What keeps postpulmonary resection patients in hospital ?

This study was presented at the American College of Chest Physicians 2001 Annual Meeting, November 4 to 8, 2001, Philadelphia, Pennsylvania, USA Department of Surgery, Queen’s University, Kingston, Ontario Correspondence: Dr Dimiti Petsikas, Kingston General Hospital, Division of Cardiothoracic Surgery, 76 Stuart Street, Kingston, Ontario K7L 2V6. Telephone 613-548-2383, fax 613-549-2902, e-mail fargoc@post.queensu.ca T Bardell, D Petsikas. What keeps postpulmonary resection patients in hospital? Can Respir J 2003;10(2):86-89.

The mean postoperative length of stay (LOS) is usually reported to be between five and seven days for patients that have undergone pulmonary resection (1-3).In cases in which complications arise, hospital stays can be much longer, resulting in increased morbidity and cost.Considerable effort has been invested to determine factors that are predictive of morbidity following pulmonary resection.Research efforts have been primarily directed at predictors of pulmonary complications.Complications considered include prolonged ventilation, reintubation, hypoxemia, carbon dioxide retention, atelectasis and pneumonia.Spirometry, exercise oximetry, car-©2003 Pulsus Group Inc.All rights reserved
Studies that have looked at prolonged air leak (PAL) as a complication of pulmonary resection surgery typically define PAL as an air leak persisting for at least seven days (2,7,9).Because many patients do not have air leaks that last this long (or do not have air leaks at all), we believe that any air leak that lasts longer than three days should be considered a PAL.Furthermore, because mean LOSs are often reported to be seven days or less, any study that defines PAL as an air leak lasting longer than seven days is almost assured at the outset of finding PAL to be predictive of increased postoperative LOS.
In the present study, we sought to determine the effect of PAL (defined as longer than three days) on postoperative LOS; to compare PAL to nausea and vomiting, poor pain control and other causes of increased LOS; to assess the predictive value of patient characteristics and operative factors on both LOS and the occurrence of a PAL; and to determine the relationship between the time of thoracostomy tube removal and postoperative LOS.

Patients
A retrospective review of 100 charts was conducted for patients who underwent pneumonectomy, lobectomy, bilobectomy, bullectomy or wedge resection between January 1998 and April 2000 at Kingston General Hospital, Kingston, Ontario.The patients were selected randomly (by hospital patient identification number) from 178 patients during the above stated time period.Only records for patients who were older than 18 years of age and had undergone pulmonary resection were considered.

Data collection
Factors considered to be possible predictors of increased LOS are listed in Table 1.Postoperative factors considered were time of chest tube removal and reason for increased LOS as summarized on the discharge record.If this was not clearly specified, the reason for increased LOS (longer than three days) was inferred from the progress notes.The outcome measured was postoperative LOS.Mean LOS was determined, along with 95% CIs, for each variable.

Statistical analysis
Statistical calculations were performed using SPSS version 10 (SPSS Inc, USA).Student's t test was performed to determine the relationship between the above factors and LOS.Correlation functions were performed for LOS and duration of thoracostomy insertion, pulmonary function test results and number of packyears of smoking.To determine which factors were predictive of PALs, χ 2 analyses were performed.Linear regression was performed for factors deemed to be significant following correlation analysis.

Patient characteristics
Of the 100 pulmonary resection patients selected for review, 91 met the inclusion criteria for the study.The mean age of patients was 56.3±3.1 years (range 18 to 82 years), with 18 patients aged 70 years or older.Of the 91 included patients, 38 were women (42%) and 53 were men (58%).Ninety per cent had a history of cigarette smoking.The pathological diagnoses are listed in Table 2. Procedures included 12 pneumonectomies, 38 lobectomies and 39 wedge resections.Bullectomies were performed 10 times (four of which were performed by video-assisted thoracic surgery).

Factors contributing to increased LOS
The reasons for increased LOS are summarized in Table 3.The mean postoperative LOS for all patients was 6.4 days.Patients noted to have a PAL had a significantly increased LOS (9.4 versus 5.2 days, P<0.001).LOS was not influenced by the type of pulmonary resection performed (wedge resection, lobecto-    my, pneumonectomy, bilobectomy or bullectomy).Patients with a diagnosis of cancer had longer stays than those with benign disease (7.0 versus 5.1 days, P=0.021).Table 2 shows the mean LOS according to pathological diagnosis.Pneumothorax on postoperative chest radiograph, the occurrence of an air leak at any time during the stay and the need for reoperation were all factors predictive of increased LOS (Table 4).LOS was not influenced by smoking history, operative complications, body mass index or body surface area.A weak correlation between age and LOS was found (r=0.245,P=0.017).A strong correlation between the time of chest tube removal and LOS was found (r=0.903,P<0.0001).This correlation is stronger when pneumonectomy is excluded (r=0.937,P<0.0001).The postoperative LOS can be predicted by the equation y = 0.88x + 2.49, in which x is the day of chest tube removal (Figure 1).A carbon monoxide diffusion capacity of less than 80% was predictive of increased LOS (7.9 versus 5.8 days, P=0.03), but forced vital capacity (FVC), forced expiratory volume in 1 s (FEV 1 ), FEV 1 /FVC and total lung capacity were not.Women had a significantly longer stay following pulmonary resection than men (7.5 versus 5.6 days, P=0.037).

