ABSTRACT
The adult body contains approximately 40-45 litres of water, equivalent to 60-65 per cent of body weight. This substantial volume provides more than a body ‘filler’: it supports tissues, enables the circulation of nutrients, and is the medium in which most if not all biochemical reactions take place. Fluid distribution and composition is therefore important and body fluid homeostasis must ensure that this volume and composition is conducive to optimal cell and tissue functions. Surgery has potentially major implications for the maintenance of body fluid homeostasis because of the practice of fasting patients preoperatively, of the surgical procedure itself, the responses to trauma, or the incidence of post-operative complications.
