水电解质平衡失调的处理ppt课件

Fluid & Electrolyte Management 水电解质平衡失调的处理 Department of Surgery 2002.9 lThe surgical patient is liable to develop numerous disorders of body fluid volume and composition, some of which may be iatrogenic. Understanding the physiological mechanisms that regulate the composition and volume of the body fluids and the principles of fluid and electrolyte therapy is therefore essential for patient management. Body water & its distribution 体液的分布 lTotal body water (45-60% body weight) l Intracellular (ICF) 2/3(40%bw) Extracellular (ECF)1/3 l Plasma 25%(5%bw) Interstitial fluid75%(15%bw) Body water & its distribution Composition ECF ICF l Electrolyte = l Proteins l (Albumin Colloid osmotic pressure) l Ions of body fluid l Cation sodium Na+ potassium K+ l magnesium Mg2+ l Anion chloride Cl- organic phosphate P3 l bicarbonate HCO3- proteins Regulation of body fluid balance 体液平衡的调节 l by kidneys: l (1) filtration and reabsorption of sodium, which adjusts urinary sodium excretion to match changes in dietary intake l (2) regulation of water excretion in response to changes in secretion of antidiuretic hormone. l to keep the volume and osmolality of body fluid constant within a few percentage points despite wide variations in intake of salt and water. A corollary is that analysis of the composition. Regulation of body fluid balance 体液平衡的调节 l (1) filtration and reabsorption of sodium, which adjusts urinary sodium excretion to match changes in dietary intake l (2) regulation of water excretion in response to changes in secretion of antidiuretic hormone. These two mechanisms allow the kidneys to keep the volume and osmolality of body fluid constant within a few percentage points despite wide variations in intake of salt and water. A corollary is that analysis of the composition. Regulation of body fluid balance 体液平衡的调节 lThe stability of fluid (hypothalmus- posterior pituitary-antidiuretic hormone system) and electrolytes (rennin- aldosterone) is regulated by neuroendocrine system. Maintenance Of Acid Bace Balance 酸碱平衡的维持 l In normal human body, when H+ concentration or pH7.35-7.45 is maintained, normal physiometabolic function can be carry out. l During body metabolism, producing acid and base , H+ concentration often changes. l Relative steady state is maintained by buffer system of body fluid, lung and kidney. Maintenance Of Acid Bace Balance lHCO3- and H2CO3 is the most important buffer system. When HCO3- / H2CO3 =20/1 palsma pH keeps normal. lLung excretes CO2 regulatesPCO2 and H2CO3 concentration. lLung functional disturbance causes acid- base imbalance and fail to regulate acid base balance. Maintenance Of Acid Bace Balance l Kidney can excrete fixed acid and excess alkaline material. Abnormality of renal function can not regulate acid base balance and cause acid base imbalance. l Kidney regulates acid-base imbalance by 1) H+ and Na+ exchange 2) HCO3- reabsorption 3) Excreting NH3+ H+ NH4 4) Excreting H+(acidification of urine) DISTURBANCE OF BODY FLUID 体液代谢失调 lVolume disturbance (isotonic dehydration) lConcentration (hypotonic or hypertonic dehydration) lComposition (hypokalemia or hyperkalemia, hypocalcemia or hypercalcemia etc) Disturbance of water- sodium metabolism 水和钠代谢紊乱 l Water and sodium have close interrelationship. Water deficit and sodium deficit are certainly concomitant in surgical practice. l But the deficit proportion may be different. According to different deficit proportion, water deficit may be divided into three types: Isotonic water deficit (dehydration) Hypotonic water deficit Hypertonic water deficit Isotonic dehydration 等渗性缺水 lAcute water deficit or mixed water deficit most often occur in surgical patients lProportion of water and sodium deficit is equal in plasma lNo change in ECF osmolality and ICF volume lStimulation of rennin- aldosterone and aldosterone increase Isotonic dehydration Common causes Acute gastrointestinal losses: vomiting, enteric fistulas, nasogastric suction, enterostomies Fluid into infected area or peritoneal cavity: peritoneal or retroperitoneal infection, intestinal obstruction, burns and so on. Isotonic dehydration Clinical manifestation l nausea, anorexia, weakness, Urine decrease, without severe