FLUID AND ELECTROLYTES of the human body.pptx

Fluid and electrolytes. Fluid resuscitation.

1. FLUID AND ELECTROLYTES

2. GENERAL CONSIDERATION TOTAL BODY WATER (TBW): Most of the body is water. The total body water (TBW) varies with age: Fetus has a very high TBW (90% water) Preterm babies have higher TBW (80% water) At birth, the TBW in term newborn is about (70-75%) of body Wt. Young children: 65-70% water Adolescents: 60% water

3. II. FLUID COMPARTMENTS: The TBW is distributed in various locations throughout the body, known as fluid compartments The main two compartments are : Extra Cellular Fluids (ECF) Intra Cellular Fluids (ICF)

4. Extra Cellular Fluids (ECF) In fetus the ECF volume is larger than the ICF volume and the ECF decreases with age. The ECF volume drops after birth (due to postnatal dieresis). The ECF volume in the children is 1\3 of TBW, 20 – 25 % of body weight. The ECF compartment is further divided: Interstitial fluid : 3\4 of ECF, 15% of body weight. Plasma water : 1\4 of ECF, 5% of body weight.

5. Intra Cellular Fluids (ICF) Constitutes 2\3 of TBW, 30 – 40 % of the body weight. Other compartment Trans cellular Fluids: 1 – 3 % of body weight in (CSF, Synovial fluid, digestive Juices, Pleural and peritoneal fluids). Slowly exchangeable fluid compartment: 10% of the body weight in (bone, connective tissue and cartilage).

6. Body fluid compartment or DYNAMIC, there is ongoing equilibrium between the intracellular and extracellular spaces – diffusional gradients, Osmotic forces and activity of cellular pumps or transporters combine to establish differences in the composition of body compartments.

7. Osmosis Movement of water across a semi-permeable membrane from an area of low solute concentration (lots of water) to an area of high solute concentration (less water) until even distribution (homeostasis) is achieved Osmolarity = number of milli-osmoles in liter of solution Normal = 270 – 300 (or 275 – 295) Osmolality = number of mill- osmoles in kilogram of solution

8. Isotonic Fluids example: normal saline 0.9% NaCl No net fluid (water) shifts occur because the fluids are EQUALLY concentrated

9. Hypotonic Fluids example: 0.45% NaCl When a LESS concentrated fluid is placed next to a MORE concentrated solution, water moves to MORE concentrated solution to equalize the solutions

10. Hypertonic Fluids example: 3% NaCl When a MORE concentrated fluid is placed next to a LESS concentrated solution, water moves to the MORE concentrated solution to equalize the solutions

11. Regulation of Body Fluids and Electrolytes Mechanism to Regulate ECF volume Anti-Diuretic Hormone (ADH) Kidney = Increase water reabsorption ADH secretion is regulated by tonicity of body fluids Thirst Not physiological stimulated until plasma osmolality is >290

12. Anti-Diuretic Hormone (think beer)

13. Regulation of Body Fluids and Electrolytes Aldosterone Released from the adrenal cortex Decrease circulating volume Stimulation by Renin-Angiotensin Aldosterone axis Increase plasma K Enhanced renal reabsorption of Na in exchange for K (>Na = expansion of ECF) Atrial Natriuretic Factor Secreated by the cardiac atrium in response to atrial dilatation (regulates blood volume) Inhibits Renin secretion Increase GFR and Na excretion

14. Normal water and electrolytes requirements Fluid and electrolytes required to replace daily losses and to maintain an overall net balance of zero gained or lost are often referred to as “maintenance” needs. These needs vary from day to day and from individual to individual.

15. Daily water requirments : Historically, daily water needs have been estimated based on energy expenditure: 1 kcal expended/day = 1 ml H2O required Based on computed energy expenditure of the average hospitalized patient: First 10 kg = 100ml/kg/day H2O Second 10 kg = 50 ml/kg/day H2O Weight over 20 kg = 20 ml/kg/day H2O Therefore, for a 25kg child, the daily fluid requirement based on this scheme would be: 1000ml/day for the first 10kg (10kg X 100ml/kg/day) 500ml/day for the second 10kg (10kg X 50ml/kg/day) + 100ml/day for the 5kg over 20kg (5kg X 20ml/kg/day) TOTAL:1600ml/day for 25kg child

16. The maintenance water requirement is determined by the quantity of water loss. The daily obligatory water loss occurs by three routes: Fluid and Electrolyte Therapy: The goal of maintenance therapy is the accurate replacement of ongoing water and electrolyte losses to maintain zero balance; that is: INTAKE = OUTPUT. In very unstable patients with abnormal or unpredictable losses, zero balance can be achieved only by frequent replacement of precisely measured losses. In more stable patients, it is clinically useful to begin fluid therapy by estimating normal maintenance requirements using the estimated caloric expenditure method.

