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Evaluation of a new chest tube removal protocol using digital air leak monitoring after lobectomy: a prospective randomised trial
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  Evaluation of a new chest tube removal protocol using digital air leakmonitoring after lobectomy: a prospective randomised trial Alessandro Brunelli*, Michele Salati, Majed Refai, Luca Di Nunzio,Francesco Xiume´, Armando Sabbatini Unit of Thoracic Surgery, Umberto I Regional Hospital, Ancona, Italy  Received 13 February 2009; received in revised form 13 February 2009; accepted 5 May 2009; Available online 8 July 2009 AbstractBackground:  The objective of this randomised trial was to assess the effectiveness of a new fast-track chest tube removal protocol takingadvantage of digital monitoring of air leak compared to a traditional protocol using visual and subjective assessment of air leak (bubbles). Methods:  One hundred and sixty-six patients submitted to pulmonary lobectomy for lung cancer were randomised in two groups with differentchest tube removal protocols: (1) in the new protocol, chest tube was removed based on digitally recorded measurements of air leak flow; (2) inthe traditional protocol, the chest tube removal was based on an instantaneous assessment of air leak during daily rounds. The two groups werecompared in terms of chest tube duration, hospital stay and costs.  Results:  The two groups were well matched for several preoperative andoperative variables. Compared to the traditional protocol, the new digital recording protocol showed mean reductions in chest tube duration(  p  = 0.0007),hospitalstay(  p  = 0.007)of0.9day,andameancostsavingof  s 476perpatient(  p  = 0.008).Inthenewchesttuberemovalprotocol,51% of patients had their chest tube removed by the second postoperative day versus only 12% of those in the traditional protocol.  Conclusions: The application of a chest tube removal protocol using a digital drainage unit featuring a continuous recording of air leak was safe and costeffective.Althoughfuturestudiesarewarrantedtoconfirmtheseresultsinothersettings,theuseofthisnewprotocolisnowroutinelyappliedinour practice. # 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved. Keywords:  Air leak; Chest tube; Pulmonary lobectomy; Postoperative stay; Lung cancer; Postoperative care 1. Introduction Financial restraints have led both administrators andphysicians to place increasing emphasis on fast-trackingthoracic surgical patients with the objective to cutpostoperative hospital costs and increase revenues.Implementing a fast-track protocol requires the standar-disation of safe pathways of care [1—3]. Despite the factthat the management of chest tubes is arguably one of themost critical aspects in fast-tracking lung resectionpatients [4], and valuable efforts have been made tostandardise it [5,6], the characteristics of the drainageunits used so far limited the reproducibility of theproposed algorithms.The recent introduction of new technologies allowing acontinuous monitoring and recording of air leak flow andintrapleural pressure [7,8] will contribute to improving thescientific standard of chest tube management and has led usto develop and test a new chest tube removal protocol withthe intent to streamline the postoperative stay of our lungresection patients.Therefore, the objective of this prospective randomisedstudy was to verify the cost effectiveness of a new fast-tracking chest tube removal protocol using a digital systemfeaturing a continuous recording of air leak andcompare ittocontrols managed with our traditional institutional chesttube removal protocol using instantaneous assessment(bubbling) of air leak on a traditional chest drainage unit. 2. Patients and methods All the patients who were submitted to pulmonarylobectomy for lung cancer at our institution from August2007 through December 2008 were prospectively enrolled inthe study. The study was approved by the local InstitutionalReview Board (IRB) and all patients gave their informedconsent for the study protocol.All patients undergoing pulmonary lobectomy during thestudyperiodwereinitiallyconsideredforstudy.Atotalof166patients were randomised in two groups. www.elsevier.com/locate/ejctsEuropean Journal of Cardio-thoracic Surgery 37 (2010) 56—60* Corresponding author. Address: Via S. Margherita 23, Ancona 60129, Italy.Tel.: +39 0715964439; fax: +39 0715964433. E-mail address:  