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Physics > 4. Gas Supply & Delivery > Flashcards

4. Gas Supply & Delivery Flashcards

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1
Q

Boyles law

A

At a constant temperature the volume of a fix mass of gas is inversely proportion to its pressure
PV=K or V =1/P
Oxygen available in cylidner

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2
Q

Charles law

A

At a constant pressure - volume of gas directly proportional to abs temperature
V proport T

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3
Q

Gay-Lussacs / 3rd gas law

A

Constant volume, absolute pressure of gas directly proport to abs temp
P/T=K, P proport T
Hydrogren thermoter

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4
Q

Henrys Law

A

amt dissolved gas in a liquid is proportional to its PP above the liquid
the bends / hyperbaric o2

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5
Q

Daltons law

A

Mixture of gases = pressure each exerts is the same as it would exert if it alone occupied the volume

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6
Q

Define solid liquid gas

A

All sub - atoms/ compounds ‘molecules’

Solid - arranged tight lattice - strong forces between molecules - contin motion oscilating mean positon

Liquid more energy than solid -
molecules free to move thru liquid -
weaker van der waals forces

Gas -
escaped van der waals forces -
free to move individually

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7
Q

Universal gas law

A

Combine Boyle & Charles
Presure c volume = number of moles of gas x universal constant c temperute
PV=nRT

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8
Q

Critical Temperature

A

Temperature above which a gas cannot be liquefied no matter how much pressure applied

oxygen -118

No2 36.5

Co2 31

Temp below - sub exists liq and vapour

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9
Q

Critical pressure

A

Pressure required to liquefy a gas at its crit temp

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10
Q

Gas V Vapour

A

Gas is above crit temp

Vapour -
gaseous form at temp below crit temp

gas cannot be liquefy

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11
Q

Avagadro’s constant

A

Equal volumes of gases under STP containt same number of molecules
Diff molec weight - actual mass different

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12
Q

Mole

A

quant sub cotain= number molecules as atoms .012g C12
6.022 x 10^23
1 mole of any gas at stp 6.022 x 10^23 & occupy 22.4l

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13
Q

Flow
what is it
how measured

A

Quantity of fluid passing point per unit time
gas or liquid
L or ML per Min or Hour

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14
Q

Laminar flow

how does the fuid move

which is fastest

what does halving diameter do?

is there flow on the vessel wall?

A 
Fluid move smoothly
Molecules moving parallel
Smooth tubes @ low flow rates
Concentric ring - fastest in centre x2 fast sides
Frictional forces sides - slowing

halving diameter - decrease 16 fold

No flow apporach walls vessel

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15
Q

Turbulent flow

A

Disordered - swirls eddies & vortices
Irregular tubes @ constriction, corner, narrowing / fast flow rates
Less efficient - conversion laminar to turbulent = reduce flow for given pressure drop

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16
Q

Hagen-Poiseuille

A 
= Delta P Pi  Radius ^4 / 8 n L
Newtonian fluids (constant viscosity)
FLow proport change pressure,
inversere to length
radiues fourth power
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17
Q

Viscosity v Density

A

Viscosity - resistance to flow

Density Mass substance / unit volume

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18
Q

Reynolds number

A

Dimensionless number
Predict if flow will turbulent or laminar

vpD/n

liner velocity x density x diameter divide viscosity
<2000 - linear
2000-4000 - usually turb
>4000 turbulent

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19
Q

Decrease WOB w/ flow

A

Heliox - less dense x5 vs air - improve flow

Big ETT

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20
Q

Bernoulli principle

A

Increase in velocity of fluid - simultaneous w/ decrease in pressure difference

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21
Q

Bernoulli effect demonstrated

A

Fluid flow flow thru constriction in tube / aerofoil surf

Fluid flow down tube - 2 energy -
kinetic energy - how quick flowing
Potetnial energy pressure drop

At narrow - velocity increase - kinetic energy increase

Potential energy must decrease = pressure drop

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22
Q

1st Law of thermodynamics

A

total energy universe - same

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23
Q

Cylinders
Anaes machine

Oxygen cylinders size? Increments
C - D - E volume

N2o - cylinderes
C - D - E

Entonox Sizes

A

E is fitted to anaes

O2 - C->j
Volume doubles
D 340l E 680l

N2O
C 450 D 900 E 1800

Entonox D G J

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24
Q 
Mapleson A
Draw
Efficient
Also called
Min FGF
A

Efficient spont ventilation - min FGF of 70ml/kg.min
Magill / Lack (Coaxial)
Not suit <25kg
increased dead space at the distal / patient end

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25
Q 
Mapleson D
Draw
Efficient
Also called
Min FGF
A

Bain - coaxial D
Controll vent 70mls/kg/min to maintain normocapnia
Ineff during SV

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26
Q

Mapleson E &; F
draw

another name for each

when can be used

whats the fgf

A 
E - ayres t piece
F - Jackson rees mod
paeds <20kg - low resistancew
FGF x2-3 mv  - SV
No resevoir bag
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27
Q

Humphrey ADE system

A

Mapleson A, D or E dependent on position

28
Q

HFNO
What is it?

