Take-back Operation Research Articles

An Institutional Analysis of Early Postoperative Free Tissue Transfer Takeback Procedures.

Postoperative free tissue transfer reexploration procedures are relatively infrequent but associated with increased overall failure rates. This study examines the differences between flaps requiring takeback versus no takeback, as well as trends in reexploration techniques that may increase the odds of successful salvage. A retrospective review was conducted on all free tissue transfers performed at our institution from 2011 to 2022. Patients who underwent flap reexploration within 30 days of the original procedure were compared with a randomly selected control group who underwent free flap procedures without reexploration (1:2 cases to controls). Univariate and multivariate logistic regression analyses were performed. From 1,213 free tissue transfers performed in the study period, 187 patients were included in the analysis. Of the total flaps performed, 62 (0.05%) required takeback, and 125 were randomly selected as a control group. Free flap indication, flap type, reconstruction location, and number of venous anastomoses differed significantly between the two groups. Among the reexplored flaps, 8 (4.3% of the total) had a subsequent failure while 54 (87.10%) were salvaged, with significant differences in cause of initial flap failure, affected vessel type, and salvage technique. Free tissue transfers least prone to reexploration involved breast reconstruction in patients without predisposition to hypercoagulability or reconstruction history. When takeback operations were required, salvage was more likely in those without microvascular compromise or with an isolated venous injury who required a single exploratory operation.

Delayed versus early hepatic resection among patients with severe traumatic liver injuries undergoing damage control laparotomy

IntroductionWe aimed to assess the effect of time to hepatic resection on the outcomes of patients with high-grade liver injuries who underwent damage control laparotomy (DCL). MethodsThis is a 4-year (2017–2020) analysis of the ACS-TQIP. Adult trauma patients with severe liver injuries (AAST-OIS grade ​≥ ​III) who underwent DCL and hepatic resection were included. We excluded patients with early mortality (<24 ​h). Patients were stratified into those who received hepatic resection within the initial operation (Early) and take-back operation (Delayed). ResultsOf 914 patients identified, 29% had a delayed hepatic resection. On multivariable regression analyses, although delayed resection was not associated with mortality (aOR:1.060,95%CI[0.57–1.97],p ​= ​0.854), it was associated with higher complications (aOR:1.842,95%CI[1.38–2.46],p ​< ​0.001), and longer hospital (β: +0.129, 95%CI[0.04–0.22],p ​= ​0.005) and ICU (β:+0.198,95%CI[0.14–0.25],p ​< ​0.001) LOS, compared to the early resection. ConclusionDelayed hepatic resection was associated with higher adjusted odds of major complications and longer hospital and ICU LOS, however, no difference in mortality, compared to early resection.

The impact of COVID-19 pandemic on free tissue transfer outcomes: A NSQIP analysis

The COVID-19 pandemic significantly impacted hospital resources and patient care, although its effect on free tissue transfer procedures is poorly understood. We conducted the current study to investigate the potential impact of COVID-19 and its accompanying system shut-downs on the surgical outcomes of patients undergoing free flap procedures. Patients undergoing free tissue transfer procedures were identified from the National Surgical Quality Improvement Program (NSQIP) database from 2016 to 2020. We used 2016-2019 as baseline (pre-pandemic) data to compare with 2020 (peri-pandemic). We divided the patients into the following 3 groups: all patients undergoing free tissue transfer, breast reconstruction free tissue transfer, and non-breast free tissue transfer cases. Outcomes of interest included patient morbidity/mortality, time to surgery, time to takeback, and length of hospital stay. We used Pearson's chi-square and Fisher's exact tests to assess categorical variables. Wilcoxon's ranked sign tests and ANOVA tests were used for non-parametric and parametric continuous variables, respectively. Significance was set at alpha <0.05. When comparing peri-pandemic to pre-pandemic rates, patient morbidity and mortality and unplanned primary or secondary takeback operations were both significantly higher in all 3 groups peri-pandemic. Median time to primary or secondary takeback operation was also significantly greater peri-pandemic. Patients undergoing flap procedures peri-pandemic had an overall increase in median morbidity and mortality, unplanned primary or secondary takebacks, and median number of days to takebacks compared to the pre-pandemic period. This is concerning given that any future protocols instituted can have detrimental effects on patients who receive a free tissue transfer procedure.

Outcomes of Free Muscle Flaps versus Free Fasciocutaneous Flaps for Lower Limb Reconstruction following Trauma: A Systematic Review and Meta-Analysis.

