05 体液平衡与酸碱平衡紊乱

nullFluid and Electrolyte BalanceFluid and Electrolyte BalanceWord and VocabularyWord and Vocabularyelectrolyte电解质 dehydration脱水 sodium钠 potassium钾 urea 尿素 creatinine肌酐 chloride氯 bicarbonate碳酸氢 over-hydration水肿 anion阴离子 hyponatraemia低钠血症 constituent成分，组份 aldosterone醛固酮 acidosis酸中毒 alkalosis碱中毒 hyperkalaemia高钾血症 lethargy无生气的 mucous粘液 intracellular细胞内的 Cumulative累积的 extracellular细胞外的 interstitial细胞间的 schematic示意的 inlet入口 outlet 出口 visualise可视的 hydration水合作用 accumulate累积 cation阳离子 predominate主要的 ion离子 consequence结果 glomerular filtration rate 肾小球滤过率 variable变量 solute 溶质 solvent溶剂 semipermeable半透膜的 osmotic渗透的 shrink收缩 expand扩张 isotonic等渗的 formula公式， 规则 编码规则下载淘宝规则下载天猫规则下载麻将竞赛规则pdf麻将竞赛规则pdf flux 流动，变化 homeostatic稳态 deprive丧失 collapse崩溃 oxygen氧 nutrient营养 imbibe喝 overriding首要的 fluctuation波动 vulnerable易受攻击的 AVP(antidiuretic hormone,ADH)抗利尿激素 Perspiration出汗 respiration呼吸 hypothalamus下丘脑 posterior后的 pituitary approximately大约地 infantile婴儿 diarrhoea腹泻The importance to exam the fluid and electrolyte balance The importance to exam the fluid and electrolyte balance nullFluid and electrolyte balance is central to the management of any patient who is seriously ill. The most commonly requested biochemistry profile is the measurement of fluid and electrolyte Body Fluid CompartmentBody Fluid CompartmentThe intracellular fluid compartment (ICF) : is the volume of fluid inside the cells. The extracellular fluid compartment (ECF) : is the volume which lies outside cells. plasma Interstitial fluid It is important to understand the difference between the ECF and the effective circulating volume (ECV). The ECV is the portion of the ECF that is actively perfusing tissues. In some pathologic states (such as patients with heart failure, ascites, or edema), the ECV may be decreased despite an increase in the total ECF. These patients behave as if they are volume depleted despite an increase in the ECV. Water tank model of body fluid compartmentsWater tank model of body fluid compartmentsFluids taken orally or by intravenous infusion Urinary tract and insensible loss as surface evaporation nullDehydration and Over-hydration Dehydration simply means that fluid loss has occurred from body fluid compartments. Over-hydration occurs when fluid accumulates in body compartment The effect of volume depletion and volume expansion on the water tank model of body compartmentThe effect of volume depletion and volume expansion on the water tank model of body compartmentDehydration: loss of fluid in ICF and ECF due to increased urinary losses Over-hydration: increased fluid in ICF and ECF due to increased intakenullELECTROLYTES Sodium(Na+) is the principal extracellular cation Chloride(Cl-) and bicarbonate(HCO3-) are predominate anion in ECF Potassium(K+) is the principal intracellular cation Inside cells the main anions are the protein and phosphate OSMOLALITYOSMOLALITYOsmolality of a solution is decided by the overall number of solute particles in a specific compartment. Although body fluids vary greatly in their composition, and the concentration of substances differs in the different body fluids, the osmolality is identical.nullSodium ion is present at the highest concentration and hence make the largest contribution to the total plasma osmolality. And potassium ion’s concentration in ECF is less comparing with that in ICF, but the changes in the concentration in ECF are very important and may have life threatening consequences. Osmolality changes and water movement in body fluid compartmentOsmolality changes and water movement in body fluid compartmentThe osmolality in different body compartments must be equal. This is achieved by the movement of water across semipermeable membranes in response to concentration changes. Plasma osmolalityPlasma osmolality Plasma osmolality (Posm) is defined as the total amount of solute particles, including anions, cations and other solute, in 1 L water. Posm can be measured directly by osmometry or estimated by the following formula: plasma osmolality(mmol/kg) =1.86 plasma[sodium＋glucose＋urea](mmol/l)+9 The unit of all [Na+], [glucose] and [urea] is mmol/L. Because Na+ is the major cation and plasma is approximately 93% (0.93) water, the sum of the anions and cations can be approximated by multiplying the Na+ concentration by 1.86. The 9 mOsm/kg added represents the contribution of other osmotically active substance in plasma such as K+, Ca2+ and proteins. Thus, only Na+, urea, and glucose need to be measured. Posm normally is 275~300 mOsm/kg. Fluid