Protein C deficiency in microvascular head and neck reconstruction

Multidisciplinary Practice Variations of Anti-Thrombotic Strategies for Free Tissue Transfers

Background: Venous thrombosis, the leading cause of free flap failure, may have devastating consequences. Many anti-thrombotic agents and protocols have been described for prophylaxis and treatment of venous thrombosis in free flaps. Methods: National surveys were distributed to microsurgeons (of both Plastics and ENT training) and hematology and thrombosis specialists. Data were collected on routine screening practices, perceived risk factors for flap failure, and pre-, intra-, and post-operative anti-thrombotic strategies. Results: There were 722 surveys distributed with 132 (18%) respondents, consisting of 102 surgeons and 30 hematologists. Sixty-five surgeons and 9 hematologists routinely performed or managed patients with free flaps. The top 3 perceived risk factors for flap failure according to surgeons were medical co-morbidities, past arterial thrombosis, and thrombophilia. Hematologists, however, reported diabetes, smoking, and medical co-morbidities as the most important risk factors. Fifty-four percent of physicians routinely used unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) as a preoperative agent. Surgeons routinely flushed the flap with heparin (37%), used UFH IV (6%), or both (8%) intra-operatively. Surgeons used a range of post-operative agents such as UFH, LMWH, aspirin, and dextran while hematologists preferred LMWH. There was variation of management strategies if flap thrombosis occurred. Different strategies consisted of changing recipient vessels, UFH IV, flushing the flap, adding post-operative agents, or a combination of strategies. Conclusions: There are diverse practice variations in anti-thrombotic strategies for free tissue transfers and a difference in perceived risk factors for flap failure that may affect patient management.

Outcomes in Head and Neck Free Flap Reconstruction Among Patients With a History of Venous Thromboembolism

OBJECTIVE

To investigate if a history of venous thromboembolism (VTE) is a risk factor for complications in head and neck free flap surgery by assessing outcomes among patients with a history of deep vein thrombosis (DVT) and/or pulmonary embolism (PE).

STUDY DESIGN

Retrospective cohort study.

SETTING

Single tertiary care center.

METHODS

All patients undergoing head and neck free flap reconstruction at our institution between September 1, 2006, and April 2, 2020, were assessed for inclusion. Patients with and without a history of DVT or PE preoperatively were identified and grouped for comparison. Groups were compared for demographics, comorbidities, and 30-day complications. Significance was assessed with chi-square and binary logistic regression analyses.

RESULTS

Of the 1061 patients meeting inclusion criteria, 40 (3.8%) had a history of VTE. These patients were significantly older (mean [SD], years: 67.8 [11.7] vs 63.0 [14.1], P = .038) and significantly more likely to have history of chemotherapy (35.0% vs 18.7%, P = .010) and stroke (27.5% vs 4.5%, P < .001). After accounting for patient characteristics via binary logistic regression, VTE was independently associated with an increased risk for postoperative thrombosis of the free flap pedicle (odds ratio [95% CI] = 3.65 [1.12-11.90], P = .032) and reoperation (2.45 [1.25-4.80], P = .009). Patients with history of PE had a significantly increased risk for flap failure (7.70 [1.77-33.52], P = .007). Prior VTE was not independently associated with an increased risk for medical complications or readmission.

CONCLUSION

Patients with a history of VTE may be at an increased risk for free flap compromise secondary to postoperative pedicle thrombosis. This risk should be considered in preoperative workup and postoperative monitoring.

Rotational Thromboelastometry Derivative Fibrinogen-Platelet Ratio Predicts Thrombosis in Microsurgery

BACKGROUND

 Early detection of thrombotic events is of paramount importance for microsurgical procedures. Here, we present findings that underscore the value of rotational thromboelastometry (ROTEM) to aid in decision-making for pre- and postoperative anticoagulation, as well for patients with suspected hypercoagulability.

METHODS

 We prospectively collected pre- and postoperative ROTEM values on all free flap cases at the University of California, San Francisco, from 2015 to 2016. Patient age, body mass index, comorbidities, operative reports, risk factors, thrombotic complications, and outcomes were collected from electronic medical records. Two-sample t-tests were used to compare ROTEM values between cohorts. Modeling for sensitivity, specificity, and accuracy was done for threshold fibrinogen-to-platelet ratio (FPR).

RESULTS

 Of 52 patients who underwent free-tissue transfer, 15 had a thrombotic event either intraoperatively or postoperatively that required revision of the vascular anastomosis. Eight patients were clinically hypercoagulable preoperatively, seven of which had a thrombotic event. Several pre- and postoperative ROTEM values differed significantly between thrombotic and nonthrombotic cases. Preoperative (p = 0.027) and postoperative (p = 0.013) FPR were statistically significant when comparing the thrombotic to the nonthrombotic cohort. Threshold FPR ≥ 30 was the most sensitive and FPR ≥ 40 was the most specific.

CONCLUSION

 Our study affirms other studies that established ROTEM as an effective predictive tool for thrombotic events during free-tissue transfer. However, a lower threshold for FPR improves catchment of thrombotic events and flap failure with acceptable sensitivity. Our results support the routine use of ROTEM for detecting hypercoagulability in patients who would potentially benefit from intervention to prevent thrombotic complications.

Effects of endothelial defects and venous interposition grafts on the acute incidence of thrombus formation within microvascular procedures

Endothelial defects (ED) and the usage of interposition vein grafts (IVG) are known risk factors for free flap failure. This experimental study aimed to compare both situations of thrombus formation and fluorescence angiographic behavior. Indocyanine green videoangiography (ICGVA) with the FLOW 800 tool was systematically performed in groups I = ED, II = IVG, and III = ED and IVG (each n = 11). ICGVA was able to detect thrombosis in five animals and safely ruled it out in 26 with two false-positive cases (sensitivity, specificity, and positive and negative predictive values were 100%, 90%, 62%, and 100%, respectively). The difference between visually and ICGVA-assisted ED measurements was significant (p = 0.04). The areas of thrombosis showed no significant difference. Moreover, ICGVA detected a decrease of all parameters at the ED area and/or within the IVG section in all groups. The presence of an endothelial defect had a higher impact on thrombus formation than the IVG usage. ICGVA is qualitatively able to detect endothelial defects and clinically evident thrombosis. However, the quantitative values are not yet attributable to one of the clinical scenarios that may jeopardize free flap transfer.

Maxillofacial and oral surgery in patients with thrombophilia: safe territory for the oral surgeon? A single-center retrospective study

OBJECTIVE

The aim of this study was to analyze patients with thrombophilia who underwent oral and/or maxillofacial surgery at our center.

STUDY DESIGN

We performed a retrospective analysis of patients with hereditary or acquired thrombophilia who had undergone oral/maxillofacial surgery between January 1, 2000 and December 31, 2019. Data regarding demographic and patient characteristics, surgical treatment modalities, antithrombotic therapies, and complications were analyzed.

RESULTS

A total of 76 eligible patients (26 male, 50 female) were included in this study, with a mean follow-up period of 3.8 months (range, 0-51 months). The mean age at time of surgery was 44.7 ± 19.4 years. Seven different hereditary and acquired thrombophilia were identified: factor V Leiden (n = 31; 40.8%), prothrombin G20210A mutation (n = 5; 6.6%), protein C deficiency (n = 4; 5.3%), protein S deficiency (n = 11; 14.5%), antiphospholipid syndrome (n = 10; 13.2%), hyperhomocysteinemia (n = 8; 10.5%), and elevated factor VIII (n = 2; 2.6%). Complications occurred in 9 patients (11.8%) and included postoperative infections (n = 6; 7.9%) and postoperative bleeding (n = 3; 3.9%).

CONCLUSION

Our data suggest that oral and/or maxillofacial surgery in patients with a confirmed diagnosis of thrombophilia is not associated with a burden of thrombosis or high complication rates. Furthermore, we formulated a guideline for preoperative antithrombotic therapy for patients with thrombophilia undergoing oral and/or maxillofacial surgery.

Comparison of the surgical outcomes of free flap reconstruction for primary and recurrent head and neck cancers: a case-controlled propensity score-matched study of 1,791 free flap reconstructions

This study was designed to compare the outcome and analyze the operation-related risk factors in free flap reconstruction for patients with primary and recurrent head and neck cancers. A 1:1 propensity score-matched analysis of the microsurgery registry database of the hospital. The primary outcome of the free flap reconstruction had a higher failure rate in the recurrent group than the primary group (5.1% vs. 3.1%, p = 0.037). Among the 345 pairs in the matched study population, there were no significant differences between the primary and recurrent groups regarding the rate of total flap loss (3.5% vs. 5.5%, p = 0.27) and secondary outcomes. This study revealed that free flap reconstruction had a higher failure rate in the recurrent group than the primary group, but such a difference may be attributed by the different patient characteristics.

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.

Markers of blood coagulation and fibrinolysis in patients with early and delayed microsurgical reconstructions in the lower extremities

BACKGROUND

In this study, markers of coagulation and fibrinolysis were assessed during early and delayed microsurgical reconstruction in patients with traumatic defects of their lower legs to analyse whether an imbalance of the hemostasis after trauma might predispose the development of vascular complications.

METHODS

The prospective study included 70 patients. In 35 patients, surgery was performed within 72 hours after injury. In 35 other patients, delayed free flap transfer was performed between 14-21 days after trauma. In each group, reconstruction was performed with a fasciocutaneous anterior-lateral thigh flap (ALT, n = 18) or a myocutaneous flap (latissimus dorsi flap; n = 17). Blood samples were collected preoperatively, intraoperatively, and 3, 6, 12, 24, 36, 48, 72, 96 and 120 hours after the operation. Analysed parameters included markers of coagulation such as prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin III-complex (TAT), and antithrombin, as well as fibrinolysis markers such as plasminogenactivator inhibitor-I (PAI-1), tissue-plasminogenactivator (t-PA), and plasminogen.

