INTRODUCTION TO CHEMPHYSICS OF ANESTHESIA

1
INTRODUCTION TO CHEM/PHYSICS OF ANESTHESIA

• Review of Measurements
• Review of Chemistry Basics
• Review of the Basics of Physics
• Fluids
• Solubility
• Gas Laws
• Vaporization
• Acid Bases and Buffers
• Sine Waves
• Electricity

2
Mathematical Review

• What is Physics
• Review of Basic Math
• Measurement and Significant
• Calculations
• Estimation

• Accuracy and Precision
• Si
• Density
• Specific Gravity

3
Order of Operation

• Addition
• Subtraction
• Multiplication
• Division

• You need to do multiplication and division before
  addition and subtraction

4
X 12 3 x 10

• X 12 30
• X 42

5
Algebra

• Unknown
• quantity Convert equation into some form of x
• If the variable is multiplied by some number you
  need to divide both sides of the equation by that
  number
• If the variable is divided by some number you
  need to multiply both sides of the equation by
  that number
• Addition and substraction the same rule applies

6
12X 180

• X 15

7
Square Roots
8
Exponentials

• Shorthand for the number of times a quantity is
  multiplied
• Volume 1cm x 1cm x 1cm
• Volume 1 x 1 x 1 cm x cm x cm
• 1 x 1 x 1 1
• 1cm³

9
Logarithms

• Logarithms are mixed up exponents.

10
Scientific Notation

• The use of exponents for handling very large
  numbers. A number multiplied by the power of ten.
  How many places you have to move the decimal
  point so that one digit remains to the left of
  the decimal point.
• 11,000,000 1.1 x 107
• 0.00000000045 4.5 x 10 -9

11
Estiminations

• How many piano tuners are there in Chicago?

12
Graphing

• The value of x changes in a predictable way in
  response to changes in the value of some other
  variable

13
Accuracy and Precision

• Accuracy
• The agreement between experimental data and the
  true value

• Precision
• Is agreement between replicate measurement

14
It is important that the pulse oximeter gives
consistent readings

• If the readings are different every time you will
  lose confidence in the patients condition

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Si metric system

• The metric system consists of a base unit and a
  prefix multiplier
• Base unit length, mass or volume
• Prefix multipliers increase or decrease the
  size of the base unit

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Session 2

• Review of Chemistry

17
State of Matter

• Five states

18
Atomic Structure
19
molecules

• Made up of atoms of or different elements

20
Vanderwaals Forces

• Two molecules on collision course
• Closer accelerate toward one another
• Initial collision molecule adopts new straight
  course
• As temperature increases number of collisions
  increase

21
Isotopes

• Different atomic weights caused by gain or loss
  of atoms different physical properties

22
Avogadro

• Avogadro's Number, 6.022 x 1023

Equal volumes of gases at the same temperature
and pressure contain the same number of molecules
regardless of their chemical nature and physical
properties
23
Periodic table
24
Chemical bonding
25
Chemical bonding

• NaCl

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Covalent bond

• Covalent bonds form when atoms share electrons.
  Since electrons move very fast they can be
  shared, effectively filling or emptying the outer
  shells of the atoms involved in the bond. Such
  bonds are referred to as electron-sharing bonds.
  An analogy can be made to child custody the
  children are like electrons, and tend to spend
  some time with one parent and the rest of their
  time with the other parent.
• In a covalent bond, the electron clouds
  surrounding the atomic nuclei overlap.

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Covalent Bond
30

Hydrogen bonds result from the weak electrical
attraction between the positive end of one
molecule and the negative end of another.
Individually these bonds are very weak, although
taken in a large enough quantity, the result is
strong enough to hold molecules together or in a
three-dimensional shape.
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Chemical reaction

• Combustion

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Carbon Dioxide Absorber

• Reaction of CO2 in Soda Line
• CO2 H2O H2CO3
• H2CO3 2NaOH
  Na2CO3 2H2O heat
• Na2CO3 Ca(OH)2 CaCO3
  NaOH

33
Valence

• a measure of the number of chemical bonds formed
  by the atoms of a given element.
• The concept was developed in the middle of the
  nineteenth century in an attempt to rationalize
  the formulae of different chemical compounds.

