Comparison of Permissive Hypotension vs. Conventional Resuscitation Strategies in Adult Trauma Patients with Hemorrhagic Shock: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Authors: Zhang Yang , Ding Yaping , Zheng Dongbin , Huang Xusheng , Zhang Junhui , Liang Wei , Huang Zhuangrong , Zhu Shu-Guang 
Published: April 2021

Abstract
BackgroundThere is still an ongoing battle against the Permissive Hypotension (PH) through Conventional Resuscitation Strategies (CR). Active fluid resuscitation in patients with traumatic shock can bring many problems, as it is known that standard high-volume resuscitation can exacerbate the lethal triad of acidemia, hypothermia, and coagulopathy. As a part of damage control resuscitation strategy, it can reduce mortality and shorten hospital stay, compared with the use of standard liquids. Moreover, its application is gradually receiving wider attention (1) . This review evaluated the effectiveness and safety of permissive hypotension resuscitation in adult patients with traumatic hemorrhagic shock.MethodsThe systematic review and meta-analysis were conducted according to PRISMA guidelines. We searched PubMed, EMBASE and Cochrane databases for randomized controlled trials (RCTs) from the beginning to March 2021 to compare the therapeutic effects of controlled fluid resuscitation and conventional fluid resuscitation on patients with traumatic hemorrhagic shock. Two reviewers independently conducted screening, data extraction and bias assessment. Data analysis was performed using Cochrane Collaboration Software Revman 5.2. The primary outcome was 30-day or in-hospital mortality. Secondary outcomes included blood routine index, coagulation function, resuscitation fluid use, complications, and length of hospital stay. Pooling was performed with a random-effects model.Results8 randomized controlled trials were screened out of 898 studies and 1593 patients were evaluated. The target blood pressure of the intervention group ranged from 50-90 mmHg in systolic pressure or mean arterial pressure ≥ 50 mmHg, while that of the control group was 65-110 mmHg systolic pressure or mean arterial pressure ≥ 60 mmHg. Only patients with penetrating injuries were evaluated in two studies, while the remaining six included blunt injuries. A statistically significant reduction in mortality was observed in the intervention group (RR = 0.70; 95%CI= 0.58-0.84; P < 0.05). Small heterogeneity was observed in the included articles (χ2 = 8.9; P = 0.18; I2 = 33%). The loss of platelet (PLT), hemoglobin (Hb) and body fluid was properly protected, the amount of resuscitation fluid was reduced, and the incidence of some adverse events was effectively reduced. There was no significant difference in coagulation time and hospital stay between the two groups.ConclusionsThis meta-analysis reveals the survival benefits of hypotension resuscitation in patients with traumatic hemorrhagic shock. The significant advantage is to promote the recovery of patients' physical function and reduce the incidence of treatment-related complications such as acute respiratory distress syndrome (ARDS), acute kidney injury (AKI) and multiple organ dysfunction syndrome (MODS), which reduces the mortality. Convincing evidences are provided based on these results, but larger, multicenter, randomized trials are needed to confirm the findings.