RESULTS

Preoperatively, levels of F1 + 2, TAT, and PAI-1 were significantly higher in patients with delayed reconstruction (p < .05). Patients with later vascular complications in this group (n = 5) presented a significant higher concentration of TAT, F1 + 2, and PAI-1 (p < .05). Twelve and 24 hours after free flap surgery, patients with vascular complications presented significant elevated levels of these markers (p < .05).

CONCLUSIONS

Patients with delayed free flap surgery after lower leg trauma present a hypercoagulable state in their blood due to activation of the coagulation system and hypofibrinolysis. Early reconstruction might minimise the risk of flap failure caused by hypercoagulability.

Indocyanine green videoangiography-assisted prediction of flap necrosis in the rat epigastric flap using the flow® 800 tool

BACKGROUND

The decision to re-operate on a potentially ischemic free flap remains challenging. Indocyanine green videoangiography (ICG) with the FLOW^® 800 tool is a method which allows an immediate qualitative conclusion about the patency of an anastomosis. Is it also able to predict the outcome of potentially compromised vascular free flaps?

MATERIALS AND METHODS

An epigastric flap was raised and repositioned in 79 rats. Intraoperative fluorescence angiography was performed using ICG videoangiography and the FLOW^® 800 tool was applied. Six regions of interest were positioned systematically over the flap, changes of the ICG fluorescence were color coded with respect to time and 474 measurements were performed. The flap was clinically monitored for one week and the resulting necrotic areas were correlated with the ICG/FLOW^® 800 results.

RESULTS

Mean intensity of clinically vital areas was 83.39 ± 50.96 arbitrary units (AU) and 37.33 ± 15.14 AU in necrotic areas. The receiver operating characteristic curve and Youden-Index analysis revealed that the optimal cutoff for the maximal intensity of ICG after FLOW^® 800 analysis was ≤ 61.733 for the prediction of flap necrosis and > 61.733 for the prediction of flap survival (P < 0.0001; 95% CI = 0.85-0.91; Youden-Index: 0.67). The maximal intensity of ICG angiography had a specificity of 96.1% and sensitivity of 71.4%. The positive predictive value was 97.46% and the corresponding negative predictive value was 61.34%.

CONCLUSION

This demonstrates the potential additional value of ICG videoangiography including FLOW^® 800 analyses in the postoperative monitoring of transplanted flaps. © 2016 Wiley Periodicals, Inc. Microsurgery 37:235-242, 2017.

Microsurgery and the Hypercoagulable State: A Hematologist's Perspective

Hypercoagulability can pose a significant problem in microsurgical reconstruction. Here, the authors provide a comprehensive review of macrovascular and microvascular clotting phenomena from the unique viewpoint of two microsurgeons and a hematologist. The authors review the literature surrounding prevention of microvascular clots and provide an extensive discussion of hereditary thrombophilia. The authors also make explicit recommendations regarding the utility of thrombophilia testing and preoperative and perioperative management strategies for patients with hypercoagulability.

An overview of coagulation disorders in cancer patients

A diversity of coagulation disorders in cancer patients arise from tumor-specific growth characteristics, neoangiogenesis with impaired endothelial lining, defective myelopoiesis, hypoproteinemia or metastatic lesions growth with organ dysfunction. Recent investigations have found a clinically relevant correlation of coagulation disorders and tumor growth. These prompted new therapeutic strategies focused on growth factors with the aim to control tumor metastasis, particularly if used for the treatment of micrometastatic disease. However, such treatment may lead to the life threatening coagulation imbalance. A coagulation homeostasis may become further impaired after nonsurgical cancer therapy, especially after preoperative irradiation, which produces lesions precipitating both bleeding and thrombosis. Anticancer chemotherapy may affect liver function and decrease the synthesis of both procoagulation and anticoagulation factors. The most of chemotherapeutic protocols affect platelet synthesis, which arises as a principal dose-limiting side effect. It was observed both during combined systemic chemotherapy and local antitumor therapy. Although the side effects produced by chemotherapy are reversible, endothelial lesions may persist for many years after the anticancer treatment. Instead of cancer patients, there's a growing cohort of patients with nonmalignant diseases who use cytostatics in the perioperative period, and are candidates for surgical procedures not related to their malignant disease, i.e. hernia repair. In this patient population a special attention must be paid to the preoperative evaluation of coagulation status and thromboprophylaxis. This overview reminds the most common coagulation disorders in cancer patients in the perioperative period. It emphasizes the need for proper patient monitoring which may facilitate the diagnostics and treatment of cancer-related coagulation disorders in the perioperative setting.

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.

Critical care of the head and neck patient

The patient with head and neck disease has several peculiarities that need to be recognized for the treating team to offer optimal care. These arise from the primary disorders (eg, head and neck cancer or injuries) and the morbidity they might cause, the associated comorbidities, and the possible complications of treatment. A team approach involving the surgeon, the intensivist, and other caretaking personnel is essential to achieve high-quality care and ensure the best results possible.