FLUID THERAPY

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FLUID THERAPY

• JoAnne M. Roesner DVM, DABVP
• Loving Hands Animal Clinic
• Alpharetta, GA
• www.lovinghands.com
• joanne.roesner_at_lovinghands.com

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• Thanks to Schering-Plough for sponsoring this
  lecture!

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Body Water and Fluid Compartments

• TBW 0.6 x kg
• TBW ECF ICF
• (1/3) (2/3)
• ECF extracellular, ICF intracellular
• ECF Interstitial Plasma
• (1/3) (1/4)
• Fluid spaces are iso-osmolar due to water
  movement
• (Greco, Vet Clinics, 1998)

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Fluid Movement

• Net filtration at arteriolar end
• Net re-adsorption at venuli end
• Inflammation causes increased vascular
  permeability
• (Greco, Vet Clinics, 1998)

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Why give fluids?

• Replace intravascular volume
• Improve tissue perfusion
• Replace fluid deficits (dehydration)
• Meet maintenance in NPO patient
• Replace ongoing losses (V, D, burns, etc.)
• Fluid diuresis to eliminate toxins
• Anesthetic and surgical support
• Replacement of specific components (blood,
  plasma)
• Nutritional support (TPN, PPN)
• (Mensach IVECCS, 2005)

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Examples of Fluid Loss

• Puregastric vomiting loss of HCl volume causes
  hypochloremic metabolic alkalosis (Cl decrease
  limits re-adsorption of HCO3 in kidneys
• Bilious vomiting loss of K, HCO3, Na causes
  hypokalemia, acidosis (Color of vomit is
  important!)
• Panting loss of free water no electrolyte loss
• PD free water gain dilution and diuresis
  promote ion loss
• Diarrhea volume Na, K, HCO3

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Routes of Fluid Administration

• Subcutaneous
• - not for sever dehydration or shock
• - not if potential vasoconstriction
• - crystalloids only
• - no dextrose
• - K is painful
• - 10-20 ml/kg/site
• - aseptic technique

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Routes of Fluid Administration

• Enteral
• - limited by patients ability to handle
• - can use to prevent gut-atrophy
• - trickle feeding
• - can combine with other methods (NG tube, etc.)
• - BES K dextrose food coloring
• Intraperitoneal
• - fairly rapid adsorption
• - aseptic technique
• - warm fluids
• (Mensach, IVECCS, 2005 Matthews, Vet Clinics,
  1998.)

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Routes of Fluid Administration

• Intraosseous
• - similar to IV
• - useful especially in neonates and small
  patients
• Intravenous
• - peripheral vs. central line
• - moderate/severe dehydration, shock
• - cutdowns (20G needle technique)
• - change catheters every 72 hours
• - CVP ballparking it
• - bolus vs. CRI
• - crystalloids, colloids, blood products, IV
  feeding
• (Mensach, IVECCS, 2005 Matthews, Vet Clinics,
  1998)

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Maintenance Fluid Rates

• Only an estimate
• Consider sensible (urine, feces) and insensible
  fluid losses
• Do not consider other potential losses (PUPD, V,
  D)
• Calculations
• 1 ml/lb/h
• 66 ml/kg/d for dogs
• 44 ml/kg/d for cats
• 30 ml/lb/day
• (30 x kg) 70 (also RER)
• Measure ins and outs and add 2 ml/kg/hr for
  insensible

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Fluid Deficits

• Replace with BES (type determined by source of
  losses)
• Replace over 24 hours (in addition to maintenace
  route)
• Rapid replacement can result in cerebral edema
  when losses are chronic (idiogenic osmoles)
• Deficit (ml) dehydration x kg x 1000
• (Matthews, Vet Clinics, 1998)

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Shock Fluid Rates

• Goal is rapid repletion of vascular volume
• Best to use physiologic endpoints rather than
  rote formula (BP, HR, CRT, etc.)
• Dog up to 90 ml/kg crystalloid
• Cat up to 40 ml/kg crystalloid
• Consider adding colloids, hypertonic saline

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Intra-operative Fluid Rates

• 5 ml/kg/h for procedures involving minimal blood
  loss
• 10 ml/kg/h for more extensive procedures or those
  with greater blood loss
• (Mensach, IVECCS, 2005)

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Monitoring Fluid Therapy

• Serial exams vascular fullness, membrane
  moisture, skin turgor, auscultation, CRT, pulse
  quality, HR, RR
• Urine specific gravity, volume
• Blood pressure
• Body weight
• Labs electrolytes, PCV, TS, BUN, Creatinine,
  lactate (tissue perfusion)
• CVP
• (Mensach, IVECCS, 2005 Hughes, IVECCS, 2005)

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Serum Electrolytes

• SODIUM
• Extracellular major determinant of plasma
  tonicity, low Na means too much free water in
  blood, high Na means too little free water, must
  address abnormalities to prevent brain swelling
  or shrinking
• ADH released from posterior pituitary in
  response to increased plasma osmolarity, causes
  water re-adsorption in kidney
• Aldosterone released from adrenal gland, causes
  water re-adsorption in kidney, Na conservation, K
  excretion
• (Dibartola, Marks, Vet Clinics, 1998)

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Serum Electrolytes

• CHLORIDE
• Primary extracellular anion
• Levels typically parallel Na
• Low Cl prevents HCO3 re-adsorption in kidney and
  exacerbates alkalosis
• (Dibartola, Marks, Vet Clinics, 1998)

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Serum Electrolytes

• POTASSIUM
• Intracellular cation, Na K ATPase (Mg cofactor)
• Hypokalemia common, especially in cats
• Maximum rate of administration 0.5 mEq/kg/h
• Maintenace is 20 mEq/L of BES
• Translocation alters serum levels (e.g. acidosis
  causes movement out of cells, insulin causes
  movement into cells)
• Aldosterone promote K excretion (Na re-adsorption)

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Serum Electrolytes

• POTASSIUM
• Low Mg promotes K excretion
• Serum levels do not reflect body stores
• Low K weakness, droopy neck, long QT, interval,
  decreased T waves
• High K weakness, spiked T waves, wide QRS,
  decreased P waves
• (Phillips and Polzin, Vet Clinics, 1998)

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Serum Electrolytes

• MAGNESIUM
• Most common electrolyte abnormality n
  hospitalized humans is hypomagnesimia
• Primarily intracellular
• Low Mg may be clinically silent but makes
  hypocalcemia and hypokalemia refractory to
  treatment
• Vitamin D controls Mg absorption
• May see high Mg in renal failure

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Serum Electrolytes

• MAGNESIUM
• Normosol and Plasmalyte contain Mg
• Very low Mg may require treatment with IV MgSO4
• Cofactor for NaK ATPase
• (Martin, Vet Clinics, 1998 Dhupa and Proulx, Vet
  Clinics, 1998)

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Serum Electrolytes

• BICARBONATE
• Major plasma buffer along with proteins
• Metabolic component of acid/base disorders
• Will precipitate with Ca (do not add to LRS)
• Mild abnormalities resolve with fluid repletion
  and improved perfusion
• Always under correct base deficits (organic acids
  are metabolized with improved perfusion i.e.
  dont need to neutralize)
• Normal dogs 18-24
• (Bailey and Pablo, Vet Clinics, 1998)

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Serum Electrolytes

• PHOSPATE
• Hyperphosphatemia common in CRF, can occur with
  primary parathyroid disease and cancer (PTHrp)
• Hypophosphatemia seen with diuresis, TPN,
  hepatic lipidosis, treated DKA (especially cats)
  alkalosis
• Clinical signs may be profound
• - neuro, cardiac, hemolysis (ATP, 2-3 DPG etc.
  mediated)
• - Therapy/prevention replace half of daily K as
  K2PO4
• - Enteral cows milk

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Types of Fluids

• Crystalloids replacement solutions, maintenance
  solutions, hypertonic saline
• D5W
• Colloids
• Blood products
• TPN and PPN
• (Matthews, Vet Clinics, May 1998 Mensach, 11th
  IVECCS Proceedings, 2005)

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Crystalloids

• Water with Na or glucose, base source,
  electrolytes
• Short intravascular retention equilibrate with
  intracellular and interstitial compartments
• Base source (NaCO3-)
• lactate liver metabolism
• acetate muscle metabolism
• gluconate metabolism in most body tissue
• (Matthews, Vet Clinics, May 1998 Mensach 11th
  IVECCS Proceedings, 2005)

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Tonicity

• Isotonic approximate osmolarity of blood and
  ECF, does not cause swelling or shrinking of RBC
  when infused (e.g. LRS)
• Hypertonic osmolarity higher than ECF and blood,
  can shrink RBC and dehydrate intracellular and
  interstitial fluid
• Hypotonic osmolarity lower than ECF and blood,
  may swell RBC and cause edema
• (Matthews, Vet Clinics, May 1998 Mensach, 11th
  IVECCS 2005)

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Replacement Solutions

• Either alkalinizing or acidifying
• Solute concentration plasma water concentration
• Used to rapidly replace intravascular fluid and
  electrolytes (e.g. GI disease, 3rd spacing, /-
  hemmorrhage, shock), used to replace fluid
  deficits
• 20-25 stays within vascular space 1 hour post
  infusion

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Replacement Solutions

• Consider source of loss (e.g. pure gastric vs.
  bilious vomiting) when choosing a fluid
• Fluid deficit (liters) dehydration x kg
• Examples
• LRS
• 0.9 NaCl
• Plasmalyte A
• Normosol-R
• (Matthews, Vet Clinics, May 1998 Mensach, 11th
  IVECCS 2005)

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Lactated Ringers Solution (LRS)

• Isotonic
• Alakalinzing 28 mEq/L of bicarb precursors
• Na lower than plasma (130 mEq/L)
• K is low (4 mEq/L)
• No Mg2
• Cl- is relatively high (119 mEq/L0
• Ca2 is 3 mEq/L
• (Matthews, Vet Clinics, May 1998, p. 483)

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Lactated Ringers Solution (LRS)

• Lactate must be metabolized in liver, may already
  be high in patient with hypoperfusion
• Calcium will precipitate if add NaHCO3, chelating
  anticoagulants and some drugs
• Consider adding 16 mEq/L KCL if used as a
  maintenance fluid (i.e. total 20 mEq/L K)
• Add free water source if used as maintenace
• Useful choice for diuresis replacement of
  isotonic or slightly hypotonic fluid losses,
  vascular volume repletion
• (Matthews, Vet Clinics, May 1998, p. 483)

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L-LRS vs. Raceemic (D-L) LRS

• Most LRS is racemic
• L-LRS is available from Baxter
• D-isomer is pro-inflammatory
• L-isomer is not inflammatory
• Ketone Ringers (betahydroxybutyrate relace
  lactate as buffer) also less inflammatory
• (Wall, IVECCS, 2005)

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Ringers Ethyl Pyruvate

• Better restoration of splanich flow
• Decreased intestinal hyperpermeability
• Decrease NF Kappa B activation
• (Wall, IVECCS, 2005)

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Normal Saline (0.9 NaCl)

• Isotonic, acidifying
• Na and Cl 154 mEq/L
• No Ca or Mg
• Can add HCO3, PO4 safely
• Useful to treat alkalosis (pure gastric vomiting,
  furosemide overdose)
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Normal Saline (0.9 NaCl)

• Useful to treat hypercalcemia and hyperkalemia
  (Addisons) and bodywide Na depletion
  (diabetes/DKA) and initially in sever
  hypernatremia
• May need potassium supplement contra-indicated in
  volume overload (CHF, hypertension, liver disease
  with Na retention)
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Normosol R

• Isotonic
• - Na 140 mEq/L
• - K 5 mEq/L
• - Cl 98 mEq/L
• - Mg 3 mEq/L
• May add HCO3, PO4, some alkalinizing drugs
• Acetate is buffer (16 mEq/L)
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Normosol R

• Useful in a wide variety of situations
• Useful in liver disease because acetate is
  metabolized in muscle
• Not enough Mg to treat hypomagnesemia but may
  prevent it
• Use cautiously with renal disease as Mg may
  already be high
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Maintenance Solutions

• Use after fluid deficits have been replaced
• Solute concentration approximates ECF, meets
  normal maintenace losses
• Hypotonic
• Less than 10 remains in vascular space after 1
  hour
• Most need potassium supplementation
• e.g. Normosol M, Plasmalyte 56, 0.45 NaCl and
  1/2 D5W and LRS
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Hypertonic Saline

• 7.5-23 NaCl
• Used to rapidly expand vascular volume (e.g.
  severe hypovolemia with impending death, low
  volume resuscitation in head trauma, GDV (cannot
  get fluids in fast enough))
• Dogs 4-8 ml/kg, cats 204 ml/kg at 1 ml/kg/minute
• Lasts 30 minutes intravascularly
• Follow with crystalloids, colloids
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Hypertonic Saline

• Contra-indications dehydration, heart or liver
  disease, uncontrolled hemorrhage
• Monitor cardiovascular parameters (negative
  inotrope, lasts for approximately 10 minutes
  post-infusion)
• May decrease re-perfusion injury by reducing
  calcium entry into cells
• Decreases endothelial swelling and dysfunction
• Can combine with colloids
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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D5W

• Isotonic
• Source of free water
• NOT balanced (No Na, K, Mg, Cl)
• No buffer source
• Vehicle for drug infusion
• Not a significant calorie source
• Used with mixed replacement solutions to create
  maintenace fluids
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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D5W

• Free water deficit
• Liters 0.6 x kg ((1-42)/Patient Na)
• Plasma osmolality 2(Na K) BUN/18 Glucose
• (DiBartola, Vet Clinics, 1998 Marks and Taboada,
  Vet Clinics, 1998.)

