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Abstract

Objectives

To identify predictors of postoperative pulmonary complications (PPCs) in patients aged ≥60 years who underwent laparoscopy-assisted gastrectomy (LAG), and to examine the value of preoperative spirometry to predict PPCs.

Methods

Patients with preoperative spirometric results who underwent LAG were retrospectively studied. Spirometry included four parameters: forced expiratory volume in 1 s; functional vital capacity; mean forced expiratory flow during middle of functional vital capacity; peak expiratory flow rate.

Results

Of 213 patients, overall incidence of PPCs was 19.2%. Abnormal spirometry findings were not identified as an independent predictor of PPCs using multivariate logistic regression analysis. Age was found to be the only independent predictor of PPCs out of all variables evaluated. Separate assessment of individual spirometric parameters using receiver-operating curve analyses indicated poor diagnostic accuracy.

Conclusions

Preoperative spirometry was not reliably predictive of PPCs, either as combined or individual parameters, in patients aged ≥60 years who underwent LAG. These results do not support routine use of spirometry to stratify risk of PPCs in this surgical population.

Keywords

Gastric cancer laparoscopy-assisted gastrectomy spirometry postoperative complications

Introduction

The incidence of postoperative pulmonary complications (PPCs) in patients undergoing upper abdominal surgery reportedly ranges between 12% and 58%.^1,2 In addition to surgery-related risk factors, advanced age (≥60 years) is a consistently reported predictor of PPCs.^1,3,4 PPCs directly contribute to increased morbidity and mortality, duration of hospital stay and use of resources,^4,5 therefore the need for a preoperative screening test to identify patients at heightened risk of complications has been emphasized. Although there is controversy over the utility of routine spirometry in every patient undergoing upper abdominal surgery, many clinicians order routine spirometry for elderly patients being prepared for upper abdominal surgery.⁶

Laparoscopy-assisted gastrectomy (LAG) has increasingly been employed for the treatment of gastric cancer, and as clinical experience has increased, indications for LAG have been broadened to include patients of advanced age.⁷ LAG appears to be advantageous in relation to postoperative respiratory function as it requires a relatively small skin incision,⁸ however, the usefulness of preoperative spirometry for predicting PPCs following such surgery has not been examined, particularly in elderly patients.

The present study retrospectively investigated the influence of possible risk factors on the development of PPCs in patients aged ≥60 years who underwent LAG, and assessed the value of preoperative spirometric results in predicting PPCs.

Patients and methods

Study population

This retrospective cohort study examined the medical records of patients aged ≥60 years who underwent elective LAG for gastric cancer between January 2008 and December 2012 at the Samsung Medical Centre, a tertiary referral hospital in Seoul, Republic of Korea. The LAG procedure comprised either laparoscopy-assisted distal gastrectomy or laparoscopy-assisted total gastrectomy, depending on the location of the tumour. To obtain a more accurate comparison regarding PPCs, laparoscopic wedge resection or combined resection of adjacent organs, such as gallbladder or spleen, were excluded.

The study was approved by the Institutional Review Board of Samsung Medical Centre, Seoul, Republic of Korea (IRB file No.: 2012-11-056-001; approval date: 30 December 2012). The Institutional Review Board concluded that patient consent was not required, since the study was a retrospective analysis of data obtained during routine treatment.

Surgical procedures and postoperative management

A five-trocar technique was used for laparoscopic procedures. During surgery, anaesthesia was similar for all patients and comprised inhaled sevoflurane (2–4%) alone or sevoflurane (1–2%) supplemented with remifentanil continuous intravenous infusion (0.02–0.2 µg/kg per min).

