The volume changes seen in surgical practice often affect the extracellular fluid. Hartmann’s solution ( Ringer’s lactate) (Contains lactate and calcium)Ĭhanges in the volume or composition of the body fluids (which may occur before, during, or after surgery) can cause a severe physiological disturbance and should therefore be corrected promptly. Insensible loss: 1000 ml (up to 1700 in hot climate)Ī minimum urinary output of approximately 400 ml in 24 hours is required to excrete the end products of metabolismĮndogenous: 200 ml (from oxidation of ingested food.)
Body fluid compartments vascular endothelium skin#
To a lesser degree the skin and lungs affect water losses, but do not regulate them. The kidney regulates, to a large degree, the volume and composition of body fluid. In the normal individual, the amount of water and electrolytes excreted each day balances what is taken in in foods and fluids. Daily average water and electrolyte exchanges Never give pure water intravenously, as it causes dangerous haemolysis. The main cations are potassium and magnesium, with phosphates and proteins as the major anions.Īfter intravenous infusion, the water contained in physiological saline tends to remain in the extracellular compartment, but the water contained in glucose solutions is distributed throughout all body fluid compartments, the glucose being metabolized. Intracellular fluid has a different ionic composition to extracellular fluid. Blood, plasma, and colloids used as plasma substitutes, for example dextran, hydroxyethyl starch, and gelatin solutions (which are known as “plasma expanders”), remain in the intravascular compartment longer and are therefore more effective in maintaining the circulation. For this reason, they are effective in raising the intravascular circulating volume for only a short time if there is a deficit of fluid throughout the extracellular compartment. Electrolyte solutions, such as physiological (normal) saline and Ringer’s lactate solution (Hartmann’s solution), can pass into the interstitial space when they are administered intravenously. If there is a water deficit in the intra vascular compartment, water and electrolytes pass from the interstitial compartment to restore the circulating blood volume. Interstitial fluid has an ionic composition similar to that of plasma. Only a small proportion of the body’s potassium is present in plasma, but the concentration of potassium ions is crucial to cardiac and neuromuscular function. The protein in plasma is responsible for the intra vascular colloid osmotic pressure, a major determinant of the movement of fluid across the capillary endothelium.
Water and electrolytes move freely between plasma (intravascular compartment) and the interstitial fluid, but plasma proteins enter the interstitial fluid only when the capillary endothelium is damaged, for example as a result of septic shock or burns. Plasma contains proteins (chiefly albumin) and ions (mainly sodium, chloride, and bicarbonate). Physiologically, these three compartments of body water are interdependent. The extra cellular fluid is sub divided into Intravascular (plasma) comprising 2/3 of extra cellular fluid and Interstitial which comprises 1/3 of extra cellular fluid.
Females have lower body water (45 –60%) because of the high fat content of their body. In regard to this, 55% – 60% of body weight for a 70 Kg young man is water. The total body water constitutes 50 – 85% of total body weight depending on age and lean body mass (muscle mass). Daily average water and electrolyte exchanges.
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