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PEDIATRIC PERIOPERATIVE FLUID THERAPY

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Presentation on theme: "PEDIATRIC PERIOPERATIVE FLUID THERAPY"— Presentation transcript:

1 PEDIATRIC PERIOPERATIVE FLUID THERAPY
Evangeline Ko-Villa, MD, DPBA Clinical Associate Professor UP-PGH Department of Anesthesiology

2 Objectives Review relevant physiological considerations in the pediatric population Review how to evaluate intravascular volume Discuss the different types of IV fluids Discuss 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 FLUID Accurate for children 6 months of age and older

4 Body Fluid Compartments
(%)

5 Body Fluid Compartments
ICF – 2/3 TBW The 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/kg Adult ml/kg Source: 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 pressure 2. high renal vascular resistance 3. low permeability of glomerular capillaries 4. 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 urine despite the presence of a severe Na+ defect Implication: “obligate sodium loser”

10 Renal System: Concentrating Capacity
Limited in the neonate Max 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 insterstitium Implication: Increases free water losses during excretion 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 compliance extremely limited ability to ↑ stroke volume Implication: 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 myocardial dysfunction in the presence of citrate-induced hypocalcemia

14 Hematologic System Neonates have higher baseline Hb values (14 – 20 g/dl) They have a higher percentage of fetal Hb At birth, vitamin K dependent factors are at 20 – 60% of adult levels

15 Neonatal Fluid Management
At birth: ECF is greater than ICF A few days after birth: ECF contraction and wt loss due to ANP induced diuresis 2° to ↑ pulmonary blood flow & stretch of left atrial receptors This is followed by ↑ water and Na requirements to match those of the growing infant Implication: 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 volumes Day 1 60 ml/kg/day Day Day Day Day 3 120 Na+ 3 mmol/kg/day & K+ 2 mmol/kg/day shld be added after the postnatal diuresis or if Na+ drops A 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 weight urine output serum sodium

18 Evaluation of Intravascular Volume
Physical Examination Laboratory Exam Hemodynamic Measurements

19 Clinical and laboratory assessment of the severity of dehydration in children
Signs and Symptoms Mild Dehydration Moderate Dehydration Severe Dehydration Wt loss (%) 5 10 15 Fluid deficit (ml/kg) 50 100 150 Vital Signs Pulse Normal ↑, weak greatly ↑, feeble BP Normal to low ↓, orthostatic Respiration Deep Deep & rapid

20 Clinical and laboratory assessment of the severity of dehydration in children
Signs and Symptoms Mild Dehydration Moderate Dehydration Severe Dehydration Behavior Normal Irritable Hyperirritable to lethargic Thirst Slight Moderate Intense Skin turgor Decreased Greatly ↓ Ant. fontanelle Sunken Markedly depressed Urine flow (ml/kg/hr) <2 <1 <0.5 Urine SG 1.020 1.020 – 1.030 >1.030

21 Choice of fluids Crystalloids Colloids Blood products Whole blood pRBC
FFP Platelets

22 Crystalloids sterile aqueous solutions which may contain glucose, various electrolytes, organic salts and nonionic compounds rapidly equilibrates with ECF

23 Composition of Crystalloids
Fluid Osmolarity pH Na K Cl Glucose 0.9% NaCl 308 6.0 154 LR 273 6.5 130 4 156 D5W 252 4.5 50 D5LR 525 5.0 D5NR 547 5.2 140 5

24 Crystalloid Solutions
2 ways of classification a. based on use b. based on tonicity

25 Crystalloid Solutions: Based on Use
Maintenance-type solutions water loss hypotonic solutions Replacement-type solutions water and electrolyte losses isotonic electrolyte solutions Fluids for special purposes

26 Crystalloid Solutions: Based on Tonicity
Balanced salt solutions electrolyte composition similar to ECF Hypotonic with respect to Na Fluid Osm pH Na K Other LR 273 6.5 130 4 Lactate = 28 Normosol 295 7.4 140 5 Mg =3, acetate = 27, gluconate = 23 Plasmalyte 298.5 5.5 HCO3 = 50

27 Crystalloid Solutions: Based on Tonicity
Normal Saline isotonic (6.0) and isoosmotic (308) contains no buffers or electrolytes large volume: dilutional hyperchloremic acidosis

28 Crystalloid Solutions: Based on Tonicity
Hypertonic Salt Solutions Na concn range from 250 – 1200 meq/L Rapid volume expansion after infusion of small amounts (e.g. 250 mL) t½: similar to isotonic saline may cause hemolysis at point of injection

29 Glucose containing solutions
Glucose—given intravenously—is rapidly metabolized, leaving free water behind distributes across all compartments rapidly

30 Crystalloids Advantages Disadvantages Inexpensive
Very low incidence of adverse reactions Disadvantages Short lived hemodynamic improvement (intravascular t½: 20 – 30 mins.) Peripheral/pulmonary edema

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 Colloids contains high MW substances - proteins, large glucose polymers maintain plasma oncotic pressure intravascular t½: 3 – 6 hrs.

