Vascular complications after free tissue transfer

Dextran-40 Reduces Partial Flap Failure: A Systematic Review and Meta-analysis for Antithrombotics after Free Flaps

Background

Antithrombotic agents are used after free-flap surgery to prevent thrombus formation and improve flap outcomes. However, the reports vary. Therefore, this meta-analysis aimed to elucidate the need for antithrombotic agents in this context.

Methods

We searched for studies that compared the outcomes of patients undergoing free-flap surgery with or without postoperative antithrombotic agents in the PubMed, Cochrane, and ClinicalTrials.gov databases. The primary outcome was total flap failure, with secondary outcomes including partial flap failure, pedicle thrombosis, and bleeding/hematoma. The relative risks (RRs) of outcomes with or without antithrombotic use were evaluated.

Results

Fifteen studies (n = 6755 cases) were included. Antithrombotic agents did not reduce flap failure or pedicle thrombosis risks but increased bleeding and hematoma risks (RR, 1.535). Subgroup analyses by antiplatelet and anticoagulant use demonstrated results similar to those of antithrombotic use. The RR of bleeding/hematoma was 1.761 and 2.740 in the antiplatelet and anticoagulant groups, respectively. Postoperative dextran-40 administration reduced the risk of partial flap failure, with an RR of 0.535.

Conclusions

Postoperative antithrombotic, antiplatelet, or anticoagulant use did not change the risk of total/partial flap failure or pedicle thrombosis but increased the risk of hematoma/bleeding. Postoperative use of dextran-40 reduced the risk of partial flap failure. Increased intraflap blood flow may decrease the risk of partial flap failure. However, dextran-40 may cause severe pulmonary distress. Further prospective studies are required to evaluate the effects of these agents on thrombus formation, intraflap blood flow, and partial flap failure risk.

Assessment of perfusion of free flaps used in head and neck reconstruction using pulsatility index

Objective:

To detect venous or arterial obstruction in the pedicle of a free flap we can monitor resistance in the flap bed which is reflected in Pulsatility Index (PI) Therefore if we detect change in the values of the PI in these flaps then we can detect complications in flap due to vascular insufficiency early.

Materials and Methods:

Seven patients of Free Fibular Flap Reconstruction and ten patients of Free Radial Forearm Flap reconstruction were evaluated over a period of 18 months. In the pre op we recorded PI of Radial and Peroneal artery using colour doppler study. In the Post Operative Period 2 readings of PI at the anastomotic site were taken on Day 1 and Day 7.

Results:

Both Free Radial Forearm and Free Fibula flaps which were healthy (n = 15) showed a significant decrease in PI values on first Post Op day as compared to Pre Op. Also there was a significant fall in PI on Post Op Day 7 as compared to post op Day 1 (P < 0.05) in these flaps. The flaps developing complications (n = 2) had significantly higher Day 1 Post op PI readings as compared to healthy flaps (P < 0.05).

Conclusion:

PI is an objective index which can indicate changes in perfusion of free flaps used in Head and Neck reconstruction based on which we can predict if a flap is susceptible to circulatory compromise.

The outcome of prostaglandin-E1 and dextran-40 compared to no antithrombotic therapy in head and neck free tissue transfer: analysis of 1,351 cases in a single center

Free tissue transfer has become a popular technique for soft tissue defect reconstruction in head and neck cancer ablation. Although high success rates and good reliability of free flaps are proven, microvascular thrombosis is still the most critical issue for microsurgeons. Pharmacological antithrombotic agents are widely used but their efficacy is still debated. In this study, we analyzed whether prostaglandin-E1 (PGE1) and dextran-40 can improve the outcomes compared to no antithrombotic therapy at all. We retrospectively reviewed 1,351 free flaps performed for head and neck reconstruction after cancer ablation. Three groups defined were 232 flaps received PGE1, 283 flaps received dextran-40, and 836 received no antithrombotic therapy. The demographics of these three groups indicated no statistical differences. The results showed that flap survival revealed no significant difference among PGE1, dextran-40, and control group (P = 0.734). There was a tendency to hematomas in PGE1 group (P = 0.056) when compared with other two groups. Dextran-40 significantly increased flap failure rate in high-risk patients with diabetes mellitus (P = 0.006) or hypertension (P = 0.003), when compared with PGE1 and control group. These results revealed antithrombotic therapy with PGE1 and dextran-40 do not determine a significant improvement in flap survival.

