Ultrasonography in the intensive care unit: a bibliometrics analysis

Introduction

In recent decades, critical care medicine has rapidly developed. In the intensive care unit (ICU), various instruments can be used to monitor and treat patients (1,2). These instruments can obtain real-time and accurate physiological parameters, which has important clinical reference value for understanding changes in the patient’s condition and timely adjusting the treatment plan (3,4). However, some critically ill patients need advanced imaging information during hospitalization in the ICU that may be missed by physical examination. Moreover, image guidance can improve the success rate and shorten the operation time of some procedures, such as blood vessel puncture and catheter implantation (5). Whether by providing accurate diagnostic information in time or by guiding a procedure, ultrasound can contribute to the improvement of the medical treatment and prognosis of critically ill patients. Ultrasound has several advantages over other imaging modalities, including the ability to perform bedside real-time examinations and assess function and pathological changes and of most body organs (6,7). Therefore, in recent years, ultrasonic examination has been widely performed in ICUs, and an increasing amount of relevant research has been published (8). There are several indications of ultrasound in the ICU, including cardiovascular system examination, chest and abdominal fluid evaluation, real-time ultrasound guidance (6,7). Some studies have shown that transthoracic echocardiography can reduce the risk of 28-day death in critically ill patients (9,10). A number of studies have shown that ultrasound examination has important clinical value in the ICU (11-13). In recent years, researchers have also published a large number of reviews, where they summarized and analyzed the application of ultrasonic examination in the ICU. However, there is no systematic review on the overall status of relevant research on the application of ultrasound in the ICU and the status of related studies remains unclear. Bibliometrics searches the literature of a specific subject and then statistically analyzes the relevant information of the literature, such as the country conducting the research, the research institution, and the author of the paper. Through analysis, it can reflect the distribution characteristics of relevant research within a specific time and a specific geographical region. It can also reflect the research focus of this field through keyword analysis. The purpose of this study is to summarize the state of research on ultrasound application in the ICU through bibliometric analysis for investigators.

Methods

Data source

The online Science Citation Index Expanded (SCI-E) database in the Web of Science Core Collection (WOSCC) was used for data retrieval, since it is the most common used database in medical research.

Search strategy

In this study, the literature was searched by applying the following keywords: “ultrasound” OR “ultrasonography” AND “intensive care unit” OR “critical care unit” OR “intensive care” OR “critical care” in a fuzzy method. Literature retrieved by using the above keywords and published were included without specific time limit.

Analysis

All records and references of the search results were exported in plain text format. For literatures related to the utility and research of ultrasonography in critical care practice, numbers of documents, countries, institutions were analyzed, and the relationship (centrality score) between countries, institutions and authors were also analyzed. Related journals, in which those searched literatures were published were also analyzed. Keywords used in these literatures was analyzed.

Statistical analysis

Excel software was used to chart the trend of the number of published documents and the number of cited documents in this field each year. Qualitative data are expressed in terms of quantity and percentage. The information of related literatures was analyzed using the bibliometric software package of R software.

Results

General information

A total of 3,991 relevant research literature records were retrieved in this study, including 276 duplicate records. After removing duplicate records, 3,715 studies were finally included—among them: 244 clinical studies, 80 randomized clinical trials (RCT) studies, 105 systematic reviews, 267 case reports, 159 conference abstracts, and 57 online publications published in advance. Table 1 summarizes the types of publications. The analysis results show that the number of published documents is basically increasing year by year (Figure 1). Moreover, the number of citations in the literature also shows an increasing trend year by year (Figure 1). These documents were cited 86,771 times, with an average of 23.4 times for each document. The analysis of research fields involved in these studies (Table 2) shows that the most common fields are medical imaging, critical care medicine and cardiology.

Figure 1 Annual trends of publications and citations.

Analysis of countries and institutions

The analysis of the source countries of the literature shows that the number of studies published in this field in the United States is significantly higher than that published in other countries (Figure 2). The higher the score, the more research cooperation there is between the country and other countries. The analysis results (Table 3) show that the United States has the highest centrality score; that is, the United States has the highest rate of cooperation with other countries, followed by the United Kingdom, France and other European countries, in terms of performing ultrasounds on critically ill patients. However, China did not rank in the top 10 in terms of the number of published documents and the centrality score. The analysis of the research institutions that published literature about ultrasound in critical care units shows that among the top 10 research institutions (Table 4), 5 are in France, 3 are in the United States, 1 in the United Kingdom and 1 in Canada. The centrality score results reflecting the level of cooperation between research institutions (Table 5) shows that Udice French Research Universities has more cooperation with other research institutions, followed by Assistance Public Hopitaux Paris Aphp and Institut National De La Sante Et De La Recherche Medical. China still has no research institutions in the top 10. We also analyzed the number of papers published by author groups (Table 6), and the results showed that IEEE (American Institute of Electrical and Electronic Engineers) and the Chinese Severe Ultrasound Research Group published the highest number of papers.

Figure 2 Top 10 countries in publications.

Author analysis

The analysis of the author groups (Table 7) shows that many authors in China have been included in the top 10 for the number of published articles, among which Xiaoting Wang and Jihai Liu have published 24 and 23 articles, respectively, ranking first and second among all authors. The other researchers in the top 10 are from Italy, France and the Netherlands. Table 8 summarizes the analysis of the researchers’ centrality scores.

Journal analysis

The journal analysis (Table 9) shows that the journals with the highest number of publications on critical care and ultrasound research are Intensive Care Medicine, followed by Critical Care Medicine and Critical Care. Among the top 10 journals with the largest number of published articles, 5 journals are authoritative journals in the field of critical care medicine. We also showed that among the top 10 journals, there are 4 in the field of obstetrics and gynecology.

Keywords analysis

We analyzed the keywords used in all the included studies, and the results showed that (Table 10) the most frequently used keywords in these studies were “ultrasound”, followed by “critical care”, “ultrasonography”, etc. Among the top 10 keywords, there are six nouns of ultrasound specialty (ultrasound, ultrasonography, point-of-care, transthoracic echocardiography, bedside ultrasound and echocardiography).

Summary of main indication of ultrasonography

We summarized the main indication of the utility of ultrasonography in ICU practice in Table 11.

Discussion

Ultrasound imaging has indeed changed the practice of intensive care medicine. The results of this study show that the application of ultrasound in critical care has shown an obvious growth trend in recent years and has received extensive attention. Many studies have been published in important journals of critical care medicine. The analysis of the distribution of countries and research institutions conducting research shows that the United States has significantly more research in this field than other countries. Moreover, at the national level, the United States have shown to be more cooperative with other countries. The research institutions with the largest number of published documents are Udice French Research Universities and Assistance Publice Hopitaux Paris Aphp from France. The authors analysis shows that in this field, some research has been completed by author groups, including IEEE and the Chinese Critical Ultrasound Study Group. Although some authors from China have published the largest number of papers, they have led relatively few cooperative studies. In terms of journals, the major journals are those of critical care medicine and ultrasound, and a large number of studies are published in authoritative journals. The keyword analysis showed that the keywords related to ultrasound and critical care medicine were used more frequently.

Ultrasonography, especially bedside ultrasound, has important clinical value for examining critically-ill patients. In the ICU, ultrasound is mainly used in the following situations: to evaluate the structural and functional changes of the heart; understand the hemodynamic state of the patient; evaluate pneumonia and pulmonary edema; evaluate the morphological changes and functions of abdominal organs; evaluate whether there is bleeding and effusion in the abdominal cavity; and assess the wound tissue. Bedside ultrasound can be used to monitor the inferior vena cava collapse index (IVC-CI) in order to evaluate the right heart pressure and circulation volume status (14). Many studies have shown that the IVC-CI has a good correlation with the central venous pressure (CVP) and pulmonary thromboembolism (15,16). Bedside ultrasound plays a key role in rescue after resuscitation by dynamically monitoring changes in the cardiac structure (17). Another study showed that ultrasound has high sensitivity and specificity in the diagnosis of acute pulmonary embolism (18). Transthoracic echocardiography can quickly and accurately observe changes in the cardiac structure and function and judge whether the heart stops, whether there is cardiac rupture, pericardial effusion (blood), etc. It can definitively have an influence on the treatment approach (9,19,20). Adult respiratory distress syndrome often leads to acute cor pulmonale (21). Previous studies found that 3 days before patients with acute respiratory distress syndrome (ARDS) are placed under mechanical ventilation, cardiac ultrasound examination can assist in accurately adjusting the mechanical ventilation parameters and reducing the incidence of acute cor pulmonale and overall mortality (22,23). Off-line cardiac ultrasound examination is beneficial for risk assessment in these patients (24). Other research results show that the accuracy of lung ultrasound in diagnosing severe pneumonia is higher than that of procalcitonin and C reactive protein—therefore, ultrasound can be used as a reference index for diagnosing pneumonia that can be controlled and prevented early. Relevant studies have shown that the lung ultrasound score has a high diagnostic efficiency in detecting novel coronavirus pneumonia in patients with ARDS and can be used as an important reference index for diagnosis (25-27). Besides, endobronchial ultrasonography has been successfully used in the ICU and helped clinicians to better understand and treat bronchial problems (28).

Ultrasound also has important clinical value in monitoring and evaluating the condition of patients with severe trauma. The condition of some trauma patients may be aggravated by frequent movement due to their severe injuries. Bedside ultrasound can be used to evaluate these patients in real time. Focused assessment with sonography in trauma (FAST) and extended focused assessment with sonography in trauma (E-FAST) are bedside ultrasound examination methods that are suitable for rapid assessment of internal bleeding in trauma patients (29-31). Some studies have shown that for patients with severe trauma, ultrasonic examination is helpful in determining the patient transfer facility, thus affecting the survival rate of trauma patients (32,33). Bedside ultrasound can more intuitively show the two-dimensional (2D) shape and structure of thoracic and abdominal organs and large vessels, and abnormal changes in the hemodynamic situation can be clearly understood using color Doppler imaging (34).

In addition to the examination and evaluation of important organs, ultrasound can also assist blood vessel puncture, tissue puncture, and various catheterizations (35-38). In critically-ill patients, there may be venous collapse, tissue edema, and tissue trauma, which can lead to difficulties in puncture or catheter placement. Ultrasound can show the anatomical morphology of the target blood vessels and pipes and the position of the head of the puncture needle or catheter in real time, guiding the operator to adjust in real time to improve the success rate of puncture or catheterization (39,40).

Through the statistical analysis of the literature related to the application of ultrasound in the practice of critical care medicine, this study shows the state of current research in this field, including the distribution of countries conducting research, the distribution of research institutions, the distribution of authors, the cooperation in research, the characteristics of journals publishing relevant articles, and the use of keywords in related literature. There are some limitations in this study. First, this study uses the keyword retrieval strategy. In a few studies, although researchers assessed the role of ultrasound in the practice of critical care medicine, they did not focus on ultrasound, and some relevant literature may be missing from the keyword retrieval. Second, this study is based on English literature only, and therefore some relevant articles may have been missed.

Conclusions

Based on this bibliometrics analysis of the literatures on ultrasonography in the ICU, we found that relevant research is mainly concentrated in Europe and in the United States, and research in this field has become the center of attention. Chinese research institutions should perform more studies in this field and increase cooperation with other institutions from other countries.

Acknowledgments

Funding: None.

Footnote

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-23-1190/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-23-1190/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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