Is Diabetes a Contraindication to Lower Extremity Flap Reconstruction? An Analysis of Threatened Lower Extremities in the NSQIP Database (2010-2020).

Background The impact of diabetes on complication rates following free flap (FF), pedicled flap (PF), and amputation (AMP) procedures on the lower extremity (LE) is examined. Methods Patients who underwent LE PF, FF, and AMP procedures were identified from the 2010 to 2020 American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP®) database using Current Procedural Terminology and International Classification of Diseases-9/10 codes, excluding cases for non-LE pathologies. The cohort was divided into diabetics and nondiabetics. Univariate and adjusted multivariable logistic regression analyses were performed. Results Among 38,998 patients undergoing LE procedures, 58% were diabetic. Among diabetics, 95% underwent AMP, 5% underwent PF, and <1% underwent FF. Across all procedure types, noninsulin-dependent (NIDDM) and insulin-dependent diabetes mellitus (IDDM) were associated with significantly greater all-cause complication rates compared with absence of diabetes, and IDDM was generally higher risk than NIDDM. Among diabetics, complication rates were not significantly different across procedure types (IDDM: p = 0.5969; NIDDM: p = 0.1902). On adjusted subgroup analysis by diabetic status, flap procedures were not associated with higher odds of complications compared with amputation for IDDM and NIDDM patients. Length of stay > 30 days was statistically associated with IDDM, particularly those undergoing FF (AMP: 5%, PF: 7%, FF: 14%, p = 0.0004). Conclusion Our study highlights the importance of preoperative diabetic optimization prior to LE procedures. For diabetic patients, there were few significant differences in complication rates across procedure type, suggesting that diabetic patients are not at higher risk of complications when attempting limb salvage instead of amputation.

Patient-Reported Outcomes on Subjective Nipple Sensation After Double-Incision and Periareolar Mastectomy for Chest Masculinization: Subjective Nipple Sensation After Chest Masculinization.

ABSTRACT: We evaluated patient-reported outcomes to assess for patient and procedural factors associated with postchest masculinization subjective nipple sensation. Patients who underwent double-incision or periareolar mastectomies for chest masculinization by a single senior surgeon (2015-2019) were surveyed at 2 time points regarding postoperative nipple sensation and satisfaction, including patient-reported outcomes using BODY-Q modules (Q-Portfolio.org). Demographic, operative, and postoperative variables were obtained from medical records. Patients were stratified according to survey responses. Univariate and multivariate analyses were performed.Response rate was 42% for survey 1 and 22% for survey 2. Of the 151 survey 1 responders, 138 (91.4%) received double-incision mastectomies and 13 (8.6%) received periareolar mastectomies. Among Survey 1 responders, 84.6% periareolar patients and 69.6% double-incision patients reported "completely" or "a little" nipple sensation preservation, and the difference trended toward significance (P = 0.0719). There was a stepwise increase in proportion of patients reporting sensation with greater recovery time until response to survey 1. Obesity (P = 0.0080) and greater tissue removed (P = 0.0247) were significantly associated with decreased nipple sensation. Nipple satisfaction scores were significantly higher for patients reporting improved nipple sensation (P = 0.0235). Responders to survey 2 who reported greater satisfaction with nipple sensation were significantly more likely to report preserved sensitivity to light touch (P = 0.0277), pressure (P = 0.0046), and temperature (P = 0.0031). Preserved erogenous sensation was also significantly associated with greater satisfaction (P = 0.0018).In conclusion, we found that nipple sensation may be associated with postoperative nipple satisfaction. Operative techniques to optimize nipple sensation preservation may improve this population's postoperative satisfaction.

Impact of sternal notch-to-nipple distance and resection weight asymmetry on complication rates and patient reported outcomes in reduction mammaplasty.

While there are numerous predictive models for estimating resection weight, their accuracy may not be strong. Through institutional data of patients who received reduction mammaplasty, this study demonstrates that preoperative sternal notch-to-nipple distance is not an optimal predictive factor for differences in final resection weight, complication rates, and patient reported outcomes. Our results showed that there is a weak correlation between preoperative sternal notch to nipple asymmetry and final resection weight asymmetry. Additionally, significant breast asymmetry is not tied to an increase in complication rates or poorer patient reported outcomes. There is an indication to reconsider the use of such absolute measures for determining who may benefit from reduction mammaplasty.