alexit_2000@yahoo.com (A. Brunelli).1010-7940/$ — see front matter # 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.doi:10.1016/j.ejcts.2009.05.006  Group 1  ( 84 patients  ): A new chest drainage system wasapplied featuring a digital continuous recording of air leakand intrapleural pressure (DigiventTM, Millicore AB, Dan-deryd, Sweden). The system has two micro electronicmechanical system (MEMS) sensors, one for measuring flowand another for measuring pressure. A liquid crystal display(LCD) display is used to present measurement data at thebedside of the patient for clinical use. Pleural effusionthreshold for removal was 400 ml day  1 . By using the newdigital chest drainage system, the assessment of air leakrelied on recorded information. If the average air leak flowwas 0 ml min  1 during the last 6 h (the system can displayrecorded information on air leak flow during the last 1, 3 and6 h at the bedside of the patient), a chest X-ray was obtainedand, if the lung was deemed sufficiently expanded, the chesttube was removed. Moreover, based on previously publishedexperiences [9], in the presence of an average air leak flowlower than 15 ml min  1 during the last 6 h, a chest X-ray wasobtained, and if the lung was sufficiently expanded weperformed a provocative clamping for 12—24 h. After thatperiod,thechesttubewasre-openedforatleast1 handifnoactiveairleakwaspresentandthepleuralpressureremainedwithin negative values, the chest tube was removed. Group 2  ( 82 patients  ): Pleural effusion threshold forremoval was 400 ml day  1 . By using traditional chestdrainage units (Pleur Evac A-6002-08, Teleflex Inc., ResearchTriangle Park, NC, USA), the assessment of air leak relied onthe subjective instantaneous assessment of bubbling in thewater-seal column by making the patients perform repeatedforced expiratory efforts. If during morning or eveningrounds,noairleakwasdetectedinthisway,achestX-raywasobtained. The chest tube was removed if the lung wasdeemed sufficiently expanded at chest X-ray. In equivocalcases, the chest tube was clamped and then, if no signs orsymptoms of desaturation, dyspnoea or enlarging subcuta-neous emphysema ensued, removed 12 h later.The flow of patients in this study is shown in Fig. 1.There were three postoperative in-hospital deaths (onein the digital and two in the traditional group, respectively),and seven patients required a postoperative prolongedmechanical ventilation (two in the digital and five in thetraditional group, respectively). These patients wereexcluded from the analysis, leaving a total of 159 patientsfor the study (82 in group 1 and 77 in group 2, respectively).All patients in both groups were operated on by the samegroup of qualified thoracic surgeons in a single centre. Allpulmonary lobectomies were performed through a lateralmuscle-sparing, rib-sparing, intercostals nerve-sparing thor-acotomy [10]. Staplers were used to complete the fissuresand no sealants or pleural tents were used in this particularseries of patients. At the end of the procedure, two chesttubes (28 Fr in size) were positioned: one at the apex and theother at the base of the pleural cavity. These chest tubeswere left on suction (  15 cmH 2 O) until the morning of thefirst postoperative day. Alternate suction (  15 cmH 2 O duringnightandnosuctionduringtheday)wasappliedthereafterasperinstitutionalprotocol[11].Whenpleuraleffusionwaslessthan 400 ml day  1 the posterior chest tube was removed (if no air leak was exclusively present at this site). The last tubewas removed when no air leak was detected according toindividualgroupprotocols(seeabove).Chesttubedurationiscalculated based on the time of the last tube removed.Besides differences in chest tube removal protocols, thepostoperative treatment was standardised for all patientsand focussed on early mobilisation, respiratory and physicalrehabilitationandanti-thromboticprophylaxis.Thoracotomypain control was achieved by means of intravenous (IV)infusion of non-opiates titrated to reach a visual analoguescore of less than 4 (in a scale from 0 to 10), during the firstpostoperative 48—72 h.All patients were seen at our outpatient clinic 10—14 daysafter discharge, at which time an additional chest X-ray wasperformed. 