Lateral position test: a simple, inexpensive, yet accurate method of studying the separate functions of the lungs

Graded exercise testing and postthoracotomy complications

A controversy exists over whether or not preoperative exercise testing can predict postthoracotomy complications. This study was designed to evaluate the usefulness of a presurgical exercise protocol in patients with lung disease, but no evidence of cardiac disease. Seventy patients underwent baseline pulmonary function testing and split function perfusion studies, when indicated, to calculate predicted postoperative pulmonary function. Noninvasive data were incrementally collected from 17 patients by using a treadmill exercise tolerance test that was designed to elicit maximal performance. Inhaled and exhaled gas flow and volume, the partial pressure of O2 and CO2, maximal O2 consumption (VO2max), and maximal minute ventilation (VE max) were measured. The breathing and heart rate reserves were calculated by standard formulae in an attempt to separate cardiac from pulmonary exercise limitation. Two patients had postoperative cardiopulmonary complications after thoracotomy and lung resection, and six patients had noncardiopulmonary complications. There was no significant prognostic relationship among VO2max, VE max, maximum O2 pulse, and the incidence of postoperative cardiopulmonary complications. The percentages of predicted VE max and predicted maximum heart rate were related to the occurrence of total complications, but not specifically to cardiopulmonary complications. The results emphasize the difficulty in attempting to exercise thoracotomy candidates with chronic lung disease to maximal performance. Excluding patients from further surgical consideration because of exercise limitation is not feasible based on these data.

Lateral position test and quantitative lung scan in the preoperative evaluation for lung resection

The postpneumonectomy FEV1 was predicted in 24 patients with severe chronic obstructive pulmonary disease (FEV1 less than or equal to 2.0 L) and a lung mass using the quantitative lung scan (QLS) and lateral position test (LPT). Although a good correlation (r = .72, p = 0.0006) was found between the FEV1 predicted by QLS and LPT, there was more than 10 percent difference between the result in 59 percent of the subjects. A subgroup of these patients performed multiple (two to five) LPTs, and the results were calculated blindly to assess variability. The variation seen was 14 times greater than in previously reported normal subjects. Calculations suggest that as many as 37 tracings would be needed on each patient to obtain an acceptably low measurement error. Whereas there was a good overall correlation between the predicted postpneumonectomy FEV1 using both methods, the variability found with LPT would suggest extreme caution in its use.

Use of lateral position test and perfusion lung scan in predicting mediastinal metastases

The lateral position test (LPT) accurately measures differential ventilation of the lungs when the mediastinum is mobile. The quantitative perfusion lung scan (PLS) also correlates well with differential ventilation but is not dependent on mediastinal movement. If tumor metastasis to mediastinal lymph nodes (MLN) inhibits mediastinal movement, then the PLS may give discordant values for differential ventilation from that of the LPT. Before mediastinoscopy or thoracotomy or both, 14 cases of lung cancer were prospectively evaluated by comparing the relative ventilation of the involved lung as determined by LPT and PLS. Seven patients who had no evidence of MLN involvement had nearly equal ventilation by the two techniques (r = .94), and the absolute difference was always less than 12 percent (mean, 4.4 percent). Seven patients with MLN involvement had unequal ventilation as determined by LPT and PLS (r = 0.07), and between the two techniques there was a difference of at least 13 percent (mean, 27.3 percent). We conclude that the LPT used in combination with the PLS is an accurate, economical, and noninvasive technique for suggesting MLN metastasis and, thus, tentatively staging carcinoma of the lung. Those patients with discordant values should probably undergo mediastinoscopy before thoracotomy.

Prediction of postoperative pulmonary function with the lateral position test. A prospective study

Ten patients undergoing pneumonectomy were evaluated with the lateral position test (LPT) in addition to routine pulmonary function tests (PFTs). On the basis of the percentage of ventilation estimated to be contributed by each lung on LPT, predictions were made for expected values for each patient's post-pneumonectomy PFTs. One to three months after surgery patients were again evaluated with complete pulmonary function studies. Results were found to agree closely with preoperative predictions in most patients. We conclude that the easily performed LPT, previously found to yield values which correlate with those found on bronchospirometry and macroaggregate lung scanning, does indeed yield acceptable results clinically and is deserving of more widespread application, especially in the large number of institutions without nuclear medicine capabilities.

Unilateral lung function. Comparison of the lateral position test with radionuclide ventilation-perfusion studies

Twenty-seven patients underwent studies of unilateral lung function by the lateral-position test (LPT) and by computer-analyzed radionuclide imaging of ventilation and perfusion. The patients were divided into two groups, symmetric or asymmetric, on the basis of the physical examination of the chest and the chest radiograph. In patients with symmetry, the estimate of unilateral lung function by the LPT and isotopic estimates for unilateral lung volume, unilateral distribution of tidal volume, and unilateral perfusion, agreed within 2 percent, 4 percent, and 3 percent, respectively. In patients with asymmetry, the differences were 9 percent, 8 percent, and 13 percent. In settings of marked unilateral ventilation-perfusion imbalance, the LPT primarily reflected ventilation. Prediction of unilateral ventilatory function based upon the LPT and spirometric measurements agreed closely with unilateral ventilation determined isotopically by 133xenon, even in the presence of chronic obstructive lung disease. Our results confirm that the LPT provides valid information about unilateral lung function.