APPROACH TO FLUID , ELECTROLYTES AND ACID BASE DISORDERS DR.S.SHIVAKUMAR PROF.OF.MEDICINE STANLEY MEDICAL COLLEGE & HOSPITAL

INTRODUCTION: Hyponatremia is a very common disorder Fluid & Electrolytes can occur as single or multiple disorders Hyponatremia is a very common disorder Pottassium disorders can be life threatening Acid base disorders common in ICU & medical wards Choice of fluid therapy should be appropriate Treat individual disorders, but should be combined in multiple disorders.

APPROACH: Acidosis Alkalosis Disorders of volume - Volume depletion - Fluid overload Dysnatremia - Hyponatremia / Hypernatremia Dyskalemia - Hypokalemia / Hyperkalemia Acid base disorders Acidosis Alkalosis Metabolic/ Respiratory Metabolic / Respiratory

CLINICAL APPROACH: CLINICAL FEATURES: Volume depletion ------- Skin turgor loss / Hypotension Volume excess -------- Oedema / HT Hyponatremia/ Hypernatremia ------ CNS Manifestations Hypokalemia ----- Muscle weakness Hyperkalemia ---- Cardiac arrythmias Metabolic acidosis Respiratory alkalosis Hyperventilation

+ - MULTIPLE DISORDERS: Disorder DKA Diarrhea ARF Diuretics Volume Na+ M.Acidosis + - M.Alkalosis

SINGLE DISORDERS: Disorder SIADH Methanol poisoning Periodic paralysis Volume N Na+ K+ ABG Acidosis

FLUID & ELECTROLYTE HOMEOSTASIS Regulation of Volume (Na+) Na+ GFR Renin Angiotensin Aldosterone Renal retention of Na+ ECF Volume is regulated by Na.( BP & Interstitial volume) 2.Regulation of Osmolality ( Water) H2O Osm ADH Kidney retains H2O ICF Volume is regulated by osmolarity of plasma. Normal plasma osmolarity = 285-300 mOsm/L Calculation= 2(Na + K)+ Sugar/18+Urea/6 Ratio of Na+ to H2O decides plasma osmolality. 3.Regulation of Acid Base:

VOLUME & OSMOLALITY DISORDERS: Volume Disorders: Only clinical signs (PNa+- Normal) Volume depletion ---- ECF Na+ loss ( Diarrhea,Diuretics ) Volume excess ----- Na Retention( Cardiac failure, renal failure) Osmolar Disorders:- Plasma Na+ altered. 1. Water Excess ---- Hyponatremia (SIADH) 2.Water depletion -- Hypernatremia ( D.Insipidus ) Volume & Osmolar Disorders: (Clinical & Altered P. Na+) Volume depletion & Water excess – ECF Na loss & H2O retention / Hyponatremia ( Diarrhea & 5%GDW) Volume depletion & excess water depletion - Na < H2O loss / Hypernatremia (HONK )

20% (ECF) 40% (ICF) Normal Total body sodium determines ECF Volume. INTRACELLULAR VASCULAR (4%) Interstitial (16%) Total body sodium determines ECF Volume. Plasma Na determines ICF volume. Plasma osmolarity (PNa+) determines fluid movement into cell.

Volume depletion (ECF ) Normal PNa+ INTRACELLULAR Loss of skin turgor Hypotension 40% 10% Eg: Diarrhea, Vomiting & Diuretics Total body Na loss leads ECF volume depletion. No change in plasma Na.

Volume excess (ECF ) 30% 40% edema HT Normal PNa+ 30% 40% edema INTRACELLULAR HT Eg: Cardiac failure,Nephrotic syndrome, Renal failure & Cirrhosis Increased total body Na leads to ECF volume excess. Plasma Na normal

Hyponatremia (ICF ) 45 % 20% Eg: SIADH INTRACELLULAR PNa+ 20% Eg: SIADH Increased ADH Increased total body H2O leads to decreased plasma Na ( Osmolarity ) Increased ICF due to shift of H2O from ECF to ICF.

