Respiration 37: 309-317 (1979)
Accuracy of Screening for Pulmonary Embolism in the Emergency Room1 Tee L. Guidotti, Louis F. Fries, William R. Bell, Hubert T. Gurley and Andrew Pachner The Johns Hopkins Hospital, Baltimore, Md.
Key Words. Pulmonary embolism • Thrombosis • Dyspnea ■Diagnosis • Emergency care • Chest pain
Certain management problems occur fre quently in the emergency room. One of the most troublesome involves the patient who might have had a pulmonary embolus. No reasonable physician would fail to admit and to treat an acutely hypoxemic, hypotensive patient with a history of throm 1 Supported in part by grant No. HL 01601 from the NHLBI of the National Institutes of Health. We thank the Osier housestaff of the Johns Hop kins Hospital for their essential cooperation.
bophlebitis. On the other hand, few would admit a healthy-appearing young person with mild pleuritic chest pain but free of tachypnea, oxygen desaturation, and predis posing conditions. Between these two ex tremes, the threshold for admitting a patient with acute shortness of breath and chest pain varies greatly among physicians. Recent series have demonstrated that the prognosis for patients with pulmonary embolism who survive long enough to be
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Abstract. Pertinent historical, clinical, and laboratory findings were recorded for 37 consecutive patients who presented to the emergency room complaining of shortness of breath and chest pain but without evidence of coronary insufficiency, pneumonia, or mus culoskeletal injury. 13 had pulmonary embolism suggested by lung scan with or without pul monary angiogram, or, in 2 cases, by right heart catheterization. As a group, these patients in whom embolism was judged probable approached fairly closely the profiles of previous studies of patients with documented pulmonary emboli. Nonetheless, they differed very little, and in no clinically useful way short of lung scans and invasive studies, from the remaining 24 patients in whom embolism was judged unlikely. In the population served by this emergency room, which has a high morbidity from chest diseases and putative pre disposing conditions to pulmonary embolism, screening patients for high and low probability groups for this diagnosis cannot be done on clinical grounds alone. Six-projection ventila tion-perfusion lung scanning may be the only acceptable screening examination, and should be available directly from the emergency room in hospitals with an active emergency service.
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treated is quite good [1, 2]. Thus, the classi fication of the individual patient into high and low probability categories on initial presentation is a matter of some urgency. When this problem emerged repeatedly as a major management issue in the Emergency Room of The Johns Hopkins Hospital, we examined our experience and practices in order to propose reasonable guidelines to improve our handling of such patients.
Materials and Methods 37 consecutive patients who presented to the Emergency Room of The Johns Hopkins Hospital in Baltimore from September 1976 to March 1977 were enrolled in the study. All presented with com plaints of chest pain and shortness of breath and
had obvious chest wall disease, pneumonia, and coronary insufficiency excluded by physical exam ination, chest film, and ECG. Witnessed verbal and written informed consent for participation was obtained from each patient; none refused. The patients were interviewed for historical features and symptoms using questions directed toward the predisposing conditions listed in table I and the symptoms listed in table II. Whenever possible the interview data were confirmed by family members or the medical record. The ques tions were drawn from the Urokinase Pulmonary Embolism Trial, of which this institution was a part [3]. The study team representative then performed a focused physical examination in addition to that of the house officer attending the patient. The signs given in table II were noted and recorded with the results of the laboratory data itemized in table III. 13 patients were assigned to the ‘high probabil ity’ group, 8 on the basis of six-projection ventila-
Table I. Correlation of known predisposing factors with probability of pulmonary embolism
Total Male Female Lower extremity thrombophlebitis, active Chronic venous insufficiency Congestive heart failure Prolonged bed rest Chronic obstructive pulmonary disease Pulmonary embolism in past Pelvic disease or surgery Lower extremity trauma or surgery, > 6 months past Lower extremity trauma or surgery, < 6 months past Cancer, diagnosis known Estrogen medication Postpartum, < 6 months
High probability1
Low probability
n
n
13 7 6 62 52 43 3 33 3* 2 2 2 1 0 0
% 100 54 46 46 39 31 23 23 23 15 15 15 8 0 0
24 8 16 8 10 4 4 8 5 8 4 4 2 2 1
% 100 35 65 33 42 17 17 33 21 33 17 17 8 8 4
1 Classification on the basis of lung scan with or without pulmonary arteriogram in all but 2 cases (see below and text). 2 Includes 1 case in which classification made by right heart catheterization. 3 Includes the other case in which classification made by right heart catheterization.
