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Eur J Cardiothorac Surg 2006;29:202-209
© 2006 Elsevier Science NL

Prognostic value of chronic obstructive pulmonary disease in coronary artery bypass grafting

Rafael García Fuster * , José A. Montero Argudo, Oscar Gil Albarova, Fernando Hornero Sos, Sergio Cánovas López, María Bueno Codoñer, José A. Buendía Miñano, Ignacio Rodríguez Albarran

University General Hospital of Valencia, Valencia, Spain

Received 19 September 2005; received in revised form 19 September 2005; accepted 14 November 2005.

* Corresponding author. Address: C/Artes Gráficas no. 4, esc. izq. pta. 3, Valencia 46010, Spain. Tel.: +34 96 3622216; fax: +34 96 197 2163. (Email: rgfuster{at}terra.com).


   Abstract
Top
 Abstract
1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 Appendix A
 References
 
Objective: Coronary and chronic lung diseases have become a common association. This comorbidity has been generically considered by most of the operative risk scores, but its functional severity has seldom been addressed by these models. Our objective was to analyze its prognostic relevance considering preoperative pulmonary function parameters. Methods: All patients undergoing CABG from May 1993 to December 2004 have been reviewed. One thousand four hundred and twelve patients with preoperative pulmonary function test were finally included in the study. Obstructive lung disease was defined when FEV1/FVC < 0.7. In-hospital mortality and complication rate related to chronic obstructive pulmonary disease and its degree of severity (FEV1%) were assessed. Logistic regression analysis was used to determine independent predictors of mortality. Results: A pathologic preoperative pulmonary function test was found in 39% of patients: obstructive in 26% (FEV1/FVC < 0.7), restrictive in 9% and combined obstructive–restrictive in 4%. In-hospital mortality was higher in patients with abnormal test: 6.5% versus 0.9% (p < 0.001). Mortality was clearly related with the severity of lung disease: 0.9% in patients with FEV1: >80%, 0.4% in FEV1: 60–80%, 10.8% in FEV1: 40–59% and 54% in FEV1: <40%. In the latter group, other intercurrent prognostic factors were observed. Patients with FEV1 < 60% had higher mortality than those with FEV1 > 60%: 24.6% versus 1.4% (p < 0.001). Chronic obstructive lung disease was not an independent predictor of mortality but FEV1 ≤ 60% was significantly associated with death. Conclusions: This study on chronic lung comorbidity in CABG patients shows that this association can be of deleterious prognostic value but this effect is directly related to the degree of functional severity. Preoperative FEV1 < 60% must be considered as a primary prognostic factor in patients undergoing CABG procedures.

Key Words: Chronic obstructive pulmonary disease • Coronary artery bypass grafting • In-hospital mortality


   1. Introduction
Top
 Abstract
 1. Introduction
2. Materials and methods
 3. Results
 4. Discussion
 Appendix A
 References
 
Chronic obstructive pulmonary disease (COPD) has been identified as an important preoperative risk factor for morbimortality in patients undergoing CABG [1,2]. This comorbidity has been generically considered by most of the operative risk scores, but its functional severity has seldom been addressed by these models [3].

The influence of COPD in patients undergoing cardiac surgery is especially problematic because of the additional and combined deleterious effect of cardiopulmonary bypass (CPB) and sternotomy [4]. Both factors influence negatively the perioperative course of these patients, particularly with respect to postoperative pulmonary complications. Previously, significant pulmonary disease was considered a surgical contraindication. Nowadays, as a result of improvements in surgical techniques, anesthesia and postoperative management, COPD in patients undergoing CABG has become acceptable and a common association.

The aim of our study was to analyze the prognostic relevance of COPD and its severity considering the pulmonary function tests performed preoperatively in our patients undergoing CABG.


   2. Materials and methods
Top
 Abstract
 1. Introduction
 2. Materials and methods
3. Results
 4. Discussion
 Appendix A
 References
 
2.1 Patient study group
Between May 1993 and December 2004, 2236 consecutive patients underwent isolated CABG in our institution. They were identified through a prospectively maintained surgical database and medical charts were reviewed retrospectively in order to confirm information and complete missing data of interest. Only those patients with available preoperative pulmonary function test have been finally included in the study. Exclusion criteria were significant valve disease, emergent operations, other approaches than median sternotomy and other surgical procedures than CABG. Medical records were reviewed, including demographics, preoperative clinical data, pulmonary function testing results, cardiac catheterization hemodynamics, operative and postoperative data.

