PREOPERATIVE EVALUATION OF PULMONARY-FUNCTION - VALIDITY, INDICATIONS, AND BENEFITS

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Abstract
Alterations of pulmonary function are common after many types of surgery. These changes can proceed to postoperative pulmonary complications in some normal patients and in many patients who are at high risk because of nonpulmonary and pulmonary risk factors. The validity of preoperative evaluation of pulmonary function is based on the assumption that patients at risk of developing postoperative complications can be readily identified by screening pulmonary function studies, and that the institution of prophylactic measures in such patients decreases the incidence of postoperative complications. History, physical examination, chest roentgenography and ECG provide the initial means of identifying each patient group. The optimal way of evaluating these patients preoperatively is by clinical spirometry and arterial blood gas analysis. Clinical spirometry fulfills each of the criteria of an ideal screening test; spirometric abnormalities correlate with postoperative complications. Patients who are identified as having marginal function by these screening tests should be studied further by more specialized studies, including radioisotopic evaluation of regional lung function. The use of preoperative evaluation of pulmonary function presents a different magnitude of problem in defining the risk of morbidity in contrast to that of mortality. Available data provide a firm basis for the identification of the patient at increased risk of morbidity. After 23 yr and dozens of spirometric studies involving thousands of patients, there apparently is no spirometric number, percentage or category that will absolutely separate the operable from the inoperable patient. These areestimates of risk, guidelines to be sure, but no absolutes. The patient whose lung function would be considered to prohibit lung resection in the 1950s was successfully operated on in the 1970s. In dealing with the risk of mortality, the physician should always bear in mind that, although statistics apply to groups, they often do not apply to individual patients.