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

Implantable arterial doppler efficacy in free flap reconstruction: A systematic review and meta-analysis

The implantable arterial doppler (IAD) is frequently used to postoperatively monitor free flaps with high accuracy, but there are no guidelines for its use. Bedside exam is used adjunctively to determine necessary intervention. This systematic review seeks to discover why the doppler is used adjunctively despite its established record of accuracy. Criteria for inclusion and exclusion were established. In total, 280 articles were found on PubMed and Web of Science, then screened accordingly. Data from 22 articles were analyzed using a bivariate hierarchical random effects model. Twenty-two studies yielded 2996 total patients undergoing 3127 free flap procedures. The meta-analysis found a high sensitivity of 0.809 (95% CI = 0.709, 0.880) and specificity of 0.966 (95% CI = 0.947, 0.979). False-positive rate was found to be 0.034 (95% CI = 0.021, 0.053). Positive and negative predictive values were 0.711 (95% CI = 0.581, 0.817) and 0.979 (95% CI = 0.966, 0.988). Positive and negative likelihood ratios were 24.7 (95% CI = 14.5, 39.5) and 0.20 (95% CI = 0.12, 0.30). The established efficacy of the IAD is supported by this study. Clinical exams may remain as the final adjunct due to the risks of inaccurate IAD signals. Further studies are warranted to optimize its use for future practice guidelines.

Outcomes for Physiologic Microsurgical Treatment of Secondary Lymphedema Involving the Extremity

OBJECTIVE

The aim of this study was to examine the long-term impact of physiologic surgical options, including VLNT and LVB, on patients with secondary lymphedema of the upper or lower extremity (UEL/LEL).

SUMMARY BACKGROUND DATA

VLNT and LVB have become increasingly popular in the treatment of lymphedema. However, there is a paucity of long-term data on patient outcomes after use of these techniques to treat lymphedema.

METHODS

An analysis of prospectively collected data on all patients who underwent physiologic surgical treatment of secondary lymphedema over a 5.5-year period was performed. Patient demographics, surgical details, subjective reported improvements, LLIS scores, and postoperative limb volume calculations were analyzed.

RESULTS

Two hundred seventy-four patients with secondary lymphedema (197 upper, 77 lower) were included in the study. More than 87% of UEL patients and 60% of LEL patients had reduction in excess limb volume postoperatively. At 3 months postoperatively, patients with UEL had a 31.1% reduction in volume difference between limbs, 33.9% at 6 months, 25.7% at 12 months, 47.4% at 24 months and 47.7% at 4 years. The reduction in limb volume difference followed a similar pattern but was overall lower for LEL patients. Greater than 86% of UEL and 75% of LEL patients also had improvement in LLIS scores postoperatively. Fifty-nine complications occurred (12.9%); flap survival was >99%.

CONCLUSIONS

Patients with secondary UEL/LEL who undergo VLNT/LVB demonstrate improved functional status and reduced affected limb volumes postoperatively. Patients with UEL seem to have a more substantial reduction in limb volume differential compared to LEL patients.

Preliminary outcomes of combined surgical approach for lower extremity lymphedema: supraclavicular lymph node transfer and lymphaticovenular anastomosis

BACKGROUND

Vascularized lymph node transfer (VLNT) is a well-established surgical approach for treating lower extremity lymphedema (LEL). Since VLNT takes time to show effect, a combined approach with lymphaticovenular anastomosis (LVA) may be more advantageous to patients by inducing an immediate improvement. This study aims to describe our experience and evaluate the results of a combined approach.

METHODS

In this retrospective review, we analyzed a total of 12 patients that underwent simultaneous supraclavicular VLNT and LVA for the treatment of secondary LEL with the ISL stage II or III. Patients who had a follow-up period of less than 12 months were excluded. The supraclavicular flap, including superficial lymphoid tissue as well as deep cervical nodes, was harvested and anastomosed to the posterior tibial vessels. The pre- and postoperative change of circumference difference ratios and LEL index were compared.

RESULTS

All twelve flaps survived without re-exploration. An average of 2.3 LVAs were simultaneously performed. At 12.9 months of follow-up (range, 12-16 months), the postoperative mean circumference ratio was significantly improved than pre-operative in 10 cm above the knee (7.9 ± 7.2% vs 15.0 ± 7.6%, p = 0.01), 10 cm below the knee (8.5 ± 7.5% vs 17.4 ± 12.7%, p = 0.03) and lateral malleolus (16.5 ± 15.5% vs 28.6 ± 17.9%, p = 0.03). Also, the mean LEL index was decreased (preoperative 324.3 ± 53.0 vs postoperative 298.0 ± 44.6, p = 0.242) and eight patients showed improvement in LEL stage.

CONCLUSIONS

The combined approach showed a significant decrease in the circumference of LEL. Additional LVAs could reinforce the effect of a VLNT. Larger series with longer follow-up is needed to confirm our findings.

Intraoperative Utility of the Implantable Doppler in Lower Extremity Reconstruction: A Matched Case-control Study

Background:

Patients with diabetes mellitus and peripheral vascular disease have high rates of thrombogenic vessels. The implantable (Cook) Doppler in lower extremity reconstruction can optimize microsurgical outcomes in this population.