2.2 Pulmonary function testing and COPD diagnosis
COPD is characterized by airflow limitation and its diagnosis is confirmed with espirometry. Assessment of the severity of the preoperative pulmonary dysfunction is also performed using espirometry.

In our patients, COPD was defined when a compatible clinical picture was observed, when there was a chronic obstruction to the airflow and when other conditions with similar symptoms were ruled out. Obstruction to the airflow was confirmed with espirometry when the postbronchodilator FEV1/FVC was <0.7. A restrictive disease was diagnosed when FEV1/FVC was >0.85 in conjunction with other espirometric characteristics (Table 1 ).


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  		Table 1. Functional pulmonary disorders: espirometric patterns and functional severity
 
COPD represents a broad spectrum of lung diseases often difficult to define. For the purpose of our study, chronic bronchitis was defined clinically as chronic productive cough for 3 months in each of two successive years in those patients in whom other causes of productive chronic cough had been excluded [5]. Emphysema was defined pathologically as the presence of permanent enlargement of the airspaces distal to the terminal bronchioles, accompanied by destruction of their walls and without obvious fibrosis [6]. In patients with COPD either of these conditions may be present. However, the relative contribution of each to the disease process is often difficult to discern. On the contrary, asthma differs from COPD in its pathogenic and therapeutic response, and therefore it was considered a different clinical entity [7]. However, some patients with asthma develop poorly reversible airflow limitation. These patients are indistinguishable from patients with COPD but for practical purposes are treated for asthma. Poorly reversible airflow limitation associated with bronchiectasis, cystic fibrosis and fibrosis due to tuberculosis was not included in the definition of COPD.

Preoperative pulmonary function testing was performed on a routine basis in most of our elective surgical patients. According to the functional espirometric data obtained in each patient three different patterns of pulmonary dysfunction were considered: obstructive (COPD patients), restrictive and combined obstructive–restrictive. Most of these functional data were included prospectively in a surgical database as percentage of predicted values and as qualitative variables according to the COPD severity classification used in our institution (Table 1). Thus, for comparative analysis, four groups of patients were established according to COPD severity: normal respiratory function and mild, moderate and severe dysfunction.

2.3 Operative technique
All surgical records were reviewed to determine the surgical procedure performed, the cardioplegic technique employed and cross-clamp and CPB times. Operations were performed by seven surgeons during this 12-year period. An isolated CABG procedure was performed in all patients. Standard anesthesia and surgical technique, extracorporeal circulation and myocardial protection methods were used. A subgroup of patients was operated on off-pump (OPCAB subgroup). A median sternotomy approach was used in all of these patients. CPB was installed through the ascending aorta and right atrial cannulation and it was performed with centrifugal or roller pumps and membrane oxygenation. Myocardial protection employed was intermittent cold blood cardioplegia. Most of the patients received both antegrade and retrograde cardioplegia and "hot-shot" (or reperfusion with warm blood cardioplegia). Lowest core temperature varied from 28 to 32 °C depending on individual surgeon's preference. Continuous retrograde perfusion of cold blood was maintained, if possible, during the ischemic period.

The patients were transferred to the Intensive Care Unit (ICU) immediately after the operation and received ventilator assistance and monitoring. Extubation was usually undertaken after an initial 8-h period when patient criteria were stable. In OPCAB subgroup, the goal for extubation was within 4 h of arrival in the ICU.

2.4 Definitions
Chronic renal failure (CRF) was defined as a serum creatinine ≥ 2 mg/dl. Previous stroke was defined as history of a central neurologic deficit persisting for more than 72 h. Diabetes was defined as a history of diabetes mellitus regardless of its duration or need for oral or insulin treatment. Urgent operation was considered when the surgical procedure was performed during the hospital stay of an acute clinical episode. Postoperative renal failure was defined as the increase in baseline creatinine value of greater than 2 mg/dl in the absence of end-stage renal failure on dialysis. Prolonged ventilation was considered as the need for respiratory support for more than 48 h. Low cardiac output syndrome was considered in the analysis when postoperative inotropic support was used for more than 24 h. Finally, in-hospital mortality was defined as death at any time before discharge from the hospital.

