Fluid Therapy Flashcards
What percent of body weight is water
60%
Pediatric: maybe 70%
Obese: use lean body weight for calculations (lean body weight is 70% of BW)
In dogs and cats, what percent of total body water is intracellular vs extracellular
Intracellular: 2/3 of TBW (40% BW)
Extracellular water: 1/3 of TBW (20% BW)
within this, interstitial water is 75% of ECF and intravascular water is 25% of ECF
Extracellular water is approx 1/3 of total body water (or 20% of body weight), what are its further subdivisions
Interstitial water: 75% of ECF
Intravascular water: 25% of ECF
2/3 of the total body water is _____________ (40% of body weight)
intracellular fluid
1/3 of the total body water is ____________ (20% of body weight)
extracellular fluid
If you have a 10kg dog. What is:
-TBW
-Intracellular fluid water
-Extracellular fluid water
-Interstitial Fluid Water
-Intravascular fluid
TBW: 0.6 x 10= 6kg
Intracellular: 2/3 of 6 L= 4L
Extracellular: 1/3 of 6L = 2L
Interstitial: 3/4 of ECF= 1.5L
Intravascular= 1/4 of ECF = 0.5L (1/12 of TBW)
About what percent of the body weight is blood volume
8-9% of BW in dogs
5-6% of BW in cats
Intravascular fluid water volume is about 5% of the body weight, why is the blood volume 8-9% of TBW and 5-6% of the body weight in cats?
Because blood contains both a liquid phase (plasma) and a cellular phase (RBC)
-IV water volume takes only the liquid phase into acocunt
If you have a 30kg dog. What is:
-TBW
-Intracellular fluid water
-Extracellular fluid water
-Interstitial Fluid Water
-Intravascular fluid
TBW= 0.6xBW= 18L
ICF: 0.67xTBW= 12L
ECF: 0.33xTBW= 6L
Intravenous Water (plasma) volume= 0.25xECF = 0.25x 6= 1.5L
Interstitial fluid volume= 0.75xECF= 0.75x6=4.5L
If you have a 5kg cat. What is:
-TBW
-Intracellular fluid water
-Extracellular fluid water
-Interstitial Fluid Water
-Intravascular fluid
TBW= 0.6xBW= 3L
ICF: 0.67xTBW= 2L
ECF: 0.33xTBW= 1L
Intravenous Water (plasma) volume= 0.25xECF = 0.25x 1= 0.250L
Interstitial fluid volume= 0.75xECF= 0.75x1=0.750L
Barrier between ICF and ECF compartments
Semi-permeable cell membrane
Freely permeable to water based on concentration gradients
Impermeable to electrolytes and proteins unless by transport
*Fluid move because of osmotic forces
How is fluid moved between ICF and ECF
Fluid move because of osmotic forces
Semi-permeable cell membrane
Freely permeable to water based on concentration gradients
Impermeable to electrolytes and proteins unless by transport
How is fluid moved within the ECF- between Int and IV
*Fluid moved because of Starling forces
-Endothelium
-freely permeable to electrolytes based on concentration gradients- water will follow
-relatively impermeable to proteins, larger molecules
Osmolality is proportional to
the number of non dissociable ions in a given solution
-not a function of the size or the molecular weight of the ion, just the number
expressed as mOsm/kg
How do you calculate osmolarity
2(NA +K) + BUN (mg/dL)/2.8 + Glucose (mg/dL)/18
Normal values are 280-305mOsm/L for dogs and 95-320 mOsm/L for cats
Is potassium higher ICF or ECF
ICF
Is Na+ higher ICF or ECF
ECF
Is Mg2++ higher ICF or ECF
ICF
Is Cl- higher ICF or ECF
ECF
What allows for movement of K+ out of cell and Na+ into the cell
Na/K ATPase
Effective osmoles
generate osmotic pressure across a semi-permeable membrane that is not permeable to that particle
*will result in movement of water
*Determines the tonicity of that compartment
ex: Sodium, Potassium
Why does albumin have minimal effect on osmolality
because its molecular weight is very high (66,000 Da) which makes the particle number relatively low
*We use colloid osmotic pressure, also known as oncotic pressure, refers to the osmolality due to proteins
Ineffective osmoles
have osmotic potential but they are unable to diffuse across the barrier
No osmotic pressure is generated, no movement of water
contributes to total osmolality but not tonicity
ex: Urea (diffusible), glucose (metabolized)
Note: D5W is iso-osmolar AND hypotonic
What are Starling’s forces
determine the movement of water between the interstitial fluid compartment and the intravascular fluid compartment, within the ECF
1) Oncotic pressure
2) Hydrostatic pressure
3) Vascular permeability
4) Lymphatic drainage
