title: Homeostasis--the key concept to physiological control.
abstract: The maintenance of body water content is a classic example of homeostasis at work. Water is continuously lost and added to the systems. The regulation of a balance between the factors involved demonstrates the dynamic nature of homeostatic processes. Surgery places additional demands on such processes, partly because there are additional factors in the balance equation and partly because of the hormonal responses to trauma which also affect water balance. Promoting the return to a balance state and maintaining it, during and after surgery, is important to patient well-being and may even facilitate recovery. The risks associated with a disturbance in water balance are of potentially greater consequence if there is water overload, particularly if the patient has underlying cardiovascular or respiratory problems. Slight dehydration is probably a better target to aim for in order to reduce such risk but there are no easy ways to achieve this state as individuals will vary in their responses to surgery. The hydration, and electrolyte, needs, will vary between patients so fluid therapies should be individualised. Whilst a patient's fluid balance chart provides a means of assessing water balance, the interpretation is complicated after surgery. An awareness of other signs is therefore essential.
authors.forename: J
authors.initials: J
authors.lastname: Clancy
authors.forename: A
authors.initials: A
authors.lastname: McVicar
mesh_terms: D004509:Education, Nursing, Continuing; D006801:Humans; D009871:Operating Room Nursing / Q000379:methods; D019990:Perioperative Care; D014882:Water-Electrolyte Balance / Q000502:physiology*