Gas Laws Flashcards
1
Q
What are the 3 physical states of substance?
A
Solid, liquid, gas
2
Q
In a _____ atoms/molecules are closely approximated due to lattice and greatly influences by intermolecular forces
A
Solid
3
Q
____ have volume and shape
A
Solids
4
Q
In _____ motion is limited; only vibrate in position
A
Solid (not totally immobile without kinetic energy)
5
Q
_____ are non-compressible
A
Solids
6
Q
If you add heat to a solid, it becomes a _____
A
Liquid
7
Q
In ____, molecules exert a weaker force on each other called Van der Waals forces
A
Liquids
8
Q
In _____, it allows fluid flow, sliding, and the molecules can move throughout the substance
A
Liquids
9
Q
____ takes the shape of the container, but does have volume
A
Liquids
10
Q
_____ are measured by collecting the volume in a measured cylinder
A
Liquids
11
Q
In ____ molecules have more kinetic energy
A
Liquids
12
Q
If you add heat to a liquid, it becomes a ____
A
Gas (vaporizing)
13
Q
In ____ molecules are independent of each other
A
Gases
14
Q
In ____, molecules are constantly moving, bombarding the sides of the container
A
Gases
15
Q
_____ have no definite shape or volume, filling whatever container
A
Gases
16
Q
_____ are measured by flowmeters or respirometers
A
Gases
17
Q
As ___ molecules move and impact the sides of the container, they exert force on the walls, creating pressure
A
Gas
18
Q
What is the saturated vapor pressure?
A
The pressure exerted by a vapor when, at any one temperature, an equilibrium is reached, at which the same number of molecules are vaporizing as are returning to liquid. (Partial pressure exerted by a vapor over a liquid in a closed container when equilibrium has been met between the liquid and vapor)
19
Q
What is a boiling point?
A
The temperature at which vapor pressure becomes equal to atmospheric pressure and at which all liquid changes to gas phase
20
Q
Vapor pressure and boiling points are _____ related
A
Inversely
21
Q
Vapor pressure is ______ dependent; Vapor pressure increases as _____ rises
A
Temperature; Temperature
22
Q
The lower the boiling point, the _____ the vapor pressure
A
Higher
23
Q
Is vapor pressure a function of volume, temperature, or pressure?
A
Temperature
24
Q
What is force?
A
That which changes or tends to change the state of rest or motion of an object
25
What unit is force measured by?
N (newton) (The force that will give a mass of 1 kg an acceleration of 1 m/s2)
26
What is the equation for force?
F = ma (mass times acceleration) (Newton's 2nd law)
27
Where would we encounter force in anesthesia?
Gravity, force of air through valves in the anesthesia machine, force of fluid through an IV, force of endotracheal tube on the surrounding tissue, positioning patients, etc.
28
What is pressure? What unit is it measured in?
The force applied over a surface; Measured in Pa (pascal) (the pressure of 1 newton acting over 1 square meter- N/m2)
Can also be measured in kPa and psi (pounds per square inch) (kPa = kilo pascals; usually used.) (psi = british, but may see psig (gauge))
SI for pressure is pascal, but number is too small to be manageable, so kPa is used
29
What is the formula for pressure?
P = f/a (force divided by acceleration)
30
Atm (atmospheric) pressure is equal to:
___ bar
____ kPa
_____ mmHg
_____ cmH20
___ psi
At sea level
1) 1 bar
2) 100 kPa
3) 760 mmHg
4) 1034 cmH20
5) 14.7 psi
31
1 kPa =
____ mmHg
____ cmH20
____ psi
1) 7.5 mmHg
2) 10.34 cmH20
3) 0.147 psi
32
What is absolute pressure?
Equals gauge pressure + atmospheric pressure. In most cases, gauge pressure is the important parameter. (ex: gas-cylinder pressures, art line pressures, ventilator pressures such as PIP)
33
Unless the word "absolute" is used, atmospheric pressure is _____
Ignored
34
What is Boyle's Law?