The movement of fluid within the ECF depends on
1) Oncotic pressure
2) Hydrostatic pressure
3) Vascular permeability
(Starling forces)
What does hydrostatic pressure fluid movement depend on
The pressure difference between the capillary and the interstitial
causes fluid leakage out of the vessel
Capillary Hydrostatic pressure: primarily the venous pressure (Arterial pressure is not translated across the precapillary sphincter)
venous stasis will increase the capillary pressure
Intersitium hydrostatic pressure: characteristic of the tissue, tightness of the interstitial matrix
Venous stasis will ______________ the capillary pressure
increase
Changes in hydrostatic pressure causes
fluid leakage out of the vessel
What does oncotic pressure fluid movement depend on
the oncotic pressure difference between the capillaries and interstitisal
*Causes fluid to go into the vessels (Keeps fluids into the vessels)
Oncotic pressure depends on
proteins- number of particles = concentration/molecular weight
Differences in oncotic pressure causes fluid to ____________
go into the vessels
What is the normal capillary oncotic pressure
Dog: 21-25 mmHg
Cat: 23-28 mmHg
What does the filtration coefficient (Kfc) depend on
1) Capillary surface area: larger surface area will increase Kfc
2) Hydraulic conductivity (leakiness of the vessels)- characteristics of endothelium and endothelial continuity
*Liver and kidney have leaky vessels: large net movement of fluid out of blood vessels
*Brain and muscle have relatively tight vessels
What is the reflection coefficient
relatively permeability of the capillary bed to protein (reflection = bouncing back of the protein)
depends on tissue (low in liver, high in kidney)
Lungs have low Kfc and high reflection coefficient (non leaky)
Lungs have low Kfc and high reflection coefficient. What does that mean
they are relatively non-leaky
Changes in osmolality moves water between
ECF and ICF
glycocalynx
dense, gel-like meshwork that surrounds the cell, constituting a physical barrier for any object to enter the cell
difference in the oncotic pressures on each sides is what drives the movement of fluids
What are the different kinds of crystalloids
1) Hypotonic :D5W, 0.45% NaCl
2) Isotonic: LRS, 0.9% NaCl
3) Hypertonic (7.2% NaCl)
What are the different kinds of colloids
1) Synthetic (Hetastarch, Vetstarch)
2) Natural (e.g Plasma)
What are the different kinds of blood products
1) Fresh Whole Blood
2) Packed Red Blood Cells
3) Plasma Products
4) Platelet Products
Fluid shifts between the intersititium and IV compartments because of
Starling’s forces
1) Oncotic pressure
2) Hydrostatic pressure
3) Vascular permeability
4) Lymphatic drainage
What is the osmolality of hypotonic crystalloids
0.45% NaCl = 154 mOsm/L
What is the osmolality of isotonic crystalloids
0.9% NaCl = 310 mOsm/L
What is the osmolality of hypertonic crystalloids
7.5% NaCl = 1300 mOsm/L
Crystalloids can be classified on osmolality but how else can they be divided?
Based on electrolyte composition and acid base effects
-NaCl based vs balanced electrolyte (LRS or Plasmalyte)
-The amount and type of bicarbonate precursors
ex: 0.9% NaCl has none and is therefore an acidifying solution
ex: LactaTe (LRS) or lguconate/acetate (Plasmalyte) are alkalinizing solutions
What are examples of alkalizing solutions
LRS (Lactate is the bicarb precursor)
Plasmalyte/ Normosol R both have Acetate gluconate as their bicarb precursors
What is D5W
it behaves like water
No electrolytes or bicarb precursors
same osm of water (~287)
What do hypotonic crystalloids behave
it is distributed in both the ICF and ECF compartments
volume of distribution depends on the amount of Na in the solution
sometimes easier to consider hypotonic cyrstalloids as isontonic + water
-Isotonic fluid distribute 100% in ECF compartment
Water distributes 67% ICF and 33% ECF
How does isotonic fluid distribute when given
100% in the ECF compartment
You have 1000mL of Dextrose 5% in water. How is it distributed
D5W is iso-isomolar and hypotonic solution as dextrose is not an effective osmole (metabolized readilyy)
Should be consider equal to 1000mL of free water
so
ICF: 67% of 1000mL = 670mL
ECF: 33% of 1000mL = 330mL
You have 1000mL of 0.45% NaCl. How is it distributed?
