Abstract
Postoperative pneumonia is a serious complication following pulmonary resection. Aspiration of oesophageal reflux contents is known to cause pulmonary complications in patients with a history of gastrectomy. In this study, we compared the incidence of postoperative pneumonia in patients with or without previous gastrectomy. A retrospective review was conducted of clinical charts for patients who underwent radical pulmonary resection for non-small cell lung cancer from January 2006 to December 2010. Pneumonia was diagnosed with chest computed tomography findings in all cases. A total of 333 patients underwent pulmonary resections during the study period. Twenty-seven patients (8.1%) had a history of gastrectomy. Eight patients (2.2%) had postoperative pneumonia. All eight patients who developed postoperative pneumonia did not have pneumonia before pulmonary resection. Of the aforementioned 27 patients, five (18.5%) developed pneumonia postoperatively, whereas only three of 325 patients who did not have a history of gastrectomy (0.9%) had pneumonia (P < 0.001). In multivariate analysis, a history of gastrectomy had the highest impact on the odds ratio (8.81) for postoperative pneumonia. A significantly higher incidence of postoperative pneumonia was found in patients with a history of gastrectomy. Prophylactic treatment, such as premedication with ranitidine, should be considered in those patients.
Keywords: Lung cancer, Complication, Pneumonia, Gastrectomy
INTRODUCTION
Lung cancer is the leading cause of cancer death worldwide. Surgical resection is the mainstay treatment for patients with early stage non-small cell lung cancer (NSCLC). Postoperative pulmonary and infectious complications following thoracic surgery are associated with high morbidity and mortality [1]. The incidence of pulmonary and infectious complications is associated with prolonged hospital stay and high in-hospital costs [2], therefore, postoperative pneumonia is a serious complication [3].
The reported incidence of postoperative pneumonia after lung resection ranges widely, mostly because of variations in measurement criteria and study design. Several clinical studies have reported risk factors for postoperative pneumonia after pulmonary resection [2–4]. For example, age, low body mass index, chronic obstructive pulmonary disease (COPD) and smoking status have been reported frequently.
Some clinical research related to anaesthesiology has revealed that aspiration plays an important role in the incidence of postoperative pneumonia [5]. Aspiration of gastric contents contributes to pulmonary complications [6]. Patients undergoing thoracotomy are therefore at a high risk of acid gastroesophageal reflux, which may lead to tracheal acid aspiration [7]. Gastroesophageal reflux is a common complication after gastrectomy [8]. Tracheal acid aspiration of oesophageal reflux contents is the most important risk factor for pulmonary complications in patients who underwent gastrectomy [9]. In patients with a history of gastrectomy, the risk of postoperative pneumonia after pulmonary resection is suspected to be high; however, this remains unknown. This study compared the incidence of postoperative pneumonia between patients with and without a previous gastrectomy.
PATIENTS AND METHODS
A retrospective review was conducted using clinical charts of patients who had undergone radical pulmonary resection for NSCLC at Kansai Medical University Hirakata Hospital, Japan, from January 2006 to December 2010. Clinical information about the following factors was collected: age, gender, body mass index, smoking status, pulmonary function test (FEV1/FVC), comorbidity of COPD, diabetes mellitus, ischaemic heart disease, chronic renal failure, preoperative chemotherapy, surgical procedure, operation time, blood loss and prophylactic antibiotic use during and after surgery.
Emergency surgeries and cases with comorbid respiratory or extra-respiratory infections were excluded from the study.
Procedures
For preoperative management, the protocol of prophylactic physiotherapy education, including pursed-lip breathing, abdominal breathing and training with incentive spirometry (Coach 2, Smiths Medical, Saint Paul, MN, USA), was routinely started in the outpatient clinic under the mentorship of the attending nurse at 2–4 weeks before surgery in all cases.