Factors predictive of PAL
Of the 27 patients noted to have an air leak on the third postoperative day or later, 14 were men and 13 were women.The average age was 59 years (range 18 to 82 years).Patient characteristics were similar in both groups (Table 5).Pneumothorax on chest radiograph and an FEV 1 less than 1.5 L/min were predictive of PAL (Table 6).

DISCUSSION
In the present study, air leaks lasting at least three days were found to be associated with increased LOS following pulmonary resection.Nausea and vomiting, poor pain control, and other possible reasons such as constipation, anxiety and depression were not related to increased stay.Correlation analysis demonstrated that when pneumonectomy is excluded, LOS can be linked to PAL by the equation y = 0.88x + 2.49.This result suggests that patients who have their chest tubes removed sooner are discharged sooner.Other investigators found that male sex, advanced age, pneumothorax on the first postoperative day and FEV 1 /FVC less than 60% were predictors of PALs, but these results were not reproduced here (2,3,10).In this study, the discovery of a pneumothorax on chest radiograph at any time during the hospital stay was found to be predictive of PALs, as was an FEV 1 of less than 1.5 L/min.These results concur with those previously reported.Our findings also concur with those of Abolhoda et al (2), in that a significant difference in the LOS was found for patients that had an air leak for longer than seven days.Rather than defining a PAL as any leak lasting longer than seven days, we chose a cut-off of three days.Many patients are discharged as early as two or three days after pulmonary resection.In defining a PAL to be any air leak longer than the median LOS, a statistically significant increase in LOS for patients with a PAL is the only plausible result.
Patients with benign disease had shorter LOSs than those with malignancies.This may reflect a lesser degree of sys-    temic illness in this subset of patients.Female sex was also found to be weakly associated with a longer stay.This finding has not been consistently observed in patients undergoing pulmonary resection.It has, however, been a well-described occurrence for patients undergoing coronary artery bypass surgery (11,12).The present study was also limited by small sample size, resulting in insufficient power to limit the possibility of falsenegative results.There are also the usual limitations of a retrospective review, such as incomplete charting.Despite these limitations, it is clear from the results that air leaks are an important cause of increased LOSs.This study has demonstrated that patients noted to have a PAL have a significantly increased LOS.Further evidence that a PAL causes an increased LOS was provided by the linear relationship demonstrated between the time of chest tube removal and LOS.It is important to note that chest tubes are left in place for prolonged fluid drainage, as well as for air leaks.In the present study, we did not differentiate between these reasons for leaving a chest tube in.Poor carbon monoxide diffusion capacity and poor FEV 1 were subsequently shown to be predictive for developing a PAL.
It has been established that an increased LOS is associated with increased morbidity and cost (13,14).Prevention of air leaks may translate to decreased morbidity and increased savings.Several techniques to prevent air leaks have been attempted.The use of fibrin glue and the application of bovine pericardial strips along staple lines have both been met with limited success (15,16).Two techniques that show promise are the use of a new synthetic absorbable sealant and a pleural tent in patients after upper lobectomy (17,18).While further studies are needed to confirm the effectiveness of these methods, they may be useful in preventing air leaks and decreasing LOSs, especially if used in the subset of patients with poor preoperative lung function.

CONCLUSIONS
We have shown that PALs are related to prolonged hospitalization after pulmonary resection.Prevention of this complication may result in decreased LOSs, decreased morbidity and decreased cost.

Length of stay following pulmonary resection Can
Respir J Vol 10 No 2 March 2003 87

TABLE 3 Reasons for prolonged stay postpulmonary resection
*Mean length of stay for those with the reason listed versus those without (Note: Some patients had extended stays for more than one reason)

TABLE 4 Postoperative complications and length of stay (LOS) postpulmonary resection
Relationship between time of chest tube removal (days) and length of stay (days) for all procedures excluding pneumonectomy

TABLE 6 Analysis of subpopulation with prolonged air leak (PAL)
*Percentage with PAL for those with the characteristic listed versus those without.FEV 1 Forced expiratory volume in 1 s; FVC Forced vital capacity; DLCO Carbon monoxide diffusion capacity