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tion and perfusion lung scans interpreted as diag nostic or ‘high probability’ by our institution’s published criteria [4], 3 on the basis of suggestive lung scans confirmed by positive pulmonary arte riograms, and 2 on the basis of right heart cathe terization performed in the intensive care unit, both with recent histories of documented pulmonary emboli. These 13 patients constitute the popula tion we considered to be in the high probability category for having suffered pulmonary embolism. 24 patients were assigned to the ‘low probabili ty’ group, 22 on the basis of normal lung scans
and 2 on the basis of obvious alternative diagnos es, specifically the discovery after admission of early pneumonia and of metastatic carcinoma. These 24 patients constitute the population we considered to be in the low probability category for pulmonary embolism. The two groups were compared with each other and with previous re ports [3, 5-10J. The disposition of each patient was left to the discretion of the physician in attendance. The study representative did not intervene in manage ment decisions. Thus, the study represents the ac-
Table II. Presenting symptoms and signs on physical examination, correlated with probability group. (Chest pain and shortness of breath were criteria for inclusion into the study)
Symptoms Dyspnea, sudden onset Chest pain, vague substernal Chest pain, pleuritic Leg pain or cramping Hemoptysis Cough, sudden onset Signs Tachycardia ( > 100) Diaphoresis Rales, focal Thrombophlebitis, lower extremity Wheezing Accentuated pulmonic component of S2 Cyanosis Pleural rub Vital signs (mean ± SD) Pulse Temperature Respiratory rate Blood pressure, systolic Blood pressure, diastolic
High probability1
Low probability
n
%
n
%
113 73 6 5 4 2123
85 54 46 39 31 15
16 11 15 7 5 10
70 48 65 30 22 44
93 73 53 3 23 2 22 0
69 54 39 23 15 15 15 0
7 10 6 5 5 2 2 1
30 44 26 22 22 9 9 4
100.5 ± 37.1 ± 24.4 ± 138.9 ± 88.5 ±
16.3 0.9 6.1 35.4 23.8
92.7 ± 38.9 ± 22.3 ± 141.2 ± 86.8 ±
16.8 1.0 8.5 30.2 20.9
1 Classification on the basis of lung scan with or without pulmonary arteriogram in all but 2 cases (see below and text). 2 Includes 1 case in which classification made by right heart catheterization. 3 Includes the other case in which classification made by right heart catheterization.
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Finding
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Table III. Laboratory data correlated with probability of pulmonary embolism Laboratory test
High probability1
Low probability
n
n
%
%
Arterial blood gas tensions (mean ± SD) PaC>2 PaCOz pH Prothrombin time, % control Hematocrit, %
68.2 27.7 7.43 75 38.1
Chest films Atelectasis No abnormality Pleural effusion Infiltrate Cardiomegaly
53 4 2 2123 1
38 31 15 15 8
1 11 4 2 2
4 48 17 9 9
Electrocardiogram Nonspecific ST-T wave changes Peaked P wave in II Normal S in I, Q and T in III Clockwise rotation of axis New right bundle branch block New right axis deviation Right ventricular ‘strain’
73 42 3 22 2 2 1 I
54 31 23 15 15 15 8 8
8 1 10 2 2 0 0 0
35 4 44 9 9 0 0 0
± ± ± ± ±
14.1 5.0 0.04 25 5.8
69.3 31.0 7.46 77 40.8
± ± ± ± ±
13.9 7.2 0.05 21 5.7
tual practice at our institution and not a planned protocol. Patients who were admitted to the hospi tal were followed by the study team. Those who were not admitted were contacted by the study team by telephone in 1 week for follow-up infor mation.
Results A total of 37 patients were enrolled in the study, of whom 54% were women. Ages ranged from 18 to 76 with a mean of 49.0
years. Pulmonary embolism was judged probable in 13 patients, 46% of whom were women, with a mean age of 67.8 (range 56-71), and 54% men, with a mean age of 46.0 (range 25-65). 2 patients died in the high probability group, both within 3 days of admission with the clinical impression of recurrent massive embolism despite ade quate anticoagulation. Pulmonary embolism was judged not to be probable in 24 patients, 65% women, with an aggregate mean age of 45.7 (range
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1 Classification on the basis of lung scan with or without pulmonary arteriogram in all but 2 cases (see below and text). 2 Includes 1 case in which classification made by right heart catheterization. 3 Includes the other case in which classification made by right heart catheterization.
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Table IV. Comparison of predisposing factors for pulmonary embolism (percent values) Characteristic
Sasahara el al., 1962 (6] Dalai el al., 1977 [8] n = 72» n = 41
Lower extremity thrombophlebitis Chronic venous insufficiency Prolonged recent bed rest Chronic obstructive pulmonary disease Past history of pulmonary embolism Congestive heart failure Pelvic disease or surgery Lower extremity manipulation, > 6 months previously Lower extremity manipulation. < 6 months previously Estrogenic medication Known cancer Postpartum, < 6 months
10 17 24
_
US Trials, 1977 [9) n = 327
~
40 15 8 8 26 17 6
~
3
_2
-
45 14 20
-
5 7 1
1 All but 1 patient were males. 2 In this report it is not clear from the text how many patients had preexisting congestive failure. 69% are reported to have had ‘heart disease’ in general, and 35% presented with symptoms mimicking congestive failure which were apparently related to their pulmonary embolism.
on physical examination are noted in table II. Laboratory data, including the chest film and ECG, are shown in table III.
Discussion One is immediately struck by how poorly the presence of putative predisposing fac tors is correlated with the ultimate judge ment of how likely it is that pulmonary em bolism has occurred. Although each is well documented in the literature [3, 5-9], none of the predisposing factors proved to be a reliable guide in this patient population, even when compared by sex. Pulmonary embolism appears to be pre dominantly a disease of older women and younger men in noninstitutionalized patients.
