Chapter 59: Pulmonary Embolism

PATIENT STORY

A 52-year-old woman developed acute shortness of breath 3 weeks after a hysterectomy. She denied leg pain or swelling. She has no chronic medical problems and takes no medications. Her pulse is 105 beats/min, respiratory rate is 20 breaths/min, and the rest of her examination is unremarkable. She had an elevated hemidiaphragm on chest X-ray (CXR). These findings placed her at moderate risk for pulmonary embolism (PE) based on the Geneva score. Chest CT demonstrated a moderate-sized PE like the one shown in Figure 59-1. She was treated with anticoagulation without complications.

INTRODUCTION

PE is a thromboembolic occlusion (total or partial) of one or more pulmonary arteries, usually arising from venous thromboembolism (VTE).

SYNONYMS

PE is also known as pulmonary thromboembolism and VTE as deep venous thrombosis (DVT).

EPIDEMIOLOGY

• In a report based on national surveillance data from 2007 to 2009, the estimated mean annual incidence of hospitalization with VTE in adults in the United States was 547,596. PE is diagnosed in an estimated mean 277,549 annual hospitalizations.¹

• In one population-based retrospective medical record review from Olmstead County, Minnesota, the average annual incidence of in-hospital VTE was 960.5 per 10,000 person years, more than 100 times greater than that among community residents.² PE accounted for most of the age-related increase among hospital cases.

• Authors of one meta-analysis concluded that nearly 1 in every 4 to 5 patients presenting with an exacerbation of chronic obstructive pulmonary disease has a PE; presenting signs and symptoms did not distinguish patients with and without PE.³

• In a meta-analysis of randomized controlled trials (RCTs) of patients on VTE prophylaxis, the pooled rates of symptomatic DVT were 0.63% (95% confidence interval [CI], 0.47% to 0.78%) following knee arthroplasty and 0.26% (95% CI, 0.14% to 0.37%) following hip arthroplasty. The pooled rates for PE were 0.27% (95% CI, 0.16% to 0.38%) following knee arthroplasty and 0.14% (95% CI, 0.07% to 0.21%) following hip arthroplasty.⁴

• Authors of a meta-analysis of 12 studies concluded that PEs were noted as incidental findings in 2.6% (95% CI 1.9, 3.4) of chest CT studies.⁵

ETIOLOGY AND PATHOPHYSIOLOGY

• PE is most commonly caused by embolization of a thrombus from a proximal leg or pelvic vein that enters the pulmonary artery circulation and obstructs a vessel. PE may also be caused by an upper-extremity thrombus (Figure 59-1); fat embolus; ...