Superficial Vs. Deep System Single Venous Anastomosis In The Radial Forearm Free Flap:A Meta-Analysis

Objective The radial forearm free flap(RFFF)has frequently been used for head and neck reconstruction.It is safe and easy to obtain this flap for reconstruction because of the ease of dissection,the large caliber of the blood vessels,and the pliable nature of the thin subcutaneous fat.Selection of the appropriate venous anastomosis is beneficial in reducing the frequency of flap loss.There are two drainage systems in the RFFF;the superficial system and the deep system.Selection of the most suitable drainage system for an RFFF remains a controversial decision.We use systematic review and meta-analysis to collect relatively literature about postoperative outcomes of superficial system and deep system in the RFFF,then analysis venous compromise(Venous thrombosis and inadequate outflow),flap failure,and salvage success rate.We hope that it will provide a theoretical basis for the selection of the appropriate surgical approach in clinical.Methods1 Search strategyThe Pub Med and Embase electronic databases were searched for studies published before February 2020.2 Ducuments ScreeningThe inclusion criteria were as follows:1.Use of an RFFF for reconstruction in patients with head and neck tumors.2.Use of an RFFF with a single venous anastomosis,with a detailed comparison of the superficial and deep venous systems.3.Outcome indicators included the following:vascular compromise;flap failure;rate of salvage success.The rate of salvage success was determined as follows:the number of successful flaps that required re-exploration due to venous compromise when the superficial venous system or the deep venous system was used as the original venous anastomosis.Studies that assessed one of the outcome indicators listed above were included in the meta-analysis.The exclusion criteria were as follows:autopsy,reviews,case study,animal experiment,or meeting report.3 Data ExtractionThe data were extracted independently by two researchers who read the abstract and the full text to identify studies that fulfilled the inclusion criteria.Any disagreements between the researchers were settled by discussion.4 Quality AssessmentStudy quality was assessed with the Newcastle–Ottawa Scale(NOS).5 Statistical AnalysisA meta-analysis was performed with Review Manager,version 5.2,and STATA SE,version 12.0.X~2 and I~2statistics were used to evaluate inter-group heterogeneity,and these values were reported in terms of degrees of freedom(df).Binary outcomes(venous compromise,flap failure,and salvage success)were expressed as odds ratios(OR)with 95%confidence intervals(CI).Begg’s test and a funnel plot analysis were used to detect publication bias.Results1 Literature search and study characteristicsTwo hundred ninety-three relevant studies were found by searching the Pub Med and Embase databases,all of which were imported into Endnote x8software.After reviewing the titles and abstracts,43 studies were selected for in-depth reading of the full text.In the end,six studies fulfilled the criteria and were included in the meta-analysis.2 Venous compromiseThe results showed that venous compromise was more common in the superficial system than in the deep system(OR=2.29,95%CI:1.36-3.86,P=0.002),and there was no significant heterogeneity among studies(X~2=4.66,df=3,P=0.20,I~2=36%).Otherwise,no publication bias was detected(Begg’s test,P=0.149).2.1 Inadequate outflowThe superficial system had a significantly higher risk of inadequate outflow than the deep system(OR=3.02,95%CI:1.37-6.64,P=0.006),and there was no significant heterogeneity between studies(X~2=0.92,df=1,P=0.34,I~2=0%).2.2 Venous thrombosisPooling of the data revealed no significant difference between the superficial and deep systems(OR=0.92,95%CI:0.35-2.43,P=0.87),and there was no significant heterogeneity between studies(X~2=1.39,df=1,P=0.24,I~2=28%).3 Flap failureStatistical analysis showed no significant difference between groups(OR=0.30,95%CI:0.04-2.48,P=0.27),and there was no significant heterogeneity between studies(X~2=0.38,df=1,P=0.54,I~2=0%).4 Salvage success rateThe rate of salvage success was significantly higher for the superficial system than the deep system(OR=8.19,95%CI:1.75-38.3,P=0.008),and there was no significant heterogeneity between studies(X~2=0.09,df=1,P=0.77,I~2=0%).Conclusion Although the deep system had a lower risk of venous compromise,the evidence provided by our meta-analysis was insufficient to determine which type of drainage system was more suitable for single venous anastomosis in RFFF.Future studies with a large number of patients and more outcome indicators are required,and randomized trials are needed to confirm and update the findings of our study.