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18-76). There were no deaths in the low probability group. The leading alternative diagnosis in the low probability group was viral pleuritis (3), with chronic bronchitis (2), pericarditis, metastatic carcinoma, congestive heart failure, and pneumonia also seen. The remaining patients had no specific diagnosis confirmed; they were gen erally below the age of 35, women, and all did well. No patient was sent home from the Emergency Room who later became ill. The correlation between generally ac cepted predisposing conditions (comorbid states) and the eventual assignment into high and low probability groups for pul monary embolism is given in table I. Fur ther breakdown by sex did not reveal any specific trends different from the aggregate figures. The presenting symptoms and signs
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Table V. Comparison of data from various studies on signs, symptoms, and laboratory findings in pulmonary embolism (percent values). Characteristic
Gorham, 1961 [5] n = 1001
Sasahara e lal., Szucs el a/., Dalen et al., US Trials 1967 [6] 1967 (71 1977 [8] 1977 [9J n = 72 n = 50 n = 41 n = 327
Dyspnea, acute Chest pain, vague Chest pain, pleuritic Hemoptysis Cough, acute Tachycardia (> 100) Diaphoresis Rales, focal LE phlebitis Accentuated Pa Cyanosis Pleural rub
20 26 12
100
-
-
55 42 72 65
57 19
19 -
9
70 33 80 15 15
-
14 29 35 51
_
Electrocardiogram NS ST-T W J s 3 P-pulmonale in II SiQTiu ‘Clockwise’ rotation New RBBB New RAD Right vent, ‘strain’
Blood gases4 PaOa (torr) PaCOa (torr)
-
_
Chest film Normal Pleural effusion Infiltrate Abnormal, nonspecific
Vital signs4 Temperature Pulse Respiratory rate BP, systolic BP, diastolic
-
_ -
44
_
84 14 74 30 53 44 27 58 32 53 19 7 51 54
_
-
-
10
4 11 28 16 5
-
8 15
‘fever’ in 45 %5 >90 in 65% >20 in 65%
37.7 98.9 25.5 124.5 77.2 61 ± 29 37 ± 14
59.4 ±14.1 7.40 in 92%
1 Selected for fatal outcome. 2 Some results shown here have been recalculated from the published data. 3 Nonspecific ST-T wave changes. 4 Mean ± standard deviation. 5 ‘Fever’ not clearly defined.
>70 9 3 6 0 -
± ± ± ± ±
0.8 18.9 106 ± 4 8.8 20.8 13.3
61.2 ±14.2
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-
-
-
Ahonen, 1977 [10] n = 3512
The sex and age distribution of our popula tion with embolism judged probable was similar to that of the Urokinase-Strep tokinase Pulmonary Embolism Trials [9]. The relatively low mortality from treat ed embolism in our study is in keeping with previous reports [1]. Our patients had a high frequency of lower extremity venous disease in the high probability group, but so did an unexpected ly large number of patients in the low prob ability group, especially women (44°/o). Our high probability group was more likely to have had congestive heart failure, pelvic disease, and chronic venous insufficiency than the group with embolism diagnosed in the Trials, and was less likely to have had re cent immobilization or oral contraceptives; they were as likely to have had a malignan cy. By comparison, our embolism low prob ability group matched or exceeded the fre quency of predisposing factors in the high probability group except for bed rest and congestive failure. The most probable ex planation, assuming that these comorbid states are truly predisposing (and evidence from the Trials suggests that perhaps recent termination of pregnancy is not) [9], is that our study population has such a high prev alence of these medical problems that the history did not serve as a useful discrimi nant in individual cases. Presenting signs and symptoms were lit tle better. None of the cardinal findings of pulmonary embolism reliably suggested the diagnosis, nor did their absence reliably ex clude it. Table V presents the comparable data for similar, larger published studies, in cluding the Trials [9] and that of Sasahara et al. [6], Our high probability population had as frequent dyspnea and hemoptysis, less frequent chest pain (and less often pleu
315
ritic) and cough than the patients with em bolism diagnosed in the Trials. Again, the distribution of these symptoms in our low probability group is remarkably similar to our high probability group and also to the Trials. The physical findings in our high probability group are more generally consis tent with the findings of the Trials. Our pa tients had tachycardia and diaphoresis more often than the patients with embolism con firmed in the Trials, and focal rales, active thrombophlebitis, and accentuation of the pulmonic component of the second heart sound less often than the patients in the Trials and much less often than the patients in whom pulmonary embolism was diag nosed in Sasahara et al. [6] Cyanosis was present equally in both groups.The high prob ability group patients also had these findings more often than the low probability group patients. Despite these group differences, the vital signs were not statistically different between them, raising questions as to the usefulness of fever, tachypnea, and tachy cardia in implying the diagnosis. It should also be noted that fever, pleuritic chest pain, and cough may be features of a viral pleuritis. one of the leading alternative diagnoses. Laboratory data customarily obtained in our Emergency Room contributed little. The blood gases were of limited value; the mean Pao2 was surprisingly low in the low probability group, suggesting that the diag nostic dilemma occurs regularly in patients with intrinsic lung disease. The mean Pao2 and standard deviation for patients with confirmed pulmonary embolism have been remarkably reproducible between studies, but hypoxemia remains a nonspecific find ing in the individual patient. The hematocrit and prothrombin time were of no help, al though detection of polycythemia or a coa
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Accuracy of Screening for Pulmonary Embolism in the Emergency Room
