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Introduction With increasing popularity of minimally invasive approaches to abdominoperineal resection (APR), thigh-based flaps are becoming the preferred option for reconstruction. The gluteal-thigh flap provides sufficient bulk, albeit with a high complication rate. We reevaluated the vascularization and design of the gluteal-thigh flap. The purpose of this study is to highlight the importance of the vascularization of the posterior thigh skin by the descending branch of the inferior gluteal artery (IGA) and the profunda femoris artery (PFA) perforators to design a more reliable and versatile gluteal thigh flap. This flap is indicated in selected cases in which use of vertical rectus abdominis musculocutaneous flap is not feasible. Methods Eleven fresh cadavers were used. The course, distribution, and diameter of IGA and PFA perforators were recorded. A wide posterior gluteal-thigh propeller flap (WPGTPF) was designed including the distance between the ischiatic tuberosity and greater trochanter; and extending it to within 8 cm of the popliteal fossa to improve flap reliability. Ten patients (mean age of 58.7 ± 10.6 years) underwent APR due to anal cancer (2) and rectal cancer (8); the approach was open in 3, laparoscopic in 6, and robotic in 1. All 10 patients received unilateral flap with a width of 12 ± 3.3 cm and surface of 405.5 ± 175.9 cm2 . Results The descending branch of the IGA was dominant in 72.7% of the specimens. In 22.7% of the specimens, the pedicle of the flap derived from the first or second PFA perforators. In one case, there was a double vascularization. Descending branch of the IGA was mapped at 46 ± 7.96 mm on the X-axis (horizontal line from the ischial tuberosity [IT] to the greater trochanter) and -12.1 ± 17.9 mm on the Y-axis (vertical line from the IT to the Medial Femoral condyle). Its average caliber measured 2.18 ± 0.3 mm. The first and second PFA perforators were located at 101.6 ± 17.9 mm and 104.5 ± 15.5 mm on the X-axis; 35.9 ± 27.1 mm and 89.2 ± 37.6 mm on the Y-axis. Their average diameters were 1.84 ± 0.41 mm and 1.48 ± 0.3 mm. In two cases, the flap was based on the first PFA perforator, the rest were on the descending branch of the IGA. Neither complete nor partial flap necrosis was observed. One patient developed coccyx osteomyelitis treated and resolved with bone debridement and one patient developed a seroma of the lateral thigh that was treated conservatively. Three patients underwent a debulking procedure by a combination of liposuction and resection to improve the gluteal symmetry. All ten flaps survived completely. Conclusions Harvest of a wide flap that includes the PFA perforators and implementation of the propeller design increase the survival and versatility of the flap.

Introduction Ex-vivo normothermic limb perfusion (EVNLP) has been proven to preserve limb viability better than standard cold storage. Perfusates containing packed red blood cells (pRBC) improve outcomes when compared to acellular perfusates. Limitations of pRBC-based perfusion include limited availability, need for cross match, mechanical hemolysis, and activation of pro-inflammatory proteins. Hemoglobin-based oxygen carrier (HBOC)-201 (Hemopure) is a solution of polymerized bovine hemoglobin, characterized by low immunogenicity, no risk of hemolytic reaction, and enhanced convective and diffusive oxygen delivery. This is a preliminary study on the feasibility of EVNLP using HBOC-201 as an oxygen carrier. Materials and Methods Three porcine forelimb perfusions were performed using an established EVNLP model and an HBOC-201-based perfusate. The perfusion circuit included a roller pump, oxygenator, heat exchanger, and reservoir. Electrolytes, limb temperature, weight, compartment pressure, nerve conduction, and perfusion indicated by indocyanine green angiography and infra-red thermography were monitored. Histological evaluation was performed with hematoxylin and eosin and electron microscopy. Results Three limbs were perfused for 21.3 ± 2.1 hours. Muscle contractility was preserved for 10.6 ± 2.4 hours. Better preservation of the mitochondrial ultrastructure was evident at 12 hours in contrast to crystallization and destruction features in the cold-storage controls. Conclusions An HBOC-201-EVNLP produced outcomes similar to RBC-EVNLP with preservation of muscle contractility and mitochondrial structure.

