The Impact of Operative Time on Complications After Plastic Surgery: A Multivariate Regression Analysis of 1753 Cases

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1 528503AESXXX / X Aesthetic Surgery JournalHardy et al research-article2014 Research The Impact of Operative Time on Complications After Plastic Surgery: A Multivariate Regression Analysis of 1753 Cases Aesthetic Surgery Journal 2014, Vol. 34(4) The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journalspermissions.nav DOI: / X Krista L. Hardy, BS; Kathryn E. Davis, PhD; Ryan S. Constantine, BS; Mo Chen, PhD; Rachel Hein, BS; James L. Jewell, BS; Karunakar Dirisala, MS; Jerzy Lysikowski, PhD; Gary Reed, MD; and Jeffrey M. Kenkel, MD Abstract Background: Little evidence within plastic surgery literature supports the precept that longer operative times lead to greater morbidity. Objective: The authors investigate surgery duration as a determinant of morbidity, with the goal of defining a clinically relevant time for increased risk. Methods: A retrospective chart review was conducted of patients who underwent a broad range of complex plastic surgical procedures (n = 1801 procedures) at UT Southwestern Medical Center in Dallas, Texas, from January 1, 2008 to January 31, Adjusting for possible confounders, multivariate logistic regression assessed surgery duration as an independent predictor of morbidity. To define a cutoff for increased risk, incidence of complications was compared among quintiles of surgery duration. Stratification by type of surgery controlled for procedural complexity. Results: A total of 1753 cases were included in multivariate analyses with an overall complication rate of 27.8%. Most operations were combined (75.8%), averaging 4.9 concurrent procedures. Each hour increase in surgery duration was associated with a 21% rise in odds of morbidity (P <.0001). Compared with the first quintile of operative time (<2.0 hours), there was no change in complications until after 3.1 hours of surgery (odds ratio, 1.6; P =.017), with progressively greater odds increases of 3.1 times after 4.5 hours (P <.0001) and 4.7 times after 6.8 hours (P <.0001). When stratified by type of surgery, longer operations continued to be associated with greater morbidity. Conclusions: Surgery duration is an independent predictor of complications, with a significantly increased risk above 3 hours. Although procedural complexity undoubtedly affects morbidity, operative time should factor into surgical decision making. Level of Evidence: 3 Keywords research, operative time, surgery duration, postoperative complications, wound complications, morbidity Accepted for publication September 19, The impact of operative time on morbidity has long been a topic of interest, although few studies have specifically addressed this question. The potential risks of prolonged operations are especially pertinent to plastic surgeons, who generally perform lengthy surgeries and often combine procedures to improve both aesthetics and efficiency. Historically, surgery duration has been positively associated with From the UT Southwestern Medical Center, Dallas, Texas. Corresponding Author: Dr Jeffrey M. Kenkel, Department of Plastic Surgery, UT Southwestern Medical Center, 5373 Harry Hines Blvd, Dallas, TX , USA. jeffrey.kenkel@utsouthwestern.edu

2 Hardy et al 615 Table 1. Pertinent Retrospective Data Collected Parameters Recorded Operative time Operation performed Lipectomy, pedicle flap, free flap, SMAS flap rhytidectomy, TE breast reconstruction, autologous breast reconstruction, other breast surgery Baseline patient characteristics Age, sex, BMI, smoking status, other medical and surgical history Comorbidities Diabetes, hypertension, cardiovascular disease, renal comorbidity, COPD Postoperative complications Overall complication, infection, erythema, dehiscence, necrosis, seroma, hematoma, delayed wound healing, flap failure, VTE BMI, body mass index; COPD, chronic obstructive pulmonary disease; SMAS, superficial musculoaponeurotic system; TE, tissue expander; VTE, venous thromboembolism. incidence of wound infection. 1-4 However, despite operative time being commonly accepted as a risk factor for morbidity, the literature regarding its influence on other postoperative complications is either scarce or inconclusive. 