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1、A commentary by Thomas J.Fischer,MD,FAOA,is linked to the online version of thisarticle at jbjs.org.Patency Test of Vascular Anastomosis with Assistanceof High-Speed Video Recording in Digit ReplantationHongyi Zhu,MD,Xiaozhong Zhu,MD,Changqing Zhang,MD,and Xianyou Zheng,MDInvestigation performed at
2、the Department of Orthopaedic Surgery,Shanghai Jiaotong University Affiliated Sixth Peoples Hospital,Shanghai,PeoplesRepublic of ChinaBackground:Quality assessment of vascular anastomosis primarily depends on the experience of the treating surgeon.This highlights the need for an objective index.The
3、main goal of our study was to establish a method of assessing thequality of vascular anastomosis in digit replantation.Methods:A total of 182 digits from 141 patients were included in this study.The patients underwent replantation ofcompletely amputated digits between June 1,2015,and February 1,2017
4、.Patency tests of arterial and venousanastomoses were conducted for each replantation and recorded on digital video at 1,000 frames per second.Wedivided the study into 2 phases.In phase I(103 digits from 80 patients),we investigated whether the refilling velocityratio(RVR)was associated with replant
5、ation failure.In phase II(79 digits from 61 patients),we adopted the RVR as aguiding parameter during surgery and compared the replantation success rate with that of the historical control ofphase I.Results:In phase I,ischemia time(12 hours),arterial RVR(0.4),and venous RVR sum(80%3,4.Arterial throm
6、bosis and venous congestion are theleading causes of replantation failure5,6.The surgical techniques used,especially vascular anas-tomotic techniques,are the most important factors thatdetermine the success of a replantation attempt.Anastomoticpatency is usually assessed with a patency test.This inv
7、olvesfirst emptying a vascular segment with the use of 2 micro-forceps,removing the occluding forceps,and then estimatingrefilling velocity1.High-quality vascular anastomosis is indi-cated by a“swift”refill.However,an explicit criterion of theacceptable refilling velocity is not available,because sl
8、ight dif-ferences in refilling velocity cannot be distinguished with thenaked eye.We hypothesized that slight differences in refilling ve-locity might be associated with the success rate of digitreplantation and that these differences could be distinguishedwith the assistance of video data acquired
9、with a high-speeddigital camera.In this study,we determined the lowest limit ofacceptable refilling velocity(phase I).We then adopted thisrefilling velocity as a guiding parameter during subsequentsurgeries and compared the replantation success rate with thatof the historical control rate achieved i
10、n phase I.Disclosure:This study was supported by the National Natural Science Foundation of China(81371965),the Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant(20161429),and the Shanghai Pujiang Program(16PJD035).The Disclosure of Potential Conflicts of Interest formsare prov
11、ided with the online version of the article(http:/ OFBONE ANDJOINTSURGERY,INCORPORATEDJ Bone Joint Surg Am.2018;100:729-34dhttp:/dx.doi.org/10.2106/JBJS.17.00494Materials and MethodsThis study was approved by the Ethics Committee ofShanghai Jiaotong University Affiliated Sixth PeoplesHospital.Inform
12、ed consent was obtained from all participantsin accordance with the Declaration of Helsinki.This study wasdivided into 2 phases:phase I was observational,and phase IIinvolved test-guided replantations.Subject DemographicsWe identified all patients who experienced a complete ampu-tation and underwent