At a constant temperature, the volume of a given gas varies inversely with the absolute pressure (As pressure increases, volume decreases and vice versa) (squeezing the ambu bag raises the pressure and decreases the volume)
35
What is the formula for Boyle's Law?
P1 x V1 = P2 x V2
36
What is Charles' Law?
At a constant pressure, the volume of a given gas varies directly with the absolute temperature (As volume increases, so does temperature and vice versa) (inflatable cuff of LMA expands when places into an autoclave for sterilization)
37
What is the formula for Charles' Law?
V1/T1 = V2/T2 (Temp in K!!!)
38
What is the formula to convert Celsius to Kelvin?
T(Kelvin) = T (celsius) + 273
39
0 K = ______ C
-273
40
What is Gay Lussac's Law?
At a constant volume, the absolute pressure of a given mass of gas varies directly with the absolute temperature. (as volume increases, so does pressure and vice versa) (The lower the atm pressure, the lower the boiling point: Mt Everest has higher atm P)
41
What is the formula for Gay Lussac's Law?
P1/T1 = P2/T2
42
What is Dalton's Law of Partial Pressures?
In a mixture of gases, the pressure exerted by each gas is the same as that it would exert if it was alone in the container
43
What is the partial pressure of oxygen?
21 kPa (because air has 21% oxygen)
44
What is the partial pressure of Nitrogen?
79 kPa (because air has 79% nitrogen)
45
Partial pressure exerted by any single gas in a combination of gases is ____ proportional to its % composition of the gas mixture
Directly
46
What is the formula to find total pressure from partial pressures?
P1 + P2 + P3 = P total
47
What is Avogadro's Hypothesis?
Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules (a mole)
48
What is Avogadro's number?
6.022 x 10^23
49
One mole of any gas at STP occupies ___ liters
22.4
50
One mole of any gas at STP is equal to ___ g
44
51
STP is ___ celsius, ___ mmHG, dry (no water vapor)
0 degrees C; 760 mmHg
52
What are the 3 universal gas constants?
1) PV
2) V/T
3) P/T
53
What is the formula for the universal gas constant?
PV/T = universal gas constant (nR)
54
If the pressure is directly proportional to the number of moles in a cylinder and thus the amount of gas in the cylinder, the pressure gauge acts as a contents gauge if the cylinder contains a ____
Gas (applies to oxygen and air, but not nitrous oxide)
55
What is the Universal Gas Law or Ideal Gas Law?
Application to a cylinder of gas, V is constant, R is a constant, T is held constant; so P is directly proportional to n.
56
What is the formula for the Universal Gas Law?
PV = nRT (n is the number of moles)
57
With an oxygen cylinder, as the pressure on the gauge decreases, so does the amount of _____
Gas (moles which determine liters)
58
What is a critical temperature?
The temperature above which no amount of pressure can liquify a gas (gas can liquify at a critical temperature, but not at a temperature any higher)
59
What is a critical pressure?
The pressure to liquify a gas at its critical temperature
60
Solution is a homogenous mixture of a ____ (gas) in a ___ (liquid)
Solute; solvent
61
Solubility depends on 4 things:
1) Partial pressure of the gas
2) Temperature
3) Gas
4) Liquid
62
What is saturated solution?
Where an equilibrium will be attained where as many molecules of gas are entering the liquid as leaving the liquid
63
What is an example of a homogenous mixture?
Sugar in tea versus dirt in water; neuromuscular blocker (water soluble) versus propofol (suspension)
64
What is Henry's Law?
At a certain temperature, the amount of a given gas dissolved in a given liquid is directly proportional to the partial pressure of the gas in equilibrium with the liquid (ex: breathing air under pressure as a scuba diver causes more nitrogen into solution in tissues)
65
What is an anesthesia related example of Henry's Law?
Over-pressuring, or giving more than needed to increase amount; for example, at induction of anesthesia when a higher concentration of anesthetic than necessary for maintenance, or a loading dose, is delivered to speed uptake.
