I. Matter and Energy:
Matter occupies space and has mass. It cannot be created or destroyed and it
exists in 3 states.
1. States of matter
a. Solids – have definite shape and volume.
b. Liquids – have definite volume but are variable in shape
c. Gas – has no definite shape or volume.
2. Specific volume
3. Types of Energy
- kinetic energy actual movement or work being done
- potential energy is amt. of energy stored within a substance ready to
produce some work.
4. Molecular structure and weight. All matter can be broken down into
elemental units, which are atoms. Each element has an atomic # and weight
relating to the # of protons in the nucleus of the atom. There are also an equal
# of neutrons here and a specific # of electrons circling the core. The atomic
weight of the atom is the "mass" of the atom and can be calculated
using the total # of protons and neutrons. There are isotopes which share
characteristics and # of protons but may have one or two less or more neutrons.
5. Atomic # and electron distribution – as above. The electrons
circle the nucleus of an atom. The # of them depends on the substance and can be
related to its position on the periodic table. Each horizontal row designates a
new shell while each vertical row adds an electron to the atom as one travels
left to right. The molecules on the far right are inert gases with full shells
of electrons thus have no need to combine with other molecules. Their shells are
full and they are happy! The theory of octet is what this phenomenon is
about. The most unstable of elements are the 1st row on the left. The
stability increases as one moves across to the right. The # of electrons that
are able to react are called valence electrons. Anything with a valence electron
of 3 or less is considered to be a metal and are highly reactive. IE. Lithium
has an atomic # of 3. Its 1st shell has 2 electrons and is full but
its second shell has only 1. It will donate that 1 electron to another element
to keep its 1st shell full and happy. Potassium has atomic # of 19. #
of electrons is 2 in the 1st shell, 8 in the 2nd and 3rd
shells and only 1 in the 4th shell. Carbon can go either way has +/-
4 electrons. This whole area can also be referred to as the Bohr model.
6. Classification and reactivity of elements – reactivity will be
dependent on the amt. of valence electrons available in the outer shell.
7. Types of bonding – Chemical bonds can be an ionic bond where the
electron in the outer shell will leave the shell and go to another molecule.
Sodium would give off one electron and chloride would take one. The result is a
very stable bond. In covalent bonds the electrons are shared so that the
electrons are circulating and sharing between the molecules. This bond can be
polar (with a + and – end) or nonpolar (with and equal distance btw electrons
or centers of the atoms. There can also be univalent bonding where the + valence
# means they’ll donate electrons and anything that accepts electrons is know
as a – valence.
8. Molecular motion and phases of matter – Cohesion is motion of
matter. Solids move a little, liquids move more and gases move a great deal.
Molecular motion increases as energy is added. Molecules exhibit a force of
mutual attraction – closer they are to each other the greater the force is.
This force btw like molecules is cohesion. The strongest state of cohesion will
be in solid form. Cohesive force diminishes as molecules become further apart.
Adhesion is a similar concept but with unlike molecules and it is the force that
keeps the unlike substances together.
9. Temperature – can be measured in Fahrenheit, celsius or Kelvin.
Kelvin is used in the ideal gas laws. To convert F to C: 9/5 x C + 32 = F K = C
C to F: F – 32 x 5/9 = C
0 degrees K is the temp at which energy stops moving. It is very cold! The
definition of temp is the way of measuring the average of the kinetic energy
of molecules of the substance. Molecules that move fast will have higher temps
while slow moving molecules will have lower temps.
11. Methods of physiologic heat loss: van’t Hoff’s Law
I. Gas laws
- Gas – the gas laws work for ideal gases only but there aren’t any,
they don’t exist other that theoretically. The molecules are far apart and
have no attraction for each other. Rare gases exist in labs; these molecules
are still far apart but have negligible cohesiveness. Real gases behave like
ideal gases. They have cohesive and adhesive forces present. With a high
temp. and a low pressure these will elicit the behavior of ideal gases but
still have cohesive and adhesive forces.