Ex vivo normothermic limb perfusion (EVNLP) preserves amputated limbs under near-physiologic conditions. Perfusates containing red blood cells (RBCs) have shown to improve outcomes during ex vivo normothermic organ perfusion, when compared with acellular perfusates. To avoid limitations associated with the use of blood-based products, we evaluated the feasibility of EVNLP using a polymerized hemoglobin-based oxygen carrier-201 (HBOC-201).Twenty-four porcine forelimbs were procured from Yorkshire pigs. Six forelimbs underwent EVNLP with an HBOC-201-based perfusate, six with an RBC-based perfusate, and 12 served as static cold storage (SCS) controls. Ex vivo normothermic limb perfusion was terminated in the presence of systolic arterial pressure of 115 mm Hg or greater, fullness of compartments, or drop of tissue oxygen saturation by 20%. Limb contractility, weight change, compartment pressure, tissue oxygen saturation, oxygen uptake rates (OURs) were assessed. Perfusate fluid-dynamics, gases, electrolytes, metabolites, methemoglobin, creatine kinase, and myoglobin concentration were measured. Uniformity of skin perfusion was assessed with indocyanine green angiography and infrared thermography.Warm ischemia time before EVNLP was 35.50 ± 8.62 minutes (HBOC-201), 30.17 ± 8.03 minutes (RBC) and 37.82 ± 10.45 (SCS) (p = 0.09). Ex vivo normothermic limb perfusion duration was 22.5 ± 1.7 hours (HBOC-201) and 28.2 ± 7.3 hours (RBC) (p = 0.04). Vascular flow (325 ± 25 mL·min-1 vs. 444.7 ± 50.6 mL·min-1; p = 0.39), OUR (2.0 ± 1.45 mL O2·min-1·g-1 vs. 1.3 ± 0.92 mL O2·min-1·g-1 of tissue; p = 0.80), lactate (14.66 ± 4.26 mmol·L-1 vs. 13.11 ± 6.68 mmol·L-1; p = 0.32), perfusate pH (7.53 ± 0.25 HBOC-201; 7.50 ± 0.23 RBC; p = 0.82), flexor (28.3 ± 22.0 vs. 27.5 ± 10.6; p = 0.99), and extensor (31.5 ± 22.9 vs. 28.8 ± 14.5; p = 0.82) compartment pressures, and weight changes (23.1 ± 3.0% vs. 13.2 ± 22.7; p = 0.07) were not significantly different between HBOC-201 and RBC groups, respectively. In HBOC-201 perfused limbs, methemoglobin levels increased, reaching 47.8 ± 12.1% at endpoint. Methemoglobin saturation did not affect OUR (ρ = -0.15, r2 = 0.022; p = 0.45). A significantly greater number of necrotic myocytes was found in the SCS group at endpoint (SCS, 127 ± 17 cells; HBOC-201, 72 ± 30 cells; RBC-based, 56 ± 40 cells; vs. p = 0.003).HBOC-201- and RBC-based perfusates similarly support isolated limb physiology, metabolism, and function.