Hypernatremia (ICF ) 20% 30% PNa Eg: D.Insipidus INTRACELLULAR Eg: D.Insipidus Polyuria Pure water depletion Decreased body H2O leads to increased plasma Na ( Osmolarity) H2O shifts from ICF to ECF.

Volume depletion & Hyponatremia (ECF & ICF ) 45 % Hypotension, skin turgor loss, Drowsiness INTRACELLULAR H2O PNa 10 % Na + Eg: Diarrhea, replaced by 5 % GDW Total body Na decreased by Diarrhea Increasaed H2O retention due to 5 % GDW ( Plasma Na low) ECF volume depletion + Increased ICF volume

Volume excess & Hyponatremia ( ECF & ICF ) 25 % 45 % INTRACELLULAR H2O edema & P Na + Eg: Cirrhosis + 5 % GDW Cirrhosis leads to increased total body Na & ECF Excess H2O leads to decreased plasma Na & increased ICF

30 % 10% Volume depletion & Hyperosmolarity ( ECF & ICF ) Osmolarity INTRACELLULAR Osmolarity Na+ H2O Eg: Hyperosmolar Non- Ketotic syndrome ( DM) Polyuria of DM leads to ECF volume depletion ( H2O> Na) Increased plasma Glucose leads to hyperosmolarity & ICF depletion Plasma Na can be Normal OR High ( Instead of being low)

Why do we need fluids? FLUIDS --- Healthy individuals Sick patients: ---Regulation of temperature --- loss by sweating ---Excretion of waste products -- Renal / GI 1.5 – 2.5 L / Day Salt – 5 gm / day Sick patients: 1.Replacement for losses --- GI losses – Vomiting / Diarrhea --Renal losses -- DKA / Diuretics -- Skin loss – Burns / sweating 2.Maintenance --- for daily requirements

Concentration of ions in IVF (In Meq/L) Solutions Glucose(gms) Na Cl K Ca Lactate 5%GDW 50 10%GDW 100 20%GDW 200 5%GDW/0.9%NaCl 154 5%GDW/0.45NaCl 77 0.45%NaCl 0.9%NaCl 3%NaCl 513 RL 130 109 4 3 28

Concentration of ions in IVF (Poly-ionic fluids) Solutions Na K Cl Glucose Na K Cl Acetate HPO4 NH4 Isolyte-M 50 40 35 20 15 Isolyte-E 140 10 103 47 Isolyte-G 63 17 150 70

DISORDERS OF VOLUME

Volume depletion Isotonic volume depletion Diarrhea Vomiting Hypotonic volume depletion Hypertonic volume depletion Diarrhea replaced by H2O D.Insipidus HONK DKA Excess sweating PNa H2O > Na loss PNa-Normal Na+ = H2O loss PNa H2O < Na loss

Correction: Body weight: Volume depletion: 0 - 8 hrs Choice of fluids: ISOTONIC VOLUME DEPLETION: Causes - vomiting / Diarrhea Assess severity - mild / moderate / severe Body weight: 5 %- mild : skin turgor loss / dry Tongue 5 % - 10 % : Mild + postural hypotension 10 % - severe: moderate + hypotension Correction: Volume depletion: 0 - 8 hrs 0- 1 hrs --- shock 1- 8 hrs -- rest of calculated fluids 8- 24 hrs -- maintanance fluids & concurrent losses Choice of fluids: Diarrhea --- RL Vomiting - 0.9 % NaCl

A 50 year old male is admitted for severe diarrhea of 3 days duration A 50 year old male is admitted for severe diarrhea of 3 days duration. He is drowsy & has loss of skin turgor & dry mouth. BP: 80 / 50 mmHg.Lungs are clear. Urea : 72 mg% S.Cr : 1.7 mg% Na+ : 122 meq/L K+ : 2.6 mg% Ph: 7.2 pCo2 : 32mmHg pO2 : 100 mmHg HCO3 :12 mmHg Problems: Severe volume depletion Hyponatremia Hypokalemia Metabolic acidosis Azotemia- prerenal

