Effect of Obesity on Flap and Donor-Site Complications in Free Transverse Rectus Abdominis Myocutaneous Flap Breast Reconstruction


   University of Texas M. D. Anderson Cancer Center | April 1999 |

Effect of Obesity on Flap and Donor-Site Complications in Free Transverse Rectus Abdominis Myocutaneous Flap Breast Reconstruction

Commentary by R.J. Allen, M.D.

According to Chang, Wang, Robb, et al., 97% of obese patients in their study who underwent autologous tissue breast reconstruction had a successful outcome. At the same time, compared with normal-weight patients, obese patients also experienced four times the rate of abdominal hernia, which largely may have been preventable. By excising the rectus abdominis muscle, the surgeons removed a crucial structure whose natural function is to retain abdominal contents. Morbidity could have been significantly reduced or eliminated by using a deep inferior epigastric perforator (DIEP) or superficial inferior epigastric artery (SIEA) free fla, in which abdominal fat and skin is removed to reconstruct the breast wile leaving the rectus abdominis muscle intact. In the obese patient, the DIEP or SIEA free flap breast reconstruction would have the added benefit of doubling as a pannulectomy, a well-recognized treatment to improve functional mobility in the morbidity obese. The authors correctly concluded that obesity should not be considered a contraindication to autologous tissue breast reconstruction, but ultimately the best method of breast reconstruction to reduce morbidity and improve function-particularly in the obese-is the DIEP or SIEA flap breast reconstruction.

R.J. Allen, M.D.


Effect of Smoking on Complications in Patients Undergoing Free TRAM Flap Breast Reconstruction

Smoking has long been considered a relative contraindication for autogenous tissue breast reconstruction, due in part to the vasoconstrictive effects of nicotine, tissue hypoxia from carbon monoxide in cigarettes, and blood hypercoagulability caused by increased platelet aggregation. Similar to the results reported by Chang, Reece, Wang, et al., in our series of 343 patients with deep inferior epigastric perforator (DIEP) flap breast reconstruction we found fat necrosis to be more than four times as conunon in smokers as non- smokers and delayed abdominal wound healing to be three times as common in smokers as non-smokers. Like the surgeons at MD Anderson we request patients electing autogenous tissue breast reconstruction to stop smoking at least 3-4 weeks prior to surgery, as after this period the postoperative complication rate among former smokers becomes comparable to that of nonsmokers. Indeed, Chang, Reece, Wang, et al also report a three times higher incidence of abdominal hernia among smokers as compared to non-smokers, and consistent with their hypothesis that this may be due in part to excessive postoperative coughing and increased tension at the abdominal fascial closure, former smokers who have quit at least 4 weeks prior to surgery reduce their incidence of abdominal hernia to a rate almost as low as non-smokers. Yet the baseline rate of abdominal hernia is different among patients who sacrifice their rectus abdominis muscle to undergo a myocutaneous free flap breast reconstruction and those who retain their rectus abdominis muscle to undergo a free perforator flap breast reconstruction. Even considering only the best case scenario, the non-smokers and former smokers in this series still reported more than double the incidence of abdominal hernia as all patients-including smokers and non-smokers-in our series of 551 patients who retained their rectus abdomuns muscle. By preserving the rectus abdominis muscle, the DIEP flap largely avoids the problem of abdominal herniation by allowing the abdominal wall to remain competent. Better still is the superficial inferior epigastric artery (SIEA) free flap, which minimizes donor morbidity even ftuther by making it unnecessary to penetrate the fascial layer. Thus, while we agree that smoking cessation 3-4 weeks prior to surgery is an important therapy to reduce complications in free flap breast reconsftiicfions, ultimately the best way to minimize postoperative complications such as abdominal herniation is via the DIEP or SIEA free flap breast reconstruction.

