygen of 102 mm Hg; the alveolar–arterial oxygen gradient is then 13 mm Hg, which is a normal value.1 However, several series have concluded that having normal values for the alveolar–arterial oxygen gradient does not preclude the diagnosis of pulmonary embolism.1
The authors' argument that the discussant maintained a high index of suspicion, with an emphasis on diagnostic sensitivity despite the normal chest film and normal electrocardiogram, is misleading. The primary role of radiography and electrocardiography in the setting of pulmonary embolism is to eliminate other diagnoses, such as pneumothorax or myocardial infarction.2 The chest films and electrocardiograms in the majority of patients with acute pulmonary embolism are normal.2-4 When they are abnormal the findings are most often too subtle and nonspecific to allow the diagnosis of pulmonary embolism to be made.3,4 Therefore, finding them to be normal in the patient described is in accord with a diagnosis of pulmonary embolism, and pursuing a diagnostic workup for pulmonary embolism at that point had nothing to do with diagnostic sensitivity and the maintenance of a high index of suspicion as the authors claim.
4 ReferencesOren Zimhony, M.D.
Albert Einstein College of Medicine, Bronx, NY 104611
Stein PD ,Goldhaber SZ ,Henry JW . Alveolar-arterial oxygen gradient in the assessment of acute pulmonary embolism. Chest 1995;107:139-143
CrossRef | Web of Science | Medline2
Moser KM . Venous thromboembolism. Am Rev Respir Dis 1990;141:235-249
Web of Science | Medline3
Greenspan RH ,Ravin CE ,Polansky SM ,McLoud TC . Accuracy of the chest radiograph in diagnosis of pulmonary embolism. Invest Radiol 1982;17:539-543
CrossRef | Web of Science | Medline4
McIntyre KM ,Sasahara AA ,Littmann D . Relation of the electrocardiogram to hemodynamic alterations in pulmonary embolism. Am J Cardiol 1972;30:205-210
CrossRef | Web of Science | Medline
To the Editor:
Yu et al. presented the case of a patient with pulmonary embolism who was ultimately given a diagnosis of antiphospholipid syndrome. Although the clinical presentation is consistent with this diagnosis, the laboratory data as presented do not allow this diagnosis to be made with confidence. The diagnosis of antiphospholipid syndrome requires the demonstration of either a lupus anticoagulant by a clotting assay or antiphospholipid antibodies by enzyme-linked immunosorbent assay (ELISA). Regarding the former, the recommended diagnostic criteria are a prolongation of a phospholipid-dependent coagulation reaction, such as the dilute Russell's viper–venom time (DRVVT); a lack of correction of a prolonged screening assay after a 1:1 mix with pooled normal plasma; and a correction of a prolonged screening assay by the addition of excess phospholipid.1 For the patient Yu et al. described, the isolated, mildly prolonged DRVVT is insufficient for the demonstration of a lupus anticoagulant.
With respect to antiphospholipid antibodies demonstrated by ELISA, the actual result of the ELISA for anticardiolipin antibody should be provided rather than an interpretation of the data. Furthermore, several authors recommend obtaining two positive tests that demonstrate antiphospholipid antibodies at two separate times before classifying a patient as having the antiphospholipid syndrome, since antiphospholipid antibodies can appear transiently in normal persons. Many patients are given a diagnosis for which supportive data cannot be subsequently confirmed.
1 ReferencesStephan Moll, M.D.
Humboldt Universität Charité, 13122 Berlin, GermanyThomas L. Ortel, M.D., Ph.D.
Duke University Medical Center, Durham, NC 277101
Brandt JT ,Triplett DA ,Alving B ,Scharrer I . Criteria for the diagnosis of lupus anticoagulants: an update. Thromb Haemost 1995;74:1185-1190
Web of Science | Medline
To the Editor:
The role of pleuritic chest pain in the diagnosis of pulmonary embolism is generally overestimated. In outpatients presenting with pleuritic pain, only a minority have pulmonary embolism (between 2 and 21 percent).1,2 Only about two thirds of patients with pulmonary embolism have pleuritic pain.3 The syndrome of “central chest pain,” however, is generally underappreciated. We define central chest pain as nonpleuritic chest pain or discomfort, which some patients describe as anginal and some as a difficulty in breathing (often despite the absence of objective dyspnea or tachypnea). Central chest pain may be a presenting feature of newly diagnosed pulmonary hypertension (irrespective of cause).