Free flap reconstruction of the lower limb following trauma often suffers higher complication rates than other areas of the body. The choice of muscle or fasciocutaneous free flap is an area of active debate. A systematic review of EMBASE, MEDLINE, PubMed, and Cochrane Register from inception to April 1, 2022 was performed. Articles were assessed using the methodological index for non-randomized studies instrument. The primary outcome was to assess and compare the major surgical outcomes of partial or total flap failure, reoperation, and amputation rates. Seventeen studies were included. All studies were retrospective in nature, of level three evidence, and published between 1986 and 2021. The most common muscle and fasciocutaneous free flaps used were latissimus dorsi flap (38.1%) and anterolateral thigh (ALT) flap (64.8%), respectively. Meta-analysis found no significance difference in rates of total flap failure, takeback operations, or limb salvage, whereas partial flap failure rate was significantly lower for fasciocutaneous flaps. The majority of studies found no significant difference in complication rates, osteomyelitis, time to fracture union, or time to functional recovery. Most, 82.4% (14/17), of the included studies were of high methodological quality. The rate of total flap failure, reoperation, or limb salvage is not significantly different between muscle and fasciocutaneous free flaps after lower limb reconstruction following trauma. Partial flap failure rates appear to be lower with fasciocutaneous free flaps. Outcomes traditionally thought to be managed better with muscle free flaps, such as osteomyelitis and rates of fracture union, were comparable.

Traffic modelling of an integrated 5G/Wi-Fi network with generally distributed user-dwell times

A traffic modelling method is proposed for an integrated 5G/Wi-Fi network with generally distributed user-dwell times. The Wi-Fi traffic can move flexibly between 5G cells and Wi-Fi cells through overflow, vertical handoff, horizontal handoff, and take-back operations. Various user dwell times are modelled by general distributions and the channel holding times are derived in terms of the Laplace transforms of the dwell times. The various arrival rates and related performance measures are derived through an algorithm of fixed-point equations. Multi-dimensional Markov processes are used to model the Wi-Fi traffic and 5G traffic and derive the steady-state probabilities through stationary symmetric queues. The traffic modelling method is applicable to the next generation of cellular systems integrated with other types of networks such as sensor networks, intelligent vehicle networks and Internet of Things applications.

Traffic modelling of an integrated 5G/Wi-Fi network with generally distributed user-dwell times

A traffic modelling method is proposed for an integrated 5G/Wi-Fi network with generally distributed user-dwell times. The Wi-Fi traffic can move flexibly between 5G cells and Wi-Fi cells through overflow, vertical handoff, horizontal handoff, and take-back operations. Various user dwell times are modelled by general distributions and the channel holding times are derived in terms of the Laplace transforms of the dwell times. The various arrival rates and related performance measures are derived through an algorithm of fixed-point equations. Multi-dimensional Markov processes are used to model the Wi-Fi traffic and 5G traffic and derive the steady-state probabilities through stationary symmetric queues. The traffic modelling method is applicable to the next generation of cellular systems integrated with other types of networks such as sensor networks, intelligent vehicle networks and Internet of Things applications.

Owning or Outsourcing? Strategic Choice on Take-Back Operations for Third-Party Remanufacturing

Despite the remanufacturing process having demonstrated economic, social, and environmental benefits, many original equipment manufacturers (OEMs) have not engaged in the remanufacturing process themselves, as they often outsource it to a third party. In practice, such outsourcing usually involves two different options/modes for OEMs with consideration of take-back operations: (1) owning the reverse channel and collecting cores directly (Model D) or (2) outsourcing these operations to a third-party remanufacturer (TPR) and collecting cores indirectly (Model I). However, this raises the important question of whether OEMs should also outsource their reverse channels to third-party remanufacturers when outsourcing remanufacturing. Furthermore, there needs to be an investigation of which method is more beneficial in terms of economic, social, and environmental outcomes. This paper uses modelling to investigate the costs and benefits of these options in terms of sustainability. We found that, compared to Model I, the OEM conducting take-back operations itself can achieve the overall better outcomes for all economic, social, and environmental situations.

Management of Destructive Colon Injuries after Damage Control Surgery.