5 Two recent large-scale, multicenter studies on breast reconstruction reported increased odds of developing postoperative complications for longer procedures. 6,7 (Odds are the probability of an event occurring divided by the probability of it not occurring.) Still, the scope of these studies is limited; whether the findings can be generalized to other types of plastic surgery remains to be seen. Moreover, these studies made no attempt to define a relevant time beyond which surgery duration significantly influences morbidity. Convention maintains that 6 hours is the critical period, despite lack of evidence supporting this tenet. Indeed, previous studies have focused on operations lasting longer than 6 hours without investigating whether surgery duration has an impact at shorter lengths of time. 8,9 With the goal of better defining the effect of operative duration at different time periods, we conducted a retrospective chart review on a diverse range of plastic surgery procedures. Methods Study Design Institutional review board approval was obtained to conduct a retrospective chart review of 1801 complex plastic surgery procedures performed at UT Southwestern Medical Center (Dallas, Texas) from January 1, 2008, to January 31, Cases were selected based on Current Procedural Terminology (CPT) codes to reflect a broad range of procedures with typically long operative times, including many combined surgeries. Only these CPT codes were followed. Relevant information was collected from patient charts and hospital records, deidentified, and documented in a Microsoft Excel workbook (Microsoft, Redmond, Washington) (Table 1). Patients with multiple encounters were entered on a per-encounter basis. Initial selection was determined by CPT codes, by which the types of surgical procedure also were categorized. All cases with a certain CPT code were included in the corresponding group, regardless of whether multiple procedures were performed. No separate categories were created for surgeries that included CPT codes not included for initial selection. Operations that fell into more than 1 category were counted for each applicable group. For cases in which CPT information was incomplete, grouping was determined by the CPT codes available. Of the 1801 cases reviewed, 1783 (99.0%) had complete operative time and morbidity data; all others were excluded from the analyses. Operative duration was defined as the time between the first incision and final closure. Incidence of morbidity was based on data from follow-up appointments within 1 month after the operation. Surgeries in the other breast surgery group consisted of revision breast reconstruction procedures, as well as delayed breast implant insertion following mastopexy or in reconstruction. The superficial musculoaponeurotic system (SMAS) flap cases were combined with additional procedures, most commonly blepharoplasty, fat injection, and neck and brow lifts. Obesity was defined as a body mass index (BMI) greater than or equal to 30 kg/m 2. Active smokers were patients who smoked within the year prior to surgery. Statistical Analyses Patient demographics were summarized as mean and standard deviation (SD) for continuous variables and as a percentage for categorical variables. Distribution of operative duration was represented by the range and times at 25th, 50th, and 75th percentiles for each surgery type. All surgeries were then further grouped into either those with no complications or those with complications. Overall complications included infection, dehiscence, erythema, necrosis, seroma, hematoma, delayed wound healing, flap failure, and venous thromboembolism (VTE; Table 1). Univariate analyses compared risk factors, including baseline patient characteristics