2.1. Statistical analysis  This is a prospective randomised study. Simple unrest-ricted randomisation was used to allocate the patients in thetwo groups, by using a computerised numerical sequence.Randomisation and group allocation occurred before opera-tion. This was an ‘intention to treat’ analysis. No cross-overbetween groups occurred.The sample size of the study was set to obtain a statisticalpower of at least 0.9 for detecting an expected difference inpostoperative stay of at least 1 day between the groups witha two-tailed significance level of 0.05. Randomisation wasperformed followingtheConsolidatedStandardsofReportingTrials (CONSORT) criteria and guidelines [12] (Fig. 1). Air leak assessment was performed in both groups by one of the staff surgeons on duty during morning or evening rounds. For thenatureofthestudy,theobserverwasnotblindedtothegroupallocation. Numerical variables between the groups werecompared by means of the unpaired Student’s  t -test or theMann—Whitney test. The chi-square or Fisher’s exact testswere used for categorical variables as appropriate. NormaldistributionwasassessedbytheShapiro—Wilknormalitytest.The followingvariables were usedforcomparisonbetweengroups: age; gender; body mass index; forced expiratoryvolume (FEV 1 ); carbon monoxide diffusion capacity (D L CO);FEV 1 /forced volume vital capacity (FVC) ratio; diabetes;cardiac co-morbidity; side and site (upper vs lower) of resection; smoking history (pack—years); presence of pleuraladhesions; and length of stapled parenchyma (millimetres).  A. Brunelli et al./European Journal of Cardio-thoracic Surgery 37 (2010) 56—60   57Fig. 1. CONSORT flow-chart of patients enrolled in the study.  Pulmonary function tests were performed according toAmerican Thoracic Society criteria. D L CO was measured usingthe single-breath method. Results of spirometry werecollected after bronchodilator administration and wereexpressed as percentage of predicted for age, gender andheight (with the exception of FEV 1 /FVC ratio).Predicted postoperative values of FEV 1  and D L CO wereestimatedbytakingintoaccountthenumberofunobstructedsegments removed during operation (assessed by broncho-scopy and computed tomography (CT) scan findings). Aconcomitant cardiac disease was defined as follows: previouscardiac surgery, previous myocardial infarction, history of coronary artery disease, current treatment for hypertension,arrhythmia or cardiac failure. We computed the number of pack—years of smoking as the total number of years smoked,times the average number of cigarettes smoked per day,divided by 20.Presence of pleural adhesions was defined as presence of dense pleural adhesions occupying  > 30% of a lobe or morethan one lobe.Outcome variables were the following: chest tubeduration, length of postoperative hospital stay and post-operative costs.Fixed and variable costs were retrieved from thehospital’s accounting and pharmacy departments’ datasystems. Costs are expressed in euro ( s ).Fixed costs included capital, employee salaries, buildingmaintenance and utilities. Variable costs included patient-care supplies, food, radiographic film, laboratory reagentsand medications, with their delivery systems (such asintravenous catheters or bottles) and the cost of otherpostoperative therapeutic procedures such as cardioversion,bronchoscopy, blood transfusions, etc.All tests were two tailed with a significance level of 0.05and were performed using statistical software (Stata 8.2;StataCorp; College Station, TX, USA). 3. Results The two groups of patients were well matched for severalpreoperative and operative variables (Table 1).Cardiopulmonary complication rates were 17% (14 cases)and 14% (11 cases) in groups 1 and 2, respectively (  p  = 0.6).Prolonged air leaks ( > 5 days) occurred in five patients ingroup 1 and one in group 2, respectively (  p  = 0.2).Compared to the traditional protocol group, the one usingdigital continuous monitoring of air leak had a significantreduction in chest tube duration and postoperative stay of 0.9 day, and a significant s 476 mean cost saving per patient(Table 2).Forty-two patients (51%) in the digital group had theirchest tube removed by the second postoperative day versus 9(12%) in the traditional group (  p < 0.0001). Three patients inboth groups were discharged home with a portable chestdrainagesystemonpostoperativeday8.Forty-sevenpatients(59%) in the digital group were discharged home withoutchesttubebythe4thpostoperativedayversus22(30%)inthetraditional protocol group (  p  = 0.0002) (Figs. 2 and 3).In the digital group, eight patients underwent provo-cative clamping in the presence of an air leak lower than15 ml min  1 . In five patients (63%), the provocativeclamping was successful and chest tubes were removedafter 12—24 h without any complications. In threepatients, however, chest tubes needed to be re-openedfor enlarging subcutaneous emphysema, dyspnoea anddesaturation. In one of these patients, provocativeclamping was successfully repeated 8 h later; in the othertwo patients, chest tubes were removed once the air leakstopped 1 and 2 days later, respectively.Follow-up did not show any late pneumothorax or theneed for repositioning the chest tube in any of the patients inthis series in both groups.  