After the World War II, fecal diversion became the standard of care for colon injuries, although medical, logistic, and technical advancements have challenged this approach. Damage control surgery serves to temporize immediately life-threatening conditions, and definitive management of destructive colon injuries is delayed until after appropriate resuscitation. The bowel can be left in discontinuity for up to 3 days before edema ensues, but the optimal repair window remains within 12 to 48 hours. Delayed anastomosis performed at the take-back operation or stoma formation has been reported with variable results. Studies have revealed good outcomes in those undergoing anastomosis after damage control surgery; however, they point to a subgroup of trauma patients considered to be "high risk" that may benefit from fecal diversion. Risk factors influencing morbidity and mortality rates include hypotension, massive transfusion, the degree of intra-abdominal contamination, associated organ injuries, shock, left-sided colon injury, and multiple comorbid conditions. Patients who are not suitable for anastomosis by 36 hours after damage control may be best managed with a diverting stoma. Failures are more likely related to ongoing instability, and the management strategy of colorectal injury should be based mainly on the patient's overall condition.

Free tissue transfer for necrotizing fasciitis reconstruction: A case series

BackgroundNecrotizing fasciitis (NF) is a life-threatening infection requiring extensive debridement that may necessitate amputation. Free tissue transfer (FTT) is an option for reconstruction in difficult cases. Currently, only case reports have described FTT in the setting of NF, and comprehensive evidence on flap outcomes is lacking. The present study characterizes outcomes in patients with FTT following NF. MethodsAll patients admitted with NF between January 1, 2005 and December 31, 2011 to our level 1 burns/trauma referral center were retrospectively reviewed. ResultsNo significant difference was found in patient demographics between FTT (n=12) and no FTT (n=212). Both groups had the same number of operations, same length of ICU stay, and length of hospitalization. The flaps used were 10 anterolateral thigh, 1 latissimus dorsi and 1 radial forearm. Recipient sites included: upper extremities (6), lower extremities (4), head/neck (1), and genitalia (1). No flap failures and no take-back operations were required. Upper extremities comprised 58.3% of FTT patients compared to 18.9% (p=0.004) in non-FTT patients. Flap operations occurred a mean of 11.6days post-admission with 1.1 operations prior to FTT. Mean FTT size was 213cm2. Flap complications included seroma (n=1), hematoma (n=1). Donor site complications included hematoma (n=1), exposed tendon (n=1) and necrosis (n=1). ConclusionsThis study demonstrates that FTT provides a promising reconstructive option in the setting of NF without adversely affecting patient outcome.

Redistributing stock in library systems with a depot

Public library organizations often utilize depots for carrying out shipments to libraries in case of stock-outs and for storing low demand rental items at low cost. Similar systems may be employed by rental companies for other rental products such as tools, DVDs, and jewelry. Since shipments deplete the depot’s inventory, stock must be taken back from the libraries in order to deal with future shipment requests. These shipment and take-back operations are carried out periodically, e.g. daily or weekly. This work focuses on optimizing the decisions for shipments and take-backs. We model the system by means of a Markov decision process and investigate its optimal policy for various problem instances. For the take-back decision, we distinguish between so-called threshold, reactive, and preventive take-backs. We use the insights from the MDP to develop a three-phase take-back heuristic. In experiments, our heuristic performs within 1% on average from the optimal solution. For settings with a large number of libraries, it is shown that an acceptable performance can be achieved by setting a base-stock level at the depot and taking back sufficient stock from the libraries to achieve this level.

Outcomes of Take-Back Operations in Breast Reconstruction with Free Lower Abdominal Flaps.

BackgroundMicrovascular complications after free-flap breast reconstructions are potentially devastating problems that can increase patient morbidity and lead to flap loss. To date, no comprehensive study has examined the rates of salvage and the methods of microvascular revision in breast reconstruction. We reviewed the treatment of microvascular complications of free-flap breast reconstruction procedures over a seven-year period.MethodsA retrospective review of all patients who underwent microvascular breast reconstruction at our institution between April 2006 and December 2013 was conducted. Based on their surgical records, all patients who required emergency re-exploration were identified, the rate of flap salvage was determined, the factors associated with flap salvage were evaluated, and the causes and methods of revision were reviewed.ResultsDuring the review period, 605 breast reconstruction procedures with a free lower abdominal flap were performed. Seventeen of these flaps were compromised by microvascular complications, and three flaps were lost. The overall salvage rate was 82.35%. No significant differences between the salvaged group and the failed group were observed with regard to age, BMI, axillary dissection, number of anastomotic arteries and veins, recipient vessel types, or use of the superficial inferior epigastric vein in the revision operation. Successful salvage of the flap was associated with a shorter time period between recognizing the signs of flap compromise and the take-back operation.ConclusionsThe salvage rate of compromised lower abdominal flaps was high enough to warrant attempting re-exploration. Immediate intervention after the onset of flap compromise signs is as important as vigilant postoperative monitoring.