Background: Ex-vivo normothermic perfusion (EVNP) has been used as an alternative to static cold storage (SCS) to improve allograft quality in solid organ and vascularized composite allotransplantation (VCA). Perfusates containing red blood cells (RBCs) have shown to improve outcomes during ex vivo normothermic organ perfusion when compared to acellular perfusates. However, the use of blood products is challenging due to limited availability, the need for cross-matching, and potential blood-borne infection transmission. To avoid limitations associated with the use of blood-based products, we evaluated the feasibility of EVNLP utilizing a polymerized Hemoglobin-Based Oxygen Carrier-201 (HBOC-201). Methods: Twenty-four porcine forelimbs were procured from Yorkshire pigs following euthanasia. Six forelimbs underwent EVNLP with an HBOC-201 based perfusate, six with an RBC-based perfusate, and twelve served as static cold storage (SCS) controls. EVNLP termination criteria included systolic arterial pressure ≥115 mmHg, fullness of compartments, or tissue oxygen saturation drop by 20%. Limb contractility, weight change, compartment pressure, tissue oxygen saturation, oxygen uptake rates (OUR) were assessed. Perfusate fluid-dynamics, gases, electrolytes, metabolites, methemoglobin (MetHb), creatine kinase (CK), and myoglobin concentration were measured. Limb viability was assessed with indocyanine green (ICG) angiography, infrared thermography (IRT), and muscle histology. Results: Warm ischemia time before EVNLP was 35.50±8.62 min in HBOC-201 perfused limbs and 30.17±8.03 min in RBC-perfused limbs (p=0.07). EVNLP duration in HBOC-201 and RBC-perfused limbs was 22.5±1.7 and 28.2±7.3 hours, respectively (p=0.04). Vascular flow (325±25 vs. 444.7±50.6 ml/min; p=0.39), OUR (2.0±1.45 vs. 1.3±0.92 mlO2/min*g of tissue; p=0.80), lactate (14.66±4.26 vs. 13.11±6.68 mmol/L; p=0.32), and perfusate pH (7.53±0.25 HBOC-201; 7.50±0.23 RBC; p=0.82) were not significantly different between treatment groups. Additionally, flexor (28.3±22.0 vs. 27.5±10.6; p=0.99) and extensor (31.5±22.9 vs. 28.8±14.5; p=0.82) compartment pressures, contractility (3±2 vs. 4±1 p=0.57), and percent weight change (23.1±3.0% vs. 13.2±22.7%; p=0.07) were not significantly different between HBOC-201 and RBC groups. In HBOC-201 perfused limbs, MetHb levels increased, reaching 47.8±12.1% at endpoint. Methemoglobin saturation did not affect OUR (ρ = -0.15, r2 = 0.022; p=0.45). Distal tissue preservation was confirmed by IRT and ICG angiography in both EVNLP groups. Hypoxic cell clusters were identified in the SCS control group at endpoint and were absent in both treatment arms. Conclusion: HBOC-201- and RBC-based perfusates similarly support isolated limb physiology, metabolism, and function. Optimization of modifiable factors, including HBOC-201 oxidation, may extend EVNLP durations employing HBOC-201 and overcome logistical constraints of the utilization of traditional blood products.

In this review, we aim to introduce the concept of machine perfusion of vascularized composite allografts (VCAs). We briefly discuss the basic elements of the circuit design, role of the temperature during the perfusion, types of perfusate, and future trends in this field. Several large animal models have demonstrated the efficacy of machine perfusion over static cold storage. While the maximum allowable ischemia time in VCA is 4–6 h with cold storage method, promising results have been achieved in extended preservation times up to 24 h in machine perfusion technique. Current evidence shows that machine perfusion of VCA can overcome the limitations of static cold storage technique and not only can be considered as a preservation but also as a diagnostic and therapeutic method for the practice of replantation/transplantation.

Background Fat transfer is the most popular means of gluteal augmentation. However, this procedure may be complicated by pulmonary fat embolisms (PFEs). Of 135 PFEs out of 198,857 cases reported by the Aesthetic Surgery Education and Research Foundation task force, 32 were fatal, contributing to the mortality risk of this procedure being as high as 1:2351. Objectives The aim of this study was to generate an anatomic map of the 3-dimensional location and variability in size of the gluteal region vessels. Methods Twenty cadaveric gluteal regions were dissected. The aorta, venae cavae, popliteal, and saphenous veins were cannulated and injected with colored latex. Dissection was performed subcutaneously, in the gluteus maximus (GM), and submuscularly to evaluate the number and vascular distribution of all the vessels. Vessels were mapped on an XYZ axis. Results The subcutaneous plane, containing 25 vessels on average, had the smallest vessel diameters (artery, 0.9 [0.3] mm; vein, 1.05 [0.22] mm). The GM vein diameter was 1.3 [0.3] mm. Branches of the inferior gluteal vessels had arterial and venous calibers of 2.2 [0.04] mm and 3.5 [0.99] mm, respectively. Superior gluteal artery and vein branches were 1.8 [0.2] mm and 3.85 [1.9] mm in diameter, respectively. Superior and inferior gluteal vein diameters were 7.61 [2.24] mm and 13.65 [6.55] mm, respectively. Conclusions The deeper and more medial planes of the gluteal region house larger, more prominent vessels. This research objectifies and is consistent with recommendations made by various recent task force reports to limit fat transfer to the subcutaneous plane.