2.5 Statistical analysis
Statistical analysis was carried out with SPSS 10.0 for Windows. Continuous data are presented as mean ± SD if normally distributed or as median and interquartile ranges if skewed distributed. Nominal data are presented as frequencies and percentages. The pulmonary function groups (four groups established according to the severity of the pulmonary dysfunction) were compared using {chi} 2-test for categorical variables and ANOVA test for continuous variables. Kruskal–Wallis test was used when the distribution of the groups was not normal. Several preoperative and intraoperative variables were investigated for association with hospital death at univariate analysis using the following statistical tests. Associations among nominal variables were compared by Pearson's {chi} 2-test, continuity correction or two-sided Fisher's exact test as appropriate. Continuous variables were compared by unpaired t-test. Mann–Whitney test was used to compare not normally distributed data. All variables with a p value of less than 0.10 at univariate analysis were entered in a subsequent multivariate analysis. Some other clinically relevant variables were also considered. Stepwise logistic regression models were used to determine independent predictors of in-hospital mortality with a selection cutoff set at 0.05. Models fit was evaluated using the Hosmer and Lemeshow goodness-of-fit statistic and residual analysis. Odds ratios, 95% confidence intervals (95% CI) and p values were reported. Area under the receiver-operating characteristic (ROC) curve (or C-statistic) was calculated as a measure of predictive power. A p value less than 0.05 was considered statistically significant.


   3. Results
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
4. Discussion
 Appendix A
 References
 
3.1 Patient characteristics
The patients enrolled in this study represent a typical referral practice for CABG in our country. They were predominantly male (82%) with a mean age of 63 ± 9 years. Thirty-six percent were diabetic, smoking status was present in 57%. Fifty and fifty-five percent of patients had hypertension and hypercholesterolemia, respectively. The mean EF was 55 ± 12% with 23% of patients having an EF of less than 50%. Patients mostly had triple vessel disease (75%) and 22% had a significant left main stem disease. Forty-five percent of patients were in CSS angina functional class III or IV and only 17% were in NYHA classes III–IV.

A global group of 1412 patients was evaluated by preoperative pulmonary function testing and was finally included in the study. An abnormal espirometry was observed in 550 patients (39%). Three hundred and sixty-eight patients had an obstructive spirometric pattern, 127 had a restrictive disease and 55 had a combined obstructive–restrictive pulmonary dysfunction. Patients with obstructive disease were included in a four-group classification according to their functional severity: normal respiratory function and mild, moderate and severe dysfunction. Preoperative patient characteristics and operative variables in these groups are shown in Table 2 (patients with restrictive and combined pulmonary dysfunction were not considered). Group 3 (moderate) and, particularly, group 4 (severe dysfunction) were more symptomatic and had a higher risk profile: lower EF, more frequent previous acute myocardial infarction and a higher prevalence of CRF, peripheral vascular disease, left main stem disease and urgent operation. This trend of increasing risk from group 1 to group 4 was reflected by euroSCORE.


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  		Table 2. Patient characteristics and operative variables
 
3.2 Patient outcomes
Out of 1412 CABG procedures performed, there were 44 perioperative deaths (3.1% mortality rate). Thirty-six patients with abnormal espirometry died in comparison with eight patients with normal test (6.5% vs 0.9% mortality, p < 0.001). This mortality was higher in patients with obstructive disease: 7.9%, 3.9% and 3.6% mortality rates for obstructive, restrictive and combined pulmonary dysfunctions, respectively. Causes of death in patients with COPD and in those with normal espirometry are detailed in Table 3 . A relative influence of age and sex on the mortality in patients with COPD was observed. Patients with age more than 75 years doubled the mortality rate: 13.3% versus 7.1%. Females had also a higher rate of mortality: 10.3% versus 7%.


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  		Table 3. Causes of death
 
One hundred and thirty-three patients were operated on by means of off-pump technique. In our study, mortality was higher in OPCAB patients because this technique was selectively used in high-risk patients: 6.8% versus 2.7% in the global group. In contrast, in patients with COPD mortality was similar: 8.3% versus 7.8%.

Increasing incidence of mortality was observed in patient groups of severity in obstructive and restrictive diseases (Fig. 1 ). When FEV1 = 60% was considered as a cutoff point, patients with FEV1 < 60% had a significantly higher mortality rate than patients with FEV1 ≥ 60% (restrictive and combined diseases included): 24.6% versus 1.4%, p < 0.001 (Fig. 2 ).


Figure 1
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  		Fig. 1. Increasing incidence of mortality in severity groups: (a) in obstructive disease patients and (b) in restrictive disease patients.