and electrolyte balance: concepts and vocabularyFluid and electrolyte balance: concepts and vocabularyThe body has two main fluid compartments, the intracellular fluid and extracellular fluid. The ICF is twice as large as the ECF. Water retention (over-hydration)will cause an increase in the volume of both ECF and ICF. Water loss(dehydration) will result in a decreased volume of both ECF and ICF. Sodium ions are the main ECF cations. Potassium ions are the main ICF cations. The volumes of the ECF and ICF are estimated from knowledge of the patient’s history and by clinical examination. Serum osmolality can be measured directly or calculated from the serum sodium, urea and glucose concentration. WATER AND SODIUM BALANCEWATER AND SODIUM BALANCEBody water and the electrolytes it contains are in a state of the constant flux. It is important to maintain a steady state. Failure to maintain ECF volume, with the consequence of impaired blood circulation, rapidly leads to tissue death due to lack of oxygen and nutrients, and failure to remove waste product nullNormal water balanceFaeces(粪便) The regulation of water balance by AVP and osmolality The regulation of water balance by AVP and osmolality+_Normal sodium balanceNormal sodium balance The regulation of sodium balance by aldosterone The regulation of sodium balance by aldosteroneArterial natriuretic peptide 心钠素Regulation of volumeRegulation of volumeThe amount of sodium in the ECF determines what the volume of the compartment will be. Aldosterone and AVP interact to maintain normal volume and concentration of the ECF. When the ECF volume is low, aldosterone secretion is high. Thus as the patient begins to take fluids orally, any salt ingested is maximally retained. As this raised the ECF osmolality, AVP action then ensures that water is retained too.Water and sodium balanceWater and sodium balanceWater is lost from the body as urine and as obligatory “insensible” losses from the skin and lungs. Sodium may be lost from the body in prolonged vomiting, diarrhoea and intestinal fistulae. Arginine vasopressin(AVP) regulates renal water loss and thus causes changes in the osmolality of body fluid compartments. Aldosterone regulates renal sodium loss and controls the sodium content of the ECF. Changes in sodium content of the ECF cause changes in volume of this compartment because of the combined actions of AVP and aldosterone.Case history 4Case history 4A man is trapped in a collapsed building after an earthquake. He has sustained no serious injuries or food or water until he is rescued after 72 hrs. What will have happened to his body fluid compartments? Word and Vocabulary(1)Word and Vocabulary(1) Hypernatraemia diuresis 多尿 tubular 管状的 compulsive Nephrogenic 肾源的 deficit 不足，短缺 vomit fistula Hyperaldosteronism cortisol 皮质醇 mineralocorticoid 矿物（盐）皮质激素 pulmonary 肺的 oedema 水肿 ketoacidosis 酮症酸中毒 permeate 弥漫，渗透 synonymous 同义的 carcinoma 癌肿 shrivel v.皱缩 incapacitate v.使不能 comatose 昏睡的 extremity （肢体） 末端，极点，困境 ambulant 可走动的，可起床的 Sacral 神圣的 ,骶骨的 recumbent 横躺着的 ，休息的 saline 盐的，盐井 Normotensive 血压正常的（人） pneumonia 肺炎 convulsion 震动，痉挛 Word and vocabulary(2)Word and vocabulary(2)abscess 脓肿 malignancy 恶毒，恶性肿瘤 nausea 恶心，极度厌恶 mineralocorticoid 矿物（盐）皮质激素 protract 延长，拖延 tachycardia 心动过速 Hypoglycaemia 高血糖 arginine 精氨酸 vasopressin 血管加压素 postural 体位的，姿势的 Anorexia 厌食 anaemia 贫血 venous stimuli 刺激物，激励 disturbance 扰乱，失调 hypoalbuminaemia 低蛋白血症 sunken 凹陷的 pleural 胸膜的 Pseudohyponatraemia 假性低钠血症 sachet 香袋，袋子 gastrointestinal 胃肠道的 peritoneal 腹膜的 Detention 延迟，阻止 artefact 人工制品 1.Hypernatraemia is an increase in serum sodium concentration above the reference range of 150mmol/L. 2.The causes of the hypernatraemia may be: 1)water depletion (decreased intake, excessive loss) 2)water and sodium depletion 3)excessive sodium intake or retention in the ECF 4)very rarely renal failure with inability to excrete sodium1.Hypernatraemia is an increase in serum sodium concentration above the reference range of 150mmol/L. 2.The causes of the hypernatraemia may be: 1)water depletion (decreased intake, excessive loss) 2)water and sodium depletion 3)excessive sodium intake or retention in the ECF 4)very rarely renal failure with inability to excrete sodiumHypernatraemia is commonly associated with a contracted ECF volume, and less commonly with an expanded compartmentHypernatraemia is commonly associated with a contracted ECF volume, and less commonly with an expanded compartmentVolumes of ECF and ICF are reduced. ECF volumes is shown here to be slightly expanded; ICF