Carbon dioxide (CO₂) pneumoperitoneum was maintained at an insufflation pressure of 12 mmHg. Lymph nodes along the left gastric artery, common hepatic artery and coeliac axis were dissected in addition to D1 lymph nodes, using laparoscopic coagulation shears (HARMONIC ACE^TM Curved Shears; Ethicon Endo-Surgery, Guaynabo, Puerto Rico). The right upper trocar incision was transversely extended to 4–6 cm, the stomach was externalized through the incision and then dissected. Reconstruction was performed extracorporeally using a circular stapler (DST Series™ EEA™ Stapler; Ethicon Endo-Surgery, Mansfield, MA, USA).

Following surgery, all patients were routinely managed using a standardized postoperative protocol: (i) intravenous patient-controlled analgesia using fentanyl (1200 µg) and ketorolac (120 mg) mixed with normal saline in a total volume of 60 ml. The basal infusion rate, bolus dose and lockout interval were 0.5 ml/h, 0.5 ml and 15 min, respectively; (ii) breathing exercises and incentive spirometry training following surgery, encouragement of early ambulation and chest physical therapy when indicated; (iii) clear liquid diet after the first flatus; (iv) discharge after tolerance of a soft diet for 2 days if no surgical or systemic complications occurred.

Spirometry

Spirometry was performed as recommended by the American Thoracic Society⁹ using a Vmax 22 pulmonary function test system (SensorMedics, CA, USA). The spirometry assessment included four parameters: FEV₁ (forced expiratory volume in 1 s); FVC (functional vital capacity); FEF_25–75% (mean forced expiratory flow during middle of FVC); PEFR (peak expiratory flow rate). Absolute values of these four parameters were obtained, and the percentages of predicted values were calculated.¹⁰ Patients were spirometrically classified as normal or abnormal according to the following cut-off points commonly accepted in clinical practice: normal, ≥80% of predicted values for FVC and FEV₁, and ≥70% for FEV₁/FVC; abnormal, <80% of predicted values for FVC and FEV₁, and <70% for FEV₁/FVC.¹¹

Definitions of outcomes and variables

A research fellow (Y-K. Y.) determined the pulmonary outcomes through a review of postoperative records without knowledge of the results of preoperative evaluations, including spirometry. PPCs were diagnosed by clinical and radiological examinations during hospitalization. PPCs were defined as any of the following: atelectasis; pulmonary embolism; bronchitis; pneumonia; and/or acute respiratory failure. Daily assessment of patients’ respiratory conditions were performed at the Samsung Medical Centre until discharge, according to a standardized protocol that included a clinical examination of pulmonary symptoms (e.g., cough, dyspnoea, excessive sputum production, chest pain, wheezing, crackles, and fever of ≥38.5°C), chest X-radiography and analysis of venous white blood cell count on postoperative day 1 or 2.

Respiratory symptoms on the day before surgery, history of smoking, American Society of Anesthesiologists (ASA) physical status,¹² and duration of surgery and anaesthesia were noted. The study cohort was dichotomized, based on the ASA physical status classification system (class I, normal healthy patient versus class ≥II, patient with mild systemic disease), where ASA class ≥II was regarded as a group at higher risk of postoperative complications compared with ASA class I (control group).¹² Current smokers were defined as individuals having smoked ≥cigarette per day for >1 year, within ≥6 weeks before surgery (as smoking cessation ≥6–8 weeks prior to elective surgery has been shown to improve postoperative pulmonary function).¹³ Duration of postoperative hospital stay and days to first flatus were also recorded.

Statistical analyses

Statistical analyses were performed with the SPSS® software package, version 18.0 (SPSS Inc., Chicago, IL, USA) for Windows® and MedCal software package, version 12.0 (MedCal Software, Mariakerke, Belgium) for Windows®. First, univariate characteristics between patients with and without PPCs were compared using the unpaired t-test or χ²-test. Secondly, forward stepwise multivariate logistic regression analysis was conducted to identify independent predictors of PPCs. Any variables that were significant at P ≤ 0.2 in the univariate analysis were candidates for entry into multivariate analysis. Odds Ratios (OR), 95% confidence intervals (CI), and P-values of the independent predictors were calculated. Thirdly, receiver-operating characteristic (ROC) curves were constructed for individual spirometric parameters that were related to PPCs in the univariate analysis, to explore the tradeoffs between the sensitivity and specificity of each parameter. The optimal cutoff points of each test were then determined at the maximum area under (AUC) the corresponding ROC curve. Lastly, the discriminative performances of these spirometric parameters were assessed by calculating the AUC for each ROC curve. AUC values were compared using a nonparametric method,¹⁴ based on the Mann–Whitney U-test. In all analyses, P < 0.05 indicated statistical significance.

