2Fluid Compartments Total body water(TBW)= ICF + ECF = 50-60% weight ICF = 2/3 TBWECF = 1/3 TBWInterstitial fluid = 2/3 ECFIntravascular fluid(blood volume) = 1/3 ECFEstimates of TBW should be adjusted down approximately 10 to 20% in obese individuals and up by 10% in malnourished individuals. The highest percentage of TBW is found in newborns, with approximately 80% of their total body weight comprised of water. This decreases to about 65% by 1 year of age and thereafter remains fairly constant.
3Composition of Fluid Compartments ICF = K, Mg, Phos, proteinsNa determines intracellular/extracellular osmotic pressureECF = plasma & interstitial fluid very similar. Plasma has a higher protein concentration.Na is confined to the ECF(1/3 plasma, 2/3 interstitial space) - IVF w/Na expands the interstitial space more than it does the intravascular space.
4Maintenance Fluid: Composition What is D5 NS + 20KCl?D5 = 5% glucose = 5g dextrose/100mL of solution or 50g/L (prevents mobilization of protein as fuel source)1L NS = 154mEq Na, 154mEq Cl20KCl = 20mEq KCl per LWhat is LR?1L LR = Na 130 mEq, K 4 mEq, Ca 3 mEq, Cl 109 mEq and lactate 28 mEq.The electrolyte content is isotonic (273 mOsmol/L) in relation to the ECF (approx. 280 mOsmol/L).The pH of the solution is 6.6.
5Maintenance IVF: Adults MIVF rate calculation: 4 / 2 / 1 rule (per hour)For the first 10kg → 4mL/kg/hrFor the next 10-20kg → 2mL/kg/hrFor each kg after 20kg → 1mL/kg/hrTypical MIVF: D5 1/2NS +20KClElectrolyte requirements:Sodium = 2-3 mEq/kg/dayPotassium = mEq/kg/day
6IVFs After SurgeryFluid Loss during surgery L/hour, + blood lossCalculate initial MIVF rate with rule, then adjust for blood lossUse LR/NS for first 24 hours, then switch to D5 2 NS +20KClDaily BMPs while NPO to manage electrolytes
7Resuscitation Remember your ABC’s C = includes IV access Important: what is adequate IV access?Evaluate hemodynamic status: look at BP, HR, skin perfusion, temperature, mental statusStart with isotonic crystalloid fluidsInitial bolus: 20mL/kg in children, 2L in adultsAssess response to bolus:If responsive, continue evaluationIf unresponsive, THERE IS A PROBLEM THAT YOU NEED TO IDENTIFY NOW: bleeding, cardiac tamponade, spinal cord injury, tension PTX, MI, myocardial contusion, air embolism
8Assessment of Volume Status Daily weightsSwelling/edemaEdema pattern on CXRUOPUOP > 0.5mL/kg/h adultsUOP for children > 1mL/kg/h
9Case #1: Presentation H&P: 6wk-old, first-born M p/w 5d h/o projectile nonbilious, postprandial emesis - otherwise, pt w/good appetitePE: firm, mobile “olive” in epigastrum, and visible gastric peristaltic wavesU/S: pyloric muscle elongated & thickened (4mm thick)Questions:What is the diagnosis?What is the associated metabolic/electrolyte abnormality?What is the management?Olive most easily palpated after vomiting - often felt in the RUQ
10Electrolyte Abnormalities GI (vomiting/diarrhea) – K and ClStomach – H and ClBile/Pancreas – bicarbHypochloremic, hypokalemic metabolic alkalosis
11Hyperkalemia Renal failure (missed dialysis), hemolysis Peaked T waves on EKGManagement – confirm lab value (r/o lab hemolysis)Calcium gluconate for heart (stabilizes membranes)NaBicarb, 10U insulin, 1 amp dextroseKayexalate / DialysisHyokalemia can cause an ileus
12Hyponatremia Hypernatremia – tx with free water SIADH, Rule out hyperglycemia (pseudohyponatremia)Water restriction, diuresis, replacmentSlow Na correction (1mEq/hr)Avoid central pontine myelinosisHypernatremia – tx with free water
13HypercalcemiaSeen in hyperthyroidism, parathyroid tumors, bone metastates, renal failureBones, stones, moans, psychiatric overtonesTx: NS + lasixAvoid LR (has Ca)Avoid thiazide diuretics (retains Ca)Calcitonin, dialysis
14Case #1: Resolution Dx: Hypertrophic pyloric stenosis (HPS) Metabolic abnormality: hypochloremic, hypokalemic metabolic alkalosis with paradoxical aciduriaLoss of H+ and Cl- with vomitingInitial excretion of Na-bicarbonate in response to Cl lossAldosterone acts to promote K excretion for Na retentionFinally, H exchanged for Na, resulting in paradoxic aciduriaTreatment:+/- NS bolus, when UOP is demonstrated, K is added to IVFD5 ½ NS x maintenanceMust resolve electrolyte abnormalities prior to surgeryPyloromyotomy: laparoscopic vs. openAdvance PO intake as tolerated
15Take Home Points 4-2-1 rule for calculation of MIVF rate ABC(DE) is important in many situationsBolus IVF are not the same as MIVFAction is required if a patient is unresponsive to initial resuscitation