17. Abnormal Maintenance Increased Maintenance fluid requirement: –Fever (12.5% per degree > 38C) Increased sweating Hyperpnea Vomiting Diarrhea High environmental temperature Hyperosmolar states (dehydration, DKA) Hyperventilation (asthma, RSV) Decreased maintenance fluid requirements: –Decreased renal function Increased environmental humidity Hypothermia Hypometabolic states

18. 2- daily electrolyte requirements: Estimates for daily electrolytes can be based on metabolic demands or, by extension, on daily water needs : • Sodium 2 - 3 mEq/100ml H2O /day • Potassium 1 - 2 mEq/100ml H2O /day • Chloride 2 - 3 mEq/100ml H2O /day

19. Although there are unusual clinical situations with large electrolyte losses from the skin or GI tract, most patients lose their daily electrolytes in urine . Consequently , oligouric patients require significantly less electrolyte replacement to maintain balance. By contrast , patients with renal tubular dysfunction, who lose excess electrolytes in large volumes of urine, may require very high levels of electrolyte supplementation. Patients with unusual losses will require careful monitoring and adjustment to their electrolyte replacement regimen.

20. Dehydration Factors producing dehydration : Dehydration or contraction of the body fluid compartments will occur whenever the loss of water and salt exceeds the intake. Fever, sweating and diarrhea produce losses in excess of normal, but if intake remains good, patients will often be able to compensate for the increased losses. Anorexia and/or vomiting will impair this ability to compensate; in fact, due to continuing obligatory losses, dehydration can occur even in the absence of abnormal losses if anorexia is severe or prolonged.

21. Pathophysiology Pediatric dehydration is frequently the result of  gastroenteritis , characterized by vomiting and  diarrhea . However , other causes of dehydration may include poor oral intake due to diseases such as stomatitis, insensible losses due to fever, or osmotic diuresis from uncontrolled diabetes mellitus. Volume depletion denotes lessening of the total intravascular plasma, whereas dehydration denotes loss of plasma-free water disproportionate to the loss of sodium. The distinction is important because volume depletion can exist with or without dehydration, and dehydration can exist with or without volume depletion

22. Causes In most cases, volume depletion in children is from fluid losses from vomiting or diarrhea. Vomiting may be caused by any of the following systems or processes: CNS ( eg , infections , space-occupying lesions ) GI ( eg , gastroenteritis, obstruction, hepatitis, liver failure, appendicitis , peritonitis,  intussusception , volvulus , pyloric stenosis , toxicity [ingestion, overdose, drug effects]) Endocrine ( eg ,  diabetic ketoacidosis [DKA],  congenital adrenal hypoplasia , Addisonian crisis) Renal ( eg , infection ,  pyelonephritis, renal failure , renal tubular acidosis) Psychiatric ( eg , psychogenic vomiting) - This is not seen in infants and is rare in children compared with adults.

23. classification It is classified on the basis of severity and types of dehydration: 1 . SEVERITY : Dehydration is classified into mild, moderate and severe according to the clinical manifestation, as it is shown in the following table :

24. SEVERE (>9% BODY WEIGHT LOST) MODERATE (3-9% BODY WEIGHT LOST) MILD (<3% BODY WEIGHT LOST) SYMPTOM Apathetic , lethargic , unconscious Restless or fatigued , irritable Normal, alert Mental status Tachycardia or bradycardia Normal to increased Normal Heart rate Weak , thready , impalpable Normal to decreased Normal Quality of pulse Tachypnea and hyperpnea Normal to increased Normal Breathing Deeply sunken Slightly sunken Normal Eyes Deeply sunken Slightly sunken Normal Fontanelles Absent Normal to decreased Normal Tears

