IV Fluids Flashcards
Things to Consider with IV Fluids
Why an IV?
Know your patient: age, heart/lung/kidney problems
Watch for signs of dehydration
Monitor: weight, BP, HR, BMP, & urine output
Disorders of Volume in a Surgical Patient
Depletion
Excess
Disorders of Electrolyte Concentrations
Sodium Potassium Chloride Calcium Magnesium Phosphate
Sequelae of Inappropriate Fluid & Electrolyte Management
Increased length of stay Increased cost Wound infection Delayed wound healing Anastomotic failure Tachyarrhythmias Cerebral edema, seizures, death Pulmonary edema, CHF, renal failure
3 Things to Accomplish with IV Therapy
Maintenance therapy
Replacement therapy
Volume resuscitation
Reason for Maintenance Therapy
Patient not expected to eat or drink for a while
Reason for Replacement Therapy
Correct abnormalities in volume and/or electrolytes
Reasons for Volume Resuscitation
Hypotension
Hemorrhage
What does total body water depend on?
Age
Gender
Muscle mass
Fat
Total Body Water as a % of Weight Decreases in
Morbidly obese individuals
Elderly
People with low muscle mass due to disease or injury
How much of total body weight does the intracellular fluid hold?
2/3
How much of total body weight does the extracellular fluid hold?
1/3
What does the plasma portion of the ECF contain?
Main: Na+
Cations: K+, Ca++, Mg++
Anions: Cl-, HCO3-, proteins, sulfates, organic acids
What does the ICF contain?
Main: K+, Mg++
Anions: phosphates, sulfates, & proteins
What can flow freely among all of the compartments in the body?
Water
Normal Body Fluid Osmolarity
285 osmol/L
Types of Fluid Replacement Products
Crystalloids
Colloids
Types of Crystalloids
Dextrose in water
Saline
Combination
Ringer’s Lactate (physiologic)
Examples of Colloids
Albumin Dextran Hetastarch Blood FFP
Define Crystalloid
Solution that contains small molecules & are able to pass through semi-permeable membranes
Define Colloid
Solutions that contain high molecular weight proteins or starch
Can not cross semi-permeable membranes
Remain in the intravascular space
When are colloids indicated?
Rapid hemodynamic equilibration is required
What is important when addressing a specific situation?
Composition of the solution
Rate of administration
Why are isotonic solutions given?
To expand the ECF volume
Why are hypotonic solutions given?
To reverse dehydration
Why are hypertonic solutions given?
To increase the ECF volume & decrease cellular swelling
Examples of Isotonic Fluids
Normal Saline
Ringer’s solution
Lactated Ringers
What does Ringer’s solution contain?
Sodium
Potassium
Calcium
What is missing from Ringer’s solution?
Dextrose Magnesium Bicarbonate Calories Free water
What does Lactated Ringer’s contain?
Sodium Potassium Calcium Chloride Lactate
What is missing from Lactated Ringer’s
Dextrose
Magnesium
Free water
What is hypotonic solutions used for?
Prevent & treat cellular dehydration by providing free water to the cells
Contraindications to Hypotonic Solutions
Acute brain injuries
Why are hypotonic solutions contraindicated in acute brain injuries?