What can it do

benefits x4

A

Humidified, titrated oxygen therapy matching or even exceeding the patients’ inspiratory flow rates.

high-flow oxygen delivery system that provides up to 60 litres per minute of warmed and humidified gas enabling an accurate delivery of an FiO2 of between 0.2 and 1.0 irrespective of the patient’s peak inspiratory flow rates.

Benef 
A reduction of anatomical dead-space by increasing pharyngeal washout
Reduced work of breathing
Provides an element of CPAP
Improvement of mucociliary clearance.
29
Q

Is SVP affected by ambient temperature

A

saturated vapour pressure (SVP) of a volatile agent is unaffected by ambient pressure.).

30
Q

SVP of sevoflurane

A

at a temperature of 20°C is approximately 21 kPa or 21% of the atmospheric pressure (100 kPa)

31
Q

% vaporiser output

A

% vaporiser output = % calibrated x (calibrated pressure/ambient pressure)

At standard atmospheric pressure the vaporiser output = 2% x (100kPa/100kPa) = 2%

At an atmospheric pressure of 200kPa the vaporiser output = 2% (100kPa/200kPa) = 1%

The clinical effects of the volatile agents are determined by their partial pressure in
tissues. Ultimately the output of the vaporiser is unaffected as the partial pressure of the volatile agent delivered is the same at each ambient pressure ( 2% of 100kPa = 2kPa and 1% of 200kPa=2kPa)

32
Q

Lack system or coaxial Mapleson A

A

Mod A fresh gas flows through an outer tube (30 mm) and exhaled gases flow through the inner tube (14 mm).

33
Q 
APL
What is it
What is the function
How does it work
Pressure needed during during SV
The disc
A

adjustable pressure limiting valve / expiatory valve allows exhaled gas & excess fresh gas to leave the breathing system.

3 ports - inlet - patient - exhaust

It is a one-way,
adjustable spring-loaded valve,
gases escape - pressure exceeds the valve opening pressure.

During spontaneous ventilation a pressure of less than 1 cm of water (0.1 kPa) is needed when the valve is in the open position (not 2 cm of H2O).

The disc rest on knife edge seating Hydrophobic
Stop condensation cause stick

34
Q

Resevoir bag - pressure limit

Why (what law)

A

The reservoir bag is highly compliant and when over inflated, the rubber bag can limit the pressure in the system to about 40 cm of H2O.

This is due to the law of Laplace, which states that the pressure will fall as the radius of the bag increases:

Pressure = 2 x tension/radius.

35
Q 
VIE
Use
What is it
How is it stored**
How does it work

Positioned on

Safety valve @ what pressure

Pressure regulator

A

Vacuum insulated evaporator

Supply + Store O2

Thermally insulated container
vacuum shell
insulate 1500 litres O2

As liquid, @ temp -170 to -150 C, pressure 5-10atm (beneath crit temp)

Latent heat vaporisation, taken liquid O2 in

VIE - low temp

Weighing balance - measure mass liquid (resupply from tanker)
safety release 15bars

1700kpa - allows o2 to escape

Pressure regulator maintains the pressure of the gas entering into the pipeline at 400 kPa.

36
Q

Helium
Properties

BP, density, solubility

Supplied

Affect vaporiser?

A

Inert gas - found air 5.25 ppm
Second lightest - atomic no 2 & wt 4.0026

Low boiling point, low density, low solubility and high thermal conductivity.
Has a density of 0.1785 g/L at 20oC, which is less than nitrogen.
Is the least soluble of all gases in water.

Brown cylinder 137 bar
Mix w/ O2 - brown / white quart shoulder

Negligible

37
Q

Non return pressure valve

A

Protect Vaporiser & flow meter from back pressure

Downstream of vaporiser

38
Q

Emergency flush

A

bypasses vaporiser & flow meter @45l min & 4 bar

39
Q

Flow meter panel

A

O2 last to added to back bar

sit left but last aded

40
Q

O2 Cylinder colour & pin index

A

Oxygen - Pin index 2+5, black body and white shoulder

41
Q

Air colour & pin index

A
  • Pin index 1+5, grey body and black and white quarter shoulder
42
Q

Nitrous oxide colour & pin index

A
  • Pin index 3+5, blue body and blue shoulder.
43
Q

Soda lime
Biggest componenet
Silicates
Granules

A

Calcium hydoxide mostly
Silicates harden the granules and prevent disintegration.
4-8 mesh
uniform sphere 3-4mm diam

1kg can absorb 120L CO2

larger particles size -= less resistance to flow

can heat to 40C

humdifies Inspired gases

Can produce carboxyhb

44
Q

Formula for Soda lime

A

CO2 + Ca(OH)2 → CaCO3 + H2O + heat

45
Q

Risk w/ soda lime

How it occurs

what does it occur more with

What is another risk
with that type of flow

A

Dry
passing oxygen - long periods,
subsequent use using any of the volatile

Carbon monoxide.

High concentrations CO:
desflurane
enflurane.

CO production from isoflurane is less but still significant.

