Potassium Disorders

Preface: normal metabolism of potassium 1. normal serum potassium: 3.5-5.5mmol/L 2. distribution of potassium ICF:98% (muscle:75%) ECF: 2% 3. balance between intra- and extracellular K+ normal: 15 h 4. intake and loss of potassium intake: food; loss: urine; feces; sweat

5. influencing facter of potassium homeostasis acidosis alkalosis hypoxia serum insulin serum damage of cells [K+] ADS [K+] catabolism anabolism distal flow rate distal flow rate

concept: serum potassium＜3.5mmol/L I. Hypokalemia concept: serum potassium＜3.5mmol/L 1.  cause and pathogenesis ①  intake fast alkalosis injection of insulin ② move into Barium poisoning cells hypokalemic periodic paralysis

GI: vomiting; diarrhea; Gastrointestinal suction Skin: excessive sweats furosemide diuretic ③ losses diamox diuretic phase of ARF ren: pyelonephritis primary hyperaldosteronism lack of magnesium renal tubular acidosis

3. effect on body 1) nerves and muscles excitability 0 mv serum[K+] -30mv AP -60mv TP(Et) -90mv RP(Em) hyperpolarization

2) heart arrhythmia 0 mv serum[K+] -30mv -60mv -90mv depolarization

[K+]ECF K+ permeability depolarization Excitability: [K+]ECF K+ permeability depolarization repolarization excitability ECG T wave Conductivity: RP 0 phase of AP   conductivity conductive block unidirectional block ECG P-R

血浓缩 Autorhythmicity: Contractility: acute ; chronic ③ Ren polyuria (sensitivity of ADH ) ④ GI smooth muscles (hyperpolarization) ⑤ acid-base balance (metabolic alkalosis)  4. principles of treatment supply potassium 口服最好。原则：见尿补钾。 血浓缩 anuria 不排钾 补钾速度：10-20mmol/h 可能有酸中毒 补钾浓度：20-40mmol/L

病例8：患者，女性，22岁，因结核性腹膜炎和肠梗阻进行手术，术后行持续胃肠减压7天，共抽吸液体2200ml。平均每天静脉补液（5%葡萄糖液）2500ml。尿量2000ml。术后2周，患者精神不振，全身乏力，面无表情，嗜睡，食欲减低，腱反射迟钝。 实验室检查：血K+ 2.4mmol/L,血Na+140mmol/L，血Cl- 103mmol/L。 辅助检查：ECG显示，Ⅱ、aVF、V1、V5导联ST段下降，aVF导联T波双向，V3 有u波。 立即开始每日以KCl加入5%葡萄糖滴注，四天后血K+升至 4.6mmol/L，上述表现恢复正常。

Concept: serum [K+]＞5.5mmol/L II . Hyperkalemia Concept: serum [K+]＞5.5mmol/L 1. cause and pathogenesis acute renal failure chronic renal failure GFR ① loss of shock potassium Addison’s disease 抗醛固酮利尿药(antisterone)

 ②  K+ move out of cells Acidosis; hypoxia; hemolysis; crush syndrome; 高钾血症型周期性麻痹       ③ intake of 10% KCl potassium penicillin potassium transfusion of bank blood 2.   effects on body ①   skeletal muscle ＜8mmol/L RP (depolarization) excitability stabbing; tremor ＞8mmol/L RP inactivation of Na+ channel depolarization paralysis

② heart (hyperkalemia K+ permeability ) 5.5-7mmol/L→ RP → E excitability 7-9mmol/L→ RP → E T wave ; QT short cardiac arrest PR QT

Autorhythmicity: K+ out ward of phase 4 Spontaneous depolarization heart rate Conductivity: RP Na+ inward of phase 0 conductivity conductive block unidirectional block Contractility : inhibition of Ca2+ inward flow contractility ③ acid-base balance

3.   principles of treatment ①  transfusion of insulin and glucose ②  transfusion of sodium bicarbonate ③  transfusion of calcium

病例9：患者，女性，因大面积烧伤和严重呼吸道烧伤入院。 体格检查：头面及胸腹部烧伤，面积约占85%经处理病情比较稳定。第28天发现创面感染，随后患者体温39℃，血细菌培养阳性，血压降至70/50mmHg，尿量400ml/d，Ph7.088，HCO-3 9.8mmol/L。PaCO2 33.4mmHg，血K+ 6.8mmol/L,血Na+ 132mmol/L，血Cl- 102mmol/L。 心电图显示：P波和QRS波振幅降低，QRS波增宽，S波增深，T波高尖。经积极救治，病情仍无好转，于第33天时引发心室纤颤和心脏停搏死亡。