Post operative monitoring of microvascular breast reconstructions using the implantable Cook–Swartz doppler system: A study of 145 probes & technical discussion

Adjunctive technologies in postoperative free-flap monitoring: a systematic review

Patent microvascular anastomoses are essential for successful free tissue transfer. Early accurate detection of microvascular compromise is required for flap salvage. Adjunctive monitoring techniques, in addition to clinical examination, are increasingly used to detect flap compromise. This systematic review synthesized and appraised the literature to determine the efficacy of different postoperative monitoring technologies. Rates of flap takeback, salvage, failure, and mean time to detection of microvascular compromise were extracted, synthesized, and reviewed. Twenty-two studies were included, comprising 6370 flaps. One thousand three hundred and ninety-five flaps were monitored with Cook Swartz Doppler (21.83%), 1417 flaps with tissue oximetry (22.24%), 291 with laser Doppler (4.56%), 175 with duplex echography (2.74%), 210 with indocyanine green (ICG) fluorescence (3.30%), 196 with Synovis flow coupler (3.07%), and 81 (1.27%) with light spectroscopy. The overall true positive rate for microvascular compromise in taken back flaps was 70.18%. Cook Swartz Doppler (n = 1391) had a true positive rate of 80.17% and 83.63% salvage rate and was associated with an overall 2.60% rate of flap failure. Tissue oximetry (n = 1417) had a true positive rate of 74.76% and a salvage rate of 88.62%. Laser Doppler, duplex echography, light spectroscopy, and Synovis flow coupler demonstrated true positive rates between 69.4% and 100% with salvage rates between 64% and 100%. Cook Swartz Doppler and tissue oximetry are associated with prompt identification of microvascular compromise and return to theatre. Alternative modalities, including near-infrared spectroscopy, laser Doppler, and duplex echography, show promise. Further well-designed randomised controlled trials (RCTs) appraising head-to-head efficacy are required to comparatively assess adjunctive technologies.

A Study Protocol Exploring the Role of an Implantable Doppler Probe in Kidney Transplantation: A Feasibility Randomized Controlled Trial with an Embedded Qualitative Study

OBJECTIVES

Vascular complications in kidney transplant surgery constitute one-third of early graft loss, which can be prevented by timely diagnosis of vascular compromise. A blood flow monitoring device may have a beneficial role in the early identification of graft hypoperfusion critical to reducing graft loss. This research protocol aims to evaluate the potential of an implantable Doppler probe as a blood flow monitoring device in kidney transplant recipients.

MATERIALS AND METHODS

The potential study will be a mixed methodology, 2-arm feasibility randomized controlled trial with an embedded qualitative study. For the trial, we will compare demographic characteristics and outcome measures of kidney transplant patients receiving implantable Doppler probe monitoring (intervention group, n = 30) with those having standard clinical care (control group). For the qualitative study, we will conduct semi-structured interviews with stakeholders (n = 12) recruited by purposive sampling to explore experiences of participants. All interviews will be audio recorded with verbatim transcription.

RESULTS

Our results will use the summarized quantitative data and descriptive statistics to determine differences between the groups. We will use CONSORT guidelines to determine the suitability of the research processes, availability of research resources, and potential challenges faced during the feasibility randomized controlled trial. We will use thematic analysis and NVivo software to analyze the acceptability of the intervention in clinical practice. We will compile the results according to the consolidated criteria for reporting qualitative research checklist.

CONCLUSIONS

The goal of this protocol is to determine the feasibility of an implantable Doppler probe monitoring device in kidney transplant recipients. The feasibility study will collect preliminary information, fill gaps in evidence, and test research processes for the pragmatic future randomized controlled trial. The template of this study is transferable to other transplant centers across the United Kingdom.

The Use of the Implantable Doppler Probe as a Blood Flow Monitoring Device in Clinical Settings: A Narrative Review of the Evidence

OBJECTIVES

In the past decade, the implantable Doppler probe has been studied widely as a blood flow-monitoring device in reconstructive and transplant surgical specialities. Its utility as an effective postoperative monitoring technique is still debatable, with no clear guidelines in clinical practice. Here, we mapped the current evidence on the usefulness of the implantable Doppler probe as a blood flow-monitoring device. The objective was to present an up-to-date assessment of the benefits and limitations of using implantable Doppler probes in clinical and experimental clinical settings.

