Use of helical CT is associated with an increased incidence of postoperative pulmonary emboli in cancer patients with no change in the number of fatal pulmonary emboli

Abstract

Background: Multidetector computed tomography (MDCT) scanning technology has increased the ease with which pulmonary emboli (PE) are evaluated. Our aim was to determine whether the incidence and severity of postoperative PE have changed since adoption of multidetector computed tomography.

Study design: A prospective postoperative morbidity and mortality database from a single institution was used to identify all cancer patients who experienced a PE within 30 days of thoracic, abdominal, or pelvic operations. The incidence, type (central, segmental, and subsegmental), and severity of PE were examined.

Results: A total of 295 PE were documented among 47,601 postoperative cancer patients. The incidence of PE increased yearly from 2.3 per 1,000 patients in 2000 to 9.3 per 1,000 patients in 2005 (p < 0.0001). This corresponded to an increasing number of CT scans of the chest performed (6.6 CT scans per 1,000 postoperative patients in 2000 versus 45 in 2005; p < 0.0001). The increased incidence was because of a 7.8% (CI, 4.0 to 11.7) and 5.4% (CI, 4.1 to 6.7) average annual increase in segmental and subsegmental PE, respectively. There was no change in the number of central (0.1%; CI, -1.0 to 1.12) PE. Overall incidence of fatal PE was 0.4 and did not change during the time period (p = 0.3). A central PE was more commonly associated with hypoxia, ICU admission, and 30-day mortality (33% versus 5% for peripheral; p = 0.02).

Conclusions: Chest CT scans are being performed more frequently on postoperative cancer patients and have resulted in an increased diagnosis of peripheral PE. The clinical significance of, and optimal treatment for, diagnosed subsegmental PE are incompletely defined.

Figure 1

Annual postoperative incidence of multidetector computed tomography (MDCT) scan of the chest, pulmonary embolism (PE), and fatal PE. The number (incidence per 1,000 postoperative patients) of MDCT of the chest performed to evaluate patients for a PE in the postoperative period (black bar) and the number of postoperative PEs (gray bar) detected have increased from 2000 to 2005, while the incidence of a fatal PE among surgical patients in the postoperative period has remained unchanged (white bar).

Figure 2

Annual incidence of central (diamond) and peripheral (segmental [square] and subsegmental [triangle]) pulmonary embolism during the 2000–2005 study periods.

Figure 3

Clinical symptoms and signs among patients with a postoperative pulmonary embolism (PE) by surgery year and central versus peripheral location in the pulmonary vasculature. (Clinical findings include shortness of breath, chest pain, tachycardia, hypoxia, clinical evidence of deep vein thrombosis, or hemoptysis.) PE, pulmonary embolism.

Figure 4

Kaplan-Meier survival curves among patients with postoperative central versus peripheral pulmonary embolism (PE). (A) Thirty-day mortality among cancer patients who were found to have a central PE (n = 33) was significantly worse compared with those who were found to have a peripheral PE (n = 237). (B) The median survival among cancer patients with a postoperative central PE was 7.1 months compared with 57.6 months among cancer patients with a postoperative peripheral PE (p = 0.003).