E4- Perioperative Fluid Mgmt Flashcards
What percentage of total body weight is water?
Who has lower TBW %?
- 60%
- Elderly + Obese patients = lower percent of TBW
Elderly + Obese patients = lower percent of TBW
Pediatrics = HIGHER TBW
What are the two main compartments fluid compartments?
- ICF = 2/3 TBW
- ECF = 1/3 TBW
What are 3 different compartments of the ECF?
- Interstitial = lymphatics + protein-poor fluid around the cell.
- Intravascular = plasma volume
- Transcellular = GI Tract, Urine, CSF, Joint fluid, aqueous humor.
What is diffusion?
- Solute particles moving or filling solvent volume
- High to Low concentration
- Speed is proportional to the distance square
- Can occur across permeable membranes
- Can relate to electrical gradients
What are examples of the type of solutes that are in our body?
- Glucose
- Protein (Albumin)
- Electrolytes
What is the primary extracellular cation?
- Sodium (Na+)
What is the primary intracellular cation?
- Potassium (K+)
What is osmosis?
- Semipermeable membrane separates pure water from water with solute
- Osmosis is just movement of WATER
- Diffuses from low to high solute concentration
What is osmotic pressure?
- Pressure that resists the movement of water through osmosis
What is osmotic pressure affected by?
Formula?
- Directly related = temp + # molecules
- Indirectly related = Volume
- P = nRT/V
PV = nRT
What is osmolarity?
- Number of osmotically active particles per L of solvent
- Higher osmolarity = higher “pulling power”
Patient A has serum glucose of 600mg/dl
Patient B has serum glucose of 250mg/dl
Who has higher osmolarity?
- Patient A
What is osmolality?
- Number of osmotically active particles per Kg of solvent
What is normal osmolality?
- 280-290 mOsm
What is oncotic pressure?
- The component of total osmotic pressure due to colloids
List examples of colloids
- Albumin
- Globulins
- Fibrinogen
What percentage of oncotic pressure is due to albumin?
- 65-75%
What makes up our daily intake?
Normal Daily Balance
- Solids = 750 mL
- Liquids = 1400 mL
- Metabolism = 350 mL
What makes up our daily output?
Normal Daily Balance
- Insensible Loss = 1000 mL
- GI loss = 100 mL
- Urine output = 0.5-1 mL/kg/hr
Urine secretion accounts for ____-% of daily water loss.
- 60%
What 3 hormones regulate urine output?
- ADH
- ANP
- Aldosterone
How does ADH regulate urine output?
- Renal H2O excretion in response to plasma tonicity
How does ANP regulate urine output?
- ANP is activated by ↑ fluid volume
- ↑ Atrial Stretch = ↑ Renal Excretion
How does Aldosterone regulate urine output?
- Regulates Na + K levels
- Aldosterone is released if sodium + fluid volume decreases»_space; Na + H2O conservation
What are the 3 sensors for fluid balance?
Locations?
- Hypothalamic osmoreceptors
- Low-pressure baroreceptors = large veins and RA
- High-pressure baroreceptors = carotid sinus and aortic arch
What are 2 trigger for fluid balance?
- Increased thirst
- Increase ADH
What are the 5 compensatory mechanisms for acute disturbances in circulating volume?
When do they occur?
- Venoconstriction
- Mobilization of venous reservoir
- Autotransfusion from ISF to plasma
- Reduced urine production
- Maintenance of CO = tachycardia + inotropy
MINUTES TO HOURS
What are the 3 sensors to acute disturbances in circulating volume?
o LOW + high pressure baroreceptors
o RAA axis
primarily low
Where is Renin released?
What does Renin do to angiotensinogen?
- Released from juxtaglomerular cells
- Cleaves angiotensinogen to make angiotensin I
When ANG I → ANG II, what will this cause?
- Vasoconstriction and aldosterone release
Where is aldosterone released from?
What does it do?
- adrenal cortex
- causes salt and water retention
In the absence of ongoing fluid loss, loss volume should be restored within ______- hours (range).
- 12-72 hours
In the absence of ongoing fluid loss, RBC should be restored through ______________ in ______ weeks (range).
- erythropoeisis
- 4-8 weeks.
What are the Electrolytes and Osmolarity of Normal Saline (0.9%)?
Na = 154 mEq/L
K = 0
Chlorid = 154 mEq/L
Osmolarity = 308 mOsm/L
What are the 4 Electrolytes and Osmolarity of LR?
Na = 130 mEq/L
K = 4 mEq/L
Chloride = 109 mEq/L
Lactate = 28 mEq/L
Osmolarity = 274 mOsm/L
NOT LIVER PTS
What are the 4 Electrolytes and Osmolarity of Plasmalyte?
Na = 140 mEq/L
K = 5 mEq/L
Cl = 98 mEq/L
Acetate = 27 mEq/L
Osmolarity = 295 mOsm/L
What are the Electrolytes and Osmolarity of Albumin 5%?
Na+: 145 +/- 15 mEq/L
K+: <2.5 mEq/L
Cl-: 100 mEq/L
Osmolarity: 330 mOsm/L
What are the Electrolytes and Osmolarity of Hetastarch 6%?
Na+: 154 mEq/L
Cl-: 154 mEq/L
Osmolarity: 310 mOsm/L
What are crystalloids?
- Solutions of electrolytes in water
- The are called balanced solutions (not really though, misnomer)
- LR/plasmalyte = probably considered the most “balanced” crystalloid