Global trend of review articles focused on cardiopulmonary bypass: Perspectives from bibliometrics

Abstract

BACKGROUND

Cardiopulmonary bypass (CPB) is a life-support technology widely used in surgery. Review articles reflect research advances in a certain topic or field within a certain period of time.

AIM

To perform a bibliometric analysis of the review articles that focused on CPB for cardiovascular surgery.

METHODS

This study was based on a bibliometric analysis. Data were acquired from the Web of Science and basic bibliometric parameters were analyzed and visualized using VOSviewer and Excel.

RESULTS

We identified 141 review articles on CPB. Generally, the number of publications increased, and most of them were published in the 2010s (n = 57, 40.4%) and the 2020s (n = 45, 31.9%). There were 113 (80.1%) narrative review articles, 21 (14.9%) meta-analysis studies and 7 (5.0%) systematic review papers. The United States (n = 25, 17.7%) and China (n = 21, 14.9%) were the leading countries in terms of publication number. The articles were published in 98 different journals. The Journal of Cardiothoracic and Vascular Anesthesia (n = 14, 10.0%) and Perfusion-United Kingdom (n = 11, 7.8%) were preferred by the authors. The high-frequency keywords included inflammatory response, children, acute kidney injury, meta-analysis and off-pump, except for CPB and cardiac surgery. Inflammatory response had the closest relationship with CPB during cardiac surgery. The complications of CPB, including inflammatory response, kidney injury and ischemia, caught lots of concern.

CONCLUSION

The rapid increase of review papers shows that the research on CPB in cardiac surgery is increasingly being emphasized by scholars and clinical staff worldwide. Meta-analysis has been widely conducted to analyze clinical controversies and further guide clinical practice. Strategies to improving the outcomes of patients undergoing cardiac surgery with CPB are the hot spots in this field.

Key Words: Cardiopulmonary bypass; Review article; Bibliometric analysis; Cardiac surgery; Hot spots

Core Tip: The present study analyzed the characteristics of review articles on cardiopulmonary bypass. The primary findings include: (1) The 141 review articles in Web of Science were identified, of which 113 (80.1%), 21 (14.9%) and 7 (5.0%) were narrative review, meta-analysis and systematic review, respectively; (2) The United States and China published most articles; and (3) Keywords analysis showed that inflammatory response, kidney injury and ischemia were highly focused in this field.

INTRODUCTION

Cardiopulmonary bypass (CPB), also called extracorporeal circulation, is a life support technology that uses a series of special artificial devices to drain the returning venous blood outside the body, exchange gas, regulate temperature, filter it manually, and then transfuse it back into the arterial system of the body[1]. In the process of extracorporeal circulation, the artificial device replaces the human body function; therefore, an extracorporeal circulation machine is also called an artificial heart-lung machine. The purpose of CPB is to maintain the blood supply to tissues and organs throughout the body during open-heart surgery[1]. Merendino was the first surgeon who successfully conducted a series of cardiac surgery by CPB in the United States[1,2]. With the development of clinical medicine, the use of extracorporeal circulation continues to expand. It is not only applied in heart, liver, kidney, lung and other large vascular surgery, but has also made remarkable achievements in tumor treatment and life support for patients with cardiopulmonary failure, and has become an important technology in clinical medicine[3-7].

Although there have been many advances in CPB and cardiac anesthesia, such as hemodilution, mechanical components, heparin management, potential of hydrogen (pH) management, application of transesophageal echocardiography, and protection of major organs, high-level evidence of how we conduct CPB remains lacking[8]. More randomized controlled trials and large-sample cohort studies are still needed. Therefore, it is crucial to have a thorough knowledge of CPB research progress.

Review articles reflect research advances in a certain topic and field within a certain period of time. The primary aim of this study was to perform a bibliometric analysis of review articles that focused on CPB for cardiovascular surgery.

