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Fluid and Electrolyte Disturbances in Clinical Practice

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1 Fluid and Electrolyte Disturbances in Clinical Practice
B.U. Ahmadu

2 Fluid and Electrolyte Introduction Water Electrolyte imbalance
Acid –Base disorders

3 4-5 deaths due to dehydration
15-30 million cases of diarrhoea with rotavirus accounting for 35% with an estimated 500,000 deaths per year worldwide. 2-3 billion dollars in health care cost

4 Basic physiology Water largest single component of the body
Total body water approx 75-80% of body wt at birth & decreases with age. TBW – divided into 2 main compartments a, ICF (30-40%) b, ECF (20-25%) –plasma (5%) - interstitial (15%) * trancellular (2%) - GI secretns, urine, CSF,pleural, peritonial, synovial

5 Age and TBW Age Body water(%) ECF (%) ICF(%) Term baby 75 35-44 33
4-6 months 60 23 37 12 months 26-30 Puberty 20 40

6 Basic physiology contd
Obligatory water intake to prevent dehydration (1L/day) Metabolic water 1ml/kcal up to mls/day Obligatory water loss for solute excretion 500mls/day Steady state water intake (2.5L) = water output (2.5L) ≠ intoxication/dehydration

7 Osmoles/ Osmolarity / Osmolality/ Tonicity
Freezing / elevated boiling point technique Plasma Osmolality –concn of solute particles in plasma – mosm/kg/H2O 2Na + Glc + Urea (clinical 2Na) H2O is distributed b/w ICF & ECF according to amount of osmotically active solute in each compartment.

8 ECF solutes- Na+,Cl-,HCO3, glucose & urea
ICF solute - mainly K+ , Phosphates, proteins Other solutes-ethanol, mannitol, glycerol may contribute to an extent to plasma osmolality

9 Principal mechs regulating ECF vol
Osmotic Gap/ Solvent drag or compartmental steal phenomenon Water balance is controlled by regulating intake and excretion Sources of body H2O i, Intake. ii,Oxidation of CHO, fat & protein Mechs regulating ECF - Thirst; ADH; Aldosterone and atrial natriuretic factor( ANF)

10 Principal mechs regulating ECF vol
Body H2O loss routes – kidneys, lungs, skin & GI tract i, insensible loss (evaporative loss from lungs [2/3] & skin [1/3] – 40%, = 1 L ii, urine – 50-55%, = 1.3 L iii, Faecal loss – 5- 10% = 200mls Daily Electrolyte requirement: *Na, K, Cl = 2-3 mmol of each electrolyte/kg/dy

11 Calculating dly maintenance fluid
Body wt(kg) Kcal/kg ml of H2O/kg 3-10kg 100 11-20kg 1000kcal + 50kcal/kg for each kg >10kg 1000ml + 50ml/kg for each kg > 10kg >20kg 1500kcal + 20kcal/kg for each kg >20kg 1500ml + 20ml/kg for each kg > 20kg

12 Electrolyte Disturbance
Hyponatremia- Na <130meq/l -Causes –H2O retentn 2o to impaired excretn - Na loss exceeding H2O (thiazide), Cerebral Salt Wasting Syndrome (SSS) Signs & Symptoms- -Related to CNS- cerebral oedema Types -Hyperosmolar ↓ Na -( Serum Na <130; plasma osmol > 295) -Iso- osmolar ↓Na -( Serum Na < 130; plasma osmol ) -Hypo-osmolar ↓Na –( Serum Na < 130; plasma osmol<280)

13 Hyponatremia contd Hyperosmolar Causes – Hyperglycaemia; mannitol
Iso-osmolar Causes- hyperlipidemia, Hyperproteinemia Hypo-osmolar -hypovolemic- ↓total body Na & H2O *causes-renal loss . -GI loss, loss from skin & third space -Euvolemic- ± total body Na, ↑ total body H2O * causes-H2O intoxication, SIADH,pain, drugs, cortisol def, -hypothyroidism, CVA -hyprevolemic- ↑total body Na & H2O *causes- oedema forming states- CCF, cirrhosis,Nephrotic - acute & renal failure

