The Journal of Thoracic and Cardiovascular Surgery, Vol 77, 252-258, Copyright © 1979 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Lung transvascular fluid dynamics with extracorporeal membrane oxygenation in unanesthetized lambs
AG Delaney, WM Zapol and AJ Erdmann 3d
Extracorporeal membrane oxygenation (ECMO) is used for long-term support of
patients with acute respiratory failure. We investigated the effect of
partial venoarterial (VA) and venovenous (VV) bypass with filler-free
silicone spiral-coil membrane lungs on steady-state lung transcapillary
fluid filtration in six unanesthetized lambs for periods of 11 to 32 hours.
Using three thoracotomies we prepared animals to collect lung lymph; lymph
obtained in this way is representative of lung interstitial fluid. By
studying lymph flow and composition we demonstrated that the permeability
of the pulmonary capillaries does not change during prolonged partial VV or
VA bypass with a membrane lung. There was no accumulation of lung water
during bypass, and lung protein and fluid leak neither increased not
decreased with bypass flows equivalent to those used clinically. Thus
prolonged use of ECMO in unanesthetized lambs appears to be neither harmful
nor beneficial to the steady-state dynamics of fluid exchange in the lung.
Furthermore, total pulmonary blood flow is not a determinant of net fluid
filtration across the lung microcirculation.