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The value of preoperative lung spirometry test for predicting the operative risk in patients undergoing gastric cancer surgery

Purpose We evaluated the predictive value of preoperative lung spirometry test for postoperative morbidity and the nature of complications related to an abnormal pulmonary function after gastric cancer surgery. Methods Between February 2009 and March 2010, 538 gastric cancer patients who underwent laparoscopic (n = 247) and open gastrectomy (n = 291) were divided into the normal (forced expiratory volume in 1 second [FEV1]/forced vital capacity [FVC] ≥ 0.7, n = 441) and abnormal pulmonary function group (FEV1/FVC < 0.7, n = 97), according to the preoperative lung spirometry test. The predictive value of lung spirometry for postoperative morbidity was evaluated using the univariate and multivariate analysis. Results After surgery, the abnormal pulmonary function group showed a significantly increased incidence of local (29.9% vs. 18.1%, P = 0.009) and systemic complications (8.2% vs. 2.0%, P = 0.005) than the normal group. Of local complications, anastomosis leakage and wound complication were found to be more common in the abnormal pulmonary function group. In the univariate and multivariate analysis, an abnormal pulmonary function was an independent predictor for postoperative local complication (odds ratio, 1.75; 95% confidence interval, 1.03 to 2.97) after adjusted by old age, total gastrectomy, open surgery, and tumor-node-metastasis stage. Meanwhile, an old age and a history of pulmonary disease were independent predictors for systemic complication. Conclusion Preoperative lung spirometry is a simple and useful means to predict postoperative morbidity after gastric cancer surgery. In view of its simplicity and low cost, we recommend adding preoperative lung spirometry test to assess the operative risk and aid in proper perioperative treatment planning.


INTRODUCTION
Gastric carcinoma is largely a disease of old age, and thus surgical patients often have various underlying comorbidities at the time of operation [1]. Accordingly, a thorough preoperative assessment of underlying disease is crucial for making proper treatment decision and predicting possible postoperative complications [2]. Pulmonary comorbidity is one of the most common underlying problems, which is widely believed to increase the risk of postoperative respiratory complications [3]. Although it is assumed that pulmonary disease may also increase the risk of surgical complications due to the impaired wound healing process associated with tissue hypoxia, only a few studies have demonstrated the association between pulmonary comorbidity and surgical complications in patients undergoing major abdominal surgery [4].
Preoperative screening of pulmonary disease usually depends on the history taking of patients' previous medical history. However, pulmonary disease is seldom diagnosed and treated until patients visit physicians with overt respiratory symptoms. Meanwhile, lung spirometry allows patients with pulmonary abnormality to be objectively screened, and could be useful for predicting operative risk related to an abnormal pulmonary function [5].
In the field of thoracic surgery, preoperative lung spirometry is widely used to select surgical candidates and predict the occurrence of postoperative respiratory complications [6]. However, lung spirometry is not commonly recommended for patients with major abdominal surgery because of its uncertainty about predictive value for postoperative complications [7,8]. In the present study, we have investigated the value of preoperative lung spirometry test for predicting postoperative complications after gastric cancer surgery. We have also sought to investigate which complications may arise after gastric cancer surgery related to an abnormal pulmonary function. Pancreatic fistula was diagnosed based on a continued high amylase concentration in drainage fluid from the peripancreatic area for more than 7 days. Bleeding was diagnosed based on abdominal CT findings or clinical suspicion, due to, for example, bloody abdominal drainage or melana. Types of complications were judiciously defined and recorded according to the diagnostic criteria, and the severities were classified based on the Accordion Severity Grading System of surgical complications [9]. In-hospital mortality was defined as operation-related death within 30 days of surgery or during the period of hospitalization.

Patients and data collection
To evaluate the predictive value of lung spirometry, a comparative analysis was carried out between the normal (n = 441) and the abnormal pulmonary function group (n = 97) with respect to postoperative morbidity and mortality.

