Physiology of Lung Resection

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vents and reverses hypoxia-induced pulmonary hypertension and pulmonaty vascular remodeling in Sprague- Dawley rats. J Cardiovasc Pharmacal 1997; 29:713-25 Olman MA, Can HZ, Yen HT, et al. Effects of chronic thromboembolism on the pulmona1y artery pressure-flow relationship in dogs. J Appl Physiol 1994; 76 :875-81 Janicki JS , Weber KT, Likoff MJ, et !a. The pressure-flow response of the pulmona1y circulation in patients with hea1i fai lure and pulmonary vascular disease. Circulation 1985; 6:1270-78 Wagenvoort CA, 'vVagenvoort N. Heve rsibility of plexogenic pulmona1y mieriopathy followin g bandin g of the pulmona1y arte1y. J Thorac Cardiovasc Surg 1984; 87:876-86 shewski M, et al. A comparison Konstantinides S, Geibel A, Ol of surgical and medical therapy for atrial septal defect in adults. N Eng] J Med 199.5; 333:469-73 Himmelman HB , Stulbarg M, Kircher B, etal. Noninvasive evaluation of pulmona1y arte1y press ure during exercise by saline-enh anced dopple r echocardiography in chronic pulmonmy disease. Circulation 1989; 79:863-71

Physiology of Lung Resection No Rules, Just ... Rx A ttempting to clarifY what makes a lung cancer patient a high risk for resectional surgery has been a fruitful area of investigation and debate for over 40 years. Recently, the prediction of postoperative maximum oxygen consumption (V0 2 max) by Bolliger and associates, 1 confirming the previous work of Corris and colleagues, 2 has narrowed the focus considerably. The report of Nezu and coworkers in this issue of CHEST (see page 1511 ) nicely confirms the effects of standard lobectomy and pneumonectomy on the cardiopulmonary function of relatively healthy lung cancer patients. Of particular interest is the small 13.3% reduction in V0 2 max secondary to lobectomy and the larger 28.1% decrement due to pneumonectomy. These results again suggest a significant contribution of lung function to exercise V0 2 max. However, these workers also found a 17% decrease in stroke volume, a 22% reduction in cardiac output, and a 65% increase in pulmonary vascular resistance in a small, 10-patient subgroup that was studied hemodynamically. This leaves some unanswered questions as to just what the links in the chain of events are that lead to the reduction in V0 2 max secondary to lung resection. So where are we in predicting just who should and shouldn 't have lu ng resection for their cancer? In an attempt to answer this question, I ne tered into my handy-dandy computer statistics program the individual patient data points from 10 studies dating from 1984 1 ·3-11 that used quantitative lung scanning and/or exercise testing in preoperative evaluation. I 1438

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FEV1-ppo (%predicted) FIGURE l. Plot of data from ten selected studi es 1·3 -ll using lung scan prediction of ppo FEV, VS exercise vo2.

then posed the question : "Please compare the predicted postoperative (ppo) FEY 1 and the exercise vo2data in the identification of those patients who failed to survive standard lung resection." Figure 1 constitutes the answer I obtained . . . amess! Granted, this was not a pristine meta-analysis or even a "quasi-semi" facsimile of a meta-analysis. Nevertheless, it doesn't take a rocket scientist to see that there is no clear distinction between the results of these tests of survivors compared with nonsurvivors. What do I suggest? More studies? Of course. In the meantime, with extremely sophisticated surgical and physiologic testing techniques generally available, each practitioner must assess their institution's capabilities and forge ahead. For example, quantitative radionuclide scanning (or segment counting) is generally available to predict/estimate postoperative function. Cycle or treadmill ergom etric assessment of exercise vo2(or assessment using level walking vs stair climbing distance tests ) is possible. Some institutions have staff expert in video-assisted thoracoscopic surgery. Some can offer sophisticated pulmonary rehabilitation followed by lung volume reduction surgery and cancer resection combined.l 2 Othe rs may have superb external beam radiotherapy13 or state-of-the-art chemotherapy protocols. In shmt, myopinion is that the old rules of inoperability (eg , MW < 50% predicted, FEY 1 < 2.0 L, PaC0 2 > 45 mm Hg, Dco < 50% predicted, FEY1-ppo < 0.8 L, FEV1 -ppo < 40% predicted, etc, etc) may no longer b e valid. In other words, do what you and your center do best. .. but treat the patient. Gerald N. Olsen, MD Columbia, South Carolina

REFERENCES

1 Bolliger CT, Wyser C, Roser H , et l.a Lung scanning and exercise tes tin g for th e prediction of postoperative perforEditorials