Does Frailty Predict Outcomes in Patients Undergoing Free or Pedicled Flap Procedures for Lower Extremity Limb Salvage? An Analysis of the American College of Surgeons National Surgical Quality Improvement Program Database.

BACKGROUND: Older and frailer patients are increasingly undergoing free or pedicled tissue transfer for lower extremity (LE) limb salvage. This novel study examines the impact of frailty on postoperative outcomes in LE limb salvage patients undergoing free or pedicled tissue transfer. METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database (2010-2020) was queried for free and pedicled tissue transfer to the LE based on Current Procedural Terminology and the International Classification of Diseases9/10 codes. Demographic and clinical variables were extracted. The five-factor modified frailty index (mFI-5) was calculated using functional status, diabetes, chronic obstructive pulmonary disease, congestive heart failure, and hypertension. Patients were stratified by mFI-5 score: no frailty (0), intermediate frailty (1), and high frailty (2 + ). Univariate analysis and multivariate logistic regression were performed. RESULTS: In total, 5,196 patients underwent free or pedicled tissue transfer for LE limb salvage. A majority were intermediate (n = 1,977) or high (n = 1,466) frailty. High frailty patients had greater rates of comorbidities-including those not in the mFI-5 score. Higher frailty was associated with more systemic and all-cause complications. On multivariate analysis, the mFI-5 score remained the best predictor of all-cause complications-with high frailty associated with 1.74 increased adjusted odds when compared with no frailty (95% confidence interval: 1.47-2.05). CONCLUSION: While flap type, age, and diagnosis were independent predictors of outcomes in LE flap reconstruction, frailty (mFI-5) was the strongest predictor on adjusted analysis. This study validates the mFI-5 score for preoperative risk assessment for flap procedures in LE limb salvage. These results highlight the likely importance of prehabilitation and medical optimization prior to limb salvage.

Pedicled Flaps for High-Risk Open Vascular Procedures of the Lower Extremity: An Analysis of The National Surgical Quality Improvement Project Database.

BACKGROUND: Use of pedicled flaps in vascular procedures is associated with decreased infection and wound breakdown. We evaluated the risk profile and postoperative complications associated with lower extremity open vascular procedures with and without pedicled flaps. METHODS: The American College of Surgeons National Surgical Quality Improvement Program database (2010-2020) was queried for Current Procedural Terminology codes representing lower extremity open vascular procedures, including trunk and lower extremity pedicled flaps. Flap patients were compared with a randomized control group without flaps (1:3 cases to controls). Univariate and multivariate analyses were performed. RESULTS: We identified 132,934 adults who underwent lower extremity open vascular procedures. Concurrent pedicled flaps were rare (0.7%), and patients undergoing bypass procedures were more likely to receive a flap than nonbypass patients (69 vs. 64%, p < 0.0001). Flap patients had greater comorbidities. On univariate analysis, flap patients were more likely to experience wound (p = 0.0026), mild systemic (p < 0.0001), severe systemic (p = 0.0452), and all-cause complications (p < 0.0001). After adjusting for factors clinically suspected to be associated with increased risk (gender, body mass index, procedure type, American Society of Anesthesiologists classification, functional status, diabetes, smoking, and albumin < 3.5 mg/dL), wound (p = 0.096) and severe systemic complications (p = 0.0719) were no longer significantly associated with flap patients. CONCLUSION: Lower extremity vascular procedures are associated with a high risk of complications. Use of pedicled flaps remains uncommon and more often performed in patients with greater comorbid disease. However, after risk adjustment, use of a pedicled flap in high-risk patients may be associated with lower than expected wound and severe systemic complications.

Sternal bone anatomy on preoperative imaging as an independent predictor of deep sternal dehiscence following median sternotomy.

Complications following median sternotomy are associated with morbidity, mortality, and major healthcare costs. With plastic surgeons being increasingly consulted to close complex sternotomy wounds, a more accurate risk stratification tool for this comorbid patient population is warranted. This study examines the association of preoperative radiologic sternal measurements and deep sternal dehiscence, comparing this with other known clinical risk factors. A decreased manubrium sternal thickness relative to body weight (<0.13 mm/kg) and an absolute inferior sternal width ≤13.8 mm had a significant association with the development of deep sternal dehiscence, even with adjustment for known clinical risk factors. With such measurements assisting in further risk stratification, the opportunity to improve risk assessment holds value for plastic and reconstructive surgeons who are consulted to close extensive sternotomy wounds.