Results

Records of 215 patients were examined. According to Samsung Medical Centre policy, all patients aged ≥60 years undergoing elective laparoscopic or open gastrectomy should receive preoperative spirometry, however, two patients did not. Thus, the records of 213 patients (124 male, 89 female) who underwent elective LAG with preoperative spirometric results were analysed in the present study. Mean ± SD age of all patients at surgery was 67.0 ± 6.3 years (range, 60–90 years). Overall incidence of PPCs was 19.2% (41/213) (Table 1). The most frequent PPC observed was symptomatic and radiologically documented atelectasis (15.5% of all patients; 80.5% of all PPCs). Additional pulmonary complications included bronchitis (n = 7) and pneumonia (n = 4). Atelectasis and pneumonia were observed concurrently, in three patients. No case of acute respiratory failure or pulmonary embolism occurred.

Table 1.

Characteristics of 213 patients who underwent elective laparoscopy-assisted gastrectomy for gastric cancer, with or without postoperative pulmonary complications (PPCs).

Characteristic	With PPCs	Without PPCs	Statistical significance
Characteristic	n = 41	n = 172	Statistical significance
Sex, male/female	27/14	97/75	NS
Age, years	69.1 ± 7.2	66.5 ± 5.9	P = 0.034
Current smokers/ex- or nonsmokers	10/31	39/133	NS
Respiratory symptoms, yes/no	7/34	15/157	NS
BMI, kg/m²	23.3 ± 4.6	23.6 ± 2.4	NS
ASA physical status, I/ ≥II	15/26	98/74	P = 0.019
Spirometry findings, abnormal/normal	15/26	33/139	P = 0.017
Duration of surgery, min	182.2 ± 59.9	173.7 ± 49.2	NS
Duration of anaesthesia, min	220.7 ± 64.2	214.0 ± 49.2	NS
Time to first flatus, days	3.7 ± 0.7	3.3 ± 0.9	P = 0.015
Postoperative hospital stay, days	7.6 ± 0.8	7.5 ± 1.0	NS

Data presented as mean ± SD or n of patients.

NS, no statistically significant between-group difference (P ≥0.05; unpaired t-test or χ²- test).

BMI, body mass index; ASA, American Society of Anesthesiologists.

Spirometry findings showed abnormalities in 22.5% (48/213) of patients, 31.3% (15/48) of whom experienced PPCs. Abnormal spirometry results and ASA class ≥2 were significantly associated with PPCs in univariate analyses (P < 0.05) (Table 1), however, significance was not confirmed using multivariate logistic regression analysis. Of four variables (age, ASA class ≥2, presence of respiratory symptoms and abnormal spirometry) entered into multivariate logistic regression analysis, age was the only independent predictor of PPCs (OR 1.065, 95% CI 1.011, 1.121).

Analysis of respiratory function parameters revealed FEV₁ (% of predicted), FEV₁/FVC, FEF_25–75%, and FEF_25–75% (% of predicted) to be significantly different between patients with or without PPCs (P < 0.05) (Table 2). Predictive accuracies for PPCs were compared using ROC curves (Figure 1). For individual optimal cutoff points, the AUC values used to predict PPCs for FEV₁ (% of predicted), FEV₁/FVC, FEF_25–75%, and FEF_25–75% (% of predicted) were all <0.7, indicating a poor degree of accuracy (Table 3).

Figure 1.

