Oxygen transport during incremental exercise load as a predictor of operative risk in lung cancer patients

Functional evaluation before lung resection

Advances in operative technique and perioperative care have reduced surgical morbidity and mortality considerably after pulmonary resections. Various single and combined parameters of functional operability have been proposed to assess the surgical risk. Patients with normal or only slightly impaired pulmonary function (FEV1 and DLCO > or = 80% predicted) and no cardiovascular risk factors can undergo pulmonary resections up to a pneumonectomy without further investigation. For others, exercise testing, pulmonary split-function studies, or a combination of these methods are recommended. Cardiopulmonary exercise testing, most frequently performed as a symptom-limited test with the measurement of VO2max, assesses the pulmonary and cardiovascular reserves. A VO2max of less than 10 mL/kg/minute generally is considered prohibitive for any resection, a value of greater than 20 mL/kg/minute or greater than 75% predicted normal, safe for major resections. Split-function studies are radionuclide-based estimations of the ppo values of various parameters. The currently used ppo parameters are FEV1-ppo, DLCO-ppo, and VO2max-ppo. Suggested cutoff values for safe resection are: FEV1-ppo and DLCO-ppo 40% or greater than predicted, and V(r)O2max-ppo 35% or greater than predicted, combined with an absolute value of greater than or equal to 10 mL/kg/minute. The lowest acceptable ppo values remain to be confirmed by additional prospective studies. Resections involving not more than one lobe usually lead to an early functional deficit followed by recovery. The permanent loss in pulmonary function is small (approximately 10%) and exercise capacity is reduced only slightly or not at all. Pneumonectomy leads to an early permanent loss of about 33% in pulmonary function and approximately 20% in exercise capacity. Pulmonary function tests alone therefore overestimate the functional loss after lung resection.

Symptom-limited stair climbing as a predictor of postoperative cardiopulmonary complications after high-risk surgery

STUDY OBJECTIVE

Thoracotomy, sternotomy, and upper abdominal laparotomy are associated with high rate of postoperative cardiopulmonary complications (POCs). We hypothesized that symptom-limited stair climbing predicts POCs after high-risk surgery.

DESIGN

A prospective evaluation of 83 patients undergoing thoracotomy, sternotomy, and upper abdominal laparotomy surgery.

METHODS

The 52 men and 31 women completed symptom-limited stair climbing. A separate investigator, blinded to the number of flights of stairs climbed, assessed 30-day actual outcomes for POCs, including pneumonia, atelectasis, mechanical ventilation for > 48 h, reintubation, myocardial infarction, congestive heart failure, arrhythmia, pulmonary embolus, and death within 30 days of surgery. The operations performed included 31 lobectomies, 6 wedge resections, 3 pneumonectomies, 3 substernal thymectomies, 1 substernal thyroidectomy, 23 colectomies, 3 laparotomies, 7 abdominal aortic aneurysm repairs, 5 esophagogastrectomies, and 1 nephrectomy.

RESULTS

POCs occurred in 21 of 83 patients (25%) overall, in 9 of 44 patients undergoing thoracotomy/sternotomy (20%), and in 12 of 39 patients undergoing upper abdominal laparotomy (31%). Of those unable to climb one flight of stairs, 89% developed a POC. No patient able to climb the maximum of seven flights of stairs had a POC. The inability to climb two flights of stairs was associated with a positive predictive value of 82% for the development of a POC. The number of days in the hospital postoperatively decreased with a patient's increased ability to climb stairs.

CONCLUSIONS

Symptom-limited stair climbing offers a simple, inexpensive means to predict POCs after high-risk surgery.

Cardiopulmonary exercise testing in the preoperative assessment for lung resection surgery

Whereas pulmonary function tests (PFTs) initially identify high-risk pulmonary patients being evaluated for lung resection surgery, other diagnostic modalities, including cardiopulmonary exercise testing (CPET) and/or split function studies, are then necessary for a more accurate assessment. CPET including VO2max have emerged as integral components of a step approach for the physiologic assessment for lung resection surgery. Increasingly, CPET is being used because it provides the best index of functional capacity and global O2 transport (VO2max) as well as estimating both cardiac and pulmonary reserves not available from other modalities. CPET permits the detection of clinically occult heart disease and provides a more reliable estimate of functional capacity postoperatively compared with PFTs, which routinely overestimate functional loss after lung resection. Currently, though split function studies are clearly established and have traditionally been used before CPET in preoperative decision analysis, recent work favors using CPET including VO2max before split function studies because VO2max % predicted is a good independent predictor of risk. Importantly, both studies are complementary and optimize assessment of surgical risk; this is particularly valuable for borderline patients, so that opportunity for curative resection is not denied.

Surgical management of early stage lung cancer

For patients with lung cancer, the greatest hope for cure rests with patients with early stage disease. Surgery has been the standard of care for this group with the best 5-year survival of only 65% being achieved in patients with earliest pathologic Stage IA disease. Using strategies gained from the management of patients with advanced disease, clinicians are investigating the use of perioperative chemotherapy and radiotherapy to improve survival. In addition, biologic and molecular markers are being evaluated to assist in predicting prognosis and to identify those patients at increased risk for recurrent disease. Postoperative surveillance of patients using helical computed tomography (CT) scanning is being investigated to detect early recurrences and second primary lesions. With such treatment and management plans on the horizon, the prognosis of patients with early stage non-small cell lung cancer (NSCLC) may be improved.

Prediction of hypoxemia and mechanical ventilation after lung resection for cancer

BACKGROUND

Hypoxemia usually occurs after thoracotomy, and respiratory failure represents a major complication.