A. Brunelli et al./European Journal of Cardio-thoracic Surgery 37 (2010) 56—60  58Table 1Comparison between the study groups in terms of preoperative and operative factors.Variables Digital (82 patients) Traditional (77 patients)  p  valueAge 66.1 (12.8) 67.3 (8.4) 0.8Male ( n , %) 57 (70%) 59 (77%) 0.3BMI (kg m  2 ) 25.7 (4.4) 27 (3.9) 0.1Pack—years 38.2 (32.4) 49 (40.3) 0.1FEV 1 % 84.8 (18.5) 86.1 (18.9) 0.6D L CO% 77.3 (19.7) 83 (20.8) 0.2FEV 1 /FVC ratio 0.69 (0.1) 0.7 (0.1) 0.6Cardiac disease ( n , %) 51 (62%) 36 (47%) 0.05Co-morbidity index 1.6 (1.5) 1.8 (1.8) 0.5Right side ( n , %) 41 (50%) 46 (60%) 0.2Upper resection ( n , %) 52 (63%) 52 (68%) 0.7Pleural adhesions ( n , %) 18 (22%) 15 (19%) 0.8Stapled parenchyma (mm) 140 (103) 120 (86) 0.3Air leak days 1.7 (3.6) 1.8 (4.3) 0.6Continuousvariablesareexpressedasmean  standarddeviationswith  p valuesfromStudent’s t -testorMann—Whitneytestasappropriate.Categoricalvariablesareexpressed as count (proportion) with  p  values from chi-square or Fishers exact tests, as appropriate. BMI: body mass index.Table 2Comparison between the two study groups in terms of duration of chest tube,hospital stay and costs.Variables Digital(82 patients)Traditional(77 patients)  p  valueChest tube (days) 4.0 (3.6) 4.9 (4) 0.0007Postoperative stay (days) 5.4 (2.2) 6.3 (2.9) 0.007Postoperative costs ( s ) 2391 (1581) 2867 (1800) 0.008Variables are expressed as mean  standard deviations with  p  values fromMann—Whitney test.  4. Discussion The increased pressure exerted by the managed caresystem on our profession demands the optimisation of pathways of care by standardising perioperative processes.Notonlyisthelengthofpostoperativestay(which,inpatientswho undergo pulmonary resection is mainly due to air leaks,chest tube removal, pain control and/or other complications)one of the most critical factors influencing in-hospitalexpenditures, but it is also the easiest parameter for thesurgeontounilaterallymodify.Inthiscontext,greatemphasishas been placed recently on fast-tracking thoracic surgicalpatients [3,4]. Patient-care protocols help standardise care,minimisethelengthofthelearningcurveforfast-trackingandavoidunnecessarycosts[1,2].Furthermore,theyallowfortheconsistentmanagementofthemainfactorsthatdelayhospitaldischarge after pulmonary resection. These include: chesttube management to expedite tube removal, air leakmanagement and pain control [4]. Fast-tracking requirespatients to be stratified according to their preoperative andoperativecharacteristicsandrelevantpostoperativeeventsortheir treatments objectively recorded in a standardisedfashioninordertostreamlinethepostoperativecourse.Chesttubemanagementisarguablyoneofthemostcriticalissuesinimplementing fast-tracking policy after lung resection.Several protocols have been published and used in clinicalpracticeintheattempttoprovidescientificguidanceinafieldthat is more influenced by subjective empirical experiencerather than byevidence-baseddata [5,6,11,13—15]. Althoughclinically important works have been published and tried tostratify the degree of air leak, these are limited by the scarcereproducibility of these classification systems as they lackobjective measurements through accurate and dedicatedinstruments [15,16].A digital chest drainage device was recently described,which is capable of continuously monitoring and recordingthe amount of air leak and the level of the intrapleuralpressure [7,8]. The system has the main advantage of providing objective and reproducible data, and decreasinginter-observer variability of air leak assessment, which maybe one of the principle factors in delaying chest tuberemoval [17]. Thus, we designed a fast-track chest tuberemoval protocol that could take advantage of thesefeatures and that could surmount some major limitationsof the traditional chest tube management, mostly based onsubjective instantaneous assessments of air