Receiver operating characteristic curves of spirometric tests for predicting postoperative pulmonary complications (PPCs) in 213 patients who underwent elective laparoscopy-assisted gastrectomy for gastric cancer, with or without PPCs. (♦) optimal cutoff point of each test. FEV₁ (% of predicted), percentage predicted values for forced expiratory volume in 1 s; FVC, functional vital capacity; FEF_25–75%, mean forced expiratory flow during the middle of the FVC; FEF_25–75% (% of predicted), percentage predicted values for FEF_25–75%.

Table 2.

Preoperative respiratory function characteristics of 213 patients who underwent elective laparoscopy-assisted gastrectomy for gastric cancer, with or without postoperative pulmonary complications (PPCs).

Respiratory function characteristic	With PPCs	Without PPCs	Statistical significance
Respiratory function characteristic	n = 41	n = 172	Statistical significance
FVC, l	3.4 ± 0.7	3.5 ± 0.8	NS
FVC, % of predicted	98.4 ± 15.0	102.6 ± 14.0	NS
FEV₁, l	2.4 ± 0.5	2.6 ± 0.6	NS
FEV₁, % of predicted	101.5 ± 17.7	109.0 ± 18.5	P = 0.020
FEV₁/FVC, %	72.6 ± 8.5	75.8 ± 8.3	P = 0.031
FEF_25–75%, l/s	1.8 ± 0.8	2.3 ± 0.9	P = 0.006
FEF_25–75%, % of predicted	77.9 ± 33.0	91.5 ± 34.8	P = 0.024
PEFR, l/s	6.5 ± 2.2	7.0 ± 2.1	NS
PEFR, % of predicted	101.2 ± 27.1	108.4 ± 23.8	NS

Data presented as mean ± SD.

NS, no statistically significant between-group difference (P ≥0.05; unpaired t-test).

FVC, functional vital capacity; FEV₁, forced expiratory volume in 1 s; FEF_25–75%, mean forced expiratory flow during the middle of the FVC; PEFR, peak expiratory flow rate.

Table 3.

Comparison between receiver-operating characteristic curves of spirometric test results for predicting postoperative pulmonary complications (PPCs) in 213 patients who underwent elective laparoscopy-assisted gastrectomy for gastric cancer, with or without PPCs.

Spirometric test	AUC	SE	95% CI
FEV₁ ≤ 91% of predicted	0.595	0.053	0.525, 0.661
FEV₁/FVC ≤ 73%	0.614	0.050	0.545, 0.679
FEF_25–75% ≤ 1.9 l/s	0.632	0.047	0.564, 0.697
FEF_25–75% ≤ 87% of predicted	0.615	0.049	0.547, 0.681

AUC, area under the curve; CI, confidence interval; FEV₁, forced expiratory volume in 1 s; FVC, functional vital capacity; FEF_25–75%, mean forced expiratory flow during the middle of the FVC.

There were no statistically significant differences between the spirometric tests (nonparametric method¹⁴ based on Mann–Whitney U-test).

Discussion

Increased risk of PPCs following upper abdominal surgery under general anaesthesia, such as gastrectomy, has been well documented.^1–4 Surgery involving incision sites near the diaphragm causes a reduction in the vital capacity and limits diaphragmatic motion, thereby resulting in alveolar collapse, early airway closure, ventilation/perfusion abnormalities, decreased mucus clearance and increased bacterial colonization.¹⁵ All of these mechanisms contribute to the development of PPCs.

Few investigations concerning postoperative respiratory function following LAG have been conducted. Two randomized studies^8,16 demonstrated that pulmonary function is more favourably preserved in LAG compared with open gastrectomy, due to a relatively short skin incision (4–6 versus 15–20 cm). CO₂ pneumoperitoneum may have an adverse effect on intraoperative respiratory function, although it does not complicate postoperative respiratory function, even in patients with moderate chronic obstructive pulmonary disease (FEV₁ value 50–80% of predicted value) undergoing LAG.¹⁷

The present study investigated surgical patients aged ≥60 years, as this population is at high risk of PPCs following both open^1–3 and laparoscopic¹⁸ abdominal surgery. Physiologically, ageing is associated with a gradual loss of pulmonary reserve capacity, even in individuals without obvious underlying comorbidities.¹⁹ The results of the present study support these findings, since age was identified as the only independent risk factor associated with PPCs among the variables evaluated.