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Radical
35
Radical Group of Atoms

• Hydroxyl l (-OH)
• Phosphate (PO4.2)
• Ammonium (NH4)
• Bicarbonate (HCO3)

• Sulfate (SO)
• Nitrate (NO3)
• Carbonate l (CO3)

36

• Organic Chemistry

37
Names

• Ethane 2 Carbons
• Propane 3 Carbons
• Butane 4 Carbons
• Pentane 5 Carbons
• Hexane 6 Carbons
• Heptane 7 Carbons
• Octane 8 Carbons
• nonane 9 Carbons
• Decane 10 Carbons

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The next most complex hydrocarbon structure is
called ethane

• CH3CH3

39
Alkane

• Each bond is accounted for by an individual atom
• Remove a H substance become a radical
• Methane CH4 Methy CH3
• Radicals are named by converting ANC to YL
• Methane to Methyl
• Propane to Propl

40
Complex Organic Compounds

• Branch chain alkanes (named for longest continued
  chain)
• Name, position on chain begins at either end of
  longest chain
• Primary, Secondary and tertiary are used to
  differentiate forms of the same compound
• Atom groups may be indicated by a prefix. Numbers
  denote position
• When identical groups are located on the same
  carbon the main chain number are supplied for
  each group
• Last portion of the compound name will be the
  main chain
• alkane

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Alkenes and Alkynes

• Alkenes Have a general formula C2H2

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Isomers
43
Stereoisomers

• Identical structural formula but different in
  their spatial arrangement
• Optical
• Oeometric

44
Optical Isomers

• When the groups attached to the carbon atom
  differ from one another
• Cause a bending (rotation) of light passing
  through the substances vertical axis.
• Light polarized to the right produces a dextro
  isomer, when light is polarized left the levo
  isomer is formed
• Mirror images
• Mixed racemic

45
Oeometric Isomers

• Two carbon atoms joined by a double bond

46
Class Divisions of Organic Compounds

• Alcohol

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Class Divisions of Organic Compounds

• Alcohols
• Primary
• Secondary
• Tertiary

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Class Divisions of Organic Compounds

• Halogen
• 
  
• Aldehydes
  
• 
  

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Class Divisions of Organic Compounds

• Ketone

u
50
Class Divisions of Organic Compounds

• Esters

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Class Divisions of Organic Compounds

• Amino acid

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Class Divisions of Organic Compounds

• Amine

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Class Divisions of Organic Compounds

• Amide
• Amide synthesis

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Class Divisions of Organic Compounds

• Thio Compounds

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Class Divisions of Organic Compounds

• Organic Acids (COOH)

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Class Divisions of Organic Compounds

• Quaternary Base
• Formed from Ammonium hydroxide

57
Class Divisions of Organic Compounds

• C6H6

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Class Divisions of Organic Compounds

• Ethyl ether
• Dimethyl ether
• Diethyl ether
• isoflurane

59
Class Divisions of Organic Compounds

• Polynuclear Aromatic Structure

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Session 3

• Review of Physics

61
CAUSES OF MOTION

• Newtons First Law
• Newtons Second Law
• Newtons Third Law
• Vectors
• Gravity
• Frictional Forces

62
MOTION

• SPEED
• VELOCITY
• ACCELERATION

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Reduction Valves
f
P
a
64
Reduction Valve
f
a
Low pressure
High pressure
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Resistance

• Resistance pressure drop/flow
• Pressure drop along a tube which results fluid
  flow

66
Pumps

• Heart
• Apply and learn most laws of Physic
• Flow Force

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Work

• Work
• Work done on an object is the force times the
  distance moved
• W Fs

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Energy

• Capacity for doing work
• Cannot be lost but converted

Kinetic Energy
Potential Energy
69
Law of Conservation of Energy

• Energy can neither be created or destroyed
  through it can be transformed from one form to
  another

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Power

• RATE OF DOING WORK
• Differential of work
• Similar to velocity (distance velocity)
• Units of power are watts

71
Machine

• DEVICE FOR MULTIPLYING FORCE
• Does not supply energy
• Mechanical advantage force output/force
  input

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Heat and Temperature

• Temperature is a measurement of the tendency to
  gain or loose heat
• Heat is energy which can be transferred

73
First Law of Thermodynamics
Q

U

W
Change in internal energy energy transferred to
object from a higher temp body work done on the
object
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Stress

• Force on a given area
• Stress force/area

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Thermal Expansion

• An increase in heat will cause an object to
  expand
• Expansion is constant for a given material
• Expansion is constant in all directions

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Thermometry

• Liquid expansion Thermometers
• Bimetallic Strip Thermometer
• Thermocouples
• Thermistors
• Radiation Thermometry