Novel use of interosseous absorbable mattress sutures for secondary sternal fixation: A case series.

There is currently no consensus on the treatment of median sternotomy patients presenting secondarily with deep sternal wound infection or symptomatic sternal nonunion. We have developed a novel approach to sternal bone fixation when concerns for open wounds or microbial colonization preclude the use of permanent hardware placement: (1) sternal closure with absorbable interosseous monocortical horizontal mattress sutures followed by (2) multilayered soft tissue closure with pectoralis major advancement or turnover flaps. Benefits of this technique include: closure of retrosternal dead-space, tension offloading of the soft tissue closure, repair of transverse sternal fractures, and preservation of internal mammary artery (IMA) perforators for potential pectoralis turnover flaps. In our early experience, this technique has been successful at promoting functional sternal union - even in secondary closure of high-risk patients contraindicated for permanent hardware placement.

The Effect of Preoperative Diagnosis of Depression and/or Anxiety on Patient-Reported Outcomes Following Chest Wall Masculinization Surgery.

BACKGROUND: Individuals with gender dysphoria have disproportionately high rates of depression and anxiety compared to the cisgender population. Although the benefits of gender affirmation surgery have been well documented, it is unclear whether depression and anxiety affect postoperative patient-reported outcomes (PRO). OBJECTIVES: The authors evaluated the impact of preoperative anxiety or depression on clinical and PRO in patients undergoing chest masculinization surgery. METHODS: Patients who underwent chest masculinization surgery within a 5-year period were reviewed. Demographics and clinical variables were abstracted from medical records. PRO of chest, nipple, and scar satisfaction were obtained postoperatively with the BODY-Q. Groups were stratified by preoperative anxiety, preoperative depression, both, or no history of mental health diagnosis. Univariate and multivariate analyses were performed. RESULTS: Of 135 patients with complete survey responses, 10.4% had anxiety, 11.9% depression, 20.7% both diagnoses, and 57.0% no diagnosis. Clinical data and outcomes were similar. Patients with preoperative depression correlated with lower satisfaction scores for scar appearance (P = .006) and were significantly more likely to report feelings of depression postoperatively (P = .04). There were no significant differences in chest or nipple satisfaction among groups. CONCLUSIONS: Although anxiety and depression are prevalent in gender minorities, we found no association with postoperative clinical outcomes. Patients with preoperative depression were more likely to report lower satisfaction with scar appearance and feelings of depression postoperatively. However, there were no differences in chest or nipple satisfaction. These results highlight the importance of perioperative mental health counseling but also suggest that patients can be satisfied with their results despite a coexisting mental health diagnosis.

The use of abdominal wall tissue expansion prior to herniorrhaphy in massive ventral hernia defects.

BACKGROUND: Massive ventral hernias pose a challenging reconstructive problem. In comparison to bridging mesh repair, the primary fascial repair is associated with significantly reduced rates of hernia recurrence. This study will review our experience with massive ventral hernia repairs using tissue expansion and anterior component separation as well as present the largest case series to date. METHODS: A retrospective review was conducted of 61 patients who underwent abdominal wall tissue expansion prior to herniorrhaphy at a single institution between 2011 and 2017. Demographics, perioperative co-variates, and outcomes were recorded. Univariate and subgroup analysis was performed. Kaplan-Meier survival analysis was used to assess the time to recurrence. RESULTS: Sixty-one patients underwent abdominal wall expansion via tissue expanders (TE). Of these, 56 subsequently underwent staged anterior component separation for attempted closure of large ventral hernia. Major complications of TE placement included TE replacement (4,6.6%), TE leak (2,3.3%), and unplanned readmission (3,4.9%). Higher BMI groups were significantly associated with comorbid hypertension (BMI<30 kg/m2, 22.7%; BMI 30-35 kg/m2, 68.7%; BMI>35 kg/m2, 64.7%; P = 0.004). 15 patients (32.6%) had hernia recurrence and 21 patients (34.4%) still required bridging mesh during herniorrhaphy after tissue expansion. CONCLUSION: The use of tissue expansion prior to herniorrhaphy can be effective in achieving durable closure for most massive abdominal wall defects - especially those associated with musculofascial, soft tissue, or skin deficiencies. In this proof-of-concept analysis, we found that the efficacy and safety profile of this technique compares favorably to other methods for massive hernia repair in the literature.