3 616 Aesthetic Surgery Journal 34(4) and comorbidities commonly associated with relevant postoperative complications. 10 The Fisher exact test and unpaired Student t test calculated categorical and continuous variables, respectively; those with P <.2 were included in multivariate logistic regression models. Cases without complete data for all included variables were omitted. Multivariate regression was applied for all subsequent analyses to adjust for possible confounders of operative time. Independent risk factors for overall surgery-related morbidity were identified, and corresponding adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated. To detect a critical time associated with increased risk, the incidence of overall complications was compared among quintiles of surgery duration. Once a cutoff was identified, cases with operative times above the cutoff were compared with those below it. Incidences of each complication type for all operations were first independently assessed. To determine the effect of procedural complexity, cases were then stratified by surgery type, and overall morbidity was compared via the previously defined cutoff. For groups of long surgeries with fewer than 10 operations under the cutoff, comparisons were made between surgeries shorter or longer than the 80th percentile of surgery duration. Univariate analyses were conducted with GraphPad Prism 6.00 (GraphPad, San Diego, California), while logistic regressions were carried out with SAS 9.3 (SAS Institute, Cary, North Carolina). All statistical tests were 2-sided, with significance defined as P <.05. Results Patient Demographics and Complication Profile Patient demographics were reported on a per-encounter basis (Table 2). Average patient age was 49.6 years (range, years). Mean BMI was 28.3 kg/m 2 (range, kg/m 2 ). Most patients were women (79.8%, n=1423); 10.3% were active smokers (n=183), 13.1% diabetic (n=234), and 32.1% hypertensive (n=572). Procedures included 548 lipectomies (30.7%), 497 pedicle flaps (27.9%), 77 free flaps (4.3%), 37 SMAS rhytidectomies (2.1%), 216 autologous breast reconstructions (12.1%), 183 tissue expander breast reconstructions (10.3%), and 228 other breast surgeries (12.8%). Most operations were combined (75.8%), averaging 4.9 concurrent procedures. Table 2 shows both the overall complication rate and incidence of each complication type. Overall Morbidity and Operative Time Distribution Surgery duration and overall complication rate were analyzed for each procedure type (Table 3). Operations lasted Table 2. Patient Demographics and Complication Profile Parameter Assessed Value n 1783 Age, y a 49.6 ± 13.5 BMI, kg/m 2a 28.3 ± 7.2 Female, % 79.8 Active smokers, % 10.3 Diabetes, % 13.1 Hypertension, % 32.1 Combined procedure, % 75.8 Postoperative complications, % Overall 27.8 Infection 9.0 Dehiscence 5.4 Erythema 6.7 Necrosis 4.9 Seroma 6.8 Hematoma 2.4 Delayed wound healing 3.4 Venous thromboembolism 1.7 BMI, body mass index. a Continuous variables are represented by mean ± SD. anywhere from 0.18 to hours, with a median time of 3.80 hours. Distribution of operative time differed among various types of procedures; autologous breast reconstructions were the longest (median time = 8.77 hours), while other breast surgeries were the shortest (median time = 2.38 hours). For the remaining surgeries, median durations were 3.07 hours for lipectomy, 3.48 hours for pedicle flap, 8.35 hours for free flap, 6.70 hours for SMAS flap rhytidectomy, and 5.08 hours for tissue expander (TE) breast reconstruction. In general, longer surgeries corresponded with greater morbidity. Autologous breast reconstruction and free flap procedures were the longest sharing similar operative times and congruently reflected the greatest overall postoperative complication rates of 47.7% (n = 103) and 48.1% (n = 37), respectively. Following this trend, complication rates of other procedures from shortest to longest were as follows: 12.7% (n = 29) for other breast surgery, 19.0% (n = 104) for lipectomy, and 32.0% (n = 159) for pedicle flap. The most obvious exception to this pattern was the SMAS facelift group, characterized by relatively long operative times yet low morbidity (13.5%, n = 5).

4 Hardy et al 617 Table 3. Overall Complication Rate and Operative Time Distribution by Procedure Surgical Times by Percentile Surgery Type n No. (%) of Complications Ranges of Surgical Time, h 25th 50th 75th All surgeries (27.8) Lipectomy (19.0) Pedicle flap (32.0) Free flap (48.1) SMAS flap rhytidectomy 37 5 (13.5) Autologous breast reconstruction (47.7) TE breast reconstruction (32.2) Other breast surgery (12.7) SMAS, superficial musculoaponeurotic system; TE, tissue expander. Table 4. Risk Factors for Surgeries With Complications vs Surgeries Without Complications Variable No Complication Complication P Value n Operative time, mean ± SD, h a 4.1 ± ± 3.7 <.0001 No. of prior surgeries, mean ± SD 4.9 ± ± No. of concurrent surgeries, mean ± SD 2.4 ± ± Age >50 y 646 (50.2) 275 (55.4).050 BMI 30 kg/m (29.7) 191 (38.8) <.001 Male 244 (19.0) 115 (23.2).048 Active smoker 129 (10.0) 54 (10.9).60 Diabetes 151 (11.7) 83 (16.7).0061 Hypertension 389 (30.2) 183 (36.9).0078 Cardiovascular disease 281 (21.8) 122 (24.6).23 Renal comorbidity 93 (7.2) 55 (11.1).0096 COPD 41 (3.2) 14 (2.8).76 Values are presented as number (%) unless otherwise indicated. BMI, body mass index; COPD, chronic obstructive pulmonary disease. Similarly, TE reconstructions took longer than pedicle flaps but were comparable in morbidity, with a rate of 32.2% (n = 59) for the TE group. Risk Factors for Postoperative Complications Univariate analyses compared cases with no complications (n = 1287) to those with 1 or more complications (n = 496) (Table 4). Surgeries resulting in complications had longer operative times than those that did not (6.0 vs 4.1 hours, P <.0001). Postoperative complications were also associated with obesity (P <.001), male sex (P =.048), diabetes (P =.0061), hypertension (P =.0078), and renal comorbidities (P =.0096). Age, number of concurrent procedures, and smoking status did not differ significantly, although age bordered on statistical significance (P =.050). Multivariate logistic regression calculated adjusted OR for operative time and other comorbidities (Table 5). After excluding 30 patients lacking complete data for all variables included in the model, analyses were conducted for the remaining 1753 cases. Operative time was significant (P <.0001), with an odds increase in developing a

5 618 Aesthetic Surgery Journal 34(4) Table 5. Multivariate Logistic Regression: Identifying Predictors of Postoperative Complications Variable Odds Ratio 95% CI P Value Operative time (per hour) <.0001 Age >50 y BMI 30 kg/m Male Diabetes Hypertension Renal comorbidity BMI, body mass index; CI, confidence interval. Table 6. Odds Ratio of Developing a Complication by Quintile of Surgery Duration Quintile Operative Time, h No. (%) of Complications Odds Ratio 95% CI P Value First < (16.3) Reference Second (16.3) Third (23.9) Fourth (35.7) <.0001 Fifth > (48.0) <.0001 n = per quintile. CI, confidence interval. complication of 21% for each additional hour of surgery (95% CI, ). The only other significant risk factor was obesity (OR, 1.38; P =.0075), although men (OR, 1.30; P =.061), diabetics (OR, 1.29; P =.14), and patients older than 50 years (OR, 1.17; P =.18) trended toward increased morbidity. Defining the Cutoff To determine the critical period for significantly increased risk, operative time was separated by quintile (n = ) surgeries, and incidence of overall complications was compared (Table 6 and Figure 1). In reference to surgeries under 2.03 hours (first quintile), morbidity significantly increased only after 3.13 hours (OR, 1.61; 95% CI, ; P =.017), with progressively greater odds increases of 3.05 times after 4.52 hours (95% CI, ; P <.0001) and 4.71 times after 6.77 hours (95% CI, ; P <.0001). There was no change in morbidity below 3.13 hours (OR, 0.98; 95% CI, ; P =.93). Represented graphically, this trend can be fully appreciated in Figure 1. Not only were surgeries in each successive quintile increasingly likely to develop a complication, but this effect was statistically significant for both third versus fourth (OR, 1.84; P <.001) and fourth versus fifth (OR, 1.69; P <.001) quintiles. Stratification by Complication Type Incidences of each complication type were independently compared between surgeries shorter than 3.13 hours (n = 700) and surgeries 3.13 hours and longer (n = 1053) (Table 7). Overall, the effect of operative time on morbidity was not attributed to any single complication type. Longer surgeries were associated with higher rates of wound infection (OR, 2.18; P <.0001), dehiscence (OR, 4.09; P <.0001), erythema (OR, 1.76; P =.0084), necrosis (OR, 2.88; P <.001), seroma (OR, 2.20; P <.001), hematoma (OR, 4.38; P <.001), and delayed wound healing (OR, 3.00; P =.0013). Incidence of VTE approached but did not reach significance (OR, 2.33; P =.055). Stratification by Surgery Type To address the effect of procedural complexity, surgeries were grouped by type before assessing overall morbidity (Tables 8 and 9). For shorter surgeries, morbidity was compared with the 3.13-hour cutoff (Table 8). For longer procedures, surgeries corresponding to the top quintile ( 6.77 hours) were compared with those below it (Table 9). As a whole, operative duration continued to be a risk factor. Prolonged surgeries were associated with more postoperative complications for lipectomy (OR, 2.46; 95% CI, ; P <.001), pedicle

