Evaluation of lung ultrasound for the diagnosis of pneumonia in the ED

doi:10.1016/j.ajem.2008.03.009

The American Journal of Emergency Medicine

Volume 27, Issue 4, May 2009, Pages 379-384

https://doi.org/10.1016/j.ajem.2008.03.009 Get rights and content

Abstract

Objectives

The aim of this study is to assess the ability of bedside lung ultrasound (US) to confirm clinical suspicion of pneumonia and the feasibility of its integration in common emergency department (ED) clinical practice.

Methods

In this study we performed lung US in adult patients admitted in our ED with a suspected pneumonia.

Subsequently, a chest radiograph (CXR) was carried out for each patient. A thoracic computed tomographic (CT) scan was made in patients with a positive lung US and a negative CXR. In patients with confirmed pneumonia, we performed a follow-up after 10 days to evaluate clinical conditions after antibiotic therapy.

Results

We studied 49 patients: pneumonia was confirmed in 32 cases (65.3%). In this group we had 31 (96.9%) positive lung US and 24 (75%) positive CXR. In 8 (25%) cases, lung US was positive with a negative CXR. In this group, CT scan always confirmed the US results. In one case, US was negative and CXR positive. Follow-up turned out to be always consistent with the diagnosis.

Conclusion

Considering that lung US is a bedside, reliable, rapid, and noninvasive technique, these results suggest it could have a significant role in the diagnostic workup of pneumonia in the ED, even if no sensitivity nor specificity can be inferred from this study because the real gold standard is CT, which could not be performed in all patients.

Introduction

Community-acquired pneumonia (CAP) in adults is a common disorder, potentially life threatening [1], with a high hospitalization rate [2]. It is the only acute respiratory tract infection in which delayed antibiotic therapy has been associated with increased risk of death [3]. Therefore, a correct and rapid diagnosis is mandatory.

Currently, chest radiograph (CXR) is recommended for the routine evaluation of a patient suspected of having pneumonia because medical history and physical examination cannot provide certainty in this diagnosis [4]. However, especially in the emergency department (ED) setting, CXR might have many limitations due to patient conditions, waste of time, and interobserver variability in its interpretation [5].

Computed tomography (CT), on the other hand, is considered to be the gold standard technique, but it is often not available, has high radiation dose, and has high cost [6].

Lungs are traditionally considered poorly accessible to ultrasound (US) investigation because of their air content [7]. Only in the last decade, it has been shown that the US assessment of the lung could have a role in common clinical practice [8].

In lung consolidations, air is replaced by fluid, leading to a good US transmission if there is a direct contact of the lesion with pleural surface [9], [10]. Not many studies were performed in the last years for the evaluation of lung US in the diagnosis of infectious lung diseases [11], [12], [13], [14], [15].

The aim of this study is to assess the ability of bedside lung US to confirm clinical suspicion of pneumonia and the feasibility of its integration in common ED clinical practice.

Section snippets

Setting

The study was conducted in the ED of S. Antonio Abate Hospital, Tolmezzo, Italy, a second-level general hospital, during a 4-month period (from October 4, 2006, to January 15, 2007). This ED usually has about 20 000 visits per year.

Inclusion criteria

Patients not consecutively admitted to our ED with signs and symptoms of CAP were studied. According to the international guidelines [16], [17], [18], [19], the suggestive clinical elements were cough, fever or dyspnea, sputum production, and pleuritic chest pain. In

Results

We studied 49 patients: 18 (36.7%) females and 31 (63.2%) males with a mean age of 60.9 years (SD, 21.8). Positive CXR or CT scan and indirectly the 10 days clinical follow-up confirmed pneumonia in 32 cases (65.3%). In this group, we had 31 (96.9%) positive lung US and 24 (75%) positive CXR (Table 1). Follow-up was always consistent with the diagnosis, showing an improved clinical picture (no fever, cough, or dyspnea) and a drop in inflammatory laboratory indexes such as C-reactive protein.

Discussion

In the present study, the use of CT to clarify contrasting results between lung US and CXR was crucial: if we had considered CXR as the gold standard, we would have had 8 false-positive echographic results (25% of 32 confirmed diagnoses), actually proven to be pneumonia. One of these cases is shown in Fig. 4. This was not caused only by patients' conditions hindering good CXR images: 3 of these patients, as said before, had a double-view CXR. Besides, the 8 negative CXRs were evaluated by a

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Technological advances over the past two decades have paved the way for the prehospital use of ultrasound. This practice was first developed in traumatology and then in a multitude of other indications, including cardiology. The development of pulmonary ultrasound is certainly the most visible illustration of this. Firstly, because it is an extra-cardiac examination that provides the answer to a cardiac question. Secondly because from a theoretical point of view this ultrasound indication was a bad indication for the use of ultrasound due to the air contained in the thorax. Thirdly, because this indication has become a ‘standard of care’ when caring for a patient with dyspnea – a practice that has become widespread during the COVID epidemic. In patients with heart failure, ultrasound has a high diagnostic power (including for alternative diagnoses) which is all the more precise since the technique is non-invasive, the response is obtained quickly, the examination can be repeated at desire to follow the evolution of the patient. The main other indications for prehospital ultrasound are cardiac arrest to search for a curable cause, identification of residual mechanical cardiac activity, monitoring of cerebral perfusion; chest pain, for both positive and negative diagnoses; shock for the search for an etiology and therapeutic follow-up or even pulmonary embolism or ultrasound for the search for dilation of the right ventricle which is now at the forefront of the recommendation algorithm.
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Original ContributionEvaluation of lung ultrasound for the diagnosis of pneumonia in the ED

Abstract

Objectives

Methods

Results

Conclusion

Introduction

Section snippets

Setting

Inclusion criteria

Results

Discussion

Lancet

Chest

Chest

Ultrasound Med Biol

Ultrasound Med Biol

Eur J Ultrasound

Am J Em Med

Chest

Chest

Epidemiology of community-acquired pneumonia in adults: a population-based study

Eur Respir J

Quality of care, process, and outcomes in elderly patients with pneumonia

JAMA

Testing strategies in the initial management of patients with community-acquired pneumonia

Ann Intern Med

High-resolution computed tomography for the diagnosis of community-acquired pneumonia

Clin Infect Dis

Original Contribution
Evaluation of lung ultrasound for the diagnosis of pneumonia in the ED