Histomorphometry quantitatively evaluates nerve regeneration. Total myelinated fiber count (TMFC) is most accurately obtained manually across full nerve cross-sections, but most researchers opt for automated, sampled analysis. Few of the numerous techniques available have been validated. The goal of this study was to compare common histomorphometric methods (full manual [FM], sampled manual [SM], and sampled automatic [SA]) to determine their reliability and consistency.Twenty-four rats underwent sciatic nerve (SN) repair with 20mm isografts; SNs distal to the graft were analyzed. TMFC was manually determined in each full cross-section. Counts were also extrapolated from sampled fields, both manually and automatically with ImageJ software. Myelinated fiber diameter, axon diameter, and myelin sheath thickness were measured manually in full and sampled fields; G-ratio was calculated. Repeated-measures MANOVA, Spearman correlation, and Wilcoxon signed-rank tests were performed. A systematic review of histomorphometry in rat SN repair was performed to analyze the variability of techniques in the literature.FM TMFC was 13,506 ± 4,217. Both sampled methods yielded significantly different TMFCs (SM:14.4 ± 13.4%, P0.001; SA:21.8 ± 44.7%, P = 0.037). All three methods strongly correlated with each other, especially FM and SM (rSM and SA analysis are reliable with standardized, systematic sampling. Transparency is essential to allow comparison of data; meanwhile, researchers must be cognizant of the wide variety of methodologies in the literature.

Background The anterior or submental necklift has been well described. Long-term results have been demonstrated in patients with minimal, mild, and moderate skin excess. It relies on the skin’s unique ability to contract once separated from its attachments and further enhances the surgical result with treatment of the intermediate layer- subplatysmal fat, anterior digastric, submandibular gland, and platysma. Treatment of this layer differentiates this operation from liposuction and offers benefits beyond liposuction alone. Objectives The authors sought to assess the long-term success of the anterior necklift for neck rejuvenation and determine its utility in patients with severe cervicomental angles. Methods This was a single-surgeon, retrospective review of patients who underwent an isolated anterior necklift with no additional procedures between 1998 and 2017. Pre- and postprocedure photographs were scrambled and examined by independent evaluators grading the change in cervicomental angle based on the Knize scale. The reduction in apparent age was calculated utilizing the validated apparent age assessment scale. Results Twenty-seven patients were evaluated (42% mild and 58% moderate to severe necks preoperatively). The average follow-up was 24.7 months. There was an average 3.6-year age reduction and 1.0-grade improvement in all patients. In moderate to severe necks, there was a 3.9-year age reduction and 1.4-grade improvement in the cervicomental angle following surgery. Conclusions This study demonstrates the effectiveness of the operation in improving the cervicomental angle and reducing the overall apparent age of patients, even more so in severe cases. The operation is an option for patients who desire neck improvement but are unwilling to undergo a facelift. Level of Evidence: 4

Background: Leukodepletion of whole blood-based perfusates remains a challenge in experimental models of ex vivo perfusion. This study investigated the leukoreduction efficacy of the commonly used LeukoGuard LG Arterial and BC2 Cardioplegia filters. Methods: Eleven liters of washed porcine blood was used to evaluate the filtration efficiency of LG (n = 6) and BC2 (n = 5) filters. Filter efficacy was tested by passing 1 L of washed blood through each filter. Complete blood count was performed to detect a reduction of white blood cells, red blood cells, and hemoglobin concentration. Results: The BC2 Cardioplegia filter showed a significant reduction in white blood cell count (13.16 ± 4.2 × 103 cells/μL pre-filtration, 0.62 ± 0.61 cells/μL post-filtration, p = 0.005), red blood cell count (9.18 ± 0.16 × 106 cells/μL pre-filtration, 9.02 ± 0.16 × 106 cells/μL post-filtration, p = 0.012) and hemoglobin concentration (15.89 ± 0.66 g/dL pre-filtration, 15.67 ± 0.83 g/dL post-filtration, p = 0.017). Platelet reduction in the LG filter group was statistically significant (13.23 ± 13.98 × 103 cells/μL pre-filtration, 7.15 ± 3.31 × 103 cells/μL post-filtration, p = 0.029), but no difference was seen in the BC2 group. There was no significant difference in white blood cell count in the LG filter group (10.12 ± 3.0 × 103 cells/μL pre-filtration, 10.32 ± 2.44 × 103 cells/μL post-filtration, p = 0.861). Conclusion: Our results suggest that the LG filter should not be used in ex vivo perfusion circuits for the purpose of leukodepletion. The BC2 filter can be used in EVP circuits with flow rates of less than 350 mL/min. Alternatively, perfusate may be leukodepleted before perfusion.

IntroductionEx vivo normothermic limb perfusion (EVNLP) provides several advantages for the preservation of limbs following amputation: the ability to maintain oxygenation and temperature of the limb close to physiological values, a perfusion solution providing all necessary nutrients at optimal concentrations, and the ability to maintain physiological pH and electrolytes. However, EVNLP cannot preserve the organ viability infinitely. We identified evidence of mitochondrial injury (swelling, elongation, and membrane disruption) after 24 hours of EVNLP of human upper extremities. The goal of this study was to identify metabolic derangements in the skeletal muscle during EVNLP.Materials and MethodsFourteen human upper extremities were procured from organ donors after family consent. Seven limbs underwent EVNLP for an average of 41.6 ± 9.4 hours, and seven contralateral limbs were preserved at 4°C for the same amount of time. Muscle biopsies were performed at 24 hours of perfusion, both from the EVNLP and control limbs. Perturbations in the metabolic profiles of the muscle during EVNLP were determined via untargeted liquid chromatography–mass spectrometry (MS) operated in positive and negative electrospray ionization modes, over a mass range of 50 to 750 Da. The data were deconvoluted using the XCMS software and further statistically analyzed using the in-house statistical package, MetaboLyzer. Putative identification of metabolites using exact mass within ±7 ppm mass error and MS/MS spectral matching to the mzCloud spectral library were performed via Compound Discoverer v.2.1 (Thermo Scientific, Fremont, CA, USA). We further validated the identity of candidate metabolites by matching the fragmentation pattern of these metabolites to those of their reference pure chemicals. A nonparametric Mann–Whitney U-test was used to compare EVNLP and control group spectral features. Differences were considered significantly different when P-value ResultsWe detected over 13,000 spectral features of which 58 met the significance criteria with biologically relevant putative identifications. Furthermore we were able to confirm the identities of the ions taurine (P-value: 0.002) and tryptophan (P-value: 0.002), which were among the most significantly perturbed ions at 24 hours between the experimental and control groups. Metabolites belonging to the following pathways were the most perturbed at 24 hours: neuroactive ligand-receptor interaction (P-values: 0.031 and 0.036) and amino acid metabolism, including tyrosine and tryptophan metabolism (P-values: 0.015, 0.002, and 0.017). Taurine abundance decreased and tryptophan abundance increased at 24 hours. Other metabolites also identified at 24 hours included phenylalanine, xanthosine, and citric acid (P-values: 0.002, 0.002, and 0.0152).DiscussionThis study showed presence of active metabolism during EVNLP and metabolic derangement toward the end of perfusion, which correlated with detection of altered mitochondrial structure, swelling, and elongation.