Outpatient Prosthetic-Based Reconstruction during COVID-19 Pandemic Possible in Selected Patients without Increased Complications.

BACKGROUND: Following the reopening of elective surgery, the authors' division transitioned from inpatient admission to same-day discharge for immediate prosthetic breast reconstruction in an effort to decrease the hospital's clinical burden and minimize potential coronavirus disease of 2019 exposure. This study aims to compare complication rates following this acute transition for patients who had inpatient and outpatient mastectomy with immediate alloplastic reconstruction. METHODS: A retrospective chart review was performed on patients who underwent mastectomy with immediate prosthetic reconstruction. The outcome of interest was 30-day morbidity. Descriptive statistics were compared for patients with outpatient and inpatient operations. Odds ratios were calculated to determine whether any preoperative factors increased odds of 30-day complications. RESULTS: A total of 115 patients were included in this study. Twenty-six patients had outpatient surgery and 89 stayed inpatient postoperatively. Same-day discharge did not significantly impact the odds of having one or more 30-day complications (OR, 0.275; 95% CI, 0.047 to 1.618; P = 0.153). Patients with complications had significantly longer median operating times [5.0 hours (interquartile range, 4.0 to 6.0 hours) versus 4.0 hours (interquartile range, 3.0 to 5.0 hours; P = 0.05), and there was a statistically significant association between length of surgery and odds of complication (OR, 1.596; 95% CI, 1.039 to 2.451; P = 0.033). Age was independently associated with increased risk of 30-day complication (OR, 1.062; 95% CI, 1.010 to 1.117; P = 0.020). CONCLUSION: The authors' findings support a continuation of same-day discharge strategy, which could decrease costs for patients and hospitals without increasing complications. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Development of a risk score to predict occurrence of deep sternal dehiscence requiring operative debridement.

OBJECTIVE: Severe deep sternal wound (DSW) complications after cardiac surgery are a source of cost, morbidity, and mortality. Our objective was to develop and validate a clinical risk score for predicting risk of DSW requiring operative bone debridement, the most severe form of sternal dehiscence. METHODS: A retrospective review was conducted of patients who underwent open cardiac surgery at a single institution between October 2007 and March 2019. Primary outcome was DSW requiring sternal bone debridement. Potential risk factors were screened using Least Absolute Shrinkage and Selection Operator (LASSO) and significant covariates were included in a logistic regression prediction model. Interval validation was performed using 10-fold cross-validation. A novel sternal wound dehiscence risk score was derived from the relative parameterization estimates. RESULTS: One hundred thirty-four of 8403 patients (1.6%) were identified as having a DSW. Female sex (odds ratio [OR], 2.75; 95% CI, 2.58-2.93), body mass index (OR, 1.0946; 95% CI, 1.09-1.09), percent glycated hemoglobin (OR, 1.31; 95% CI, 1.28-1.33), peripheral vascular disease (OR, 2.38; 95% CI, 2.2005-2.5752), smoking (OR, 1.66; 95% CI, 1.53-1.79) and elevated creatinine level (OR, 1.20; 95% CI, 1.18-1.22) were independent predictors of DSW. Patients were categorized as minimal risk (0%-1%), low risk (2%-3%), intermediate risk (4%-7%), and high risk (9%-64.0%) on the basis of risk score. CONCLUSIONS: This risk stratification model for DSW requiring operative debridement might provide individualized estimates of risk, and guide counseling and potential risk mitigation strategies.

An Algorithmic Approach to the Surgical Management of Sternal Dehiscence: A Single-Center Experience.

