Perioperative Fluid therapy Flashcards
% tbw in the average adult
60% water
Low % of water in _______ tissue
adipose
intracellular fluid compartment %
55%
Extracellular fluid compartment %
25%
Extraceulllar componenets
Interstitial: lymphatics and protein-poor fluid around cells
Intravascular: plasma volume
Transcellular: GI tract, urine, csf, joint fluid, aqueous humor
Describe diffusion (5)
-Solute particles fill solvent volume
-High to low concentration
-Speed is proportional to distance squared
-Can occur across permeable membranes
-Can relate to electrical gradients
types of solutes
Glucose, proteins, electrolytes
Primary extracellular cation
Sodium
Primary intracellular cation
Potassium
Describe osmosis
A semipermeable membrane separates pure water from water with solute
Diffuses from low to high concentration
Osmotic pressure formula
P = nRT/ V
N = number of molecules
R= constant
T= Temperature
V= Volume
Osmotic pressure definition
Pressure that resists the movement of water through osmosis
number of osmotically active particles/L of solvent
Osmolarity
_____osmolarity…_____“pulling power”
Higher osmolarity…higher “pulling power”
Number of osmotically active particles per kg of solvent
Osmolality
normal osmolality
Normal: 280-290 mOsm
The component of total osmotic pressure due to colloids
Oncotic pressure
Colloids types
Albumin (most), globulins, fibrinogen
Albumin % responsible for oncotic pressure
65-75% from albumin
Average intake (3)
750 ml of solids
350 ml from metabolism
1400 ml liquid intake
Average ouptuts (3)
1000 ml insensible loss (tears/vapor)
100 ml GI loss
0.5-1 ml/kg/hr urine output (60%)
ADH response
Antidiuretic Hormone (ADH) – renal H2O excretion in response to plasma tonicity.
ANP response
Atrial Natriuretic Peptide (ANP) – activated with ↑ fluid volume
↑ atrial stretch = ↑ renal excretion.
Aldosterone response
Aldosterone – regulates Na+ and K+ levels
If Na+ and fluid volume ↓ aldosterone is released causing Na+ and H2O conservation.
Urine output is regulated by
adh
ANp
aldosterone
Urine section = ____ of dailty water loss
60%
Sensory for fluid balance (3)
Hypothalamic osmoreceptors
Low pressure baroreceptors; large veins and RA
High pressure baroreceptors; carotid sinus and aortic arch
Triggers for fluid balance
Increased thirst or adh release
The compensatory mechanism for disturbances in circulating volume (5)
Venoconstriction
Mobilization of venous reservoir
Autotransfusion from ISF to plasma
Reduced urine production
Maintenance of CO…tachycardia, increased inotropy
Sensors for disturbances in circulating volume
low and high pressure baroreceptors
RAA axis
RAA axis
Renin
ang 1 becomes 2
aldosterone released from adrenal cortex
Renin facts
Released from juxtaglomerular cells
Cleaves angiotensinogen to make angiotensin I
Angiotensin I becomes II causes
vasoconstriction and aldosterone release
Aldosterone released from adrenal cortex causes_____
salt and water retention
IN the absence of ongoing loss RAA axis and compensatory mechanisms restores ______
Restores volume in 12-72 hours
Restores RBC numbers through erythropoiesis in 4-8 weeks
NS na, cl, osmolarity
na; 154
cl; 154
osmolarity; 308
LR; na, k , cl , lactate, osmolarity
na; 130
k; 4
cl; 109
lactate; 28
osmolarity; 274
Isolyte P; na, k, cl, mg, acetate, glucose, posphate
na; 26
k; 21
cl; 21
mg; 3
acetate; 24
glucose; 5
phosphate; 3
Plasmalyte A; na, k, cl, acetate, osmolarity
na; 140
k; 5
cl; 98
acetate; 27
osmolarity 295
D5 glucose and osmolarity
gluose; 5
osmolarity; 252
Albumin 5% na; k, cl, osmolairty
na; 145 + 15
k; <2.5
cl; 100
osmolarity 330
Hetastarch 6% na, cl , osmolairty
na 154
cl; 154
osmolarity; 310
Solutions of electrolytes in water
Crystalloids
Called balanced solutions
Crystalloids
Most balanced crystalloid
LR
indications for crystalloids
Replacement of free water and electrolytes
Volume expansion
Distribution of crystalloids volume through entire ecf
70% intravascular after 20 minutes
50% after 30 minutes
Too much crystalloids can cause____ and where?
Tissue edema
Lung, gut, soft tissues
Cyrtalloids side effect
Hypercoagulable…anticoagulant factors diluted (at low dilution)
effects of ns (0.9%) (3)
-Dilutes hct and albumin
-Increases cl- and K+ concentrations
-Late onset of diuresis
Side effect of NS (2)
Causes hyperchloremic metabolic acidosis
Increased AKI and RRT in critical care patients
Pulls water out of ICF to ECF including plasma
Hypertonic saline (3%)
Hypertonic saline used for _____
Treats hypoosmolar hyponatremia
Treats increased ICP
Much lower osmolarity than NS
LR; Lower Na+ and Cl- concentrations (close to plasma)
Lr has ___ added as a buffer
Lactate added as buffer
What relies on hepatic metabolism?
Lactate (dont use LR for liver insufficiency)
Lr Excretes excess water faster than ns
by____
Suppresses adh secretion/allows diuresis
Indications for Dextrose solutions
A source of free water (5%)
Could be used for caloric intake in diabetics (10%)
Dextrose is not suitable for _____
Not suitable for volume expansion; water moves freely between all compartments
Large molecules of a homogeneous, non-crystalline substance that cant be separated
Colloids
Types of colloids
Semisynthetic colloids; hetastarch, hespan
Human plasma derivatives; FFP
Colloids dispersion facts
Large molecules of a homogeneous, non-crystalline substance (in a balanced solutions (crystalloid).
