Physics and Chemistry Flashcards
vapor pressures for VAA’s are at what temperature?
20 degrees C
Whats the Vapor Pressure? Sevoflurane
170 mmHg (7-sevo0
Whats the Vapor Pressure? Enflurane
172 mmHg
Whats the Vapor Pressure? Isoflurane
240 mmHg
Whats the Vapor Pressure? Halothane
244 mmHg
Whats the Vapor Pressure? Desflurane
669 mmHg (des 6)
is the vapor pressure a function of volume, temperature, or pressure?
temperature
the pressure at which the gaseous state is in equilibrium with either the liquid or solid state, or with both is known as what?
the saturated vapor pressure (SVP)
Volatile agent in a flask is an ex of whose law
daltons
if Iso is added to a flask of Oxygen, what is the percent of oxygen and percent of iso In the flask above the liquid?
the VP of iso is 240 mmHg the Partial pressure of oxygen is 760 mmHg
The partial pressure of O2 after Iso is added is 520 mmHg (760-240=520mmHg)
%O2 = (520mmHg / 760 mmHg) x 100% = 68.4% O2
%iso = (240mmHg / 760 mmHg) x 100% = 31.6% iso
Formula is %gas = P gas / P total
Adding VAA to the wrong vaporizer:
what are the mnemonics?
HLH- high VP in Low VP = High concentration delivered
LHL- Low VP in High VP = Low concentration delivered
If halothane is added to Enflurane or servo what concentration will be delivered?
hal- 244 enf 172 Sevo 170
HLH
High concentration delivered
If halothane is added to iso vaporizer what concentration would be delivered?
Halothane 244 Iso 240
about the same
If ENF or Sevo added to Halothane or Iso vaporizer what concentration would be delivered?
ENF 172 sevo 170 Hal 244 iso 240
LHL
Low concentration
Desflurane vaporizer is heated to what temp
39 degrees C
why is des vaporizer heated
it is heated to almost 2 atmospheric pressures, this high pressure drives des to the gas outlet where it’s diluted
unit conversions:
1 mmHg = ____ cm H2O
1.36 cmH2O
unit conversions:
1 atm = ____ mmHg = ___psi = ___kPa = ___ bar
1 atm = 760mmHg = 14.7 psi = 101 kPa = 1 bar
1 psi = ____ mmHg
54mmHg
what are gauges that measure HIGH pressures (cylinder pressures)
bourdon gauges
do Bourdon pressure gauges measure th pressure relative to atmospheric pressure or the absolute pressue
the pressure relative to atmospheric pressure
when the Bourdon gauge reads 0 the pressure inside the cylinder is equal to what?
atmospheric pressure
what is the formula for the law of laplace? cylindrically- shaped structures
T=P x r
T= wall tension
P= pressure
r = radius
Law of laplace:
states that as the structure expands (radius increases) the tension (force) in the wall of the structure does what?
Increases
Law of laplace:
application
a cappillary will withstand a pressure of 100mmHg for better than a vein, b/c the capillary has a tiny radius compared to a vein, so the tension in the wall of the capillary is extraordinarily smaller than that in the vein
Law of laplace:
Application
an aortic aneurysm is much more likely to rupture than a normal segment of the aorta b/c the radius is much larger, thereby increasing the tension on the wall to the “breaking point”
who’s law states that the greater the tension in ventricular wall at end diastole, the greater the stroke volume
frank-starling law
law of laplace: Spherically shaped
what is an ex of a spherically shaped structure
alveoli
law of laplace: Spherically shaped
what is the formula
T= P x r / 2
or 2T= P x r
law of laplace: Spherically shaped
facts
tension is independent of radius for all spheres where there is a liquid-air interface (soap bubble. the pressure inside the bubble will change with its size. the smaller the radius of the bubble the greater the pressure inside the bubble.
how does the law of laplace: Spherically shaped apply to alveoli? with ARDS
b/c pressure in the smaller alveoli is higher than th larger alveoli.
the law of laplace explains why smaller alveoli empty into larger alveoli causing atelectasis in pts w/ ARDS
how does the law of laplace: Spherically shaped apply to alveoli? with Normal lungs
for alveoli with surfactant , tension increases w/ increases in radius, b/c alveolar wall tension increases in proportion to increases in radius, the pressure within the alveolus does not change. the law of laplace explains why small alveoli do not empty into larger alveoli
Flow of liquids:
Laminar (streamlined) flow is described mathematically by whose law
hagen-Poiseulle’s law
Flow of liquids:
with laminar flow where is flow the fastest
Middle
Flow of liquids:
w/ laminar flow, what is the flow like against the wall
zero flow (think of why plaque builds up in arteries)
what is the formula for flow
Q= pie x radius^4 x pressure gradient / 8 x viscosity x length
Look at page 306 to see pic
Flow of liquids:
doubling the radius increases flow by how much
16 times
Flow of liquids:
what factor alters flow the most?
radius
what is the property of a fluid that determines flow when the flow in laminar
viscosity
Flow of liquid:
is it directly or inversely proportional to radius
directly- doubling the radius increases flow by 16 times
Flow of liquid:
is it directly or inversely proportional to hydrostatic pressure gradient?
directly- rising the IV pole increases hydrostatic pressure in the fluid delivered to the pt via gravity.
Flow of liquid:
is it directly or inversely proportional to viscosity
Inversely- thicker blood slower flow
Flow of liquid:
is it directly or inversely proportional to length
inversely- reducing the needle length increases flow.
Flow of liquid:
what is the formula for resistance
R= change in pressure / flow
what are 4 things that increase turbulent flow
Faster flow
Bigger tubes
Density increased
Viscosity decreased
resistance to flow (increases or decreases) when flow becomes turbulant
increases
what is the name the predicts when flow through a cylinder tube changes from laminar to turbulent
Reynolds number
when the Reynolds number exceeds _____ - _____ flow changes from laminar to turbuilant
1500-2,000 (2,000 is the magical number)
when flow in turbulent what determines flow?
density
-this is why we use helium (its density is lower and and better for obstructions)
who’s principle does the venturi effect full under
Bernoulli’s principle
when fluid flows through a constricted region of a tube (venturi tube) the velocity of the flow does what?
increases (think of a narrowing of a stream - it gets faster)
when fluid flows through a constricted region of a tube (venturi tube) the velocity of the flow INCREASES and the lateral pressure (pressure exerted by the fluid on the walls of the tube) does what?
Decreases (think thats why you can park a boat on a deck int he river the walls have less pressure)
when fluid flows through a constricted region of a tube (venturi tube) the velocity of the flow INCREASES and the lateral pressure (pressure exerted by the fluid on the walls of the tube) DECREASES what effect is this termed
Bernoulli effect