Pulmonary resections were usually performed under general anaesthesia combined with epidural anaesthesia. For cases in which the administration of epidural anaesthesia was difficult, intravenous analgesics were alternatively added combined with general anaesthesia. All patients were intubated with a double-lumen endobronchial tube and maintained with single-lung ventilation during the intrathoracic period of the surgical procedure. A nasogastric tube was inserted before surgery and withdrawn after tracheal extubation at the end of anaesthesia. Extubation of the tracheal tube generally occurred at ∼30 min after chest closure. Video-assisted mini-thoracotomy was the surgical approach used in all cases. Axillo-lateral mini-thoracotomy or posterolateral mini-thoracotomy with 4 to 8-cm skin incisions to facilitate a utility port were routinely performed with two additional ports, one for a camera and one for assistance. Diprivan was mainly used in the induction and maintenance of general anaesthesia; muscle relaxants were used, as appropriate, for maintenance. During and after surgery, patients were optimally treated for pain control with epidural analgesia. This treatment was usually continued for three postoperative days.
Drinking resumed after a clinical swallowing evaluation 4 h after entering the intensive care unit. Oral alimentation was started on the morning of postoperative day 1 in all patients. A regular programme of physiotherapy with an ultrasonic nebulizer four times a day was started on the day of the operation, and incentive spirometry was restarted the next day. Patients walked the next morning while an attending nurse monitored oxygen saturation using a finger oximeter. Oxygenation was discontinued when oxygen saturation recovered to >96% at rest or to preoperative levels. Chest drainage tubes were removed when the volume of fluid drained was <200 ml/day, the fluids were clear and no air leakage was observed (usually on postoperative day 2).
Diagnosis and management of postoperative pneumonia
The following indicators led to suspicion of pneumonia: temperature >38.0°C, chest X-ray findings of consolidation and an elevated white cell count (>12 × 109/l). Pneumonia was finally diagnosed via chest computed tomography (CT) findings in all cases. Sputum cultures were performed as necessary. Bronchoscopic resumption of sputum for bacterial colonization was not indispensable for pneumonia diagnosis and management. When CT findings combined with clinical observations confirmed pneumonia, broad spectrum antibiotics were immediately administered before colonization results were obtained. For prolonged pneumonia refractory to broad spectrum antibiotics, more restricted spectrum agents were selected based on the colonization results. Antibiotics administered for purposes other than antibiotic prophylaxis were recorded. During the study period, four different types of postoperative prophylactic antibiotics were used, and patients were categorized accordingly.
Data acquisition and statistical analysis
Medical records of patients were retrospectively evaluated and patient data were reviewed. Data were expressed as the mean number of or the numbers of patients. Student's t-tests were used for continuous data, and chi-squared tests were used for categorical data. The analysis of prophylactic antibiotic data was performed among the four aforementioned groups. A P-value of >0.05 was considered to indicate statistical significance. All tests were two-tailed. All univariate predictors with a P ≤ 0.2 in logistic regression analysis were included in a multivariate analysis to determine the incidence of postoperative pneumonia. All statistical analyses were performed using JMP software version 7.0.2 (SAS Institute, Inc., Cary, NC, USA).
RESULTS
A total of 333 patients [211 (63.4%) men and 122 (36.6%) women; mean age: 67 years] underwent pulmonary resections during the study period. Ninety-four patients (28.2%) had COPD, and 107 (32.1%) were current smokers. Eight patients (2.2%) had clinical evidence of postoperative pneumonia after pulmonary resection. Table 1 shows the backgrounds of the patients with or without postoperative pneumonia.
