Defect-diaphragmatic ratio: a new parameter for assessment of defect size in neonates with congenital diaphragmatic hernia

The aim of our study is to introduce a new objective method of perioperative evaluation of the size of diaphragmatic defect to enable comparison of results among various centres and methods used for diaphragmatic reconstruction. Prospective observational study of neonates with congenital diaphragmatic hernia (CDH) and respiratory distress within 24 h of birth operated on from January 2009 to December 2011. Weight, length, thoracic shape and the diameters of diaphragmatic defect were measured. To determine the relative size of the defect, a defect-diaphragmatic ratio (DDR = defect area:diaphragm area x 100) was calculated. The measured and calculated data were subsequently compared between Gore-Tex patch group (GT) and primary repair group (PR). Mann-Whitney U test was used for statistical analysis. Forty-seven patients with CDH were admitted during study period. The overall survival rate was 79 % (37/47). Preoperative stabilization was achieved in 85 % (40/47). Survival of operated neonates was 93 % (37/40). Diaphragmatic reconstruction with Gore-Tex patch was used in 7 neonates (17 %), and primary repair in 33 (83 %). Mortality in Gore-Tex group was 29 %; mortality in primary repair group was 3 %. Data of anthropometric measurement were complete in 34 children (5 GT and 29 PR). Significant differences were found between GT group and PR group in the size of diaphragmatic defect with the transverse and sagittal diameters of defect (48.0 +/- A 5.7 vs. 30.1 +/- A 5.9, P < 0.00061; 34.0 +/- A 12.5 vs. 16.0 +/- A 7.3, P < 0.0022) and DDR (18.29 +/- A 4.60 vs. 5.77 +/- A 3.28, P < 0.0005), respectively. The value of DDR as an objective criterion of the extent of diaphragmatic defect was confirmed by the close correlation between DDR and feasibility of primary repair in the study group. This objective assessment of defect size may improve comparing various surgical techniques and results of different centres, and thus facilitates sharing experience with management of neonates with CDH.