6 Hardy et al 619 Figure 1. Impact of operative time on overall morbidity. Each group represents operative times divided into quintiles (n = per group). Adjusted odds ratios and 95% confidence intervals (represented by error bars) are in reference to the first quintile (<2.03 hours), with P values given within the corresponding column. Horizontal bars indicate significant differences between consecutive groups. *P <.05. ***P <.001. flap (OR, 1.60; 95% CI, ; P =.023), autologous breast reconstruction (OR, 2.01; 95% CI, ; P =.022), TE breast reconstruction (OR, 2.96; 95% CI, ; P =.014), and other breast surgery (OR, 3.05; 95% CI, ; P =.0077). Longer free flaps and rhytidectomies were not significantly different, perhaps due to the small number of patients in these groups (n = 69 and n = 35, respectively). Discussion In plastic surgery, there is a dearth of current literature focusing on operative time, although this subject is briefly addressed in 2 recent studies on breast reconstructions from the National Surgical Quality Improvement Program (NSQIP) data sets. 6,7 Fischer et al 6 found that odds of developing wound complications doubled for surgeries with prolonged operative time, defined as duration greater than 1 standard deviation (SD) above the mean. However, this was done without reporting the times used to discriminate between prolonged and shorter surgeries, and thus the article did not provide clinicians with a practical guide. The other study, by Hanwright et al, 7 demonstrated a 26% rise in odds of morbidity per hour of surgery, which corroborates our data showing a 21% rise. Although this latter study offered more information, it provided only a general overview without delineating change in risk at different time periods. The NSQIP data sets allow for largescale, multicenter analyses with the potential for generalizability; however, neither study looked at procedures other than breast reconstruction nor provided a thorough understanding of the impact of operative time. We addressed these issues by covering a diverse range of surgeries and comparing complication risks across different lengths of time. One of our main goals was to define a true cutoff, after which morbidity risk significantly increases. Some previous studies have relied on an arbitrary time limit, with 6 hours being the most common. 8,9,11 One of the earliest references in plastic surgery to the 6-hour limit was in 1972 by Howland and Schweizer. 8 Without investigating surgeries less than 6 hours in duration, they reported an increased risk of cardiovascular, renal, and pulmonary complications for each hour after 6 hours. In fact, the American Society of Plastic Surgeons (ASPS) Patient Safety Committee published an advisory in 2009, recommending that surgeons keep their operations under 6 hours in an ambulatory setting, despite the lack of evidence to support this. 11 Although the recommendation for a 6-hour limit may be solely convention, it is important to note that this guideline seems to stem from a consensus regarding the risk of complications more severe than the ones we studied, with the exception of VTE. With this in mind, we saw no change in the rate of complications until around 3 hours of surgery, after which the odds increased by 1.6 times. Each successive interval of operative time was accompanied by a concomitant rise in complications, with an odds increase of 3 times after 4.5 hours and nearly 5 times after 6.8 hours. In terms of change in actual rate of complications, the effect was still nontrivial: surgeries under 3 hours had a complication rate of 16.3%, while those over 6.8 hours had a rate of nearly 50%. Our finding of a 3-hour cutoff seems to contradict 2 studies in which there was no increase in the incidence of major complications for surgeries with anesthesia times lasting longer than 4 hours compared with times under 4 hours. 