-
Total body water
- 50-70% of total body weight
- Average M>F
- Lean muscle contains h20>adipose
- Deceases w/ age
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Body water purpose
- Transport nutrients, gases and waste in/out cells
- Eliminate wastes
- Regulate body temp
-
ICF
- Approx. 40% body weight
- High in K, Mg
- Low Na, Cl
-
ECF
- 20% tbw
- Low K,MG
- High Na Cl
-
ECF divisions
- Interstitial fluid
- Plasma
- Fluid of bone and connective tissue
- Transcellular fluid
-
-
Interstitial fluid
- ECF
- LOW PROTEIN LEVEL
- “Fluid that fills the cracks”
- Approximately 10.5L
- It is the link between the intracellular fluid and intravascular space
- Oxygen, nutrients, wastes and chemical messengers all pass through
- Has the same compositional characteristics of ECF
- Lymph
-
Intravascular
- HIGH PROTEIN CONTENT
- CONTAINS RED AND WHITE CELLS
- ONLY major fluid that exists as real collection all in 1 location
- Plasma
- High bulk flow
-
Bone and ct fluid
Mobilized very slowly
-
Transcellular fluid
- Body fluids formed from transport activities of cells
- w/in epithelial lined spaces
- csf, urine, aqueous humor
- joint fluid
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Goals of Fluid Therapy
- Replace volume losses
- Protect organs from hypoperfusion injuries
- Maintain osmolarity
- Maintain acid-base and electrolyte balance
-
Colloid Solutions
- Contain large molecules that do NOT pass through semipermeable membranes
- remain in the intravascular space
- expand the intravascular volume
- draw fluid in via their higher oncotic pressure
-
Crystalloid Solutions
- Contain small molecules that flow easily across semipermeable membranes
- allowing for transfer from the blood stream into the cells and body tissues
- Increases fluid in BOTH interstitial and intravascular space
- Approximately 25% remains in the intravascular space 1hr after administration
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Osmolality
describes the solute concentration in body fluid by particles per Kilogram (# mOsm/Kg)
-
Osmolarity
- describes the solute concentration in body fluid by particles per Liter (# mOsm/L)
- - Normal 270-300 mOsm/L or Kg
-
Isotonic
- when a fluid is fairly EQUIVALENT in particle concentration to normal plasma osmolarity
- (270-300 mOsm/L)
- Osmotic pressure is constant on both inside and outside of cells
- fluid in each compartment remains the same (No shift occurs)
- Fluid does not move into the intracellular space
- remains in the extracellular space (intravascular and interstitial)
- Examples: 0.9% Normal Saline (0.9 NS), Lactated Ringers (LR), Ringer’s and 5% Dextrose in Water (D5W)
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Hypotonic
when a fluid is LESS concentrated than normal plasma osmolarity(<270 mOsm/L)
-
Hypertonic
when a fluid is MORE concentrated than normal plasma osmolarity (>300 mOsm/L)
-
Normal Saline 0.9%
- - Basically salt water, it contains 154 mEq/L of Na and Cl; isotonic
- - Increases the volume of the extracellular space
- - FLUID OF CHOICE FOR RESUCSCITATION EFFORTS
- - ONLY fluid that can be administered with blood products in the same line
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NS when to GIVE
- very good for replacing fluid volume deficit from
- hemorrhage, severe vomiting or diarrhea,
- heavy drainage from GI suction/fistulas/ostomies,
- draining wounds, shock, mild hyponatremia,
- hypercalcemia and fluid challenge
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NS caution use
- in your fragile patients such as the elderly
- cardiac and renal disease as there is potential for volume overload
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Lactated Ringer’s (LR)
- The MOST physiologically adaptable fluid
- it’s electrolyte content is most closely related to the composition of the body’s blood plasma
- metabolized in the liver which converts the lactate to bicarb (Alkalizing solution)
-
Lactated ringer’s Contents
130 mEq/L Na, 109 mEq/L Cl, 4 mEq/L K, 3 mEq/L Ca
-
LR When to GIVE
- another first choice for fluid resuscitation,
- similar clinical situations as 0.9% NS
- also used pre/post op, metabolic acidosis
-
LR When to use CAUTIOUSLY