thirst. l Dry tongue, sunken eye, dry skin, and decreased elasticity of skin. l fluid loss 5% of body weight or 20% extracellular fluid causes small and rapid pulse, moist cooling extremity, unstable or decreased blood pressure. l 6-7% of body weight (30-35% of extracellular fluid) causes severe shock often with acidosis. l If much gastric juice loss, with metabolic alkalosis. Isotonic dehydration Diagnosis lHistory: alimentary fluid or other fluid loss lClinical manifestation lLaboratory exam. Increase of RBC, HCT and Hb Sodium and chloride in plasma is normal. Increase of urine specific gravity. Artery blood gas analysis may show acidosis. Isotonic dehydration Treatment l Remove causes l Replenish blood volume by balanced salt fluid or isotonic saline. l If pulse increase, blood pressure decrease 5% of body weight fluid loss, give 3000ml solution. l If no manifestation of decreased blood volume, give 1/2-2/3 namely 1500-2000ml or of calculated volume. l Daily requirement should be given. Isotonic dehydration Two kinds of balanced salt fluids l 1.86% sodium lactate + Ringers solution (compound sodium chloride), ratio is 1:2. l (2)1.25% sodium bicarbonate + isotonic saline, ratio is 1:2. Isotonic dehydration Isotonic saline l Contains 154mmol/L Na+ and 154mml/L Cl-, but serum 142mmo1/L Na+ and 103mmo1/L C1-. l In isotonic saline, Cl- concentration is 50mmo1/L higher than that in serum. l If give much isotonic saline without normal renal function can cause hyperchloremic acidosis. l Giving balanced salt fluid is better for treating isotonic water deficit. Isotonic dehydration After correcting dehydration l Potassium excretion increases, fluid replenishment makes potassium concentration decrease, so we must pay attention to hypopotassemia. l If urine is more than 40m1/h, give potassium Hypotonic dehydration 低渗性缺水 lIt is also called chronic water deficit or secondary water deficit. lSodium deficit is more than water deficit. lExtracellular fluid is at lower osmotic pressure. lBlood volume severely decreases and causes shock called hyponatrimia shock. lantidiuretic hormone decrease and urine increase, ECF ostolality increase Hypotonic dehydration Causes lContinual loss of gastrointestinal juice: repeated vomiting, gastrointestinal suction long time lChronic exudation from major wound area lExcess excretion sodium from kidney, (some diuretics without sodium placement) lIsotonic dehydration with more water placement Hypotonic dehydration Clinical manifestation lWithout thirst. Nausea, vomiting, giddiness, visual disturbance, weakness, rapid small pulse, and orthostatic hypotension (giddiness, faint). l Blood volume falls obviously and renal filtration decreases. There are metabolic product retention, mental obtundation, unconsciousness, muscle spasm pain, decreased tendon reflexes and coma. Hypotonic dehydration Mild sodium deficit lThere are fatigue (lassitude), giddiness and numbness of the extremities, lSodium in urine falls. lSerum sodium is less than 135mmo1/L. Sodium loss is about 0.5g/kg. Hypotonic dehydration Moderate sodium deficit lAbove mentioned symptoms lNausea, vomiting, rapid small pulse, unstable blood pressure or decreased, lower pulse pressure, collapsed superficial vein, vague vision and orthostatic faint. lUrine volume falls. There are no sodium and chloride in urine. l Serum sodium is less than 130mmol/L. 0.5- 0.75g/kg sodium is lost Hypotonic dehydration Severe sodium deficit lThere are unconsciousness, muscle spasm pain, decreased tendon reflexes or negative lstupor, coma and shock. lSerum sodium is less than 120mmo1/L, about 0.75-1.25g/kg sodium is lost. Hypotonic dehydration Diagnosis l History l Clinical manifestation l Na+ and Cl- in urine fall, spgr40ml lComplete correction needs long time, oral intake Hyperkalemia 高钾血症 Serum K+ 5.5mmol/L Causes lOral intake, infusion, blood transfusion lPoor renal function e.g. acute renal failure, K+ retention diuretics (antisterone), poor adrenal cortical function lAbnormal K+ distribution (acidosis , crush injury, haemolysis) Hyperkalemia Clinical manifestation lNausea and vomiting, colicky abdominal pain and diarrhea lCirculatory disturbance, pale, cooling and bluish, hypotension, slower hea