Fluid/Shock/Trauma Flashcards
Define limited fluid volume resuscitation (LFVR).
The goal of LFVR is to restore the perfusion with the smallest amount of fluid volume and minimize the risk of exacerbating hemorrhage.
The target blood pressure for LFVR is MAP at 70 mmHg or SAP at 90 mmHg until definitive control of hemorrhage is achieved (e.g. sx).
Define hypotensive resuscitation.
The goal is to resuscitate the patient to the MAP no greater than 60 mmHg until the definitive control of hemorrhage is achieved.
Define shock.
Inadequate cellular energy production
True or False: Neonates and pediatrics have higher lactate concentrations.
True
What is the equation for DO2?
DO2 (ml/min) = CO (ml/min) x CaO2 (ml O2/dl) = (HR x SV) x [Hb x SaO2 x 1.34 + PaO2 x 0.003]
- 1.34 = Hufner constant for human hemoglobin oxygen binding capacity in mL/g
- Hb (g/L)
What is the equation for VO2?
VO2 = CO x [CaO2 - CvO2]
According to the review paper published by Walton et al about venous oxygenation, what are the VO2 for anterior and posterior vena cava? What factors contribute this difference?
Anterior: 75%
Posterior: 80%
High cerebral oxygen extraction and high renal non-nutrient blood flow
What is the normal mixed venous oxygen saturation
SvO2 = 75%, PvO2 = 40mmHg
Define oxygen extraction ratio.
Oxygen extraction ratio (O2ER) = VO2/DO2
What cause increased O2ER?
Increased tissue oxygen demand
Decrease oxygen delivery
What is normal oxygen extraction ratio in a healthy individual? What is the critical oxygen extraction ratio?
Normal: 0.2 - 0.3
Critical oxygen extraction ratio: 0.79
What is critical oxygen extraction?
It is the point where the critical oxygen extraction ratio is met and the falling of DO2 fails to meet with the VO2 need. (bad bad)
What is the normal difference between SvO2 and ScvO2?
ScvO2 is usually 2-5% lower than SvO2
What are the four principle determinants of venous oxygen saturation?
Cardiac output
Hemoglobin concentration
SaO2 (arterial oxygen saturation)
Tissue oxygen consumption
What are the normal SvO2 and ScvO2?
ScvO2 65-70%
SvO2 70-75%
How many percentage of isotonic crystalloid will still remain in the intravascular space after fluid resuscitation?
25% (after 30 minutes)
Besides volume expansion, what are other benefits of HTS?
Decreased endothelial swelling
Improved cardiac contractility
Decreased intracranial pressure
Modulate inflammation (immune-modulatory effect)
Mild peripheral vasodilation
Draw “Tree of Life”
What are the systemic and local factors controlling the systemic vascular resistance?
Local: NO, CO2, Histamine, prostacyclin, endothelin, thromboxan, thrombin
Systemic: SNS (short term change), vasopressin, angiotensin II (long term change)
For patients experiencing acute bleeding, how many percentage of total intravascular volume needs to decrease in order for patient to be hypotensive?
30%
To respond to hypotension, the body develops what two reflexes?
Baroreceptor reflexes
Chemoreceptor reflexes (detect the change of arterial oxygen tension, CO2 and pH)
What are the two types of baroreceptors and where do they locate?
High-pressure arterial receptors:
- aortic arc, carotid sinuses
- when BP decreases → nerve firing is decreased → signals to the vasomotor center in medulla is decreased → increased sympathetic outflow
Low-pressure volume receptors:
- atria, ventricle, pulmonary vasculatures
Does angiotensin II cause release of vasopressin?
Yes it does
Which one is a strong acid, lactate or lactic acid?
Lactic acid
True or False: The metabolic acidosis associated by lactate production is due to excessive lactate accumulation.
False
The metabolic acidosis is due to ATP depletion (and decreased H+ consumption) instead of lactate accumulation.
- When the ATP made by glycolysis is utilized, H+ is released into the cytosol. This proton would usually enter the mitochondrion and be used to maintain the proton gradient required for the electron transport chain and oxidative phosphorylation. When oxygen supplies are insufficient this cannot happen and H+ ions accumulate and are then transported out of the cell.
Under normal condition, which organs are the major lactate production organs?
Skeletal muscles (40-50%)
Erythrocytes
Skin
Brain
- Red blood cells, leukocytes (predominantly neutrophils), and platelets are responsible for 80, 13, and 7% of lactate production in blood, respectively. (From lactate review paper)
Under normal condition, which organs are the major lactate consumption organs?