MATERIALS AND METHODS

We conducted a literature search using the Cochrane Library and Healthcare Databases Advanced Search and using implantable Doppler probe, transplant, graft, and flap as key words. The search yielded 184 studies, with 73 studies included after exclusions. We evaluated, synthesized, and summarized the evidence from the studies in tabular form.

RESULTS

There is clinical equipoise regarding the effectiveness of implantable Doppler probe as a flow sensing technique. The main reason is the lack of information and gaps in the evidence regarding the benefits and limitations of using implantable Doppler probes in clinical practice.

CONCLUSIONS

The implantable Doppler probe has the potentialto be used as an adjunctpostoperativeblood flow-monitoring device. However, keeping in view of technical limitations, its signals should be interpreted alongside traditional clinical assessment techniques to determine the patency of microvascular anastomosis. Although evidence in this review will inform clinical practice in transplant and reconstructive surgical specialties, a prospective randomized controlled study with a larger patient cohort is required to evaluate the effectiveness of this probe in clinical settings.

Stacked deep inferior epigastric perforator with sequential lumbar artery perforator flaps for bilateral breast reconstruction: A case report

Breast size that can be reconstructed with a single flap is limited in thin patients who need bilateral autologous large-volume breast reconstruction. We present the case of a 39-year-old female with bilateral heterogeneous breast cancer. The patient underwent total mastectomy and radiation therapy on the left side and nipple sparing mastectomy on the right. We planned to use the stacked deep inferior epigastric perforator (DIEP) with sequential lumbar artery perforator (LAP) flaps because the patient's thigh was too thin and she refused using gluteal tissue. The flap was 10 cm wide at the abdomen, 5 cm wide at the waist, and 72 cm long overall. The DIEP and LAP flaps were harvested as one continuous flap and were folded onto each other to create a breast mound. The lumbar artery and vein were anastomosed to the distal stump of the deep inferior epigastric artery and vein (DIEA/V) intraflaps, and then, the proximal stump of the DIEA/V was anastomosed to the internal mammary artery and vein. The LAP flaps were placed deeply, whereas the DIEP flaps were placed superficially. Whole skin was de-epithelialized on the right side, and skin damaged by radiotherapy was released and replaced with abdominal skin on the left side. The flap survived fully, the shape of the reconstructed breasts was good, and the body line on the donor side was well maintained. We present the stacked DIEP with sequential LAP flaps as one of the options for bilateral breast reconstruction in thin patients with larger breast size.

Patient Management Strategies in Perioperative, Intraoperative, and Postoperative Period in Breast Reconstruction With DIEP-Flap: Clinical Recommendations

Background and Objective

Deep Inferior Epigastric Perforator (DIEP) flap is a tissue isolated from the skin and subcutaneous tissue of the lower abdomen or rectus muscle to foster breast reconstruction. There is limited information about DIEP-flap induced complications associated with breast reconstruction surgery.

Evidence

We conducted a systematic review of the published literature in the field of breast cancer reconstruction surgery. Information was gathered through internet resources such as PubMed, Medline, eMedicine, NLM, and ReleMed etc. The following key phrases were used for effective literature collection: “DIEP flap”, “Breast reconstruction”, “Patient management”, “Postoperative DIEP”, “Intraoperative anticoagulant therapy”, “Clinical recommendations”. A total of 106 research papers were retrieved pertaining to this systematic review.

Conclusion

A successful breast reconstruction with DIEP-flap without complications is the priority achievement for this surgical procedure. This study provides various evidence-based recommendations on patient management in the perioperative, intraoperative, and postoperative periods. The clinical recommendations provided in this review can benefit surgeons to execute breast reconstruction surgery with minimal postoperative complications. These recommendations are beneficial to improve clinical outcomes when performing surgery by minimizing complications in perioperative, intraoperative, and postoperative period.