RJ Allen
CM Chen


Effect of Obesity on Flap and Donor-Site Complications in Free Transverse Rectus Abdominis Myocutaneous Flap Breast Reconstruction

David W. Chang, M.D., Bao-guang Wang, M.D., Ph.D., Geoffrey L. Robb, M.D., Gregory P. Reece, M.D., Michael J. Miller, M.D., Gregory R.D. Evans, M.D., Howard N. Langstein, M.D., and Stehen S. Kroll, M.D.

Houston, Texas

The purpose of this study was to assess the effect of obesity on flap and donor-site complications in patients undergoing free transverse rectus abdominis myocutaneous (TRAM) flap breast reconstruction. All patients undergoing breast reconstruction with free TRAM flaps at our institution from February 1, 1989, through May 31,1998, were reviewed. Patien@s were divided into three groups based on their body mass index: normal (body mass index <25), overweight (bodv mass index 25 to 29),(body mass index >30). Flap and donor-site complications in the three groups were compared.

A total of 936 breast reconstructions with free TRM flaps were performed in 718 patients. There were 442 (61.6 percent) normal-weight. 212 (29.5 percent) over-weight, and 64 (8.9 percent) obese patients. Flap complications occurred in 222 of 936 flaps (23.7 percent). Compared with normal-weight patients, obese patients had a significantly higher rate of overall flap complications (39.1 versus 20.4 percent; p=0.001), total flap loss (3.2 versus 0 percent; p=0.0001), flap seroma (10.9 versus 3.2 percent; p=0.004), and mastectomy flap necrosis (21.9 versus 6.6 percent; p=0.001). Similarly, overweight patients had a significantly higher rate of overall flap complications (27.8 versus 20.4 percent; p=0.033), total flap loss (1.9 versus 0 percent p=0.004), flap hematoma (0 versus 3.2 percent; p=0.007), and mastectomy flap necrosis (15.1 versus 6.6 percent; p=0.001) compared with normal-weight patients. Donor-site complications occurred in 106 of 718 patients (14.9 percent). Compared with normal-weight patients, obese patients had a significantly higher rate of overall donor-site complications (23.4 versus 11.1 percent; p=0.005), infection (4.7 versus 0.5 percent; p=0.016), seroma (9.4 versus 0.9 percent; P<0.001), and hernia (6.3 versus 1.6 percent; p=0.039). Similarly, overweight patients had a significantly higher rate of overall donor-site complications (19.8 versus 11.1 percent; p=0.003), infection (2.4 versus 0.5 percent: p=0.039), bulge (5.2 versus 1.8 percent: p=0.016), and hernia (4.3 versus 1.6 percent: p=0.039) compared with normal-weight patients. There were no significant differences in age distribution, smoking hsitory, or comorbid conditions among the three groups of patients. Obese patients. however, had a significantly higher incidence of preoperative radiotherapy and preoperative radiotherapy and preoperative chemotherapy than did patients in the other two groups. A total of 23.4 percent of obese patients had preoperative radiation therapy compared with 12.3 percent of overweight patients and 12.4 percent of normal-weight patients; 34.4 percent of obese patients had preoperative chemotherapy compared with 24.5 percent of overweight patients and 17.7 percent of normal-weight patients. Multiple logistic regression analysis was used to determine the risk factors for flap and donor-site complications while simultaneously controlling for potential confounding factors, including the incidence of preoperative chemotherapy and radiotherapy.

In summary, obese and overweight patients undergoing breast reconstruction with free TRAM flaps had significantly higher total flap loss. flap hematoma, flap seroma, mastectomy skin flap necrosis, donor-site infection, donor-site seroma, and hernia compared with normal- weight patients. There were no significant differences in the rate of partial flap loss, vessel thrombosis, fat necrosis, abdominal flap necrosis, or umbilical necrosis between any of the groups.

The majority of overweight and even obese patients who undertake breast reconstruction with free TRAM flaps complete the reconstruction successfully. Both such patients and surgeons, however, must clearly understand that the risk of failure and complications is higher than in normal-weight patients. Patients who are morbidly obese are at a high risk of failure and complications and should avoid any type of TRAM flap breast reconsruction. (Plast. Reconstr. Surg. 105: 1640. 2000.)