50 year Individual ( 50 kg) Severe Volume depletion - 10 % - 5 L Diarrhea – Na, K, HCO3 loss Replacement fluids - RL 0-1 hr – 1 L ( Treatment of Shock) 1- 8 hr – 4 L Maintanence fluid + concurrent loss : 1.5 – 2.5 L ( 8- 24 Hrs) Decreased Na – Corrected by Volume correction RL – Lactate HCO3 in liver

Treatment -- HONK / DKA – 0.45 % NaCl D.Insipidus ---- 5 % GDW Hypertonic volume depletion ( Volume depletion & water depletion - PNa ) Na < H2O Depletion Pure H2O depletion Extrarenal Insensible losses Renal DI NDI Extra renal ( sweating) Esp.pt not taking oral fluids Renal loss DKA HONK Salt losing nephritis Treatment -- HONK / DKA – 0.45 % NaCl -- 0.9 % NaCl + 5 % GDW D.Insipidus ---- 5 % GDW

DYSNATREMIAS

Hyponatremia Hypovolemia Euvolemia Hypervolemia Diuretics Diarrhea Post-operative SIADH Drugs CNS & Pulmonary diseases (Menstruating women) CCF Nephrotic syndrome Cirrhosis

Hyponatremia Symptoms: Symptomatic Asymptomatic Chronic ( > 48 hrs) Acute < 48 hrs Symptoms: CNS: Cerebral edema -- Headache, Drowsy / coma / Seizures. Lab: PNa < 135 meq/L

Management Symptomatic Hyponatremia Treatment: Emergency: 3 % NaCl 1- 2 ml/ kg/ hr with co-administration of Furosemide STRATEGY: Removal of H2O Furosemide: Natriuresis -- Na + H2O Replace Na with 3 % NaCl – Excretion of H2O Urine output > fluid intake

Treatment objectives: Asymptomatic Hyponatremia: ( Euvolemia& Hypervolemia) 1.Water restriction : < 1L / day 2.Demeclocycline -- 300 – 600 mg / day 3.Identify & treat the causes Hypovolemic Hyponatremia: IV Fluids -- NaCl / RL Treatment objectives: Gradual correction of PNa Perform serial neurological examination Perform serial Serum Na & Urine Electrolytes & osmolality

A 60 year old male a known case of Bronchogenic carcinoma is admitted for seizures. He is unconscious & his volume is normal Urea : 28 mg % S.Cr : 0.8 mg % Na+ : 110 meq/L K+ : 4.6 meq/L Ph: 7.4 Pco2 :40mmHg HCO3: 24 mmHg PROBLEMS: 1.Volume status -- normal 2. Na+ -- Hyponatremia ( Euvolemia) 3. K+ --Normal 4. ABG-- Normal TREATMENT: 3 % Saline & Furosemide

Clinical features : CNS Manifestations HYPERNATREMIA Hypovolemic hypernatremia Hypervolemic hypernatremia Euvolemic hypernatremia DKA,HONK Excess sweating Decreased fluid intake Peritoneal dialysis (Hypertonic fluids) Diabetes Insipidus Clinical features : CNS Manifestations Lab: PNa > 150 meq/L

Treatment: Hypovolemic Hypernatremia : -- 0.45 % NaCl -- 5 % GDW -- Oral fluids Euvolemic Hypernatremia: 5 % GDW Oral fluids Hypervolemic Hypernatremia: Dialysis

DYSKALEMIAS

Hypokalemia : K + < 3.5 meq/ L Causes Metabolic alkalosis Vomiting Diuretics Normal Ph -Periodic paralysis Metabolic acidosis Diarrhea RTA Treatment of DKA Diagnosis: Serum K+ : 3 – 3.5 meq/L - Mild 2.5 – 2.9 meq/L – Moderate < 2.5 meq/L -severe

Complications: Muscle weakness -Respiratory failure Cardiac arrhythmias Hepatic encephalopathy Paralytic ileus

TREATMENT: Non- urgent situations: Not to exceed 10 meq/hr IV KCl : 15 % solution 1 cc = 2 meq/L Add to 0.9 % NaCl solution KCl 10 ml = 20 meq/L 20 ml = 40 meq/L Non- urgent situations: Not to exceed 10 meq/hr In urgent situations: 40meq/Hr Oral solution: 10 % KCl solution ( 15 ml =20 meq/L) --- Diluted in juice 80 – 120 ml / day KCl should be given for 10 – 14 days