gulopathy might have been clinically useful had either been present in a patient. The chest film was of little use in assign ing the patients to probability groups. Again, this is probably because the diagnos tic dilemma arises often in patients with es tablished pulmonary or cardiovascular dis ease. Patients in whom the diagnosis was ul timately judged probable tended to have more abnormalities in general, particularly discoid atelectasis, but this was not helpful in managing the individual patient. Almost one third of the patients in the high proba bility group had normal chest films. The ECG was somewhat, but not much, more helpful. More patients in the high probability group had an abnormal ECG, and the specific abnormalities were those of right ventricular and right atrial disturbance (or ‘strain’). Inevitable questions ob bias must be ad dressed in this study. The population is small compared to those of the multicenter studies, but compatible with our intent to examine clinical practice in a nonidealized sample. From a clinician’s standpoint, there is a practical limit to the utility of large mul ticenter studies. Although these are enor mously valuable in advancing our under standing of the pathophysiology and incid ence of the disease, clinical findings and dis tinctions which require huge numbers of pa tients to document are not very helpful in practice. We have relied upon lung scanning in assigning most of our patients to high and low probability categories. This is an accur ate reflection of clinical practice at this in stitution, where the statistical limitations of the technique have been described in detail compared to pulmonary arteriography [4], Clearly, an error rate even twice that docu mented for this institution would not sub
Guidotti/Fries/Bcll/Gurley/Pachner
stantially alter the trends (or lack thereof) that we have observed. Furthermore, the in tent of this study was not to assess the utility of historical, clinical, and laboratory find ings in confirming the diagnosis of pulmon ary embolism, but rather to identify factors which might, singly or in combination, sug gest that the patient be assigned to a high probability category which should be inves tigated further as an inpatient. In an age where restrictions are placed on the expansion of clinical facilities, medi cal wards are subject to fluctuating census, and cost containment is a major issue, ad missions which do not lead to a useful inter vention should be avoided. We have shown that the usual historical, clinical, and labo ratory findings associated with pulmonary embolism are not reliable to screen patients for admission. The overriding consideration of patient welfare therefore requires that a relatively high frequency of admissions for patients in whom embolism is ultimately ruled out must be tolerated, so that virtually all of those with the disease will be treated. The partial answer to this trade-off may be to increase the availability of outpatient lung scans, specifically six-projection ven tilation-perfusion scans with access directly from the emergency room on an urgent ba sis [11, 12]. This is a costly alternative, however, requiring access to a facility which is already much in demand. Nonetheless, it is clear that the diagnosis of pulmonary em bolism can be screened in no other way, and that patients cannot be assigned to high and low probability groups for the diagnosis by the usual laboratory and clinical findings available in the emergency room. We remain strong believers in the value of a comprehensive evaluation and educated clinical judgement. Nonetheless, we are
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Accuracy of Screening for Pulmonary Embolism in the Emergency Room
Acknowledgement We are grateful to the housestaff on the Osier service of The Johns Hopkins Hospital, whose cooperation, interest, and tradition of independent investigation made this study possible.
References 1 Alperts, J. S., et al.: Mortality in patients treated for pulmonary embolism. J. Am. mcd. Ass. 236: 1477-1480 (1976). 2 Sutton, G. C.: Clinical course and late progno sis of treated subacute massive, acute minor, and chronic pulmonary thromboembolism. Br. Heart J. 39: 1135-1142 (1977). 3 Urokinase Pulmonary Embolism Study Group: Urokinase pulmonary embolism trial. Circula tion 49: suppl. 2 (1974). 4 Poulose, K. P., et al.: Diagnosis of pulmonary embolism. Br. med. J. iii: 67-71 (1970). 5 Gorham, L. W.: A study of pulmonary embo lism. Archs intern. Med. 108: 76-97 (1961). 6 Sasahara, A. A., et al.: Clinical and physiolog ic studies in pulmonary thromboembolism. Am. J. Cardiol. 20: 10-20 (1967).
7 Szucs, M. M., et al.: Diagnostic sensitivity of laboratory findings in acute pulmonary embo lism. Ann. intern. Med. 74: 161-166 (1971). 8 Dalen, J. E., et al.: Pulmonary embolism, pul monary hemorrhage and pulmonary infarction. New Engl. J. Med. 296: 1431-1435 (1977). 9 Bell, W. R., Simon, T. L., and DeMets, D. L.: The clinical features of submassive and mas sive pulmonary emboli. Am. J. Med. 62: 355-360 (1977). 10 Ahonen, A.: Electrocardiographic changes in massive pulmonary embolism. I. Analysis of the changes in P wave and QRS complex. II. Analysis of the changes in ST segments and T wave. Acta med. scand. 201: 539-542, 543-545 (1977). 11 Moser, K. M., et al.: Differentiation of pul monary vascular from parenchymal diseases by ventilation: perfusion scintigraphy. Ann. in tern. Med. 75: 597-605 (1971). 12 Bell, W. R. and Simon, T. L.: A comparative analysis of pulmonary perfusion scans with pulmonary angiograms. Am. H eart J. 92: 700-706 (1976).
Received: June 13, 1978 Accepted: September 29, 1978 William R. Bell, MD, The Johns Hopkins Hospital, 601 N. Broadway, Baltimore, MD 21205 (USA)
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forced to conclude that at the present state of the art screening for pulmonary embo lism rests solely on a diagnostic procedure.