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HEAT

• Calorie is the unit of measurement
• Calorie is the heat required to raise 1g of water
  1o C

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Heat Capacity

• Heat required to raise the temperature of a given
  material
• HEAT Capacity Mass x Specific heat

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Specific Heat

• The amount of heat required to raise the
  temperature of 1kg of a substance by 1oC
• Specific heat of gasltltltltltspecific heat of
  corresponding liquid

80
Effects of heat

• Heat of crystallization
• Latent heat of fusion
• Latent heat of vaporization

81
Factors that affect the rate of change of heat of
an object

• Heat Capacity (inv proportional)
• Temperature gradient (dir proportional)
• Surface area (dir proportional)
• Forced convection(dir proportional)

82
Heat Transfer

• Convection 30
• Conduction 20
• Radiation 40
• Evaporation 10

83
Convection

• Heat transfer caused by the movement of a liquid
  or gas
• natural
• forced

84
Conduction

• Transfer of heat by the direct interaction of
  molecules in a hot area with molecules in a
  cooler area
• Does not involved motion of the body
• thermal conductivity of material is a measure of
  efficiency
• Rate of heat loss (wall area)(thermal
  conductivity
• wall thickness

Directly proportional to numerator factors
Inversely proportional to wall thickness
85
Radiation

• All bodies absorb or emit electromagnetic
  radiation including thermal or infrared radiation
• Stefan-Bolzman - Total emmissive power

86
Evaporization

• Heat lost through respiration

87
Body Temperature

• Average body temperature
• Core temperature 37C
• Skin temperature 34C
• Average Temp 36C
• 0.66 x core temperature 0.34 x ave skin temp
• 2/3 Core 1/3 Shell

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Session 4

• Fluids

89
Pressure

• P f/a
• P pressure
• f force
• a area
• Pressure is inversely proportional to the cross
  section of the radius

90
Pascals Principal

• When an external pressure is applied to confined
  fluid, it is transmitted unchanged to every point
  within the fluid

91
Pressure is inversely proportional to the cross
section of the radius
f
a
f
a
92
Buoyancy

• buoyancy is the upward force on an object
  produced by the surrounding liquid or gas in
  which it is fully or partially immersed, due to
  the pressure difference of the fluid between the
  top and bottom of the object.

93
Archimedes Principles

• An object immersed either totally or partially in
  a fluid feels a buoyant force equal to the weight
  of the fluid displaced

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Hydrodynamics Moving fluids

• Flow Rates
• The volume of fluid passing a particular point
  per unit time

• Velocity

The rate of change of position.
The rate of change of velocity is referred to as
acceleration
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Bernoulli

• Law states that the pressure of a fluid varies
  inversely with speed, an increase in speed
  producing a decrease in pressure (such as a drop
  in hydraulic pressure as the fluid speeds up
  flowing through a constriction in a pipe) and
  vice versa

96
Venturi Tube Flowmeter
97
Venturi cont

• The Venturi effect is the fluid pressure that
  results when an incompressible fluid flows
  through a constricted section of pipe.

98
Surface Tension

• The force per unit length acting across any line
  in the surface and tending to pull the surface
  apart across the lines
• Temperature

99
Surface Tension
Hg
H2O
t
t
t
t
gravity
gravity
100
Viscosity

• A measure of the resistance of a fluid to
  deform under shear stress. It is commonly
  perceived as "thickness", or resistance to
  pouring.

101
Laminar Flow

• When a fluid streams through a tube, the
  particles comprising the fluid

May move along lines parallel to the walls of the
tube
102
Poiseuilles Law

• Poiseulle determined that the laminar flow rate
  of an incompressible fluid along a pipe is
  proportional to the fourth power of the pipe's
  radius. To test his idea, we'll show that you
  need sixteen tubes to pass as much water as one
  tube twice their diameter.