12,13 However, the major complications examined included pulmonary embolism, cardiac complication, and death, and so the results of these studies are likely not applicable to ours. The primary issue when considering a broad range of surgeries is that complexity of procedure confounded with operative time may be the true cause of the observed increase in morbidity. This argument was made by Fogarty et al, 9 claiming that because head and neck surgeries had higher rates of complications than breast and limb surgeries despite having similar operative times, the type of procedure caused the disparity. Indeed, we found that in particular, facial rejuvenations combining multiple procedures (the rhytidectomy group) were relatively long yet had low rates of complications. It makes sense that delicate procedures on small areas like the face requiring limited manipulation would have less morbidity than large flaps used in breast reconstruction or extensive

7 620 Aesthetic Surgery Journal 34(4) Table 7. Effect of Operative Time on Individual Complications Complication <3.13 Hours, No. (%), n = Hours, No. (%), n = 1053 Odds Ratio 95% CI P Value Infection 39 (5.6) 120 (11.4) <.0001 Dehiscence 14 (2.0) 82 (7.8) <.0001 Erythema 32 (4.6) 86 (8.2) Necrosis 16 (2.3) 70 (6.6) <.001 Seroma 29 (4.1) 94 (8.9) <.001 Hematoma 6 (0.9) 36 (3.4) <.001 Delayed wound healing 11 (1.6) 48 (4.6) VTE 7 (1.0) 23 (2.2) CI, confidence interval; VTE, venous thromboembolism. Table 8. Overall Morbidity for Shorter Procedures: Comparing Surgery Lengths Above and Below 3.13 Hours No. of Cases dissections commonly encountered in excisional body contouring procedures. Undoubtedly, surgery type is a determinant for postoperative complications. However, we addressed this issue by stratifying according to surgery type, finding that operative time was still an independent risk factor of morbidity with the exception of the rhytidectomy and free flap groups, both of which had a small number of patients. Even so, surgery duration is difficult to disentangle from procedural complexity, and we admit that our stratification was incomplete, owing to many combined surgeries and the nature of the categories. For example, our lipectomy group included abdominoplasties, which tend to be longer and have higher morbidity than other types of excisional body contouring procedures. 14,15 It is well established that the incidence of infection increases with prolonged operative time, 1-4,16-19 but evidence for other complication types is scarce. We found that in addition to infection, surgeries longer than 3 hours were associated with higher rates of dehiscence, erythema, necrosis, seroma, hematoma, and delayed wound healing. The only complication not significant was VTE, although prolonged surgeries trended toward higher rates of VTE (P =.055). No. (%) of Complications Surgery Type < < Odds Ratio 95% CI P Value Lipectomy (12.5) 69 (25.7) <.001 Pedicle flap (26.4) 103 (37.1) TE breast reconstruction (19.1) 49 (37.7) Other breast surgery (8.4) 16 (22.5) CI, confidence interval; TE, tissue expander. Interestingly, another NSQIP study on breast reconstruction found that odds of developing a VTE increased by 4.36 times for surgeries over 3 hours. 20 A study on arthroplasty reported a similar odds increase of VTE for surgeries with anesthesia time 3.5 hours or longer. 21 This suggests that perhaps we did not have enough events (n = 30) to find an effect, and our study would likely have benefited from a larger cohort. Ideally, we would have also investigated individual complications for each type of procedure: for example, hematomas are common in rhytidectomies, 22 while dehiscence is more of a concern for abdominoplasties. 23 We adjusted for other morbidity risk factors using multivariate regression, but some variables were not taken into account. For instance, we did not look at race, socioeconomic status, or surgeon performing the operation, all of which have been linked to longer operative times. 24,25 In addition, like all retrospective studies, there are inherent biases in the way complications are defined and recorded. Last, this is a single-center study; our results may not be relevant to other institutions. For these reasons, future research involving a multicenter, prospectively maintained database should be conducted to thoroughly investigate the effects of operative time.