Operative procedure and perioperative care
Patients underwent distal or total gastrectomy with regional lymph node dissection, as described by the gastric cancer treatment guideline issued by the Japanese Gastric Cancer Association [11]. Laparoscopic surgery was indicated based on the preoperative tumor staging (cT1-2N0). Billroth I reconstruction was the primary procedure after distal gastrectomy, and Billroth II or Roux-en Y gastrojejunostomy was considered in selected cases, such as wide resection of the stomach. Roux-en Y esophagojejunostomy was performed routinely after total gastrectomy.
All the patients were managed using a standardized clinical pathway protocol. For example, no preoperative mechanical bowel preparation or nasogastric tube was employed. Postoperatively, patients were administered an oral diet from postoperative day 1, and intravenous fluid (20 to 25 mL/kg/day) was administered during the first three postoperative days. Prophylactic antibiotics were administered before skin incision and were continued until 12 hours after surgery. Thromboprophylaxis was performed using a pneumatic intermittent compression device. Hospital discharge was decided based on the fulfillment of the following objective discharge criteria; no evidence of a postoperative complication, the ability to ambulate without assistance, tolerable pain on administration of oral analgesia, the ability to take more than 70% of any given meal, and a willingness to go home.

Statistical analysis
The Student's t-test was used to analyze continuous da- Based on the Accordion Severity Classification System of surgical complications [9].    Based on the spirometric severity classification of pulmonary function [9]. ces of mild and moderate complications were similar in the two groups, but the rate of severe grade complications was significantly higher in patients with an abnormal pulmonary function (12.4% vs. 3.9%, P = 0.001) ( Table 2).     Table 6

DISCUSSION
Preoperative pulmonary function testing is often ordered before major surgery to screen patients for an abnormal pulmonary function [2]. However, unlike a general acceptance of preoperative lung spirometry as an effective tool for predicting operative risk in the field of thoracic surgery, its role, in terms of predicting postoperative morbidity, is somewhat controversial in the field of major abdominal surgery [6]. Some studies have even demonstrated that clinical findings are more predictive of postoperative respiratory complications than pulmonary function test results [12,13]. However, a comprehensive review of pulmonary function testing in the context of abdominal surgery by Lawrence et al. [8]     Values are presented as number (%).  [4]. However, no study has been undertaken to identify as which surgical complications after gastric cancer surgery are related to preoperative abnormal pulmonary function. In the present study, we identified that wound complications and anastomosis leakage were significantly increased in an abnormal pulmonary group. In addition, gastric stasis tended to be more frequent among those with an abnormal pulmonary function (P = 0.075).
Similarly, a large study conducted on identification of the impact of comorbidity on postoperative complications after laparoscopic gastrectomy, revealed a significant increase in wound complications and intestinal obstruction in pulmonary disease [16]. Our study does stimulate questions and the role of hypoxia by an abnormal pulmonary function on anastomosis healing, and this needs to be further investigated by carrying out animal or laboratory study in the future.
In the present study, we classified abnormal pulmonary function using a spirometric airway limitation classification system to diagnose COPD [9], but we found no function [17]. However, these spirometric classifications alone do not reflect symptom severity, disease progression, or prognosis in patients with pulmonary disease [18], and thus, we think perioperative management aimed at optimizing lung function should be considered for any patient with abnormal spirometric findings, regardless of the severity of airway limitation.
Other common comorbidities, such as, cardiovascular, endocrine, and hepatic disease, are likely to be more common in patients with an abnormal pulmonary function, and could contribute to increased postoperative morbidity. Thus, the predictive value of lung spirometry should be evaluated by adjusting for the operative risks associated with these comorbidities. In the present study, no significant differences were observed between the normal and abnormal pulmonary function groups with respect to the incidence of other comorbidities. In addition, comorbidities, such as cardiovascular, endocrine, hepatic, and renal diseases, were not found to significantly increase the risk of postoperative morbidity as per the univariate analysis. However, the impact of comorbidities other than pulmonary disease on surgical outcomes needs to be further evaluated in terms of large studies in which accurate preoperative assessment is implemented.
In the present study, most of the respiratory complica-

CONFLICTS OF INTEREST
No potential conflict of interest relevant to this article was reported.