25. 2- Types of Dehydration: The type of dehydration is a reflection of the relative net lossses of water and electrolytes and is based on serum sodium concentration : I. Isotonic ( Isonatraemic) : Accounts for about 70% of cases. - Proportionate of water and soduim . - Serum Na 130 – 150 meq \I. II. Hypertonic ( Hypernatraemic ): - 20% of cases. - Disproportionate large net losses of water compared with losses of sodium. Serum Na > 150 meq \I III. Hypotonic ( Hyponatracmic ): 10% of cases Losses of large amount of sodium out of proportion to water losses. Serum Na < 130 meq \I

26. Different types of dehydration may have different clinical manifestation. Physical signs in moderate – severe dehydration of the three types : Hyponatraemic Hypernatraemic Isonatraemic Signs 10% 20% 70% Rate of occurrence 1 Very poor fair poor Turgor 2 Clammy Thick, Doughy Dry Feel 3 Dry Parched Dry M. Member 4 Sunken Sunken – tense – bulging Sunken Ant. Fontanel 5 Very lethargic Hyper-irritable Lethargic Consciousness 6 Rapid Moderately rapid Rapid Pulse 7 Very Low Moderately Low Low BP 8 * Patients with Hyponatraemic dehydration because of external losses and internal fluid shifts may present with signs of profound volume depletion and shock.

27. Fluid therapy: Categories fluid therapy consist of three categories: 1- Maintenance therapy (M): It replaces the usual body losses of fluid and electrolytes. 2- Deficit therapy (D): Deficit is described as losses per kg of body weight. Deficit therapy replaces the abnormal losses of fluid and electrolytes. Usually as a result of an illness.

28. It is determined by : Decrease of body wt (difference between two weight within 24 hr ). Clinical criteria. Patients with deficits result from different causes can be treated successfully in a similar manner. Management of deficit depends on: Severity (degree) of dehydration. Type of dehydration (based on relative water and Na loss) Severity (degree) of dehydration: Mild : loss of body wt < 5%. Moderate : loss of body wt 6-9 % Severe : loss of body wt > 10%

29. 3- supplemental replacement of ongoing loss : Is based on measured or estimated continuing abnormal losses (excessive loss in diarrhea, vomiting, gastric aspiration, surgical aspiration… etc )

30. Types of fluid therapy

31. 1- oral rehydration therapy : by oral rehydration salts (ort) It is usually used for mild and moderate dehydration. ORT is divided into two stages: 1- Deficit replacement: - quantity : Mild dehydration 50 ml.kg over 4 hours. Moderate dehydration 100 ml.kg over 4-6 hours If diarrhea persists give supplementary ORS for this ongoing loss: 10 ml.kg for each bowel motion. If vomiting persists or occurs give ORS very slowly in small Amount and short interval: 1 TSF each 1-2 minutes for the first 2hr, then increase gradually.

32. After rehydration give breast feeding or formula, because early feeding reduces the duration of diarrhea. ORS should preferably be given with a teaspoon or in small sips from a cup. Large gulps of fluid stimulated gastrocolonic reflex resulting in a quick passage of stool and often vomiting.

33. 2- Maintenance ORT: After hydration has been achieved; ORS with a lower concentration of Na will suffice for maintenance needs of fluid and electrolytes. - Quantity: 100 ml.kg 24 hr. - solution for maintenance: - Half strength of the UNICEF or WHO “ORS”. - solution that contains 50 meq \I, such as pedialyte - Alternative use of breast milk or plain water with the UNICEF ORS.

34. C omposition of UNICEF WHO “ORS” and pedialyte solution: Pedialyte WHO “ORS” Contents 45 90 Na ( Meq \I) 20 20 K ( Meq \I) 30 30 Base ( Meq \I) 140 111 Glucose ( mmol \I) 250 310 Osmolality ( m.osm \Kg)

35. “ORS” (WHO) is composed of : Na cl Na CHO K Cl Glucose Ur Sugar This is diuted in one liter of H2O and Will give : Na 90 meq \I Cl 80 meq \I HCO3 30 meq \I K 20 meq \I Calories 80 Glucose is the preferred sugar for use in ORT. Because it facilitates the absorption of Na + H2O in the GIT

36. Parenteral (iv) therapy: Indications : 1- severe dehydration. 2- shock ( hypovolemic shock) 3- Uncontrollable vomiting. 4- patients who are unable to drink (extreme vomiting, stupor or coma) 5- Patients with gastrointestinal distension. 6- Diarrhea with quantity of > 10ml\kg\ 1 hour. It has two phases : Initial therapy and subsequent therapy. 1- Initial therapy. 2- Subsequent therapy.

