Ann Thorac Surg 2009;87:412-415. doi:10.1016/j.athoracsur.2008.10.072
© 2009 The Society of Thoracic Surgeons
Original Articles: General Thoracic
Impact of Obesity on Perioperative Outcomes of Minimally Invasive Esophagectomy
Arman Kilic, BS,
Matthew J. Schuchert, MD,
Arjun Pennathur, MD,
Karl Yaeger, BS,
Vikram Prasanna, BS,
James D. Luketich, MD,
Sebastien Gilbert, MD*
Heart, Lung, and Esophageal Surgery Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
Accepted for publication October 23, 2008.
* Address correspondence to Dr Gilbert, University of Pittsburgh Medical Center Presbyterian, Suite C-800, 200 Lothrop St, Pittsburgh, PA 15213 (Email: gilbsx{at}upmc.edu).
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Abstract
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Background: Abnormal body mass index has been targeted as a predictor of complications after major surgery. The aim of this study was to review the impact of obesity on perioperative outcomes after minimally invasive esophagectomy.
Methods: This study was a single-institution retrospective review of patients undergoing minimally invasive esophagectomy for high-grade dysplasia or cancer of the esophagus between 1999 and 2004. A body mass index of 30 or greater was considered obese. Patients with a body mass index less than 18.5 were excluded because of the potentially adverse effects of malnutrition on outcomes.
Results: A total of 282 eligible patients were identified. There were 84 obese and 198 nonobese patients (mean body mass index = 34.5 versus 25.5; p < 0.0001). Preoperative demographics, comorbidities, and cancer status were similar, except for a higher prevalence of diabetes (p = 0.002), lower prevalence of peripheral vascular disease (p = 0.045), and lower prevalence of stage III disease in the obese group (p = 0.044). Operative time was significantly longer in obese patients (375 versus 301 minutes; p = 0.0001), and estimated blood loss was similar (433 versus 377 mL, obese versus nonobese, respectively). There were 5 (1.8%) overall 30-day perioperative mortalities, with no differences between the groups. Overall major (obese, 23 [27.5%] versus nonobese, 68 [34.3%]) and minor (obese, 23 [27.5%] versus nonobese, 65 [32.8%]) complication rates were also similar. Furthermore, there were no significant differences in any individual complications. There was no difference in median intensive care unit stay (obese, 1 day versus nonobese, 2 days) or overall hospital stay (obese, 7 days versus nonobese, 8 days).
Conclusions: Obesity was associated with longer operative times. Our review suggests that obesity is not a risk factor for mortality, postoperative complications, or length of hospitalization after minimally invasive esophagectomy.
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Introduction
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Data from the 1999–2002 National Health and Nutrition Examination Survey estimates that the prevalence of obesity (body mass index [BMI] > 30 kg/m2) among American adults has doubled from 15% to 31% during the last three decades [1]. In addition, there has been an increasing number of overweight (BMI 25 to 29.9 kg/m2) individuals. In fact, more than 120 million Americans are now estimated to be overweight or obese, a proportion that comprises approximately 65% of the adult population [1]. With these trends, surgeons will undoubtedly encounter an increasing proportion of obese patients. As such, it is important to report surgical outcomes in this cohort given the known adverse effects of obesity on general health [2]. Recent studies of open esophagectomy showed that obesity did not increase the risk of major morbidity or mortality, as perhaps initially thought [3, 4]. The aim of this study was to determine whether obesity had a significant impact on perioperative outcomes after minimally invasive esophagectomy (MIE).
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Material and Methods
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A single-institution retrospective review of patients undergoing MIE for cancer of the thoracic esophagus between 1999 and 2004 was conducted. This study was approved by the institutional review board, and patient consent was waived. Preoperative height and weight data were obtained from electronic medical records and clinical charts, and patients with a BMI of greater than 30 kg/m2 were defined as obese. Patients in the overweight (BMI 25.0 to 29.9 kg/m2) and normal (BMI 18.5 to 24.9 kg/m2) categories were defined as nonobese. Those with a BMI of less than 18.5 kg/m2 (underweight) were excluded because of the potentially adverse effects of poor nutritional status on operative outcomes.
The MIE operative technique was similar to that described previously [5]. In eligible patients, preoperative variables including age, sex, race, smoking history, alcohol history, comorbidities (diabetes, stroke, congestive heart failure, arrhythmia, chronic obstructive pulmonary disease, renal failure, coronary artery disease, peripheral vascular disease, hypertension), cancer histology, cancer stage, and neoadjuvant chemotherapy or radiation were collected. Perioperative outcomes included operative time, estimated blood loss, intensive care unit stay, 30-day mortality, major and minor complications, and length of stay. Major complications included anastomotic leak, myocardial infarction, gastric tube necrosis, delayed gastric emptying, chylothorax, respiratory failure requiring reintubation or tracheostomy, tracheal perforation, deep vein thrombosis, pulmonary embolism, pneumonia, empyema, recurrent laryngeal nerve injury, cerebrovascular accident, sepsis, pericardial effusion, and acute renal failure. Minor complications included atrial fibrillation, pleural effusion requiring drainage, pneumothorax, wound infection, cellulitis, and Clostridium difficile colitis.
