Functional evaluation before lung resection: searching for a low technology test in a safer environment for the patient: a pilot study

Objectives: Stair climbing is considered the first step for functional evaluation of patients requiring anatomical lung resection who have low-predicted postoperative forced expiratory volume in the first second of expiration (FEV1) or diffusing capacity of the lungs for carbon monoxide (DLCO) values. Nevertheless, stair climbing is not performed in many centres because of structural issues or patient safety concerns. We hypothesized that comparable exercise can be obtained on an ergometric bicycle in a safer environment where any adverse event can be treated. We tried to correlate the amount of exercise performed by stair climbing and by using an ergometric bicycle in a series of patients with non-small-cell lung cancer (NSCLC) evaluated prospectively.

Methods: Thirty-four consecutive patients with NSCLC who were scheduled for lung resection were prospectively enrolled to complete two low-technology exercise tests: The first one was stair climbing, and the second was a ramp test on an ergometric bicycle. For most patients (85%), both tests were performed on the same day, separated with at least 2 h of rest. The amount of exercise on the stair-climbing test (in watts: Watt 1) was calculated per patient weight, height reached on stairs and time spent. The bicycle test was performed on a Lode Corival ergometer with automatic calculation of the total work load (Watt 2). No estimation of VO 2 max was attempted. The bicycle test was conducted in an ad-hoc room fully equipped with oxygen, cardiac and blood pressure and PO 2 monitoring and resuscitation equipment. The Bland-Altman plot was used to evaluate the agreement between both tests. A linear regression model was constructed in which the power developed on the stairs was the dependent variable and the watts generated on the bicycle and patient age were the covariates.

Results: All patients (median age: 65.5 years; range: 41-84), completed both tests without any adverse events. The number of watts was greater on the stairs tests (mean 227 vs 64 on the ergometric bicycle). The Bland-Altman plot showed agreement between tests in most cases (Pitman-Morgan test: 0.96). Work load was more dependent on age in the stairs tests (Pearson coefficient -0.72 on stairs; -0.52 on ergometric bicycle). The logistic model was highly predictive when the workload on the bicycle was corrected by the patient's age ( R 2 = 0.80; Wald test <0.001).

Conclusions: This simple test on an ergometric bicycle shows a high correlation with the widely accepted stair-climbing test when workload results are corrected using the patient's age. It could replace the stair-climbing test and has the advantage of being conducted in an environment that is safer for the patient. Nevertheless, its reliability for risk prediction needs to be adequately evaluated.