34 Colloids: Classification
Natural Protein Colloid Albumin or Plasma Protein fraction Synthetic Protein Colloids Hetastarch Dextrans Gelatins

35 Albumin Colloid “gold standard”
Derived from human pool plasma → heated to 60 C for 10 hrs → ultrafiltration MW: 69 kDa Available 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 III These 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 are lacking and in children with traumatic brain injury, it may actually be harmful. Its utility may exist in specific subgroups such as neonates and patients undergoing cardiac surgery.

39 Hetastarch modified natural polysaccharides Amylopectin Hetastarch

40 Hetastarch Described in terms of: Concentration Average mean MW
Molar substitution C2:C6 ratio

41 Hetastarch: Concentration
Definition – grams in 100 ml Available as: 3%, 6% and 10%

42 Hetastarch: average mean MW
Low - <70 kDa Medium – 270 kDa High - >450 kDa higher MW ⇒ longer volume effect ⇒ greater side effect

43 Hetastarch: Molar Substitution
Definition: CH3CH2OH : glucose units Low (0.4 – 0.5) High (0.62 – 0.7) higher MS ⇒ longer volume effect ⇒ greater side effect

44 Hetastarch: C2:C6 ratio Hydroxyethyl group attached at C2 hinder breakdown Higher ratio of C2:C6 ⇒ in slower enzymatic degradation and prolonged action without increasing side effects.

45 HES Solutions Properties and Availability
Trade Name Hespan® Hextend® Voluven ® Availability Europe/US US Concn 6 Volume effect (h) 5 – 6 2 – 3 1 – 2 MW 450 670 130 70 MS 0.7 0.75 0.4 0.5 C2:C6 ratio 4:1 9:1

46 HES: Unwanted Side Effects
Hypocoagulable effect - seems to interfere with the function of vWF, factor VIII and platelets Renal toxicity - induce renal tubular cell swelling & create hyperviscous urine Pruritus - accumulation on HES molecules under the skin

47 Voluven Pediatric dose: mean dose of 16 + 9 ml/kg Contraindication:
known hypersensitivity to HES CHF or pulmonary edema renal failure with oliguria not related to hypovolemia pts receiving dialysis treatment severe 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 kDa requires repeated infusions no dose limitation

50 Gelofusine: Pharmaceuticals Characteristics
Concentration 4% Na 154 Cl 120 pH 7.4 Volume effect 100% Duration of vol expansion 4 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.

52 Colloids Advantages Disadvantages Smaller infused volume
Prolonged increase in plasma volume Minimal peripheral edema Disadvantages Expensive Coagulopathy Pulmonary edema Anaphylactoid reactions

53 Perioperative Fluid Therapy
Vol of fluid = maintenance fluid requirement + deficit + loss

54 Estimating Maintenance Fluid Requirements
0 – 10 kg ml/kg/hr 11 – 20 kg Add 2 ml/kg/hr > 20 kg Add 1 ml/kg/hr

55 Preexisting Deficits Overnight fasting Preoperative bleeding Vomiting
Diuresis Diarrhea Other insensible losses

56 Surgical Fluid Losses Blood loss Third space loss Evaporation

57 Redistribution and Evaporative Surgical Fluid Losses
DEGREE OF TISSUE TRAUMA ADD’L FLUID REQUIREMENT Minimal ml/kg/hr Moderate ml/kg/hr Severe ml/kg/hr

58 Blood Product Transfusion
What? When? How much?

59 Transfusion: pRBC MABL of 10-20 % EBV
MABL = EBV (pt initial Hct – lowest acceptable Hct) pt initial Hct Hb: g/dl Hct: % Higher target Hct for certain pts

60 Blood Volumes Preterm 100 ml/kg Term 90 ml/kg Infant 80 ml/kg
School Age ml/kg Adult ml/kg Source: 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 acceptable Hct is 21%. What is her MABL? MABL = 1750 x (36 – 21) 36 = 730 ml

62 Problem In 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 ml Short cut: ≈ 0.5 ml of pRBC for every ml of blood loss beyond 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 coagulopathy Initial therapeutic dose: 10–15 mL/kg Goal: 30% of the normal coagulation factor concentration

64 Transfusion: Platelets
Indication: pts with thrombocytopenia or dysfunctional platelets in the presence of bleeding Transfusion threshold: Plt counts less than 50,000 x 109/L

65 THANK YOU


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