Obesity is generally considered a contraindication for pedicled transverse rectus abdominis myocutancous (TRAM) flap breast reconstruction. (1,2) It is believed that pedicled TRAM flap breast reconstruction in markedly obese patients is associated with unacceptably high rates of flap and donor-site morbidity (1-4). For obese and other high-risk patients, such as heavy smokers, the free TRAM flap is often advocated for breast reconstruction, (3,5-13)

Use of the free TRAM flap for breast reconstruction was first described by Holmstrom in 1979. (14) With the free TRAM flap, the deep inferior epigastric system is used to maximize the blood flow of the flap. In addition, less donor-site sacrifice is required; less extensive abdominal undermining is needed as well as less sacrifice of abdominal fascia and muscle. The better blood supply and the limited donor-site sacrifice are said to result in lower complication rates than are seen with use of the pedicle TRAM flap in these high-risk patients. (3,9-15)

However, many consider obesity to be a relative contraindication to free TRAM flap reconstruction as well. (3,6-8,10,11) It is believed that the large and heavy abdominal flap stretches and attenuates the musculocutaneous perforators, thus compromising blood supply to the flap. (1) Although the increased surgical risks in obese-patients with other procedures are well documented, the risks of free TRAM flap breast reconstruction in obese patients have never been quantified. (16-21) Whether use of the free TRAM flap is a desirable option for breast reconstruction in obese patients is still unclear.

In this study, we reviewed our experience at the University of Texas M. D. Anderson Cancer Center with free TRAM flap breast reconstruction to determine whether flap and donor-site complications were more common in obese and overweight patients than in normal-weight patients. As a result, we hoped to address the following questions: 'What are the risks of free TRAM flap breast reconstruction in overweight and obese patients? Should we be doing free TRAM flap breast reconstruction in overweight and obese patients?

Patients and Methods

All patients who underwent breast reconstruction with free TRAM flaps at the M. D. Anderson Cancer Center between February 1, 1989, and May 31, 1998, were reviewed. All data reviewed had been collected prospectively and entered into a computerized database. Patients were divided into three groups on the basis of their body mass index [weight (kg)/ height (M)2]: normal (body mass index <25), overweight (body mass index 25 to 29.9), and obese (body mass index >30). Patients were originally divided into five body mass index groups according to the recommendation of the International Obesity Task Force: thin (body mass index <18.5), normal (body mass index 18.5 to 24.9), overweight (body mass index 25.0 to 29.9), obese (body mass index 30.0 to 39.9), and morbidly obese (body mass index > 40.0).(22) Owing to the relatively small number of patients in the categories of thin and morbidly obese, these categories were combined with the normal and obese categories, respectively.

Flap and donor-site complications in the three groups were compared. Flap complications evaluated included partial and total flap loss, vessel thrombosis, flap hematoma, flap infection, flap seroma, TRAM flap fat necrosis, and mastectomy skin flap necrosis. Donor-site complications evaluated included abdominal flap necrosis, umbilical necrosis, hematoma, infection, seroma, bulge, and hernia.

Information on demographic characteristics, smoking history, other comorbid medical conditions, and preoperative radiotherapy and chemotherapy was used to perform multivariate statistical analysis. Comorbid conditions included were diabetes, hypertension, cerebrovascular disease, peripheral vascular disease, coronary artery disease, arrhythmias, chronic obstructive lung disease, and congestive heart failure.