is equal to 500mL of water + 500mL 0.9% NaCl
so
ECF distribution= 500mL + 33% of 500= 500+ 165= 665mL
ICF distribution= 67% of 500mL= 335mL
When should you use hypotonic crystalloids
1) True “maintenance” fluids
2) Free water deficit (ie. hypernatremia)
3) Maintenance fluid when Na restricted is needed (e.g heart and renal disease)
When are hypotonic crystalloids indicated
1) IV compartment volume expansion (ie shock treatment) - not good at going to the vasculature
2) Free water gain (hyponatremia)
What are the side effects of giving hypotonic crystalloids
1) Hyponatremia
2) If administered rapidly causes acute changes in blood osmolarity and fluid shifts
3) Resulting in neurological sequels and RBC damage
What are the most commonly used IV solutions
Isotonic crystalloids
-LRS
-Plasmayte 148, Plasmalyte A, Normosol R
-Normal/physiologic saline (0.9% NaCl)
What is the fluid behavior of isotonic crystalloids
*Stays within the ECF (3/4 intersititium space, 1/4 in intravascular space)
*Doesnt go into ICF
Redistribution to interstitial within 20-30 minutes according to Starling’s forces
T/F: isotonic crystalloids do not go into the ICF
true
*Stays within the ECF (3/4 intersititium space, 1/4 in intravascular space)
What are the indications for using Isotonic crystalloids
1) IV volume expansion (ie. treatment of shock)
2) ECF volume expansion (ie. rehydration, treatment of dehydration)
3) Replacement of ongoing loses
What are the contra-indications to using isotonic crystalloids
1) Low oncotic pressure
2) Severe cardiac or renal disease
3) Severe, active bleeding (large volume contraindicated)
4) Free water loss or gain (sodium disturbances)
What are the side effects of giving isotonic crystalloids
-Possible tissue edema (if aggressive/large volume) bc it goes into interstitial
-Possible worsening or creation of acid-base disorders
-Pro-inflammatory effects
How do hypertonic crystalloids behave
causes a shift of fluid from ICF/interstitium into the IV compartment
*Rapid volume expansion (5-7x the volume given)
But rapidly redistribute across all compartments (10-30min) - only transient impact on IV volume expansion
Also have microcirculation effects and improved cardiac contractility
horses: give smaller volumes
What are the indications for using hypertonic crystalloids
1) IV volume resuscitation (ie. shock treatment)
2) Traumatic brain injury- sucks water out of the brain
3) Correction of acute hyponatremia (usually use 3% NaCl)
What are the contra-indications for using hypertonic crystalloids
1) Chronic hyponatremia
2) Severe dehydration
What are the side effects of hypertonic crystalloids
1) Only transient volume expansion for 20-30 min
2) Cannot be re-dosed
3) Causes transient hypernatremia
4) Reflect vasodilation and bradycardia if bolused too fast
How do colloids behave
they contain larger molecules which do not readily cross capillary membranes
volume stays in the vascular space
contribute to oncotic pressure
How does hydroxyethyl starch (HES) behave
it is a synthetic colloid, modified polymers of amylopectin
volume of distribution is vascular space
volume expansion power of 80-120%
prolonged vascular expansion time compared to crystalloids
When should you give synthetic colloids like (HES, VES, Dextrans, Gelatin, HBOC)
1) IV fluid resuscitation (ie shock)- especially in cases with low albumin or transient response to isotonic crystalloids
2) Oncotic support for hypoproteinemia
What are the side effects or contraindications behind using synthetic colloids like (HES, VES, Dextrans, Gelatin, HBOC)
1) Coagulopathy: dose dependent (more than 20ml/kg/day with HES) but lower MW colloids like VetStarch is less concerning
mostly due to impaired platelet function
2) Renal injury: concern for increased risk of AKI and kidney failure in critically ill patients (lack of evidence in pets , just humans)
How might synthetic colloids like (HES, VES, Dextrans, Gelatin, HBOC) cause coagulopathies