volume is normalnullWater depletionWater depletionFrom a decreased intake From an excessive loss The most common reason is: the water intake fails to match the insensible water loss Water and sodium depletionWater and sodium depletionHypernatraemia occurs only if more water than sodium is lost. Loss of body fluids (vomiting, diarrhoea, etc.) may result in hypernatraemia, but in fact hyponatraemia is more often seen than hypernatraemia.Increase in sodium content of the ECFIncrease in sodium content of the ECFIn order to correct an acidosis ,sometimes high concentrated sodium bicarbonate(8.4%) is administrated to the patient. This may lead to hypernatraemia because sodium bicarbonate(8.4%) contains much more sodium than the physiological fluid. So, a less concentrated solution(1.26%) is preferred to correct an acidosis.Clinical featuresClinical featuresThe clinical features associated with the hypernatraemia are variable. If there has been fluid loss, then the features of dehydration may be present.(see page 12) In the case of salt gain, there may be indications of fluid overload (raised jugular venous pressure , pulmonary oedema). Decreased skin turgor(充实度) Decreased skin turgor(充实度)This sign is frequently unreliable in the elderly, who have reduced skin elasticity(弹性). In the young it is a sign of severe dehydration with fluid loss from the ECF.Treatment of hypernatraemiaTreatment of hypernatraemiaThe patient should be given water orally if possible. If not, then 5% dextrose can be given intravenously.Case history 5Case history 5A 76-year-old man with depression and very severe incapacitating disease was admitted as an acute emergency. He was clinically dehydrated. His skin was lax and his lips and tongue were dry and shrivelled looking. His pulse was 104/min, and his blood pressure was 95/65 mmHg. The following biochemical results were obtained on admission: Na+ K+ Cl- HCO3- Urea Creatinine --------------------------------mmol/l------------------------------------- mol/l 3.6 132 18 22.9 155 Comment on these biochemical findings. HypernatraemiaHypernatraemiaHypernatraemia is most commonly due to water loss(e.g. because of continuing insensible losses in the patient who is unable to drink) Failure to retain water as a result of impaired AVP secretion or action may cause hypernatraemia Hypernatraemia may be the result of a loss of both sodium and water as a consequence of an osmotic diuresis e.g., in diabetic ketoacidosis. Excessive sodium intake, particularly from the use of intravenous solutions, may cause hypernatraemia. Rarely, primary hyperaldosteronism(Conn’s syndrome) may be the cause. A high plasma osmolality may be due to the presence of glucose, urea or ethanol, rather than sodium(in other osmolaity disorders) Hyponatraemia 1.Hyponatraemia is significant fall in serum sodium concentration below the reference range of 130 mmol/l. 2.Causes: retention of water. Sodium loss Hyponatraemia 1.Hyponatraemia is significant fall in serum sodium concentration below the reference range of 130 mmol/l. 2.Causes: retention of water. Sodium loss Water tank model of hyponatraemiaWater tank model of hyponatraemia(a) Water retention throughout ECF and ICF. (b) Sodium lossHyponatraemia with water retentionHyponatraemia with water retention non-oedematous hyponatraemia oedematous hyponatraemiaNon-oedematous hyponatraemia(1)Non-oedematous hyponatraemia(1)This type of patients exhibit the features of the SIADA抗利尿激素异常分泌综合征 They are hyponatraemic, normotensive, have normal GFR [glomerular filtration rate]肾小球滤过率 and serum urea and creatinine concentration. The SIADA is encountered in many conditions: Infections Malignancy Trauma Drug-induced Patients suffering any of the above have non-osmotic AVP stimulation. . Non-oedematous hyponatraemia(2)Non-oedematous hyponatraemia(2)Non-osmotic stimuli can cause huge increases in AVP content. These stimuli include: 1.Reduction in the circulation volume/hypotension 2.Nausea and vomiting 3.Hypoglycaemia 4.Pain The non-osmotic regulation of AVP overrides the osmotic regulatory mechanism and this results in water retention which is a non-specific feature of illness.Clinical featuresClinical featuresFor patients whose syndrome develops over a long period, they may be asymptomatic. For acute patients, they will be shown with neurological symptoms(confusion, convulsions, coma, etc.) Treatment of non-oedematous hyponatraemiaTreatment of non-oedematous hyponatraemiawith asymptomatic patients, just reduce fluid intake to less than 750 ml/day. With