Statistical Analysis

We used descriptive statistics, such as mean, SD, and percentage, to compare patient subgroups. We also compared the characteristics of the patients among subgroups using the chi-square test to identify potential confounding factors. We calculated the incidence of each individual complication and the overall incidence of complications. The incidence of donor-site complications was calculated on the basis of patients, whereas the incidence of flap complications was calculated on the basis of flaps. Multiple logistic regression analysis was used to determine the risk factors for flap and donor-site complications while simultaneously controlling for potential confounding factors. We presented both full model and final model to show the impact of potential confounding factors on the incidence of flap and donor-site complications. Full model included overweight, obesity, preoperative radiotherapy, and preoperative chemotherapy. Final model contained the risk factors for flap and donor-site complications and was selected using the step-wise method. The logistic regression analyses were based on the number of patients for both flap and donor-site complications. A p value of less than 0.05 was considered statistically significant. No correction was made for multiple testing in Tables I through IV. In Tables V and VI, 95 percent confidence interval for odds ratio that did not include 1 was considered statistically significant. The Statistical Analysis System software package (SAS Institute, Inc., Cary, N.C.) was used for all analyses.

Results

During the study period, 936 breast reconstructions with free TRAM flaps were performed in 718 patients; 80.9 percent were immediate and 23.3 percent were bilateral. A total of 442 patients (61.6 percent) were in the normal-weight group, 212 patients (29.5 percent) were in the overweight group, and 64 patients (8.9 percent) were in the obese group (Table 1). There were no significant differences in age distribution, smoking history, or comorbid conditions among the three groups of patients. Obese patients, however, had a significantly higher incidence of preoperative radiotherapy and preoperative chemotherapy than did patients in the other two groups. A total of 23.4 percent of obese patients had preoperative radiation therapy compared with 12.3 percent of overweight patients and 12.4 percent of normal-weight patients. Also, 34.4 percent of obese patients had preoperative chemotherapy compared with 24.5 percent of overweight patients and 17.7 percent of normal-weight patients.

Overall Complication Rates

Flap and donor-site complications are shown in Table II. Flap complications occurred in 222 (23.7 percent) of 936 flaps. The most common flap complication was mastectomy skin flap necrosis (10.3 percent). The rate of total flap loss was 0.9 percent, and the rate of TRAM flap fat necrosis was 5.9 percent.

Donor-site complications occurred in 106 (14.8 percent) of 718 patients. The most common donor-site complication was umbilical necrosis (5.4 percent).

Flap Complications by Subgroups

Flap complications were significantly more common in obese patients and overweight patients than in normal-weight patients (Table III). Compared with normal-weight patients, obese patients had significantly higher rates of overall flap complications (p = 0.001), total flap loss (p = 0.001), flap seroma (p = 0.004), and mastectomy, flap necrosis (p = 0.001). No significant differences were noted in the rates of partial flap loss, vessel thrombosis, hematoma, infection, or fat necrosis.

Compared with normal-weight patients, overweight patients had significantly higher rates of overall flap complications (p = 0.033), total flap loss (p = 0.004), and mastectomy skin flap necrosis (p = 0.001). Normal-weight patients, however, had a significantly higher rate of flap hematoma compared with overweight patients (p = 0.007). No significant differences were noted in the rates of partial flap loss, vessel thrombosis, infection, seroma, or fat necrosis.

Donar-Site Complications by Subgroup

Donor-site complications were significantly more common in obese patients and overweight patients than in normal-weight patients (Table IV). Compared,with normal-weight patients, obese patients had significantly higher rates of overall donor-site complications (p = 0.005), infection (p = 0.016), seroma (p < 0.001), and heri-iia (p = 0.039). No significant differences were noted in the rates of abdominal flap necrosis, umbilical necrosis, hematoma, or abdominal bulging.

Compared with normal-weight patients, overweight patients had significantly higher rates of overall donor-site complications (p = 0.003), infection (p = 0.039), bulge (p = 0.016), and hernia (p = 0.039). No significant differences were noted in the rates of abdominal flap necrosis, umbilical necrosis, hernatoma, or seroma.

Tables V and VI show that obesity and being overweight were significant risk factors for increase in complications after controlling for preoperative radiation and chemotherapy.