- patient’s with liver disease or renal disease
- HOLD if pH is >7.5
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Isotonic Fluids: Ringer’s
- - Similar in make up to LR however doesn’t have the lactate therefore it doesn’t have the same liver contraindications
- - Not an alkalizing agent, no pH restriction
-
5% Dextrose in Water (D5W)
- Basically sugar water, contains 170 calories/L and no electrolytes
- Isotonic or Hypotonic…
- Provides “Free Water”
- Expands BOTH intracellular and extracellular compartments at the same time
- Good for hypernatremia, most often used as a maintenance fluid
- Although it does supply some calories, it’s not enough for prolonged use
-
D5W NOT used
- treat fluid water deficit
- 1. dilutes plasma electrolyte concentration
- 2. it won’t stay in the intravascular space
-
D5W Contraindicated
- In early post op because the body’s reaction to the surgical stress may cause an increase in ADH
- In patients with known or suspected increased intracranial pressure (ICP) due to it’s hypotonic properties following metabolism
-
Free water
- unbound water molecules small enough to pass through membrane pores to the intracellular space
- provided by D5W and hypotonic fluids
-
Isotonic Fluids… Final thoughts
- Patients can quickly develop hypervolemia following rapid or over infusion of isotonic fluids.
- Be MINDFUL!!!
- Monitor – Vitals, PE , Labs, I&O’s
-
Hypotonic Fluids
- Lower concentration or tonicity of solutes
- Osmolarity <250 mOsm/L
- Infusion causes a DECREASE in serum osmolarity within the vascular space
- Fluid will shift from the intravascular space to BOTH the intracellular and interstitial compartments.
- “Cell Hydration”
- BE AWARE the fluid WILL shift which can deplete the fluid within the circulatory system, worsening hypotension and causing circulatory collapse
- Examples: 0.45% NS, 0.2% NS, 0.33% NS, 2.5% Dextrose in Water
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Hypotonic Fluids CONTINUED
- Provide free water, NaCl, and replace natural fluid loss
- Assist with maintaining daily body fluids and electrolytes
- Help Kidneys excrete excess fluids and electrolytes
- Usually used during conditions that cause intracellular dehydration (DKA, hyperosmolar hyperglycemic state)
- NEVER GIVE: patients at risk for increased ICP or to trauma or burn victims
-
Hypertonic Fluids
- Higher tonicity/solution concentration causing an unequal pressure gradient between the inside and outside of cells
- Draws fluid OUT of the intracellular space therefore increasing extracellular fluid volume
- “Volume Expanders” – increases BP
- Reduces interstitial and endothelial edema
- Osmolarity >375 mOsm/L
- Examples: 3% NS, 5% NS, D10W, D20W, D50W
-
Concentrated NS
- Moderate to severe Hyponatremia,
- patient’s with cerebral edema
-
D10W
provides free water and calories (340 calories/L)
-
D20W
acts as an osmotic diuretic
-
D50W
- highly concentrated sugar water
- given rapidly via IV bolus to treat severe hypoglycemia
-
Hypertonic Fluids Continued
- Maintain vigilance
- potential for causing intravascular volume overload and pulmonary edema.
- GO SLOW
- Prescription for their use should include:
- why administering, total volume to be infused, rate of infusion, stop time
- Also you can always add Dextrose to other solutions to get benefit of calories plus electrolytes, with addition the solution will be made slightly hypertonic
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Colloid Solutions
- Contain molecules too large to pass through semipermeable membranes
- Volume Expanders - they draw fluid from the interstitial space into the intravascular compartment
- Similar to hypertonic solutions
- require administration of LESS total volume
- their effects last LONGER compared to crystalloids
- Examples: Albumin, Dextran, Hetastarch
-
Colloid Solutions…. 5% Albumin
- Most commonly used colloid solution
- Contains plasma protein fractions obtained from human plasma
- Works to rapidly expand the plasma volume
- Expensive
- BLOOD product so has same protocols and risks with administration
-
25% albumin
this draws out 4x its volume from the interstitial fluid into the intravascular compartment in 15 min!
