FEASIBILITY OF A PHOTOSYNTHETIC ARTIFICIAL LUNG

The success of extracorporeal membrane oxygenation (ECMO) for the trea tment of acute respiratory failure has led to consideration of the dev elopment of a more portable, and perhaps even implantable, artificial lung. The authors suggest a bioregenerative life support system that i ncludes a photosynthetic organism that can remove CO2 and produce O-2 in the presence of an energy source. To build a model of such a photos ynthetic artificial lung, the photosynthetic capability of a high temp erature strain of the algae Chlorella pyrenoidosa was maximized at a c ell density of 25 million cells/ml to serve as the O-2 producer and CO 2 remover. The ''patient'' in this model was comprised of 1 L of mediu m or 350 ml of blood, interfaced with the photosynthetic system across a gas transfer membrane. The experiments demonstrated the ability of the plant cells to supply O-2 and remove CO2 from the ''patient'' with a maximum rate of 0.55 mmoles/L/hr under the most favorable measured operating conditions. The projected rate of 1.0 mmoles/L/hr required f or physiologic applications is not totally an absurd idea, with a slig htly modified set-up. Modifications may be in the form of regulating t he photosynthetic pathway or genetically engineering a hybrid strain w ith enhanced O-2 producing and suppressed photoinhibition capacity.