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Colloids

• Contain large molecules which do not diffuse
  freely from intravascular compartment
• Oncotic pressure proportional to number of
  particles
• Expand vascular volume
• Hypovolemic resuscitation (e.g. head trauma, 3rd
  spacing)
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Colloids

• Inflammatory disease (pancreatitis, SIRS, sepsis,
  etc.)
• Synthetic and natural
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Colloids

• Relatively contra-indicated in CHF or
  oliguric/anuric RF
• May decrease clotting factor activity with
  synthetic colloids, but low clinic risk with
  products available currently
• Monitor if use synthetic colloids in patients
  with pre-existing coagulopathy

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Capillary Leak Syndrome

• Present in inflammation
• Results in tissue edema -gt organ dysfunction -gt
  MODS
• Colloids help ameliorate via plug endothelial
  gaps with large molecule, down regulate adhesins
  (e.g. ICAM-1, ? selectin)
• (Chan, IVECCS, 2005)

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Plasma

• Midwest Animal Blood Services Inc.
• [phone]
• Feline FFP 25 ml/unit 110 (4/05)
• Canine FFP 210 ml/unit 165
• Canine Cryopoor P 100ml/unit 66
• Shelf life is one year

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Plasma

• FFP all clotting factors, ATIII alpha-2
  macroglobulin, etc. albumin
• Cryopoor Plasma lacks factor VIII etc., still
  has albumin, other clotting factors (ATIII)
• 22.5 ml/kg of plasma will raise patient albumin
  5g/L
• May need to combine with sythetic colloids in
  inflammation
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Plasma

• Controversial incubate with heparin (10-100
  u/kg) for 30 minutes in DIC
• Volume 20-30 ml/kg/day
• Infuse over 4-24 hours
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Albumin

• Source of oncotic pressure in plasma
• Leaks in inflammation
• 1 g albumin retains 18 ml of fluid in
  intravascular space
• Normal distribution 40 intravascular, 60
  interstitial
• Hepatic synthesis regulated by osmoreceptors in
  interstitium, not by blood levels
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Albumin

• t ½ 8-9 days in man
• Carries drugs and endogenous substanecs
• Scavenges free radicals, reactive oxygen species,
  Fe
• Helps to maintain vascular integrity
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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25 Human Serum Albumin (HAS)

• May have anti-inflammatory benefit (decreased
  macrophage activation and PMN oxygen burst, CD 18
  down regulation)
• Use peripheral or central line
• OVC in Geulph 200 cases 2-4 ml/kg at rate of
  0.1-1.7 ml/kg/h, monitor BP, HR, RR, T, edema,
  anaphylaxis
• Plasbumin Bayer
• Long-term effects still under investigation
• (Matthews, Vet Clinics, May 1998 Mensach,
  IVECCS, 2005)

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Hetastarch (HES)

• Synthetic colloid, plant starch
• Degraded by amylase, rate is proportional to
  degree of hydroxyl substitution
• Dogs at 20 ml/kg/day say changes in clotting
  tests but no clinical effects
• USA 6 HES (450 KDa/0.7 C2C6)
• Europe lower MW higher substitution products
• ? less coagulation change, balanced electrolyte
  solution ? less inflammatory
• (Chan, IVECCS, 2005)

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Hetastarch (HES)

• Dose
• Dog 20 ml/kg/day (up to 40 ml/kg/day)
• Cat 5-10 ml/kg/day
• After initial volume administration can mix with
  crystalloids in a ratio of 30 HES70
  crystalloid x rate of fluids
• Monitor for overhydration with all synthetic
  colloids
• (Matthews, Vet Clinics, 1998 Chan, IVECCS, 2005.)

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Hemoglobin Based Oxygen Carriers (HBOCs)

• Oxyglobin Biopure
• Hemopure Biopure (future product?)
• PolyHeme Northfield Labs (under development)
• Sangart Product (under development)
• (Wall, IVECCS, 2005)

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HBOC Oxyglobin

• Bovine Hb solution
• Unloads O2 according to Cl tension
• Access to microcucultation (smaller than RBC)
• Potent colloid give slowly and at lower volume
  than in cats
• Stable at room temperature
• Do not freeze
• (Matthews, Vet Clinics, 1998 Mensach, IVECCS,
  2005 Wall, IVECCS, 2005.)