Multiple spurting test in microsurgical reconstruction of the lower extremities

Appropriate recipient artery is essential for the success of free flap reconstruction, however the selection could be difficult in a traumatized lower extremity. To detect unnoticed damage of the recipient artery, vascular integrity should be verified. For that purpose, we propose a simple and effective evaluation method, called Multiple Spurting Test (MST) this test esteems the dynamic status of the recipient arteries by measuring the length of arterial spurting. All the microsurgeons usually do something like MST: but it is not a standardized test yet.This study analyzed if this test could be a practical method in searching a safe recipient artery during microsurgical reconstruction of lower extremity. MST was employed in 163 flaps, all for lower extremity reconstruction. Fifteen flaps were re-explored in this series. Six of them had arterial problems, three in Anterior Tibial Artery (ATA), two in Posterior Tibial Artery (PTA) and one in Sural Artery (SA). The overall series' re-exploration rate, due to different complications, was 7% when ATA has been the recipient vessel, 7.6% with PTA and 30.7% with SA. Both ATA and PTA found equally reliable after examination with MST. We do believe that MST can effectively decrease the incidence of arterial complications and flap failure. Using this method, it is easier to choose a safe recipient artery for revascularization.

Activated protein C resistance due to factor V Leiden, elevated coagulation factor VIII and postoperative deep vein thrombosis in late breast reconstruction with a free TRAM flap: a report of two cases

Thromboembolic complications can endanger free flap surgery and cause postoperative morbidity and even mortality. The underlying cause of thrombosis is multifactorial; major surgery may trigger hereditary thrombophilic disorders leading to overt thrombotic events. This paper reports two cases with postoperative deep vein thrombosis after late breast reconstruction with a TRAM flap. Both showed APC resistance due to factor V Leiden and elevated coagulation factor VIII. One of the patients also had an event of both arterial and venous anastomotic thrombosis postoperatively.

Salvage of free flaps after venous thrombosis: Case report

Venous thrombosis of a free flap is a serious complication in microsurgery. Several agents with the ability to dissolve an occluding thrombus exist. Recombinant tissue plasminogen activator (rt-PA) seems the most effective. We present our experience with a procedure that was successful in elimination of the occluding thrombus in two patients.

Free flap monitoring using an implantable Doppler probe

Although clinical observation is the gold standard, the ideal free flap monitoring device has not been identified. The purpose of the present study was to review the first 14 months of experience using an implantable 20-MHz ultrasonic Doppler probe to monitor the microvascular anastamoses of free tissue transfers. Twenty-five flaps in 23 patients, with an average age of 51 years (age range 18 to 81 years), were performed. Probes were secured downstream of the venous anastamosis using a silicone-poly fluorotetraethylene sleeve. Doppler sounds were transduced before the flap was inset. Monitoring by nursing staff included conventional techniques (temperature, colour, capillary refill) and continuous Doppler flow monitoring. Dynamic diagnostic testing for anastomotic patency was facilitated by applying manual pressure on the flap to increase venous flow (the audible ‘whoosh’ sign) and valsalva manoeuvre to impede venous return momentarily (the ‘heave’ sign). Intraoperative vessel kinking, hematoma formation occluding venous outflow, and venous thrombosis were detected in four cases before concluding the procedure and corrected. Rapid, immediate cessation of audible flow was detected postoperatively in three of 25 flaps. Re-exploration (re-exploration rate 12%) led to salvage of all three flaps (salvage rate 100%). It was concluded from this study that flap re-exploration was prevented in four cases (16%) because of intraoperative use of the implantable Doppler probe. Earlier detection of flap compromise perioperatively is thought to have contributed to the 100% salvage rate and to the 100% flap survival rate in the first 25 cases in which the implantable Doppler probe was used.

