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Global Translational Medicine Hydrogen for acute lung injury

3. Results which needed to be calculated using Equation I [22,37] , while
other studies used standard differences [20,21,23-36,38] .
3.1. Study retrieval and selection
In the present paper, we identified 390 potentially relevant 3.3. Assessment of the risk of publication bias
studies using the search protocol described above. All included studies were checked and scored through the
After applying the inclusion and exclusion criteria, 50 CAMARADES checklist to evaluate their methodological
studies were selected based on their titles and abstracts. quality. The scores ranged from three to seven, with
Subsequently, 30 articles lacking the necessary data were an average score of 4.75. A detailed summary of
excluded, resulting in a final set of 20 studies used for this methodological quality results is provided in Table 2.
meta-analysis. The selection diagram is shown in Figure 1. Moreover, all included studies passed the peer-review
process [20-38] . Out of 20 studies, 10 studies implemented
3.2. Characteristics of the included study temperature control during the experimental sta
The main characteristics of these 20 studies are presented ges [21-24,26,28-30,33,37,38] . However, two studies did not provide
in Table 1. These studies were published between 2010 and random allocation [20,27] . In addition, only seven studies
2021, encompassing a total of 406 subjects, with 203 in conformed to the use of anesthetic without significant
the experimental group and 203 in the control group. The intrinsic neuroprotective activity [22,24,26-29,34] . Three studies
species studied in the included studies can be classified into were found to have non-compliance with animal welfare
five categories: (i) C57BL/6 mice [20-22] ; (ii) ICR mice [23,24] ; (iii) regulations [24,26,35] . Regarding the disclosure of potential
[25]
Kunming (KM) mice ; (iv) SD rats [26-37] ; and (v) Wistar conflicts of interest, only four studies provided and
rats [38,39] . These studies covered 7 types of ALI animal declared such statements in their research [28,33,35,38] .
models: (i) Smoke inhalation ; (ii) cecal ligation and 3.4. Outcome indicators of the included studies
[39]
puncture [20-22,27,32] ; (iii) lipopolysaccharide (LPS) [25,30-32,39] ;
(iv) oleic acid (OA) [33,34] ; (v) burnt injury ; (vi) ischemia/ 3.4.1. W/D ratio
[26]
reperfusion (I/R) [28,29,37] ; (vii) paraquat (PQ) [24,26,35] . The W/D ratio was used as an outcome index in 12
Regarding interventions, hydrogen saline was used in 12 studies. All these studies provided complete data and
studies [26-35] , and 2% H was used in eight studies [20-23,25,36-38] . showed positive effects of 2% H and hydrogen saline
2
2
Two studies used standard error to represent the effect size, in reducing the W/D ratio. The findings revealed

Figure 1. Study flow chart of studies retrieval and selection. The inclusion and screening were conducted by two reviewers. The first stage was filtered by
the title and abstract. In the second stage, screening was conducted again based on the full text of the remaining studies after screening. Finally, studies of
hydrogen therapy-treated ALI animal models were selected.

Volume 2 Issue 3 (2023) 4 https://doi.org/10.36922/gtm.0379