N. L. Werner1, M. Coughlin1, C. J. Perez-Torres4, H. Parmar5, R. Shellhaas2, J. Barks6, J. R. Garbow3, G. B. Mychaliska1 1University Of Michigan,Pediatric Surgery,Ann Arbor, MI, USA 2University Of Michigan,Pediatric Neurology,Ann Arbor, MI, USA 3Washington University,Radiology,St. Louis, MO, USA 4Purdue University,Radiological Health Sciences,West Lafayette, IN, USA 5University Of Michigan,Radiology, Division Of Neuroradiology,Ann Arbor, MI, USA 6University Of Michigan,Pediatric Neonatolgy,Ann Arbor, MI, USA
Introduction: The effect of an extracorporeal artificial placenta (AP) on the developing brain is unknown. The aim of this study was to evaluate brain structure after AP support using magnetic resonance imaging (MRI).
Methods: Institutional guidelines for animal research were followed. AP lambs (n=5), with estimated gestational age (EGA) of 120±2 days (term=145 days), were cannulated for veno-venous ECMO on placental support and delivered. AP support with heparin was maintained for 7±0.5 days before euthanasia at EGA~127 days. Control(C) lambs, with an EGA of 120±2 days (n=3) or 127±2 days (n=2), were euthanized immediately after delivery. All brains were flushed with formalin for fixation and then characterized by MRI. A 25-direction diffusion sequence with an additional b=0 image (no diffusion weighting) was used to calculate fractional anisotropy (FA) and apparent diffusion coefficient (ADC) to qualitatively evaluate white-matter integrity. The b=0 image, plus a T1 sequence, were used to measure brain volume and hull, and to evaluate for hemorrhage.
Results: The AP brains had no evidence of hemorrhage or white-matter injury (Figure A, B). Brain volume appeared to increase with gestational age (C-120 day 1.77E4 mm3 v. C-127 day 1.79E4 mm3). AP brains were on average smaller than either control (1.55E4 mm3). The hull increased with gestational age (C-120 day 1.92E4 mm3 v. C-127 day 2.08E4 mm3). The volume/hull ratio, which is surrogate marker of cerebral folding, showed AP brains with a ratio between the 120 and 127 day controls (C-120 days 86% v. AP 89% v. C-127 days 92%). The ventricles of AP brains were mildly enlarged compared to controls (Figure C, D).
Conclusion: The artificial placenta provided long-term extracorporeal support with no evidence of brain hemorrhage or white-matter injury. The data suggest some ongoing brain development during AP support. Compared to controls, the AP brains were smaller and had larger ventricles; the clinical significance of these findings is unknown.
