Correspondence.

(Letters to the Editor are welcomed. They may report new clinical or laboratory observations and new developments in medical care or may contain Comments on recent contents of the Journal. They will be published, if found suitable, as space permits. Like other material submitted for publication, letters must be typewritten, double-spaced, and submitted in duplicate. They

must not exceed two typewritten pages in length. No more than five references and one figure or table may be used. See "Information for Authors" for format of references, tables, and figures. Editing, possible abridgment, and acceptance remain the prerogative of the Editors.)

Importance of Individualized Decision in the Management of Massive Pulmonary Embolism

To the Editor: It is important for the treating clinician to make a clear judgment of risk versus benefit in management of each patient having pulmonary embolism (PE).

Case Report. A 58-year-old woman had staging surgery for ovarian cancer. During the operation, her arterial oxygen saturation transiently dropped. A V/Q scan immediately after the operation revealed large perfusion defects. The patient was hemodynamically stable and oxygenation was maintained with supplemental oxygen. Because of fear of bleeding, she was given low molecular weight heparin subcutaneously. A duplex venous scan showed thrombosis in the left femoral vein. While inferior vena caval filter placement was being arranged, the patient went into shock but was successfully resuscitated and her blood pressure was maintained with pressors. At this point, the patient was fully heparinized intravenously but thrombolytic therapy was rejected again for fear of bleeding. During attempts to arrange for embolectomy, the patient developed pulseless electrical activity and could not be resuscitated. An autopsy revealed a fresh large embolus and several other emboli of different stages.

Discussion. In this case, the correct diagnosis of PE was established early and several life-saving measures were considered. However, aggressive action was not undertaken. The case represents a common scenario in PE management when there is a reasonable fear of bleeding while the patient continues to be at risk for recurrent PE. Under such circumstances, the decision for intervention is often driven by deterioration of the clinical condition and is often too late. Until now, the guideline for thrombolysis in massive PE remains much less conclusive than anticoagulation in venous thromboembolism (VTE). (1-3) Thus, in the management of massive PE, it is important for the physician to realize that the severity is fundamentally distinct from general VTE and gauge the aggressiveness based on the clinical scenario.

Massive PE is not defined only by occlusion area. (1-4) In patients with cardiopulmonary compromises, a small PE can cause sudden elevation of pulmonary arterial pressure, rapidly leading to right ventricular dysfunction (RVD) and failure, shock, and death. (3-5) Thus, the defining features of massive PE are these fatal hemodynamic consequences. Of them, RVD is the most important since it is the earliest sign of poor prognosis. (3)

Mechanical obstruction from massive PE causes RVD accompanied by a decrease in systemic blood pressure. (4-5) The mechanism of hypotension is related to sudden expansion in the right ventricle (RV). Echocardiographic studies in patients with massive PE have documented RV chamber dilation. (3) the dilated RV displaces the interventricular septum toward the left ventricle (LV) and thereby reduces LV volume. When massive PE is successfully thrombolysed, RV chamber size returns to normal and compression of the LV is released. (3)

The principles for management of massive PE are to rapidly release the obstruction to RV outflow and reverse RV failure. Shock should be aggressively controlled with pressor resuscitation to maintain perfusion in the right coronary artery. (3-4) Fluid management should be done with caution because in acute RV failure due to outflow obstruction, volume expansion may further dilate the RV and actually reduce the cardiac output. (4-5)

Thrombolysis is effective in release of obstruction in RV outflow and can be administered immediately. (1-3) When risk of bleeding is high, a short-acting agent may be preferable. Alternative approaches to release obstruction by PE are limited. Surgical embolectomy is associated with high mortality. Recently, fragmentation of the embolus using a catheter technique is being developed. Following embolectomy, the patient still needs prophylaxis for recurrent PE.