Time to first take-back operation predicts successful primary fascial closure in patients undergoing damage control laparotomy

Failure to achieve primary fascial closure (PFC) after damage control laparotomy is costly and carries great morbidity. We hypothesized that time from the initial laparotomy to the first take-back operation would be predictive of successful PFC. Trauma patients managed with open abdominal techniques after damage control laparotomy were prospectively followed at 14 Level 1 trauma centers during a 2-year period. Time to the first take-back was evaluated as a predictor of PFC using hierarchical multivariate logistic regression analysis. A total of 499 patients underwent damage control laparotomy and were included in this analysis. PFC was achieved in 327 (65.5%) patients. Median time to the first take-back operation was 36 hours (interquartile range 24-48). After we adjusted for patient demographics, resuscitation volumes, and operative characteristics, increasing time to the first take-back was associated with a decreased likelihood of PFC. Specifically, each hour delay in return to the operating room (24 hours after initial laparotomy) was associated with a 1.1% decrease in the odds of PFC (odds ratio 0.989; 95% confidence interval 0.978-0.999; P = .045). In addition, there was a trend towards increased intra-abdominal complications in patients returning after 48 hours (odds ratio 1.80; 95% confidence interval 1.00-3.25; P = .05). Data from this prospective, multicenter study demonstrate that delays in returning to the operating room after damage control laparotomy are associated with reductions in PFC. These findings suggest that emphasis should be placed on returning to the operating room within 24 hours after the initial laparotomy if possible (and no later than 48 hours).

Recipient Vessel Selection in Immediate Breast Reconstruction with Free Abdominal Tissue Transfer after Nipple-Sparing Mastectomy

BackgroundNipple-sparing mastectomy (NSM) is gaining popularity due to its superior aesthetic results. When reconstructing the breast with free abdominal tissue transfer, we must readdress the recipient vessel, because NSM can cause difficulty in access to the chest vessel.MethodsBetween June 2006 and March 2011, a total of 92 women underwent NSM with free abdominal tissue transfer. A lateral oblique incision was used for the nipple-sparing mastectomy. For recipient vessels, the internal mammary vessels were chosen if the mastectomy flap did not block access to the vessels. If it did, the thoracodorsal vessels were used. Age, degree of breast ptosis, weight of the mastectomy specimen, and related complications of the internal mammary vessel group and the thoracodorsal vessel group were compared.ResultsThoracodorsal vessels were used as recipient vessels in 59 cases, and internal mammary vessels in 33 cases including 4 cases with perforators of the internal mammary vessels. Breast reconstruction was successful in all cases except one case involving a total flap failure, which was replaced by a silicone gel implant. The internal mammary group and the thoracodorsal group were similar in terms of age, height, breast weight, and degree of ptosis. The flap related complications such as flap loss and take-back operation rates were not significantly different between the two groups. The rate of nipple necrosis was higher in the internal mammary group.ConclusionsThe thoracodorsal vessels could produce comparable outcomes in breast reconstruction after nipple-sparing mastectomies. If access to internal mammary vessels is difficult, the thoracodorsal vessel can be a better choice.

Simultaneous Selective Disassembly and End-of-Life Decision Making for Multiple Products That Share Disassembly Operations

Environmental protection legislation, consumer interest in “green” products, a trend toward corporate responsibility and recognition of the potential profitability of salvaging operations, has resulted in increased interest in product take back. However, the cost effectiveness of product take-back operations is hampered by many factors, including the high cost of disassembly and a widely varying feedstock of dissimilar products. Two types of decisions must be made, how to carry out the disassembly process in the most efficient manner to “mine” the value-added that is still embedded in the product, and then how to best utilize that value-added once it is recovered. This paper presents a method for making those decisions. The concept of a transition matrix is integrated with mixed integer linear programming to determine the extent to which products should be disassembled and simultaneously determine the optimal end-of-life (EOL) strategy for each resultant component or subassembly. The main contribution of this paper is the simultaneous consideration of selective disassembly, multiple products, and the value added that remains in each component or subassembly. Shared disassembly operations and capacity limits are considered. An example using two cell phone products illustrates application of the model. The obtained results demonstrate the most economical level of disassembly for each cell phone and the best EOL options for each resultant module. In addition, the cell phone example shows that sharing disassembly operations between different products makes disassembly more cost effective compared with the case in which each product is disassembled separately.