Activation of coagulation and fibrinolysis in microsurgical reconstructions in the lower extremities

Coagulation and fibrinolysis activities in relation to trauma, surgery and thrombosed microanastomoses were studied during free-flap surgery in eight patients with lower-extremity defects due to recent trauma or chronic ulcers. One patient had an intraoperative thrombosis, and three more patients required reoperations on the same day due to postoperative thromboses; one of these also required a second reoperation due to flap failure. The baseline level of fibrinogen was slightly elevated in all patients except one, and was significantly higher in the patients who underwent reoperation. At the end of the primary surgery, distinct thrombin generation (TAT and F1+2) was seen in three patients with excessive bleeding, and all three later underwent reoperations. One of these patients generated excessive thrombin on the eighth postoperative day, upon removal of a necrotic flap. Thrombin generation (F1+2) was also seen at baseline in the patient with the intraoperative thrombosis, and persisted on the first postoperative day. D-dimer at baseline was higher in patients with recent trauma, and in two of these, both of whom underwent reoperations on the same day, D-dimer remained high perioperatively. Resistance to fibrinolysis with increased PAI-1 levels was seen in these two patients at the time of reoperation. In all, TAT and F1+2 were associated with the threat of flap failure. A preoperative hypercoagulable state and excessive bleeding during the operation were predictors of reoperation. The markers for coagulation and fibrinolysis could be used preoperatively to target antithrombotic control, and postoperatively to detect the threat of flap failure. Meticulous haemostasis during surgery might help to diminish the need for reoperations.

Immunohistochemical evaluation of failed vessel anastomoses in clinical microsurgery

Failed vessel anastomoses collected from 12 patients during elective free flap surgery, and from one patient after failed mid-hand replantation were subjected to immunohistochemical analysis. The anastomotic failure was due to an obvious thrombosis, poor flow, an excessively sharp pulse or some other reason causing a non-functioning anastomosis. A total of 17 samples were obtained, 13 of them arterial, three between the artery and vein graft, and one venous. The majority of samples were resected during primary surgery and four of them at reoperation. Variables of coagulation and fibrinolysis were analysed repeatedly during the operation in 7/13 patients. Total occlusion was seen in 6/17 samples and a non-occlusive thrombus in 4/17; two of these were due to suture error. Immunohistochemistry showed that, overall, the endothelial cells (PECAM-l, CD 31) were absent and that the staining pattern for platelets (CD 42b and CD 31) and fibrin (fibrin II, T2G1) correlated. In the absence of a thrombus, however, adherent platelets were positive only for CD 42b, not for PECAM-1. Vessel inflammation was a prominent feature at reoperations. Analysis of coagulation and fibrinolytic markers (thrombin-antithrombin III complex, prothrombin fragment 1 + 2 and D-dimer) confirmed the occurrence of thrombosis in three patients undergoing breast reconstruction with clinically obvious thrombosis during primary surgery or at reoperation. Moreover, the patients with active cancer (2/7) were clearly hypercoagulable compared with the other patients. In short, the primary anastomotic failure was associated with loss of endothelial cells, and with co-localised platelet recruitment and fibrin formation at these sites. At reoperation, inflammation was a prominent feature at the vessel site of thrombi.

Local recombinant tissue plasminogen activator (rt-PA) thrombolytic therapy in microvascular surgery

Vascular thrombosis remains a dreaded complication of any microvascular procedure, be it composite tissue transfer or replantation of amputated limbs or parts. Despite the tremendous advances in microvascular-related technologies and the accumulated surgical skills, failures caused by occlusion of anastomosed vessels remain a continuous source of frustration to all microsurgeons alike. Several anticoagulation and antiplatelet protocols have been proposed to be used in conjunction with microvascular surgery. More recently, thrombolytic drugs such as urokinase, streptokinase, and thrombolysin have been introduced, yet their systemic effect on hemostasis remains an undesirable side effect. We present our experience with local intra-arterial, intravenous, and soft-tissue injection of recombinant tissue plasminogen activator rt-PA in replantation surgery in three consecutive patients. Arterial thrombi are managed by intra-arterial rt-PA infusion with the catheter placed proximal to the arterial anastomosis. Venous thrombi are best lysed by infusing rt-PA in an engorged vein of the replanted limb. In replanted digits, direct intravenous infusion is not possible. In such situations, injection of rt-PA in the pulp soft tissues may result in successful salvage. We believe this agent also has a role in microvascular composite tissue transfer in preventing free flap failures as well as in salvaging failing flaps.

Effect of ischemia and reperfusion on neutrophil accumulation in equine microvascular tissue flaps

OBJECTIVE

To investigate neutrophil accumulation after ischemia and reperfusion (IR) in microvascular tissue flaps in horses.

STUDY DESIGN

Randomized controlled experiment.