Flexible Doppler ultrasound device for the monitoring of blood flow velocity

Thrombosis and restenosis after vascular reconstruction procedures may cause complications such as stroke, but a clinical means to continuously monitor vascular conditions is lacking. Conventional ultrasound probes are rigid, particularly for postoperative patients with fragile skin. Techniques based on photoplethysmography or thermal analysis provide only relative changes in flow volume and have a shallow detection depth. Here, we introduce a flexible Doppler ultrasound device for the continuous monitoring of the absolute velocity of blood flow in deeply embedded arteries based on the Doppler effect. The device is thin (1 mm), lightweight (0.75 g), and skin conforming. When the dual-beam Doppler method is used, the influence of the Doppler angle on the velocity measurement is avoided. Experimental studies on ultrasound phantoms and human subjects demonstrate accurate measurement of the flow velocity. The wearable Doppler device has the potential to enhance the quality of care of patients after reconstruction surgery.

Electroactive material-based biosensors for detection and drug delivery

Electroactive materials are employed at the interface of biology and electronics due to their advantageous intrinsic properties as soft organic electronics. We examine the most recent literature of electroactive material-based biosensors and their emerging role as theranostic devices for the delivery of therapeutic agents. We consider electroactive materials through the lens of smart drug delivery systems as materials that enable the release of therapeutic cargo in response to specific physiological and external stimuli and discuss the way these mechanisms are integrated into medical devices with examples of the latest advances. Studies that harness features unique to conductive polymers are emphasized; lastly, we highlight new perspectives and future research direction for this emerging technology and the challenges that remain to overcome.

Review of Flap Monitoring Technology in 2020

Advances in free flap reconstruction of complex head and neck defects have allowed for improved outcomes in the management of head and neck cancer. Technical refinements have decreased flap loss rate to less than 4%. However, the potential for flap failure exists at multiple levels, ranging from flap harvest and inset to pedicle lay and postoperative patient and positioning factors. While conventional methods of free flap monitoring (reliant on physical examination) remain the most frequently used, additional adjunctive methods have been developed. Herein we describe the various modalities of both invasive and noninvasive free flap monitoring available to date. Still, further prospective studies are needed to compare the various invasive and noninvasive technologies and to propel innovations to support the early recognition of vascular compromise with the goal of even greater rates of flap salvage.

Evaluation of implantable Doppler probe continuous monitoring of hepatic artery anastomosis after liver transplantation

Background

Thrombosis of hepatic artery anastomosis (HAT) after liver transplantation is a catastrophic and dreaded complication. Early identification of HAT can salvage the situation. To monitor the anastomosis, conventional daily transcutaneous Doppler is performed. However, it has disadvantages of being noncontinuous, operator-dependent and technically difficult. Implantable Doppler probes wrapped around the anastomosed vessel giving continuous signal may be an important tool; however, very few studies are performed to study its efficacy after intra-abdominal vascular anastomosis, and its role is not clearly established.

Methods

Patients who underwent deceased donor liver transplant surgery were part of the study. On hepatic arterial anastomosis, implantable Doppler probe was fixed for monitoring. Conventional daily transcutaneous Doppler was also performed and the results were compared.

Results

A total of 40 hepatic arterial anastomoses were studied. The incidence of HAT was 10.53%. For the implantable Doppler probe monitoring, sensitivity and negative predictive value was 100%, whereas specificity was 94.44% and positive predictive value was 66.66% with an overall accuracy of 95%. A mean of 10 h of lead time was gained by implantable Doppler probe monitoring.

Conclusion

Our study showed that there was high sensitivity and negative predictive value of implantable Doppler probe monitoring system, which makes it ideal for post-operative vascular anastomoses surveillance monitoring; however, abnormal positive finding on implantable Doppler probe monitoring needs to be confirmed by conventional transcutaneous Doppler. The implantable Doppler probe monitoring, because of its round the clock and continuous nature gives us a good lead time in identifying vascular complication, which translates into graft salvage and reduction in morbidity and mortality.

Monitoring Vascular Compromise Using Ultrasound After Free Tissue Transfer

OBJECTIVES

To report the clinical utility of high-resolution ultrasound (US) for monitoring vascular compromise after free tissue transfer.

METHODS

Fifty-two tissue transfers in the extremities were included in this study. Blood flow around the anastomotic pedicle and subcutaneous tissue of the grafted flap was monitored with pulsed color and power Doppler US whenever the conventional monitoring method, comprising the bedside assessment of the temperature, capillary refill, and flap color, showed abnormalities until 1 week after reconstruction.