mostly due to impaired platelet function
*VetStarch is less concerning than HES
What is the fluid behavior when giving natural colloids (plasma)
usually thought to expand vascular volume equivalent to the amount given (100%)
What are the indications for using natural colloids, like plasma
1) Acute blood loss
2) Coagulopathy
3) Hypoalbuminemia
What are the adverse effects of natural colloids
1) Cost
2) Low Availability
3) Transfusion reactions (less than 1%)
What is the fluid behavior of human serum albumin
stays in the vasculature AND pulls fluids from intersitium and ICF (VEP >100%)
What are the side effects of Human Serum Albumin
1) Acute (type I) and delayed (type III) hypersensitivity
2)redosing is absolutely contra-indicated and will trigger anaphylactic shock
3) In people, no documented benefit, except maybe in septic shock
What are the indications for human serum albumin
There really arent, it is a strong debate but possible severe sepsis and septic shock (hypoalbuminemia with severe side effects)
most patients it is contra-indicated, if previously received HSA especially
What are the pros/ cons of the oral/enteral route
Pros:
Most natural way, low cost and risks, can also provide nutritional/calric support, either spontanteous drinking or through feeding tube, much less risk of volume overload
Cons: usually patients needed fluid therapy were not able to maintain volume status to begin with because of sickness, need functional GI tract, volume and speed of administration is usually too high for correction of dehydration and/or hypovolemia
What are the complications of the oral/ enteral route
low effeciveness for fluid expansion
Risk of aspiration pneumonia if vomitting and/or low LOC
What are the advantages of IV route
1) Direct vascular access for volume expansion
2) Rapid administration is possible- cut down placement if needed
3) Multiple types of fluid can be given (all types of cyrstalloids, colloids, blood products)
used for IV fluid resuscitation, significant dehydration (especially with expected ongoing losses), critically ill patients
What are the indications for using IV route for fluids
used for IV fluid resuscitation, significant dehydration (especially with expected ongoing losses), critically ill patients
What are the peripheral IV locations that you can use
Cephalic
Medial saphenous in dogs
Lateral saphenous in cats
What are the central IV locations that you can use
Usually on the jugular vein
usually longer and with multi-lumen
can be peripherally inserted central catheter (PICC) in the lateral or medial spahenous
What are the differences between administering peripheral vs central vein IV
Peripheral: fast, easy cheap and the bigger and shorter catheters allows for a faster administration because the flow of the fluid is proportional to the radius of the tube but only for relatively isotonic fluid and is easy to dislodge and cant be used for sampling
Central: Safer admin of hypo- and hypertonic fluids, serial blood sampling but requires more expertise and shouldnt be used for TBI or high risk bleeding patients
Can peripheral or central venous be used for serial sampling
Central venous
Can peripheral or central venous be used for isotonic solutions
peripheral venous
When might the intraosseus route be used
1) Smaller patients (ie neonates_
2) Exotics such as birds or others
3) rapid access if IV access is not possible or challenging (ie shick, CPR)
4) Various sites: proximal humerus, femur or tibia; birds: distal ulnar and proximal tibia
What are possible complications of IV catherization
1) Infection/Inflammation- thrombophlebitis or catheter side inflammation/ infection
2) Thrombosis/ thromboembolism- clot formation with potential migration
3) Extravasation of fluids from catheter can cause severe necrosis
4) Blood loss if disconnected
5) Blood stream related infection (BSRI)
6) Cathetic fragment foregin body
What are the pros and cons of the intraosseus route?
