Over the past decade there has been considerable interest in lung water
and solute exchange, stimulated by the clinical importance of pulmonary
oedema. Thus, there is more information available on pulmonary oedema
and its physiological consequences than on the control of lung water under
normal conditions. It is known that foetal and neonatal lungs are fluid￾filled; the way in which the lung is transformed into an air-filled gas-ex￾changing organ at and shortly after birth has been studied by physiologists
and paediatricians for many years. The subject is not included in this re￾view, but a recent Ciba Foundation symposium (1976) covers this topic.
There is little, if any, information on variations in lung water with age,
exercise, pregnancy or the menstrual cycle. This is primarily because accu- Lung Water Balance 7
rate measurements of lung water in vivo have been, and still are, difficult
to achieve (Sect. 7). Much has been written about pulmonary oedema;
particular note should be taken of Staub's classic review (1974) and a re￾cent book edited by Fishman and Renkin (1979).