1 Introduction
With the increase of vehicles and large machinery, trauma has become the most common cause of death for the people under 44 years old,[1] [2] [3] Traumatic hemorrhagic shock refers to a series of reaction syndromes caused by injury to and bleeding of the viscera, decreased effective circulating blood volume and insufficient microcirculation perfusion.[4,5]
The most effective treatment for hemorrhagic shock is usually surgery, but how resuscitation should be chosen prior to surgery has not been determined.[6,7] traumatic hemorrhagic shock: aggressive resuscitation and hypotensive resuscitation.[8] [9,10] [11] traumatic hemorrhagic shock.
In the preliminary data preparation process, we found that there was a similar previous meta-analysis study,[12]
2 Methods
2.1 Design and registration
A meta-analysis will be conducted to systematically evaluate the efficacy of hypotensive resuscitation in patients with traumatic hemorrhagic shock. This protocol has been registered on the international prospective register of systematic reviews (PROSPERO), registration number: CRD42019133169 (https://www.crd.york.ac.uk/PROSPERO
2.2 Study selection
2.2.1 Study type
This study will include Randomized Controlled Trials (RCTs).
2.2.2 Study object
The study objects had the following requirements:
1. adult patients;
2. a clear diagnosis of shock; and
3. trauma and blood loss.
2.2.3 Intervening measure
Patients will be randomized into 2 groups: the hypotensive resuscitation (HR) group and the conventional resuscitation (CR) group. In the hypotensive resuscitation group, patients will receive less fluid resuscitation, keeping their blood pressure at a lower level, while in the conventional resuscitation group, patients will receive conventional fluid resuscitation, keeping their blood pressure at a normal level.
2.2.4 Outcome indicator
The following outcomes will be compared between the HR group and CR group:
1. overall mortality,
2. 24-hour mortality.
2.2.5 Exclusion criteria
Studies that investigated other causes of shock including neurogenic shock, surgical bleeding shock, and hysterorrhexis shock will be excluded. Studies with data that could not be extracted or utilized, animal experiments, and literature reviews, and other types of non-experimental articles will be excluded.
2.3 Data sources and searches
We searched English language publications through September 2019 using the following databases: Web of Science, PubMed, the Cochrane Library, EMBASE, and Clinical Trials. The search terms were “hypotensive resuscitation”, “hemorrhagic shock”, and “trauma”. Here, we use the PubMed database as an example (Fig. 1 ).
Figure 1: Retrieval strategy for the PubMed database.
2.4 Study screening, data extraction, and risk assessment of bias
Data will be collected independently by 2 researchers. The unqualified studies will be eliminated, and the qualified ones will be screened by reading the title, abstract, and full text. Then, the research data will be extracted and checked, and disagreements will be discussed or a decision was made by the author. The extracted data will include the following:
1. basic information of the study, including title, author, and year of publication;
2. characteristics of the included study, consisting of study duration, sample sizes of the intervention group and the control group, and intervention measures;
3. outcome indicators and the data included; and
4. the elements needed to perform a risk assessment for bias.
The risk of bias in the included studies will be assessed using the RCT bias risk assessment tool recommended in the Cochrane Handbook for Systematic Reviews of Interventions (5.1.0).
2.5 Statistical analysis
Revman 5.3 software will be used for the meta-analysis. The relative risk (RR) will be used as an effect indicator for dichotomous variables, and the estimated value and 95% confidence interval (CI) will be included as effect analysis statistics. A heterogeneity test will be conducted with the results of each study. To make the results more stable, the random effects model, a more conservative effects model, will be adopted in this meta-analysis. The significance level will be set at α = 0.05.
2.6 Subgroup analysis
Subgroups will be established based on quality evaluation of studies.
2.7 Assessment of publication bias
If more than 10 articles are available for quantitative analysis, we will generate funnel plots to assess publication bias. A symmetrical distribution of funnel plot data indicates that there is no publication bias, otherwise, we will analyze the possible cause and give reasonable interpretation for asymmetric funnel plots.
2.8 Confidence in cumulative evidence
GRADE[13]
3 Discussion
Hypotensive resuscitation is an established method.[14] traumatic hemorrhagic shock, there are few RCTs to support this recommendation.[15,16]
First, we found that the CNKI database was retrieved in the previous meta-analysis. I take a negative attitude towards this. Including the CNKI database could increase the number of studies included, but after carefully reading the full texts of these available studies, it was determined that the quality of research in the CNKI database is uneven. After weighing quantity and quality, this meta-analysis will not include the CNKI database. Then compared with the previous meta-analysis, the RCT bias risk assessment tool recommended in the Cochrane Handbook for Systematic Reviews of Interventions will be used. By analyzing the random sequence generation, allocation concealment, blinding method, incomplete outcome data, selective reporting, etc, to evaluate the quality of the research.
Researchers think that during the early stages of trauma, aggressive resuscitation could reduce the patient's core temperature, and excessive infusion could dilute the clotting factor. Meanwhile, raising blood pressure could result in the loss of red blood cells, leading to hypoxia in tissues and acidosis. These 3 conditions (hypothermia, clotting disorders, acidosis) are referred to as the triangle of death.[17] [18]
Why are the results of RCTs not as good as the theory? In actual clinical practice, it is difficult to control blood pressure in a short time to the target pressure. In hypotension resuscitation, the fluctuation of blood pressure will inevitably cause tissue ischemia and hypoxia, and cause tissue damage. This might be HR's weakness.
This study will conduct a meta-analysis of related RCTs, and provide evidence on the efficacy and safety of hypotensive resuscitation in traumatic hemorrhagic shock treatment, so as to better guide clinical practice.
Hua Wang orcid: 0000-0002-7288-5907.
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