13、 digit replantation at our institutionbetween June 1,2015,and February 1,2017.“Completeamputation”wasdefinedascompleteseparationofallpartsofadigit without any bridging tissues.The success rate of digit replantation is affected by age,smoking status,amputation level,cause of injury,and warmischemia t
14、ime7-9.Thus,these parameters were recorded.Thelevel of amputation was classified according to the Tamaiclassification system10.The mechanisms of injury were classi-fied as blade,saw,crush,or avulsion.Patients with any of the following criteria were excluded:single or multiple organ failure,periphera
15、l arterial disease,additional injury to the artery in the ipsilateral arm or forearm,or an age of 18 years.The standard protocol for the preservation of an am-putated digit is to wrap it in gauze moistened with salinesolution and then place it on ice in a watertight bag.In mostcases,the amputated di
16、gits were not correctly preserved beforeFig.1One of the cameras used to record segment refilling during the patencytests,the Sony RX100 V,shown here with a close-up lens affixed.Fig.2Vascular segment measured on video frames for calculating refillingvelocity.The length of the empty segment(indicated
17、 by the line showingempty length)was the distance used in the velocity calculation.This dis-tance was converted to a value relative to the proximal vessel diameter(orthogonalline).Inthiscase,thevaluewas3.01,indicatingthattheemptysegment length was 3.01 times the proximal vessel diameter.TABLE I Anal
18、ysis of Demographic Characteristics,Risk Factors,and RVRs by Outcome in 82 Cases with Single ArterialAnastomosis*Success(N=72)Failure(N=10)P ValueAge0.17445 yr45(92)4(8)45 yr27(82)6(18)Sex0.978Male65(88)9(12)Female7(88)1(13)Mechanismof injury0.341Blade18(100)0(0)Saw30(86)5(14)Crush15(83)3(17)Avulsio
19、n9(82)2(18)Tamai level0.455III28(85)5(15)IV36(92)3(8)V8(80)2(20)Ischemia time0.00312 hr2(40)3(60)Smokingstatus0.153Yes20(80)5(20)No52(91)5(9)Arterial RVR0.0010.49(56)7(44)0.463(95)3(5)Sum of venousRVRs0.0041.011(65)6(35)1.061(94)4(6)*The values are given as the number of digits,with the percentagefo
20、r the given row in parentheses.RVR=refilling velocity ratio.730THEJOURNAL OFBONE&JOINTSURGERYdJBJS.ORGVOLUME100-AdNUMBER9dMAY2,2018PATENCYTEST OFVASCULARANASTOMOSIS WITHHIGH-SPEEDVIDEORECORDINGarrival at our hospital;we encountered only 3 patients withcorrectly preserved digits during the study peri
21、od.Therefore,we also excluded the digits that had been well-preserved afteramputation to eliminate confounding effects by those cases.For the purpose of the study,we included only digitssevered at Tamai level III,IV,or V;in cases of Tamai level-I andII injuries,veins may not be available for repair.
22、Bleeding fromveins and improvements in color and warmth of the replantwere observed after arterial anastomosis in all included cases.Cases in which these criteria were not observed were excludedfrom the study.Phase ItookplacefromJune1,2015,toJune 1,2016,andphase II took place from June 2,2016,to Feb
23、ruary 1,2017.Intotal,103 digits(80 patients)were included in phase I,and 79digits(61 patients)were included in phase II.Video TechniqueThe method of the patency test was identical for an artery orvein;the test was conducted on every repaired vessel.Briefly,avascular segment was emptied with the use
24、of 2 microforceps,the occluding forceps were then removed,and the refilling ofthe segment was video recorded.The patency tests wereconducted on vascular segments proximal and distal to theanastomosis.Videos were recorded at 1,000 frames per sec-ond(FPS)using an RX100 IV or RX100 V digital camera(Son
25、y),and various close-up lenses were used for magnifi-cation(Fig.1).A representative slow-motion video is pre-sented(Video 1).The video was first converted to serialimages at the original frame rate.The absolute length of theemptied vascular segment was difficult to measure during thepatency test.In
