Clinical study
Use of pulse oximetry to predict in-hospital complications in normotensive patients with pulmonary embolism

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Abstract

Purpose

A simple method is needed to risk stratify normotensive patients with pulmonary embolism. We studied whether bedside clinical data can predict in-hospital complications from pulmonary embolism.

Methods

We performed a multicenter derivation phase, followed by validation in a single center. All patients were normotensive; the diagnosis of pulmonary embolism was established by objective imaging. Classification and regression analysis was performed to derive a decision tree from 27 parameters recorded from 207 patients. The validation study was conducted on a separate group of 96 patients to determine the derived criterion's diagnostic accuracy for in-hospital complications (cardiogenic shock, respiratory failure, or death).

Results

Mortality in the derivation phase was 4% (n = 8) at 24 hours and 10% (n = 21) at 30 days. A room-air pulse oximetry reading <95% was the most important predictor of death; mortality was 2% (95% confidence interval [CI]: 0% to 6%) in patients with pulse oximetry ≥95% versus 20% (95% CI: 12% to 29%) with pulse oximetry <95%. In the validation phase, the room-air pulse oximetry was <95% at the time of diagnosis in 9 of 10 patients who developed an in-hospital complication (sensitivity, 90%) and ≥95% in 55 of 86 patients without complications (specificity, 64%).

Conclusion

Mortality from pulmonary embolism in normotensive patients is high. A room-air pulse oximetry reading ≥95% at diagnosis is associated with a significantly lower probability of in-hospital complications from pulmonary embolism.

Section snippets

Derivation study

Data were collected prospectively in two phases: a derivation and validation phase. The derivation phase was conducted in emergency departments at seven urban teaching hospitals in the United States. This study was reviewed and approved by the Institutional Review Board for research on human subjects at all institutions. Patients were enrolled in the study when a board-certified emergency department physician ordered a pulmonary vascular imaging study (either a contrast-enhanced computerized

Derivation phase

The derivation set consisted of a sample of 1195 emergency department patients evaluated for pulmonary embolism, of whom 212 (18%) were diagnosed with pulmonary embolism (Table 1). We excluded 5 patients with pulmonary embolism (fibrinolytic agent given in the emergency department [n = 1], no treatment given [n = 3], vasopressor treatment for hypotension after enrollment but before diagnosis [n = 1]). Of the remaining 207 patients, 21 (10%) died during the subsequent 30 days, at a median of

Discussion

Among 303 normotensive patients with pulmonary embolism treated initially with heparin anticoagulation, we observed an in-hospital mortality rate of 10%, which agrees with previous results in similar patients (4, 5, 17). In our study, 4% of nonhypotensive patients with pulmonary embolism died within 24 hours of diagnosis. None of these patients had malignancy or advanced cardiopulmonary disease. These data suggest the value of an accurate method to recognize patients at risk of short-term

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  • Cited by (0)

    This study was supported by the Emergency Medicine Foundation, Irving, Texas.

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