MATERIALS AND METHODS

Data acquirement and analysis

The Web of Science (WoS) database was used as the data source. To include as many related articles as possible, all databases in WoS, such as MEDLINE, WoS Core Collection (WoSCC), SciELO Citation Index and Chinese Science Citation Database, were used for literature retrieval. Reviews focusing on both CPB and cardiovascular surgery were eligible for inclusion. The following formula was applied: [TI = (CPB) OR TI = (extracorporeal circulation) OR TI = (heart-lung machine) OR TI = (cardiopulmonary support)] AND [TI = (cardiac surgery) OR TI = (heart surgery) OR TI = (cardiovascular surgery)]. The option “Review Article” of the filter “Document Type” was selected. No other restrictions were imposed. The literature retrieval was conducted on 6 March 2024.

Two investigators independently screened the records and removed articles with unmatched document types or research topics. Eligible records were consequently extracted into an excel file. Information such as journal impact factor (IF) and Journal Citation Report (JCR) location were manually extracted from WoS, except journals that were not enrolled in JCR or did not have an IF. For journals belonging to more than one category, the highest JCR location was displayed in our study. Through an artificial review of the articles, we determined the study population (adults, pediatric patients and uncertain patients) and document type (systematic review, meta-analysis and narrative review). Other parameters, such as publication number, were analyzed using WoS or Excel. Descriptive statistical methods were employed to analyze the distribution of publication year, publication number, and number of citations. Owing to the peculiarity of the VOSviewr software and the items in different databases, records from WoSCC were used to analyze keywords using VOSviewer. The synonyms for the keywords were merged.

RESULTS

In total, 148 records focused on CPB during cardiovascular surgery. Among them, 3 records discussed non-cardiac surgery and 4 were not review articles. Thus, 141 review articles were included in the analysis.

Distribution of study population, study type, language and database

The study population and type were determined based on the titles and abstracts of the articles. Nineteen articles focused on adult patients, 28 on pediatric patients, and 94 did not stress adults or children (Figure 1A). There were 7 pure systematic reviews, 21 meta-analysis papers and 113 narrative reviews (Figure 1B). As shown in Figure 1C, the number of articles written in English, Chinese, German, French, Russian, Polish, Hungarian, Italian, Portuguese, Hebrew and Spanish were 105, 10, 7, 4, 4, 3, 2, 2, 2, 1 and 1, respectively. Most of the articles were collected by WoSCC (n = 97), followed by MEDLINE (n = 33), the Chinese Science Citation Database (n = 10) and the SciELO Citation Index (n = 1) (Figure 1D).

Figure 1 Distribution of study population, study type, language and database. A: Distribution of study population; B: Study type; C: Language; D: Database. WoSCC: Web of Science Core Collection.

Analyses of publications and citations by time

The first review in this area was published in 1969 and the latest was published in 2024. Considering the long timeline, we divided the time periods according to our definition. Most of the articles were published after the 2010s; that is, 57 were published in the 2010s and 45 were published in the 2020s (Figure 2). In addition, the number of publications from 1969 to 1999 was comparable to that of the 2000s (18 and 21, respectively) (Figure 2). The total number of citations of the articles in each period is shown in Figure 2. Articles in the 2010s had the most citations, followed by those in the 2000s, 1969–1999, and the 2020s. However, the trends in the mean number of citations were different. The descending order was the 2000s, the 2010s, 1969-1999, and the 2020s.

Figure 2  Number of publication and citation in the time intervals.

Contributions of the authors and countries/regions

The first review of this field was published by German in 1969. The information of the top-10 authors in terms of publication number is presented in Table 1. There were 4 authors with 4 publications, and 7 authors with 3 publications. The authors came from 5 hospitals of 5 countries (Greece, Turkey, Italy, Singapore and England). Six of them specialized in cardiothoracic surgery, 4 majored in pediatric critical care medicine, and 1 was an anesthesiologist.

Table 1 Information of the top-10 authors on publication number.

