Report

Body Fluids • Total Body Water = Extracellular Fluid (ECF) + Intracellular Fluid (ICF) • ECF = Plasma + Interstitial Fluid • Total Body Water expressed in terms of % body weight (adolescent or adult): • ICF (30-40%) • Interstitial)15%( • Plasma 5% & Infants- 8% Change in Body Composition Change in Body Composition dehydration • Child: Mild- 5% weight loss Moderate 10 15-severe or shock • 3%/6%/9% old child & adults dehydration • Mild: thirsty, minimal clinical picture • Moderate: tachycardia, sunken eyes, dry mucous membranes, depressed fontanel, decreased urination (???- only 20% of "oliguric" patients have dehydration!), ± prolonged capillary refill • Severe: blood pressure drop dehydration • Isotonic dehydration • hypertonic (Na≥150) • hypotonic (Na≤130) dehydration • Acute< 3 days 75-100% of fluids losses is from ECF (primarily Na loss, less K loss) • Subacute or chronic> 3 days 65-70% of losses from ECF and 30% from ICF with greater level of potassium loss Treatment of dehydration • Fluids!!!!! • Etiologic treatment Treatment of dehydration • Rout of fluids administration: enteral and parenteral Treatment of dehydration • Oral/PZ- preferable & most physiologic type – Hypotonic type: ORS by 40-60meq Na/20 meq K and 2.5D for non choleric patients – Medium type: 70meq Na – High solute type: 60-90Na for cholera 1 cc/kg for mild and 2cc/kg for moderate dehydration for 4 h every 5 minutes Dehydration treatment Oral rehydration contraindications: • intractable vomiting • impaired consciousness • aspirations risk • bowel obstruction Treatment of dehydration • Parenteral: – Subcutaneous with recombinant hyaluronidase adjuvant – IV/io for failed ORS or Moderate-Severe dehydration IV dehydration correction • 3 phases – Emergent – Corrections – Maintenance and ongoing losses Emergent phase of fluid replacement perfusion failure and intravascular deficit by bolus of correction of isotonic fluids 0.9 NaCl±D5 or Ringer lactate 20ml/kg (previous mass!) • Bolus- within minutes! • Repeat boluses until stable Emergent phase • Patient with decreased oncotic pressure (nephrotic syndrome, protein-loosing entheropathy, burns, cirrhosis)- may give 5% albumin • DKA- start 10 ml/kg • Premature and small newborns- 10 ml/kg • Suspected cardiogenic shock – 10ml/kg Second phase- deficits correction Deficits: H O+ Na+ K± Ca 2 Deficits correction • Assess degree of dehydration • Assess type of dehydration • Assess length of dehydration Deficits correction • FIRST - calculate the amount of fluid you need • NEXT - calculate how much sodium and potassium you need • FINALLY - pick a fluid based upon what is commercially available if you can Deficits correction Persistent deficits= previous loss- boluses Most accurate method of water deficit estimation- weight loss Other method: Calculated previous weightcurrent weight Calculated weight= current+ estimated fluid loss Estimated fluid loss- by percent of dehydration Isotonic dehydration • Water deficit- weight loss or estimated weight loss • Sodium deficit Isotonic dehydration sodium deficit total body water(normal)*140meq/l- current TBW*current [Na]= Na deficit Isotonic dehydration • Normal TBW= normal body mass*K k~0.75 neonates, 0.65 toddlers, 0.6w &0.5m • ??????Really Current TBW~ current mass (kestimated percent of dehydration/10) 10 kg infant with 10% dehydration- 1l loss Sodium deficit= 1*140 meq/ml Sodium maintenance= 3meq/100 ml of water*daily fluids Isotonic dehydration • Replacement and maintenance by isotonic or ½ NS based fluids • Give 100-70% of deficit at 1st day • Give 1st half of day fluids amount at 1st 8h and rest at 16h • New recommendations- to give NS based fluids to prevent iatrogenic hyponatremia Ongoing Repletion and Maintenance Therapy • Once the patient is stable Persistent deficits+ ongoing losses+ maintenance fluids Fluid maintenance: Holliday Segar formula • 1st 10kg- 100 ml/kg • 2nd 10kg- 50ml/kg • Others- 20ml/kg • ~400 ml/m²/d+ renal sensible loss Caloric (energy) maintenance • The daily fluid requirement is the same as the daily caloric requirement (e.g., if a child requires 1000 cc fluid, he also requires 1000 Kcalorie • In terms of fluids, calories most often provided as dextrose (glucose) • Difficult to provide total daily caloric requirement intravenously unless using TPN • Most often, it is sufficient to provide 20% of total daily caloric requirement intravenously so as to prevent ketosis Ongoing loses • • • • Sensible: diuresis and diarrhea (rectal tube) Insensible: feces, skin, respiration 10ml/kg for each diarrhea Burns- Parkland formula: BSA*4*mass for >20% of TBS of 2nd degree and > • Tachypnea: 5-10ml/kg/10resp> normal • Hyperthermia: 5-10 ml/kg/1°>38 • Vomiting:5-10 ml/kg/event Decreased maintenance • SIADH • Ventilated children • Inactive/hypothermic children Example of isotonic dehydration • 1y boy with moderate dehydration • Water and sodium (Na) deficits simple calculation: loss of 1 l of isotonic fluids Water deficit: 10 kg × 10% = 1 L Na deficit: 1 L × 140 mEq/L = 140 mEq • Emergent fluid repletion with NS or D5% NS 20 mL/kg × 10 kg = 200 mL (200 mL water and ≈30 mEq sodium) Ongoing repletion and maintenance requirements Remaining water deficit: 1,000 mL - 200 mL = 800 mL Daily maintenance water requirement: 100 mL/kg/day × 10 kg = 1,000 mL/day 800 mL + 1,000 mL = 1,800 mL/24 h = 75 mL/h Remaining Na deficit: 140 mEq - 30 mEq = 110 mEq Maintenance sodium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day 110 mEq + 30 mEq = 140 mEq/24 h 140 mEq/1,800 mL ≈ 0.45% sodium chloride (½ NS) Maintenance potassium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day 30 mEq/1,800 mL ≈15–20 mEq/L Intravenous fluid based upon deficit calculations: D5% 1/2 NS with 20 mEq/L KCl at 75 mL/h Ongoing losses Extrarenal losses should be replaced mL-for-mL if volumes are significant. The sodium content of the fluid lost should be estimated or measured in order to select the appropriate replacement fluid. Hyponatremic (125) dehydration example Water and sodium deficits Water deficit: 10 kg × 10% = 1 L Sodium deficit: [TBW(n) × 140 mEq/L] - [TBW(c) × 125 mEq/L] TBW(n) = 10 kg × 0.65 = 6.5 L TBW(c) = TBW(n) - water deficit = 6.5 L - 1 L = 5.5 L Sodium deficit: (6.5 L × 140 mEq/L) - (5.5 L × 125 mEq/L) ≈ 220 mEq Emergent fluid repletion with NS or D5%NS 20 mL/kg × 10 kg = 200 mL (200 mL water and ≈30 mEq sodium) Ongoing repletion and maintenance requirements Remaining water deficit: 1,000 mL - 200 mL = 800 mL Daily maintenance water requirement: 100 mL/kg/day × 10 kg = 1,000 mL/day 800 mL + 1,000 mL = 1,800 mL/24 h = 75 mL/h Remaining Na deficit: 220 mEq - 30 mEq = 190 mEq Maintenance Na requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day 190 mEq + 30 mEq = 220 mEq 220 mEq/1,800 mL ≈120 mEq/L Maintenance potassium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day 30 mEq/1,800 mL ≈15–20 mEq/L KCl Intravenous fluid based upon deficit calculations: D5% with 120 mEq/L Nacl and 20 mEq/L KCl at 75 mL/h D5%NS with added potassium could be provided for the initial half of the total volume and completed with D5%1/2 NS with added potassium Hypernatremic dehydration example Total Fluids loss= free water losses+ isotonic fluids losses FreeH2O deficit = TBW(c) × [(serum Na/140) - 1] Total fluid deficit- free water deficit= isotonic losses • Water and sodium deficits Total water deficit: 10 kg × 10% = 1 L TBW(c) = TBW(n) - 1L = (10 kg × 65%) - 1 L = 5.5L Free water deficit: TBW(c)[(155/140) - 1] = 5.5[(155/140) - 1] = 0.59 L Isotonic deficit = total water deficit - free water deficit = 0.41 L Sodium deficit: 0.41 L × 140 mEq/L ≈ 60 mEq • Emergent fluid repletion with NS or D5%NS 20 mL/kg × 10 kg = 200 mL (200 mL water and ~30 mEq sodium) Ongoing repletion and maintenance requirements Remaining total water deficit: 1,000 mL - 200 mL = 800 mL, plan to replace over 36–48 h or 400 mL/day × 2 days Daily maintenance