37. Initial therapy Its goal is to extent the ECF volume rapidly and to improve the circulation and renal function. Indication: severe dehydration of all types ( Iso , Hypo, Hypernatreamic ). Type of solutions used in this phase: Isotonic solution, similar to plasma in composition should be used: isotonic saline< NS (0.9 % Nacl ), Ringer lactate. Quantity: 20 ml – 40 ml \ kg \ hour (rapid bolus) could be repeated. Initial therapy is completed when the child has an adequate intravascular volume or general clinical improvement such as : Lower heart rate. Normalization of BP. Improve perfusion . More alert condition . Blood, 5% albumin and plasma may occasionally be used for initial fluid therapy (boluses): For a patient with severe coexisting anemia, and if electrolyte solution are unavailable. Never use hypotonic solution, because it may lead to sudden drop of serum Na which may cause convulsion.

38. Subsequent therapy It consists of : Remaining deficit or deficit which is estimated according to the degree of dehydration: Mild 50 ml\kg - Moderate 80 ml\kg - Severe 100 ml\kg Maintenance: depends on energy expenditure as discussed previously. Ongoing loss: should be calculated. Types of fluid in subsequent therapy : depend upon the type of dehydration: Isonatraemic . Hyponatraemic . Hypernatraemic .

39. Isonatraemic : Hyponatraemic : Hypernatraemic : The fluid should contain 10 meq \I Na and 40 meq \I K Each 6.5 ml of NS contains 1 meq Na. Duration of deficit replacement depends on the type of dehydration: Isonatraemic : 24 hr. Hyponatraemic : 36 hr . Hypernatraemic : 48 hr or more Sodium concentration Body weight 50 meq\I ≈ ⅓ Ns 3 – 20 kg 60 meq \I ≈ Ns 21 – 50 Kg 154 meq \I 1 NS > 50 kg Sodium concentration Body weight 50 meq\I ≈ ⅓ Ns 3 – 20 kg 21 – 50 Kg 154 meq \I 1 NS > 50 kg Sodium concentration Body weight 77 meq \I ≈ Ns 3 – 10 kg 116 meq \I ≈ 3\4 Ns 11 – 20 Kg 154 meq \I 1 NS > 20 kg Sodium concentration Body weight 3 – 10 kg 116 meq \I ≈ 3\4 Ns 11 – 20 Kg 154 meq \I 1 NS > 20 kg

40. Types of Dehydration Isonatremic - cells neutral Hypernatremic - cells shrunken and can have rebound Hyponatremic - cells swollen

41. Types Isonatremic 80 % of all dehydration Proportional loss of salt and water Treatment : Calculate deficit from decreased weight Replace intravascular volume with isotonic solution such as lactated ringer’s Calculate maintenance From tables calculate estimate of water, sodium and potassium deficit

42. Orders Standard sotonic rehydration 10-20 cc/ kgm (more important to restore vascular volume) Calculate deficit Give ½ over 8 hours Give ½ over 16 hours Calculate maintenance Run piggyback Calculate ongoing losses Replace hourly

43. Orders In Reality Emergency Room - isotonic rehydration 10-20 cc/kg or until looks better Home on oral rehydration solution 5cc/minute = 300 cc/hour Key is to restore intravascular volume

44. Oral Rehydration Therapy Preferred for mild/moderate dehydration Recommended by the AAP, WHO, CDC Advantages of ORT: Less expensive/fewer complications than IV therapy Applicable in any patient care setting Contraindications to ORT: Severe dehydration, intractable vomiting shock, impending shock Lack of personnel to administer ORT

45. ORT Failure Indications of ORT failure Clinical deterioration Failure to rehydrate in 8 hours Intractable vomiting/high purging rate Institute IV therapy Use of IV therapy does not preclude resumption of ORT after rehydrated

