Flashcards in M5 Equations Deck (44):

1

## Alveolar Gas Equation

### PAO2 = FIO2 (PATM – PH2O )– PaCO2 / RQ

2

## Dead Space (Bohr Equation)

### VD/VT = (PaCO2 –PECO2) / (Pa CO2)

3

## Ohm’s Law

### Pressure Gradient = Air Flow x Airway Resistance

4

## Airway Resistance for Laminar Flow (Poiseuille’s Law)

### Laminar Flow Resistance = (8 Length • Viscosity of gas) / (πRadius^4 )

5

## Reynold’s Number

###
￼R = (Velocity x Density x Diameter) / (Viscosity)

>2000 consistent with turbulent flow

6

## Static Compliance

### Static compliance = Volume/Pressure = (Tidal volume delivered) / (Plateau pressure – PEEP)

7

## Dynamic Compliance

### Dynamic compliance = Volume/Pressure = (Tidal volume delivered) / (Peak pressure – PEEP)

8

## Law of LaPlace

###
Pressure = (2 • Wall Tension) / (Radius)

Note: wall thickness is typically not considered for alveoli

9

## Transpulmonary Pressure

### Transpulmonary pressure = Alveolar pressure – Pleural pressure

10

## Transthoracic Pressure

### Transthoracic pressure = Pleural pressure – Atmospheric pressure

11

## Predicted PaO2 by Age

### Predicted PaO2 = 110-(age • 0.4)

12

## Boyle’s Law

### Pressure1 • Volume1 = Pressure2 • Volume2

13

## Ohm’s Law

### Pressure = Cardiac Output • Resistance

14

## Myocardial Perfusion Pressure

### MPP = Aortic diastolic pressure – LVEDP

15

## LaPlace Law

###
Tension = (Pressure • Radius)/(2 • Wall Thickness)

Note: Notice that as opposed to the equation in the Respiratory Section, the equation is solved for wall tension

16

## Poiseuille’s Law

###
Flow Rate = (π • Pressure • radius4)/(8 • viscosity • length)

Note: Notice that as opposed to the equation in the Respiratory Section, the equation is solved for flow.

17

## Fick Principle

###
CO = VO2/(CaO2 – CmvO2)

VO2 = Oxygen consumption

CaO2 = Arterial content of oxygen

CmvO2 = Mixed venous content of oxygen

18

## Consumption of Oxygen

###
VO2 = Hb • (Sata - Satmv) X 1.34 • CO

Rearranged: Satmv = Sata – [VO2/ (Hb • 1.34 • CO)]

19

## Arterial Content of Oxygen

### CaO2 = [Hb • Sata • 1.34] + 0.003 • PaO2

20

## Respiratory Quotient

###
RQ = VCO2/VO2

VCO2 = Elimination of CO2

VO2 = Oxygen consumption

21

## Oxygen Delivery

###
DO2 = CaO2 • CO

CaO2 = Arterial content of oxygen

22

## Oxygen Extraction Ratio

### ER = VO2/DO2

23

## Pulmonary Vascular Resistance

###
PVR = [(PAP-Wedge)/CO] • 80

PAP = Pulmonary Arterial Mean Pressure

24

## Stroke Work

### SW = Stroke volume • mean arterial pressure

25

## Cardiac Index

### CI = CO/BSA

26

## Systemic Vascular Resistance

### SVR = [(MAP-CVP)/CO] • 80

27

## Starling Equation

###
Q = kA X [(Pc – Pi) + σ(πi-πc)]

Q = Net Fluid Filtration

k = Capillary Filtration Coefficient (of water)

A = Area of the Membrane

σ = Reflection Coefficient (of albumin)

Pc = Capillary Hydrostatic Pressure

Pi = Interstitial Hydrostatic Pressure

πi = Interstitial Colloid Osmotic Pressure

πc = Capillary Colloid Osmotic Pressure.

28

## Allowable Blood Loss

###
ABL = EBV X [(Hb – Minimum allowable Hb)/Hb]

EBV = Estimated Blood Volume

29

## Cerebral Perfusion Pressure

### CPP = MAP – ICP

30

## Perfusion Pressure

### PP = MAP – Venous Presure

31

## Volume of Distribution

### VD = Dose / Concentration

32

## Half Life

### Half-life = Volume of distribution / Rate of clearance

33

## Clearance

###
￼￼Clearance = dose / area under time concentration curve

Clearance = (Urine concentration x Urine flow) / (Plasma concentration)

34

## Opioid Conversions

###
Drug IV Oral

Morphine 10 mg 30 mg

Hydromorphone 1.5 mg 7.5 mg

Fentanyl 100 mcg NA

Codeine N/A 200 mg

Hydrocodone NA 30 mg

Oxycodone NA 20-30 mg

35

## Gas Tanks (E)

###
Gas Volume Pressure

Oxygen 625 L 2200 psig

Nitrous Oxide 1590 L 745 psig

36

## Incidence & Prevalence

###
Incidence = Number of occurrences / Sum of person-time at risk

Prevalence = Number of cases/ Number of individuals sampled

37

## Measure of Effect

###
Absolute measure of effect = Rate Difference = Rate of risk exposed – Rate of risk not exposed

Relative measure of effect = Rate Ratio = Rate of risk exposed /Rate of risk not exposed

38

## Sensitivity

### Sensitivity = TP/ (TP + FN)

39

## Specificity

### Specificity = TN/ (TN + FP)

40

## PPV

### Positive Predictive Value = TP/ (TP + FP)

41

## NPV

### Negative Predictive Value = TN/ (TN + FN)

42

## Odds Ratio

### Odds Ratio = AD/BC

43

## Relative Risk

### Relative Risk = [A/(A+B)] / [C/(C+D)]

44