The usefulness of spirometry as a screening test to stratify PPC risk was assessed in the present study because it is readily available, easy to apply, reproducible and applicable to a large number of patients. Like many gastric surgeons, surgeons in the Samsung Medical Centre routinely order preoperative spirometry for elderly patients undergoing LAG, as they consider this surgical population to have multiple risk factors, including old age, duration of surgery >2–3 h and close proximity of incision site to the diaphragm.^1,4 The value of routine spirometry prior to all types of abdominal surgery, however, remains unclear. When limited to upper abdominal surgery, preoperative spirometry appears to be useful for stratification of PPC risk,^20,21 although the present study on laparoscopic upper abdominal surgery revealed contrasting results. These findings suggest that spirometry may not detect clinically occult patients in whom the PPC risk is high, or that occult pulmonary diseases detected by spirometry are not clinically important following LAG, perhaps due to a lesser decline in postoperative pulmonary function. There are potentially multiple predictors for PPCs, so it may be difficult to predict PPCs reliably, based on spirometry alone, although age was the only proven predictor among the variables studied in the present study. Thus, it would be imprudent to assume that the excellent diagnostic performance of spirometry for functional lung disease translates into good predictive performance for PPCs, in individual surgical patients.

Cigarette smoking has repeatedly been revealed as a risk factor for PPCs in abdominal laparotomy,^1,2,4 however, current smoking history (with a definition similar to the previous studies) had no impact on the rate of PPCs following LAG in the present investigation. These results concur with one published study involving abdominal laparoscopic procedures, which demonstrated that current smoking history had no effect on PPC rates,²² and recommended that patients with a current smoking history who are scheduled for surgery should undergo laparoscopic surgery where feasible.

The time to first flatus was delayed in patients with PPCs compared with those without PPCs in the present study, however, duration of postoperative hospital stay was similar between the groups, which is inconsistent with previous investigations.^4,5 This may be attributed to the routine use of chest physical therapy in patients with PPCs in the present investigation. These interventions are especially beneficial for preventing atelectasis (80.5% of all PPCs in the present study) progressing to more severe forms of PPCs.¹⁵ In addition, LAG is associated with lower rates of postoperative pain than open gastrectomy, which can improve patients’ compliance with chest physical therapy. Thus, such a beneficial effect may be accelerated.

The present study may be limited by the relatively small study population, which may not be large enough to perform adjustment of covariates, such as the differences between perioperative management and comorbidities, and also by errors introduced due to the retrospective nature of the study, all of which may have influenced outcomes.

In conclusion, the present study demonstrated that preoperative spirometry results are not reliably predictive of PPCs, either as combined or individual lung function parameters, in patients aged ≥60 years who are scheduled to undergo LAG. The present results do not support the use of routine spirometry to stratify PPC risk in this surgical population. Patient age was identified as an independent predictor of PPCs, therefore there should be a higher expectation of PPCs in elderly patients ( ≥60 years) undergoing LAG, compared with a younger population. Implementing a programme of postoperative chest physiotherapy may help to prevent occurrence of more serious PPCs, in such cases.

Footnotes

Declaration of conflicting interest

The authors declare that there are no conflicts of interest.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

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Is routine preoperative spirometry necessary in elderly patients undergoing laparoscopy-assisted gastrectomy?

Abstract

Objectives

Methods

Results

Conclusions

Keywords

Introduction

Patients and methods

Study population

Surgical procedures and postoperative management

Spirometry

Definitions of outcomes and variables

Statistical analyses

Results

Discussion

Footnotes

Declaration of conflicting interest

Funding

References