Abstract
This paper deals with the variations in perspiratio insensibilis during normal nasal respiration and breathing through a tracheostoma. Widely used methods for moistening the inspired air of tracheotomized patients are listed and discussed. An aluminium foil heat-and-moisture exchanger (HME) for direct application to the tracheal cannula is described and tested experimentally in order to determine its air flow resistance as well as its heat and moisture recovery efficiency.