Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
49 Cards in this Set
- Front
- Back
|
Vapor=
|
Gaseous phase of a substance that is normally a liquid at room temp and standard pressure
|
|
|
VP=
|
pressure exerted by the molecules in the vapor state.
Equilibrium is reached when # of molecules in vapor state remains constant. |
|
|
VP, dependent upon what? Independent of what?
|
VP is DEPENDENT on the specific liquid and temp and INDEPENDENT of atmos pressure
|
|
|
If you inc temp...
|
more molecules are in vapor phase, inc VP
|
|
|
If you dec temp...
|
More molecules remain in liquid phase and VP decreases
|
|
|
Temperature ______ as heat is ______ during vaporization
|
Falls
Lost |
|
|
BP=
|
temp at which VP = atmos pressure
The lower the atmos pressure, the lower the BP. |
|
|
Liquids with high VP are the most ______ and have the lowest _____ at any temp
|
Most volatile
Lowest BP |
|
|
What is the VP of Des?
|
669...therefore low BP (22.8)
|
|
|
What is Daltons law of partial pressures?
|
In a mix of gases, each gas exerts its own pressure independent of the pressure of the other gases.
The total pressure is the sum of the pp's |
|
|
According to Daltons law, the sum of the pp's=
|
atmospheric pressure under normal conditions
|
|
|
Conc of gas can ge expressed as what 2 things?
|
1. Absolute pressure
2. Volumes percent |
|
|
Absolute pressure=
|
pp in mmHg or torr
|
|
|
Volumes percent=
|
pp/total pressure x 100
|
|
|
Administration of gases is in ____ ____, but uptake is related to ____ _____
|
Admin of gases in volumes percent; uptake directly related to absolute pressure and indirectly to volumes percent
|
|
|
Latent heat of vaporization=
|
# calories needed to convert 1 gm (or ml) into a vapor.
Inversely related to temp |
|
|
Lower temp, _____ heat required for vaporization
|
More
|
|
|
Specific heat=
|
# calories needed to raise temp of 1 gm of substance 1C.
|
|
|
Specifc heat of an inhalation agent indicates....
|
how much heat must be added to maintain a constant temp for vaporization.
The higher the spec heat, the greater the amt of heat that is needed to maintain a given temp |
|
|
Materials with a high specific heat....
|
will change temp slowly and provide a stable environment for vaporization
|
|
|
What does thermal conductivity measure?
|
The speed of heat flow thru a substance
Higher TC= better the heat conduction Lower TC= poorer the heat conduction (good insulator) |
|
|
What are the 2 minimal requirements of a vaporizer?
|
1. Dilution of anesthetic vapor to a therapeutic conc
2. Compression for heat lost during vaporization process (i.e. addition of copper or bronze) |
|
|
How does a copper kettle vaporizer work?
|
Carrier gas (O2) enters bottom, "bubbles up" thru liquid anesthetic, picking up anesthetic vapor (smaller bubbles pick up more)
Exit vapor but must be diluted to an ok conc by a larger FGF |
|
|
What is the percentage of Iso at STP? Iso: VP= 238 torr
|
238/760 x 100= 31%
|
|
|
If 100ml O2 enters vaporizer, how much Iso (31% conc) will leave?
|
100/.69 = x/.31
x(.69) = 31 x= 45 ml Iso |
|
|
What total gas flow of Iso (45ml) is needed to reduce Iso to 1%?
|
X LPM x (1%) = 45ml Iso
X= 45/0.01 X= 4.5 LPM |
|
|
T/F:
Copper Kettles provide flow and temp compensation? |
FALSE
If FGF is reduced, Iso conc will Increase!! If temp of liquid decreases, the final conc will decrease |
|
|
Copper kettles lack ____ _____
|
agent specificity
|
|
|
How does a variable-bypass vaporizer work?
|
FGF enters vaporizer and split in two:
20% FGF enters vaporizing chamber wehre it is saturated w/anesthetic vapor 80% TGF bypasses the vaporizer and rejoins the first portion as it leaves the vaporizing chamber, diluting it down to therapeutic conditions |
|
|
Can you control the amt of gas entering the vaporizing chamber?
|
Yes, the conc control dial controls this and thus the conc of anesthetic
|
|
|
The splitting ratio of FGF is dependent on what 3 things?
|
Anesthetic agent
Temp Selected Conc |
|
|
Temp compensation in vaporizers allow...
|
MORE gas to enter when temp DECREASES
LESS gas to enter when temp INCREASES Accurate w/in 15-35C |
|
|
Vaporizers are ____ _____ and cannot be interchanged. They hold about _____ml w/dry wick
|
Agent specific
Hold ~300ml |
|
|
2 things that affect vaporizer output
|
1. FGF <500ml or >15 LPM
2. If carrier gas is not O2 and is N2O In both cases, the vaporizer output is < set concentration |
|
|
Vaporizers are usually calibrated with air. What happens if it is calibrated with 100% O2, or with 70% N2O?
|
100% O2--output is 4-10% higher
70% N2O-- output is 5-10% lower |
|
|
What can back pressure from a vaporizer be caused by?
|
Positive pressure ventilation
o2 flush valve Both cause a higher output than dial setting |
|
|
Back pressure in vaporizer is WORSE with...
|
low FGF
low conc dial settings low levels of liquid anesthetic fast RR High PIP Rapid dec in pressure during expiration |
|
|
How does Ohmeda vs NAD prevent back pressure (pumping effect) of vaporizers?
|
Oh--one way check valve at vaporizer or machine outlet
NAD--long spiral tube prevents liquid vapor form entering bypass |
|
|
What should you do if you tilt a vaporizer >45degrees?
|
Flush vaporizer with O2 10LPM in max setting for 5 minutes
|
|
|
What do you do if your vaporizer has been in a horizontal position for any length of time?
|
Drain liquid from vaporizer and flush vaporizer >20 min
|
|
|
What do you do if you want a continouous high conc of anesthetic?
|
Have a high FGF to stop rebreathing
|
|
|
With high FGF, inspired conc will....
|
...= the dialed setting
|
|
|
With low FGFs, there is more ______, therefore....
|
rebreathing
Therefore, exhaled gases contribute a significant portion of the inspired gases--> inspired concentration is LESS than the dialed setting (diluted) |
|
|
Increased MV= Increased _______
|
Rebreathing
|
|
|
What is special about the Tec 6 Des Vaporizer?
|
Liquid Des heated to 39 deg
Des vapor with VP of 1550 torr (2 atmos) No carrier gas enters chamber bec its high pressure Can turn up concentrations 1-18% (least potent) |
|
|
Des vaporizer is the only one that...
|
Requiers a warming up time
Alarms if low agent (<50ml) No output alarm if <20ml Can fill vaporizer while it's on |
|
|
What machine has vaporizers in agent color coded cassettes?
|
Aladin Vaporizer (Ohmeda)
Cassette can be transported in any position |
|
|
1ml liquid=
|
200 ml vapor
|
|
|
How do you figure out the mL liquid used per hour?
|
3 x FGF x volume %
|