Methods:

Patients undergoing lower extremity free flap reconstruction who did not have an implantable Doppler probe placed were matched with patients who received an implantable Doppler probe. Groups were matched based on wound location, history of peripheral vascular disease, number of vessel runoffs, and number of venous anastomoses and postoperative outcomes compared.

Results:

Thirty patients were included: 15 in the control group and 15 in the implantable Doppler group. Mean age was 60.2 ±10.2 years, and mean BMI was 28.7 ± 5.0 kg/m². There was a high prevalence of diabetes mellitus (13; 43.3%) and peripheral vascular disease (4; 13.3%). Takebacks due to vascular compromise were significantly higher in the control than in the implantable Doppler group (26.7% versus 0.0%, P = 0.032). Among flaps that required takeback to the operating room, the majority were muscle-based without a skin paddle (75.0%). Vascular compromise was due to arterial insufficiency in 2 cases and venous thrombosis in 1 case. The salvage rate among the takebacks of the non-implantable Doppler group was 0.0%, resulting in a 26.7% flap failure rate in the non-implantable Doppler group when compared with 0.0% flap loss in the implantable Doppler group (P = 0.032).

Conclusion:

The implantable Doppler probe optimizes flap inset intraoperatively in lower extremity free flap reconstruction and can significantly decrease takebacks due to vascular complications, thereby increasing flap success.

Adverse Events Associated with Implantable Dopplers during Microvascular Surgery

BACKGROUND

 Implantable Dopplers (IDs) are widely used for postoperative free flap vascular monitoring. However, IDs may contribute to free flap complications or failure and better understanding of device malfunctions is needed.

METHODS

 The U.S. Food and Drug Administration's Manufacturer and User Facility Device Experience database was queried for all reports of ID adverse events from two leading manufacturers (Cook Vascular and Synovis Life Technologies) in free flap surgery from January 2010 to March 2020. Reports were reviewed and categorized. A comparison of reoperations within select categories was performed using Chi-square analysis.

RESULTS

 Of 209 included reports, the most common device malfunctions were venous anastomotic coupler misalignment (35.4%) and coupler ring detachment (24.4%). Synovis devices were used in 100% of reports of vessel compression and Cook Vascular devices were used in 77.7% of reports of probe detachment. Of 74 patient-related adverse events, the most common were reoperation (47.3%) and vessel occlusion (28.4%). Of five reported events of flap failure, two were associated with loss of ID signal. The proportion of Doppler signal loss events leading to reoperation was significantly greater than the proportion of any other Doppler-related event leading to reoperation. Intraoperative coupler replacement was the most commonly reported intervention (n = 86), and venous anastomosis with hand-suturing occurred in 30 device malfunctions.

CONCLUSION

 This study demonstrates a variety of ID-related malfunctions. One-third of device malfunctions were associated with patient complications, and false-positive Doppler signal loss contributed substantially to the requirement of surgical re-exploration. These are important considerations for surgical teams utilizing IDs in free tissue transfer procedures.

A comparative analysis using flowmeter, laser-Doppler |spectrophotometry, and indocyanine green-videoangiography for detection of vascular stenosis in free flaps

The effects of gradual vascular occlusion on the blood supply of perfused areas are poorly described. Information relating to the comparison of flap monitoring techniques is lacking. Varying stenotic conditions (0%, 25%, 50%, 75% and 100%) were generated on purpose at the A. and V. femoralis in the rat model. Analyses included flowmeter, simultaneous laser-Doppler flowmetry and tissue spectrophotometry (O2C) and indocyanine green- (ICG-) videoangiography with integrated FLOW 800 tool. A Random Forests prediction model was used to analyse the importance of each method to diagnose the stenotic conditions. The ability to discriminate and to accurately estimate the probability of stenosis was assessed by Receiver Operating Characteristic (ROC) curves and calibration plots. Blood flow changes for all modalities were described in detail. Flowmeter displayed earliest a linear decrease as a result of increasing stenosis. A stenosis of 50% degrees was most difficult to detect correctly. The combination of flowmeter and ICG-videoangiography showed high diagnostic power for each stenotic situation (area under the ROC > 0.79). Flowmeter and ICG-videoangiography showed to be most relevant in detection of varying stenotic conditions and may change the clinical outcome. The O2C showed less effect on varying stenotic situations as the only surface monitoring device.

Management of High-Output Chyle Leak after Harvesting of Vascularized Supraclavicular Lymph Nodes

Vascularized lymph node transfer is a physiologic microsurgical technique used for the treatment of lymphedema. As vascularized lymph node transfer is becoming more common, it is essential that one is aware of all potential complications associated with vascularized lymph node transfer and know how to avoid and manage them when they do occur. The authors recently encountered a complication after supraclavicular vascularized lymph node transfer that has not been previously reported. A patient developed a recalcitrant high-output (>500 ml/day) chyle leak in the neck donor site after supraclavicular vascularized lymph node transfer harvest. In this article, the authors share their experience with massive chyle leak and review the management strategies of how to effectively avoid and treat this potentially dangerous complication. This review of a previously unreported complication of supraclavicular vascularized lymph node transfer is timely and important, as this procedure is increasingly being offered to patients, and surgeons performing these procedures should be familiar with effectively managing this potentially dangerous complication. CLINICAL QUESTION/LEVEL OF EVIDENCE:: Therapeutic, V.