26、addition,the proximal and distal tests for anindividual vessel were occasionally recorded as 2 separatevideos because of the limited recording period of 1,000 FPS(4 seconds for the RX100 IVand 6 seconds for the RX100 V).Therefore,we first standardized the length of the emptysegment according to the
27、proximal vessel diameter(Fig.2).Further analyses were based on the length relative to theproximal vessel diameter.The time points of the start and end of refilling weredetermined by observing the images in consecutive order(seeAppendix).The refilling time was determined by the numberof frames betwee
28、n the start and end points,with each framemeasuring 1/1,000 second.The refilling velocity was calculatedaccording to the following formula:refilling velocity=empty lengthrefilling time:The refilling velocity ratio(RVR)for arteries was calculatedaccording to the following formula:arterial RVR=distal
29、refilling velocityproximal refilling velocity:The RVR for veins was calculated according to the followingformula:venous RVR=proximal refilling velocitydistal refilling velocity:The patency tests were performed twice to calculate an averageRVR.Replantation TechniqueAll included patients were initiall
30、y evaluated in the emergencydepartment.The replantations in thisstudy were performed by 8attending hand surgeons.Irrigation and debridement was firstconducted.AllfractureswerethenstabilizedwithKirschnerwiresafter appropriate shortening.The nerves and tendons were allrepaired,if possible.In phase I,t
31、he number of veins repaired perreplanted digit ranged from 2 to 4.Whether double or singlearterial anastomosis was performed was determined on the basisof the treating surgeons discretion.In phase II,a test-guidedTABLE II Prognostic Testing of the Arterial RVR and Venous RVR Sum for Predicting Repla
32、ntation Failure*Positive ResultSensitivitySpecificityPPVNPVYouden IndexArterial RVRArterial RVR 0.470%88%44%95%0.58Venous RVR sumVenous RVR sum 1.060%85%35%94%0.45Arterial RVR 1 venousRVR sumArterial RVR 0.4 and venousRVR sum 1.030%99%75%90%0.29Either arterial RVR or venousRVR sumArterial RVR 0.4 or
33、 venousRVR sum 1.0100%74%34%100%0.74*Replantation failure is the“positive”outcome.RVR=refilling velocity ratio,PPV=positive predictive value,and NPV=negative predictive value.TABLE III Results of the High-Speed Camera-Assisted PatencyTests in Phases I and II*Phase I(N=103)Phase II(N=79)P Value1 arte
34、rialRVR of 0.483(81)75(95)0.005Venous RVRsum of 1.081(79)76(96)0.001*The values are given as the number of digits,with the percentagefor the indicated phase in parentheses.RVR=refillingvelocityratio.731THEJOURNAL OFBONE&JOINTSURGERYdJBJS.ORGVOLUME100-AdNUMBER9dMAY2,2018PATENCYTEST OFVASCULARANASTOMO
35、SIS WITHHIGH-SPEEDVIDEORECORDINGprotocolwasadoptedandthesuccessratewascomparedwiththehistoricalcontroldataobservedinphaseI.Briefly,1digitalarterywas repaired and the RVR was measured.If the RVR was 0.4,anastomosisoftheotherdigitalarterywasattempted,toachievearatio of no less than 0.4.After anastomos
36、is of the other digitalartery,the ratio was measured again.If the ratio was still 0.4,1 of the arteries was re-anastomosed.Additional veins wereanastomosed,ifpossible,untilthesumoftheRVRsofallrepairedveins(venous RVR sum)reached a value of no less than 1.0.Follow-upAll patients in this study had at
37、least 1 month of follow-up.Failure was defined as necrosis of the replanted finger,requiringrevision amputation or a flap to cover the bone.Statistical MethodsAll statistical analyses were conducted using SPSS for Windows(version 22.0;IBM).Significance was defined as a p value of0.05.Significant dif
