DISORDERS OF FLUID ELECTROLYTE BALANCE液体和电解质平衡失调.ppt

Disorders of Fluid Electrolyte Balance University of San Francisco Dr. M. Maag ?2003 Margaret Maag Class 6 Objectives Upon completion of this lesson, the student will be able to describe the outcomes associated with hypo and hypervolemia. distinguish between the different etiologies of major electrolyte imbalances. list the manifestations of electrolyte imbalances. identify normal distribution of ICF and ECF. state the normal serum values for Na, K, Cl, Mg, PO4 ,Ca. Starling’s Law of the Capillary Fluids leave (filtration) or enter (re-absorption) the capillaries depending on how the pressure in the capillary and interstitial spaces relate to one another Volume re-absorbed is similar to volume filtered: “A net equilibrium” Regulates relative volumes of blood interstitial fluid Capillary Exchange The 5% of blood in the systemic capillaries = the bulk of blood that exchanges materials with systemic tissue cells Substances that pass through thin capillary walls into interstitial fluid and then into cells are: nutrients oxygen Substances that are secreted by tissue cells and removed from them are: wastes CO2 Fluids  Distribution of total body water (TBW) 60% of adult body weight is fluid Gender, body mass age considerations Intracellular (ICF, within cells = 40% of body weight) Extracellular (ECF, plasma, interstitial lymph =20% of body weight) 1 Litre water = 2.2lb or 1 kg Developmental Differences Infants young children Four areas of immature functioning Increased fluid intake and output relative to size Total body fluid is 20% more than adults Greater surface area relative to size: water loss through skin Increased metabolic rate up to 2 years Immature kidney function requires more fluid to excrete wastes Fluid Shifts“Third Spacing” Excess fluid in interstitial spaces and connective tissues between cells [edema] OR Excess fluid in potential spaces [effusion] peritoneal cavity pericardial sac synovial cavities of joints alveoli or intra-pleural spa