103
Reynolds Number

• For a given liquid and tube there is a critical
  flow rate above
• which the flow will become turbulent
• Proportional to viscosity
• Inversely Proportional to density
• Inversely proportional to the radius of tube

104
Turbulence
105
Session 5

• Solubility

106
Density

• Density Mass/Volume

107

• Absolute humidity refers to the mass of water in
  a particular volume of air

108
Specific Gravity

• Specific Gravity density of substance/density
  of water

109
Diffusion

• Process by which the molecules of a substance
  transfer through a layer or area such as the
  surface of a solution
• Diffusion can still take place without a membrane
  or gas-liquid barrier
• Process of molecular intermingling
• Molecular movement and should not be confused
  with movement in bulk, for which some external
  force like gravity must apply

110
Gas diffusion
111
Solubility

• Henrys Law
• Temperature effect
• Coefficient of solubility
• Bunsen Solubility

• Ostwalds Solubility Coefficient
• Meyer Overton
• Fick
• Graham

112
Osmosis
Osmosis Pressure
Semi permeable membrane
113
Osmotic Pressure

• Inversely proportional to the volume of the
  solution
• Proportional to absolute temperature
• PV nRT

114
Solubility Applications

• Oxygen Therapy
• Oxygen therapy for abdominal distention
• Air Embolism
• Diffusion Hypoxia
• Inhalation of gas mixtures at positive pressure

115
Solubility Coefficient
Ratio of the amount of a substance present in one
phase compared with another, the two phases
being of equal volume and in
37C
1
1
Tension is often used in place of partial pressure
116
Relative Humidity

• Relative humidity is defined as the ratio of the
  partial pressure of water vapor in a gaseous
  mixture of air and water to the saturated vapor
  pressure of water at a given temperature. That
  is, a ratio of how much energy has been used to
  free water from liquid to vapor form to how much
  energy is left

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Session 6

• Gas Laws

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Gas Laws

• Boyles
• Charles
• Daltons
• Henrys

• Grahams
• Gay-Lussacs
• Ideal
• Ficks

120
BOYLES

• V/TCONSTANT
• P1V1 P2V2

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Boyles law
122
Charles Law

• V1 / T1 V2 / T2

123
Charles / Guy Lussacs

P1 / T1 P2 / T2
124
Daltons Law

• P P1 P2 P3

125
Henrys Law

• The amount of a non reacting gas which dissolves
  in liquid is directly proportional to the partial
  pressure of the gas, provided the temperature
  remains constant

126

Graham's Laws of Diffusion and Effusion
127
Ficks Law

• Fick's First Law is used in steady state
  diffusion, i.e., when the concentration within
  the diffusion volume does not change with respect
  to time (JinJout).

Where J is the diffusion flux in dimensions of
(amount of substance) length-2 time-1, mol m-2
s-1 D is the diffusion coefficient or
diffusivity in dimensions of length2 time-1,
m2 s-1 f is the concentration in dimensions of
(amount of substance) length-3, mol m-3 x is
the position length, m
128
Ideal Gas Law

• PV nRT
• P pressure
• V volume
• n Mass or number of gas molecules
• R gas constant (8.317J / mole K)
• T absolute temperature

129
Joule-Thompson Effect

• is a process in which the temperature of a real
  gas is either decreased or increased by letting
  the gas expand freely at constant enthalpy (which
  means that no heat is transferred to or from the
  gas, and no external work is extracted).

130
Adiabatic Compression

• Compression in which no heat is added to or
  subtracted from the air and the internal energy
  of the air is increased by an amount equivalent
  to the external work done on the air. The
  increase in temperature of the air during
  adiabatic compression tends to increase the
  pressure on account of the decrease in volume
  alone therefore, the pressure during adiabatic
  compression rises faster than the volume
  diminishes

131
Remembering Gas Laws
g
t
p
b
c
v
Boyles Law (Corner b) relates pressure and
volume (adjacent sides)

132
Law of La Place
Tension may be defined as the internal force
generated by a structure
La Place Law states that for cylinders, T Pr
(where T wall tension, P pressure of fluid
within the cylinder, r radius
Tension Pressure Radius
133
Tension and Pressure Relations for Soap Bubbles
P22T2/R2
P12T1/R1
P1
P2
T2
T1
P1gtP2 because T1T2
134
Tension and Pressure Relations for Surfactant
Deficient Alveoli (ARDS)
P1
P2
T1
T2
P1gtP2 because T1T2
135
La Place
136
Applications of Gas Laws
137
Session 7

• Vaporization

138
Vaporization

• Vapor pressure
• Boiling point
• Concentration of gases
• Specific heat
• Thermal conductivity

139
Heat of Fusion

• The energy required to change a gram of a
  substance from the solid to the liquid state
  without changing its temperature is commonly
  called it's "heat of fusion". This energy breaks
  down the solid bonds, but leaves a significant
  amount of energy associated with the
  intermolecular forces of the liquid state.