RESULTS

All flaps were indicated for US monitoring, with 44 flaps showing Doppler signals in each position, even though conventional flap monitoring showed an abnormality. Forty of the 44 flaps showed no flap failure, whereas the remaining 4 flaps developed partial necrosis. Abnormal US findings were noted in 8 of the 52 flaps. Ultrasound revealed interruption of venous blood flow around the anastomotic pedicle in 6 of 8 flaps. Emergent exploration revealed venous occlusion at the anastomotic pedicle, similar to the US finding. In 2 of the 8 flaps, US showed no blood flow to either the anastomotic pedicle or subcutaneous tissue. Emergent exploration revealed arterial occlusion at the anastomotic pedicle. Seven of the 8 reexplored flaps were salvaged after revision surgery with complete flap survival. Partial flap survival was noted in 1 case, but complete flap failure was avoided.

CONCLUSIONS

Ultrasound is a useful adjunct that enables a direct assessment of perfusion in grafted tissues, which may reduce unnecessary exploration when conventional flap monitoring shows an abnormality.

Cook-Swartz Doppler Probe Surveillance for Free Flaps-Defining Pros and Cons

Introduction  The main postoperative complication of free flaps is perfusion compromise. Urgent intervention is critical to increase the chances of flap survival. Invasive flap perfusion monitoring with direct blood flow feedback through the Cook–Swartz Doppler probe could enable earlier detection of perfusion complications.

Materials and Methods  Between 2012 and 2016, 35 patients underwent breast reconstruction or defect coverage after trauma with a deep inferior epigastric perforator, anterolateral thigh, transverse musculocutaneous gracilis, gracilis, or latissimus dorsi flap in our department. All flaps were monitored with a Cook–Swartz probe for 10 days postoperatively. The 20 MHz probe was placed around the arterial–venous anastomosis. A flap monitoring protocol was established for standardized surveillance of postoperative perfusion. In the event of probe signal loss, immediate surgical revision was initiated.

Results  Signal loss was detected in 8 of the 35 cases. On return to the operating room, six were found to be true positives (relevant disruption of flap perfusion) and two were false positives (due to Doppler probe displacement). There were also two false negatives, resulting in a slowly progressive partial flap loss. Flap perfusion was restored in three of the six cases (50%) identified by the probe. Following surgical intervention, three of the six cases had persistent problems with perfusion, resulting in two total flap losses and one partial flap necrosis leading to an overall 5.7% total flap loss.

Conclusion  Postoperative flap perfusion surveillance is a complex matter. Surgical experience is often helpful but not always reliable. The costs, false-positive, and false-negative rates associated with invasive perfusion monitoring with Cook–Swartz probe make it most appropriate for buried flaps.

Level of Evidence  This is an original work.

Use of Near-infrared Spectroscopy and Implantable Doppler for Postoperative Monitoring of Free Tissue Transfer for Breast Reconstruction: A Systematic Review and Meta-analysis

BACKGROUND

Failure to accurately assess the perfusion of free tissue transfer (FTT) in the early postoperative period may contribute to failure, which is a source of major patient morbidity and healthcare costs. This systematic review and meta-analysis aim to evaluate and appraise current evidence for the use of near-infrared spectroscopy (NIRS) and/or implantable Doppler (ID) devices compared with conventional clinical assessment (CCA) for postoperative monitoring of FTT in reconstructive breast surgery.

METHODS

A systematic literature search was performed in accordance with the preferred reporting items for systematic reviews guidelines. Studies in human subjects published within the last decade relevant to the review question were identified. Meta-analysis using random-effects models of FTT failure rate and STARD scoring was then performed on the retrieved publications.

RESULTS

Nineteen studies met the inclusions criteria. For NIRS and ID, the mean sensitivity for the detection of FTT failure is 99.36% and 100% respectively, with average specificity of 99.36% and 97.63%, respectively. From studies with sufficient reported data, meta-analysis results demonstrated that both NIRS [OR = 0.09 (0.02-0.36); P < 0.001] and ID [OR = 0.39 (0.27-0.95); P = 0.04] were associated with significant reduction of FTT failure rates compared with CCA.

CONCLUSIONS

The use of ID and NIRS provided equivalent outcomes in detecting FTT failure and were superior to CCA. The ability to acquire continuous objective physiological data regarding tissue perfusion is a perceived advantage of these techniques. Reduced clinical staff workload and minimized hospital costs are also perceived as positive consequences of their use.