66
In Henry's Law, as temperature of liquid increases, the amount of ___ dissolved decreases
Gas
67
Solubility of a gas in a liquid is increased when _____ of the liquid decreases
Temperature
68
More inhalational agent will dissolve in the blood if the patient is ____ (Le Chatelier's)
Hypothermic (if a patient is cold at the end of an anesthetic, the inhaled anesthetic will be more soluble in the blood and cause delayed emergence)
69
What is Le Chatelier's Principle?
A change in any of the factors in determining an equilibrium causes the system to adjust or reduce or counteract the effect of the change. (solubility increases with decreasing temp)
70
What is the solubility coefficient?
The volume of gas which dissolves in one unit volume of the liquid at the temperature concerned
71
What is the partition coefficient?
The ratio of the amount of substance present in one phase compared with another (the two phases being of equal volume and in equilibrium) (stated for 37 degrees celsius unless stated otherwise)
72
What is the Blood-Gas partition coefficient?
Reflects the proportion of the anesthetic that will be absorbed in the blood versus the amount of anesthetic that will leave the blood to diffuse into tissues
73
Is the order listed for blood-gas or gas-blood ratio important?
Yes, if it is blood-gas, blood should be listed first and vice versa
74
If Desflurane has a blood-gas of 0.42 to 1, does it prefer to be in the blood or gas phase?
It prefers to be in gas phase, rather than blood phase (0.42 is less than 1)
75
Inhaled agents with low solubility (low blood/gas coefficient) causing build up in the alveoli, produce a ____ induction of anesthesia
Rapid (also has a more rapid emergence)
76
The lower the blood-gas partition coefficient, the ___ the induction
Faster
77
Low blood-gas coefficient means ___ soluble
Poorly (equilibrium between gas and blood and brain is reached rapidly)
78
Do we want our gas to build up in alveoli?
Yes, it will cause an equilibrium between gas and blood and then brain
79
What is the oil-gas partition coefficient?
The ratio of a gas present in oil versus in the gas state; indicates how efficiently a gas can access and affect the sites of action
80
The higher the oil-gas coefficient (lipid-solubility), the more ____ the anesthetic gas
Potent
81
What drug is most potent? What drug is least potent?
Most = Halothane; Least = Nitrous
82
What is diffusion?
The continual movement of molecules among each other in liquids or gases
83
Diffusion always occurs in areas of ____ concentration to areas of _____ concentration
High; low
84
Diffusion across 3 areas that n't have to be a membrane:
1) Gas-liquid barrier
2) Gas filled area
3) Membrane
(Leak, gas leaks out of mask because not good seal, leaks out of vaporizer cylinder, etc.)
85
What 5 things can affect diffusion?
1) Thickness of membrane (d) (density)
2) Size of molecule (MW) (molecular weight)
3) Surface area of membrane (A)
4) Solubility of gas (s)
5) Pressure gradient (P1 - P2 or delta P)
86
Diffusion is ____ proportional to pressure gradient, surface area and solubility of the gas; and ______ proportional to the thickness of the membrane and size of the molecule
Directly; Indirectly
(Bigger gradient = easier to diffuse, bigger SA = easier to diffuse, increased solubility = easier to diffuse; thicker membrane = harder to diffuse, bigger molecule = harder to diffuse)
87
What is Fick's Law?
The rate of diffusion of a substance across a unit area is proportional to the concentration gradient (Overpressuring for induction or increasing FiO2 to increase PaO2)
)explains concentration effect, second gas effect, diffusion hypoxia, expanded air-filled spaces with nitrous)
88
What is Graham's Law?
The rate of diffusion of a gas is inversely proportional to the square root of its molecular weight (The larger the size, the slower the rate of diffusion)
89
What is the second gas effect with Nitrous Oxide?
Nitrous has a low solubility, and is taken up in large volumes, and accelerates the rate of rise of the alveolar concentration of the 2nd gas. (Diffuses and makes more room for second gas; such as Sevo) (explained by Fick's Law)
90
What is diffusion hypoxia caused by Nitrous Oxide?