Table 1:
Backgrounds of patients without (w/o) or with (w/) postoperative pneumonia
| w/o pneumonia | w/ pneumonia | P-value | |
|---|---|---|---|
| Number of patients | 325 | 8 | |
| Age | 66 | 73 | 0.046 |
| Male/female | 205/120 | 6/2 | 0.49 |
| Body mass index | 22 | 19 | 0.0018 |
| Smoking status | 0.88 | ||
| Never | 108 | 2 | |
| Former | 113 | 3 | |
| Current | 104 | 3 | |
| Pulmonary function test | |||
| FEV1/FVC | 74 | 70 | 0.15 |
| Comorbidity | |||
| COPD | 91 | 3 | 0.56 |
| Diabetes mellitus | 77 | 3 | 0.37 |
| Ischaemic heart disease | 35 | 2 | 0.21 |
| Previous gastrectomy | 22 | 5 | <0.001 |
| Preoperative chemotherapy | 25 | 1 | 0.62 |
| Procedure of surgery | 0.15 | ||
| Wedge/segmentectomy | 99 | 4 | |
| Lobectomy/bilobectomy | 215 | 3 | |
| Pneumonectomy | 11 | 1 | |
| Operation time (min) | 241 | 298 | 0.083 |
| Blood loss (ml) | 114 | 112 | 0.97 |
| Prophylactic antibiotics | 0.80 | ||
Twenty-seven patients (8.1%) had a history of gastrectomy. Five of eight patients who had postoperative pneumonia after pulmonary resection had undergone previous gastrectomy. Table 2 shows the backgrounds of patients with or without a history of gastrectomy. Of 27 patients who had undergone previous gastrectomy, 5 (18.5%) developed postoperative pneumonia, whereas only three (0.9%) of 325 patients, who did not have a history of gastrectomy, developed pneumonia (P < 0.001). Table 3 shows the details of patients who had postoperative pneumonia and the extent of previous gastrectomy. Postoperative pneumonia in these six patients occurred during the early phase after pulmonary resection (postoperative days 3–9). All eight patients who developed postoperative pneumonia had never had pneumonia before pulmonary resection.
Table 2:
Backgrounds of patients without (w/o) or with (w/) previous gastrectomy
| w/o gastrectomy | w/ gastrectomy | P-value | |
|---|---|---|---|
| Number of patients | 306 | 27 | |
| Mean age | 66 | 72 | <0.001 |
| Male/female | 187/119 | 24/3 | 0.0041 |
| Body mass index | 23 | 20 | 0.0030 |
| Smoking status | 0.062 | ||
| Never | 104 | 6 | |
| Former | 101 | 15 | |
| Current | 101 | 6 | |
| Pulmonary function test | |||
| FEV1/FVC | 74 | 75 | 0.86 |
| Comorbidity | |||
| COPD | 87 | 7 | 0.78 |
| Diabetes mellitus | 71 | 9 | 0.24 |
| Ischaemic heart disease | 32 | 5 | 0.20 |
| Preoperative chemotherapy | 25 | 1 | 0.41 |
| Procedure of surgery | 0.99 | ||
| Wedge/segmentectomy | 95 | 8 | |
| Lobectomy/bilobectomy | 200 | 18 | |
| Pneumonectomy | 11 | 1 | |
| Operation time (min) | 240 | 261 | 0.25 |
| Postoperative pneumonia (%) | 3 | 5 | <0.001 |
Table 3:
Cases of patients with postoperative pneumonia
| Case | Age | Extent of gastrectomy | Procedure of pulmonary resection | Postoperative day of pneumonia |
|---|---|---|---|---|
| 1 | 73 | Distal 1/2 | RUL | 9 |
| 2 | 70 | NA | LUL | 5 |
| 3 | 66 | Distal 3/4 | LLL | 30 |
| 4 | 71 | Partial 1/4 | Lingular resection | 3 |
| 5 | 79 | Distal 2/3 | Rt-S8 resection | 8 |
| 6 | 67 | Distal 3/4 | Lt-pneumonectomy | 4 |
| 7 | 81 | NA | Wedge (LLL) | 5 |
| 8 | 76 | NA | Wedge (RUL) | 29 |
NA, not applicable.
During the study period, no perioperative death was observed in any patient, including those who had postoperative pneumonia.
To analyse the incidence of postoperative pneumonia, all univariate predictors with P ≤ 0.2 were included in the multivariate analysis: age, body mass index, previous gastrectomy and duration of surgery. Among these factors, history of gastrectomy had the highest impact on the odds ratio (8.81) for postoperative pneumonia (Table 4).