Discussion

The increase in surgical risk for obese patients is well known. Postoperative complications, such as wound infections, poor tissue healing, and cardiopulmonary complications, are found more frequently in obese patients.(16-21) Obesity has also been associated with increased morbidity in patients undergoing pedicled TRAM flap breast reconstruction.(1-4) In fact, most consider obesity to be a contraindication for pedicled TRAM flap breast reconstruction. However, the status of obesity as a contraindication for free TRAM flap breast reconstruction has been unclear. Free TRAM flaps offer the advantages of improved blood supply to the flap and reduced abdominal donor-site sacrifice. Associated morbidity might be low enough to perform free TRAM flaps for breast reconstruction in obese patients.

In reviewing our experience, we found that both flap and donor-site complication rates were significantly higher in obese patients undergoing free TRAM flap breast reconstruction than in normal-weight patients undergoing the procedure (Figs. 1 and 2). Obese patients had about twice the flap and donor-site complication rates of normal-weight patients. Over-weight patients also had significantly higher complication rates than normal-weight patients, although the rates were not as high as those in obese patients.

Although obese patients were noted to have a higher incidence of preoperative radiotherapy and preoperative chemotherapy than patients in the other two groups, we do not believe this played a significant role in higher flap-related complications found in obese patients. In our experience, we have not found significantly higher flap-related complications in patients undergoing free TRAM flap breast reconstruction after radiotherapy or chemotherapy. (23,24) In addition, our data were evaluated using multivariate statistical analysis to account for other potential confounding factors, including the incidence of preoperative chemotherapy and radiotherapy.

Flap Loss

Obese and overweight patients had significantly higher rates of total flap loss than normal-weight patients (Fig. 3). Because no significant differences in vessel thrombosis were noted among the three groups, it seems that the higher rates of flap loss in obese and over-weight patients were most likely the result of less successful salvage of ischemic flaps in these patients. Some believe that the large and heavy abdominal flap in obese patients stretches and attenuates the musculocutaneous perforators, thus compromising blood supply to the flap.(1) This may explain why the ischemic flaps are difficult to salvage in obese patients. If the source of the problem is at the perforators and not at the anastomoses, then merely revising the anastomoses would not be sufficient to revive the ischemic flap.

With large TRAM flaps, a careful attention in handling the flap during the elevation and insetting may prevent potential stretching of the perforators by the weight of the heavy flap. One may consider tacking the edge of the fascia to the flap with sutures to minimize accidental attenuation of the perforators during the harvesting of the flap. Also, securing the flap to the chest wall during the insetting, especially at the superior border, may reduce the tension placed on the perforators by the weight of the flap. Postoperatively, use of a brassiere to support the breast may be helpful. However, one must be cautious of the potential compression of the vascular pedicle by the use of brassiere during the early postoperative period.

Fat Necrosis

Fat necrosis is defined as the formation of a small firm area of scar tissue in the periphery of a flap caused by, ischemic necrosis of subcu- taneous fat in the absence of necrosis of overlying flap skin.(25) Consistent with the previous report by the senior author,(25) no significant increase in fat necrosis was noted in either obese or overweight patients. Although obese and overweight patients are at higher risk for flap loss, at 96.8 and 98.1 percent success rate, respectively, free TRAM flaps in these patients are still well vascularized tissue, indicated by relatively low incidence of fat necrosis.

Hematoma, Infection, and Seroma

The incidence of hematoma was not increased in obese or overweight patients. Actually, the flap hematoma rate was significantly lower in obese and overweight patients than in normal-weight patients. Although it is possible that small hematomas under the large flaps may be harder to detect, clinically significant hematomas would have been noted. Perhaps the less robust blood flow relative to the volume of the obese flaps in obese patients led to less likelihood of bleeding from the flaps and thus the lower incidence of hematoma. However, as expected, flap and donor-site seroma rates were significantly higher in obese patients (Figs. 4 and 5). As the sizes of the defect and the flap are usually larger in obese patients, these patients are more susceptible to seroma formation.

We found significantly higher donor-site infection rates in obese and overweight patients than in normal-weight patients (Fig. 6). The increased risk of surgical wound infections for obese patients is well known.(16) We did not, however, find significantly higher flap infection rates in obese and overweight patients than in normal-weight patients. This may be attributed to well-vascularized free TRAM flap, even in obese patients.