Cant be separated. Disolved in crystalloid
dispersed in a second substance (typically a balanced crystalloid)
Particles cannot be separated (through filtration or centrifuge
effects of colloids
Increased cop = increased potential plasma volume expansion
Cause hemodilution
Uncertain effect on immune, coag, renal systems
What are the effects of colloids causing hemodilution (2)
Decrease plasma viscosity
Inhibit rbc aggregation
when are Uncertain effect on immune, coag, renal systems of colloids seen?
Maximum recommended dosages
Hydroxyethly starch is Modified natural polymers of ____
Modified natural polymers of amylopectin
where is hydroxethyl starch deterived from
Modified natural polymers of amylopectin
Derived from potato or maize
Substitution onto glucose
Hydroxyethyl starch metabolism is dependent on_____
Metabolism dependent on molecular weight of molecules
Hydroxyethyl starch effects
Plasma volume effects last longer
70-80% larger at 90 minutes
side effects of Hydroxyethyl starch
Side effects r/t MW
Coagulopathy…vwf, factor VIII and clot strength (at high dilution)
Renal dysfunction
Highly branched polysaccharides
Dextrans
Dextrans highly branched polysaccharides are procduced by _____
Produced by leuconostoc mesenteroides
Dextrans plasma volume is similar to______
Plasma volume similar to the starches (6-12 hours)
When is dextrans used and what are the effects
Dextran-40 used for microvascular surgery
Inhibits factor VIII, vWf factor, platelet aggregation
Coats rbc…may interfere with cross-matching
Types of human plasma derivatives
Albumin 5%, FFP, immunoglobulin solution
Physiologic COP with plasma derivatives indications_____ (4)
Volume replacement
Trauma, sepsis, replacement following paracentesis
indications for preop fluids (9)
Disordered Na+ distribution
Requirement for dialysis
Chronic use of diuretics
Diagnosis of hypertension
Preop fasting
Bowel prep
Acute hemorrhage
N,V,D and/or suction
3rd space redistribution
indications for intraop fluids (6)
Vasodilation from anesthetics
Sympathetic blockade
Autoregulatory responses
Acute hemorrhage
Insensible losses
Inflammation related redistribution
Assessments of low intravascular volume (5)
-Signs of hypovolemia; Tachycardia, ↓ pulse pressure, hypotension, ↓ capillary refill
-urine output; Inadequate as end-organ due to raa
-CVP; Measures central venous volume but distensible
-Tissue perfusion; lactate, mixed venous O2
Assessments of high intravascular volume (5)
Excessive crystalloids/colloids;
-↑ capillary hydrostatic pressure
-Excessive fluid development in lungs, bowel, muscle
-Reduced tissue oxygenation
-Poor wound healing
-Hypo/hyper coagulation
Uses for classic fluid therapy
NPO deficit
ongoing maintenance
anticipated surgical loss
Npo status
Clear liquids: 2 hours
Breast milk: 4 hours
Infant formula: 6 hours
Light meal: 6 hours
Meat/fatty, fried: 8 hours
classic approach for NPO/ maintainance formula (4-2-1)
1st 10 kg = 4ml/kg/hr
2nd 10kg = 2 ml/kg/hr
Each 1kg > 20kg = 1 ml/kg/ hr
calculate total deficit
(multiply by number of hours of NPO)
How to replace a NPO deficit
½ in the 1st hour of surgery.
¼ in the 2nd hour.
¼ in the 3rd hour.
Estimating Blood loss possiblities
Suction
Lap sponges 100ml
Raytech’s 20ml
4x4’s 10ml
Lap sponges thats saturated holds
100 ml
come in packs of 5
Raytechs comes in packages of ____
10
why do sponges have markings?
x ray able
Hypovolemic replacement
Preoperative bleeding
Crystalloid traditionally 3:1
May replace prbc’s, ffp, cryo using TEG/ROTEM
Average fluid with bowel prep
2000ml average
Everage fluid loss with fever
10% deficit q1degree Celsius
evaporative/redistribution losses
Minimal= 0-2 ml/kg/hr
Moderate = 2-4 ml/kg/hr
Severe = 4-8 ml/kg/hr
Parkland Burn resuscitation formula; what to use, when to use, and how much to give
Based on “rule of 9’s”
Adjusted due to obesity
Lactated ringers
use formula if; 20% TBSA of 2nd/3rd degree burns
4ml/kg/%BSA burn
½ over 1st 8 hours
½ over next 16 hours
Rule of 9s
Head; 9
chest ; 9
abdomen; 9
upper back; 9
lower back; 9
legs; 9 and 9
arms together; 4.5 and 4.5
perineum; 1%
Goal directed therapy fluid administration is based on_____
Cvp
Co
sv
Svv
What do the studies show about goal directed therapy
Studies: less aki, respiratory failure, wound infection, mortality
Goal-directed therapy allows decisions to use:
More fluid
Vasopressors
Inotropes
Blood products
Goal-directed therapy principles (3)
-Maintenance of 1-3 ml/kg/hr of crystalloid
-Fluid challenges of 250cc to increase sv
-Colloids 1:1 with blood loss or blood products
Normal svv
10-15%
Shows difference in arterial pulse pressure during inspiration/expiration
(SPV, PPV, SVV)
Limits to arterial waveform pressure monitoring
SVV >15% = fluid responsive
Low hr/rr
Irregular heartbeats
Mechanical ventilation (with low tidal volume)
Increased abdominal pressure
Thorax open
Spontaneous breathing
