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.