A single, lightweight, valveless, non-absorber breathing system, which
functions with near maximal efficiency (hence the name Maxima) in spo
ntaneous and controlled ventilation is described. It may be classified
as an enclosed efferent afferent reservoir (FEAR) breathing system an
d is characterised by the selective elimination of alveolar gas in all
modes of ventilation. A functional description explains how this is a
chieved in the system in spontaneous and controlled ventilation. The p
otential for error which arises in combination systems for different s
witch positions with different modes of ventilation is avoided, as it
is a single universal system. With no moving parts, mechanical reliabi
lity is guaranteed. The apparatus deadspace is negligible making the s
ystem usable even in neonates. Finally, the characteristics of the the
oretical ideal non-absorber circuit are discussed as this illustrates
the objective of the circuit design and important physical principles
surrounding its function.