Risk assessment of patients before lung surgery

Abstract

Lung resection offers the best prospect of long-term survival in patients with nonmetastatic pulmonary neoplasia. In view of the dismal prognosis of unresected bronchial cancer, surgical resection should be encouraged even in patients with reduced cardiopulmonary function. Accurate estimation of the postoperative cardiopulmonary function is therefore desirable to avoid (a) refusal of potentially curative treatment and (b) severe postoperative disability. The origins of post-resection morbidity and mortality are multifactorial. Thus, no single pulmonary function test or hemodynamic measurement can accurately and reliably predict postoperative cardiorespiratory complications. Criteria of functional operability should be based on percent of predicted value, so that patient's age, sex, and height will be taken into consideration. Exercise testing offers the advantage that both pulmonary and cardiac risk can be evaluated simultaneously. The high predictive value of maximal oxygen uptake (VO2max) in assessing postoperative morbidity and mortality is established. The calculation of predicted postoperative lung function (ppo) is of importance. The postoperative values for the forced expiratory volume in one second (FEV1-ppo), the transfer factor (TL,CO-ppo), and VO2max-ppo can be predicted by using the same formula. Patients with nearly normal lung function (FEV1, TL,CO > 75% predicted) and no concomitant cardiac disease can undergo lung resection right up to pneumonectomy without further diagnostic procedures. In the others, FEV1-ppo and TL,CO-ppo should be estimated first by taking into account the number of segments to be resected. Patients with values < 30% predicted are usually regarded as being inoperable, whereas values > 40% predicted qualify for resection without the need for further diagnostics. VO2max < 10 ml/kg/min or < 40% predicted are prohibitive for surgery. If VO2max is > 20 ml/kg/min or > 75% predicted, functional operability without limitation is given. For those cases where diagnostic uncertainty still remains, FEV1-ppo, TL,CO-ppo, and VO2max-ppo can be calculated by means of quantitative lung scans. Patients with either FEV1-ppo and TL,CO-ppo < 30% predicted or VO2max-ppo < 8 ml/kg/min or < 35% predicted are deemed inoperable.