Pros: rapid access to vascular space when IV not possible or challenging, drugs and fluids can be given equivalent to IV, relatively easy placement
Cons: often short-lived access, complications are not uncommon- infection (osteomyelitis), fracture, maybe technically challenging in very small patients
How are SQ fluids absorbed
fluid is administered in the intersitium (between shoulder blades) and will be gradually absorbed and distributed across fluid compartments according to Starling’s forces
-speed of distribution dependent on hydration status and peripheral perfusion
What kinds of fluids can be given through the SQ route
Only administer isotonic fluids, usually LRS
-Hypo/hypertonic solutions (ie D5W) can cause significant irritation/ and otissue injury
*some isotonic fluids like Plasmalyte may sting and should be avoided
T/F: you can give hypotonic solutions through SQ route
False
Hypo/hypertonic solutions (ie D5W) can cause significant irritation/ and otissue injury
What are the indications to giving SQ fluids
1) Mild dehydration
2) patient cannot be hospitalized
What are the advantages to giving Sq fluids
1) inexpensive
2) easy technically
3) Can be administered by owners as needed
What are the disadvantages of giving SQ fluids
1) Unreliable absorption
2) Limited volume so not for severe dehydration
3) Slow absorption so not for shock
4) Limited options for fluid administered (only isotonic)
What is the dose of most SQ fluids
Dose dependent of the room between the shoulder blades as well as appropriate rehydration volume (eg 5% of body weight)
What are the complications of SQ fluids
pain, irriation
pressure necrosis
excessive admin
hematoma
infection: SQ cellulitis, abscess formation
When you are talking about dehydration, what are you talking about
Loss of isotonic fluid (aka ECF- loss of water AND salt)
Dehydration is loss of
ECF - water and salt
What are the 5 physical examination signs of dehydration
1) Mucous membranes
2) Skin elasticity (turgor)
3) Position of eye in orbit
4) Changes in body weight
5) Volume status
6) + Thirst mechanism
How can you examine dehydration in a patient
Physical signs
1) Mucous membranes
2) Skin elasticity (turgor)
3) Position of eye in orbit
4) Changes in body weight
5) Volume status
6) + Thirst mechanism (behavior change)
Bloodwork: PCV/TP and BUN, creatinine
Urinalysis: specific gravity
When do signs of hypovolemia due to dehydration become evident
When the patient is severely dehydrated (10-12%)
How does the eye position change in due to dehydration
Mild dehydration (5-7%): normal position
Moderate dehydration (8-10%): may be sunken
Severe dehydration (10-12%): sunken eyes
How does skin elasticity change due to dehydration
Mild dehydration (5-7%): slightly decrease
Moderate dehydration (8-10%): decrease
Severe dehydration (10-12%): stands in a fold
What do the mucous membranes look like when a patient is dehydrated?
tacky
T?F: dehydration decreases tear and saliva production
true
What influences membrane moistness
1) Hydration staus
2) Evaporation (panting)
3) Tear production influenced by KCS “dry eye”
How does the skin elasticity test determine hydration status
there is less fluid in the interstitial space and there is a decrease in elasticity/ turgor leading to an increased time to return to a normal position
Elasticity of the skin depends on
hydration status - also used to assess overhydration
also age
young: increase skin elasticity
old: decrease skin elasticity
obese: increase skin elasticity
How do young animals influence the skin elasticity test
they have increased skin elasticity
How do old animals influence the skin elasticity test
they have decreased skin elasticity
How do obese animal influence the skin elasticity test
they have increased skin elasticity
What other factors influence the position of the eye in the orbit for dehydration assessment
1) Obesity
2) Ocular disease
3) Breed and conformation
What causes the eye to sink with dehydration
sunken eye is associated with reduced volume of retrobulbar fat
What is the best way to assess hydration status
changes in body weight
get historical background
-normal dogs- no access to water
-induce dehydration (diuretics)
-monitoring body weight and physical examination findings
furosemide depletes a patients
extracellular fluid compartment
A patient that is 10% dehydrated lost
10% of their body weight
ex: 10 kg dog that is 10% dehydrated lost one L of water
What 2 factors triggers the thirst sensation
1) Decrease in ECF (aka dehydration) triggers ADH release which triggers RAAS system and triggers thirst centers in the brain to search out and ingest water