leak duringdaily rounds. The new protocol is based on the recordedinformation stored in the controller unit of the digitaldrainage system and can be retrieved at the bedside of thepatient for clinical use. Since the volume of air leak canvary in the same patient depending on several factors(position, effort, status of lung parenchyma, etc.) and itspresence can be intermittent, we chose the average air leakflow in 6 h as the value on which to base the decision on howto manage the chest tube. We elected to remove the tube if the air leak was 0 ml min  1 during the last 6 h and to clampthe chest tube when the air leak was less than 15 ml min  1 during the last 6 h. This last cut-off for provocativeclamping was selected based on the information previouslypublished by Anegg and colleagues [9].By applying this protocol we were able to achieve twomain objectives:1. We demonstrated that objective information about airleak could be used to implement chest tube protocols inthe clinical practice in safe condition.2. Objective cut-offs are able to reduce the duration of chest tube in place and, hence, the postoperative stay, byminimising the inter-observer variability in the decision-making process of removing chest tubes [17].Although we demonstrated the efficacy of the digitaldevice compared to the traditional system, its use in all lungresectionpatientsremainsamatterofdebate. Currently,thecost of this system in Europe corresponds to approximately s 100—150 per unit. However, in those patients with an airleak at the end of operation or in those at higher risk todevelop a persistent air leak [6,18], its use may appear alogical choice. In fact, if it can decrease the length of stay byjust 1 day, it may more than pay for the cost differencecompared to the traditional chest drainage system [8].Although our study corroborates the findings of a recentrandomised trial comparing the same digital device with atraditional system [8], it differs in many aspects from  A. Brunelli et al./European Journal of Cardio-thoracic Surgery 37 (2010) 56—60   59Fig. 3. Postoperative stay in the two randomised groups.Fig. 2. Chest tube duration in the two randomised groups.  Cerfolio’s study: first, for the sake of homogeneity, onlypulmonary lobectomies for lung cancer were included as wewanted to focus on those resections with the highest risk of postoperative air leak. Second, the design of the study wasalso different, insofar as in the digital group we relied onrecorded information and not on digital instantaneousassessment of air leak for removing the tube, and nocross-over between the groups was allowed. Finally, socio-cultural, geographical, and structural factors may have beenalso different and may have had an influence on post-operative stay. Despite all these differences, both studieswere consistent in showing a statistically significant andclinically relevant reduction in hospital stay in those patientsusing the digital device.This study may have potential limitations.First, for its nature, the study was not blinded. The staff surgeon in duty was called to make a decision on whether toremove the chest tube based on information read from thetraditional or digital device and according to predeterminedprotocols.Second, early provocative clamping in the presence of anair leak was successful in five patients but failed in the otherthree, questioning the safety of the air leak cut-off valueproposed by previous investigation [9]. More studies areneeded to investigate the exact interplay between air flowand intrapleural dynamics that may affect the sealing of airleaksinselectedpatients.Itislikelythatdifferentthresholdswould be applicable for different types of patients ordifferent types of lung resections. The use of digital systemswith objective recorded information will assist in definingthese criteria.Finally, this study was designed to test the efficacy of anew chest tube removal protocol using digital information incomparison with our traditional institutional one using visualassessment of bubbles. It was not a study set to test thedigital apparatus in itself. Confirmation from other indepen-dent investigations using different protocols, different chesttube management (suction or water seal) and differentnumber of chest tubes (one instead of two) are warranted.In conclusion, we showed that the application of a newprotocol of chest tube removal taking advantage of objectiverecorded data about air leak was safe and feasible and