Renal cortex
Liver
Myocardium
Normally can we detect lactate in the urine? Where is it absorbed in the nephrons?
No
Proximal renal tubule (threshold: 6 to 10 mmol/L)
What is the half-life for lactate?
30-60 min
What are the definitions of type A and type B hyperlactatemia?
Type A: evidence of tissue oxygen deficiency (absolute or relative)
Type B: no evidence of tissue oxygen deficiency
- B1: associated with underlying diseases
- B2: associated with drugs or toxins
- B3: congenital errors in metabolism
How is propylene glycol caused hyperlactatemia?
Propylene glycol is metabolized into L-lactate, R-lactate and pyruvate.
True or False: An animal with hyperlactatemia will also has metabolic acidosis.
False
If the mitochondria function is normal and H+ can be metabolized, patient may not have metabolic acidosis.
True or False: The POC lactate meter can measure both L-lactate and D-lactate.
False
Only L-lactate
- In healthy animal, D-lactate is only 1-5% of L-lactate
What are the characteristic of 5% dextrose solution (isotonic vs hypotonic; isoosmotic vs hypoosmotic)?
Isoosmotic (250 mOsm/L), hypotonic (dextrose is metabolized in the vessels)
What are the three main natural colloid particles? Which one is the main contributor to COP?
Albumin (main; 80%), globulin, fibrinogen
What is the minimal degree of dehydration that can be detected on PE?
5%
When we assess patient’s hydration status by checking the skin tent and MM moisture, what are we actually checking?
A) Interstitial hydration status
B) Intravascular hydration status
C) Intracellular hydration status
A) Interstitial hydration status
- Intracellular hydration status cannot be detected by PE
Why shouldn’t we give HTS at a fast rate (> 1ml/kg/min)?
It can cause hypotension by central vasomotor center inhibition or peripheral vasomotor effect (due to hyperosmolality)
How much intravascular volume will 4 ml/kg of 7.5% HTS expand?
12-16 ml/kg
Where are lactate, acetate and gluconate metabolized?
Lactate - liver
Acetate - skeletal muscle
Gluconate - most cells in the body
What are normal COP in dogs and cats?
Dogs: 15-26 mmHg
Cats: 18-33 mmHg
What characteristics of a colloid solution are associated with longer half-life?
Higher molecular weight
Higher degree of substitutions
Higher C2 : C6 ratio
** These characteristics also confers to more significant coagulopathic effect
On the package of VetStarch, you will see 130/0.4. What does that mean?
130 means average molecular weight is 130K Da
0.4 means 4 hydroxyethyl group substitutions per 10 glucose molecules
How are the synthetic colloids metabolized/eliminated?
- Reticuloendothelial system (e.g. liver, spleen, lymphatic system)
- Amylase in the blood can also metabolized hydroxyethyl starch
- Excreted via the kidneys
What is the body fluid composition?
What are the most abundant cation and anion in ICF? What about ECF?
ICF: potassium, phosphate
ECF: sodium, chloride and bicarb
Fill out the blank.
What is the Na concentration in 0.9% NaCl, LRS and Normosol-R, respectively?
0.9% NaCl: 154 mEq/L
LRS: 130 mEq/L
Normosol-R: 140 mEq/L
What is the buffer in 0.9% NaCl, LRS and Normosol-R, respectively?
0.9% NaCl: none
LRS: lactate
Normosol-R: acetate, gluconate
What is the K concentration in LRS and Normosol-R, respectively?
LRS: 4 mEq/L
Normosol-R: 5 mEq/L
What is the Cl concentration in 0.9% NaCl, LRS and Normosol-R, respectively?
0.9% NaCl: 154 mEq/L
LRS: 109 mEq/L
Normosol-R: 98 mEq/L
Which fluid contains Ca and which contains Mg?
LRS contains Ca 3mEq/L
Normosol-R contains Mg 3 mEq/L
What is the osmolality of 0.45% NaCl + 2.5% Dextrose?
280 mOsm/L
- 0.9% NaCl: 308 mOsm/L
- D5W: 250 mOsm/L
What is the equation for free water deficit?
Free water deficit (L) = [(Measured Na - Normal Na)/Normal Na] x body weight x 0.6
Is VetStarch made up of tetrastarch or hetastarch?
6% Tetrastarch (hydroxyethyl starch)
What is recommended CRI for VetStarch? What is the daily dose limit?
0.5 - 2 ml/kg/hr
20 - 40 ml/kg/day