Introduction
Exercise intolerance and chest pain are common symptoms in patients with pectus excavatum (pectus). In a prospective observational study of 327 pectus patients nearly two-thirds reported limited endurance and shortness of breath with exercise and more than half had chest pain1. The frequency of symptoms is also common; an online international survey of 331 pectus patients found 46% reported daily dyspnea and chest pain and another 19% reported weekly symptoms2.
The mechanisms leading to the symptom burden in pectus patients are currently unclear. Many investigators propose the exercise intolerance in pectus is directly related to compromise in the cardiovascular response from the anatomic distortion of the chest wall3-5. In more extensive cases of pectus, the internally displaced chest wall may compress the lungs and may reduce resting lung volumes. In a study of over 1,500 Pectus patients collected over 20 years, Kelly et al reported the distributive curve for forced vital capacity (FVC) and forced expiratory volume at one second (FEV1) are significantly shifted to lower values compared with normative standards6. Two smaller studies also demonstrated small but significant decreases in the FVC and FEV1 when comparing pectus with age-matched controls5,7.
There remains controversy regarding whether pulmonary defects in pectus physiologically impact exercise capacity. There is no evidence that individuals with pectus have intrinsic defects in the lung parenchyma based on autopsy studies of 62 patients who died of causes unrelated to pectus excavatum8. Further, there were no differences in measurements of gas exchange by diffusion of carbon monoxide between pectus and controls5. Therefore, if pectus defects directly contribute to exercise intolerance, the most likely mechanism would be secondary to a restrictive or obstructive impairment impeding increased tidal volume demand during exercise. Some investigators report regional chest wall motion defects to the lower ribs and sternum limiting ventilatory capacity with forced exhalation9,10. Whether these defects physiologically impact exercise capacity is unclear with some authors asserting that tidal volumes are not impacted during exercise to the extent that exercise capacity would be limited11-13.
The goal of this study was to evaluate the relationship between pectus severity and pulmonary outcomes in pectus patients referred to The Chest Wall Center at Cincinnati Children’s Hospital Medical Center (CCHMC). We describe the results of these physiologic studies which included patients with varying degrees of pectus severity to test the hypothesis that significant pectus deformities are associated with a pulmonary impairment during exercise. We also sought to identify if resting pulmonary function measurements are associated with subjective or objective measures of exercise intolerance.