E. Port1, F. Hebal1, C. Hunter1,2, F. Abdullah1,2, B. Malas1, M. Reynolds1,2 1Ann and Robert H Lurie Children’s Hospital of Chicago,Pediatric Surgery,Chicago, IL, USA 2Feinberg School Of Medicine – Northwestern University,Surgery,Chicago, IL, USA
Introduction: Assessment of Pectus Excavatum (PE) deformity in patients undergoing surgery is limited to Haller Index (HI), a preoperative measurement of severity, requiring use of computed tomography (CT). This measure has been used for over 20 years though there is little data validating its accuracy in PE versus non-PE patients. In our clinical experience, patients with normal chest appearance have registered HI beyond 3.25, a threshold frequently used to qualify patients for surgery and insurance reimbursement. A Correction Index (CI) measuring the ratio of the PE defect to a “healthy” chest diameter has been previously proposed as an alternative to HI with promising results. Our prior study demonstrated the accuracy of extrapolating post-operative HI and CI without CT radiation using White Light Scanning (WLS), a novel 3D imaging modality to measure PE deformity parameters. The purpose of this study was to demonstrate that a significant proportion of postoperative PE patients register severe HI despite a normal appearing chest and normal measurements by another validated metric of severity.
Methods: We conducted a prospective study of pre and postoperative WLS scans in PE patients from 2015-2018. HI and CI were measured in these scans and descriptive analysis assessed the postoperative change in severity indices. Patients with postoperative HI beyond 3.25 despite normal chest appearance and normal CI measurements were identified. Postoperative CI <5% was considered normal, and logistic regression was used to determine if other parameters are associated with a severe HI measurement in an otherwise normal chest. Metrics of chest dimensions assessed include mediolateral (ML) diameter, midclavicular anteroposterior (AP) diameter, and circumference at the level of defect.
Results: A total of 41 patients who underwent repair for PE had complete scan data available for analysis. Nine(22%) patients had estimated HI ?3.25 despite normal CI and chest wall appearance on post-operative scans. Greater chest circumference (OR: 1.04; CI: 1.01-1.07; p<0.02) and shorter midclavicular AP diameter (OR: 0.91; CI: 0.82-0.98; p<0.03) were significant factors associated with a HI >3.25 despite an otherwise normal chestwall. Figure 1 shows pre and postoperative measurements with common thresholds.
Conclusion: This study demonstrates that HI can register a severity warranting surgical intervention in patients with a corrected PE defect and flat appearing chest. In a preoperative cohort these findings represent a potential for mischaracterization of severity in PE patients that could warrant unnecessary intervention. Future studies will examine modifications to HI and alternatives to improve assessment of severity of PE.