It is low in soluibility and has a rapid uptake and elimination. it is eliminated so rapidly that it dilutes the alveolar concentration causing the PaO2 to drop. (At end of case, nitrous wants out of blood so bad, it goes into alveoli so fast it can overwhelm and make patient hypoxic) The fix for this is to administer 100% gas (explained by Fick's Law)
91
What is movement into air-filled cavities by Nitrous Oxide?
The blood-gas coefficient is 0.47, which is 34 times greater than nitrogen at 0.014. Thus, nitrous can leave the blood to enter an air-filled cavity 34 times faster than nitrogen can leave the cavity to enter the blood. If there is a compliant wall, the volume of gas expands (pneumothorax, intestinal gas, etc.) If a noncompliant wall such in the middle ear, the ear drum or graft can burst. (explained by Fick's law)
92
What is cohesion in fluids?
Internal attractive forces between like molecules trying to stick together in the smallest shape possible (liquid pulling on itself and sticks to self) (mercury)
93
What is adhesion in fluids?
Attractive forces between unlike molecules trying to stick to something different (water in a glass, concaves, wants to stick to something else)
94
What is surface tension?
Cohesive forces at the surface of a liquid that tend to keep liquid in the most compact form (Alveoli and surfactant) (Surface tension of liquid in alveoli could cause it to collapse. The surfactant reduces the surface tension and prevents collapse when alveoli come close together during expiration; when surfactant is absent, alveoli collapse can occur, as in premature neonates.
95
Does heating increase or lower surface tension?
Lowers
96
What is the formula for pressure in liquids?
P = hdw (height of column x density weight of liquid) (pressure tubing: art line, etc) (pressure is equal to force per unit area. the force in a liquid is from the column of liquid of a specific density and height above the point of measurement- from the weight of the liquid column. Under static conditions in aa liquid column, the pressure is the same in all directions at any given point. Also,, in a closed system, any change in pressure is equally transmitted to all parts of the system.)
97
In Manometers: Density of H2O is equal to what?
1 gm/cc
98
In Manometers: Density og Hg is equal to what?
13.6 gm/cc
99
Compare Hg to H2o density. 7.5 mm of Hg is equal to how many cm of H2O?
10.2
100
How do you convert cm H2O to mm Hg?
0.74 x
101
How do you convert mm Hg to cm H2O?
1.36 x
102
What is flow?
The quantity of a fluid passing aa point in a given time
103
What is the equation for flow?
F = Q/t (Q = quantity; t = time) (P1-P2)
104
What are the two types of flow?
Laminar and Turbulent
105
What is laminar flow?
Fluid movement in smooth layers with no turbulence or eddies (usually moves in smooth straight channel at low rates of flow)
106
Flow is greatest in the ________; as it comes closer to the wall of the channel, it becomes _________
Faster; slower
107
Flow will always flow in the direction of ______ resistance
Least (ex: respiratory tract where air moves mostly lamina, but changes to turbulent during speaking, coughing, or deep breathing when velocity is increased)
108
What is turbulent flow?
Flow is no longer smooth, but with swirls, eddies
109
Laminar flow changes to turbulent flow when ______ ______ is reached, _______ is changed, ________ is abruptly changes, or _____ is obstructed. _______ is increased.
1) Critical Velocity
2) Direction
3) Diameter
4) Flow
5) Resistance
110
Energy lost in turbulent flow- requires ______ pressure gradient.
Greater
111
Is turbulent the most efficient flow? Why or why not?
No, increased resistance equals decreased flow.
112
What four things can effect resistance in flow?
1) Diameter of the channel (r) (ex: 16 G vs 20 G IV)
2) Length of the channel (L) (ex: length of IV catheter)
3) Nature of the flow: laminar vs. turbulent (laminar is better)
4) Viscosity of the fluid (n) (ex: diluting PRBC with fliud so it flows better)
113
What is viscosity?