Also sevoflurane and halothane can produce smaller amounts of CO.

sevoflurane there is the potential for the generation of compound A with low-flow anaesthesia

46
Q

Rotameter consists

A

vertical tapered tube

smallest diameter at bottom

47
Q

Cylinders of compressed vapours and gases have the following pressures when full at 15°C

Oxygen
Entonox
Medical air 
Carbon dioxide 
Nitrous oxide &amp; psi
Cyclopropane
A

13700 kPa
Entonox 13700 kPa
Medical air 13700 kPa

Carbon dioxide 5000 kPa (723 psi)

Nitrous oxide 4400 kPa

Cyclopropane 436 kPa.

48
Q

Pressure for pipeline gas

CO2 & n2o

A

All pipeline gases are supplied at 4 bar (or 400 kPa), but compressed air is also supplied at 7 bar for power tools.

Carbon dioxide and nitric oxide are usually only supplied in cylinders.

49
Q

Adequate ventilation is required in areas where anaesthetic gases

m3/s

recov ery air charnge

A

Operating theatres 0.65 m3/second
Anaesthetic rooms 0.15 m3/second
Preparation rooms 0.1 m3/second.

Recovery rooms require 15 air changes per hour

50
Q

How do HAFOE work

A

Bernoulli principle - speed and kinetic energy and fall in pressure that causes entrainment of large volumes of air into a flow of 100% oxygen into the nozzle of HAFOE masks.

51
Q

How prevent hypoxic mix w/ Nitrous

A

Oxygen - nitrous oxide chain link

two gears connected - as nitrous oxide turned - oxgen flow will turn

min 25%

52
Q

Helium v Nitrogen at depth

A

Nitrogen narcosis - avoid breathing He Oxygen mix

He - 1/2 soluble vs N - less discoled tissue

This wh Helium not use in lower airway obstruction -
flow laminar - depends viscosity and not density

53
Q

Nitrous oxide

Bl:Gas
Mac
Fliing ratio cylinder in uk

crit temp

crit press

boiling point

A 
Bl.Gas - 0.47
Mac 105
Filling ratio .75
Crit temp 36.5 
Crit press 72.6
BP -88
54
Q

Various pin indices

A 
oxygen 2 5
Air 1 5
N2O 3 5
He - no pin 
Entonox 7
55
Q

What are stored in vapour form at room tempreature

A

N20
Entonox
CO2

Not
He
O2

Gas - gasesous at RT - Crit temp is below RT
CT -temp above which cant be liqufy by pressure
below room temp cant be lquefy cant liquefy - store gas

Vapour - gasesous form benath crit temp

CO2 31
+ N2o 31
= vapour at room temp

56
Q

Vaporisers

Resistance

Inside circl

outside circl

A

goldman and oxford mini - inside

in - low resistance

plenum outside - tec

tect mark 3-5 - bimetallic strip outside chamber

interlock selecta tec mark 4+5

Cu give heat gas - maint temp
spec heat cap .39j/g k

57
Q

Coanda
explain

does the fluid need be contionous

A

Point constriction - pressure falls
if at point - touchign wall - nothing entrained as negative pressure spent holding stream ajcanet to wall

Change low - can dislodge - DOESNT need be continous

58
Q

Fluid logic ventilator relies on

A

Coanda effect

fluid - contact curved surface - follow line of surface

altering direction flow

59
Q

Combustion

What stochiometric conc

which is more violent o2 or n2o and o2

where can apg lavel equip be used

A

Stochiometric concentration -
no vapour or oxidising agent once combustion reaction complete
stoch conc diff oxygen and air
explosion violent with n2o and oxygen than pure oxyg

apg label equip can be used zone contains anes mix ocy or ntrious

60
Q

Flow trigger

A

reduce wob vs pressure - always bf gas flow

no dleay inspiratiory valve

61
Q

Flow cycles

A

PS vent - reduction in PIF

62
Q

Volume cycle

A

begin expiration once set tv delivered

63
Q

Cylinders

what used medical

how often tested

whats the plastic disc

A

H not used for medical gases
D E F G J are

tested 5-10years
plastic disc around neck indicated when last tested

64
Q

VIC

VOC

flows and conc

A

VIC low flows - conc higher than dialled up
inflow - unknown conc

VOC - lower than dialled up
monitoring is important
conc depend uptake

65
Q

Is it the poyting affect that causes seperation of entonox

what can prolong use done

what pressure prone to sep

whats the pseudocrit temp

increase temp increases or decreases risk

A

no.
it is Lamination
at temps below pseudocrit -5.5 - liquefaction and seperation - can equal hypoxic mix

poynting - means formed - oxygen buble thru nitrous

prolong use - bm suppresion

117 bar most prone seperation

increase temp decreases risk sep

66
Q

Tec 6

FGF enter?

Dial calibrated how and to what

capacity

Heat what temp

what pressure
whats svp when heat and pressure

A

FGF doesnt enter vape chamber

Dial 0-18%
1%- 12
2% after

Sum cap 450

Heated 39

2atm
when heat 39 - SVP 194

Physics (11 decks)

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