HYPERKALEMIA: Causes: Management: Renal failure Drugs -- ACE Inhibitors, Beta-bockers, spironolactone Diagnosis: 1. ECG , 2. Serum K+ Measurement ( > 5 meq/L) Management: 1. Calcium Gluconate: 10- 30 ml of 10 % solution, acts immediately, action lasts for only 30 mts 2. Insulin- 10 units / Glucose – 50 gms, acts in 15 – 30 Mts, effective for several hours 3. Sodium Bicarbonate: 50 – 150 ml of 7.5 % NaHCO3 4.Cation ion exchange resins: Na.Polysterene sulphonate (oral/enema) 5. Dialysis

ACID BASE DISORDERS

ABG Disorders: Diagnosis – Ph, HCO3, Pco2 1. Check validity 2. Obtain minimal diagnosis 3. Is it a single or mixed ABG disorder 4. Determine Anion Gap 5.Is it a triple ABG Disorder

Obtain minimum diagnosis Look at pH - Acidosis / Alkalosis Match the Pco2 or Hco3 - Metabolic / Respiratory Disorder Primary Change Secondary change Net effect M. Acidosis  Hco3  Pco2  pH ( H+) M.Alkalosis  Hco3  Pco2  pH ( H+) R. Acidosis R. Alkalosis

Examples of Simple Disorder pH Hco3 Pco2 Metabolic Acidosis 7.15 8 24 Respiratory Acidosis 30 90 Metabolic Alkalosis 7.7 36 48 Respiratory Alkalosis 12 10

Is it a simple or mixed Acid-base disorder? Simple Disorder : Disorder Example Metabolic acidosis DKA, Renal failure, Lactic acidosis, Methanol poisoning, Diarrhea,RTA Metabolic alkalosis Vomiting, Diuretics, Steroids Respiratory acidosis COPD Respiratory alkalosis Psychogenic hyperventilation, Hepatic Encephalopathy

Mixed Disorder Situation Disorder Respiratory acidosis COPD + Vomiting + Metabolic alkalosis COPD + Diarrhea + Metabolic acidosis Sepsis Metabolic acidosis + Respiratory alkalosis Cirrhosis + Diuretics Respiratory alkalosis

Apply Compensation Metabolic Acidosis Pco2 should  by 1.2 mm for each 1 mEq  plasma Hco3 Metabolic Alkalosis Pco2 should  by 0.6 mm for each 1 mEq  plasma Hco3 Acute Resp.Acidosis Plasma Hco3  by 1 mEq / L for each 10 mm  Pco2 Chronic. Resp. Acidosis Plasma Hco3  by 4 mEq / L Acute. Resp. Alkalosis Plasma Hco3  by 1 mEq / L for each 10 mm  Pco2 Chronic Resp Alkalosis Plasma Hco3  by 4 mEq / L

Example – COPD & Diarrhea pH : 7.00 Pco2 = 32 Hco3  = 8 Fall in Hco3 = 24 – 8 = 16 Compensatory Fall in Pco2 = 16 x 1.2 = 19 Anticipated Pco2 = 40 – 19 = 21 Estimated : Pco2 = 32 (Pco2  ) Diagnosis Mixed - Metabolic acidosis + Respiratory acidosis

Mixed acid base disorder Compensation PH Metabolic Acidosis + Respiratory Acidosis eg: COPD + DKA PCo2  & Hco3  for simple disturbance pH = PCo2  Hco3  Metabolic Alkalosis+ Respiratory Alkalosis eg: Cirrhosis + Diuretics PCo2  & Hco3  pH = PCo2  Hco3 

Mixed acid base disorder Compensation PH Metabolic acidosis + Respiratory alkalosis eg : Sepsis PCo2  & Hco3  for simple disturbance Normal or slightly  or  (N) pH = PCo2  Hco3  Metabolic alkalosis + Respiratory acidosis PCo2 & Hco3  (N) pH = PCo2  Hco3 