The frictional forces between layers within a fluid; cohesive forces which weaken as temperature increases. Viscosity of a fluid is influences by temperature (increase temp, decrease viscosity; decrease temp, increase viscosity) (crystalloid IV fluids have lower viscosity than blood. In the clinical setting, the viscosity of blood is influenced by the hematocrit, patient age (increases with age), smokers (increased), and can be lowered by low molecular wt dextran)
114
The factors that effect flow can be examined in an equation that is a derivative of the ________-_________ equation.
Hagen-Poiseulle
115
What is the Hagen-Poiseuille equation derivative?
Resistance = 8nL/(3.14)r^4
(n is viscosity which is directly proportional to resistance)
(L is the length of the channel which is directly proportional to resistance)
(r is the radius of the channel which is inversely proportional to the resistance to the fourth power)
116
In the Hagen-Poiseuille equation derivative, which factor has the most effect on resistance?
Radius, because it is to the 4th power (If you double the radius of the channel, the resistance to flow decreases 16x)
117
What is an application to the radius effecting flow and resistance?
Flow through different sized IV catheters or ETTs, flow out of syringes with different sized needles, mucous in ETT. (phys application: muscular work increases demand for blood flow while the heat generated slightly decreases blood viscosity; making it flow more easily)
118
Radius is especially important in what population?
Peds (airway is smaller, so even smaller with edema)
119
What is the equation for the derivative of Poiseuille's law that looks at flow rate in relation to resistance and the pressure gradient if you have an ideal fluid and no turbulence?
P1 - P2 = Resistance x Flow
or
Flow = P1 - P2/8nL/(3.14)r^4
(r^4 still on bottom, so can change flow dramatically)
(Once turbulence occurs, Poiseuille's law cannot be used to predict resistance to flow. To maintain flow rates, the pressure gradient must increase or the turbulence must be removed)
120
What is the Bernouilli Effect?
Given a channel with a narrowing which then increases, the pressure measured along the channel is lowest at the narrowest point, often below atmospheric. (If open up narrow spot, it would entrain air because pressure outside is higher than inside. Can pull from outside) (channel of flow becomes narrow; narrow portion speeds up; pressure will decrease)
121
Narrowing causes _______ velocity, thus _______ kinetic energy. To maintain unchanged sum of energy, the potential energy must ________.
1) Increased
2) Increased
3) Decreased
122
Fluid contains two forms of energy. What are they?
1) Potential energy associated with pressure
2) Kinetic energy associated with its flow
(Energy can be neither created nor destroyed, and the sum of energy must remain unchanged)
123
If an opening was located at the narrowing where the pressure is lower than atmospheric, _____ could occur.
Entrainment (this type of system is called the venturi system. It is also used with nebulized treatments. Another type of entrainment is jet entrainment where oxygen moving at high speed picks up air into flow to reduce oxygen concentration)
124
What is Laplace's Law?
The relationship of wall tension, pressure, and radius of cylinders (vessels) and spheres (ventricles and alveoli)
125
What is the equation for Laplace's Law?
Cylinders: T = Pr
Spheres: 2T = Pr
126
Aneurysm in aorta- in aneurysm with greater radius, wall tension ______ (direct relationship of tension to wall radius)
Increases (P = T/r)
(As radius increases, the greater chance of rupture. Increased pressure can damage walls and go in between aorta, creating balloon effect)
(Normal aorta: 100 mm Hg (P) x 2 cm (r) = T)
(Aneurysm: 100 mm H (P) x 4. cm (r) = T x 2)
(Surfactant lowers surface tension in alveoli and prevents the effects of Laplace's Law)
127
What is heat?
The kinetic energy of molecules of substance
128
What is a Calorie (cal)?
The energy to increase temperature of one gram of H2O 1 degree celsius
129
What is 1 kcal?
1 kcal = C = 4184 joules = energy to increase temperature of 1 kg H2O 1 degree celsius
130
Why does the body shiver?
Body is trying to produce enough energy to heat itself
131
What is temperature?
The parameter used to describe the amount of heat possessed
132
What is the conversion formula for F to C?
Tc = 5/9(Tf) - 32
133
What is the conversion formula for C to F?
Tf = 9/5(Tc) + 32
134
What is the conversion formula for C to K?