Cerebral cells are very sensitive to free water, absorbing it rapidly & leading to cerebral cellular edema
Examples of Hypotonic Fluids
5% dextrose in water (D5W)
1/2 NS
1/4 NS
D5W & the Body
Dextrose metabolized
Free water shifts from vessels to cells
1/2 NS & 1/4 NS & the Body
Provide free water to cell as well as small amounts of sodium & chloride
Frequently used as maintenance therapy
Adverse Effects of Normal Saline (NS)
Fluid overload
Metabolic acidosis
Hypernatremia
Adverse Effects of Lactated Ringer’s
Fluid overload
Hyponatremia
Hyperkalemia
Adverse Effect of D5W
Hyponatremia
Clinical Types of Volume Deficit
Total body water
Extracellular
Intracellular
Total Body Water Volume Deficit
Water loss
Ex: diabetes insipidus, osmotic diarrhea
Extracellular Volume Deficit
Salt & water loss
GI tract losses
Third spacing
Examples of Salt & Water Loss in Extracellular Volume Deficit
Secretory diarrhea
Ascites
Edema
Examples of GI Tract Losses
Vomiting
Diarrhea
NG Sx
Enteric fistulas
Intravascular Volume Deficit
Acute hemorrhage
Define “Third Space”
Acute sequestration in a body compartment that is not in equilibrium with ECF
Causes of Third Spacing
Intestinal obstruction Severe pancreatitis Peritonitis Major venous obstruction Capillary leak syndrome Sepsis
Clinical Parameters to Help Judge Degree of Volume Loss
Weight loss BP JVP Urine sodium concentration Urine output HCT
States of Increased Fluid Loss
Fever Burns Sepsis Gastric fistulas Surgical drains Other states of increased metabolic activity
Clinical Findings of Extracellular Fluid Depletion
Thirst Decreased urine output Weight loss Drowsiness to coma Decreased skin turgor Dry mucous membranes Sunken eyes Tachycardia Orthostatic hypotension progressing to hypotension
Lab Findings in Extracellular Fluid Depletion
Increased HCT
Elevated BUN/Creatinine
Elevated urine sodium
Urine specific gravity >1.020
Clinical Signs to Monitor in Extracellular Fluid Depletion
Hemodynamic parameters
Urine output
Daily weights
Daily labs: HCT, BMP
Signs of HypOvolemia
Orthostatic hypotension Tachycardia Flat neck veins Decreased skin turgor Dry mucosa Supine hypotension Oligouria Organ failure
Signs of HypERvolemia
Hypertension Tachycardia Increased JVP Gallop Edema Pleural effusion Pulmonary edema Ascites Organ failure
Management of Hypovolemic Shock
1-2 L of isotonic solution on rapid infusion
Continue until clinical signs begins to improve
Type of Replacement Fluid in Hypovolemic Shock
Blood up to a HCT of 35%
Then crystalloid vs. colloid (need more crystalloid than colloid)
Advantages of Albumin over an Isotonic Saline
More rapid volume expansion
Lesser risk of pulmonary edema due to dilutional hypoalbuminemia
Disadvantages of Albumin over an Isotonic Solution
Cost
Not as readily available
Why not hyperoncotic starches in treatment of hypovolemia?
Increased risk of acute kidney injury
Increased mmortality
What should be given if a patient becomes acidotic on isotonic saline for the treatment of hypovolemia?
Add sodium bicarbonate to the infusate
Treatment of Mild to Moderate Hypovolemia
Administer isotonic solution at a rate greater than the rate of continued fluid losses
Continued Fluid Loss is the Sum of
Urine output
Insensible losses
Other fluid losses (GI)
How much more fluid than fluid losses should be administered?
50-100 mL/hour
What type of fluid should be used in hypernatremia?
Hypotonic solutions
What type of fluids should be used in hyponatremia?
Isotonic solutions
Hypertonic solutions
What type of fluid should be used in blood loss?
Isotonic solution
Blood products
When would potassium or bicarbonate need to be added to the fluids?
Hypokalemia
Metabolic acidosis
What are disorders of sodium regulated by?
Thirst
ADH
Renal water handling
What is hypernatremia usually due to?
Water loss
Management of Hypernatremia
Correct slowly: 10 mEq/L
IVF: hypotonic
Rate of infusion calculated using the Midas Formula
Things to Consider When Determining how Much Fluid to Give
What is your starting point?
Expected losses?
Expected gains?
What are expected losses?
Measureable: urine, GI
Insensible: sweat, exhaled, fever
Fever: increase by 100 mL/day/degree centigrade
Who needs maintenance therapy?
Unable to eat or drink for a prolonged period of time
Preoperative period
Ventilated patients
Goal of Maintenance Therapy
Maintain fluid & electrolyte balance
Provide good “nutrition”
Monitoring for Maintenance Therapy
Baseline serum sodium
Baseline weight
Daily electrolytes