- Pressure – the force exerted on the container walls. Ie. A cylinder
will have many collisions of molecules against each other and this will
increase the pressure. Oxygen bang in to each other and this will increase
the pressure in the cylinder as more collisions occur. Barometric
pressure, the measure of the atmosphere or a BP cuff will actually measure
the pressure by using a column of mercury (Hg). If you reduce the volume
of gas or reduce the container size, these will increase the pressure of
the gas if you maintained a constant temp and atm.
- Mean free path
- Van der Waal’s forces – the mutual attractions brought about by
electrical charges. These need to be overcome to be able to separate
molecules or changing the shape of molecules. Forces occur when shape and
pattern of electrical charges are aligned so one end is relatively + and
one end is +. Must overcome these forces to change from a liquid to a
2. Temperature conversions as above
3. Standard temp and pressure – 0 degrees C and 760mmHg (atm pres. at sea
4. Boyle’s Law – deals with pres. and vol. with temp as constant. At
constant temp, pres. and vol. will vary inversely. This applies only to ideal
gases. P1 x V1 = P2 x V2
Ie. Squeezing the ambu bag. Raise the press in the bag, the volume will go
out of the bag. As the pressure in the lungs increase the volume will go into
the lungs. A spontaneously breathing person breathes by the press in the lungs
decreasing and the volume increases. This law expresses compressibility of
gases at constant temps.
5. Charles’ Law – Volume and temp at constant pressure. Volume is
directly proportional to absolute temp at constant pressure. V1/T1 =V2/T2
ie. Laryngeal mask airway uses a cuff. When it is steam sterilized is must
have the air removed from the cuff first since it will expand when heated.
6. Gay Lussac’s Law – pressure is directly proportional to absolute temp
(in Kelvin) if volume is constant. P1/T1 = P2/T2
7. Avagadro’s Law – one mole of any gas at same temp has same # of
molecules. Equal volumes of gases under same pressures and temps contain the
same # of molecules
Avogadro’s Number is 6.02 x 10 to the 23rd molecules.
8. Gram molecular weight and volume - GMW is expressed in grams. One mole of
any substance = 1 gm. Of molecular weight. Gram molecular volume is GMW divided
by wt per liter. Ie. O2 has 32 grams per mole. 32/1.429gm/liter = 22.4L
9. Ideal Gas Law – is a combination of Charles, Gay Lussac’s and Boyle’s
PV = nRT
10. Definitions -
Diffusion and Humidification
- Density - is mass divided by volume. Gases are always expressed in liters.
- Specific gravity –
- Baricity - deals with the density of a specific solution. Ie. The density
of a local anesthetic solution divided by the density of the CSF. CSF is
1.001 –1.005 gm/l at 37 degrees C.
Isobaric – will have the same baricity of CSF and will stay where you
Hypobaric – will be lighter than CSF and will travel upward
Hyperbaric – will be heavier than CSF and will travel downward or sink
Graham’s Law - When gases are liberated they dispense quickly in order to
fill the space they are occupying. The goal is to achieve equal pressures in
both places. This especially applies to anesthetic gases. The rate of
diffusion of one gas compared to another varies inversely with the square root
of molecular weight. A large gas will take more time to diffuse than a smaller
gas. Ie. CO2 is offloaded into the lungs. CO2 is 4-6x faster than O2 in the
lungs due to its molecular weight.
Dalton’s Law of Partial Pressures – the total pressure exerted is made
up of the sums of all gases in a container. P1 + P2 + P3 =
Fick’s Law of Diffusion: gases and non-gases - the diffusion rate is
proportional to differences in partial pressures. A gas always diffuses from
an area of high pressure to an area of low pressure.
Pressure gradient – the diffusion rate is directly proportional to partial
pressure gradient, the area of membrane available to diffuse through and the
solubility of gases to the membrane. CO2 is larger but it diffuses 20x faster
than O2 since it is more soluble than O2. P1 – P2 x area x
solubility/membrane thickness square root of molecular weight.
