Presentation on theme: "PEDIATRIC PERIOPERATIVE FLUID THERAPY"— Presentation transcript:
1 PEDIATRIC PERIOPERATIVE FLUID THERAPY Evangeline Ko-Villa, MD, DPBAClinical Associate ProfessorUP-PGH Department of Anesthesiology
2 ObjectivesReview relevant physiological considerations in the pediatric populationReview how to evaluate intravascular volumeDiscuss the different types of IV fluidsDiscuss regimens for perioperative fluid and blood replacement therapy
3 Body Fluid Compartments TOTAL BODY WATER (60%)EXTRACELLULAR FLUID(1/3 TBW)INTRACELLULAR FLUID(2/3 TBW)INTERSTITIAL FLUID(3/4 ECF)PLASMA(1/4 ECF)TRANSCELLULAR FLUIDAccurate for children 6 months of age and older
5 Body Fluid Compartments ICF – 2/3 TBWThe proportion of ECF is much greater to that of the ICF in the preterm infants.Upon birth, there is gradual shift from the ECF to the ICF
6 Blood Volumes Preterm 100 ml/kg Term 90 ml/kg Infant 80 ml/kg School Age ml/kgAdult ml/kgSource: A Practice of Anesthesia for Infants and Children by Cote 4th ed
7 Renal System Features of a fetal kidney: low RBF, low GFR Reasons behind these features:1. low systemic arterial pressure2. high renal vascular resistance3. low permeability of glomerular capillaries4. small size and number of glomeruli
8 Renal System 1st 3 -4 days of life: circulatory changes ↑ RBF and ↑GFR 1 month of age: kidneys are 60% mature. This is sufficient to handle almost any contingency.2 yrs: complete maturation of renal function
9 Renal System Implication: “obligate sodium loser” Immature tubular cells cannot completely reabsorb Na+ under the stimulus of aldosterone⇓Neonate continue to excrete Na+ in the urinedespite the presence of a severe Na+ defectImplication: “obligate sodium loser”
10 Renal System: Concentrating Capacity Limited in the neonateMax urine osmolality is only ½ of adult levels ( meq/L vs 1300 – 1400 meq/L)Contributory factors:low circulating ADH levels↓ renal responsiveness to ADH↓ tonicity in the medulary insterstitiumImplication: Increases free water losses duringexcretion of a solute loss
11 Renal System: Diluting Capacity A water-loaded infant can excrete dilute urine with osmolality as low as 50 mOsm/kg.The diluting capacity becomes mature by 3 to 5 weeks of postnatal life.
12 Cardiovascular System relatively low contractile mass/gram of cardiac tissue⇓limited ability to ↑ myocardial contractility↓ in ventricular complianceextremely limited ability to ↑ stroke volumeImplication: need to ↑HR to ↑cardiac output
13 Cardiovascular System cardiac Ca2+ stores are ↓ due to immaturity of sacroplasmic reticulum ⇒ dependent of exogenous Ca2+Implication:Neonatal heart is vulnerable to myocardialdysfunction in the presence of citrate-inducedhypocalcemia
14 Hematologic SystemNeonates have higher baseline Hb values (14 – 20 g/dl)They have a higher percentage of fetal HbAt birth, vitamin K dependent factors are at 20 – 60% of adult levels
15 Neonatal Fluid Management At birth: ECF is greater than ICFA few days after birth:ECF contraction and wt loss due to ANP induced diuresis 2° to ↑ pulmonary blood flow & stretch of left atrial receptorsThis is followed by ↑ water and Na requirements to match those of the growing infantImplication: Fluids should be restricted until the postnatal weight loss has occurred.
16 Neonatal Fluid Management If a baby requires IV fluids from birth, they shld be given 10% dextrose in the following volumesDay 1 60 ml/kg/day DayDay DayDay 3 120Na+ 3 mmol/kg/day & K+ 2 mmol/kg/day shld be added after the postnatal diuresis or if Na+ dropsA premature neonate may require an additional 30 ml/kg/day and additional Na+
17 Neonatal Fluid Management Fluid requirements are titrated to the:patient’s changing weighturine outputserum sodium
18 Evaluation of Intravascular Volume Physical ExaminationLaboratory ExamHemodynamic Measurements
19 Clinical and laboratory assessment of the severity of dehydration in children Signs and SymptomsMild DehydrationModerate DehydrationSevere DehydrationWt loss (%)51015Fluid deficit (ml/kg)50100150Vital SignsPulseNormal↑, weakgreatly ↑, feebleBPNormal to low↓, orthostaticRespirationDeepDeep & rapid
20 Clinical and laboratory assessment of the severity of dehydration in children Signs and SymptomsMild DehydrationModerate DehydrationSevere DehydrationBehaviorNormalIrritableHyperirritable to lethargicThirstSlightModerateIntenseSkin turgorDecreasedGreatly ↓Ant. fontanelleSunkenMarkedly depressedUrine flow (ml/kg/hr)<2<1<0.5Urine SG1.0201.020 – 1.030>1.030
22 Crystalloidssterile aqueous solutions which may contain glucose, various electrolytes, organic salts and nonionic compoundsrapidly equilibrates with ECF
23 Composition of Crystalloids FluidOsmolaritypHNaKClGlucose0.9% NaCl3086.0154LR2736.51304156D5W2524.550D5LR5255.0D5NR5475.21405
24 Crystalloid Solutions 2 ways of classificationa. based on useb. based on tonicity
25 Crystalloid Solutions: Based on Use Maintenance-type solutionswater losshypotonic solutionsReplacement-type solutionswater and electrolyte lossesisotonic electrolyte solutionsFluids for special purposes
