Ovine model of congenital chest wall and spine deformity: From birth to 3 months follow-up

Background

The evolution and treatment of lung alterations related to congenital spine and chest wall deformities (CWD) are poorly understood. Most animal models of CWD created postnatally were not evaluated for respiratory function. The goal of our study was to evaluate the effects of a CWD induced in utero on lung growth and function in an ovine model.

Methods

A CWD was induced in utero at 70–75 days of gestation in 14 ovine fetuses by resection of the 7th and 8th left ribs. Each non-operated twin fetus was taken as control. Respiratory mechanics was studied postnatally in the first week and at 1, 2, and 3 months. Post-mortem respiratory mechanics and lung histomorphometry were also assessed at 3 months.

Results

Eight out of 14 CWD lambs (57%) and 14 control lambs survived the postnatal period. One severe and five mild deformities were induced. At birth, inspiratory capacity (25 vs. 32 mL/kg in controls), and dynamic (1.4 vs. 1.8 mL/cmH₂O/kg), and static (2.0 vs. 2.5 mL/cmH₂O/kg) respiratory system compliances were decreased in CWD lambs. Apart from a slight decrease in inspiratory capacity at 1 month of life, no other differences were observed in respiratory mechanics measured in vivo thereafter. Postmortem measurements found a significant decrease in lung compliance—for each lung and for both lungs taken together—in CWD lambs. No differences in lung histology were detected at 3 months in CWD animals compared to controls.

Conclusions

Our study is the first to assess the effects of a prenatally induced CWD on lung development and function from birth to 3 months in an ovine model. Our results show no significant differences in lung histomorphometry at 3 months in CWD lambs compared to controls. Resolution at 1 month of the alterations in respiratory mechanics present at birth may be related to the challenge in inducing severe deformities.