BACKGROUND: Deep sternal wound complications following sternotomy represent a complex challenge. Management can involve debridement, flap reconstruction, and rigid sternal fixation (RSF). We present our 11-year experience in the surgical treatment of deep sternal wound dehiscence using a standardized treatment algorithm. METHODS: A retrospective review was conducted of all 134 cardiac patients who required operative debridement after median sternotomy at a single institution between October 2007 and March 2019. Demographics, perioperative covariates, and outcomes were recorded. Univariate and subgroup analyses were performed. RESULTS: One-hundred twelve patients (83.5%) with a deep sternal dehiscence underwent flap closure and 56 (50%) RSF. Of the patients who underwent flap closure, 87.5% received pectoralis advancement flaps. A 30-day mortality following reconstruction was 3.9%. Median length of stay after initial debridement was 8 days (interquartile range: 5-15). Of patients with flaps, 54 (48%) required multiple debridements prior to closure, and 30 (27%) underwent reoperation after flap closure. Patients who needed only a single debridement were significantly less likely to have a complication requiring reoperation (N = 10/58 vs. 20/54, 17 vs. 37%, p = 0.02), undergo a second flap (N = 6/58 vs. 17/54, 10 vs. 32%, p < 0.001), or, if plated, require removal of sternal plates (N = 6/34 vs. 11/22, 18 vs. 50%, p = 0.02). CONCLUSION: Although sternal dehiscence remains a complex challenge, an aggressive treatment algorithm, including debridement, flap closure, and consideration of RSF, can achieve good long-term outcomes. In low-risk patients, RSF does not appear to increase the likelihood of reoperation. We hypothesize that earlier surgical intervention, before the development of systemic symptoms, may be associated with improved outcomes.

Technique of Abdominal Wall Tissue Expansion for the Treatment of Massive Complicated Ventral Hernias.

Abdominal wall tissue expansion is a unique technique that seeks to augment and expand both the fascial and subcutaneous tissues/skin layers to achieve durable closure of otherwise challenging ventral hernias. In addition to allowing primary fascial closure in a majority of cases, this technique enables reduced tension on the closure, potentially decreasing the recurrence rate. This article describes the senior author's surgical technique for abdominal wall tissue expansion in massive complicated ventral hernias. The plastic surgeon is at a unique advantage to assist with the repair of massive complicated ventral hernias given their comfort with complex tissue handling and expandable devices. This specialized technique thus provides an opportunity for plastic surgeons to serve as expert co-surgeons with general surgery colleagues to help achieve superior outcomes in patients with these challenging hernias.

Reconstruction of the Upper Extremity High-Voltage Electrical Injury: A Pediatric Burn Hospital's 13-Year Experience.

High-voltage electrical injury is a rare yet destructive class of burn injury that persists as a serious public health issue. High-voltage exposure is commonly associated with complex wounds to the upper extremities, which can be a significant challenge for burn and plastic surgeons to reconstruct. This intensive and multistage reconstructive process is especially difficult in the growing child. Maximizing upper extremity function is a top priority, as it can have a significant impact on a patient's quality of life. Therefore, the purpose of this retrospective review was to describe lessons learned during a 13-year experience at a specialized pediatric burn hospital with reconstruction of the upper extremity after severe high-voltage injury in 37 children. We found that adherence to the following principles can help promote meaningful functional recovery. These include 1) frequent assessment during early acute care for the evolving need of decompression or amputation; 2) serial surgical debridement that follows a tissue-sparing technique; 3) wound closure by skin grafting or use of flaps (particularly groin or abdominal pedicled flaps) when deep musculoskeletal structures are involved; 4) early multidisciplinary intervention for contracture prevention and management, including physical and occupational therapy, splinting, and fixation; 5) reconstructive care that focuses on the simplest possible techniques to repair chronic skin defects such as laser therapy, local tissue rearrangements, and skin grafting; 6) complex reconstruction to address deeper tissue contractures or tendon and peripheral nerve deficits; and 7) amputation with preservation of growth plates, tissue transfer, and long-term prosthetic management when limb salvage is unlikely.

Predictors of index admission mortality and morbidity in contemporary esophageal atresia patients.