2) Increase in osmolality of the extracellular space (ie an increase in the concentration of sodium)
Dehydration is loss of ___________ fluid while hypovolemia is loss of ____________ fluid
interstitial; intravascular
What percent dehydration causes shock
> 10% dehydration you have significant hypovolemia
-Loss of intravascular fluid
What is the difference between dehydration and hypovolemia
ex: 10 kg dog is 10% dehydrated and losts 10% of BW= 1kg=1L
Dehydration is loss of ECF compartment 3.4 from intersitium= 750ml and 1/4 from IV = 250ml
10% dehydration in a 10kg dog corresponds to a loss of 250mL from the intravenous compartment
if 10kg dog, 800mL is blood volume so they lost 31% of blood volume. you see signs of hypovolemia for a loss of 30% of blood voluleme
A 10kg dog is 10% dehydrated. How much IV volume is lost
10 kg dog is 10% dehydrated and losts 10% of BW= 1kg=1L
Dehydration is loss of ECF compartment 3.4 from intersitium= 750ml and 1/4 from IV = 250ml
10% dehydration in a 10kg dog corresponds to a loss of 250mL from the intravenous compartment
You will see the clinical signs associated with hypovolemia when ______________
greater than 30% of blood volume is lost / >10% dehydrated
T/F: the body can compensate to maintain vascular volume but cannot do the same for interstitium volume
True
How does dehydration affect BUN
it will increase it
Dehydration is loss of ___________ fluid so you should replace with _____________
loss of isotonic fluid; replace with isotonic crystalloid
What is the time frame for correcting dehydration
4-24 hours
(average is 8-12 hours)
depends on: severity, speed of loss, compensatory, species, comorbidities (heart, lungs, kidneys), age, practicality, monitoring abilities
What is the equation for maintenance (dogs and cats)
Dogs:
132 x BW(kg) ^0.75 or
(*) 70 x BW(kg)^0.75
-preferred
Cats:
70x BW(kg)^0.75
Generally, what are the fluids rate for maintenance in dog and cat
40-60mL/kg/day
or
2-4mL/kg/hr or 1-2mL/kg/hr
Big dog or cat= lower end
small dog= higher end
or
30 x BW(kg) + 70(ml/day)
After fluid maintenance, you want to do fluid replacement, what should you use
Isotonic crystalloid
-too much Na and too little K
-add potassium to the fluid bag
-kidneys will handle the sodium load
hypotenoic crystalloid or true maintenance fluid- Plasmalyte 56 or Normosol-M when renal function is compromised or if in heart failure; for large animals
How should you account for abnormal ongoing losses (vomiting, diarrhea, burns, etc)
weight the losses or just do 1/2 maintenance for a lot of diarrhea or 1x maintenance for a lot of diarrhea
How do you monitor ongoing losses
Re-assess the patient by blocks of 4-12 hours
-PE
-BW
-Fluid balance (input versus output)
-Quantitative: urine output if urinary catheter or amounts of food/water eaten/drunk
-Qualitative: hypersalivation, diarrhea
You are presented with a 3yo M/C Labrador retriever who has had diarrhea for the past 3 days. He got into the garbage the day before. Still drinking water. No hematochezia or melena.
T=101.3
P=108
R=30, mm pink
slightly tacky, CRT= 2sec
BW: 40kh
Skin tent is very mildly prolonged and the eyes are in their normal position in orbit. What is the amount of dehydration? What should you give for maintenance
Mild to moderate dehydration 5-8% (pick 6%)
Deficit = 40 x 0.06= 2.4 kg(L) lost
Fluid type: Isontonic crystalloid (LRS)
timeframe:
6hr = 400ml/hr
10 hours= 240ml/hr
Maintenance= 70x40^0.075= 1113mL/ day= 46mL/hr
Total= 446mL/hr for 6 hours or 286mL/hr for 10 hours
Shock is defined as
inadequate cellular energy production due to critical decrease in DO2 compared to O2 consumption VO2 in tissues
O2 need»»» O2 delivery
inadequate cellular energy production due to critical decrease in DO2 compared to O2 consumption (VO2) in tissues
O2 need»»» O2 delivery
shock
What is produced as a result of anaerobic respiration
Lactate
What are the results when there is a decrease in O2 delivery, seen in patients with shock
1) Anaerobic metabolism
2) Increased lactate production and decreased ATP production
3) Cell dysfunction and failure (pump dysfunction of NA-K ATPase leading to intracellular edema, leakage of intracellular contents extracellularly and inability to regulate intracelular pH)
4) Multi-organ dysfuction (MODS)
What is the result of pump dysfunction of Na-K ATPase during shock?
pump dysfunction of NA-K ATPase leading to intracellular edema, leakage of intracellular contents extracellularly and inability to regulate intracellular pH)
What could limit the delivery of O2 to tissues in dogs and cats?