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mance in lung resection candidates at increased risk for complications. Chest 1995; 108:341-48 Corris PA, Ellis DA, Hawkins T, et l.a Use of radionuclide scanning in the preoperative estimati on of pulmona1y fun ction after pneumonectomy. Thorax 1987; 42:285-91 Smith TP, Kinasewitz GT, Tucker VvY, et al. Exercise capacity as a predictor of post-thoracotomy morbidity. Am Rev Respir Dis 1984; 129:730-34 Bechard D , Wetstein L. Assessment of exercise o:>.ygen consumption as a preoperative criterion for lung resection. Ann Thorac Surg 1987; 44:344-49 Olsen GN , Weiman DS, Bolton JWR, et al. Submaximal invas ive exercise testing and quantitative lung scanning in the evaluation f or tolerance of lung resection . Chest 1989; 95: 267-73 Markos J, Mullian BP, Hillman DR, et la. Preoperative assess ment as a predictor of post-thoracotomy mortality and morbidity after lung resection . Am Rev Respir Dis 1989; 139:902-10 Boysen PC, Clark CA, Block AJ. G raded exe rcise testing and post-thoracotomy complications. J Cardiothorac Anesth 1990; 4:68-72 Morice RC, Peters EJ, Ryan MB, et la. Exercise testing in the evaluation of p atients at high risk of complications from lung resecti on. Chest 1992; 101:356-61 Nakagawa K, Nakahara K, Miyoshi S, et la. Oxygen transport during incremental exercise load as a predictor of operative risk in lung cancer patients. Chest 1992; 101:1369-75 Holden DA, Rice TW, Stelmach K, e t la. Exercise testing, 6-min walk, and stair climb in the evaluati on of patients a t high risk for lung resection. Chest 1992; 102:1774-79 Pierce RJ, Copland JM , Sharpe K, e t la. Preoperative risk evaluation for lung cancer resection: predicted postoperative product as a predictor of surgical mortality. Am J Respir Crit Care Med 1994; 150:947-55 McKen na RJ, Fischel RJ, Brenner M , et al. Combined operati ons fo r lung volume reducti on surge ry and lung cancer. Ches t 1996; 110:885-88 Gauden S, Ramsay J, Tripcony L. The cu rative treatment by radioth erapy a ol ne of stage I non-small cell carcinoma of the lung. Chest 1995; 108: 1278-82

Sherlock Holmes, Albrecht Durer, and Socrates The International Labour Office Radiographic Classification of Pneumoconioses Reassessed for Asbestosis

I t has been stated that "The interpretation of films

for pneumoconiosis requires profound knowledge and perspicacity and that the ideal interpreter is a happy blend of Sherlock Holmes, Albrecht Durer and Socrates."1 This u;o's knowledge and perspicacity would certainly be applicable to the standard tool for interpreting chest films for pneumoconioses, the International Labour Office (ILO) Classification of Pneumoconioses, last revised in 19802 and overdue

for revision. The major advances in this scheme have been the inclusion of linear or "irregular" opacities to describe the interstitial fibrosis (IF) of asbestosis, increasing attention to pleural fibrosis (characterized as "thickening" and seen predominantly in asbestosexposed p ersons ), and refinement of the quantitative scale for profusion (number) of opacities from 4 points to 12. A number of investigations in the last decade using the varied disciplines of high resolution computerized tomography (HRCT), pulmonmy physiology, and analysis of mortality have provided n ew p erspectives on the correlation of the ILO readings (most importantly, the profusion score for irregular opacities, hereafter called "score") with other measures of the impact of asbestos-related pleuropulmonary fibrosis on the lung and on the patient. The study by Oksa and colleagues in this issue of CHEST (see page 1517) provides an opportunity to evaluate this information. Since 1930, successive revisions have altered the standardized scheme for interpreting chest films for pneumoconioses. Several basic investigations correlated workplace dust exposure, lung dust burden, and/or tissue response with the profusion score then in use, generally the 4-point score. The assumption was that "the more fibrosis present, the more retained dust"3 in the lung. These investigations were directed at coal workers' pneumoconiosis (reviewed by Fernie and Buckley" and Vallyathan and colleagues5) and to a l esser extent, at silicosis 6 -8 and asbestosis. 9 · 10 Indeed, asbestosis is different from the nodular pneumoconioses in its less consistent relationship of dust burden to histologic severity, and in the greater impact of its "irregular" IF on lung function. That radiographic abnormality carries with it a far greater effect on lung function in asbestosis than in the nodular pneumoconioses was recognized early in the history of asbestosis_9,1° In coal workers' pneumoconiosis and silicosis, the amount of dust and the severity of histologic fibrosis parallel each other.l 1·12 In addition, investigations have demonstrated consistent correlations between mineral content on the one hand,12 and the number and character of dust foci and fibrotic lesions on the other,13 with radiographic score. Eighty-five percent of the lungs in radiographic category 1 (scores 1/0, 1/1, and 1/2) showed only sparse dust foci unassociated with fibrosis.I 3 Prevalence of radiographic asbestosis (defined as scores 2':: 1/0) is proportionate to cumulative exposure to asbestos, the slope of the relationship varying from industry to industry.l 4 In general, the severity of histologic IF is related to the fiber burden in the lung. 1s-ts Kipen and colleagues, 19 in a 1987 study of heavily exposed insulators with lung cancer, noted CHEST I 113 I 6 I JUNE, 1998

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