patients of neurological symptoms, the cautious use of hypertonic saline should be considered to correct the hyponatraemia. Oedematous hyponatraemiaOedematous hyponatraemiaThe principal causes of oedema are heart failure and hypoalbuminaemia. Patients who have generalized oedema have an increase in both total body sodium and water, but have a reduced effective blood volume. The reduced effective blood volume stimulates the secretion of aldosterone and the AVP. So water is retained.The development of hyponatraemia in the oedematous patient The development of hyponatraemia in the oedematous patient Clinical featuresClinical featuresPitting oedema For ambulant patients, look for pitting in the lower extremities. For recumbent patients, look for pitting in the sacral area.Pitting oedemaPitting oedemaAfter depressing the skin firmly for a few seconds an indentation or pit is seen.Treatment of oedematous hyponatraemiaTreatment of oedematous hyponatraemiaThe underlying condition should be treated. Excess sodium and water should be reduced by means of a diuretic and by fluid restriction.Hyponatraemia: water retentionHyponatraemia: water retentionHyponatraemia because of water retention is the commonest biochemical disturbance encountered in clinical practice. In many patients the non-osmotic regulation of AVP overrides the osmotic regulatory mechanism and this results in water retention which is a non-specific feature of illness. Hyponatraemic patients without oedema, who have normal serum and creatinine and blood pressure, have water overloaded. This may be treated by fluid restriction. Hyponatraemia patients with oedema are likely to have both water and sodium overload. These patients may be treated with diuretics and fluid restriction. Hyponatraemia --- due to sodium loss: Gastrointestinal loss (severe and prolonged vomitting, diarrhoea, fistula) Urinary loss (aldosterone deficiency,drugs antagonizing aldosterone action) loss from the skin Hyponatraemia --- due to sodium loss: Gastrointestinal loss (severe and prolonged vomitting, diarrhoea, fistula) Urinary loss (aldosterone deficiency,drugs antagonizing aldosterone action) loss from the skin Fig The causes of hyponatraemia due to water retentionFig The causes of hyponatraemia due to water retentionClicical featuresClicical featuresPatients with hyponatraemia due to sodium loss, will be shown with clinical signs of ECF depletion. Of the clinical signs of ECF depletion, the most important are hypotension and tachycardia (especially in the recumbent state ).nullThe clinical features of ECF compartment depletionTreatment Treatment Treatment is based upon two principles: Correction of the sodium loss(0.9%NaCl iv,oral salt tablets) Treatment of the underlying disorder(steroid therapy, surgical treatment)ECF DEPLETION—A NOTE OF CAUTION (effective blood volume reduced) Water tank models show that reduced ECF volume may be associated with reduced, increased or normal serum[Na]+ECF DEPLETION—A NOTE OF CAUTION (effective blood volume reduced) Water tank models show that reduced ECF volume may be associated with reduced, increased or normal serum[Na]+PseudohyponatraemiaPseudohyponatraemiaHyponatraemia :sodium lossHyponatraemia :sodium lossHyponatraemia may occur in the patient with gastrointestinal or renal fluid losses which have caused sodium depletion. The low sodium concentration in serum occurs because water retention is stimulated by increased AVP secretion. Patients with hyponatraemia because of sodium depletion show clinical signs of fluid loss such as hypotension. They do not have oedema. Treatment of hyponatraemia, due to sodium depletion, should be with sodium and water replacement,preferably orally. POTASSIUM DISORDERS The concentration of potassium in serum is around 4mmol/l. Word and VocabularyWord and VocabularyIngest cellular reciprocal 相互的，交感神经的 Electroneutrality 电中性 hypokalaemia 低血钾 potential 电势，电位，潜在的 Excitable 易激的 hyperkalaemic 高血钾的 para esthesiae 感觉异常Herald n.先锋 v.预报 redistribution 再分布 trauma n.外伤 Rhabdomyolysis n. 横纹肌溶解 artefactually 人为地 haemolysis 溶血 Arrhythmia 心律不齐 cardiac arrest 心脏停搏 asymptomatic 无征兆的 insulin 胰岛素 corticosteroid 皮质类固醇 antagonist 拮抗剂 digoxin 地高辛 Priority 优先 Potassium balancePotassium balanceGlomerular filtrationSERUM POTASSIUMSERUM POTASSIUMSerum potassium is much less compared with that in the ICF. Factors which cause a small or sudden shift of ICF potassium will cause a big change in the ECF content . Cellular uptake of potassium is stimulated by insulin. Potassium and hydro