Tk = Tc + 273
135
What is Kelvin?
It is a temperature that is necessary for calculations in gas laws. (The kelvin unit is the same as the Celsius unit, so at times these are interchanged)
(Don't have to convert temp in Boyle's Law)
(Notice that kelvin is not recorded in degrees. 0 K is the absolute zero because at this temperature, all atomic motion ceases)
136
What is triple point?
The temperature at which water, ice, and water vapor are all in equilibrium. This is 0 degrees C or 273.15 K
137
What is the first law of thermodynamics?
Heat is a form of energy and can be converted to other forms of energy, but neither created nor destroyed
138
What is the second law of thermodynamics?
Heat always flows from warmer to cooler. There must exist a difference in temperature and the two things must be in contact. (Hand cold when holding cold drink; hand lost heat to can)
139
What are the 4 methods of heat transfer?
1) Conduction
2) Radiation
3) Convection
4) Evaporation
140
What is conduction?
Heat movement through a substance by the transfer of kinetic energy from molecule to molecule. (roasting marshmallows with wood sticks, versus metal sticks)
141
Metals have ____ conductivity; air has _____ conductivity
Good; poor
142
Is conduction a real factor in the heat loss from an anesthetized patient?
No; the patient is in contact with only the foam pad, which is an excellent thermal insulator (lose about 2%)
143
What is radiation?
Heat transferred from warmer to cooler objects by emission and absorption of energy radiated in varying wavelengths. Objects do not have to be touching. (gas logs; can feel heat coming off without touching them; same with oven)
144
Which form of heat loss accounts for the largest percentage of normal heat loss from the body?
Radiation
145
What percentage of heat loss in the anesthetized patient is lost from radiation?
40%
146
How can heat loss from radiation be minimized?
Surrounding the object/body with warm objects. (it can be accelerated by surrounding the body with cool objects) (the difference of temperature between the two objects determines the rate of heat transfer)
147
What is convection?
Heat transfer occurs by moving fluid (liquid or gas)
(Blood: if not warmed it would pick up heat as it passes through tissues, so body temp would decrease; want to warm it)
148
Air adjacent to body is warmed, it expands and moves ______, and carries heat ______
Away; away
149
What percentage of heat loss in the anesthetized patient is lost from convection?
32%
150
What are examples of convection?
Wind chill and convection air current. Air over hot beach sand, warm rises, moves out over water where it cools and moves closer to waters surface and is pushed back to sandy beach. This becomes a cycle.
151
What is the easiest way to reduce heat loss?
Covering or insulating the skin surface. (whether using cotton blankets, surgical drapes, or plastic sheeting, a single layer to trap air reduces heat loss about 30%)
152
Another important factor about heat loss is the:
Amount of skin surface covered
(Misconception that a large percentage of heat is lost through head. In neonate and infant this is true because their heads account for such a high percentage of the body surface area. But in the adult patient, the amount of surface covered is the important factor.)
153
Convection also occurs in the respiratory tract. What would be the prevention?
Warm inspired gasses
154
What is evaporation?
The loss of latent heat of vaporization of moisture on the skin's surface
155
What is latent heat of vaporization?
The heat required to change liquid into vapor (liquid decreases in temp because heat has to come from somewhere)
If evaporation occurs, the remaining liquid loses heat (decreased temp = decreased vaporization)
156
Evaporation accounts for what percentage of heat loss?
28%
157
What two factors influence evaporation?
1) Difference in vapor pressure between skin surface and surrounding air (amount of heat lost can be increased ten times by sweating)
2) The amount of surface exposed
158
Evaporation occurs in surgical ______ and the ______ tract
Surgical wounds and respiratory tract
159
What should you do to reduce heat loss from evaporation?
Wipe perspiration off or it can take some of the patient's heat
160
What is specific heat capcity?
The amount of heat required to raise the temperature of 1 kg of a substance by 1 kelvin
161
What is the standard for specific heat capacity?
