Risk factors and blood flow in free TRAM flap Discussion This clinical study shows that smoking, especially in patients with a high flap weight, leads to a reduction in microcirculatory blood flow of the free TRAM flap. Clinical outcome also revealed a significant increase in FC in smokers, as well as in obese patients. Preoperative radiotherapy and chemotherapy did not alter the blood flow or the clinical outcome. Age did not affect clinical outcome and was, interestingly, associated with an increased blood flow in zone IV after reperfusion. This increased blood flow lasted for the whole study period. The age groups used in this study were not related to any of the other risk factors investigated in this study. Analysis of hemodynamics, which was monitored for the first 24 hours, revealed similar mean arterial pressure but an increased heart rate in older patients. Whether this increased heart rate may be the cause of increased blood flow remains to be seen. Several studies focusing on free flap surgery in older patients have shown that age is not a significant risk factor and that age alone should not be considered as a risk factor. However, age did affect the rate of medical complications in some studies.33,34 These medical complications are probably due to the status and comorbidity of other systemic diseases in these patients. Serletti et al.34 showed that physical status (ASA score) and duration of the operation are the significant predictors of postoperative morbidity. Therefore, with careful preoperative assessment and perioperative monitoring, high age alone should not be considered as a contraindication. Smoking has long been known to be associated with disturbed wound‐healing complications such as dehiscence and infection. The greatest risk for these complications is in wounds with wide surgical undermining such as abdominal flaps and facelifts.35 These problems have also been reported in pedicled and free TRAM flap procedures.36,37 In a previous study, we have shown that the viability of zone IV depends on the increase in blood flow to this region of the flap.24 Smoking leads to an impairment of microvascular function.38 Therefore, smoking may impair the vasodilatory responses within the TRAM flap to zone IV during the flap acclimatization period. This theory is confirmed in this study by the reduced increase in blood flow which was observed in smokers. Reports in the literature show that these complications could be reduced by a cessation of smoking well in advance (3–4 weeks) of surgery.36,37 Although obesity was associated with an increase in FC, a high flap weight was not associated with a reduced blood flow. The percentage of the original abdominal flap used for reconstruction was also not associated with a reduced blood flow. However, patients with both smoking and a high flap weight compared with patients without both these risk factors showed even more clearly increased significance in the reduced blood flow in zone IV compared with smoking alone. Therefore, the inclusion of zone IV in especially these patients leads to a reduction in blood flow and increase in clinical 81
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