Authors	Documents	Cited times	H-index	Affiliations	Countries	Departments
Anastasiadis K	4	208	3	Ahepa University Hospital	Greece	Department of Cardiothorac
Antonitsis P	4	208	3	Ahepa University Hospital	Greece	Department of Cardiothorac
Argiriadou H	4	208	3	Ahepa University Hospital	Greece	Department of Cardiothorac
Deliopoulos A	4	208	3	Ahepa University Hospital	Greece	Department of Cardiothorac
Gunaydin S	3	126	3	Ankara City Hospital	Turkey	Department of Cardiovasc Surg
Ranucci M	3	182	3	IRCCS Policlin San Donato	Italy	Department of Cardiovasc Anesthesia and Intens Care Unit
Hwang NC	3	28	3	Singapore Gen Hospital	Singapore	Department of Anaesthesiol
Murdoch IA	3	31	3	PICU Evelina London Childrens Hospital	England	Department of Women and Childrens Health
Hunt BJ	3	31	3	PICU Evelina London Childrens Hospital	England	Department of Women and Childrens Health
Siemens K	3	31	3	PICU Evelina London Childrens Hospital	England	Department of Women and Childrens Health
Tibby SM	3	31	3	PICU Evelina London Childrens Hospital	England	Department of Women and Childrens Health

Table 2 shows the top-10 countries in terms of publication number. With 25 review papers, the United States was the number one in this field, closely followed by China (n = 21). Regarding the cited times of the articles, countries in North America and Europe took the leading position, including the United States, Canada, Germany, Italy, the Netherlands, Greece and England. We further analyzed the number of publications in different time of the top-10 countries. Five countries, namely, China, the Netherlands, Italy, Greece and England, started to publish review articles focused on CPB in the 2010s (Table 3). Besides, Germany, France, Canada and the United States started to summary the advances in CPB in the early stages (Table 3).

Table 2 The top-10 countries in term of publication number.

Countries	Documents	Cited times	H-index
United States	25	623	11
China	21	123	6
Germany	13	335	7
Canada	10	219	5
Netherlands	9	280	5
England	7	224	5
France	7	154	4
Italy	7	296	5
Brazil	6	23	3
Greece	6	238	4

Table 3 Number of publications in different time of the top-10 countries.

Countries	T1	T2	T3	T4	Time span
United States	4	1	10	10	1994-2023
China	0	0	8	13	2014-2024
Germany	2	3	4	4	1969-2023
Canada	1	0	6	3	1994-2023
Netherlands	0	0	4	5	2011-2023
England	0	0	3	4	2016-2023
France	1	1	4	1	1980-2023
Italy	0	0	4	3	2010-2023
Brazil	0	1	4	1	2004-2023
Greece	0	0	4	2	2012-2023

T1: 1969-1999; T2: 2000-2009; T3: 2010-2019; T4: 2020-2024.

Journal analysis

A total of 98 journals recorded the 141 review articles. Der Anaesthesist, a German journal, published the first review on CPB. The Journal of Cardiothoracic and Vascular Anesthesia published 14 papers, closely followed by Perfusion-United Kingdom (n = 11). The 2 journals were far ahead of the other journals (Table 4). Considering the decentralized distribution of the articles, we only exhibited the top-5 journals in terms of publication number and the publication timeline in Table 4.

Table 4 Top-5 journals on publication number and the number of publications in different time.

Source title	Documents	If of 2022	IF of 5-year	Journal Citation Report quartile	Time span	T1	T2	T3	T4
Journal of Cardiothoracic and Vascular Anesthesia	14	2.8	2.5	Q3	1999-2022	1	0	10	3
Perfusion- United Kingdom	11	1.2	1.4	Q4	1997-2023	1	1	2	7
Cochrane Database of Systematic Reviews	4	8.4	10.9	Q1	2018-2022	0	0	2	2
The Journal of Extra-Corporeal Technology	4	-	-	-	2003-2010	0	3	1	0
Journal of Cardiac Surgery	3	1.6	1.6	Q3	1994-2022	1	0	0	2

IF: Impact factor. T1: 1969-1999; T2: 2000-2009; T3: 2010-2019; T4: 2020-2024.