If the patients with massive PE cannot be stabilized, even absolute contraindications to thrombolysis may have to be neglected, since the patients are otherwise facing death. We encountered two more cases of massive PE after the index case was discussed in a grand round. The first patient was a 58-year-old woman who had resection of a meningioma. Ten days later, massive PE developed. Heparinization and aggressive pressor support were insufficient to stabilize her blood pressure. The second case was a 72-year-old woman who had been treated for bleeding esophageal varices. Two weeks later, she had a massive PE and her blood pressure was barely maintained on pressors. Both of these patients received thrombolytic therapy and both were successfully resuscitated. In both of these cases, strong contraindications existed for thrombolytic therapy, yet the treatment turned out to be life-saving.

In summary, the pathophysiology and management of massive pulmonary embolism are significantly different from those of general VTE. Right ventricular dilation and shock are early and late signs of high mortality. In these situations, thrombolysis should be considered even in the face of concerns about bleeding. Since there has not been a definite guideline for thrombolysis for massive PE, (1-2) a clear judgment of risk versus benefit by the treating clinician is important in the management of the individual patient.

Renli Qiao, MD, PhD

Thomas E. Addison, MD

Division of Pulmonary and Critical Care Medicine

Keck School of Medicine

University of Southern California

2025 Zonal Aye, GNH 11900

Los Angeles, CA 90033

References

(1.) Arcasoy SM, Kreit JW: Thrombolytic therapy of pulmonary embolism. Chest 1999; 115:1695-1707

(2.) Hyers TM, Agnelli G, Hull RD, et al: Antithrombotic therapy for venous thromboembolic disease. Chest 2001; 119:176S-193S

(3.) Goldhaber SZ: Pulmonary embolism. N Engl J Med 1998; 339:93-104

(4.) Tapson VF, Witty LA: Massive PE. Clin Chest Med 1995; 16:329-340

(5.) Elliott CG: Pulmonary physiology during PE. Chest 1992; 101:163S-171S

A "Hospitalist" Rotation Increases Short-term Knowledge of Fourth-Year Medical Students

To the Editor: Written examinations remain an important objective tool in measuring basic and clinical knowledge acquisition of medical students. While other parameters are also important in assessing clinical performance, multiple-choice testing remains an objective, practical modality. This study was performed to assess medical students' performance on a 20-question test of general inpatient internal medicine before and after a fourth-year elective "hospitalist" rotation.

Over a 2-academic-year period, 12 fourth-year medical students enrolled in an inpatient internal medicine hospitalist rotation with me at Miami Valley Hospital, a major affiliate of Wright State University School of Medicine in Dayton, Ohio, were administered a 20-question multiple choice test on the first day of the rotation. The questions covered a variety of common clinical topics encountered in hospital medicine. The students were given approximately 30 minutes to complete the questions, and were not permitted to use any references. The test was collected and the answers were not revealed. The same examination was administered in a similar manner on the last day of the rotation, after which the results of each test were shared with the students. All but one student (92%) increased their score on the second examination. The mean ([+ or -] standard deviation) number of correct answers was 12.58 [+ or -] 2.35 on the initial test and 15.33 [+ or -] 2.71 on the final test (mean difference 2.75; P < .001 via p aired t-test).

Other investigators have shown that multiple choice testing is a simple device for measuring short-term knowledge acquisition among residents and medical students during a 1-month clinical rotation in infectious diseases.' This present study reinforces the idea that medical students can increase their short-term knowledge during a 1month clinical rotation when measured by multiple choice testing. Students were exposed to a variety of patients and clinical scenarios during the rotation. In addition, the students were directed to read articles related to their patients, as well as various articles on common hospital medicine topics. While some students' scores may have been higher due to encounters with patients who had problems that were covered by the test, it seems that a 1month hospitalist rotation improves short-term knowledge in general inpatient medicine principles.

Acknowledgment. I thank Ronald J. Markert, PhD, for assistance with the statistical analysis.

Mark A. Marinella, MD

Wright State University School of Medicine

33 W Rahn Rd, #201

Dayton, OH 45429

Reference

(1.) Czachor JS, Hawley HB, Markert RJ, et al: Knowledge acquisition in a one-month infectious diseases rotation. Acad Med 1998; 73:1214