-
5% albumin When to GIVE
- Patient’s with hypoproteinemia/malnourished,
- patient’s who require intravascular volume expansion and cannot tolerate large infusions of crystalloids,
- shock, post surgery – especially ortho/reconstructive surgery
-
Synthetic Colloid Solutions
- Dextran
- Hetastarch/6% hespan
-
Dextran:
- 1. Available in saline or glucose preparations
- 2. Can INTERFERE with blood typing
-
Hetastarch/6% Hespan:
- 1. Contains some Na and Cl
- 2. LESS expensive than albumin
- 3. Effects last 24-36hrs
- Colloids: Last Tidbits
- Need an 18G IV to infuse
- Colloid solutions can interfere with platelet function, increasing bleeding times. Monitor patient’s coagulation indexes
- Monitor closely for intravascular volume overload
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Sensible fluid loss
loss that can be measured, loss from the GI and GU tract.
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Insensible fluid loss
cannot be measured, loss from skin and lungs
-
Clinical Assessment of Volume Status
- Most of your patient’s will present with some degree of dehydration
- Red Flags: vomiting, diarrhea, fever, anorexia, AMS and decreased urine output
- Tachycardia and Hypotension are LATE findings
- Lab values are usually not reliable indicators
-
Calculating Fluid Deficit
- calculated based on number of Hrs NPO
- Hrs NPO x (60 +weight in kg - 20) ml = Fluid deficit
-
Calculating Fluid Maintenance requirement for normal adults
- 60ml + (weight in kg -20) ml = Fluids/Hr
- OR
- 4-2-1 Rule
- 4ml/kg/hr for first 10kg
- 2ml/kg/hr for next 10kg
- 1ml/kg/hr therafter
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To estimate Daily Fluid requirement,
use the 100-50-20 Rule
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Calculating Fluid Requirements in the Obese Pt
- Calculate for their IDEAL body weight.
- Men: 106 + 6lbs for every inch over 60 in (5ft)
- Women: 100 + 5lbs for every inch over 60 in (5ft)
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End Points to Resuscitation
- UOP 30-50 ml/hr or 0.5/kg/hr
- CVP 8-12 mmHg
- MAP >65 mm Hg
- ScVO2 >70%
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Central line Indications
- Central venous monitoring
- Volume resuscitation
- Cardiac arrest
- Lack of peripheral access
- Infusion of concentrated solutions/vasopressors
- Chemotherapy,
- epinephrine, dopamine, norepinephrine, vasopressin
- Placement of transcutaneous pacemaker
- Hemodialysis
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Central line Relative Contraindications
- Anticoagulated/Bleeding disorderso
- Combative patients
- Distorted anatomy-US may help with this
- Cellulitis/Burns/Vasculitis at site
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Central line Complications
- Air embolus
- Arterial entry
- Hematoma & Blood clot
- Infection
- Dysrhythmias-can cause V tach with IJ placement
- Nerve injury
- Pneumothorax/Hemathorax
- Bowel or bladder perforation
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Diagnostic errors
- Delayed, wrong, missed entirely
- 1 in 10 wrong
- 40-80K deaths US yrly
- Leading cause of med malpractice
-
Diagnostic error causes
- Inaccurate assessment of hx and PE
- Wrong interpretation of dx test
- Overreliance on clinical axiom
- Cognitive biases
-
Anchoring bias
- Locking on to salient features in pts initial presentation
- Failing to adjust in light of later info
-
Availability bias
Judging things to be more likely if they readily come to mind
-
Confirmation bias
Looking for evidence to support dx rather than looking for evidence to rebut it
-
Diagnosis momentum
Allowing dx labe that has been attached to pt to gather steam ->wrongful exclusion
-
Overconfidence bias
Believing we know more than we do and acting on incomplete data
-
Premature closure
Accepting a diagnosis before it is fully verified
-
Search satisfying bias
Calling off the search once something is found
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I VINDICATE
- Idiopathinc/psych
- Vascular
- Infectious or inflammatory
- Neoplastic
- Degenerative
- Iatrogenci ( drug/toxin)
- Congenital
- Allergic/autoimmune
- Trauma
- Endocrine/metabolic
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