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
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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: