Ann Thorac Surg 1997;64:332-333
© 1997 The Society of Thoracic Surgeons
See also page 328.
DR LEWIS WETSTEIN (Freehold, NJ): This is a very provocative study. My colleagues and I have also been extremely interested in defining the predictors of postoperative morbidity/mortality after pulmonary resection. I am confused, however, with your data. Are you saying that none of the patients in groups 2, 3, and 4, desaturated? Or are you saying that in spite of poor preoperative standardized pulmonary function tests, they will do well if they do not desaturate?
DR NINAN: Our patients were divided into four high-risk groups using conventional criteria for selection for pulmonary resection. These groups were compared for outcome and it was found that of these, exercise desaturation was the best predictor of postpneumonectomy outcome. Of course there was overlap between the groups; that is, some patients who desaturated also had low FEV1 or low diffusing capacity of carbon monoxide.
DR WETSTEIN: I guess the main conclusion is that if you have terrible preoperative pulmonary function, ie, FEV1 of less than 0.8 or a maximum oxygen consumption less than 10 mm/kg/min, and you do not desaturate you will do well.
DR NINAN: No, it is not. This is a retrospective review and it makes no conclusion like that. The majority of the patients who desaturated did not have an FEV1 of less than 0.8. The majority of our patients did not have peak oxygen uptakes assessed, so the article makes no mention of comparison with maximum oxygen consumption. This study basically suggests that exercise desaturation is more predictive of postpneumonectomy outcome than spirometry. In addition, it reports a standardized exercise oximetry test that could be used in the future for other studies as well as in clinical practice.
DR DANIEL L. MILLER (Louisville, KY): I also find your data unclear. The one thing I have a concern about, with regard to your preoperative testing, is that your patients were on a stair stepper and their oxygen saturation was measured by a finger probe, which I believe is inaccurate. What we use at the University of Louisville is actually a temporal probe. So I think to make this more clear you need to go back and do things in a prospective manner using a forehead temporal probe.
Also, in our patients who desaturate, we put them through a pulmonary rehabilitation program of about 2 weeks to improve their diaphragmatic strength and so forth. Are you using these data at the University of Pittsburgh for pulmonary rehabilitation to help improve the status of these patients?
DR NINAN: Finger pulse oximetry has been standard practice in this and all previous reported exercise oximetry tests. I have seen no evidence that this method is inaccurate.
Our patients who have poor preoperative pulmonary function now undergo a pulmonary rehabilitation program.
DR HARVEY I. PASS (Bethesda, MD): I too applaud the efforts to find a simpler way to predict postresection outcome. However, I have a problem with your four groups. There is no idea in this abstract that you have stratified for variables like the New York Heart Association category. So we do not know whether the groups are comparable. I think a prospective analysis is called for by this, and I think this study introduces a new technique to try and do this simply. We cannot make true comparisons between the groups in a retrospective analysis, and I think its going to be interesting in the future to have it redone.
DR NINAN: I think you have pointed out a problem with all retrospective reviews of this nature. But we also have evidence from previous larger studies that exercise oximetry is predictive of postresection outcome. What needs to be determined is whether exercise oximetry or an index of airway obstruction like spirometry is more predictive of postresection outcome in the type of patients in whom we perform resection nowadays.
Ann. Thorac. Surg. 1997 64: 328-332.
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