1) Respiratory: hypoxemic
2) Heart: cardiogenic (Decreases in SV or HR)
3) Vessels: Hypoxemic- (Hemoglobin, SaO2, PaO2), Hypovolemic, Distributive
4) Organs/Cells: Metabolic
due a decrease in circulating blood volume
severe dehydration >10-12%
can be from GI losses (Parvovirus), excessive diuresis (AKI) or burn
or
Blood loss from trauma
Hypovolemic shock
Why might a patient be in Hypovolemic shock
due a decrease in circulating blood volume
severe dehydration >10-12%
can be from GI losses (Parvovirus), excessive diuresis (AKI) or burn
or
Blood loss from trauma
Why might a patient be in cardiogenic shock
shock due to decreased forward flow from the heart
1) Congesitve heart failure (Mitral valve disease, dilated/ hypertrophic cardiomyoapthy)
2) Cardiac arrhythmias (ventricular tachycardia, atrial fibrillation, bradyarrhythmia)
3) Cardiac tamponade (Obstructive shock)
4) Drug overdose- beta blockers, calcium channel blockers
How might a patient be in distributive shock
due to marked decrease or increase in systemic vascular resistance or maldistribution of blood
inadequate blood flow to organs, due to vasodilation- sepsis or anaphylaxis
obstruction of blood flow coming to heart or leaving heart
-Gastric dilation volvulus (GDV)
-Pulmonary thrombo-embolism (PTE), saddle thrombus
-heartworm disease, pericardial effusion
What is the result of obstruction of blood flow due to gastric dilation volvulus (GDV), PTE, saddle thrombus, heartworm disease, pericardial effusion?
Distributive shock
-due to marked decrease of increase in systemic vascular resistance or maldistribution of blood from the obstruction of blood flow from/away heart
How does sepsis lead to shock
vasodilation leading to inadequate blood flow to the organs (Distributive shock)
How does anaphylaxis lead to shock
vasodilation leading to inadequate blood flow to the organs (Distributive shock)
What are the different types of shock
1) Hypovolemic (decrease circulating blood volume from loss or dehydration- GI, diuresis, or burn)
2) Cardiogenic (decreased forward flow from CHF, arrhythmias, tamponade or drugs)
3) Distributive: inadequate blood flow from increased or decreased vascular resistance (sepsis, anaphlyaxis, GDV, PTE, HWI, pericardial effusion)
4) Hypoxemic shock: due to decreased O2 content in arterial blood from severe pulmonary disease, anemia, dyshemoglobinemia (CO toxicity, methmoglobinemia)
5) Metabolic shock: due to decrease in cellular metabolic machinery, hypoglycemia, cyanide toxicity, cytopathic hypoxia of sepsis
How does GDV lead to obstructie shock
there is compression of great vessel that decreases venous return and preload
How does cardiac tamponade lead to obstructive shock
there is compression of the heart leading to reduced diastolic filling
How does tension pneumothorax lead to obstructive shock
there is compression of the heart leading to reduced diastolic filling
What are potential causes of hypoxemic shock
due to decreased O2 content in arterial blood (CaO2= 1.34 x Hb x SaO2) + 0.0031 x PaO2)
1) Severe pulmonary disease
2) Low Hb: anemia
3) Dyshemoglobinemia: CO toxicity, methmoglobinemia
What are the potential causes of metabolic shock
due to decrease in metabolic machinery
1) Hypoglycemia
2) Cyanide toxicity
3) Cytopathic hypoxia of sepsis
What are the compensatory mechanisms for patients with shock
Goal to return to normal circulating volume and normal pressure
1) Increased sympathetic activity (EP/ NE) leading to Vasoconstriction (Increase HR and contractility)
2) Renin-Angiotensin- Aldosterone system activation + ADH release, leading to vasoconstriction-H20 and Na+ retention
3) Mobilization of fluid from interstitial to the intravascular space
What is the point of vasoconstriction as compensatory for patients with shock
Vasoconstriction under SNS activation leads to increase HR and contractility
Vasoconstriction under RAAS activation leads to H20 and NA2+ retention
What is the heart rate of patients with shock
Cats: HR <160 and HR >220 bpm
Dogs: HR >160 for small breed and >100 bpm for large breed
What are the pulse quality changes you will see in patients with shock
1) Pulse deficit
2) Bounding pulse: severe anemia and sepsis
3) Weak/Absent: femoral / metatarsal pulse- hypotension
4) Asymmetrical pulse: saddle thrombus of cats
What might you see with the CRT in patients with shock/ poor perfusion
> 2sec: vasoconstriction
<1s: vasodilation = sepsis