8 Hardy et al 621 Table 9. Overall Morbidity for Longer Procedures: Comparing Surgery Lengths Above and Below 6.77 Hours No. of Cases No. (%) of Complications Surgery Type < < Odds Ratio 95% CI P Value Free flap (47.6) 26 (54.2) SMAS flap rhytidectomy (15.0) 2 (13.3) Autologous breast reconstruction (36.6) 76 (53.5) CI, confidence interval; SMAS, superficial musculoaponeurotic system. Conclusions To our knowledge, this is the first study that specifically addresses operative time as an independent risk factor for plastic surgery morbidity with the goal of establishing a cutoff. We report that operative duration significantly influences morbidity only after 3 hours, with progressively increasing odds of developing a complication after this critical period. This trend was not due to any single type of complication: wound infection, dehiscence, erythema, necrosis, seroma, hematoma, and delayed healing were all individually associated with prolonged surgery. And although complication rates differed among procedures likely due to the degree of complexity longer operative times still correlated with greater morbidity when stratified by type of surgery. Ideally, risks posed by plastic surgeries should be balanced by the perceived benefit, and it is our recommendation that operative time be a consideration in surgical decision making. However, this is not to say that faster surgeons necessarily have better results or that performing a procedure more quickly will lead to fewer complications. Operative time is among many factors that could affect surgical outcomes. Acknowledgments The authors thank Rachel Hein, Travis Miller, Roberto Cortez, Kendall Anigian, Natalie Sciano, Bhavani Gannavarapu, Min- Jeong Cho, Eric Lazcano, Janeiro Okafor, and Alan Wang for their hard work in generating the original database. They also thank Debby Noble and the research team at UT Southwestern for their valuable insight and endless support. This study would not have been possible without them. Disclosures The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Dr Davis receives grants from ConvaTec (Princeton, New Jersey), Innovative Therapies (Pompano Beach, Florida), ThermoTek (Lakeville, Minnesota), Unilever (Englewood Cliffs, New Jersey), Andrew Technologies (Tustin, California), and Kensey Nash (Exton, Pennsylvania). She is a consultant for Innovative Therapies and ThermoTek. Dr Kenkel is an investigator for Allergan (Irvine, California), Erchonia (McKinney, Texas), and Ultrashape (San Ramon, California) and serves on the Advisory Board for Kythera (Calabasas, California) and Ulthera (Mesa, Arizona). All positions are paid. The other authors have nothing to disclose. Funding The author(s) received no financial support for the research, authorship, and/or publication of this article. References 1. Schwartz SI. Postoperative complications. In: Principles of Surgery (3rd ed.). New York, NY: McGraw-Hill; 1979: Howard JM, Barker WF, Culbertson WR, et al. Postoperative wound infections: the influence of ultraviolet irradiation of the operating room and of various other factors. Ann Surg (Suppl). 1964;160: Lidwell OM. Sepsis on surgical wounds: multiple regression analysis applied to records of post-operative hospital sepsis. J Hyg (Lond). 1961;59: Cruse PJE, Foord R. A five-year prospective study of surgical wounds. Arch Surg. 1973;107: Scott CF Jr. Length of operation and morbidity: is there a relationship? Plast Reconstr Surg. 1982;69: Fischer JP, Nelson JA, Au A, Tuggles CT III, Serletti JM, Wu LC. Complications and morbidity following breast reconstruction a review of 16,063 cases from the NSQIP datasets [published online July 18, 2013]. J Plast Surg Hand Surg. 7. Hanwright PJ, Davila AA, Mioton LM, Fine NA, Bilimoria KY, Kim JYS. A predictive model of risk and outcomes in tissue expander reconstruction: a multivariate analysis of 9786 patients. J Plast Surg Hand Surg. 2013;47(6): Howland WS, Schweizer O. Complications associated with prolonged operation and anesthesia. Clin Anesth. 1972;9: Fogarty BJ, Khan K, Ashall G, Leonard AG. Complications of long operations: a prospective study of morbidity associated with prolonged operative time (>6h). Br J Plast Surg. 1999;52: Elixhauser A, Steiner C, Harris DR, Coffey RM. Comorbidity measures for use with administrative data. Med Care. 1998;36: Haeck PC, Swanson JA, Iverson RE, et al. Evidence-based patient safety advisory: patient selection and procedures in ambulatory surgery. Plast Reconstr Surg. 2009;124(suppl 4):6S-27S.

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