Humidity and Humidification: Absolute and Relative. Humidity refers to
presence of water molecules in the gaseous state in a mixture of gases. The
gaseous water molecules are considered vapors at temp. below the critical
temp. of water expressed as relative and absolute. Absolute is water content
of gas expressed as wt. Of water per volume of gas. Units are mg of h2o
/liters of air. Relative humidity is the ratio of absolute humidity to the
saturated humidity at a given temp. (Saturated humidity is related to the
maximum vapor capacity.) Humidification in vapor pressure is important to
avoid dryness being inhaled. Amt. of evaporation of liquid water is directly
proportional to its temp. If ambient temp is less than water temp is then
water vapor will recondense back in to water and "rainout" will
occur like the glugging of water collecting in the vent tubing. The temp of
the room is cooler so the vapor in the tube will fall below 37 and condense
again. This has led to the development of filters or traps to utilize their
own exhaled vapors to humidify the air. HME’s are the name.
Ie. Atmos of sea level thus P =760mmHg. O2 has 21% of 760 and N has 79% The
total of the two will equal 760. Ie. If a flask has 100% of O2 and isofluorane
is added, what will the concentration of O2 be in the flask. Would need to
know the vapor pressure of inhalation agents.
Hypothermia – Increases consumption of O2 and can decrease production of
CO2. For every one degree of C change there is a decrease or increase of 7.9%
in O2 consumption. Oxyhemoglobin dissociation curve comes in here. If
hypothermic will cause a shift to the left where hemoglobin will hold O2 and
not release it to the tissues thus tissue hypoxia develops. There can also be
a shift in the pH of .01 per decrease in temp by 1 degrees C. This will
decrease the amt. of anesthesia necessary. Blood viscosity will increase 2-3%
per change in C. If temp is cool and you check an H&H will show
hemoconcentration and be higher than the actual value. There can also be
clotting problems with hypothermia, tend to bleed. The other thing to watch
for is shivering since this increase O2 consumption 400-500%.
Humidification is important due to the heat loss experienced in the OR from
1.radiation, 2.convection, 3.conduction, and 4.evaporation.
Water vapor in the alveoli is always constant and is = to 47mmHg. Will have
to subtract this pressure when figuring out aA gradients and pO2’s.
- Pressure and tension, liquefaction and solubility
- Pressure units and conversions – Use the metric system of grams for
weight, liter for volume and meter for length. Standard temp is 0 degrees C.
and stand pressure is 760mmHg
- Cylinders and Bourdon gauges - The bourdon gauge is a way of measuring
high pressures relative to the atmospheric pressure say in a cylinder.
- Joule-Thompson Effect – This has to do with why cylinders cool to allow
gas to escape. If they didn’t cool then the heat from the escaping gas
would cause an explosion. The gas is released slowly and it will expand. If
this occurs in a small closed space then heat is emitted in the space. If
gas is released in a large space there will be a cooling effect. Stated in
Hall’s piece this effect is seen if gas is allowed to expand in a vacuum;
then energy is lost in overcoming intermolecular attraction and the gas
cools. An example is seen by opening an O2 tank into a room, the valve will
be cool and water vapor could condense near this.
- Adiabatic compression and expansion – volume changes without heat loss
or gain from the environment. All gases cool during expansion and heat
during compression. This is true for a closed system only and this
conversion to expand or compress is reversible or else it would be the
Joules-Thompson effect. The heat of the cylinder will change according to
- Law of LaPlace – tension is defined as an internal force generated by a
structure. For cylinders T =Pr where r is the radius. T is the wall tension
and P is the pressure of fluid in the cylinder. A sphere would be T=Pr/2.
Spheres are alveoli.
- Critical temperature and pressure – Gases will liquefy if sufficient
pressure is applied and temp. is below a critical value. If a gas is above
its critical temp you cannot liquefy if even by varying pressures. O2 is
compressed gas. Could not maintain the liquid O2 since its crit temp is –119degrees
C. Nitrous oxide is liquid compressed cylinder since its crit temp is 36.5.
You will always have a reading on the gauge of 745 until the liquid N2O is
used up and then the gauge will cut in half while there is just compressed
gas left but that will be used very quickly and the tank will now read
empty. Must always measure the tanks to check for fullness.
- Raoult’s Law
- Henry’s Law
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