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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
``` Mapleson D Draw Efficient Also called Min FGF ```
Bain - coaxial D Controll vent 70mls/kg/min to maintain normocapnia Ineff during SV
26
Mapleson E &; F draw another name for each when can be used whats the fgf
``` E - ayres t piece F - Jackson rees mod paeds <20kg - low resistancew FGF x2-3 mv - SV No resevoir bag ```
27
Humphrey ADE system
Mapleson A, D or E dependent on position
28
HFNO What is it? What can it do benefits x4
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
Is SVP affected by ambient temperature
saturated vapour pressure (SVP) of a volatile agent is unaffected by ambient pressure.).
30
SVP of sevoflurane
at a temperature of 20°C is approximately 21 kPa or 21% of the atmospheric pressure (100 kPa)
31
% vaporiser output
% 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
Lack system or coaxial Mapleson A
Mod A fresh gas flows through an outer tube (30 mm) and exhaled gases flow through the inner tube (14 mm).
33
``` APL What is it What is the function How does it work Pressure needed during during SV The disc ```
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
Resevoir bag - pressure limit | Why (what law)
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
``` VIE Use What is it How is it stored** How does it work ``` Positioned on Safety valve @ what pressure Pressure regulator
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
Helium Properties BP, density, solubility Supplied Affect vaporiser?
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
Non return pressure valve
Protect Vaporiser & flow meter from back pressure | Downstream of vaporiser
38
Emergency flush
bypasses vaporiser & flow meter @45l min & 4 bar
39
Flow meter panel
O2 last to added to back bar | sit left but last aded
40
O2 Cylinder colour & pin index
Oxygen - Pin index 2+5, black body and white shoulder
41
Air colour & pin index
- Pin index 1+5, grey body and black and white quarter shoulder
42
Nitrous oxide colour & pin index
- Pin index 3+5, blue body and blue shoulder.
43
Soda lime Biggest componenet Silicates Granules
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
Formula for Soda lime
CO2 + Ca(OH)2 → CaCO3 + H2O + heat
45
Risk w/ soda lime How it occurs what does it occur more with What is another risk with that type of flow
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
Rotameter consists
vertical tapered tube | smallest diameter at bottom
47
Cylinders of compressed vapours and gases have the following pressures when full at 15°C ``` Oxygen Entonox Medical air Carbon dioxide Nitrous oxide & psi Cyclopropane ```
13700 kPa Entonox 13700 kPa Medical air 13700 kPa Carbon dioxide 5000 kPa (723 psi) Nitrous oxide 4400 kPa Cyclopropane 436 kPa.
48
Pressure for pipeline gas CO2 & n2o
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
Adequate ventilation is required in areas where anaesthetic gases m3/s recov ery air charnge
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
How do HAFOE work
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
How prevent hypoxic mix w/ Nitrous
Oxygen - nitrous oxide chain link two gears connected - as nitrous oxide turned - oxgen flow will turn min 25%
52
Helium v Nitrogen at depth
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
Nitrous oxide Bl:Gas Mac Fliing ratio cylinder in uk crit temp crit press boiling point
``` Bl.Gas - 0.47 Mac 105 Filling ratio .75 Crit temp 36.5 Crit press 72.6 BP -88 ```
54
Various pin indices
``` oxygen 2 5 Air 1 5 N2O 3 5 He - no pin Entonox 7 ```
55
What are stored in vapour form at room tempreature
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
Vaporisers Resistance Inside circl outside circl
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
Coanda explain does the fluid need be contionous
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
Fluid logic ventilator relies on
Coanda effect fluid - contact curved surface - follow line of surface altering direction flow
59
Combustion What stochiometric conc which is more violent o2 or n2o and o2 where can apg lavel equip be used
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
Flow trigger
reduce wob vs pressure - always bf gas flow | no dleay inspiratiory valve
61
Flow cycles
PS vent - reduction in PIF
62
Volume cycle
begin expiration once set tv delivered
63
Cylinders what used medical how often tested whats the plastic disc
H not used for medical gases D E F G J are tested 5-10years plastic disc around neck indicated when last tested
64
VIC VOC flows and conc
VIC low flows - conc higher than dialled up inflow - unknown conc VOC - lower than dialled up monitoring is important conc depend uptake
65
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
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
Tec 6 FGF enter? Dial calibrated how and to what capacity Heat what temp what pressure whats svp when heat and pressure
FGF doesnt enter vape chamber Dial 0-18% 1%- 12 2% after Sum cap 450 Heated 39 2atm when heat 39 - SVP 194

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