140
Heat of Vaporization

• The energy required to change a gram of a liquid
  into the gaseous state at the boiling point is
  called the "heat of vaporization". This energy
  breaks down the intermolecular attractive forces,
  and also must provide the energy necessary to
  expand the gas (the PDV work). For an ideal gas ,
  there is no longer any potential energy
  associated with intermolecular forces. So the
  internal energy is entirely in the molecular
  kinetic energy.
• The final energy is depicted here as being in
  translational kinetic energy, which is not
  strictly true. There is also some vibrational and
  rotational energy.

141
Saturated Vapor Pressure

• The process of evaporation in a closed container
  will proceed until there are as many molecules
  returning to the liquid as there are escaping. At
  this point the vapor is said to be saturated, and
  the pressure of that vapor (usually expressed in
  mmHg) is called the saturated vapor pressure.
  Since the molecular kinetic energy is greater at
  higher temperature, more molecules can escape the
  surface and the saturated vapor pressure is
  correspondingly higher. If the liquid is open to
  the air, then the vapor pressure is seen as a
  partial pressure along with the other
  constituents of the air. The temperature at which
  the vapor pressure is equal to the atmospheric
  pressure is called the boiling point.

142
Evaporation

• Ordinary evaporation is a surface phenomenon -
  some molecules have enough kinetic energy to
  escape. If the container is closed, an
  equilibrium is reached where an equal number of
  molecules return to the surface. The pressure of
  this equilibrium is called the saturation vapor
  pressure.
• In order to evaporate, a mass of water must
  collect the large heat of vaporization, so
  evaporation is a potent cooling mechanism.
  Evaporation heat loss is a major climatic factor
  and is crucial in the cooling of the human body

143
Evaporation vs Boiling
Ordinary evaporation is a surface phenomenon -
since the vapor pressure is low and since the
pressure inside the liquid is equal to
atmospheric pressure plus the liquid pressure,
bubbles of water vapor cannot form. But at the
boiling point, the saturated vapor pressure is
equal to atmospheric pressure, bubbles form, and
the vaporization becomes a volume phenomena.

144
Boiling Point

• The boiling point is defined as the temperature
  at which the saturated vapor pressure of a liquid
  is equal to the surrounding atmospheric pressure.
  For water, the vapor pressure reaches the
  standard sea level atmospheric pressure of 760
  mmHg at 100C. Since the vapor pressure increases
  with temperature, it follows that for pressure
  greater than 760 mmHg (e.g., in a pressure
  cooker), the boiling point is above 100C and for
  pressure less than 760 mmHg (e.g., at altitudes
  above sea level), the boiling point will be lower
  than 100C. As long as a vessel of water is
  boiling at 760 mmHg, it will remain at 100C
  until the phase change is complete. Rapidly
  boiling water is not at a higher temperature than
  slowly boiling water. The stability of the
  boiling point makes it a convenient calibration
  temperature for temperature scales.

145
Vaporization

• Vapor Pressures at 200C
• Isoflurane 239mmHg
• Enflurane 175mmHg
• Halothane 243mmHg
• Desflurane 669mmHg
• Sevofurane

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Calculating Volumes of Vapor Formed in Vaporizers

• Volume Vaporized Vp (vapor pressure)
• Total Gas Flow Patm (atmosphere
  pressure)
• 
  (Vp/760mmhg)(carrier Flow)
• volume vaporized -------------------------------
  -------
• 1-
  (Vp/760mmhg
• (239/760)(200) (.31)(200ml/min)
• VV ------------------- ----------------------
  91ml/min
• 1 - (329/760)
  (.69)

147
Generic Vaporizer

• Schematic

Total patient flow
Carrier gas
148
Humidity

• Humidity is the amount of water vapor in an air
  sample

• There are three different ways to measure
  humidity
• absolute humidity
• relative humidity,
• specific humidity.

149
Specific Humidity

• Specific Humidity is the ratio of water vapor to
  air (dry air plus water vapor) in a particular
  volume of air.