Current Techniques for Postoperative Monitoring of Microvascular Free Flaps

Free tissue transfer (FTT) is used in patients with complicated reconstructive needs; it can provide stable wound coverage, improved aesthetic appearance, and restore functional deficits. Despite the high success rates of free flaps, vascular occlusion is a significant risk leading to flap failure. Many studies have demonstrated that the salvage rate for flaps is inversely related to the time between onset of a vascular problem and its surgical correction. As a result, ongoing postoperative monitoring of free flaps for adequate perfusion is imperative to allow timely and accurate diagnosis of vascular compromise. Close monitoring and prompt notification of the physician if vascular compromise occurs are typically undertaken by first-line nurses. We conducted an integrative literature to identify and evaluate commonly used techniques for monitoring vascular free flaps during the postoperative period. We searched PubMed and Science Direct electronic databases, using the key words: "free-flap" and "monitoring." This article discusses commonly monitoring modalities, along with their advantages and limitations. Whereas large academic institutions may have an experienced nursing staff specifically trained in effective methods for monitoring free flap patients, this situation may not exist in all hospitals where free flap surgeries are performed. We describe techniques that allow easy and timely detection of flap compromise by nursing staff while reducing interuser variability.

The unsuitability of implantable Doppler probes for the early detection of renal vascular complications - a porcine model for prevention of renal transplant loss

BACKGROUND

Vascular occlusion is a rare, but serious complication after kidney transplantation often resulting in graft loss. We therefore aimed to develop an experimental porcine model for stepwise reduction of the renal venous blood flow and to compare an implantable Doppler probe and microdialysis for fast detection of vascular occlusion.

METHODS

In 20 pigs, implantable Doppler probes were placed on the renal artery and vein and a microdialysis catheter was placed in the renal cortex. An arterial flowprobe served as gold standard. Following two-hour baseline measurements, the pigs were randomised to stepwise venous occlusion, complete venous occlusion, complete arterial occlusion or controls.

RESULTS

All parameters were stable through baseline measurements. Glutamate and lactate measured by microdialysis increased significantly (p = 0.02 and p = 0.03 respectively) 30 minutes after a 2/3 (66%) reduction in renal blood flow. The implantable Doppler probe was not able to detect flow changes until there was total venous occlusion. Microdialysis detected changes in local metabolism after both arterial and venous occlusion; the implantable Doppler probe could only detect vascular occlusions on the vessel it was placed.

CONCLUSIONS

We developed a new model for stepwise renal venous blood flow occlusion. Furthermore, the first comparison of the implantable Doppler probe and microdialysis for detection of renal vascular occlusions was made. The implantable Doppler probe could only detect flow changes after a complete occlusion, whereas microdialysis detected changes earlier, and could detect both arterial and venous occlusion. Based on these results, the implantable Doppler probe for early detection of vascular occlusions cannot be recommended.

Implantable Doppler monitoring of buried free flaps during vascularized lymph node transfer

BACKGROUND AND OBJECTIVES

Reliable flap monitoring is crucial to the success of free tissue transfer, including vascularized lymph node transfer (VLNT). However, no large-scale study has examined implantable Doppler monitoring in VLNT. We aimed to determine whether an implantable Doppler system can reliably monitor flap perfusion during VLNT and also to calculate the sensitivity and specificity of this system for detecting compromise in the monitored vessel.

METHODS

An analysis of prospectively collected data of patients who underwent buried VLNT with implantable Doppler monitoring between 2014 and 2015 was performed.

RESULTS

A consecutive series of 100 patients underwent VLNT with implantable Doppler monitoring. Five cases required return to the operating room for flap exploration due to a change in Doppler signal quality. All compromised flaps were salvaged. The sensitivity of the implantable Doppler system for flap monitoring was 100%, the specificity was 97.9%, the positive predictive value was 60%, and the negative predictive value was 100%. The false-positive rate was 2%.

CONCLUSIONS

This is the largest reported series of implantable Doppler monitoring of free flap perfusion during VLNT. Our experience suggests that this is a safe and effective technique for postoperative monitoring of VLNT.