From a clinical-management point of view,4 it is useful to classify pulmonary embolism into two groups: “big” embolism and “small” embolism; more specifically, the effect and signs of pulmonary embolism will depend on the size of the embolus and the coping capacity of the cardiopulmonary system. The risk of death is high with big emboli, but low with small emboli. Pleuritic pain strongly suggests peripheral (small) emboli, whereas central chest discomfort points toward more central (bigger) emboli. In other words, central chest pain indicates a more serious condition than pleuritic pain.
In the case under discussion, the patient presented with presyncope and central chest pain. Along with coronary ischemia, relevant pulmonary embolism had to be placed at the top of the differential-diagnosis list.
4 ReferencesChristoph Pechlaner, M.D.
Walter Gritsch, M.D.
Christian Wiedermann, M.D.
Innsbruck University Hospital, A-6020 Innsbruck, Austria1
Thomas L ,Reichl M . Pulmonary embolism in patients attending the accident and emergency department with pleuritic chest pain. Arch Emerg Med 1991;8:48-51
Medline2
Hull RD ,Raskob GE ,Carter CJ , et al. Pulmonary embolism in outpatients with pleuritic chest pain. Arch Intern Med 1988;148:838-844
CrossRef | Web of Science | Medline3
Stein PD ,Terrin ML ,Hales CA , et al. Clinical, laboratory, roentgenographic, and electrocardiographic findings in patients with acute pulmonary embolism and no pre-existing cardiac or pulmonary disease. Chest 1991;100:598-603
CrossRef | Web of Science | Medline4
Ruckley CV . Management of pulmonary embolism. BMJ 1982;285:831-833
CrossRef | Web of Science | Medline
Author/Editor Response
The authors reply:
To the Editor: We agree with Dr. Schwartz that spiral CT may be a useful tool for the initial diagnostic evaluation of pulmonary embolism. Although studies have been conducted that demonstrate the accuracy of spiral CT to be equivalent to and perhaps better than that of ventilation perfusion scanning, they were limited by their small size.1 Our experience suggests that pulmonary angiography is the most reliable diagnostic tool, and given the dangers of heparin in our patient with thrombocytopenia and active bleeding, we believed it was imperative to obtain a definitive diagnosis with an angiogram.
Dr. Zimhony's calculation of the alveolar–arterial gradient was based on the assumption that the patient was breathing room air. However, as stated in our article, the arterial-blood gas level was obtained while the patient was breathing 4 liters of oxygen per minute. If one estimates the fractional concentration of inspired oxygen to be 32 percent, the alveolar–arterial gradient is 92 mm Hg — clearly abnormal. We agree that although chest radiography and electrocardiography are not sensitive tools for diagnosing pulmonary embolism, they help rule out other causes of chest pain. Our patient did not have the more classic symptoms of pulmonary embolism, such as dyspnea, a typical finding in larger studies that have concluded that isolated chest pain remains a very sensitive (but nonspecific) marker of pulmonary embolism.2 The suggestion by Pechlaner et al. that pulmonary emboli often present with central chest pain as opposed to pleuritic chest pain underscores the importance of recognizing the various manifestations of this disease. A good clinician will be served well by always maintaining a strong index of suspicion for pulmonary emboli.
2 ReferencesDavid R. Yu, M.D.
Redonda Miller, M.D.
Paul F. Bray, M.D.
Johns Hopkins Hospital, Baltimore, MD 21205-21961
Mayo JR ,Remy-Jardin M ,Muller NL , et al. Pulmonary embolism: prospective comparison of spiral CT with ventilation-perfusion scintigraphy. Radiology 1997;205:447-452
Web of Science | Medline2
Palla A ,Petruzzelli S ,Donnamaria V ,Giuntini C . The role of suspicion in the diagnosis of pulmonary embolism. Chest 1995;107:Suppl:21S-24S
CrossRef | Web of Science | Medline