150
Session 8

• Acid Base Buffers

151
Chemical Equilibria

• Starting materials products
• Starting materials combine to give products break
  down into starting materials. These two
  processes occur simultaneously

152
Le Chatelier Principle

• Equilibrium is a good thing and nature strives to
  attain and/ or maintain equilibrium

153
changing concentration

• If you add products the equilibrium will shift
  toward reactants. If you remove products the
  equilibrium will shift towards the product.
• Hb 4O2 Hb(O2)4
• Lungs oxygen concentration is high increased
  oxygen concertration is added to the material
  equilibrium shifts towards the product (
  oxyhemoglobin) trying to undo the increased
  oxxygen
• Cells the oxygen is low the system precieves this
  as removing reactant equilibrium shift towards
  the material trying to replace the missing
  reactant oxygen
• Therefore hemoglobin loads up on oxygen in the
  lungs and dumps oxygen into the cells

154
changing temperature

• Exothermic reaction evolve energy from the system
• Endothermic reactions absorb energy from the
  system
• Therefore increase in temperature favors
  endothermic process

155
Changing volume and pressure

• Changing volume and/or pressure only impacts
  equilibrium reactions when at least one reactants
  or products is a gas ( solids and liquids are not
  compressable)
• With respect to hemoglobin when the partial
  pressure of oxygen is increased equilibrium
  shifts right ( why giving pure oxygen results in
  a greater oxygen saturation in the blood)

156
Acid and Bases

• Acid donates a hydrogen ion to a base
• Base accepts a hydrogen ion from an acid

157
Acid Base Pairs

• HCL H CL-
• The H ion is a proton
• Chloride ion has special relationship with HCL
• If the reaction ran in reverse the chloride ion
  would pick up the hydrogen ion. If the chloride
  ion took a hydrogen ion that would mean if was
  acting as a base. Therefore Chloride is the
  conjugate base of HCL and HCL is the conjugate
  acid to chloride
• They are conjugate acid-base pairs

158
Conjugate Acid and Bases
159

• acid conjugate base of
• acid
• HCL H2O
  CL H3O
• base
  
  conjugate acid of base

160
Strong acid

• When a strong acid dissolves in water it
  essentially 100 ionized. That means essentially
  all of the molecules dissociate into ions.
• The reaction is not an equilibrating process, so
  all of the starting materials are converted into
  product.
• HCL H2O H3O CL-

161
Common Strong Acids
162
Strong Bases

• Bases accept hydrogen ions the strongest possible
  base is the hydroxide ion OH
• A strong base ionizes 100 produces the OH- ion
• NaOH Na OH-

163
Strong bases
164
Weak Acids

• Weak acids are able to donate hydrogen ions to
  bases but are less determined to do so than
  strong acids
• When weak acid dissolves in water establishes
  dynamic equilibrium between molecular form and
  ionized form
• HC2H3O2 H C2H3O2-
• acetic
  acid
• in water

165
Weak Acids (notice that ions can behave as acids
as well as molecular compounds)
166
Weak bases

• Weak bases do not completely ionize in water
• When weak bases dissolve in water it establishes
  a dynamic equilibrium between the molecular form
  and the ionized form
• NH3 H2O NH4 OH-

167
Weak bases
168
Polyprotic acids

• Diprotic acid has more than one hydrogen ion to
  donate
• H2CO3 carbonic acid
• Tripotic Acid has three hydrogen ions to donate
• H3PO4 phosphoric acid

169
pH

• pH -logH

170
Buffers

• The buffer in a solution resists changes in pH
• Buffer contains contain weak acid and conjugate
  base

171
Ka

• Negative log of Ka is pKa
• The concentration of the base is greater than the
  concentration of the weak acid
• Therefore the pH is on the basic side of the pKa

172
pKa (weak acids and weak bases)

• Weak acids become more unionized as ph decreases
• pKa of a weak acid is the pH at which 50 of the
  weak acid is ionized and 50 is unionized
• pKa is different for different weak acids
• unionized
• pH 1 7.4
  8.5 14
• 
  pKa

173

• 
  ionized
• 1 3.5
  7.4 14
• pH pKa
  pH pH
• The higher the pKa of a weak acid the greater the
  amount of drug that is unionized at physiologic
  pH

174
Weak bases

• A weak base is more unionized as th ph increases
• The pKa of a weak base is the pH at which 50 of
  the weak base is in ionized and 50 ins unionized
• The pKa is different for different weak bases
• A given weak base may have any pKa however the
  pKa is constant for a given weak base

175
Weak bases

• ionized
• 1
  7.4 9.1
  14
• pH
  pH pKa
  pH
• 
  unionized
• 
  
• 1 4.5
  7.4
  14
• pH pKa
  pH
  pH

176
Session 9

• Sine wave

177
Biological Potentials

• Cell Membrane
• Hydrophobic interior
• Protein and carbohydrate exterior
• Change in ion charges
• Sodium pump

178
ECG

• Resting membrane potential is about 90mV
• Rapid loss occurs prior to conduction
• Depolorization
• Sodium ions move in
• Potassium ions move out
• Repolorization
• Opposite on transfer brings membrane back to
  negative Active transport

