Avoiding Complications

Fitness for Anesthesia

As with all major surgery, cardiac and respiratory fitness should be appropriate before electing a microsurgical case. Prolonged awkward postures need to be tolerated, which may temper the choice of donor flap and extent of operation. A personal or family history of thrombosis should be especially sought in the preoperative screening and consideration given to preoperative anticoagulation in routine cases.

Age

Age per se is not a contraindication to microvascular surgery. A number of studies have shown no difference in free flap survival when extremes of age are evaluated. Pediatric patients have excellent free flap survival rates, with very few nonsurgical complications and no apparent growth-related complications noted at donor or recipient sites, although research indicates exposure to anesthesia before 3 years of age may result in cognitive deficits. Prospective studies on this are still ongoing. Although excellent flap survival rates are observed in patients of advanced age, 75% of patients older than 70 years have more than one medical issue contributing to complications such as myocardial infarction, pulmonary embolism, and prolonged intubation. In one series, mortality was as high as 5.4% in the age group 60–69 years with significant preoperative medical. In other reports, although medical complications were very high, mortality was much lower.

Systemic Disease

Diabetic patients do not seem to experience a higher incidence of free flap thrombosis and/or failure. Most of the robust research on diabetic free flaps has been reported in the lower extremity with success rates around 92%. Numerous reports show the importance of tight glucose control pre- and postoperatively to minimize surgical morbidities in diabetic patients. Data from our institution show poor long-term glycemic control in patients with an HbA _1c >6.5% leads to increase in wound dehiscence. Hypercoagulable patients should be managed in conjunction with hematology, as these patients have a much higher rate of thrombosis and a lower rate of free flap salvage. It is important to take a thorough history of previous deep venous thrombosis (DVT), multiple miscarriages, or a family history of blood clotting abnormalities. Obesity alone does not appear to be associated with increased free flap failure rates, although the incidence of hematoma or hemorrhage appears to be higher. A recent meta-analysis of free autologous breast reconstruction showed that patients with a BMI >40 had a much higher prevalence of complications compared with non-obese patients.

Tobacco Smoking

The influence of smoking on the outcome of microvascular surgery is a contentious issue. The detrimental effect of nicotine on cutaneous blood flow and wound healing is accepted. Chang and Buncke reported an extraordinarily detrimental effect of smoking on replantation surgery outcomes, stating that 80% of patients who smoke in the period between 2 months before and 2 months after surgery can be expected to lose their replants. Our experience does not support this low survival rate.

The effect of smoking on free tissue transfer outcomes is less clear. Although numerous experimental studies have linked cigarette smoking with delayed microvascular anastomotic healing and free flap failure, we demonstrated significant reductions in blood flow without reductions in microvascular anastomotic patency in animal models following nicotine administration. Furthermore, a number of large clinical studies have demonstrated no significant difference in vessel patency, flap survival, or reoperation rates in smokers compared with non-smokers. Of interest, perforator free flaps may differ from traditional free tissue transfers in that reoperation rates, and anastomotic complications appear to be higher in smokers than non-smokers. It is our practice to recommend that smokers undergoing elective reconstruction cease smoking at least 2 weeks before the procedure, and refrain from smoking for at least 2 months postoperatively. We have several anecdotal cases of both digits and flaps undergoing irreversible arterial spasm as a direct consequence of smoking.

Site and Cause

The site of the defect for reconstruction has not been shown to significantly predict survival or microvascular complications in free flap surgery. In particular, free tissue transfer to defects of the lower extremity does not seem to have a higher incidence of complications than to other sites. Similarly, outcomes do not seem to be predicted by the condition requiring reconstruction, whether it be trauma, chronic wound, osteomyelitis, congenital anomaly, burns, cancer, or other condition. With respect to trauma, this is inconsistent with the reports of Godina and Byrd et al., who convincingly showed that complications were higher and flap survival less when free flaps were transferred to compound lower-leg wounds after the first week of injury. Empirically, if there is poor vascularity of the defect bed, irradiation damage, infection, or residual tumor, even though the microvascular component of the procedure may be heralded as a success, the likelihood of non-microvascular complications and hence failure to achieve the purpose of the procedure, is higher.

Dimensions

The surgeon must anticipate likely alterations in defect dimensions: for example, after wound contractures have been released, adjacent joints positioned in extremes of functional range of motion, residual pathology, or anticipated die-back of surrounding skin margins are excised. When resurfacing defects on convex surfaces, such as the scalp, heel, or limb, or when myocutaneous flaps are employed and the underlying muscle has to be accommodated, a larger area of skin needs to be included to account for the increased circumference. Skin size can become critically deficient once postoperative swelling occurs. Having to release tight sutures postoperatively from a free flap can lead to non-graftable bed exposure and an embarrassing, surviving, islanded monument to incompetent design and the need for further flap coverage. Especially in lower extremity cases, planning must ensure coverage of the pedicle, which may be farther from the defect. Tension surrounding the pedicle must be minimized to ensure that there is no external pressure. It may be preferable to intentionally accept a second-stage reduction of redundant tissue once swelling has resolved. Additionally, the surgeon should ensure that the chosen flap is of adequate volume to obliterate dead space and not merely be of sufficient area to permit wound closure. In breast reconstruction, the flap size may be deliberately smaller than the opposite side, in anticipation of a secondary reduction on that side.