A System for Simple Real-Time Anastomotic Failure Detection and Wireless Blood Flow Monitoring in the Lower Limbs

Current totally implantable wireless blood flow monitors are large and cannot operate alongside nearby monitors. To alleviate the problems with the current monitors, we developed a system to monitor blood flow wirelessly, with a simple and easily interpretable real-time output. To the best of our knowledge, the implanted electronics are the smallest in reported literature, which reduces bio-burden. Calibration was performed across realistic physiological flow ranges using a syringe pump. The device’s sensors connected directly to the bilateral femoral veins of swine. For each 1 min, blood flow was monitored, then, an occlusion was introduced, and then, the occlusion was removed to resume flow. Each vein of four pigs was monitored four times, totaling 32 data collections. The implant measured 1.70 cm³ without battery/encapsulation. Across its calibrated range, including equipment tolerances, the relative error is less than ±5% above 8 mL/min and between −0.8% and +1.2% at its largest calibrated flow rate, which to the best of our knowledge is the lowest reported in the literature across the measured calibration range. The average standard deviation of the flow waveform amplitude was three times greater than that of no-flow. Establishing the relative amplitude for the flow and no-flow waveforms was found necessary, particularly for noise modulated Doppler signals. Its size and accuracy, compared with other microcontroller-equipped totally implantable monitors, make it a good candidate for future tether-free free flap monitoring studies.

Do adjunctive flap-monitoring technologies impact clinical decision making? An analysis of microsurgeon preferences and behavior by body region

BACKGROUND

Multiple perfusion assessment technologies exist to identify compromised microvascular free flaps. The effectiveness, operability, and cost of each technology vary. The authors investigated surgeon preference and clinical behavior with several perfusion assessment technologies.

METHODS

A questionnaire was sent to members of the American Society for Reconstructive Microsurgery concerning perceptions and frequency of use of several technologies in varied clinical situations. Demographic information was also collected. Adjusted odds ratios were calculated using multinomial logistic regression accounting for clustering of similar practices within institutions/regions.

RESULTS

The questionnaire was completed by 157 of 389 participants (40.4 percent response rate). Handheld Doppler was the most commonly preferred free flap-monitoring technology (56.1 percent), followed by implantable Doppler (22.9 percent) and cutaneous tissue oximetry (16.6 percent). Surgeons were significantly more likely to opt for immediate take-back to the operating room when presented with a concerning tissue oximetry readout compared with a concerning handheld Doppler signal (OR, 2.82; p < 0.01), whereas other technologies did not significantly alter postoperative management more than simple handheld Doppler. Clinical decision making did not significantly differ by demographics, training, or practice setup.

CONCLUSIONS

Although most surgeons still prefer to use standard handheld Doppler for free flap assessment, respondents were significantly more likely to opt for immediate return to the operating room for a concerning tissue oximetry reading than an abnormal Doppler signal. This suggests that tissue oximetry may have the greatest impact on clinical decision making in the postoperative period.

The venous anatomy of the abdominal wall for Deep Inferior Epigastric Artery (DIEP) flaps in breast reconstruction

BACKGROUND

Despite improving outcomes, venous problems in the harvest of deep inferior epigastric artery perforator (DIEP) flaps remain the more common vascular complications. However, it is apparent that the venous anatomy of the anterior abdominal wall has not been described to the same extent as the arterial anatomy. Cadaveric dissection studies of venous anatomy frequently lack the detail of their arterial counterparts. Venous valves complicate retrograde injection, resulting in poor quality studies with limited anatomical information.

METHODS

The current manuscript comprises a review of the literature, highlighting key features of the anatomy of the venous drainage of the abdominal wall integument, with particular pertinence to DIEP flaps. Both cadaveric and clinical studies are included in this review. Our own cadaveric and in-vivo studies were undertaken and included in detail in this manuscript, with the cadaveric component utilizing direct catheter venography and the in-vivo studies were undertaken using preoperative computed tomographic angiography (CTA), mapping in-vivo venous flow.

RESULTS

Several key features of the venous anatomy of the abdominal wall render it different to other regions, and are of particular importance to DIEP flap transfer.

CONCLUSIONS

The cause of venous compromise is multi-factorial, with perforator diameter, midline crossover, and deep-superficial venous communications all important. Venous cadaveric studies as well as clinical CTA preoperatively can identify these anomalies.

