Haller Index Does Not Predict Physiologic Impairment In Children And Adolescents With Pectus Excavatum.

Abstract

Background: Pectus excavatum (PE) is a chest wall defect that may be associated with lung disease and exercise impairment. The Haller index (HI) is a marker of chest wall compression measured by chest CT and has been used as a marker of PE severity. Discordance between extent of cosmetic abnormality and clinical symptoms has been observed. PURPOSE: The study was designed to examine the relationship of HI and markers of pulmonary function and exercise performance. METHODS: Forty-one subjects with PE, 11F:30M, mean age 14.1 ± 3.9 years (5.4 - 22.8 yrs) underwent an evaluation including assessment of lung volume, spirometry, respiratory muscle strength, and exercise tolerance. Chest CTs were obtained with a HI measured per published standards. Values are expressed as mean ± standard deviation. Pulmonary function and exercise parameters are expressed as percent of predicted. Spearman correlation coefficients were measured. Significance was set as p<0.05. RESULTS: The total lung capacity (TLC) was 97.4 ± 16.9 % and forced vital capacity (FVC) was 97.2 ± 14.7%. Peak inspiratory and expiratory muscle strengths were reduced (PImax 78.5 ± 22.5; PEmax 64.2 ± 17.4%). Exercise tolerance was normal whether expressed as VO2 (88.2 ± 17.4%) or peak work capacity (PWC) (100.4 ± 18.1%). An impaired breathing reserve (VE/MVV: 85.2 ± 18.4), an elevated peak respiratory rate (58.1 ± 12.9), and elevated ventilatory equivalents at ventilatory threshold (VE/VO2: 34.2 ± 5.9; VE/VCO2: 33.2 ± 7.9) were observed. HI (4.2 ± 1.2) was weakly correlated to TLC (r=−0.36) and FVC (r=−0.51). No correlation was seen between HI and PImax, PEmax, PWC, VO2, RR, or VE/MVV. Discussion: While the classic description of PE includes lung restriction, our study did not demonstrate consistent restriction despite abnormal HI. There was a correlation between HI and lung volume. Total exercise performance appeared normal but was associated with impaired ventilatory reserves, impaired respiratory muscle strength, and breathing limitations. The HI did not appear to be associated with these abnormal findings. CONCLUSION: The HI appears to be associated with lung volume compromise. However, HI appears to be a poor predictor of associated physiologic impairment and does not replace the need for physiologic testing to determine the extent of compromise caused by the defect.