Value of body plethysmography in preoperative assessment of thoracotomy candidates.

The usefulness of body plethysmography in the assessment of thoracotomy candidates is not well documented. Reported thresholds for operability are generally expressed in absolute values, which do not take into account a patient's size, age or gender. Spirometric and plethysmographic data of 103 patients undergoing thoracotomy were examined for their ability to predict death due to cardiopulmonary insufficiency, pneumonia, and atelectasis during the first 30 postoperative days. Neither plethysmographic nor spirometric parameters could predict atelectasis. Patients who underwent lobectomy were susceptible to the development of atelectasis. A weak correlation between elevated functional residual capacity (FRC) and occurrence of postoperative pneumonia was found. Lung function testing was not able to separate survivors from non-survivors. Patients with pneumonia were at high risk of death in their postoperative course. Because of the non-linear relationship, a correlation coefficient between spirometric and plethysmographic variables was not calculated. The prevalence of cardiac risk factors was high, so the decision for invasive hemodynamic studies should rather be based upon a patient's history than restricted to patients with impaired lung function. Because of methodological differences, and probably insuitable reference values, body plethysmography cannot substitute for spirometry. For FRC and FRC to total lung capacity (FRC/ TLC) ratio, further investigations must be undertaken to establish a correct reference value.