The efficacy of the Cook-Swartz implantable Doppler in the detection of free-flap compromise: a systematic review protocol

INTRODUCTION

The Cook-Swartz implantable Doppler monitors venous or arterial blood flow from free flaps and can detect free-flap compromise. Previous studies have shown that the use of this Doppler can improve detection and salvage rates as it provides an earlier warning than the current method of clinical assessment. Such studies assert that the implantable Doppler is of great value in monitoring free flaps in current microsurgical units. This systematic review aims to compare the efficacy of the Cook-Swartz implantable Doppler in monitoring free-flap compromise against conventional clinical free-flap monitoring techniques.

METHODS AND ANALYSIS

Various electronic databases will be systematically searched for studies that compare the use of Cook-Swartz implantable Doppler with clinical assessment. The selected studies will then have their titles and abstracts screened by two authors. Articles selected after title and abstract screen will have full text downloaded and the complete article will be assessed for suitability. Once the articles have been selected for inclusion, data extraction will take place. For data analysis, the outcomes of the studies will be tabulated, with descriptive statistics performed as appropriate and the detection rate of the Doppler and clinical assessment will be compared and synthesised where possible.

ETHICS AND DISSEMINATION

The authors hope to disseminate the findings as widely as possible. This systematic review will be published in a peer-reviewed journal and include a number of recommendations as its conclusion based on the evidence contained within. Given the wide range of specialties now utilising flaps, it will be presented at a wide range of national and international conferences.

PROTOCOL REGISTRATION IN PROSPERO

CRD42013005818 The literature search and data extraction went on until 28 January 2014. These steps were revised in line with peer review comments.

The effect of learning curve on flap selection, re-exploration, and salvage rates in free flaps; A retrospective analysis of 155 cases

The purpose of this study is to report our experience and learning curve in avoiding complications at both the recipient and donor sites as well in choosing the best flap for different anatomic locations. For this purpose 155 free flaps done between October 2005 and August 2012 were retrospectively examined. Patient demographics, flap types, etiology, re-exploration indications, timing of the re-explorations, and salvage rates were documented. In the first 60 cases, our re-exploration rate was 26.7% (16 flaps), and the rate decreased to 15.0% for the second 60 flaps (9 flaps). In correlation with this decrease, in the last 35 cases, only three flaps were re-explored (8.6%). This decrease in re-exploration rates over time was statistically significant (P = 0.021). Re-exploration rates for axial and perforator flaps were 14.6% and 22.7%, respectively. Salvage rates were 76.9% in axial flaps and 53.3% in perforator flaps. The total success rate for axial flaps was 95.5% and for perforator flaps was 89.4%. Besides, re-exploration rates were higher with lower salvage rates in perforator flaps compared to axial flaps causing lower overall success rates in the former group. The mean time of re-explorations was 21.4 hours. Salvage rates were significantly higher in re-explorations done within the first 12 hours after the initial surgery than in re-explorations done after 12 hours (83.3% vs. 47.3%) (P = 0.040). We can conclude that axial flaps have a steeper learning curve and are safer options for the inexperienced reconstructive micro-surgeons until they have adequate experience with the perforator dissection.

Implantable Doppler in monitoring free flaps: a cost-effectiveness analysis based on a systematic review of the literature

OBJECTIVE

The purpose of this paper is to evaluate the efficacy and cost-effectiveness of the implantable Doppler system based on the analysis of the available scientific literature and clinical and cost data available in our hospital. The results of this system are compared to those of conventional free flap monitoring methods.

MATERIALS AND METHODS

The literature published between 1991 and 2011 was systematically reviewed. All available cost data were collected and several simulations were performed. A retrospective assessment of the efficacy of conventional methods in our hospital was also conducted.

RESULTS AND CONCLUSION

The implantable Doppler system is more effective than the conventional methods used to monitor free flap perfusion. The mean flap salvage rate with the implantable Doppler was 21 percentage points higher (81.4 vs. 60.4). The excess cost compared to conventional methods was about CAD 120 per patient (about EUR 94). However, this excess cost can be compensated or even reversed, depending on the initial flap salvage rate in the health facility and the type of free flap (buried vs. non-buried).

Eight-year experience of the Cook-Swartz Doppler in free-flap operations: microsurgical and reexploration results with regard to a wide spectrum of surgeries

BACKGROUND

Microvascular free flap has become an increasingly popular useful method of reconstruction over the past few decades. Minimizing failure rates in these operations is a primary goal in every microsurgical unit that can be accomplished by early recognition.