26 Crystalloid Solutions: Based on Tonicity Balanced salt solutionselectrolyte composition similar to ECFHypotonic with respect to NaFluidOsmpHNaKOtherLR2736.51304Lactate = 28Normosol2957.41405Mg =3, acetate = 27, gluconate = 23Plasmalyte298.55.5HCO3 = 50
27 Crystalloid Solutions: Based on Tonicity Normal Salineisotonic (6.0) and isoosmotic (308)contains no buffers or electrolyteslarge volume:dilutional hyperchloremic acidosis
28 Crystalloid Solutions: Based on Tonicity Hypertonic Salt SolutionsNa concn range from 250 – 1200 meq/LRapid volume expansion after infusion of small amounts (e.g. 250 mL)t½: similar to isotonic salinemay cause hemolysis at point of injection
29 Glucose containing solutions Glucose—given intravenously—is rapidlymetabolized, leaving free water behinddistributes across all compartments rapidly
31 Final Word on Crystalloids What is the best crystalloid?Isotonic crystalloids are preferred over hypotonic crystalloids
32 Do we have to routinely give glucose containing solutions? Routine dextrose administration is no longer advised for otherwise healthy children receiving anesthesia.There is a growing consensus to selectively administer intraoperative dextrose only in pts at greatest risk for hypoglycemia and in such situations to consider the use of fluids with lower dextrose concentrations (1% or 2.5%)
33 Colloidscontains high MW substances - proteins, large glucose polymersmaintain plasma oncotic pressureintravascular t½: 3 – 6 hrs.
34 Colloids: Classification Natural Protein ColloidAlbumin or Plasma Protein fractionSynthetic Protein ColloidsHetastarchDextransGelatins
35 Albumin Colloid “gold standard” Derived from human pool plasma → heated to 60 C for 10 hrs → ultrafiltrationMW: 69 kDaAvailable as: 5% and 25%Albumin 5% osmotically equivalent to an equal volume of plasma
36 Albumin Use with caution in patients with increased intravascular permeability(e.g. critically ill, sepsis, trauma, burn)
37 Albumin: Side Effect Rare Might still have weak anticoagulation effects through platelet aggregation inhibition or heparin-like effects on antithrombin IIIThese effects are thought to be clinically insignificant if volume replacement with albumin is kept below 25% of the patient’s blood volume.
38 Final word on Albumin Data supporting the continued use of albumin for general fluid resuscitation in children arelacking and in children with traumatic brain injury, itmay actually be harmful. Its utility may exist inspecific subgroups such as neonates and patientsundergoing cardiac surgery.
46 HES: Unwanted Side Effects Hypocoagulable effect- seems to interfere with the function of vWF, factor VIIIand plateletsRenal toxicity- induce renal tubular cell swelling & create hyperviscousurinePruritus- accumulation on HES molecules under the skin
47 Voluven Pediatric dose: mean dose of 16 + 9 ml/kg Contraindication: known hypersensitivity to HESCHF or pulmonary edemarenal failure with oliguria not related to hypovolemiapts receiving dialysis treatmentsevere hyperNa+ or hyperCl+intracranial bleeding
48 Final word on Hetastarch There are still limited clinical trials in children.It appears that the new generation HES are much safer in comparison to the older generation HES.
49 Gelatins polypeptides produced by degradation of bovine collagen ave MW: 30,000 – 35,000 kDarequires repeated infusionsno dose limitation
50 Gelofusine: Pharmaceuticals Characteristics Concentration4%Na154Cl120pH7.4Volume effect100%Duration of vol expansion4 hrs
51 Final word on Gelofusine It has less anaphylactoid and coagulation effect in comparison to HES.The data supporting use of gelatin in children are limited.
59 Transfusion: pRBC MABL of 10-20 % EBV MABL = EBV (pt initial Hct – lowest acceptable Hct)pt initial HctHb: g/dlHct: %Higher target Hct for certain pts
60 Blood Volumes Preterm 100 ml/kg Term 90 ml/kg Infant 80 ml/kg School Age ml/kgAdult ml/kgSource: A Practice of Anesthesia for Infants and Children by Cote 4th ed
61 Problem A 10 yr old 25 kg girl is scheduled to undergo closure of colostomy. Her baseline Hct is 36% and lowest acceptableHct is 21%. What is her MABL?MABL = 1750 x (36 – 21)36= 730 ml
62 ProblemIn the same pt, if the blood loss exceeded the MABL by 150 ml and the target Hct is 30%, how much pRBC will you give?Vol of pRBC = (vol of blood to replace) (target Hct)Hct of blood product= (150) (0.3)0.7= ≈ 65 mlShort cut: ≈ 0.5 ml of pRBC for every ml of blood lossbeyond the MABL if target Hct is 0.3
63 Transfusion: FFP Indication: treatment of isolated factor deficiencies,reversal of warfarin therapy,correction of liver disease associated coagulopathyInitial therapeutic dose: 10–15 mL/kgGoal: 30% of the normal coagulation factorconcentration
64 Transfusion: Platelets Indication:pts with thrombocytopenia or dysfunctional platelets in the presence of bleedingTransfusion threshold:Plt counts less than 50,000 x 109/L