317
Accuracy of Screening for Pulmonary Embolism in the Emergency Room1 Tee L. Guidotti, Louis F. Fries, William R. Bell, Hubert T. Gurley and Andrew Pachner The Johns Hopkins Hospital, Baltimore, Md.
Key Words. Pulmonary embolism • Thrombosis • Dyspnea ■Diagnosis • Emergency care • Chest pain
Certain management problems occur fre quently in the emergency room. One of the most troublesome involves the patient who might have had a pulmonary embolus. No reasonable physician would fail to admit and to treat an acutely hypoxemic, hypotensive patient with a history of throm 1 Supported in part by grant No. HL 01601 from the NHLBI of the National Institutes of Health. We thank the Osier housestaff of the Johns Hop kins Hospital for their essential cooperation.
bophlebitis. On the other hand, few would admit a healthy-appearing young person with mild pleuritic chest pain but free of tachypnea, oxygen desaturation, and predis posing conditions. Between these two ex tremes, the threshold for admitting a patient with acute shortness of breath and chest pain varies greatly among physicians. Recent series have demonstrated that the prognosis for patients with pulmonary embolism who survive long enough to be
Downloaded by: King's College London 137.73.144.138 - 11/21/2017 8:40:13 AM
Abstract. Pertinent historical, clinical, and laboratory findings were recorded for 37 consecutive patients who presented to the emergency room complaining of shortness of breath and chest pain but without evidence of coronary insufficiency, pneumonia, or mus culoskeletal injury. 13 had pulmonary embolism suggested by lung scan with or without pul monary angiogram, or, in 2 cases, by right heart catheterization. As a group, these patients in whom embolism was judged probable approached fairly closely the profiles of previous studies of patients with documented pulmonary emboli. Nonetheless, they differed very little, and in no clinically useful way short of lung scans and invasive studies, from the remaining 24 patients in whom embolism was judged unlikely. In the population served by this emergency room, which has a high morbidity from chest diseases and putative pre disposing conditions to pulmonary embolism, screening patients for high and low probability groups for this diagnosis cannot be done on clinical grounds alone. Six-projection ventila tion-perfusion lung scanning may be the only acceptable screening examination, and should be available directly from the emergency room in hospitals with an active emergency service.
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treated is quite good [1, 2]. Thus, the classi fication of the individual patient into high and low probability categories on initial presentation is a matter of some urgency. When this problem emerged repeatedly as a major management issue in the Emergency Room of The Johns Hopkins Hospital, we examined our experience and practices in order to propose reasonable guidelines to improve our handling of such patients.
Materials and Methods 37 consecutive patients who presented to the Emergency Room of The Johns Hopkins Hospital in Baltimore from September 1976 to March 1977 were enrolled in the study. All presented with com plaints of chest pain and shortness of breath and
had obvious chest wall disease, pneumonia, and coronary insufficiency excluded by physical exam ination, chest film, and ECG. Witnessed verbal and written informed consent for participation was obtained from each patient; none refused. The patients were interviewed for historical features and symptoms using questions directed toward the predisposing conditions listed in table I and the symptoms listed in table II. Whenever possible the interview data were confirmed by family members or the medical record. The ques tions were drawn from the Urokinase Pulmonary Embolism Trial, of which this institution was a part [3]. The study team representative then performed a focused physical examination in addition to that of the house officer attending the patient. The signs given in table II were noted and recorded with the results of the laboratory data itemized in table III. 13 patients were assigned to the ‘high probabil ity’ group, 8 on the basis of six-projection ventila-
Table I. Correlation of known predisposing factors with probability of pulmonary embolism
Total Male Female Lower extremity thrombophlebitis, active Chronic venous insufficiency Congestive heart failure Prolonged bed rest Chronic obstructive pulmonary disease Pulmonary embolism in past Pelvic disease or surgery Lower extremity trauma or surgery, > 6 months past Lower extremity trauma or surgery, < 6 months past Cancer, diagnosis known Estrogen medication Postpartum, < 6 months
High probability1
Low probability
n
n
13 7 6 62 52 43 3 33 3* 2 2 2 1 0 0
% 100 54 46 46 39 31 23 23 23 15 15 15 8 0 0
24 8 16 8 10 4 4 8 5 8 4 4 2 2 1
% 100 35 65 33 42 17 17 33 21 33 17 17 8 8 4
1 Classification on the basis of lung scan with or without pulmonary arteriogram in all but 2 cases (see below and text). 2 Includes 1 case in which classification made by right heart catheterization. 3 Includes the other case in which classification made by right heart catheterization.