METHODS

In this retrospective study, we tracked the admission of the implantable Doppler in the microsurgical unit (2000-2007) and evaluated parameters measured from 473 consecutive patients who underwent a total of 548 microsurgical procedures (489 primary surgeries and 59 reexplorations). The effectiveness of the Cook-Swartz Doppler (Cook Medical®) was examined in juxtapose general and subspecialty's aspects: in each microsurgical subspecialty, we compared the overall success and failure rates of the group with the implantable Doppler (n = 259) with the control group monitored by clinical means (n = 289). We also examined the duration, outcomes, and the effectiveness of this device in reexploration operations.

RESULTS

Overall, success rates were improved by using the implantable Doppler contrary to clinical assessment (96.14% vs. 89.27%) with a statistical significant (P < 0.005). The device was most effective in ENT (94.6% vs. 84%), breast reconstructive surgeries (97.3% vs. 82.36%), and orthopedic oncology (97.37% vs. 83.72%), whereas with reanimation operations and trauma/orthopedics subspecialties, it showed no necessity. In neurosurgery and in other/esthetic surgeries, the study was too small to draw definite deductions.

CONCLUSIONS

We recommend the usage of the implantable Doppler probe as an effective monitoring system for free-flap surgeries, with emphasis on subspecialties where the device demonstrated better results than traditional monitoring methods.

Postoperative monitoring of lower limb free flaps with the Cook-Swartz implantable Doppler probe: A clinical trial

BACKGROUND

Free flaps to the lower limb have inherently high venous pressures, potentially impairing flap viability, which may lead to limb amputation if flap failure ensues. Adequate monitoring of flap perfusion is thus essential, with timely detection of flap compromise able to potentiate flap salvage. While clinical monitoring has been popularized, recent use of the implantable Doppler probe has been used with success in other free flap settings.

METHODS

A comparative study of 40 consecutive patients undergoing microvascular free flap reconstruction of lower limb defects was undertaken, with postoperative monitoring achieved with either clinical monitoring alone or the use of the Cook-Swartz implantable Doppler probe.

RESULTS

The use of the implantable Doppler probe was associated with salvage of 2/2 compromised flaps compared to salvage of 2/5 compromised flaps in the group undergoing clinical monitoring alone (salvage rate 100% vs. 40%, P = 0.28). While not statistically significant, this was a strong trend toward an improved flap salvage rate with the use of the implantable Doppler probe. There were no false positives or negatives in either group. One flap loss in the clinically monitored group resulted in limb amputation (the only amputation in the cohort).

CONCLUSION

A trend toward early detection and salvage of flaps with anastomotic insufficiency was seen with the use of the Cook-Swartz implantable Doppler probe. These findings suggest a possible benefit of this technique as a stand-alone or adjunctive tool in the clinical monitoring of free flaps, with further investigation warranted into the broader application of these devices.

The efficacy of postoperative monitoring: a single surgeon comparison of clinical monitoring and the implantable Doppler probe in 547 consecutive free flaps

BACKGROUND

An important element in achieving high success rates with free flap surgery has been the use of different techniques for monitoring flaps postoperatively as a means to detecting vascular compromise. Successful monitoring of the vascular pedicle to a flap can potentiate rapid return to theater in the setting of compromise, with the potential to salvage the flap. There is little evidence that any technique offers any advantage over clinical monitoring alone.

METHODS

A consecutive series of 547 patients from a single plastic surgical unit who underwent a fasciocutaneous free flap operation for breast reconstruction [deep inferior epigastric artery perforator (DIEP) flap, superficial inferior epigastric artery (SIEA) flap, or superior gluteal artery perforator (SGAP) flap] were included. A comparison was made between the first 426 consecutive patients in whom flap monitoring was performed using clinical monitoring alone and the subsequent 121 patients in whom monitoring was achieved with the Cook-Swartz implantable Doppler probe. Outcome measures included flap salvage rate and false-positive rate.

RESULTS

There was a strong trend toward improved salvage rates with the implantable Doppler probe compared with clinical monitoring (80% vs. 66%, P = 0.48). When combined with the literature (meta-analysis), the data prove statistically significant (P < 0.01). There was no statistical difference between the groups for false-positive rates.

CONCLUSION

Flap monitoring with the implantable Doppler probe can improve flap salvage rates without increasing the rate of false-positive takebacks.