Water (1 cal/g/degree C = 1 kcal/kg/degree C)
162
1 cal = _____ joules
4.18
163
Temperature changes more gradually with materials with a ____ specific heat than those with a ___ specific heat
High; Low
164
The materials chosen for vaporizers need to have a ______ specific heat capacity so that they cool off slower
Higher
165
We also need to know the specific heat of the volatile anesthetic agent, so we know how much heat to apply to _______ its temperature to the point of vaporization.
Increase
166
What is heat capacity?
The amount of heat required to raise the temperature of an object by 1 kelvin.
167
How is heat capacity calculated?
By multiplying the mass of the object by the specific heat capacity
Ex: 70 kg patient trying to increase his temp from 36 to 37 degrees C, how many minutes of shivering would it take?
Specific heat capacities can be approximated to. mean of 3.5 kJ/kg/degree C. So for a 70 kg patient it would be 245 kJ/degree C
SO the additional heat production from shivering is 240 W or 240 x 60 joules/min. This is 14.4 kJ/min. If 245 kJ are needed to increase temp 1 degree C, then it will take 245/14.4 minutes or 17 minutes of shivering
(She says we won't have to calculate)
168
Basal heat production is ___ W/m^2 (average man 80W)
50 W/m^2
169
Shivering can increase heat production up to _ times (320 W)
4 times (also increases the amount of O2 myocardium needs; not good with someone with CAD (potential for ischemia))
170
What is specific latent heat?
The energy required to convert 1 kg of a substance from one phase to another at a given temperature (J/kg)
171
What is latent heat of fusion?
The heat required to change a solid to a liquid
172
What is latent heat of vaporization?
Heat required to change a substance from a liquid to a gas at a constant temperature
173
Application of latent heat of vaporization: When a N2O cylinder is allowed to empty rapidly, the cylinder becomes very cold and the water vapor from the surrounding air freezes on the cylinder. What effect is this?
Joule-Thompson effect
174
An additional application of latent heat of vaporization is in the vaporizer of the ______ _______
Anesthesia machine
175
When volatile inhalation agents change from liquid to vapor, it requires heat, causing the remaining liquid and the walls of the vaporizer to _____ (_____ heat). If this is not counteracted, the ______ temperature would make the liquid less volatile, and the amount of agent vaporized would decrease.
Cool; lose heat
176
Vaporizers have different means to _______
Compensate
177
Nitrous cylinder cooling is also called the ________-_________ effect
Joule-Thompson effect (joule is cool)
178
What is the atomic structure of radiation?
Protons, neutrons & electrons
(X-rays & lasers)
179
Atoms are comprised of protons, neutrons, and electrons. The element is determined by the number of ________. The number of ________ determines the isotope and the stability of the nucleus.
Protons; Neutrons
180
What is an unstable isotope?
- Beta particle (electron) may be emitted
- The nucleus may attract and capture an electron
- Alpha particle is lost consisting of two protons and two neutrons
- The nucleus may split into several parts (unstable)
181
After the isotope has decayed, it is common that it will emit an _________ wave or ________ ray
Electromagnetic wave or gamma ray (radiation)
182
What is an ionizing type of electromagnetic radiation?
- Releases energy by removing electrons from atoms in tissues
- Creating ions that are very chemically reactive and very hazardous
- Includes X-rays and gamma rays released by radioactive isotopes
(Harmful if not intended target)
183
What is a nonionizing type of electromagnetic radiation?
- Discharges its energy without creating ions or removing electrons from atoms in tissues
- Includes infrared radiation, visible light, ultraviolet radiation as utilized with lasers
184
What does LASER stand for?
Light amplification by stimulated emission of radiation
185
How do you protect yourself against ionizing radiation?
Distance, time & shielding
186
What is the best form of protection against ionizing radiation?
Distance
187
How much distance should you have to protect yourself from ionizing radiation?
At least 3 feet away; 6 feet of air is the equivalent of 9 inches of concrete or 2.5 mm lead
(0.25 to 0.5 mm lead sheeting blocks most scattered radiation)
(The intensity of scattered radiation is inversely proportional to the square of the distance from the source)
188
How much time should you have to protect yourself from ionizing radiation?