Examples of mixed acid base disorder Data Disorder pH Hco3 Pco2 Po2 6.85 15 (30) 90 50 Respiratory acidosis + Metabolic acidosis 7.3 45 (30) + Metabolic alkalosis 6 12 (22) 100 Metabolic acidosis + Respiratory alkalosis 7.75 40 25 (43) Metabolic alkalosis

Determine the Anion gap AG = Na+– (Hco3  + Cl ) Normal = 12 ± 4 ( 8  16 ) Valuable in Metabolic acidosis – High gap / Normal gap Metabolic alkalosis – Evaluation of “Starting Hco3” High gap acidosis : AG > 27 mEq /L 17  26 Suggestive eg. – Ketoacidosis, Lactic acidosis, Methanol intoxication, Renal failure Normal gap acidosis – Diarrhea, RTA

AG in metabolic alkalosis Valuable in diagnosis of Triple disorder (Metabolic acidosis,Met.alkalosis & Resp. acidosis) Delta () AG = Calculated Anion gap – Normal Anion gap Hco3 +AG = Starting Hco3 Starting Hco3 > 29 suggests associated Metabolic Alkalosis in the presence of Metabolic Acidosis

Example Na+ = 135 Hco3 = 4 cl  = 90 pH = 6.8 AG = Na  ( Hco3  + cl ) = 135 – (4 + 90) = 41  High gap acidosis AG = Calculated – AG Normal = 41 – 12 = 29 Starting Hco3 = 4 + 29 = 33 mEq / L Starting Hco3 > 29 suggests associated Metabolic Alkalosis in the presence of Metabolic Acidosis

Approach with an Example A 50 year old male suffering from COPD & vomiting is admitted for breathlessness. Biochemical parameters pH – 6.8 pCo2 - 22 pO2 - 60 Hco3- 3.4 Na+ 135 k – 6.0 Cl- - 90 urea-110 S.Cr. – 3.0 sugar-100

pH = 6.8 Pco2 = 22 Hco3 = 3.4 Step 2: Obtain minimum diagnosis Step 1 : Check Validity H = 24 X Pc02 = 24 X 22 = 155 nEq / L = pH(6.8) HCo3 3.4 Step 2: Obtain minimum diagnosis pH = 6.8 Pco2 = 22 Hco3 = 3.4  Metabolic acidosis

Estimating the H+ ion from pH 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 100 80 62 50 40 32 25 20 16  1.25 X 0.8 Within narrow limits 0.01 change in pH ~ 1 mEq / L change of [H+] 7.40 = 40 7.39 = 41 7.38 = 42 7.37 = 43

pH = 6.8 Pco2 = 22 Hco3 = 3.4 Step 3: Is it a Simple or Mixed Acid base disturbance By applying compensation (24  3.4 = 20.6 ; 20.6  1.2 = 24.7; 40  24.7 = 15.3) Predicted Pco2 = 15.3, but Observed Pco2 = 22 Mixed disorder Metabolic Acidosis + Respiratory Acidosis

pH = 6.8 Pco2 = 22 Hco3 = 3.4 Determine Anion Gap Step 4: Na = 135 Cl = 90 Hco3 = 3.4 AG = 135 – (3.4 + 90) = 41.6 High Gap acidosis

pH = 6.8 Pco2 = 22 Hco3 = 3.4 Is it a triple disorder Step 5: Is it a triple disorder Look for metabolic acidosis with AG AG = Calculated AG - AG normal = 41.6 - 12.0 = 29.6 Starting Hc03 = Hco3+ AG = 3.4 + 29.6 = 33 mEq /L (Metabolic alkalosis)

Diagnosis Triple Disorder = Metabolic acidosis + pH = 6.8 Pco2 = 22 Hco3  = 3.4 Po2 = 60 Na+ = 135 k + = 6.0 Cl = 90 Urea= 110 S.Cr = 3mg/dl Sugar = 100 mgs Triple Disorder = Metabolic acidosis + Resp.acidosis + Met.alkalosis Metabolic acidosis – Renal failure Respiratory acidosis – COPD Metabolic alkalosis – Vomiting