BACKGROUND/PURPOSE: The Spitz classification for esophageal atresia with/without tracheoesophageal fistula (EA/TEF) predicts mortality. This study evaluates the contemporary relevance of the Spitz classification and investigates predictors of morbidity. METHODS: EA/TEF patients born between 1995 and 2018 at two centers were retrospectively reviewed. Clinical variables including sex, prenatal diagnosis, birth weight, prematurity, major congenital heart disease (MCHD), and pre-operative mechanical ventilation (POMV) were collected. Index admission composite morbidity was considered positive if: length-of-stay >90th percentile (139 days), ventilation days >90th percentile (24 days), and/or gastrostomy was used for long-term feeding. Multivariable regression determined predictors of index admission mortality and composite morbidity. A composite morbidity predictive algorithm was created. ROC curves evaluated model discrimination. RESULTS: Of 253 patients, 13 (5.1%) experienced index admission mortality. Of the patients not suffering mortality, 74 (31.6%) experienced composite morbidity. Only MCHD predicted mortality (p = 0.001); birth weight did not (p = 0.173). There was no difference between the Spitz classification and MCHD alone in predicting mortality risk (p = 0.198); both demonstrated very good discrimination. Prenatal diagnosis, POMV, prematurity, and male sex predicted composite morbidity risk (p < 0.001; p = 0.008; p = 0.009; p = 0.05). An algorithm incorporating these predictors demonstrated good discrimination (AUC = 0.784; 95% CI: 0.724, 0.844). CONCLUSIONS: The Spitz classification maintains contemporary relevance for mortality risk, though birth weight can be de-emphasized. A new morbidity risk algorithm is proposed for early postnatal counseling. TYPE OF STUDY: Prognosis study. LEVEL OF EVIDENCE: Level IV.

Long term mortality in critically ill burn survivors.

INTRODUCTION: Little is known about long term survival risk factors in critically ill burn patients who survive hospitalization. We hypothesized that patients with major burns who survive hospitalization would have favorable long term outcomes. METHODS: We performed a two center observational cohort study in 365 critically ill adult burn patients who survived to hospital discharge. The exposure of interest was major burn defined a priori as >20% total body surface area burned [TBSA]. The modified Baux score was determined by age + %TBSA+ 17(inhalational injury). The primary outcome was all-cause 5year mortality based on the US Social Security Administration Death Master File. Adjusted associations were estimated through fitting of multivariable logistic regression models. Our final model included adjustment for inhalational injury, presence of 3rd degree burn, gender and the acute organ failure score, a validated ICU risk-prediction score derived from age, ethnicity, surgery vs. medical patient type, comorbidity, sepsis and acute organ failure covariates. Time-to-event analysis was performed using Cox proportional hazard regression. RESULTS: Of the cohort patients studied, 76% were male, 29% were non white, 14% were over 65, 32% had TBSA >20%, and 45% had inhalational injury. The mean age was 45, 92% had 2nd degree burns, 60% had 3rd degree burns, 21% received vasopressors, and 26% had sepsis. The mean TBSA was 20.1%. The mean modified Baux score was 72.8. Post hospital discharge 5year mortality rate was 9.0%. The 30day hospital readmission rate was 4%. Patients with major burns were significantly younger (41 vs. 47 years) had a significantly higher modified Baux score (89 vs. 62), and had significantly higher comorbidity, acute organ failure, inhalational injury and sepsis (all P<0.05). There were no differences in gender and the acute organ failure score between major and non-major burns. In the multivariable logistic regression model, major burn was associated with a 3 fold decreased odds of 5year post-discharge mortality compared to patients with TBSA<20% [OR=0.29 (95%CI 0.11-0.78; P=0.014)]. The adjusted model showed good discrimination [AUC 0.81 (95%CI 0.74-0.89)] and calibration (Hosmer-Lemeshow χ2 P=0.67). Cox proportional hazard multivariable regression modeling, adjusting for inhalational injury, presence of 3rd degree burn, gender and the acute organ failure score, showed that major burn was predictive of lower mortality following hospital admission [HR=0.34 (95% CI 0.15-0.76; P=0.009)]. The modified Baux score was not predictive for mortality following hospital discharge [OR 5year post-discharge mortality=1.00 (95%CI 0.99-1.02; P=0.74); HR for post-discharge mortality=1.00 (95% CI 0.99-1.02; P=0.55)]. CONCLUSIONS: Critically ill patients with major burns who survive to hospital discharge have decreased 5year mortality compared to those with less severe burns. ICU Burn unit patients who survive to hospital discharge are younger with less comorbidities. The observed relationship is likely due to the relatively higher physiological reserve present in those who survive a Burn ICU course which may provide for a survival advantage during recovery after major burn.