Abstract
Introduction: Coagulation assessment is often missing in microvascular surgery. We aimed at evaluating the predictive value of thromboelastometry for free flap thrombosis in microvascular surgery patients.Materials and Methods: We enrolled 103 adult patients with traumatic injuries scheduled for microvascular free flap surgery into a prospective observational study. Thirty-six patients with recent trauma underwent surgery within 30 days (ES group), and were compared with 67 trauma patients who underwent surgery later than 30 days (late surgery, LS group) after the injury. Rotational thromboelastometry (RTE) was performed before surgery. Functional fibrinogen to platelet ratio (FPR) ≥ 42 was selected as the main hypercoagulability index. Free flap thrombosis was set as primary outcome. Thrombotic risk factors and duration of surgery related to free flap thrombosis were secondary outcomes. Statistical significance p < 0.05; not significant NS.Results: Six patients (16.7%) in the ES group and 10 (14.9%) in the LS group had free flap thrombosis (NS). In the entire cohort, free flap thrombosis rate increased in the presence of thrombogenic comorbidities (OR 4.059, CI 1.33–12.37; p = 0.014) and prolonged surgery times (OR 1.007, CI 1 – 1.012; p = 0.05). Although hypercoagulability occurred more frequently in the ES group (44.4%) than in the LS group (11.9%; p < 0.001), it was not associated with higher free flap thrombosis rate. In ES group patients with surgery times > 240 min, the risk of free flap thrombosis increased (OR 3.5, CI 1.16-10.6; p = 0.026) with 93.3% sensitivity and 86.7% specificity (AUC 0.85; p = 0.007). In contrast, in LS patients hypercoagulability increased the odds of free flap thrombosis (OR 8.83, CI 1.74–44.76; p = 0.009). Moreover, a positive correlation was found between FPR ≥ 42 and free flap thrombosis rate (r = 0.362; p = 0.003). In the LS group, the presence of thrombogenic comorbidities correlated with free flap thrombosis rate (OR 7, CI 1.591–30.8; p = 0.01).Conclusions: In LS patients with thrombogenic comorbidities, thromboelastometry supports the detection of hypercoagulability and predicts free flap thrombosis risk. In ES patients, postoperative hypercoagulability did not predict free flap thrombosis. Prolonged surgery time should be considered as a risk factor.
Highlights
Coagulation assessment is often missing in microvascular surgery
Microvascular free flap thrombosis most often occurs secondary to technical mishaps and/or longer duration of surgery [7], a number of other preoperatively identifiable factors have a potential impact on anastomotic thrombosis rate and outcome of tissue transfer [8,9,10]
There were no significant differences in smoking history, thrombocytosis or surgery time between the groups
Summary
We aimed at evaluating the predictive value of thromboelastometry for free flap thrombosis in microvascular surgery patients. Since the introduction of free tissue transfer, advancements in microsurgical techniques have increased flap survival rates [1,2,3]. Despite technical progress, free flap thrombosis still remains a matter of concern [4, 5] because it is associated with higher morbidity, increased costs and, longer hospital stay. Microvascular free flap thrombosis most often occurs secondary to technical mishaps and/or longer duration of surgery [7], a number of other preoperatively identifiable factors have a potential impact on anastomotic thrombosis rate and outcome of tissue transfer [8,9,10]. Patient - related factors, such as hereditary or acquired hypercoagulability [11,12,13,14], age [8], diabetes mellitus [15, 16], poor nutritional status [17], cardiovascular diseases [6, 18] or autoimmune disorders [11] were all demonstrated to affect negatively the outcomes of tissue transfer surgery
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