Formulas & Numbers

Question 1

Boyle’s Law

Answer 1

P1V1 = P2V2

Question 2

E-Cylinder

Answer 2

1900-2200psi
Full tank 660L
660L/1900psi = 0.35 x psi (available) = L
14.7psi = 5L
Available L / (L/min) = min

Question 3

Poiseuille

Answer 3

Laminar flow

π ⋅ ΔP ⋅ r^4) / (8 ⋅ η ⋅ l

Question 4

Oxygen %

Answer 4

Mixed air 0.21 x L

O2 + Air / Total L = %

Question 5

N2O Tank

Answer 5

745psi:1590L

Full 20.7kg
Empty 14.1kg

Question 6

Convert lbs → kg

Answer 6

lbs/2 = xy - x = kg
lbs/2 = xyz - xy = kg

Question 7

BMI

Answer 7

weight (lbs) / height (in^2) x 703 = kg/m^2

Question 8

LMA Sizes

Answer 8

3 (30-50kg) 20cc/30cc
4 (50-70kg) 30cc/45cc
5 (70-90kg) 40cc/60cc

Question 9

Cricoid Pressure

Answer 9

Start w/ 3lbs then increase to 6.6-8.8lbs (3-4kg)

Question 10

Height → cm

Answer 10

Height (inches) x 2.5 = cm

Question 11

Men IBW

Answer 11

Height (cm) - 100 = IBW kg

Question 12

Women IBW

Answer 12

Height (cm) - 105 = IBW kg

Question 13

Bispectral Index Score

Answer 13

BIS ranges from 0-100
100 = awake
>70 = ↑recall risk
40-60 = general anesthesia
0 = isoelectric EEG

Question 14

SpO2

Answer 14

HbO2 / (HbO2 + Hg) x 100%

Question 15

TOF Twitches

Answer 15

4 twitches = 70% blocked
3/4 75%
2/4 80%
1/4 90%
0/4 100%

Question 16

Flexion/Extension ETT

Answer 16

Moves ETT 1.9cm

Question 17

Rotation ETT

Answer 17

Moves ETT 0.7cm

Question 18

Ideal ETT Placement

Answer 18

2cm above the carina

Question 19

Autotransfusion

Answer 19

Lithotomy or Trendelenburg position

250-300mL/leg when elevated

Question 20

SaO2:PaO2

Answer 20

90: 60
75: 45
60: 30

Question 21

Heat Loss Mechanisms

Answer 21

Radiation 40%
Convection 30%
Conduction
Evaporation

Question 22

Maintenance IVF

Answer 22

4-2-1
4cc/kg/hr 1st 10kg
2cc/kg/hr 2nd 10kg
1cc/kg/hr each additional kg

Any patient > 20kg
Weight + 40

Question 23

Fluid Deficit Replacement

Answer 23

MIVF x NPO (hrs)
Replace 1/2 deficit 1st hour + MIVF
Replace 1/4 deficit 2nd hour + MIVF
Replace remaining 1/4 deficit 3rd hour + MIVF

Question 24

Evaporative Loss (3rd Space)

Answer 24

Minimal 0-2mL/kg/hr
○ Eye, lap chole, hernia, knee scope
Moderate 3-5mL/kg/hr
○ Open chole or appendectomy
Severe 6-9mL/kg/hr
○ Bowel surgery or total hip replacement
Emergency 10-15mL/kg/hr
○ Gun shot or MVA

Question 25

Estimating Blood Loss

Answer 25

• 1gm = 1cc
• Soaked gauze 4x4 = 10cc
• Ray-tech = 10-20cc
• Soaked laparotomy pads = 100-150cc
• Wet sponges 20-30% dry value
Floor spill approximations:
	○ 1" = 5mL
	○ 2" = 20mL
	○ 3" = 45mL
	○ 4" = 80mL

Question 26

Estimated Blood Volume

NEONATES

Answer 26

Premature 95mL/kg

Full term 85mL/kg

Question 27

Estimated Blood Volume

INFANTS/CHILDREN

Answer 27

Infants 80mL/kg

Children 75mL/kg

Question 28

Estimated Blood Volume

ADULTS

Answer 28

M 75mL/kg

F 65mL/kg

Question 29

Estimated Blood Volume

ELDERLY

Answer 29

M 65mL/kg

F 60mL/kg

Question 30

Allowable Blood Loss

Answer 30

[EBV x (starting Hct - allowable)] / Patient starting Hct

Question 31

Massive Transfusion

Answer 31

• Replace total patient blood volume in <24hr
• Acute admin >1/2 patient’s EBV in 3hr or less
• Transfusion 10 units RBCs in 24hr

Question 32

PRBC

Answer 32

1 unit ↑Hgb 1g/dL↑Hct 2-3%

Question 33

Platelets

Answer 33

1 unit (200-400mL)
↑platelet count 7,000-10,000 1hr after admin

Question 34

FFP

Answer 34

1 unit (200-250mL)
↑clotting factors 2-3%