38、ferences between groups for each noncon-tinuous variable were assessed using a Pearson chi-square test orFisher exact test(if the expected count was 5 for any contin-gency cell).Operative times were evaluated using 1-way analysisof variance(ANOVA).Receiver operating characteristic(ROC)teststodetermi
39、netheoptimalthresholdsforthearterialRVRandvenousRVRsumwereperformedusingSPSS.Allnumericaldataare presented as the mean and standard deviation,and all cate-gorical data are presented as the number and percentage.ResultsPhase IIntotal,103digitswereincludedinphaseI,and82digitswithsingle arterial anasto
40、mosis were analyzed to determine RVRgoals.ThearterialRVRrangedfrom0.22to0.92,andthevenousRVRsumrangedfrom0.71to3.77.WecalculatedanROCcurveto determine the optimal thresholds for the arterial RVR andvenous RVR sum to predict replantation outcome.The optimalthresholds were approximately 0.4 for arteri
41、al RVR and 1.0 forvenousRVRsum.Wethenconductedaunivariateanalysisofthedemographic characteristics,risk factors,and RVRs(Table I).Finally,we performed a prognostic test of the influence of thearterial RVR,the venous RVR sum,the arterial RVR in combi-nationwith the venous RVR sum,and either the arteri
42、al RVRorvenous RVR sum in predicting replantation failure(Table II).Phase IIOn the basis of the results of phase I,we set the arterial RVRgoal to 0.4 and the venous RVR sum goal to 1.0.In phase II(79 digits),we used the patency test assisted by the high-speedvideo data as a guide for vascular anasto
43、mosis.The final resultsof the patency tests in phases I and II are summarized inTable III.The goals we set were achievable in most cases.Specifically,14 digits presented with a low arterial RVR(0.4)and 15 digits presented with a low venous RVR sum(1.0)afterTABLE IV Demographic Characteristics,Risk F
44、actors,and Out-comes of the Two Phases*Phase I(N=103)Phase II(N=79)P ValueAge0.97145 years61(59)47(59)45 years42(41)32(41)Sex0.713Male93(90)70(89)Female10(10)9(11)Mechanism ofinjury0.940Blade23(22)16(20)Saw44(43)33(42)Crush22(21)16(20)Avulsion14(14)14(18)Tamai level0.848III41(40)29(37)IV49(48)38(48)
45、V13(13)12(15)Ischemia time0.91012 hr6(6)5(6)Smokingstatus0.685Yes31(30)26(33)No72(70)53(67)Outcome0.037Success90(87)76(96)Failure13(13)3(4)*The values are given as the number of digits,with the percentagefor the indicated phase in parentheses.TABLE V Comparison of Operative Time for a Single Digit*2
46、014 HistoricalControl(N=149)Phase I(N=103)Phase II(N=79)P ValueOperative time for 1 digit(hr)1.94 0.392.52 0.442.57 0.520.001*The values are given as the mean and standard deviation.732THEJOURNAL OFBONE&JOINTSURGERYdJBJS.ORGVOLUME100-AdNUMBER9dMAY2,2018PATENCYTEST OFVASCULARANASTOMOSIS WITHHIGH-SPEE
47、DVIDEORECORDINGinitial assessment.Repairing more veins was the only tacticemployed in this study to increase the venous RVR sum.Finally,12(80%)ofthe15digitsmetthevenousRVRsumcriterion.Forthe 14 digits with a low arterial RVR,the otherdigital artery wasrepaired,and the second anastomosis in 3 cases p
48、resented withanappropriatearterialRVR.Re-anastomosisof1arterywasthenconductedfortheremaining11digits,with7ultimatelymeetingthe criterion for arterial RVR.Compared with the historical control data from phase I(103 digits),the overall success rate significantly increased inphase II.Importantly,possibl
49、e confounding risk factors were notsignificantly different between the groups of patients in the 2phases(Table IV).We also compared operative times betweenphaseI,phaseII,andadditionalhistoricalcontroldatafrom2014.Operative times of phases I and II significantly increased com-pared with that noted fo
50、r the 2014 historical control(Table V).DiscussionThe hemodynamicchanges that occur after anastomosis aremajor contributors to thrombus formation.As a result,arterial and venous thrombosis may not be entirely prevent-able,even when antithrombotic therapy is administered topatients undergoing replanta