Physics Old Exams Flashcards by Anna Logan

the solubility coefficient most often used in anesthesia is?

Otswald

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effect of giving 3% saline solution on blood volume?

0.9% is normal, so it would expand blood by 3x

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which humidifier is most efficient?

ultrasonic nebulizer

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what is the normal osmotic pressure of blood colloids?

30 mmHg

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what will the effect be when infusing 1 L of fluid @ 4*C into a 70kg patient?

drops body temp by 0.5*C

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The solubility of a substance at a given temperature is described by which law?

Henry’s law

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the partial pressure of isoflurane in tissue at 1 MAC

(1.15 x 760) / 100 = 8.7mmHg

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calculating combined MAC of nitrous with other agents

(N₂O flow / total flow) = MAC N₂O + other agents

ex. 1.5% Iso + 36% Nitrous

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blood pressure required for efficient brain function….. kidney function

MAP = 60mmHg –Brain

MAP = 70mmHg –Kidneys

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Desflurane vaporizer is classified as what type?

dual circuit

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define specific heat

amount of energy (calories) required to raise the temp of 1g of a substance by 1*C

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law which describes heat transfer from electromagnetic radiation

steffan-boltzman

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Duration of O₂ from a E cylinder when pressure is 750 on gauge if running at 5 L/min

Full E cylinder has P= 2200psi V=660L

Using daltons law : V2 / V1 = P2 / P1

V2 = P2/P1 x V1 = 750/2200 x 660 = 225L

5 L/min would last : 45 min

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what is the concentration of saturated isoflurane within the vaporizing chamber of a vaporizer at RTP?

31%

241/760 = 31%

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normal human serum has an osmotic pressure approximately equal to how many atmospheres?

8 atm

0.3 osm x 25.4 L = 8 atm

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what is the value of normal urine osmolarity?

1000 mosm/L

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what is the water vapor pressure in the trachea at 37*C?

47 mmHg

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the movement of a substance across a unit area (M/x), is described by which law?

Fick’s law

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What is normal plasma osmolarity?

285 mosm/L

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which anesthetic agent would have he slowest build up of alveolar concentration (at 1 MAC inspired concentration)?

Halothane

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using the “vaporizer equation,” determine how much oxygen must flow through the vaporizing chamber in order to provide a set percent of agent at a fixed gas flow

VO2= [Va (Pbar - VPa)] / VPa

Va = % agent delivered (2% halo @ 5 lpm = 5000ml x 0.02)

VPa = vapor pressure of anesthetic

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What kind of vaporizer is this?

tec 4

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what kind of vaporizer is this?

tec 5

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what kind of vaporizer is this?

tec 6

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calculation of MAC percent at various altitudes (formula)

(actual mmHg for 1 MAC) / (barometric pressure)

graph of uptake of agents. list from top to bottom in terms of speed of uptake

N2O Des Sevo Iso Halothane

actual heat capacity of human tissue is what multiple of water?

0.85

why are large quantities of metal used to make anesthetic vaporizers?

high heat capacity and high metal (thermal) conductivity

what uses conductivity to measure a temperature change?

thermistor and heated wire

what is the max diameter (in micrometers) of water particles that are deposited in the alveoli?

3.0 mcm

osmotic pressure induces motion of what?

the solvent

what effect will limited pulmonary diffusion capacity have on CO2 and O2?

more likely to become hypoxic than hypercarbic (CO2 diffusion is quicker than O2)

what is the relative importance of factors determining the diffusion of drugs

concentration & pressure gradient solubility molecule size liquid vs. gas

what does the second gas effect do?

potent agents delivered with N2O so that they will be delivered in a greater concentration to the alveoli as N2O is absorbed by pulmonary blood (only for ~2 breaths)

atelectasis =?

shunt

one mol of gas at RTP will occupy what volume?

24L 22. 4L @ STP 25. 4L @ BTP

what effects do hydrostatic pressure changes have on the blood pressure?

+/- 1.8 per inch moved

how many liters are in an adult circuit?

What is a dalton?

A unit used in expressing the molecular weight of proteins, equivalent to atomic mass unit.

P = F/a

Who's law deals with circles?

Leplace's Law

What is Laplace's Law?

P = T/R (cylinders) P = 2T/R (spheres)

Smaller aveoli would collapse into larger aveoli if not for what? This is an example of who's law?

Surfactant Laplace's Law of P = 2T/R

What is the Fruahast-Linquist Effect?

When RBCs line up in small vessels, lowering the viscosity, and thus increasing flow through the vessel

Give the equation and tell whos equation describes laminar flow? What is the number for laminar flow?

Q = π Pr^4 / 8 n l Hagen-Poiseuille equation Reynolds number of \< 2000

Give the equation and tell whos equation describes turbulent flow? ## Footnote What is the number for turbulent flow?

Q^2 = K P 4 π^2 r^5 / p l Fanning equation Reynolds number \> 2000

What is Bernoulli's Equation and what does it give us?

E = P + pgh + 1/2 pv^2 Energy of a fluid

V1 x a1 = V2 x a2 is what equation?

Continuity equation

What does HAFOE mask stand for?

High Air flow with oxygen Entrainment mask L of Air entrained / liters of oxygen EQUATION: 1.0 - FiO2 / FiO2 - 0.21

What is always true about flow? what is usually true about flow?

ALWAYS TRUE: flow is from area of higher energy to area of lower energy Usually true: flow is from area of higher pressure to area of lower pressure

Boyles Law

TB: temp constant V1 / P1 = V2 / P2

Charles Law

CP: constant pressure V1 / T1 = V2 / T2

Don's Law

VD: volume constant P1 / T1 = P2 / T2

Vx / Vy = Px / Py is what equation?

Dalton's Law of Partial pressures

What is the filling ration in the US of N2O ?

0.68

What are STP conditions?

T : 273 K 0\* C P : 760 mmHg 1 mol occupies 22.4 L

What are RTP conditions?

T: 293 K 20\* C P : 760 mmHg 1 mol occupies 24.0 L

What are BTP conditions?

T: 310 K 37\* C P : 760 mmHg 1 mol occupies 25.4 L

Know how to calculate how much N2O left available in cylinder

Take weight of N2O cylinder: 3.4 kg at STP Weight of N2O : molecular weight (N= 14 x 2, O= 16) = 44gm 3400 g x 1 mol/ 44g = 77.27 mol 77.27 mol x 22.4 L / mol = 1730.9 L

What is the partial pressure of O2 (PaO2) when patient on room air (0.21 O2)?

100 mmHg

What is the partial pressure of O2 (PaO2) when patient on 50% O2?

300 mmHg

What is the partial pressure of O2 (PaO2) when patient on 100% O2?

660 mmHg

How much V-Q mismatch does the average patient have?

10-20%

What is the alveolar oxygen equation?

PaO2 = FiO2 (Pb - PaH2O) - (PaCO2 / R) where R = 0.8

# Define the critical temp of something? What is critical temp of N2O?

Temperature above which liquidification cannot occur 36.5\* C

What is the heat of vaporization?

amount of heat (calories) required to convert 1 gram of liquid agent into a vapor

What is O2 solubility in plasma?

0.0031

How long is the diffusion time from blood to lung of CO2?

0.2 seconds

How long is the diffusion time of O2 from the lung to the blood?

0.4 seconds

Easy conversion from kPa to mmHg?

1 kPa = 7.5 mmHg