A brief review: liquid ventilation.

The liquid-filled lung preparation has provided physiologists with a unique technique for varying the physical properties of respiratory media and studying their effect on basic pulmonary processes. More recently, liquid breathing, ventilation of the lungs with an oxygenated fluid, has extended the applicability of the liquid-filled lung to include a wide variety of environmental and clinical research areas. This article is an account of the history of liquid breathing based on a review of 60 publications dating back to 1920. The physiologic status of this experimental preparation has continuously advanced due to technical changes in experimental approach and improved understanding of the implications of fluid breathing on overall systemic physiology. In this regard, the evolution of the liquid breathing concept from the saline-filled lung to ventilation with inert liquids is presented. Emphasis is placed on how liquid breathing can be used as an effective research tool for expanding our understanding of normal respiratory physiology and how this technique may be of benefit to other areas of science. Finally, like most techniques in biological investigations, liquid ventilation has certain limitations. Therefore, this review summarizes the rationale behind various experimental approaches, the nature and tractability of limitations, and the results which can be safely drawn from experimental studies to date.