IV Fluids

IV Fluids

David Ray Velez, MD

Table of Contents

Crystalloids
Colloids

Crystalloids

Definition: Aqueous Solutions Containing Mineral Salts and Small Molecules

Types

  • Unbalanced Crystalloids:
    • 9% Normal Saline (NS)
    • Hypertonic Saline
      • 3% Normal Saline
      • 4% Normal Saline
    • 45% Normal Saline (1/2 NS)
    • Free Water – Generally Not Given by Itself without Other Additives (D5W, Sodium Bicarbonate, etc.)
  • Balanced Crystalloids: Contain Multiple Electrolytes in Addition to Sodium and Chloride
    • Lactated Ringer (LR)/Hartmann’s Solution
    • Plasma-Lyte/Normosol
  • Common Additives:
    • Dextrose
    • Potassium Chloride (KCl)
    • Sodium Bicarbonate

Normal Saline (NS)

  • Historically the Most Commonly Used Crystalloid
  • Concentrations:
    • 9% Normal Saline (NS)
    • Hypertonic Saline
      • 3% Normal Saline
      • 4% Normal Saline
    • 45% Normal Saline – 1/2 NS
  • Osmolarity:
    • 9% NS is Actually Hypertonic (Not Isotonic)
    • The Preferred Crystalloid in Traumatic Brain Injury (TBI) – Decreased Mortality in TBI Compared to Balanced Crystalloids
  • Acid-Base Effects:
    • Excess Chloride Decreases the SID (Strong Ion Difference)
    • Decreased SID Causes Increased Hydrogen Concentration and Acidosis
  • Additional Negative Effects:
    • Acidosis Causes Potassium Shift Out of Cells
      • NS Causes More Hyperkalemia than LR, Despite the K Concentration in LR
    • Decreased Renal Blood Flow and Higher Risk for Adverse Kidney Events
    • Promotes Inflammation

Lactated Ringer (LR)/Hartmann’s Solution

  • The Most Commonly Used Balanced Crystalloid
  • Electrolyte Concentrations:
    • Lower Sodium and Chloride than NS
    • Contains Potassium
    • Contains Calcium – The Preferred Agent in Hypocalcemia
    • Does Not Contain Magnesium
  • Acid-Base Effects:
    • Lactate is Not the Same as “Lactic Acid” and Does Not Cause Lactic Acidosis
    • Lactate is Metabolized by the Liver into Bicarbonate (Alkalinization)
  • Contraindications:
    • Traumatic Brain Injury (TBI) and Elevated ICP – Due to Low Osmolarity
    • Hypercalcemia – Due to Calcium Concentration
  • Use with Blood Transfusion:
    • Previously Contraindicated with Blood Transfusions, Believing Calcium Could React with Citrate from the Transfusion and Cause Blood Clots
    • Controversial – Newer Data Shows Safety

Plasma-Lyte/Normosol

  • Electrolyte Concentrations:
    • Higher Sodium and Potassium Concentrations than LR
    • Contains Magnesium – Cannot Treat Hypomagnesemia but May Help Prevent
    • Does Not Contain Calcium
  • Acid-Base Effects:
    • Acetate and Gluconate are Metabolized into Bicarbonate
      • Gluconate is Mostly Excreted Unchanged in the Urine with Less Effect
    • Slightly More Alkalinizing than LR
  • Additional Gluconate Effects:
    • Osmotic Diuretic Excreted in the Urine
    • A Portion Can Be Metabolized into Glucose
  • No Studies Directly Comparing LR and Plasmalyte
  Normal Levels NS LR Plasma-Lyte
Na 135-145 154 130 140
Cl 96-106 154 109 98
K 3.5-5.2 4 5
Ca 8.5-10.2 2.7
Mg 1.7-2.2 1.5
Lactate 28
Acetate 27
Gluconate 23
Osmolarity 285 308 274 295
Strong Ion Difference (SID) 0 28 49

Colloids

Definition: Aqueous Solutions Containing Large Molecules

Types

  • Natural Colloids:
    • Packed Red Blood Cells (PRBC)
    • Platelets (Plt)
    • Plasma (FFP)
    • Albumin
  • Synthetic Colloids:
    • Hydroxyethyl Starch
    • Dextran
    • Gelatins

Blood Products

  • *See Blood Products

Albumin

  • Physiology:
    • In Healthy Persons:
      • Increases Oncotic Pressure
      • Expands the Plasma Volume
      • Less Third Spacing (Pulmonary Edema, Abdominal Compartment Syndrome)
    • Capillary Leak is High in Critically Ill Patients and Albumin is Lost to the Tissues without the Desired Effect
    • May Stay Intravascular Longer but Does Not “Pull” Fluid In
  • Clinical Use:
    • High Variability in Use with Poorly Defined Indications
    • Should Be Used as an Adjunct When Receiving High-Volume Crystalloid Resuscitation and Not the Sole Resuscitative Fluid
    • Sepsis/Septic Shock – No Mortality Benefit but Higher MAP (Off Vasopressors Sooner) and Lower Net Fluid Requirement
    • Burn Injury – May Have Decreased Mortality and Risk of Compartment Syndrome
    • Cirrhosis – Used in Select Situations (Post-Paracentesis, SBP, or Hepatorenal Syndrome)
    • Hypoalbuminemia – No Benefit and May Actually Increase Mortality
    • Traumatic Brain Injury – Increases ICP and Mortality (Considered an Absolute Contraindication)
  • Dosing:
    • Albumin 25% – Generally Preferred When Fluid is Restricted or When Using for Oncotic Deficiencies
      • The Most Commonly Used Formulation in Critical Illness
    • Albumin 5% – Generally Used When Being Given as the Sole Fluid for Volume Loss

Synthetic Colloids

  • Agents:
    • Hydroxyethyl Starch (HES/Hetastarch)
    • Dextran
    • Gelatins
  • Rarely Used in Modern Practice Due to Risk of AKI and Coagulopathy (From Impaired Platelet Function)