14 Treatment of ↓Na Asymtomatic ↓Na: treat if Na < 120mmol/L
Symptomatic - any level of↓Na- -calculate meq Na reqd -( pts Na) x0.6 x wt -can use 3% saline -give at rate of 1ml/kg/hr ; not faster than 1meq/l/hr -Monitor Serum Na 2- 4hrly till stable Meq/day Treat Cause

15 Hypernatremia (serum Na>150)
Results from H2O loss in excess of solute OR Na retentn ↓volemic ↑Na -renal loss DI, DM, osmotic diuresis -extra renal loss skin ( burns, sweating,phototherapy, radiant warmer) Euvolemic ↑Na -causes –iatrogenic (IVF, or medicatns- Na valporate, voltaren) ↑ volemic ↑Na - causes –hypertonic salt solns,steroid excess, NaHCO3, Pry.hyperaldosteronism -

16 SIADH Inappropriate high secr of ADH in presence of concn urine
Causes: CNS disorders, Resp, Tumors, Drugs Labs: ↓serum Na,↑urine Na, ↑ Urine SG, ↓Urine output. Rx: Fluid Restriction - Lithium

17 Diabetes Insipidus Excessive flow of dilute urine 2o to lack of ADH secretn.(central) Or failure of kidney to respond to adequate amount of ADH (nephr) Causes: Central-1o (familial, non familial) 2o – Nephro- 1o (X linked or AR) 2 o renal dis, ↑Ca. Drugs( inhibit ADHsecr)- naloxone, ethanol, mannitol, Cytotoxic drugs, angiographic drugs Others- cleft lip/palate, familial Cerebellar ataxia

18 DI contd Diagnosis – water deprivation test Rx ↓volaemic ↑Na situation
Give fluids if in shock

19 SIADH vs DI Laboratory data SIADH DI Serum Na ≤130 ≥ 150
Urine Na ≥ ≤ 40 Serum osmol ≤ ≥ 305 Urine SG ≥ ≤ 1.005 Urine output (ml/kg/hr) < > 3 CVP ≥ high ≤ low

20 Hypokalaemia Causes ↓ intake: -vomiting, malnutrition,
GI loss:- diarrhea, N/G drainage, laxative abuse, fistula, colostomy,etc Renal loss: tubular diseases, Cushing’s syndrome, ↓ Mg, ↑aldosteronism, Bartter’s & Gittleman syndrome, distal RTA, Drugs –diuretic, amphotericin, NSAID. Skin loss: burns Redistribution: metabolic alkalosis from HCO3, insulin, B2 agonist

21 HYPOKALAEMIA Features- Weakness,paralysis, ↓reflex, ileus
- ECG changes- ST depr,flat T, u waves -enhances digoxin toxicity. Treatment Oral route preferred, may take 5-7dys *Rates of mmol/kg/hr considered safe. *IV fluid conc of ≤40mmol/l considered safe *If patient is in shock, commence K+ supplementation only when peripheral circulation is re-established and patient has also passed urine. * ECG monitor required *Correct underlying cause

22 HYPERKALAEMIA Features- Weakness, paralysis,parasthesia ↑PR interval, widened QRS, peaked T waves Treatment I,Treat cause, remove K from IVF OR diet If K+ >6.5 mmol/kg- needs immediate Rx a, Cacl(10%) ml/kg IV over mins antagonizes neuromuscular effects b, Insulin ( units/kg) & Glucose( 0.5-1g/kg) IV push and as infusion later. Max 10 units insulin -monitor glucose during infusion

23 Hyperkalaemia contd c, NaHCO4 (onset 3-4hr) - 1-2mmol/kg IV over 10-30min - Redistribute K from ECF to ICF d, Salbutamol neb- e, Kayexalate- 1g/kg (max 30g) po, ng, pr -onset 1 hr f, Dialysis if all else fails.

