Demand controlled liquid ventilation of the lungs

Liquid breathing has been previously investigated in terms of unassisted breathing during total body immersion or forced liquid ventilation. The objective of this study was to investigate the feasibility of demand controlled assistance for liquid ventilation of the lungs. The basis for demand controlled assistance is to employ the animal's internal respiratory controller and sensory mechanisms to determine his own physiological needs such as tidal volume and breathing rate. Assistance is implemented by a liquid breathing system (LBS) which senses incipient respiratory excursions and provides optimum mechanical assistance by following and aiding spontaneous breathing. Results of animal studies with a demand controlled liquid breathing system are presented. Animal preparation, system components, and operation methods are described. Pulmonary mechanics recovery histories following liquid breathing are also presented. Animal experiments demonstrate that a demand controlled LBS provides adequate stability in the control of physiological parameters such as pO₂ and pCO₂.