179
ECG cont

• 1-2 mV
• Signals pass through muscle and skin and spread
  outward
• P wave represents atrial depolorization (wave
  repolorization is hidden in the QRS)
• QRS Ventricular depolorization
• T wave ventricular repolorization
• The larger the muscle the more voltage required
  and the greater the deflection

180
EMG

• Shorter duration 5-10mS
• Repolarizes very quickly
• Do not depolorize in wave like fashion

181
EEG

• Appearance is important
• Slow low frequency cerebral hypoxia
• Anesthesia depth is indicated by a decreasing
  frequency and amplitude

182
Electrodes

• Used to pick up biological electrical potentials
  directly at the skin
• Skin surface
• Moisture
• Electrical impedance

183
Amplifiers

• Measure differences between two sources
• Resistance may vary Drift
• Range of frequencies is relative constant
  bandwidth
• Ratio of voltage to output Gain measured in
  decibels

184
Electrical potential initiators

• Defibrillators
• Nerve stimulators
• Pacemakers
• Pain stimulators
• ECT

185
Sine Waves
186
Cathode Ray Tube CRT

• Todays method of recording Biological Potentials
• An electron beam passes through two deflecting
  devices, one is deflected horizontally (x axis)
  the othee vertically (y axis). When the beam
  strikes a fluorescent screen a tracing is
  produced
• The electron beam has negligible inertia
  therefore you get a very high frequency response

187
Concept of sine waves

• Biological processes occur in a repetitive
  pattern
• A sine produces this pattern

188
Sine waves cont

• Angle A has a different value at each moment
  because the crank is rotating at a constant rate.
  D on the vertical axis shows the angle of A
  corresponding to the different times along the
  hortizontal axis

189
Wave Length

• The distance between any two corresponding points
  in successive cycles (the distance between 2
  peaks or troughts)
• Horizontal axia

190
Amplitude

• Maximum displacement of the wave from horizontal
  axis

191
Frequency

• Number of cycles which occur in 1 sec.
• Cycles per second are called Hertz (Hz)

192
Period of wave motion

• The time taken for one complete cycle to occur
• The reciprocal of frequency
• T1/f

193
Velocity of a wave in motion

• Velocity frequency x wavelength

194
waves

• Different waves have different velocities
• If the velocity is fixed-then the frequency and
  wavelength are inter-related
• The higher the frequency the shorter the wave
  length and vice versa

195
Sound Waves
196
Sound waves cont

• Sound waves of different frequencies are picked
  up by the ear as changes in pitch
• Sound waves with high frequency, short wave
  length high pitch note
• Sound wave with a low frequency, long wave length
  low pitch

197
Sound waves cont

• Sound waves are regions of higher and low
  pressure in the air and travel at a fixed
  velocity. As the object producing sound mover
  closer to you, each high pressure region becomes
  closer to the previous one and the wave length
  becomes shorter. You pick up this frequency as a
  higher pitch. Vice versa
• Doppler effect

198
Sound waves cont ultra sonic detectors

• Ultrasonic waves are beamed along an artery and
  the red blood cells reflect these high frequency
  sounds waves. The movement of the RBCs give a
  Doppler change in frequency

199
Sound waves cont

• When sound wave and other waves reach a boundary
  between two different substances, part of the
  wave is transmitted and part is reflected. Sound
  waves- the difference in the density between the
  two the two materials determine how much of the
  wave tis transmitted and how much is reflected.

200
Sound waves cont

• If an ultra sound transducer is used, the wave
  must pass between air (low density) and a solid
  structure (high density) the signal can be
  attenuated
• Gel reduces density

201
Sound waves cont

• Ultrasound waves can also be used to form images
  of body structures become the wave are reflected
  off boundaries and interfaces between substances
  of different densities.

