HUNG 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