Aim of the Study: Until traction techniques emerged, delayed primary repair had been the method of choice to preserve the oesophagus in oesophageal atresia, but the timing of the anastomosis varied. Some advocated that the size of the baby, and thus its weight, must be taken into account. We therefore hypothesized that body weight predicts oesophageal length in rodents.
Methods: We explanted the oesophagi of 18 Sprague-Dawley rats, aged 15 to 444 days (n=2/timepoint), and measured body weight, oesophageal length, and weight. We conducted an exploratory analysis (n=5) to achieve a statistical power of 95% and conducted uni- and multivariate analyses. The experiments complied with the directive 2010/63/EU.
Main Results: Body weight correlated (R=0.96) almost perfectly with oesophageal length, whereas the correlation to age was less (R=0.819). Both factors were significant predictors of oesophageal length in univariate analyses (P<0.001). An almost perfect correlation (R=0.976) also occurred between oesophageal weight and length, in which the latter was a univariate significant predictor of the former (P<0.001). Moreover, age and body weight correlated (R=0.911) and age was a predictor of body weight (P<0.001). We built a multinomial model to predict oesophageal length based on body weight, age, and an interaction term of them to account for a possible interaction between body weight and age. The multivariate model was statistically significant (P<0.001) and had an excellent goodness-of-fit (adjusted R²=0.933). The equation reads oesophageal length=3.366cm+0.011*body weight[grams]-0.005*age[days]. Only body weight was a statistically significant predictor of oesophageal length (P<0.001), whereas age (P=0.05) and the interaction term (P=0.420) were not.
Conclusions: Oesophageal length in rats can be predicted by the body weight. Probably, a child’s weight may be a more important predictor for oesophageal length than age, too.