202
Sine waves

• The addition of whole range sine waves, each with
  different frequencies, may result in quite a
  complex wave form.
• The range is important in the design and use of
  monitoring equipment.
• Wave forms can be produced by addin appropriate
  sine waves

203
Fourier Analysis

• Mathematical process of analyzing complex
  patterns into a series of simple sine wave
  patterns.
• .5Hz
• Frequency
• range
• 100Hz
• Wave patterns that have sharp spikes have high
  frequencies, smooth rounded waves have a more
  limited range of frequencies

204
Light Waves
205
Light waves cont

• Light wave motion with high frequency and short
  wave length blue
• Color spectrum
• Light wave motion with lower frequency and longer
  wavelength red

206
Light waves cont

• Visible light is a small part of the
  electromagnetic spectrum and includes
• Radio waves
• Infrared waves
• Infrared radiation
• Gamma and X-rays
• Visible light
• Visible and infrared

207
Light waves cont

• Ultrasound have a limit to the power which can be
  absorbed by tissue with harm. Absorbed power
  raises temperature
• Cavitations

208

• The relationship between absorbance and
  transmittance is illustrated in the following
  diagram

If all the light passes through a solution
without any absorption, then absorbance is zero,
and percent transmittance is 100 If all the
light is absorbed, then percent transmittance is
zero, and absorption is infinite.

209

• The amount of radiation absorbed may be measured
  in a number of ways Transmittance, T P / P0
  Transmittance, T 100 T Absorbance, A  log10
  P0 / PA  log10 1 / T A  log10
  100 / TA  2 - log10 T 

210
Section 10

• Electricity

211
Basic Principles of Electricity

• Fundamental force of nature
• Electrical force is the force between two objects
  on their charge
• Charge is a basic property of two of the
  elementary particles (protons and electrons)
• Electrical force can be attraction or repulsion
• The force is inversely proportional to the square
  of the distance between the objects

212
Basic principles cont

• Ohms Law (electrons to pass through their
  conduction band with very little effort)
• V I R
• V electromotive force
• I current
• R resistance

213
Basic principles cont

• DC electron flow is always in the same direction

214
Basic principles cont

• AC electron flow reverses direction at regular
  intervals

215
Basic principles cont

• Capacitance measure of the ability of object
  to hold charge

216
Basic principles cont

• Inductance is the magnetic field induced around
  the wire when electron flow is in the wire

217
Basic principles cont

• Impedance (Z) forces that oppose electron
  movement in an AC circuit. ( a more complicated
  form of resistance that includes capacitance and
  inductance.

218
Basic principles cont

• Series circuits current flows through each
  object one after another

219
Basic principles cont

• Parallel current divides every time it come to
  a junction different currents flow through the
  different objects

220
Basic principles cont

• Grounding
• Electrical power
• Grounded
• Ungrounded
• Electrical equipment

221
Basic principles cont ungrounded power
222
Basic principles cont grounded power
223
Basic principles cont

• Conductors

224
Basic principles cont

• Insulator a substance in which a charge cannot
  easily move

225
Basic principles cont

• Semiconductor material whose conduction charges
  as a result of an external force
• Thermistor as temp increases resistance decreases
• Photodector switch
• Diode
• Transistor

226
Basic principles cont

• Static electricity ( rubbing amber against
  material can lead to a transfer of electrons, so
  that one will have an excess of the and the other
  a deficit)

227
Basic principles cont

• Ampere (unit of current)
• electromagnetic force
• 6.24 x 10 to the 18 electrons per minute

228
Electrical Hazards in the OR

• Whenever an individual contacts an external
  source of electricity Shock is possible

229
Electrical Hazards in the OR

• Sources of electroshock
• Macroshock gt 1 mA
• Microshock lt 1 mA
• Conducting fluids
• Electrosurgery

230
Electrical Hazards in the OR Macroshock sources

• Severity depends on the amount and duration of
  current flow
• Occur when patient becomes the conduit through
  which current flows toward ground
• Isolated system in the OR provides significant
  protection from macroshock

231
Electrical Hazards in the OR Microshock sources

• Pacer wires
• Swan Ganz catheter
• CVP catheter
• Leakage
• partially ungrounded power source

232
Electrical Hazards in the OR

• Current can interfere with signal from ECG and
  other monitors
• If electrode is applied incorrectly a defective
  wire current will seek the path of least
  resistance
• Patient
• ECG or temperature probe

233
Electrical Hazards in the OR (LIM)

• Isolation power system provides an ungrounded
  electrical service for various applications
  within a hospital. These isolation power systems
  remain in operation in the event of a single
  line-to-ground fault situation. The system also
  eliminate the danger of an electric shock to
  patients who may be more susceptible to leakage
  current.

234
Electrical Hazards in the OR (LIM)
235
Electrical Hazards in the OR

• Summary
• All electrical equipment must undergo
  preventative maintenance, service and inspection
• Protect patients from contact with earth

236
Electrical Hazards in the OR summary

• Water on floor is dangerous
• Protect susceptible patients
• Uses common sense
• Be vigilant

237
Final Exam

• MAY