Point-of-care ultrasonography in patients admitted with respiratory symptoms: a single-blind, randomised controlled trial

Summary

Background

When used with standard diagnostic testing, point-of-care ultrasonography might improve the proportion of patients admitted with respiratory symptoms who are correctly diagnosed 4 h after admission to the emergency department. We therefore assessed point-of-care ultrasonography of the heart, lungs, and deep veins in addition to the usual initial diagnostic testing in this patient population.

Methods

In a prospective, parallel-group trial in the emergency department at Odense University Hospital, Odense, Denmark, patients (≥18 years) with a respiratory rate of more than 20 per min, oxygen saturation of less than 95%, oxygen therapy, dyspnoea, cough, or chest pain were randomly assigned in a 1:1 ratio with a computer-generated list to a standard diagnostic strategy (control group) or to standard diagnostic tests supplemented with point-of-care ultrasonography of the heart, lungs, and deep veins (point-of-care ultrasonography group). The primary endpoint was the percentage of patients with a correct presumptive diagnosis 4 h after admission to the emergency department. Only the physicians doing the primary clinical assessment and the auditors were masked. Analyses were by intention to treat. The study is registered with ClinicalTrials.gov, number NCT01486394.

Findings

Between Dec 7, 2011, and March 15, 2013, 320 patients were randomly assigned to the control group (n=160) and point-of-care ultrasonography group (n=160). 158 patients in the point-of-care ultrasonography group and 157 in the control group were analysed. 4 h after admission to the emergency department, 139 patients (88·0%; 95% CI 82·8–93·1) in the point-of-care ultrasonography group versus 100 (63·7%; 56·1–71·3) in the control group had correct presumptive diagnoses (p<0·0001). The absolute and relative effects were 24·3% (95% CI 15·0–33·1) and 1·38 (1·01–1·31), respectively. No adverse events were reported.

Interpretation

Point-of-care ultrasonography is a feasible, radiation free, diagnostic test, which alongside standard diagnostic tests is superior to standard diagnostic tests alone for establishing a correct diagnosis within 4 h. It should therefore be considered for routine use as part of the standard diagnostic tests in the emergency department for patients admitted with respiratory symptoms.

Funding

University of Southern Denmark, Odense University Hospital, and Højbjerg Fund.

Introduction

Patients with respiratory symptoms constitute a large proportion of all admissions to the emergency department.¹ Often these symptoms are caused by common diseases such as heart failure, pneumonia, chronic obstructive pulmonary disease (COPD), and pulmonary embolism.² A substantial proportion of these patients are given an incorrect diagnosis and inappropriate treatment in the emergency department according to the results of several studies, which raises questions about the diagnostic accuracy of clinical examinations and initial diagnostic tests in patients with respiratory symptoms.2, 3, 4, 5, 6, 7 Incorrect diagnosis and inappropriate treatment in the emergency department increase the number of deaths and length of hospital stay.² Results of several studies have shown that sonographic examinations have excellent diagnostic accuracy for the diseases most commonly encountered in patients admitted with respiratory symptoms.7, 8, 9, 10, 11, 12, 13, 14, 15 These diseases most often involve the heart, lungs, or deep veins of the legs, all of which can be directly visualised with sonography.² The idea of using point-of-care ultrasonography as an ultrasound stethoscope is rapidly becoming integrated into clinical practice and medical education.¹⁶ Several emergency medicine societies have developed guidelines for the use of ultrasound in an emergency department setting, but there are few studies assessing the use of point-of-care ultrasonography in emergency departments either nationally and internationally.17, 18, 19 The results of a study in France showed that point-of-care ultrasonography was available in about half of emergency departments.²⁰ Point-of-care ultrasonography was most commonly used for assessment of trauma patients.²⁰ Despite being a rapidly evolving diagnostic test in the emergency department, knowledge is needed about whether point-of-care ultrasonography actually increases the proportion of patients who are correctly diagnosed and treated in the emergency department. Aside from improving the health care of individuals, improved diagnostic assessment with point-of-care ultrasonography might also have a positive effect at a societal level (by reducing health-care costs and morbidity and mortality rates), because respiratory and cardiac diseases are all major public health problems.21, 22, 23, 24

In a descriptive pilot study done before this trial, use of point-of-care ultrasonography enabled identification of life-threatening illnesses that had been missed.⁷ Consequently, in this study, we investigated the null hypothesis that point-of-care ultrasonography of the heart, lungs, and deep veins in addition to usual initial diagnostic tests does not increase the percentage of patients admitted with respiratory symptoms who receive a correct presumptive diagnosis within 4 h after admission to the emergency department compared with the current diagnostic methods. A period of 4 h was chosen because according to the regional hospital guidelines patients admitted to an emergency department are expected to have a presumptive diagnosis within 4 h of admission.²⁵ This 4 h target for quality of care and resource use in the emergency department has been adapted from what has been implemented throughout the UK.²⁶