Laws, Principles, and Formulas Flashcards
Reynolds’s number (Nr)
Helps determine if you have turbulent flow
Nr = (velocity x Density x 2Radius) / Viscosity
If product > 2000, turbulent flow can be expected
Poiseuille Law
V = ∆Pπ r^4 / 8Ln
Describes flow of fluids (air or liquid) in a tube.
Variables it takes into account are:
-flow (Q)
-viscosity (n)
-pressure gradient across tube (P)
-Length (L)
-radius (R)
greater than 2000 = turbulent
Newtons Law 1
Law of inertia: object in motion stays in motion
Newtons Law 2
F = M x A
When a constant force acts on a massive body, it causes it to accelerate at a constant rate
Newtons law 3
Action-reaction law: For every action there is an equal and opposite reaction.
Pascals law
P change in enclosed fluid = transferred undiminished through entire fluid/walls
Hooke’s Law
TLDR: Describes elasticity.
The elastic body stretches equal units of length/volume for each unit of weight/force applied to it
Limit:
(until the elastic limit of the system is reached). Exceeding the limit results in permanent distortion of the spring.
Boyles law
P1V1 = P2V2
Relationship of variables: -INVERSE-
Pressure and volume of a gas system vary inversely if the temp. and amount of gas are constant.
Charles Law
V1/T1 = V2/T2
Relationship of variables: -DIRECT-
Temp and vol. of a gas system vary directly if the pressure and amount of gas are constant.
Gay-Lussac’s law
P1/T1 = P2/T2
Relationship of variables: -DIRECT-
pressure and temp of a gas system vary directly if the volume and amount of gas in the system are constant.
Venturi Principle
P drop by restriction can be reversed with gradual tube dilation no more than 15 degrees
Bernoulli principle
As forward pressure of fluid/gas increases, lateral Pressure decreases
Bohr effect
Increased CO2 in tissues decreases affinity between O2 and Hb.
TLDR: Dumps O2 at tissues
Haldane effect
The affinity of hemoglobin for CO2 is greater when it is not combined with 02.
TLDR:
Promotes the dissociation of CO2 from hemoglobin.
Henry’s law
Amount of dissolved gas in a liquid is proportional to the pressure of the gas around the liquid
Factors Affecting Hb Affinity for O2:
Increased Affinity (shift to left)
Decrease in:
-PCO2
-H+
-Temp.
-DPG
Increase in:
PH
Factors Affecting Hb Affinity for O2:
Decrease Affinity (shift to right)
Decrease in:
-PH
Increase in:
-PCO2
-H+
-Temp
-DPG
BMI Calculation
Wt (Kg) / Ht (m)
How do you find O2 content of arterial blood (CaO2)?
What is CaO2’s normal range?
normal range = 15-20
How do you find O2 content of arterial blood (CaO2)?
What is CaO2’s normal range?
normal range = 15-20
How do you find the O2 content of mixed venous blood (CvO2)?
What is CvO2’s normal range?
Normal Range = 12-15%
How do you calculate Cardiac Output (CO)?
what is CO’s normal range?
CO = HR x SV
(heart rate x SV)
-SV = stroke volume, blood ejected by ventricles.
NORMAL RANGE = 4-8 L/min
How do you calculate oxygen delivery (DO2)?
What is DO2’s normal range?
DO2 = CO x CaO2
NORMAL RANGE = 1000ml/min
note
you may have to multiply CO by 10 to convert units…
-So it should be [CO(10)] x CaO2 in our class.
How do you calculate mean arterial pressure (MAP)?
[Systolic BP + (2 x Diastolic)] / 3
How do you calculate oxygen extraction ratio (O2 ER)?
Normal range for O2 ER?
C(a-v)O2/ CaO2
Normal value: 0.25 (tissue extracts 25% of CaO2)
How do you calculate O2 content?
O2 content = (PO2) (0.003) + (Hb content) (1.34) (Hb02% sat)
What is the Alveolar air equation (PaO2)?
[(PB-47) X FiO2] – (PaCO2/0.8)
What limit affects us from using 0.8?
-when fi02 is greater than or equal to 0.6
What is the A-a gradient?
more specifically the equation?
PA02- Pa02.
Norm = 5-10
P/F Ratio?
PaO2/FiO2
Normal > 400
How do you calculate O2 consumption (VO2)?
Normal value for O2 Consumption?
VO2 = CO x C(a-v)O2
Normal value = 250 mL/min
Ventilation/perfusion ratio (V/Q)?
Normal value + absolute dead space/shunt?
Ventilation/cardiac output
How do you calculate the dead space to tidal volume ratio (Vd/VT)?
(Vd/VT) = (PaCO2 - PeCO2) / PaCO2
Normal Value = 20-40%
How do you calculate alveolar ventilation (Va)?
Va = (Vt - Vd) x F
F = respiratory rate
How do you calculate minute ventilation (Ve)?
(Vt x F)
What are the formulas for the following:
Transpulmonary pressure
Transthoracic pressure
Transairway pressure
Focus of question: what do each describe?
(edit later)
Hydrostatic pressure formula
Phydro = gravity x density x height
G = 9.81
D = 1000 (if unknown)? Other wise D=m/v
Tobins score
Normal range < 100
RR / Vt (in Litres)
What is the purpose of Tobin’s score?
Spontaneous breathing trial
How does 2-3 DPG (diphoshoglycerate) effect the Oxyhemoglobin Curve?
2,3 DPG is a molecule that makes O2 to Hb bind weaker.
- w/o DPG the binding will be too strong which causes no unloading of O2
- Increased lvls during alkalosis, chronic hypoxemia, anemia
- Decreased lvls durign acidosis
Oxyhemoglobin Curve: What does a right shift imply?
Decreased affinity for O2 caused by:
- Acute acidosis
- high CO2 (Bohr effect)
- Increased temp
- Increased 2,3 DPG
- Abnormal hemoglobin’s
Oxyhemoglobin Curve: What does a left shift imply?
Increased affinity for O2 caused by:
- Acute alkalosis
- decreased PCO2 + increased O2 (Haldane effect)
- Decreased temp
- low levels 2,3 DPG
- Carboxyhemoglobin
- Methemoglobin
- Abnormal hemoglobin
- fetal Hb
Oxyhemoglobin Curve: What does affinity for O2 mean?
- What do left and right shifts in the curve mean?
High affinity promotes O2 uptake by Hb
Low affinity promotes O2 drop off by Hb
