Predictive tools help identify which pulmonary embolism patients need ICU admission

The best predictors of in-hospital deterioration of patients diagnosed with acute pulmonary embolism in the emergency department are a shock index greater than 1 and a pulmonary embolism severity index score more than 100, according to data from the EMPEROR registry.

The clinical implications: Calculate the pulmonary embolism severity index (PESI) and shock index routinely in patients with pulmonary embolism. And strongly consider admission to an ICU for those patients having values above the thresholds, Dr. Jeffrey A. Kline said at the annual meeting of the Society for Academic Emergency Medicine.

He analyzed the prognostic accuracy of five predictors of in-hospital adverse events in 2,188 consecutive patients diagnosed with pulmonary embolism in 22 EDs participating in the landmark EMPEROR (Emergency Medicine Pulmonary Embolism in the Real World Registry) study, the first-ever large multicenter prospective observational study of pulmonary embolism in the United States.

The goal was to identify tools that will help emergency physicians decide whether to admit patients with pulmonary embolism to the ICU, a regular ward, or a telemetry bed, explained Dr. Kline, director of research in the department of emergency medicine at Carolinas Medical Center, Charlotte, N.C.

Five predictors were selected for study inclusion based upon the medical literature and widespread round-the-clock availability in U.S. EDs. The predictors were an oxygen saturation (SaO2) below 95%, an abnormal serum troponin level, a brain natriuretic peptide level greater than 90 pg/mL or pro-brain natriuretic peptide level in excess of 900 pg/mL, a shock index greater than 1, and a PESI score greater than 100 (see Figure).

The shock index is obtained by dividing heart rate by systolic blood pressure. The PESI score, also known as the Aujesky prognostic model, was developed by a team led by Dr. Drahomir Aujesky of the University of Lausanne, Switzerland. It incorporates 11 simple patient factors shown to be independently associated with 30-day mortality in more than 15,000 pulmonary embolism patients.

Those factors include age greater than 65 years, male sex, and comorbid cancer, chronic pulmonary disease, or heart failure. Also, a systolic blood pressure less than 100 mm Hg, altered mental status, a respiratory rate of 30 per minute or more, heart rate of 110 bpm or more, temperature less than 36° C, and an SaO2 of less than 90% (Am. J. Respir. Crit. Care Med. 2005;172:1,041-6).

The composite in-hospital adverse outcome measure used in EMPEROR consisted of death from pulmonary embolism, shock requiring vasopressors, intubation, or surgical embolectomy. It occurred in 3.5% of patients. Nearly all adverse events happened within 48 hours; roughly two-thirds occurred within 24 hours.

Interestingly, Dr. Kline said, death from pulmonary embolism occurred in only 0.9% of EMPEROR participants. “That’s in striking contrast to European data suggesting up to about 10% in-hospital mortality,” he observed.

None of the predictors displayed good sensitivity for predicting adverse events. However, a PESI greater than 100 had outstanding specificity and conferred an 8.7-fold increased likelihood of adverse outcome. The shock index performed second best. The two vital signs proved to be slightly better predictors than the two biomarkers.

An upgrade to the ICU occurred in 1.5% of patients within 24 hours after their admission to a telemetry or regular hospital bed. “So, we do a pretty good job: 98.5% of our patients do not get an upgrade to an ICU,” Dr. Kline commented.

Audience members said they are under pressure from hospital administrators to identify patients with pulmonary embolism who can safely be discharged home. They asked whether any of the five predictors were useful for that purpose.

Dr. Kline replied that he hasn’t looked at the EMPEROR data toward that end. However, he is aware of ongoing European studies that suggest a PESI score lower than 50 or so shows potential for such a purpose.