Example –1 A 40 yr old man is admitted for diarrhea & breathlessness for 2 days. pH - 7.2 pCo2 - 32 pO2 - 100 Hco3- 12 Na+ - 138 k - 2.9 Cl- - 115 urea-70 S.Cr. - 1.4 sugar-110 Diagnosis: Normal AG Met.Acidosis (AG – 11) Due to Diarrhea + Hypokalemia,

Example –2 Due to Renal failure + Hyperkalemia A 40 yr old man is admitted for diarrhea of 1week & breathlesness of 1 day pH - 7.1 pCo2 - 20 pO2 - 100 Hco3- 6 Na+ - 140 k + - 6.9 Cl- - 105 urea-120 S.Cr. - 5.4 sugar-110 Diagnosis: High gap Acidosis (AG - 29) Due to Renal failure + Hyperkalemia

EXAMPLE 1: TREATMENT b)Dialysis CONSERVATIVE MANAGEMENT IVF- RL (OR) IV Saline ( 400 ml) + 75 ml NaCO3 + 10 ml KCl EXAMPLE 2: a)Treat Hyperkalemia b)Dialysis

Example –3 (Predicted pCo2 – 18, but observed pCo2 – 12) A 45 yr old female is admitted for high fever & breathlessness, diagnosed to have acute Cholecystitis pH - 7.3 pCo2 - 12 pO2 - 100 Hco3- - 6 Na+ - 140 K+ - 5 Cl - - 105 Urea-45 S.Cr. - 1.6 Sugar-120 (Predicted pCo2 – 18, but observed pCo2 – 12) Diagnosis: Metabolic acidosis + Respiratory Alkalosis Due to sepsis TREATMENT: Treat Sepsis

Example –4 A 50 yr old Pt., a known case of COPD is admitted for severe diarrhea pH - 6.9 pCo2 - 40 pO2 - 50 Hco3- 9 Na+ - 140 K+ - 4 Cl- - 105 Urea-45 S.Cr. - 1.2 Sugar - 128 (Predicted pCo2 – 25, but observed pCo2 – 40) Diagnosis: Respiratory Acidosis (COPD ) + Metabolic acidosis (Diarrhea)

Example –5 A 50 yr old, known COPD Pt. with Cor pulmonale on treatment with Frusemide and is admitted for severe vomiting. pH - 7.4 pCo2 - 80 pO2 - 40 Hco3- -48 Na+ - 140 K+ - 2.8 Cl- - 105 Urea-45 S.Cr. - 1.2 Sugar- 128 (Predicted pCo2 – 54, but observed pCo2 – 80) Diagnosis: Respiratory Acidosis (COPD ) + Metabolic Alkalosis (Vomiting + Diuretics)

EXAMPLE 4: Ph-6.9 – Lifethreatening Acidosis Metabolic Acidosis – IV NaCo3 To raise HCO3 Respiratory acidosis- Ventilatory Support To lower PCO2 EXAMPLE 5: Ph – 7.4 Treat conservatively Metabolic Alkalosis- IV Saline + KCl Stop Diuretics Respiratory Acidosis – O2 Therapy - Ventilatory support

Example –6 A 50 yr old Pt. with Cirrhosis Liver is admitted for coma & Vomiting. He has been treated with Frusemide recently for ascites. pH - 7.75 pCo2 - 30 pO2 - 80 Hco3- - 40 Na+ - 135 K+ - 2.4 Cl- - 95 Urea - 45 S.Cr. - 1.2 Sugar -110 (Predicted Hco3 – 20, but observed Hco3 – 40) Diagnosis: Respiratory Alkalosis (Cirrhosis ) + Metabolic Alkalosis (Vomiting + Diuretics) TREATMENT: Stop Diuretics + IV Saline with KCl Treat Hepatic Encephalopathy

Summary Suspect the diagnosis from history Suspect the disturbance from physical symptoms Assess volume status to determine fluid therapy Determine P.Sodium to determine water intake Measure K+ levels & Utilize ECG to determine cardiac effects

Evaluate routine laboratory date : Sugar, RFT, LFT, Na+, K+ Establish the cause of Acid Base disorder (Utilize thoughtful differential diagnosis) Direct management of underlying disorder, unless pH is in a dangerous range

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