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tion and perfusion lung scans interpreted as diag nostic or ‘high probability’ by our institution’s published criteria [4], 3 on the basis of suggestive lung scans confirmed by positive pulmonary arte riograms, and 2 on the basis of right heart cathe terization performed in the intensive care unit, both with recent histories of documented pulmonary emboli. These 13 patients constitute the popula tion we considered to be in the high probability category for having suffered pulmonary embolism. 24 patients were assigned to the ‘low probabili ty’ group, 22 on the basis of normal lung scans
and 2 on the basis of obvious alternative diagnos es, specifically the discovery after admission of early pneumonia and of metastatic carcinoma. These 24 patients constitute the population we considered to be in the low probability category for pulmonary embolism. The two groups were compared with each other and with previous re ports [3, 5-10J. The disposition of each patient was left to the discretion of the physician in attendance. The study representative did not intervene in manage ment decisions. Thus, the study represents the ac-
Table II. Presenting symptoms and signs on physical examination, correlated with probability group. (Chest pain and shortness of breath were criteria for inclusion into the study)
Symptoms Dyspnea, sudden onset Chest pain, vague substernal Chest pain, pleuritic Leg pain or cramping Hemoptysis Cough, sudden onset Signs Tachycardia ( > 100) Diaphoresis Rales, focal Thrombophlebitis, lower extremity Wheezing Accentuated pulmonic component of S2 Cyanosis Pleural rub Vital signs (mean ± SD) Pulse Temperature Respiratory rate Blood pressure, systolic Blood pressure, diastolic
High probability1
Low probability
n
%
n
%
113 73 6 5 4 2123
85 54 46 39 31 15
16 11 15 7 5 10
70 48 65 30 22 44
93 73 53 3 23 2 22 0
69 54 39 23 15 15 15 0
7 10 6 5 5 2 2 1
30 44 26 22 22 9 9 4
100.5 ± 37.1 ± 24.4 ± 138.9 ± 88.5 ±
16.3 0.9 6.1 35.4 23.8
92.7 ± 38.9 ± 22.3 ± 141.2 ± 86.8 ±
16.8 1.0 8.5 30.2 20.9
1 Classification on the basis of lung scan with or without pulmonary arteriogram in all but 2 cases (see below and text). 2 Includes 1 case in which classification made by right heart catheterization. 3 Includes the other case in which classification made by right heart catheterization.
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Finding
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Table III. Laboratory data correlated with probability of pulmonary embolism Laboratory test
High probability1
Low probability
n
n
%
%
Arterial blood gas tensions (mean ± SD) PaC>2 PaCOz pH Prothrombin time, % control Hematocrit, %
68.2 27.7 7.43 75 38.1
Chest films Atelectasis No abnormality Pleural effusion Infiltrate Cardiomegaly
53 4 2 2123 1
38 31 15 15 8
1 11 4 2 2
4 48 17 9 9
Electrocardiogram Nonspecific ST-T wave changes Peaked P wave in II Normal S in I, Q and T in III Clockwise rotation of axis New right bundle branch block New right axis deviation Right ventricular ‘strain’
73 42 3 22 2 2 1 I
54 31 23 15 15 15 8 8
8 1 10 2 2 0 0 0
35 4 44 9 9 0 0 0
± ± ± ± ±
14.1 5.0 0.04 25 5.8
69.3 31.0 7.46 77 40.8
± ± ± ± ±
13.9 7.2 0.05 21 5.7
tual practice at our institution and not a planned protocol. Patients who were admitted to the hospi tal were followed by the study team. Those who were not admitted were contacted by the study team by telephone in 1 week for follow-up infor mation.
Results A total of 37 patients were enrolled in the study, of whom 54% were women. Ages ranged from 18 to 76 with a mean of 49.0
years. Pulmonary embolism was judged probable in 13 patients, 46% of whom were women, with a mean age of 67.8 (range 56-71), and 54% men, with a mean age of 46.0 (range 25-65). 2 patients died in the high probability group, both within 3 days of admission with the clinical impression of recurrent massive embolism despite ade quate anticoagulation. Pulmonary embolism was judged not to be probable in 24 patients, 65% women, with an aggregate mean age of 45.7 (range
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1 Classification on the basis of lung scan with or without pulmonary arteriogram in all but 2 cases (see below and text). 2 Includes 1 case in which classification made by right heart catheterization. 3 Includes the other case in which classification made by right heart catheterization.
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Accuracy of Screening for Pulmonary Embolism in the Emergency Room
Table IV. Comparison of predisposing factors for pulmonary embolism (percent values) Characteristic
Sasahara el al., 1962 (6] Dalai el al., 1977 [8] n = 72» n = 41
Lower extremity thrombophlebitis Chronic venous insufficiency Prolonged recent bed rest Chronic obstructive pulmonary disease Past history of pulmonary embolism Congestive heart failure Pelvic disease or surgery Lower extremity manipulation, > 6 months previously Lower extremity manipulation. < 6 months previously Estrogenic medication Known cancer Postpartum, < 6 months
10 17 24
_
US Trials, 1977 [9) n = 327
~
40 15 8 8 26 17 6
~
3
_2
-
45 14 20
-
5 7 1
1 All but 1 patient were males. 2 In this report it is not clear from the text how many patients had preexisting congestive failure. 69% are reported to have had ‘heart disease’ in general, and 35% presented with symptoms mimicking congestive failure which were apparently related to their pulmonary embolism.
on physical examination are noted in table II. Laboratory data, including the chest film and ECG, are shown in table III.
Discussion One is immediately struck by how poorly the presence of putative predisposing fac tors is correlated with the ultimate judge ment of how likely it is that pulmonary em bolism has occurred. Although each is well documented in the literature [3, 5-9], none of the predisposing factors proved to be a reliable guide in this patient population, even when compared by sex. Pulmonary embolism appears to be pre dominantly a disease of older women and younger men in noninstitutionalized patients.
