Original Contribution
A simplified ultrasound-based edema score to assess lung injury and clinical severity in septic patients

https://doi.org/10.1016/j.ajem.2013.08.053Get rights and content

Abstract

Background

Lung ultrasound (US) is an excellent tool to assess lung edema in a myriad of different clinical situations. We hypothesized that lung US might also be a good prognostic and management instrument in septic patients, regardless of disease severity.

Methods

This was a prospective observational cohort study at an urban academic emergency department (ED). Inclusion criteria were as follows: septic patients, at least 18 years old, admitted at the ED of a tertiary hospital. A simplified lung edema scoring system (SLESS) was developed, and 6 thoracic regions were evaluated. Four different lung US patterns were considered, from normal aeration to total consolidation. To evaluate disease severity, the SLESS was compared with the Mortality in Emergency Department Sepsis Score and the third version of the Simplified Acute Physiology Score scoring systems. Aiming to assess the effect of the lung edema in the gas exchange, the SLESS was compared with the Pao2/fraction of inspired oxygen ratio.

Results

Sixty-one patients were enrolled in a 3-month period. The SLESS had a good correlation with the Mortality in Emergency Department Sepsis Score and Simplified Acute Physiology Score (r = 0.53 and r = 0.55, respectively; P < .001 for both) and a negative correlation with the Pao2/fraction of inspired oxygen ratio (r = − 0.62; P < .001). The SLESS also showed correlation with the respiratory rate (r = 0.45; P = .0003). The odds ratio for death related to the SLESS was 1.370 (95% confidence interval, 1.109-1.691; P = .0035).

Conclusion

The SLESS is an easy and practical scoring system. It might be a useful tool to predict severity of disease in sepsis patients. The SLESS might also be able to be correlated with the oxygen exchange.

Introduction

Sepsis is an emerging public health issue worldwide [1], [2], [3], [4]. Severe sepsis and septic shock have high rates of mortality and represent an important burden in terms of social and economic costs [5], [6]. Brazilian epidemiology studies have shown even more concerning data [7], with higher mortality rates. The last report of the Latin American Sepsis Institute, published earlier in 2013, showed that Brazilian mortality for severe sepsis and septic shock (34.8% and 64.5%, respectively) are higher than that of the developed countries [8].

The recognition of sepsis represents a challenge to the physician due to the lack of specific signs and symptoms, which might lead to a poor compliance with the best evidence-based treatment [9], [10]. The development of sepsis-induced organ damage increases significantly the risk of death [11]. For this reason, the Surviving Sepsis Campaign developed evidence-based guidelines to improve sepsis management. Within such guidelines, the cornerstone is early recognition of suspected infection to implement the appropriate therapy in a time-sensitive manner [12].

Many different clinical and laboratory parameters can be altered in the initial course of the septic insult, and occult severity might be present despite of patient's stable appearance [13], [14]. Therefore, the development of reliable methods of identifying patients at most risk of dying would be important. In the intensive care unit, several scoring systems were developed to measure disease severity and predict the risk of death. Of note, the third version of the Simplified Acute Physiology Score (SAPS3) included, in its cohort, a subset of Brazilian patients, and practically all of its variables are affected by sepsis [15], [16]. In the emergency department (ED), the Mortality in Emergency Department Sepsis Score (MEDS) was developed to evaluate disease severity based on initial clinical and laboratory criteria [17].

Respiratory failure is one of the most common complications of sepsis [18], and it is the clinical consequence of the development of the acute respiratory distress syndrome (ARDS) [19], which is a nonhydrostatic pulmonary edema, caused by a wide range of acute diseases. Patients that develop ARDS have a mortality that ranges from 27% to 45% [20]. The early recognition of lung edema is important to establish the correct treatment. However, thoracic examination might be poor and chest radiograph might be nonspecific in the initial course of the disease [18], [21].

Lung ultrasound (US) has been increasingly used in the ED for the diagnosis of a variety of pathologies [22]. Of note, 1 study by Volpicelli et al [23] analyzed the efficacy of a point-of-care US protocol for the diagnosis of undifferentiated nontraumatic hypotension in the ED. In their cohort, a subset of septic patients was included. However, the use of lung US in the initial assessment of sepsis severity has not yet been studied. Therefore, we developed a simplified US-based lung edema scoring system (SLESS) for that purpose.

The aim of this study was to evaluate whether the SLESS correlates with sepsis severity measured by 2 scoring systems and with gas exchange measured by the Pao2/fraction of inspired oxygen (Fio2) ratio.

Section snippets

Study design

This was a prospective opportunity sample study of adult septic patients designed to develop a practical lung edema scoring system using US and to test its efficiency on predicting the severity of disease as well as its correlation with gas exchange measured by the Pao2/Fio2 ratio. The institutional ethics committee of the attending hospital approved the study. Written informed consent was given to the patients and/or to their families.

Study setting

This study was performed in the ED of a public urban

Results

Over the 3-month period, 61 patients were enrolled. The mean age was 47.1 years, and male patient outnumbered female ones. The total time of lung examination was not quantified, but complete examinations rarely lasted for more than 5 minutes, including the time to start the machine, to insert patient's identification, to load the transducer, to perform the scans, and to save the examination. After the examination was made, an extra time of up to 5 minutes was spent to analyze the data obtained.

Discussion

Several studies have demonstrated the role of the point-of-care lung US on enhancing the diagnostic capability of the attending physician in many different situations, such as the differential diagnosis of acute respiratory failure [24], cardiac pulmonary edema [27], chronic obstructive pulmonary disease exacerbations [28], pneumothorax [29], atelectasis [30], among others [31], [32], [33].

Other elegant studies, some of them made in more controlled environments, have developed different scoring

Conclusions

The proposed score is simple and easy to use. It is related both to sepsis severity and to the gas exchange defect and might be a useful complementary tool to assess disease severity in septic patients.

Acknowledgments

This work was funded by grants from Fundação de Amparo à Pesquisa do Estado de São Paulo. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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    This work was funded by grants from Fundação de Amparo à Pesquisa do Estado de São Paulo. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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