Table 4:
Multivariate analyses for postoperative pneumonia
| Odds ratio | 95% confidence interval | P-value | |
|---|---|---|---|
| Multivariate analysis | |||
| Age | 1.09 | 0.97–1.26 | 0.14 |
| Body mass index | 0.72 | 0.53–0.92 | 0.0089 |
| Operation time | 1.01 | 0.99–1.02 | 0.059 |
| Previous gastrectomy | 8.81 | 1.70–52.17 | 0.010 |
DISCUSSION
This study demonstrated a significantly higher incidence (18.5%) of postoperative pneumonia in patients with a history of gastrectomy, whereas the overall incidence of postoperative pneumonia was 2.2%. The reported incidence of postoperative pneumonia varies from 2 to 30% [3]. Our routine perioperative management of patients, such as prophylactic physiotherapy education in the outpatient clinic before admission [10], pain control with epidural anaesthesia during and after surgery and gastrointestinal management (including routine gastric tube insertion), may have affected the low incidence of postoperative pneumonia. Postoperative pneumonia occurred early in the postoperative period (Table 3); consistent with previous reports [3, 11]. The high incidence of postoperative pneumonia in patients with a history of gastrectomy is a significantly remarkable finding as this has not been previously recognized as a risk factor.
Many risk factors for postoperative pneumonia have been reported in retrospective and prospective studies, the most frequent of which are age, smoking status, cardiovascular comorbidity and COPD [3]. The univariate analysis in this study showed that age, body mass index and previous gastrectomy were statistically significant risk factors for postoperative pneumonia. To address the issue of confounding between previous gastrectomy and other factors, multivariate analysis including these three factors and duration of surgery (P = 0.090) was performed. The results were statistically significant only for body mass index and previous gastrectomy (odds ratio: 0.72 and 8.81, respectively). Being underweight has been identified as an important risk factor for postoperative complications such as pneumonia and prolonged air leakage [4]. Furthermore, our study showed that low body mass index was a significant risk factor for postoperative pneumonia (odds ratio: 0.72; P = 0.0089 in multivariate analysis).
Gastroesophageal reflux is a frequent incidental complication after gastric resection. The onset of gastroesophageal reflux after distal gastrectomy is induced by surgical procedures. In addition, hiatal hernia may be an important factor in the aetiology of reflux oesophagitis [12]. Furthermore, aspiration of gastric contents during anaesthesia is commonly recognized as a risk factor for pulmonary complications after lung resection [11]. Therefore, our finding in the risk factor analysis that the history of gastrectomy was the most important risk factor seems to be a reasonable finding in risk factor analysis, although it has not been reported before. In our research, all five patients who had postoperative pneumonia with a history of gastrectomy had never had pneumonia before the pulmonary resection. Thus, the lung resection itself in patients with previous gastrectomy may increase the incidence of aspiration and subsequent pneumonia.
Roberts et al. [6] reported that aspiration and subsequent respiratory failure and mortality can be decreased with pre-emptive gastrointestinal tract management. Inserting a nasogastric tube during surgery is necessary to prevent pulmonary complications and is routinely performed in clinical practice. Ranitidine premedication increases gastric pH and reduces gastric volume and acid gastroesophageal reflux [13]. Agnew et al. [7] demonstrated frequent incidences of both acid gastroesophageal reflux and tracheal acid aspiration during surgery that were significantly reduced by premedication with ranitidine. Premedication with an H2-receptor antagonist would also be effective for preventing postoperative pneumonia in patients with a history of gastrectomy. Targeted antibiotic prophylaxis may decrease the rate of postoperative pneumonia and improve the outcome after lung resection. Prophylactic regimens with cefazolin are ineffective against pulmonary infection [11, 14]. Some reports have demonstrated a relationship between postoperative pneumonia and perioperative colonization, but colonization results are not always consistent with pathogens of pneumonia [15]. Selecting antibiotics specific for preventing postoperative pneumonia and their duration of administration cannot be determined from previous reports.
In conclusion, a significantly higher incidence of postoperative pneumonia was demonstrated in patients with previous gastrectomy in this study. In those patients, ranitidine premedication and antibiotics with a spectrum broader than that of cefazolin should be considered for prevention of postoperative pneumonia.
ACKNOWLEDGEMENTS
We thank Tomoko Fuji for her data management and Yoko Oda for her assistance in this study.
Conflict of interest: none declared.
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