Physical Science Exam 2 PDF

Lecture 1: Gas Laws 1. Describe properties of gas 2. Detail Boyle’s/Charles/Gay-Lussac’s Law 3. Identify Avagadro’s Number 4. Detail Universal Gas Law 5. Discuss Van Der Waal’s Equation 6. Detail Adiabatic Changes...

Lecture 1: Gas Laws 1. Describe properties of gas 2. Detail Boyle’s/Charles/Gay-Lussac’s Law 3. Identify Avagadro’s Number 4. Detail Universal Gas Law 5. Discuss Van Der Waal’s Equation 6. Detail Adiabatic Changes 7. Detail Dalton’s Law · Properties of Gas o Molecules move freely of one another; in constant random motion o Attractive forces btwn molecules are less than their kinetic energy o Molecules exert no force on each other, unless they collide o Collision of molecules with each other or walls of container DO NOT decrease energy of system o Temperature of gas is dependent on average of kinetic energy · Boyle’s Law o Temperature constant o P & V = Inverse relationship o P1 x V1 = P2 x V2 o Hand-bag ventilation § Volume decreases but pressure increases in lungs = expansion of lungs · Charles’ Law o Pressure constant o T & V = Direct relationship o T1/V1 = T2/V2 o Gas expands when heated · Gay-Lussac’s Law o Volume constant o T &P = Direct relationship o T1/P1 = T2/P2 o Decreased temp = decreased kinetic energy = pressure reduced · Avogadro’s Number o Describes relationship btwn amount of gas and volume of gas o The number of molecules in 1 mole of gas § 1 mole = 6.023 x 1023 § 1 mole = 22.4 L § 1 mole = MW · Universal Gas Law  o Gas preforms ideally o PV = nrT o r = 0.0821L/atm · van der Waal’s Equation o Accounts for: § Volume of actual molecules § Intermolecular forces o Example: surfactant · Adiabatic Changes o Doesn’t allow time for equilibrium with the environment § Concentration effect: decrease area = intense effect (heating effect) · Compressing gas quickly will intensify kinetic energy and increase temperature § Dilution effect: increase area = less intensity (cooling effect) · Rapid expansion of gas lessens kinetic energy and decreases energy · Dalton’s Law o Total partial pressure of gas mixture is sum of individual partial pressures o 760 mmHg = P (total) @sea level § At different altitude; same percentage of gas but different # of molecules o P (total) = P1 + P2 + P3 + P4 Lecture 2: Intro into Physics 1. List Units of Measurement 2. Describe Force 3. Describe Pressure 4. Identify types of Energy 5. Describe Work & how it is measured List Units of Measurement o Mass- grams (g) o Length- meters (m) o Volume- liters (L) o Time- seconds (sec) Newtons Laws o 3rd Law of Reciprocal Action: every action has a equal and opposite reaction Describe Force o The amount of energy required to change and object from a state of rest to a state of motion. o F = mass (m) x acceleration (a) o Quantified; measured in Newtons § Energy needed to move 1 kg 1 meter o Gravity is a force/ attraction to mass § Large molecules attract other molecules § Hydrostatic pressure is altered depending on gravity and how distal the location is from the heart Describe Pressure o Pressure is the amount of force applied per unit area o Measure in Pascal (Pa) and Kilopascal (kPa) o Bourdon Guage gauge pressure § Directly measures pressure § Used on compress gas cylinders § Pressure is applied inside hallow tube causes expansion of metal coil and corresponding movement on pointer o Absolute pressure = atmospheric pressure + gauge pressure o Gauge pressure = absolute pressure - atmospheric pressure Identify types of Energy o Measured in Joules § Potential Energy: capacity to do work; stored energy to be converted into WORK § Kinetic Energy: exertion of force  § PE and KE in equilibrium o KE and Work are one in the same o Law of Conservation: energy can not be destroyed or create only transferred/converted Describe Work & how it is measured o Force x Distance = