[Diagnosis of pulmonary embolism]

PERC rule to exclude the diagnosis of pulmonary embolism in emergency low-risk patients: study protocol for the PROPER randomized controlled study

BACKGROUND

The diagnosis of Pulmonary Embolism (PE) in the emergency department (ED) is crucial. As emergency physicians fear missing this potential life-threatening condition, PE tends to be over-investigated, exposing patients to unnecessary risks and uncertain benefit in terms of outcome. The Pulmonary Embolism Rule-out Criteria (PERC) is an eight-item block of clinical criteria that can identify patients who can safely be discharged from the ED without further investigation for PE. The endorsement of this rule could markedly reduce the number of irradiative imaging studies, ED length of stay, and rate of adverse events resulting from both diagnostic and therapeutic interventions. Several retrospective and prospective studies have shown the safety and benefits of the PERC rule for PE diagnosis in low-risk patients, but the validity of this rule is still controversial. We hypothesize that in European patients with a low gestalt clinical probability and who are PERC-negative, PE can be safely ruled out and the patient discharged without further testing.

METHODS/DESIGN

This is a controlled, cluster randomized trial, in 15 centers in France. Each center will be randomized for the sequence of intervention periods: a 6-month intervention period (PERC-based strategy) followed by a 6-month control period (usual care), or in reverse order, with 2 months of "wash-out" between the 2 periods. Adult patients presenting to the ED with a suspicion of PE and a low pre test probability estimated by clinical gestalt will be eligible. The primary outcome is the percentage of failure resulting from the diagnostic strategy, defined as diagnosed venous thromboembolic events at 3-month follow-up, among patients for whom PE has been initially ruled out.

DISCUSSION

The PERC rule has the potential to decrease the number of irradiative imaging studies in the ED, and is reported to be safe. However, no randomized study has ever validated the safety of PERC. Furthermore, some studies have challenged the safety of a PERC-based strategy to rule-out PE, especially in Europe where the prevalence of PE diagnosed in the ED is high. The PROPER study should provide high-quality evidence to settle this issue. If it confirms the safety of the PERC rule, physicians will be able to reduce the number of investigations, associated subsequent adverse events, costs, and ED length of stay for patients with a low clinical probability of PE.

TRIAL REGISTRATION

NCT02375919 .

Pulmonary Embolism in the Mechanically-Ventilated Critically Ill Patient: Is it Different?

Pulmonary embolism (PE) confers significant in-hospital morbidity and mortality, and critically ill patients remain at risk for venous thromboembolism despite thromboprophylaxis. Recognition of the clinical manifestations and immediate management of PE are of paramount importance. Despite diagnostic advances, PE is often undiagnosed and untreated in patients receiving mechanical ventilation, as these patients do not exhibit the common clinical features of the condition, making the diagnosis very challenging. Computed tomographic pulmonary angiography is probably the reference standard for the diagnosis of acute PE in the haemodynamically stable, ventilated patient. In the setting of circulatory collapse, bedside echocardiography may be used to risk stratify these patients, based on the presence or absence of right ventricular dysfunction, and guide further management. Treatment options include anticoagulation alone, anticoagulation plus thrombolysis, surgical or catheter embolectomy. Inotropes, vasopressors and pulmonary artery vasodilators may be considered after initial resuscitation of the right ventricle. Few studies have focused on estimating the prevalence of PE among mechanically-ventilated intensive care unit (ICU) patients and there is notable lack of data assessing predictive factors, prevention, diagnostic strategy and management of PE in the ICU setting.