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18-76). There were no deaths in the low probability group. The leading alternative diagnosis in the low probability group was viral pleuritis (3), with chronic bronchitis (2), pericarditis, metastatic carcinoma, congestive heart failure, and pneumonia also seen. The remaining patients had no specific diagnosis confirmed; they were gen erally below the age of 35, women, and all did well. No patient was sent home from the Emergency Room who later became ill. The correlation between generally ac cepted predisposing conditions (comorbid states) and the eventual assignment into high and low probability groups for pul monary embolism is given in table I. Fur ther breakdown by sex did not reveal any specific trends different from the aggregate figures. The presenting symptoms and signs
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Table V. Comparison of data from various studies on signs, symptoms, and laboratory findings in pulmonary embolism (percent values). Characteristic
Gorham, 1961 [5] n = 1001
Sasahara e lal., Szucs el a/., Dalen et al., US Trials 1967 [6] 1967 (71 1977 [8] 1977 [9J n = 72 n = 50 n = 41 n = 327
Dyspnea, acute Chest pain, vague Chest pain, pleuritic Hemoptysis Cough, acute Tachycardia (> 100) Diaphoresis Rales, focal LE phlebitis Accentuated Pa Cyanosis Pleural rub
20 26 12
100
-
-
55 42 72 65
57 19
19 -
9
70 33 80 15 15
-
14 29 35 51
_
Electrocardiogram NS ST-T W J s 3 P-pulmonale in II SiQTiu ‘Clockwise’ rotation New RBBB New RAD Right vent, ‘strain’
Blood gases4 PaOa (torr) PaCOa (torr)
-
_
Chest film Normal Pleural effusion Infiltrate Abnormal, nonspecific
Vital signs4 Temperature Pulse Respiratory rate BP, systolic BP, diastolic
-
_ -
44
_
84 14 74 30 53 44 27 58 32 53 19 7 51 54
_
-
-
10
4 11 28 16 5
-
8 15
‘fever’ in 45 %5 >90 in 65% >20 in 65%
37.7 98.9 25.5 124.5 77.2 61 ± 29 37 ± 14
59.4 ±14.1 7.40 in 92%
1 Selected for fatal outcome. 2 Some results shown here have been recalculated from the published data. 3 Nonspecific ST-T wave changes. 4 Mean ± standard deviation. 5 ‘Fever’ not clearly defined.
>70 9 3 6 0 -
± ± ± ± ±
0.8 18.9 106 ± 4 8.8 20.8 13.3
61.2 ±14.2
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-
-
-
Ahonen, 1977 [10] n = 3512
The sex and age distribution of our popula tion with embolism judged probable was similar to that of the Urokinase-Strep tokinase Pulmonary Embolism Trials [9]. The relatively low mortality from treat ed embolism in our study is in keeping with previous reports [1]. Our patients had a high frequency of lower extremity venous disease in the high probability group, but so did an unexpected ly large number of patients in the low prob ability group, especially women (44°/o). Our high probability group was more likely to have had congestive heart failure, pelvic disease, and chronic venous insufficiency than the group with embolism diagnosed in the Trials, and was less likely to have had re cent immobilization or oral contraceptives; they were as likely to have had a malignan cy. By comparison, our embolism low prob ability group matched or exceeded the fre quency of predisposing factors in the high probability group except for bed rest and congestive failure. The most probable ex planation, assuming that these comorbid states are truly predisposing (and evidence from the Trials suggests that perhaps recent termination of pregnancy is not) [9], is that our study population has such a high prev alence of these medical problems that the history did not serve as a useful discrimi nant in individual cases. Presenting signs and symptoms were lit tle better. None of the cardinal findings of pulmonary embolism reliably suggested the diagnosis, nor did their absence reliably ex clude it. Table V presents the comparable data for similar, larger published studies, in cluding the Trials [9] and that of Sasahara et al. [6], Our high probability population had as frequent dyspnea and hemoptysis, less frequent chest pain (and less often pleu
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ritic) and cough than the patients with em bolism diagnosed in the Trials. Again, the distribution of these symptoms in our low probability group is remarkably similar to our high probability group and also to the Trials. The physical findings in our high probability group are more generally consis tent with the findings of the Trials. Our pa tients had tachycardia and diaphoresis more often than the patients with embolism con firmed in the Trials, and focal rales, active thrombophlebitis, and accentuation of the pulmonic component of the second heart sound less often than the patients in the Trials and much less often than the patients in whom pulmonary embolism was diag nosed in Sasahara et al. [6] Cyanosis was present equally in both groups.The high prob ability group patients also had these findings more often than the low probability group patients. Despite these group differences, the vital signs were not statistically different between them, raising questions as to the usefulness of fever, tachypnea, and tachy cardia in implying the diagnosis. It should also be noted that fever, pleuritic chest pain, and cough may be features of a viral pleuritis. one of the leading alternative diagnoses. Laboratory data customarily obtained in our Emergency Room contributed little. The blood gases were of limited value; the mean Pao2 was surprisingly low in the low probability group, suggesting that the diag nostic dilemma occurs regularly in patients with intrinsic lung disease. The mean Pao2 and standard deviation for patients with confirmed pulmonary embolism have been remarkably reproducible between studies, but hypoxemia remains a nonspecific find ing in the individual patient. The hematocrit and prothrombin time were of no help, al though detection of polycythemia or a coa
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Accuracy of Screening for Pulmonary Embolism in the Emergency Room