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HBOC Oxyglobin

• Forms methemoglobin with storage after opening
• Dose 10-30 ml/kg (dog)
• Discolors urine and patient
• Interferes with some lab tests
• (Matthews, Vet Clinics, 1998 Mensach, IVECCS,
  2005 Wall, IVECCS, 2005)

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Total Parenteral Nutrition (TPN)

• Meet total caloric needs via IV solutions
• Must use central line
• Absolute aseptic technique
• Gut atrophy and bacterial/toxin translocators
• Hypertonic solutions, lipid containing
• Complications vasculitis, thrombosis
• Ebb and flow phases of stressed starvation
  (hypermetabolism)
• (Mazzaferro, Multidisciplinary Review, 2004)

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Partial Parenteral Nutrition (PPN)

• Use to meet part of RER
• Aminoacids, electrolytes (K, Mg, PO4)
  carbohydrates /- lipids
• Peripheral line if lt 5.50 mOsm/L dedicated line
  is best (my preference is BES 1 line PPN in 2nd
  line at maintenance rate)
• Need to monitor electrolytes
• Add B vitamins
• (Mazzaferro, 2004 Matthews, Vet Clinics, 1998
  Mensach, IVECCS, 2005)

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Partial Parenteral Nutrition (PPN)

• RER (30 x kg) 70, goal 25-50 RER
• Give energy via Dextrose (80-100) lipids (20)
• Dog 3g protein per 100 Kcal
• Cat 4 g protein per 100 Kcal, add taurine
• Consider adding Mg (0.75 mEq/kg/day), PO4 (add ½
  of supplemental K requirements as K2PO4) and K
• 5 Dextrose (100 ml 50 ex to 900 ml BES 0.17
  Kcal/ml)
• Lipid 20 2 Kcal/mo, 8.5 amino acid .085
  g/ml
• (Mazzaferro, 2004)

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PPN Products

• 10 Aminosyn 13.64/500 ml
• amino acid only, need to dilute in maintenace
  fluids to give peripherally, need to add CHO
  source and dilute
• Procalamine amino acids, some electrolytes and
  glycerol, hard to find (old price 40/L)
• Freeamine amino acids and electrolytes (NOT BES,
  low NaCl), can add 50 dextrose to make a 5
  solution
• (Mensach, IVECCS, 2005. Matthews, Vet Clinics,
  1998)

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PPN Recipe

• Remove 100 ml from 1 L bag of Normosol M
• Add 100 cc 50 dextrose to yield 5 dextrose in
  Normosol M
• Remove 330 ml of fluid from above
• Add 330 ml of amino acid solution to above (e.g.
  Travasol)
• Final solution is
• 3.3 amino acid (33g protein) 50 mEq/L Cl
• 3.3 dextrose (33g dextrose) 20 mEq/L PO4
• 30 mEq/L KCl 5 mEq/L Mg
• 45 mEq/L Na 650 mOsm/L
• (Matthews, Vet Clinics, 1998)

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References

• Vet Clinics of North America Advances in Fluid
  Therapy, May 1998
• a. Distribution of Body Water and General
  Approach to the Patient. Greco, p. 473.
• b. Various Types of Parenteral Fluids and Their
  Indicators. Matthews, p. 483.
• c. Fluid Therapy in Shock. Mandell and King, p.
  623.
• d. Hyponatremia. DiBartola, p. 515.
• e. Hypernatremia. Marks and Taboada, p. 533.

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References

• f. Clinical Disorders of Potassium Homeostasis.
  Phillips and Polzin, p. 545.
• g. Hypercalcemia and Hypermagnesimia. Martin, p.
  565.
• h. Hypocalcemia and Hypomagnesimia. Dhupa and
  Proulx, p. 587.
• 2. Proceedings 11th IVECCS Symposium, Sept. 2005.
• a. Fluid Therapy Options and Rational
  Selection. Mensach, p. 389.

63
References

• b. Update on Synthetic and Natural Colloids.
  Chan, p. 395.
• c. Designer Fluid Therapy. Wall, p. 405.
• d. Clinical Use of 25 Human Serum Albumin in
  Veterinary Patients. Mathews, p. 411.
• e. Clinical Use of Serum Lactate. Hughes, p.
  173.
• 3. Multidisciplinary Systems Review, Proceedings
  10th IVECCS Symposium, September 8, 2004.
• a. Nutritional Requirements of the Critically
  Ill Patient. Mazzaferro, p. 1.