 

Figure 2
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  		Fig. 2. Mortality rate in patients with and without FEV1 < 60%.

 
Forty patients required prolonged ventilation (2.8%) and in 19 patients reintubation was needed in the postoperative period (1.3%). The overall median length of hospitalization was 9 days with a range of 5–61 days. In the whole cohort, the incidence of perioperative myocardial infarction was 0.8% and permanent stroke 1.7%.

Details of surgical outcomes according to functional severity groups are illustrated in Table 4 . Pneumonia and sepsis were particularly more frequent in moderate–severe COPD patients (18% and 11%, respectively) with higher rates of prolonged ventilation and reintubation. Prolonged ventilation was associated with a high mortality rate, especially in patients with COPD: 41% versus 26% in patients with and without COPD. A similar increase in mortality was observed with pneumonia: 31% versus 18%. Other extrapulmonary complications had also a higher incidence in these patients, particularly in group 4. These latter patients can be considered as an extremely high-risk group.


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  		Table 4. Postoperative variables
 
3.3 Predictors of death
Preoperative patient characteristics and intraoperative variables were evaluated univariately as predictors of in-hospital death. Statistically significant univariate associations to mortality and independent predictors of mortality identified from a subsequent multivariate logistic model are presented in Table 5 . The strongest univariate predictor of death was preoperative FEV1 < 60% (or moderate–severe COPD) and the lower significant predictor was left main stem disease. COPD as a categorical variable was also a significant predictor of death in univariate analysis. The logistic regression model for predicting in-hospital mortality showed that the most powerful predictors of death corresponded to preoperative comorbidities: FEV1 < 60%, CRF and peripheral vasculopathy. NYHA functional class was also a significant variable. Interestingly, FEV1 < 60% was retained in the final model but COPD was excluded. Model fit was adequate (Hosmer and Lemeshow test: {chi} 2 = 4.20, df = 7, p = 0.75) with an excellent predictive power with an area under the ROC curve of 0.92 (95% CI: 0.87–0.97).


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  		Table 5. Predictors of in-hospital mortality in univariate and multivariate analyses in the whole cohort
 

   4. Discussion
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
Appendix A
 References
 
Given the well-known role that tobacco plays in the development of COPD and the higher risk to suffer coronary artery disease by smokers, the association between these two entities is clinically frequent. Estimates of the prevalence of COPD depend on the definition and criteria used. COPD represents a broad spectrum of lung diseases often difficult to define [5]. Estimates based on the presence of airflow limitation are the most accurate, since symptoms and self-report or clinician diagnosis lack sensitivity and specificity. A postbronchodilator FEV1/FVC < 0.7, in combination with a FEV1 < 80% of predicted value, in an individual with cough, sputum production or dyspnea and exposure to risk factors confirms the diagnosis [7]. In the NHANES III study, less than 50% of individuals with COPD based on airflow limitation have a doctor's diagnosis of COPD and, somewhat surprisingly, this was not only true for mild COPD [8,9]. The functional criteria for the diagnosis have been used in our study because it obviates, to a large extent, the problem raised by the use of clinical criteria or administrative data on the discharge form. With these last procedures, cases of COPD could be underdiagnosed in the presence of a severe disease such as coronary artery disease. In the present study, COPD was defined when the FEV1/FVC was <0.7 and the degree of severity was calculated according to FEV1% values (Table 1). Absolute FEV1 in liters has been used by other studies but FEV1 in percentage of predicted value is a more reliable parameter because it is adjusted to patient age and size.