Minimize time around radiation
189
What type of shielding should you use to protect yourself from ionizing radiation?
Use barriers, such as lead aprons
190
There is increasing use of radiation in the OR. ____________, which is the greatest source of exposure, is used by orthopedic surgeons, neurosurgeons, urologists, general and vascular surgeons. Exposure is due to x-rays scattered by both patient and other surfaces (it bounces off surfaces just like light reflects)
Fluoroscopy
191
A lead apron with ____ mm lead thickness equivalence should be sufficient for most fluoroscopic procedures. For high workload, a wrap around lead apron with __ mm lead equivalence that overlaps on the front and provides 0.25 + 0.25 = 0.5 mm lead equivalence on the front and __ mm on the back would be ideal.
0.35 mm
0.25 mm
0.25 mm
192
What is the maximum yearly occupational exposure to ionizing radiation allowed?
No more than 5 rem or 5000 mrem
193
One chest x-ray is about how much mrem?
25 mrem
194
Using fluoroscopy during a routine procedure, the exposure may be greater than _______ mrem
8000 mrem
195
Recommendations by the National Council of Radiation Protection are < ____ mrem/week or <__ rem/year
<100 mrem/week
<5 rem/year
196
What does rem stand for?
Roentgen-equivalent-man or the dose of ionizing radiation with the same biologic tissue effect as 1 rad of x-rays
197
Radiation absorbed dose is a measure of an absorbed dose equal to ____ ergs/g of any absorber
100ergs/g
198
During fluoroscopy for cardiac angiography, the dose may be > __________ mrem
75,000
199
During CANT TALK RIGHT NOW the exposure of personnel is ____, because the radiation is very highly focused
Low
200
Does MRI produce ionizing radiation?
No; just remove metal; if implants or pacemakers, they can overheat or disable
201
Should radiation personnel and others exposed such as OR personnel be monitored for radiation exposure?
Yes
202
Monitoring shows that one person rarely absorbs more than ___ mrem/year.
50 mrem/year
203
Actively dividing cells are affected by radiation, making tumors and ______ susceptible.
Fetuses
204
During pregnancy, the maximum exposure should be < ____ mrem. (The fetus is susceptible before the pregnancy is known)
<500 mrem
205
How should you protect yourself against nonionizing radiation?
- Eyewear must have lenses that filter the specific wavelength of the laser in use
- Instruments should be non-reflective
Distance does not help
206
Reflected radiation injuries include burns to the ____ and ______, destruction of the macula or optic nerve, and cataract formation.
Cornea & Retina
(the patient's eyes should be covered with moistened gauze pads. Any exposed skin should be covered with a moistened towel)
207
CO2 lasers emit energy with a wavelength of ____ um (far infrared blocked by clear lenses)
10.6 micrometers
208
YAG produce energy at ___ um (near infrared require special lens)
1.06 micrometers
209
KTP lasers emit energy at ____ um
532
210
Other burn prevention involves the ETT, oxygen and nitrous oxide in use. How?
Use wrapped tube and decrease your percentage of oxygen to 30%; discontinue use of nitrous
211
What is a filter mask?
Intake of the plume, the vapor and cellular debris, may present significant risk
(Most surgical masks don't filter out particles that small. Regular filter masks filter 3 um particles. In studies of lab animals, it was shown that if all particles >0.1 um were scavenged, there was no lung damage. If all particles >0.5 um were scavenged, pulmonary damage was found in lab animals. Under experimental conditions, both HPV (which is found in plantar warts and genital condylomata) and HIV were detected in the plume. At children's a common procedure is treating papillomas with lasers under direct laryngoscopy.)
212
Debris size ranges from ___ to ___ um (micrometers)
0.1 to 0.8 um
213
Intact DNA of HPV and HIV proviral DNA found in ______
Plume
214
___ lasers produce the most smoke due to vaporization of tissue.
CO2 lasers
215
____ lasers produce the least smoke
YAG
(the best practice is to use an efficient smoke evacuator)