46. Appropriate Fluids CHO/mmol/L Na K Base Osmo WHO formula 140 45 20 48 265 Pedialyte 140 45 20 30 250 Not appropriate: Cola 700 2 0 13 750 Apple juice 690 3 32 730 Chicken broth 0 250 8 500

47. Hyponatremia USUALLY means Serum osmolality is below normal except for Hyperlipidemia Hyperglycemia/ mannitol - which adds osmoles

48. Hyponatremic dehydration 5% of all dehydration Usually occurs with a child who has high GI losses accompanied by water replacement ( Jello /pop, etc.) Water shifts into the intracellular space to balance osmoles , so child looks sicker since ECF is compromised Causes significant neurological problems as brain swells Seizures If Na <120 meq /L - can cause permanent myelinolysis

49. If Na is above 120 meq /L Replace intravascular volume with isotonic solution Calculate Na deficit desired Na - measured Na X TBW (TBW = 0.6 X body wt.) Use D5 1/2 NaC1 = 75 meq /liter of Na to replace deficit Do not change serum more than 0.5-1 meq /L/ hr Add in maintenance +/- potassium

50. Hyponatremia : Correction Ex : Na 120, in 15 kg child want to correct to 135 Calculate Na deficit ( 135-120) x .6 (15) = 135 meq D5W.45 = 75meq/L =1.8L Correct total 15 meq over 24 hrs Run at 75cc/ hr + maintenance Check Na q2-4 Hr and MAKE ADJUSTMENTS

51. If Na<120 meq /L, assess hydration very carefully If dry, give 20 cc/ kgm of Isotonic solution You may use hypertonic saline if CNS signs are evident = 3% NaCl 514 meq /liter = 1028 mosm /L or 0.5 meq NaCL per cc Risk of seizures

52. Calculate deficit of sodium to get you to 120 In a 10 kg child with a sodium of 110 ( CD-CA) X 0.6 wt /kg ( 120-110) X .6 X 10 10 X .6 X 10 = 60 meq 60 meq NaC1 = 120 cc of 3% NaCl Give over 1-2 hours rechecking Na+ every 30 minutes

53. Hypernatremia (Na > 150 meq /L) ALWAYS means Serum osmolality is above normal

54. Hypernatremic dehydration 15 % of all dehydration Seen in children with deprivation of water Breast-feeding failure Children with losses replaced by high sodium foods ( broth, etc.) Water moves out of the intracellular space and the ICF is compromised Na + > 160 meq /L causes CNS effects With shrinking of the brain there can be tearing of bridging blood vessels causing subarachnoid or subdural bleeds .

55. Treatment -- SLOW!!! If child is stable and hypernatremic and got that way over weeks, you may take a week to correct If child is in shock, give isotonic solution 10-20 cc/kg to get out of shock Calculate water deficit 4 cc/kg for every meq that serum Na exceeds 145 i.e . Na 160 in 10 kg child 4X 10 X 15 = 650 cc water or 1300 cc of 1/2 NaCl Correct no faster than 0.5-1 meq / hr Run as 1/2 NaCl over 30 hrs = 1300 cc / 30= 43 cc/ hr

56. Deficit Replacement-Hypertonic Hypernatremic dehydration Clinically , the most difficult & dangerous to tx Treat shock w/ 0.9% NSS (20 mL/kg) IVB over 1/2-1 hr Then , D 5 0.45% NSS w/ 20-40 mEq / L KCL

57. Deficit Replacement-Hypertonic Duration of correction based on serum Na: Serum Na+ 150-170 mEq /L : correct over 48 hrs Serum Na+ > 170 mEq /L : correct over 72 hrs Serum Na+ > 200 mEq/L: dialysis

58. Deficit Replacement-Hypertonic Hypernatremic dehydration Complications : Cerebral swelling/brainstem herniation Hyperglycemia : unclear why, decrease dextrose to 2.5% Hypocalcemia : unclear why, supplement Ca Gluconate to IVF

59. Summary Cells need adequate circulating volume to survive: always assess and maintain adequate vascular volume which is part of the extracellular space Cells are at risk with rapid shifts in osmolality. Rapid fluid expansion should always occur with isotonic fluid