SAMPLE POPULATION

A total of 8 horses between 1 and 10 years of age, 4 of each sex.

METHODS

Control and experimental myocutaneous island flaps based on the superficial branch of the deep circumflex iliac vessels were dissected on each horse. Atraumatic vascular clamps were applied to the pedicle of the experimental flap for 90 minutes and then removed to allow reperfusion. Based on the assumption that rapid infiltration of neutrophils into affected tissues is a hallmark of IR injury, radiolabeled autogenous leukocytes were used to indirectly quantify neutrophil accumulation in flap tissues. Labeled leukocytes were administered through a jugular catheter 30 minutes before flap reperfusion. Biopsies were collected from each flap over a 6 hour postischemia time period; in group 1 (n = 4) from 0 to 6 hours postischemia, and in group 2 (n = 4) from 24 to 30 hours postischemia. Biopsies were examined scintigraphically and histologically for evidence of neutrophil infiltration.

RESULTS

All control flaps survived and 6 of 8 experimental flaps survived. There was no significant evidence of acute neutrophil infiltration into flap tissues after reperfusion in either group.

CONCLUSIONS

The results of this study suggest that equine myocutaneous flap tissues can survive a 90-minute ischemic period and reperfusion. No significant evidence of the occurrence of IR injury in flap tissues was found.

CLINICAL RELEVANCE

The reasons for the previously reported failures of equine free tissue transfer remain uncertain, but they do not appear to be caused by neutrophil mediated injury associated with ischemia and reperfusion.

Ischemic preconditioning improves the survival of skin and myocutaneous flaps in a rat model

Inadequate blood supply of pedicle flaps results in partial necrosis, and prolonged ischemia during free-tissue transfer can result in partial or complete flap necrosis. Recent research in the field of cardiovascular surgery has shown that ischemic preconditioning (repeated brief episodes of coronary artery occlusion followed by reperfusion) improves myocardial muscle survival when the heart is subsequently subjected to prolonged ischemia. Preconditioning of skin or myocutaneous flaps as either pedicle or free flap models has never been studied. The goal of this investigation was to measure the effect of ischemic preconditioning on myocutaneous and skin flap survival areas and total necrosis rates after variable periods of global ischemia. In 220 rats, 100 transverse rectus abdominis myocutaneous flaps and 120 dorsal cutaneous flaps were randomized into treatment and control groups. The treatment flaps underwent preconditioning by three cycles of 10 minutes of pedicle clamping followed by 10 minutes of reperfusion for a total preconditioning period of 1 hour. The control flaps were perfused without clamping for 1 hour. Both control and treatment flaps then underwent global ischemia for 0, 2, 4, 6, 10, or 14 hours by pedicle clamping. Flap survival area was measured on the fifth postoperative day. Statistical analysis was performed with analysis of variance, student's t tests, and probit analysis. Preconditioning improved survival areas of pedicle myocutaneous flaps (0-hour group) from 47 +/- 16 percent (mean percent area surviving +/- SD) to 63 +/- 5 percent. This difference was statistically significant (t test, p < 0.04). There was no statistically significant improvement in pedicle skin flap survival. For free flap models (flaps undergoing global ischemia), preconditioning increased the survival areas of skin and myocutaneous flaps (analysis of variance, p < 10(-5)). For the skin flap model, statistical significance of the survival area difference was reached at 6, 10, and 14 hours of ischemia (t test, p < 10(-4)). The magnitude of this effect was higher in the myocutaneous flap model and reached statistical significance at 2, 4, 6, and 10 hours of ischemia (p < 10(-3)). Preconditioned flap survival areas were increased by two to five times that of non-preconditioned flaps at these ischemia times. Preconditioning lowered total necrosis rates at all ischemia times for both flap models. The critical ischemia time when 50 percent of skin flaps became totally necrotic (CIT50) improved from 6.9 to 12.4 hours by preconditioning. Similarly, preconditioning improved the CIT50 of myocutaneous flaps from 3.6 to 9.2 hours. For the first time, statistically significant improvements of partial necrosis areas and total necrosis rates have been demonstrated through intraoperative ischemic preconditioning of skin and myocutaneous flaps. In clinical practice, application of this technique may lead to improved survival during pedicled or free transfer of myocutaneous flaps and free transfer of skin flaps.