gulopathy might have been clinically useful had either been present in a patient. The chest film was of little use in assign ing the patients to probability groups. Again, this is probably because the diagnos tic dilemma arises often in patients with es tablished pulmonary or cardiovascular dis ease. Patients in whom the diagnosis was ul timately judged probable tended to have more abnormalities in general, particularly discoid atelectasis, but this was not helpful in managing the individual patient. Almost one third of the patients in the high proba bility group had normal chest films. The ECG was somewhat, but not much, more helpful. More patients in the high probability group had an abnormal ECG, and the specific abnormalities were those of right ventricular and right atrial disturbance (or ‘strain’). Inevitable questions ob bias must be ad dressed in this study. The population is small compared to those of the multicenter studies, but compatible with our intent to examine clinical practice in a nonidealized sample. From a clinician’s standpoint, there is a practical limit to the utility of large mul ticenter studies. Although these are enor mously valuable in advancing our under standing of the pathophysiology and incid ence of the disease, clinical findings and dis tinctions which require huge numbers of pa tients to document are not very helpful in practice. We have relied upon lung scanning in assigning most of our patients to high and low probability categories. This is an accur ate reflection of clinical practice at this in stitution, where the statistical limitations of the technique have been described in detail compared to pulmonary arteriography [4], Clearly, an error rate even twice that docu mented for this institution would not sub
Guidotti/Fries/Bcll/Gurley/Pachner
stantially alter the trends (or lack thereof) that we have observed. Furthermore, the in tent of this study was not to assess the utility of historical, clinical, and laboratory find ings in confirming the diagnosis of pulmon ary embolism, but rather to identify factors which might, singly or in combination, sug gest that the patient be assigned to a high probability category which should be inves tigated further as an inpatient. In an age where restrictions are placed on the expansion of clinical facilities, medi cal wards are subject to fluctuating census, and cost containment is a major issue, ad missions which do not lead to a useful inter vention should be avoided. We have shown that the usual historical, clinical, and labo ratory findings associated with pulmonary embolism are not reliable to screen patients for admission. The overriding consideration of patient welfare therefore requires that a relatively high frequency of admissions for patients in whom embolism is ultimately ruled out must be tolerated, so that virtually all of those with the disease will be treated. The partial answer to this trade-off may be to increase the availability of outpatient lung scans, specifically six-projection ven tilation-perfusion scans with access directly from the emergency room on an urgent ba sis [11, 12]. This is a costly alternative, however, requiring access to a facility which is already much in demand. Nonetheless, it is clear that the diagnosis of pulmonary em bolism can be screened in no other way, and that patients cannot be assigned to high and low probability groups for the diagnosis by the usual laboratory and clinical findings available in the emergency room. We remain strong believers in the value of a comprehensive evaluation and educated clinical judgement. Nonetheless, we are
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Accuracy of Screening for Pulmonary Embolism in the Emergency Room
Acknowledgement We are grateful to the housestaff on the Osier service of The Johns Hopkins Hospital, whose cooperation, interest, and tradition of independent investigation made this study possible.
References 1 Alperts, J. S., et al.: Mortality in patients treated for pulmonary embolism. J. Am. mcd. Ass. 236: 1477-1480 (1976). 2 Sutton, G. C.: Clinical course and late progno sis of treated subacute massive, acute minor, and chronic pulmonary thromboembolism. Br. Heart J. 39: 1135-1142 (1977). 3 Urokinase Pulmonary Embolism Study Group: Urokinase pulmonary embolism trial. Circula tion 49: suppl. 2 (1974). 4 Poulose, K. P., et al.: Diagnosis of pulmonary embolism. Br. med. J. iii: 67-71 (1970). 5 Gorham, L. W.: A study of pulmonary embo lism. Archs intern. Med. 108: 76-97 (1961). 6 Sasahara, A. A., et al.: Clinical and physiolog ic studies in pulmonary thromboembolism. Am. J. Cardiol. 20: 10-20 (1967).
7 Szucs, M. M., et al.: Diagnostic sensitivity of laboratory findings in acute pulmonary embo lism. Ann. intern. Med. 74: 161-166 (1971). 8 Dalen, J. E., et al.: Pulmonary embolism, pul monary hemorrhage and pulmonary infarction. New Engl. J. Med. 296: 1431-1435 (1977). 9 Bell, W. R., Simon, T. L., and DeMets, D. L.: The clinical features of submassive and mas sive pulmonary emboli. Am. J. Med. 62: 355-360 (1977). 10 Ahonen, A.: Electrocardiographic changes in massive pulmonary embolism. I. Analysis of the changes in P wave and QRS complex. II. Analysis of the changes in ST segments and T wave. Acta med. scand. 201: 539-542, 543-545 (1977). 11 Moser, K. M., et al.: Differentiation of pul monary vascular from parenchymal diseases by ventilation: perfusion scintigraphy. Ann. in tern. Med. 75: 597-605 (1971). 12 Bell, W. R. and Simon, T. L.: A comparative analysis of pulmonary perfusion scans with pulmonary angiograms. Am. H eart J. 92: 700-706 (1976).
Received: June 13, 1978 Accepted: September 29, 1978 William R. Bell, MD, The Johns Hopkins Hospital, 601 N. Broadway, Baltimore, MD 21205 (USA)
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forced to conclude that at the present state of the art screening for pulmonary embo lism rests solely on a diagnostic procedure.
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