INTRODUCTION: Ex-vivo normothermic limb perfusion (EVNLP) has been proven to preserve limb viability better than standard cold storage. Perfusates containing packed red blood cells (pRBC) improve outcomes when compared to acellular perfusates. Limitations of pRBC-based perfusion include limited availability, need for cross match, mechanical hemolysis, and activation of pro-inflammatory proteins. Hemoglobin-based oxygen carrier (HBOC)-201 (Hemopure) is a solution of polymerized bovine hemoglobin, characterized by low immunogenicity, no risk of hemolytic reaction, and enhanced convective and diffusive oxygen delivery. This is a preliminary study on the feasibility of EVNLP using HBOC-201 as an oxygen carrier. MATERIALS AND METHODS: Three porcine forelimb perfusions were performed using an established EVNLP model and an HBOC-201-based perfusate. The perfusion circuit included a roller pump, oxygenator, heat exchanger, and reservoir. Electrolytes, limb temperature, weight, compartment pressure, nerve conduction, and perfusion indicated by indocyanine green angiography and infra-red thermography were monitored. Histological evaluation was performed with hematoxylin and eosin and electron microscopy. RESULTS: Three limbs were perfused for 21.3 ± 2.1 hours. Muscle contractility was preserved for 10.6 ± 2.4 hours. Better preservation of the mitochondrial ultrastructure was evident at 12 hours in contrast to crystallization and destruction features in the cold-storage controls. CONCLUSIONS: An HBOC-201-EVNLP produced outcomes similar to RBC-EVNLP with preservation of muscle contractility and mitochondrial structure.

INTRODUCTION Cranial vault surgery in children with ventricular shunts is more complex due to the possible interference of shunt location with surgical planning and increased risk of shunt related complications. The study evaluated the management of ventricular shunts during cranial vault remodeling (CVR) and subsequent outcomes and complications following CVR. METHODS An IRB-approved retrospective chart review was performed including patients who underwent CVR in presence of a ventricular shunt. Measured outcomes were number of shunt revisions following CVR, 30-day complication rate, 3-month complication rate, and post-CVR Whitaker classification. Finally, a review of the literature was performed, and our results were compared to previous reports. RESULTS Eleven patients met the inclusion criteria. Ventricular shunt was not exposed in 18%; exposed and not revised in 54%; exposed and left on a bone peninsula in 18% and simultaneously exposed and revised in 18%. Two patients experienced complications within 30-days. Three additional patients experienced complications within 3-months. An average of 2.2 shunt revisions per patient were performed following CVR. Whitaker classification was I in 7 patients, II in 1 patient and III in 2 patients. Shunt revision rate for patients undergoing CVR for hydrocephalic macrocephaly was on average of 1.2 and 1.9 for shunt-induced craniosynostosis in literature. CONCLUSIONS Cranial vault abnormalities in the presence of a ventricular shunt can be effectively treated with CVR. The presence of a shunt does not seem to interfere with final head shape. While leaving the shunt unexposed may appear less morbid, shunt related complications can still occur with this approach.

Ischemia and reperfusion injury remains a significant limiting factor for the successful revascularization of amputated extremities. Ex vivo normothermic perfusion is a novel approach to prolong the viability of the amputated limbs by maintaining physiologic cellular metabolism. This study aimed to evaluate the outcomes of extended ex vivo normothermic limb perfusion (EVNLP) in preserving the viability of amputated limbs for over 24 hours. A total of 10 porcine forelimbs underwent EVNLP. Limbs were perfused using an oxygenated colloid solution at 38°C containing washed RBCs. Five forelimbs (Group A) were perfused for 12 hours and the following 5 (Group B) until the vascular resistance increased. Contralateral forelimbs in each group were preserved at 4°C as a cold storage control group. Limb viability was compared between the 2 groups through assessment of muscle contractility, compartment pressure, tissue oxygen saturation, indocyanine green (ICG) angiography and thermography. EVNLP was performed for 12 hours in group A and up to 44 hours (24-44 hours) in group B. The final weight increase (-1.28 ± 8.59% vs. 7.28 ± 15.05%, P = .548) and compartment pressure (16.50 ± 8.60 vs. 24.00 ± 9.10) (P = .151) were not significantly different between the two groups. Final myoglobin and CK mean values in group A and B were: 875.0 ± 325.8 ng/mL (A) versus 1133.8 ± 537.7 ng/mL (B) (P = .056) and 53 344.0 ± 16 603.0 U/L versus 64 333.3 ± 32 481.8 U/L (P = .286). Tissue oxygen saturation was stable until the end in both groups. Infra-red thermography and ICG-angiography detected variations of peripheral limb perfusion. Our results suggest that extended normothermic preservation of amputated limbs is feasible and that the outcomes of prolonged EVNLP (>24 hours) are not significantly different from short EVNLP (12 hours).