24 Hypocalcemia Total serum Ca= ionized Ca(40%), protein bound Ca (50%), and complexed (10%) Change in albumin of 1gm, changes Ca by 0.8mg Alkalosis↓ses ionized Ca, Acidosis ↑ses ionized Ca Causes- Bld Tx, Sepsis, alkalosis, ↓parathyroidism, Vit D def, Di George synd., Phenytoin, aminoglycosides, frusemide,glucocorticoid, HCO3, phenobarb Features- Muscle twitch, parasthesia,spasm, seizure, bradycardia, T-wave inversion,prolonged QT interval, Chvostek’s & Trousseau’s sign Treatment -Identify and Rx underlying cause. Give Ca

25 Hypercalcemia Causes- Malgnancy( 2o bone) ↑parathyroidism, granulomatous dis, vit D intoxicatn, thiaxide Features- weakness, anorexia,constipatn,vomiting, ↑BP, hypotonia, pseudotumour cerebri shortened QT interval, U waves

26 Hypercalcemia Treatment Identify and treat cause
Frusemide 1-2 mg/kg/d 4hrly Calcitonin -4unitd/kg –inhibits bone resorption Steroid esp if ↑Ca due to tumor, vit D toxicity or granulomatous disease- ↓ses gut Ca absorption Mithramycin – in ↑parathyroid or malignancy with 2o to bone meq/kg IV over 3-8hrs- ↓ses bone resorptn Dialysis with Ca free dialysate Bindind Ca with chelators and PO4 -associated with soft tissue depositn of Ca complexes - should be used as last resort -PO4 – mmol/kg IV over 6hrs

27 Fluid and Electrolyte disorders
Dehydration - depletion of body fluids -state of negative fluid balance that may be caused by a no of disease entities esp diarrhoea Types of dehydration Based on serum Na level or plasma osmolality Isonatraemic (isotonic) –Na meq/l Hyponatraemic (hypotonic) – Na- <130meq/l Hypernatraemic (hypertonic) – Na- >150 meq/l

28 Isonatraemic Dehydration
Most common (80%) Na+ and H2O losses are of the same amount in both intra & extra vascular compartments No osmotic gradient across cell membrane

29 Hyponatraemic Dehydration
Relatively more Na than H20 is lost from the body ECF is hypotonic relative to ICF, thus H20 shifts from ECF to ICF Can be caused by renal (diuretic use, renal salt wasting) Or extra-renal losses( i.e. thro GI, skin)

30 Hypernatraemic Dehydration
Relatively less Na than water is lost ECF volume is relatively preserved b/cos water moves from ICF space Pt appears less dehydrated for a given amount of TBW loss compared to isotonic dehydration

31 MANAGEMENT OBJECTIVES
Prevent dehyration (ORS, Fluids) Correct dehydration (Litres) (135-pts Na) x 0.6 x wt 135 Maintain or improve nutrition Treat aetiological agents if any

32 HIGH RISK FACTORS FOR DEHYDRATION IN A CHILD WITH DIARRHOEA
Age below 12 months Discontinuation of breast feeding Frequent stools (>8/day) Vomiting (>2/day) Severe malnutrition

33 ASSESSMENT OF DEHYDRATION
Clinical Signs Degree of Dehydration Mild Moderate Severe Gen. Condition * Eyes Tears Ant. Fontanelle Mucous membrane* Thirst * Well, Alert Normal Present Moist /coated Drinks eagerly Restless, Irritable Sunken Reduced/Absent Depressed Dry Thirsty, drinks eagerly Lethargic, Drowsy or unconscious Very sunken Absent Markedly depreesed Parched Drinks poorly or unable to drink

34 CLINICAL SIGNS OF DEHYDRATION Table cont’d
Degree of Dehydration Mild Moderate Severe Skin turgor Extremeties (capillary refill)* Goes back quickly Perfused Goes back slowly (<2s) Delayed (2-4s) Goes back v. slowly (>2s) Delayed ++ (>4s) +cold limbs

35 CLINICAL SIGNS OF DEHYDRATION Table cont’d
CLINICAL SIGNS OF DEHYDRATION Table cont’d * Best indicators of hydration Clinical Signs Degree of Dehydration Mild Moderate Severe Pulse (V / R) BP Respiration Urine output Normal Rapid Normal but orthostasis sed sed Rapid & feeble or impalpable sed & hyperpnoea sed/Absent Deficit or % body wt loss 5% or 3% 5-10%(mild) 3-6% (mod) 10 -15% or 6-9%

36 PREVENTION OF DEHYDRATION
Advise unrestricted oral fluids Continue breast feeding In high risk cases-advice unrestricted normal drinks and 10ml/kg of ORS after each watery stool passed. Conventional WHO ORS/ Low osmolarity ORS (Resomal) Teach mother how to prepare SSS at home/ Home made ORS ≈ WHO ORS

37 CORRECTION OF DEHYDRATION
Note: Rehydration can be achieved either by oral or intravenous route Oral rehydration therapy (ORT) is used for most cases Rehydration (correction of deficit) is achieved in 4 hours.