water requirement: 100 mL/kg/day × 10 kg = 1,000 mL/day 1,000 mL + 400 mL = 1,400/24 h or ≈60 mL/h Remaining sodium deficit: 60 mEq - 30 mEq = 30 mEq Maintenance sodium requirement: 3 mEq/100 mL of water intake × 1,000 mL/day = 30 mEq/day Total sodium requirement: 30 mEq + 30 mEq = 60 mEq 60 mEq/1,400 mL or ≈0.225% sodium chloride • Maintenance potassium requirement: 3 mEq/100 mL water × 1,000 mL/day = 30 mEq/day 30 mEq/1,400 mL ≈20 mEq/L KCl D5% 1/4 NS with 20 mEq/L KCl at 60 mL/h for ~36–48 h • • • • Correct sodium 10-12 mEq/l per 24 h Acute states- rate may be higher Chronic state- decrease the rate of correction Estimate the rate of correction by planning of free water deficit replacement Sodium • Predominant solute of extracellular space • Concentration inversely related to total body water • Osmotic gradient • Membrane potential • Normal measured concentration: 135-145 • Measured Na+ (0.016*serum glucose (mg/dL)= Corrected serum Na • Other pseudohyponatremias- hyperlipidemia & paraproteinemia sodium • Normal intake: 2-3 meq/kg/d Signs of hypernatremia • 145- 150-158- mild/moderate signs – Intense thirst – restlessness Severe hypernatremia • 158–160 mmol/l • severe signs due to rupture of brain vessels especially in rapid developed hypernatremia due to brain volume fall with subsequent brain separation from meninx Severe hypernatremia – Absent thirst – altered mental status – anorexia – muscle weakness – nausea – vomiting – lethargy – irritability – Stupor or coma – vascular rupture with cerebral bleeding and subarachnoid hemorrhages • Chronic hyperNa- minimal neurological symptoms due to neuronal adaptation by osmolytes (amino acids and carbohydrates) production within 72 h- don’t repair rapidly to prevent brain edema correction • 1st step- correct intravascular volume depletion by bolus • A & B stabilisation • For acute hypernatremia- acute correction 1 mmol/h • For hypernatremia of longer or unknown duration- slow correction 0.5 mmol/h till145 • • • • • • • • Anorexia Headache Nausea Vomiting Irritability Disorientation Weakness & cramps- rhabdomyolisis Seizures and coma due to cerebral edema in case of rapidly progressive hyponatremia • Death 1st tx step- volume replacement by isotonic fluids especially in hemodinamically unstable patient + A& B stabilization including intubation and seizures control • Correction: 8–12 mmol/l/d for chronic hyponatremia to prevent demyelination • Mechanism of demyelination: rapid osmolarity repair→ fluid efflux from brain blood barrier endothelium→ endotheliocytes constriction→ opening pores in BBB→ plasma inflammatory substances (TNF & interferon) attack of glya • Acute tx for acute severe hyponatremia (symptomatic): start after hemodynamic stabilization 4-6 ml/kg NaCl3% bolus • Water restriction and loop diuretics+ salt supplements in neurologically intact or hypervolaemic patient without fluid resuscitation • Water restriction in euvolaemia Signs Muscular: • Usually ascending • doesn’t involve respiratory muscles- DD with hypo K • appears then K>8 • Fatigue • Weakness • Paresthesia • muscular paralysis/tetany Cardiac: • Peaked T- earliest ECG sign • 2nd- flat P • prolonged PR/QRS, BBB, VF, asystole • The rapider K rises the severer clinical picture • Hyponatremia, acidosis, hypoCa- more rapid and sever clinical picture • Pseudo hyperkalemia: serum K- plasma K> 0.3 mmol treatment • • • • • • Ca to prevent arrhythmia Insulin +D Bicarbonate Ventoline Key oxalate diuretics signs • Mild 3.0-3.5 mmol/l- arrhythmia in cardiac patients Moderate 3- 2.5: • ascending muscle weakness & diaphragmatic paralysis • hypertension • paralytic ileus • flat or inverted T; ST depression • prominent U-waves • atrial tachycardia± block • atrioventricular dissociation • VT/F/SVT especially on digitalis Severe< 2.5: • Myopathy • Rhabdomyolysis • ascending paralysis • respiratory failure • myocardial necrosis • constipation • urinary retention and voiding dysfunction