Anisotropic Hydrostatic Intraluminal Esophageal Stretch: Prototype Fabrication and Initial Safety T
Christopher D Graham, MD1, Hester F Shieh, MD1, Mustafa Karabas, MS2, David Zurakowski, PhD1,Anne Hansen, MD1, MPH; Dario O Fauza, MD, PhD1
1Departments of Surgery and Neonatology, Boston Children's Hospital and Harvard Medical School; 2Wyss Institute for Biologically Inspired Engineering at Harvard University
Background: We sought to fabricate and perform initial safety testing of a hydrostatic device for intraluminal axial distension of the esophagus, as a minimally invasive means of inducing esophageal stretch/lengthening.
Methods: The device consists of a modified infant endotracheal tube fitted with a unique anisotropically expandable balloon at its distal end. Structural integrity and functional parameters of the prototypes were measured in an expansion test rig. Subsequently, the impact of balloon inflation pressures on esophageal perfusion was examined in lambs (n=6) with surgically created esophageal atresia. The device was placed in the proximal esophageal pouch and its intraluminal pressures were correlated with esophageal perfusion as assessed with a microvascular oximeter based on resonance Raman spectroscopy of hemoglobin. Statistical analyses included repeated measures with generalized estimating equations and inverse regression.
Results: The helicoidal architecture of the balloon led to consistent anisotropic expansion, with a stable relationship between balloon length, body width, and tip radius during liquid-based expansion within the test rig. There was a significant decrease in oxygen saturation in the esophageal wall at intraluminal pressures ≥ 30mmHg (Pearson r=-0.58, Wald test=17.5, P=0.027). Regression analysis identified that an intraluminal pressure of 32mmHg correlated with oxygen saturations below 60% (P<0.001).
Conclusion: Controlled axial distension of an esophageal pouch can be achieved via an intraluminal anisotropically expandable hydrostatic device under a predictable, safe relationship between device pressure and esophageal perfusion. Intraluminal esophageal stretch may become a practical option for esophageal lengthening in the management of long gap esophageal atresia.
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