METHODS

To define predictive factors of postoperative hypoxemia and mechanical ventilation (MV), we prospectively studied 48 patients who had undergone lung resection. Preoperative data included, age, lung volume, force expiratory volume in one second (FEV1), predictive postoperative FEV1 (FEV1ppo), blood gases, diffusing capacity, and number of resected subsegments.

RESULTS

On postoperative day 1 or 2, hypoxemia was assessed by measurement of PaO2 and alveolar-arterial oxygen tension difference (A-aDO2) in 35 nonventilated patients breathing room air. The other patients (5 lobectomies, 9 pneumonectomies) required MV for pulmonary or nonpulmonary complications. Using simple and multiple regression analysis, the best predictors of postoperative hypoxemia were FEV1ppo (r = 0.74, p < 0.001) in lobectomy and tidal volume (r = 0.67, p < 0.01) in pneumonectomy. Using discriminant analysis, FEV1ppo in lobectomy and tidal volume in pneumonectomy were also considered as the best predictive factors of MV for pulmonary complications.

CONCLUSIONS

These results suggest that the degree of chronic obstructive pulmonary disease in lobectomy and impairment of preoperative breathing pattern in pneumonectomy are the main factors of respiratory failure after lung resection.

An evaluation of integrated cardiopulmonary exercise testing in a pulmonary function laboratory

Clinical exercise testing has been used mainly to assess the cardiac response to exercise. Integrative cardiopulmonary exercise tests (CPET) involving the measurement of the ventilatory, circulatory and metabolic response to exercise has largely been a research tool. We analysed the results of one hundred tests randomly chosen from a total of 472 exercise tests performed between January 1992 and June 1993 as clinical investigation in a pulmonary function laboratory. CPET was used (a) to identify the cause of effort limitation in patients where more than one illness could be relevant (26); (b) to obtain an objective measure of the exercise capacity of patients with respiratory or cardiac disease (31); (c) as monitor of response to treatment (11) and (d) in the investigation of unexplained dyspnoea (32). In 94 of the 100 cases CPET was able to provide an answer to the specific clinical question posed. In patients with unexplained dyspnoea (CPET identified a group who exhibit an inappropriate hyperventilatory response to exercise with no supportive evidence of cardiopulmonary disease. In a small minority of cases CPET gave non-specific results. We conclude that CPET is a useful investigation in the management of patients with cardiopulmonary disease and complements the various other investigations offered by a pulmonary function laboratory.

Optimizing selection of patients for major lung resection

OBJECTIVES

It is not known whether a normal diffusing capacity for carbon monoxide permits safe lung resection in patients with marginal spirometric values, or whether normal spirometric values negate the adverse effects of a low diffusing capacity. The purposes of this study were (1) to determine the best predictors of morbidity and mortality and (2) to assess whether interactions exist between diffusing capacity and spirometry that help estimate outcome after major lung resection.

DESIGN

A retrospective analysis of 376 patients who underwent lung resection was performed. Three hundred three had lung cancer and 73 had other disease. Two hundred eighty-four underwent lobectomy/bilobectomy and 92 had pneumonectomy. We assessed the relationship of 23 preoperative variables to 18 postoperative events classified into categories as pulmonary or cardiac complications, overall morbidity, and operative mortality.

RESULTS

The best single predictor of complications was the percent predicted postoperative diffusing capacity. The incidences of pulmonary and cardiac complications, morbidity, and mortality were inversely related to predicted postoperative diffusing capacity percent (p < 0.004 for each). Multivariate logistic regression analyses identified only predicted postoperative diffusing capacity percent and age as significant independent predictors of pulmonary complications, morbidity, and death, and these with prior myocardial infarction predicted cardiac complications. There were no interactions between percent predicted postoperative forced expiratory volume in 1 second and predicted postoperative diffusing capacity percent in estimating risks of complications.

CONCLUSION

Predicted postoperative diffusing capacity percent is the strongest single predictor of risk of complications and mortality after lung resection. There is little interrelationship of predicted postoperative diffusing capacity percent and predicted postoperative forced expiratory volume in 1 second, indicating that these values should be assessed independently in estimating operative risk.

Routinely performed multigated blood pool imaging (MUGA) as a predictor of postoperative complications of lung resection. A two-year retrospective

The results of routinely performed multigated blood pool studies (MUGA) were compared with the presence of postthoracotomy complications in 46 adult men in a retrospective chart review. Pulmonary function measurements were also examined in relation to the presence of complications experienced. There was only one death, but survivable complications were not predicted by the MUGA results. The addition of MUGA as a routine preoperative cardiac screening technique did not result in increased ability to predict postoperative cardiopulmonary complications.

Pulmonary complications in patients undergoing thoracotomy for lung carcinoma

One hundred three consecutive patients undergoing 106 thoracotomies for primary lung carcinoma were reviewed to determine factors associated with the development of postoperative pulmonary complications. Pulmonary complications occurred in 40 of 104 (39 percent) patients. Minor complications occurred in 17 of 104 (16 percent) patients and major in 23 of 104 (22 percent). There were six deaths in the entire series of 103 patients (6 percent), two of which were directly caused by a pulmonary complication and one where it was a contributing factor. Extended surgical resections were associated with an increased risk of complications. Pulmonary complications occurred in 9 of 11 (82 percent) patients undergoing extended resections involving chest wall resection. The use of neoadjuvant chemotherapy also was associated with an increase in the rate of major complications. Poor nutritional status as measured by a history of weight loss and preoperative serum albumin levels also was associated with an increased risk of any pulmonary complication. Cardiac complications were significantly increased in the group of patients having pulmonary complications. Pulmonary complications continue to present a major source of morbidity and mortality for patients undergoing thoracotomy for lung carcinoma. Determination of factors associated with increased risk is important in order to identify patients who might be predisposed to the development of these complications.