38 Fluid Amount Required Mild Dehydration 30 – 50ml/kg of ORS over 4hrs
Moderate Dehydration 60 -90ml/kg of ORS over 4hrs *Re-assess after 4 hrs, if dehydration persists, repeat above.

39 ORT is inappropriate for
Initial treatment of severe dehydration with signs of shock Patients with paralytic ileus or marked abdominal distention Patients unable to drink (However ORS solution can be given to such patients through N/G tube if IV is not possible).

40 Intravenous Therapy (IVT)
Mainly used for initial treatment of severe (life threatening) dehydration, to rapidly restore blood volume and correct shock. In severe dehydration with shock * Give 20-30ml/kg IV boluses of Ringer’s lactate or normal saline until organ perfusion is restored. Then continue rehydration with ORT

41 Intravenous Therapy (IVT) cont’d
* In case child is not able to drink, continue rehydration with IVT using 0.45% saline in 5% dextrose (or 0.18% saline in 4.3% dextrose based on serum sodium values). Calculate deficit and maintenance Give ½ deficit and 1/3 maintenance in 8hrs and the remaining deficit and maintenance in 16 hrs Add KCL (10-20mmol/500ml bag) soon as urine is passed. Reassess frequently

42 Treatment Isonatraemic Dehyration - treat as per standard protocol
Hyponatraemic Dehydration * Treat if serum Na <120mq/L. Calculate deficit thus (135-serum Na) x 0.6 x wt in kg. * Correct deficit over 24 to 48 hours.

43 Hypernatraemic Dehydration
* Degree of dehydration in hypernatraemic patients is usually underestimated because the hypertonic serum tends to keep the extra cellular fluid space intact. Thus cardiovascular instability does not develop until patient has lost large amounts of fluid. * 1st resuscitate patient if in shock using 20ml/kg normal saline (or ringer’s lactate).

44 Hypernatraemic Dehydration contd
* Next, aim at correcting the deficit (plus maintenance) slowly over 48-72hrs. * ORT (Resomal), is safer than IV Fluids in lowering serum Na level. Thus, if child can drink, use “Slow ORT”. - Rate of lowering serum Na level should be <10mmol Na/ lit /day (or 0.5mmol/lit/hr)

45 Hypernatraemic Dehydration cont’d
* If IV Fluid is used, 0.45% sodium chloride with 5% dextrose is preferred if serum Na > 160mmol/L. If child develops convulsion during rehydration, give anticonvulsants. 20% mannitol may also be used.

46 METABOLIC ACIDOSIS Normal PH = 7.35 – 7.45
If arterial pH < 7.2, or base deficit > -10, or child is clinically acidotic, then correct deficit. Rx = Correct Dehydration – this will correct the acidosis in most cases. : base deficit x 0.6 x wt (kg), give half of calculated value (diluted) in one hour and the remaining half over the next 8-12 hours. (1 ml NaHCO3 = 1mmol)

47 Metabolic alkalosis Base excess x 0.2 x wt (1 ml 20% NH4CL = 4mmol) Anion gap = Na – (CL + HCO3) = 8-12 ± 2 Unmeaured anions ses anion gap causes of ses anion gap (M U D P I L E S) Hyper Ca & hyper Mg reduces anion gap

48 Conclusion Gibbs Donan Equilibrium must be maintained
-Osmolality of ICF= ECF Osmotic force Potential difference (hypothetically)

49 Thank you

50 References Walmsley RN, Guerin MD. Disorder of fluid and electrolyte imbalance. Bristol: John Wright, 1984. Penny MD, Walters G. Are osmolality measurements clinically useful? Ann Clin Biochem 1987;24: Flenly DC. Arterial blood gas tensions and PH. Br J Clin Pharmacol 1980;9: Snyder J: The continuing evolution of oral therapy for diarrhea. Semin Pediatr Infect Dis 1994;5: American Academy of Pediatrics, Subcommittee on Acute Gastroenteritis: Practice parameter: The management of acute gastroenteritis in young children. Pediatrics 1996;97:


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