Keywords analysis

Co-occurrence analysis of the keywords (provided by the authors and WoS) is shown in Figure 3. The high-frequency keywords included inflammatory response, children, acute kidney injury, meta-analysis and off-pump, except for CPB and cardiac surgery. Inflammatory response had the closest relationship with CPB during cardiac surgery. This map provides several additional clues. For instance, some technological factors of CPB, such as heparin and hemodilution, have received considerable attention. The complications of CPB, including inflammatory response, kidney injury and ischemia, caught lots of concern.

Figure 3  Co-occurrence analysis of the keywords.

DISCUSSION

As the first bibliometric analysis of review articles on CPB, the present study recognizes the development and the worldwide contributions within this surgical topic. Most of the reviews were published in this century (123 publications, 87%), and the publication speed has increased significantly.

The first review paper, entitled Postoperative monitoring following surgery with use of the heart-lung machine, was published in 1969 in Germany[9]. Within 20 years of the successful application of CPB, medical staff have summarized the postoperative monitoring for cardiac patients, which is of great importance to increase the survival rate. Pharmacological and non-pharmacological strategies to optimize CPB have been proposed and verified, including hemodilution, mechanical components, heparin management and pH management[10-13].

With 213 citations, this article Postoperative pulmonary dysfunction in adults after cardiac surgery with cardiopulmonary bypass: Clinical significance and implications for practice was the most influential review in this field[14]. Published in 2004, this review focuses on the significance and implications of postoperative pulmonary dysfunction in nursing practice. Influenced by this review, improvements of nursing have been investigated to help with fast recovery[15,16].

One interesting thing is that the latest several publications are mainly meta-analysis articles. One of them systematically evaluated the role of electroacupuncture in improving myocardial function and postoperative rehabilitation for CPB-based cardiac patients[17]. The authors declare that electroacupuncture is a promising treatment for alleviating myocardial ischemia-reperfusion injury and enhancing patient recovery. However, considering the low or moderate quality of most evidence, these findings need to be further verified by more high-quality randomized controlled trials. Another protective strategy involves the use of dexmedetomidine. There are 3 meta-analysis articles to determine the role of dexmedetomidine in cardiac surgery with CPB. The first study was published in 2021 by Zhang et al[18]. This study focused on the influence of dexmedetomidine on myocardial ischemia/reperfusion injury, and the results indicated that markers of myocardial injury and length of intensive care unit stay were significantly reduced by dexmedetomidine. The second study was published in 2022 by Chen et al[19]. In this study, the myocardial protective and anti-inflammatory effects of dexmedetomidine were investigated by analyzing 9 randomized controlled trials involving 418 participants. These results indicate that dexmedetomidine administration during CPB reduces myocardial injury by inhibiting inflammatory responses. Additionally, the last but the latest one was a study protocol for a meta-analysis which intended to provide support for the role of dexmedetomidine in reducing myocardial ischemia/reperfusion injury in patients undergoing CPB-based cardiac surgery[20].

The primary theme identified in keywords analysis is the inflammatory response, a physiopathologic process that related to self-protection and injury[21]. An overactivated inflammatory response can lead to severe impacts on major organs, such as acute kidney injury and lung injury[22,23]. Major organ dysfunction is strongly associated with adverse prognosis in surgical patients. The high- frequency of outcome-related keywords in this study is in accordance with the truth.

Limitations of the present study must be pointed out. Firstly, we only reviewed papers in the WoS database, which undoubtedly misses some studies and limits our findings. A common concern for bibliometric analysis is that because citations are affected by time, newly published articles are likely to be more influential. We also did not take the self-citations into consideration, or whether the articles are positively or negatively cited. Hence, we cannot determine the evaluation from the academic community to the cited articles.

CONCLUSION

CPB is a vital technique used in cardiac surgery. The rapid increase of review papers shows that the research on CPB in cardiac surgery is being increasingly emphasized by scholars and clinical staff worldwide. The leading countries mainly distribute in North America, Europe, except for China. Meta-analysis has been widely conducted to analyze clinical controversies and further guide clinical practice. Strategies to improve the outcomes of patients undergoing cardiac surgery with CPB are the hot spots in the field.