CABG is a safe and effective surgical intervention that is performed successfully in a wide range of patients [2,10–12]. Patients undergoing this procedure are changing to a increasingly higher risk profile than in the past: elderly patients with comorbid medical conditions. In recent years, "cardiac" variables as left main stem disease and angina class (important risk factors in CASS study) have lost their predictive value of mortality, in favor of new "extracardiac" factors as peripheral vasculopathy, CRF or COPD [13–15]. Thirty-nine percent of our patients had an abnormal espirometry and 67% of them had a pure obstructive pulmonary disease. The impact of COPD in patients undergoing general surgery and thoracic surgery is well known [2]. Actually, surgery is one of the potential factors implicated in the episodic decompensations of this chronic disease. But the influence of COPD in patients undergoing open-heart surgery is especially problematic because of the additional influence of CPB and sternotomy [4]. It is well known that CPB interferes with pulmonary function. On one hand, CPB can induce adverse effects on the alveolar stability by activation of the complement cascade, sequestration of neutrophils in the pulmonary microvascular bed, releasing oxygen-derived free radicals and changing the composition of alveolar surfactant [4]. Atelectasis is one of the most important problems after CPB especially in the first 48 h postoperatively. On the other hand, the influence of a median sternotomy approach on pulmonary function has been clearly evaluated and it has been shown that the structural changes in the chest wall after median sternotomy are the cause of restrictive pulmonary dysfunction, which can be prolonged for weeks after the operation [16]. Lung injury becomes more prominent after surgery in COPD patients. Pulmonary variables returned to their preoperative levels in approximately 4 months in these patients. Thus, COPD has been established as an important risk factor for mortality in patients undergoing CABG. For instance, the Society of Thoracic Surgeons established this comorbidity as an operative risk factor. Several risk models have also considered COPD: Standard euroSCORE and Cleveland Clinic score have allotted COPD a value of 1 [3,17]. The Veterans Administration showed patients undergoing CABG with a FEV1 < 1.25 l to have significantly higher acute mortality rate [18]. But detailed quantitative analysis of the influence of COPD on patients undergoing CABG has not been done.

Depending on the severity of the pulmonary dysfunction, the morbimortality can be very high, almost prohibitive in some patients. Therefore, a correct diagnosis of COPD and its severity is mandatory because it could allow better planning of resource allocation and guide some preventive strategies [1,2]. In these high-risk patients (group 4 in our study), it would be imperative to institute vigorous preoperative measures to improve the respiratory status before taking into account a surgical indication. So, COPD and other comorbid conditions must be considered in a quantitative way by risk models and not as categorical variables. The severity degree of these risk factors has an important prognostic relevance and not the factor itself. Actually, mild COPD is well tolerated by CABG patients in comparison with moderate or severe COPD. In our opinion, FEV1 must be the reference variable when COPD is included in a risk model. In this way, CRF is usually managed by risk scores considering preoperative creatinine levels (e.g., euroSCORE). Moreover, it would be preferable to keep continuous risk factors as continuous, rather than to discard information by collapsing them into groups, as the effect of these factors on the outcome usually varies smoothly rather than in jumps.

Morbidity due to COPD usually increases with age and it is still greater in males than in females [8]. CABG mortality was doubled in our patients with COPD and age more than 75 years: 13% in comparison to 7% in those with age less than 75 years. On the contrary, CABG mortality was higher in females with COPD (10% vs 7%).

Adverse respiratory system events such as respiratory failure and pneumonia have been traditionally the leading cause of postoperative complications [19]. Particularly, COPD patients are at an increased risk for lower respiratory tract infections because the immune suppressing effects of CPB combined with the respiratory flora of these patients. The development of pneumonia following CABG in patients with COPD was associated with 27% mortality as demonstrated by Gaynes et al. [20]. Thirty-two of our patients with COPD (8.6%) had a postoperative pneumonia with a mortality rate of 31.2%. But these results were even more negative in severe COPD groups, 18% of our patients with moderate–severe COPD (21/114) had a postoperative pneumonia with a mortality rate as high as 56%. Sepsis and multiorgan failure are usually the result of the outcome in these patients. Moreover, prolonged mechanical ventilation is known to result in increased ICU length of stay, decreased hospital bed availability, increased resource utilization and healthcare cost [10,11]. The fact that COPD patients are at risk of prolonged ventilation and reintubation was well observed in our study. The incidence of prolonged ventilation and reintubation was very high in group 4 and it was associated with a high rate of mortality. In addition, the need for tracheostomy postoperatively is higher in patients with preexisting pulmonary dysfunction and it is also associated with a significant mortality.

Supraventricular tachyarrhythmias are common after CABG in COPD. In our experience, the incidence of atrial fibrillation after CABG was low (around 13%) and its frequency was not higher in patients with significant COPD. Early prophylactic amiodarone in COPD reduces significantly supraventricular tachyarrhythmias [21]. A liberal use of this drug in our patients may be the reason of our results.

The optimization of management in the preoperative, perioperative and postoperative periods may be the key to reduce the negative outcomes in this high-risk group [2]. It would be important to improve the preoperative respiratory status of these patients by means of good adjustment of bronchodilator therapy and strict control by a physiotherapist. The correct timing of surgery is also mandatory in order to elude respiratory decompensation phases. A broader-spectrum antibiotic coverage, particularly Gram-negative, may play an important role, since it is well known that patients with COPD are colonized with a variety of organisms.