Mastectomy Skin Rap Necrosis

Obese and overweight patients had proportionally higher rates of skin flap necrosis, as expected (Fig. 7). Heavier patients tend to have larger breast skin envelopes. In addition, the tension on the mastectomy skin flaps is expected to be greater from the heavy, larger TRAM flaps. Thus, it is not surprising that obese patients are at higher risk of mastectomy skin flap necrosis.

Abdominal Flap Necrosis and Umbilical Necrosis

As previously reported,(3) obese patients did not have a higher incidence of abdominal flap or umbilical necrosis. With free TRAM flaps, less undermining of the abdominal flap is needed, and less sacrifice of rectus fascia is required. Thus, the damage to the vascularity of the abdominal flap and umbilicus is minimized.

Hernia and Abdominal Bulge

We defined an abdominal bulge as any asymetric abdominal bulging.(4) Hernia was defined as dehiscence of the fascial closure. Obese and overweight patients had significantly higher rates of hernia than did normal-weight patients (Fig. 8). In addition, over-weight patients had a higher incidence of abdominal bulging than did normal-weight patients. These findings are consistent with previous reports regarding higher risk in obese patients with abdominal surgery.(16-21) Several factors in obese patients may, lead to increased healing problems of the abdominal fascia. Obese patients often have increased tension at the fascial closure. The increased risk of postoperative pulmonary complications associated with general anesthesia in these patients may further add to tension at the fascia. Furthermore, the tissue quality of the fascia in obese patients is often poor. As, a result, the abdominal fascia may stretch and become thin, leading to an abdominal bulge. Worse yet, the fascial closure may come undone, or it may tear next to the closure, leading to hernia.

Summary

Obese patients had significantly higher flap and donor-site complications than normal-weight patients. Specifically, compared with normal-weight patients, obese patients had more than three times the rate of total flap loss, flap seroma, and mastectomy skin flap necrosis, more than four times the rate of abdominal hernia, and more than nine times the rate of donor-site infection and seroma.

Overweight patients also had significantly higher flap and donor-site complications than normal-weight patients. Specifically, compared with normal-weight patients, overweight patients had approximately twice the rate of total flap loss, mastectomy, skin flap necrosis, abdominal bulge, and hernia and about five times the rate of donor-site infection.

The answer to the question "Is the free TRAM flap an acceptable option for obese patients?" is still not totally clear even after this study. Although the total flap loss rate in the obese group (3.2 percent) was higher than that in the overweight group (1.9 percent) and in the normal-weight group (0.0 percent), well over 90 percent of patients in the obese group had successful outcomes. It is clear that the incidence of failures and complications is higher in obese patients, and in fact there seems to be an almost linear relationship between complications of all kinds and body weight. Nevertheless, most obese patients were pleased by their results and were happy that they had undertaken the surgery.

Given the findings from our study, the decision whether to perform free TRAM flap for breast reconstruction in obese or overweight patients probably should be individualized based on the patient's and the physician's perspective. For those who are willing to accept higher risks of complications, free TRAM flap may be considered an acceptable choice for breast reconstruction, even for obese patients. We believe that for markedly and morbidly obese patients (body mass index >40), TRAM flap breast reconstruction probably should be avoided if possible. For patients who are obese but are less than markedly obese (body mass index equal to or greater than 30 but less than 40), free TRAM flap reconstruction may be considered for those patients in otherwise good health who are well informed of their increased risk of failure and complications. If the reconstruction is a delayed one and the patient is able to reduce her risk by losing weight before the surgery, she should be encouraged to do so. That a patient is overweight (body, mass index 25 to 30) probably should not be considered a contraindication for free TRAM flap breast reconstruction.

David W. Chang, M.D.
Department of Plastic and Reconstructive Surgery
University of Texas M. D. Anderson Cancer Center
1515 Holcombe Boulevard, Box 62
Houston, Texas 77030
dchang@mdaizderson.org




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