wasable to reduce postoperative stay and costs compared topatients managed with our traditional chest tube removalprotocol based on instantaneous subjective assessment of airleaks.Theavailabilityofrecordeddataonairleakflowallowsa safer implementation offast-tracking policies of chest tuberemoval and provides the physician with objective data thatcan be stored in medical records or uploaded into databasesystems. This appears to be of great importance even in lightof the increasing emphasis placed on the patient’s safety,transparency andpublicaccountability.Futureinvestigationsare warranted to confirm these results in other settings andto verify whether these new technological devices mayhave a role not only for monitoring but also for treating airleaks by tailoring the suction level to optimise the balancebetween intrapleural pressure and air leak (active pleuralmanagement). Based on the results of the present study, westarted applying this new chest tube removal protocol to allour patients submitted to pulmonary lobectomy. Acknowledgement The authors are grateful to Millicore AB, Danderyd,Sweden for supporting this investigation by donating theirdigital chest drainage systems (DigiventTM). References [1] Zehr KJ, Dawson PB, Yang SC. Standardized clinical care pathways formajor thoracic cases reduce hospital costs. Ann Thorac Surg 1998;66:914—9.[2] Wright CD, Wain JC, Grillo HC. Pulmonary lobectomy patient care path-way: a model to control cost and maintain quality. Ann Thorac Surg1997;64:299—302.[3] Cerfolio RJ, Pickens A, Bass C, Katholi C. Fast-tracking pulmonary resec-tions. J Thorac Cardiovasc Surg 2001;122:318—24.[4] Bryant AS,Cerfolio RJ.Theinfluenceof preoperativeriskstratification onfast-tracking patients after pulmonary resection. Thorac Surg Clin2008;18:113—8.[5] CerfolioRJ,BryantAS.Resultsofaprospectivealgorithm toremovechesttubes after pulmonary resection with high output. J Thorac CardiovascSurg 2008;135:269—73.[6] Cerfolio RJ, Bass CS, Pask AH, Katholi CR. Predictors and treatment of persistent air leaks. Ann Thorac Surg 2002;73:1727—30.[7] Dernevik L, Belboul A, Radberg G. Initial experience with the world’s firstdigital drainage system. The benefits of recording air leaks with graphicrepresentation. Eur J Cardiothorac Surg 2007;31:209—13.[8] Cerfolio RJ, Bryant AS. The benefits of continuous and digital air leakassessment after elective pulmonary resection: a prospective study. AnnThorac Surg 2008;86:396—401.[9] Anegg U, Lindenmann J, Matzi V, Mujkic D, Maier A, Fritz L, Smolle-Ju¨ttner FM. AIRFIX W : the first digital postoperative chest tube airflow-metry—a novel method to quantify air leakage after lung resection. Eur JCardiothorac Surg 2006;29:867—72.[10] Cerfolio RJ, Bryant AS, Maniscalco LM. A nondivided intercostal muscleflapfurtherreducespainofthoracotomy:aprospectiverandomizedtrial.Ann Thorac Surg 2008;85:1901—7.[11] Brunelli A, Sabbatini A, Xiume´ F, Refai M, Salati M, Marasco R. Alternatesuction reduces prolonged air leak after pulmonary lobectomy: a ran-domized comparison versus water seal. Ann Thorac Surg 2005;80:1052—5.[12] Moher D, Shulz KF, Altman DG. The consort statement: revised recommen-dations for improving the quality of reports of parallel group randomizedtrials. BMC Med Res Methodol 2001;1:2. doi: 10.1186/1471-2288-1-2.[13] Cerfolio RJ, Bass CS, Katholi CR. Prospective randomized trial comparessuction versus water seal for air leaks. Ann Thorac Surg 2001;71:1613—7.[14] Marshall MB, Deeb ME, Bleier JI, Kucharczuk JC, Friedberg JS, Kaiser LR,Shrager JB. Suction vs. water seal after pulmonary resection: a rando-mized prospective study. Chest 2002;121:831—5.[15] Cerfolio RJ, Bryant AS, Singh S, Bass CS, Bartolucci AA. The managementof chest tubes in patients with a pneumothorax and an air leak afterpulmonary resection. Chest 2005;128(August (2)):816—20.[16] Cerfolio RJ. Chest tube management after pulmonary resection. ChestSurg Clin N Am 2002;12:507—27.[17] Varela G, Jimenez MF, Novoa NM, Aranda JL. Postoperative chest tubemanagement: measuring air leak using an electronic device decreasesvariability in the clinical practice. Eur J Cardiothorac Surg 2009;35:28—31.[18] Brunelli A, Monteverde M, Borri A, Salati M, Marasco RD, Fianchini A.Predictors of prolonged air leak after pulmonary lobectomy. Ann ThoracSurg 2004;77:1205—10.  A. Brunelli et al./European Journal of Cardio-thoracic Surgery 37 (2010) 56—60  60
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