Nowadays, there is not enough evidence to support the conclusion that OPCAB is the best CABG method in patients with COPD. Recently, it has been postulated that myocardial revascularization with or without CPB causes a similar degree of pulmonary dysfunction, and the deterioration in pulmonary gas exchange associated with cardiac operation conceivably is due to factors other than the use of CPB [22]. On the contrary, Güler et al. [4] observed that FEV1 obtained in the second postoperative month was significantly lower than preoperative values only in the group who were operated on with the use of CPB. They suggested that off-pump procedures are more advantageous than on-pump methods for patients with COPD. Staton et al. [23] have demonstrated a greater decrease in postoperative respiratory static compliance in the OPCAB patients and this fact appears to be due to the need to rotate the heart into the right chest to allow bypass to posterolateral vessels and the large amounts of intravenous fluids required to maintain systemic blood pressure during the operation. In our experience, we have not evidenced a significant benefit avoiding CPB in COPD patients. However, OPCAB has been selectively indicated in a high-risk subgroup, so selection bias invalidates a direct comparison of both techniques in our study.

A fast-track protocol may be a valid option in the perioperative management of these patients. Criteria for extubation must be modified; the clinical assessment of the patient is an important factor rather than arterial blood gas analysis and conventional weaning parameters. This change may enable an early extubation with satisfactory results but reintubation risk must be considered.

Finally, it has been suggested that routine espirometry is probably unnecessary for most adult cardiac patients [24,25] but, in our opinion, this diagnostic test must be used more frequently in patients undergoing CABG.

In conclusion, COPD is an important risk factor in CABG. Our study shows that this comorbidity has a deleterious effect on postoperative outcomes, but its prognostic value is directly related to the degree of functional severity. Hospital morbimortality in most patients with mild-to-moderate COPD undergoing CABG is similar to those without COPD. But in a subgroup of patients with severe disease in-hospital mortality is exceptionally high. In these patients, it is imperative to provide appropriate preoperative, intraoperative and postoperative care if surgical indication is considered. Preoperative FEV1 < 60% must be established as a major prognostic factor in CABG risk models.

4.1 Limitations of the study
A number of limitations are inherent to this analysis design: a retrospective single institution study. A retrospective analysis is susceptible to various sources of bias, which may have not been identified and controlled. But given the relatively large cohort evaluated (n = 1412), the C-statistic of the multiple logistic regression model predicting a good-fit and the representativeness of the cohort, it is unlikely that our results are inaccurate or biased.

Another limitation of the present study is the long time period of the analysis (12 years); changes in surgical techniques and intraoperative myocardial protection methods along time may influence outcome and prognostic factors.


   Appendix A
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 Appendix A
References
 
Conference discussion

Dr J. Roquette (Lisbon, Portugal): You didn’t consider the opening of the pleural space as a factor while retrieving the internal mammary artery?

Dr Garcia-Fuster : Yes, I think it could be a good practice, but we have not considered in our analysis this variable. Perhaps it's a good practice in these patients, of course.

Dr C. Muneretto (Brescia, Italy): In your results you showed a very high mortality, up to 57% mortality in a group of high-risk patients. This could not be accepted by many surgeons, could you please comment on that?

Dr Garcia-Fuster : Yes, this is a very selected group of patients. Selection was performed with this parameter: FEV1 less than 40%.

We have in this group, patients with many associated comorbidities, not only a severe chronic obstructive pulmonary disease. Of course, this is a small group of patients, but I think this result is clinically quite impressive. And of course, this parameter of severe obstructive disease, FEV1 less than 40%, is an important parameter to assess this high risk.

I think that in these patients the risk can be improved if we do some improvements in our clinical practice. Of course, it is also important a correct indication of the operation. Perhaps some of these patients had formal contraindication for surgery.


   Footnotes
 
{star} Presented at the joint 19th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 13th Annual Meeting of the European Society of Thoracic Surgeons, Barcelona, Spain, September 25–28, 2005.


   References
Top
 Abstract
 1. Introduction
 2. Materials and methods
 3. Results
 4. Discussion
 Appendix A
 References
 

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S. R. Bapoje, J. F. Whitaker, T. Schulz, E. S. Chu, and R. K. Albert
Preoperative Evaluation of the Patient With Pulmonary Disease
Chest, November 1, 2007; 132(5): 1637 - 1645.
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