Statistical analyses were conducted with SPSS software version 16.0 (SPSS Inc, Chicago, IL). Comparisons were performed using unpaired Student's t test for continuous variables and Fisher's exact test for discrete variables. Two-tailed probability values less than 0.05 were considered significant.
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Results
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A total of 284 patients underwent MIE for high-grade dysplasia or cancer of the thoracic esophagus between 1999 and 2004. Two (0.7%) patients were excluded because of a low BMI (<18.5 kg/m2). Of the remaining 282 patients, 84 (29.8%) were obese. Except for a higher prevalence of diabetes (24 of 84 [29%] versus 25 of 198 [13%]; p = 0.002), a lower prevalence of peripheral vascular disease (1 of 84 [1%] versus 14 of 198 [7%]; p = 0.045), and a lower prevalence of stage III disease (17 of 84 [20%] versus 65 of 198 [33%]; p = 0.044), obese patients had similar characteristics with the nonobese (Table 1).
Obese patients experienced a similar mean estimated blood loss (433 versus 377 mL; p = 0.35) but significantly longer operative time (375 versus 301 minutes; p = 0.0001) as compared with the nonobese (Table 2). Median intensive care unit stay (1 day in obese versus 2 days in nonobese; p = 0.75) and length of hospital stay (7 days versus 8 days; p = 0.31) were comparable. Thirty-day operative mortality was 1.8% with no differences between the cohorts. Obese patients had a lower 90-day mortality (obese, 1 [1.2%] versus nonobese-15 [7.6%]; p = 0.045). Overall major (obese, 23 [27.5%] versus nonobese, 68 [34.3%]; p = 0.27) and minor (obese, 23 [27.5%] versus nonobese, 65 [32.8%]; p = 0.40) complication rates were also similar. Furthermore, there were no significant differences in any individual complications (Table 3).
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Comment
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The prevalence of obesity has increased at a significant rate in the last several decades and is projected to continue climbing in oncoming years [6]. This may translate into a higher proportion of obese patients presenting for medical care and surgical procedures. For instance, in this study, nearly one third of patients undergoing MIE were obese. Because esophagectomy can result in significant mortality and morbidity, gathering information on potential risk factors may allow the surgeon to offer a more educated opinion of the expected outcomes of surgery and perhaps anticipate or prevent adverse events [7]. The present data suggest that, although associated with a longer operative time, obesity may not have a significant impact on blood loss, morbidity, perioperative mortality, or length of hospitalization after MIE. We realize the limitations and biases inherent to the present study design and acknowledge that a prospective analysis would be necessary to validate these observations.
A recent review of open esophagectomy demonstrated similar rates of mortality, as well as major respiratory and wound complications, between obese and nonobese patients [3]. Rates of overall respiratory complications, pleural effusions, and anastomotic leaks were significantly higher in the obese, however. Aside from a higher rate of recurrent laryngeal nerve injury and greater operative blood loss, similar surgical outcomes were demonstrated between obese and nonobese patients undergoing transhiatal esophagectomy in another retrospective review study [4]. In pulmonary surgery, a review of outcomes after resection of non–small cell lung cancer demonstrated that obese patients had a higher rate of acute renal failure and a trend toward fewer pulmonary complications [8]. Moreover, a prospective analysis of more than 6,300 patients showed that in elective general surgery procedures, obesity was not a significant risk factor for perioperative morbidity or mortality [9].
The longer operative time observed in the present study was not surprising and likely reflects anesthetic and surgical challenges specific to obese patients. In contrast to other reports [3, 4], this cohort of obese patients experienced a similar intraoperative blood loss as compared with the nonobese. This may be related to the use of a minimally invasive approach. The average blood loss in this report was less than what has been reported in case series of transthoracic or transhiatal esophagectomy [10–16]. This is also supported by other investigators who compared open and minimally invasive approaches and concluded that among other advantages, minimally invasive surgery reduced operative blood loss and transfusion requirements [17].
Atrial fibrillation is a well-known complication of esophagectomy with an estimated incidence of approximately 20% [18]. There were no differences in the incidence of atrial fibrillation in the obese versus nonobese in this study. The pathogenesis of atrial fibrillation after esophagectomy is not clearly understood, although greater intraoperative blood loss and more-extensive thoracic dissection have been noted to increase the risk [19].
In patients with a large neck (who often are obese), exposure and manipulation of the cervical esophagus is more difficult and could theoretically lead to a higher rate of cervical anastomotic leak or recurrent laryngeal nerve injury. No such differences were noted in this study. This is in contrast to other series showing either a higher rate of anastomotic leak or recurrent laryngeal nerve injury in obese patients [3, 4]. During MIE, regardless of the patient's body habitus, early division of the right vagal trunk, limited lymph node dissection above the level of the azygous vein, and avoidance of retraction in the left tracheoesophageal groove are methods used to minimize the risk of recurrent laryngeal nerve injury [5].
As in other reports of esophagectomy in the obese, the rate of wound complications and gastric conduit necrosis were not influenced by obesity, even though a greater proportion of obese patients had diabetes [3, 4]. We realize, however, that the number of patients included may have been insufficient to evaluate these relatively rare complications. In fact, in a large review of general surgery patients, the only perioperative outcome that seemed to be affected by obesity was the rate of wound complications [8]. In light of the above results and with the limitations of the study design taken into account, it appears that obesity is not a significant risk factor for complications in patients undergoing MIE.
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Abstract
Introduction
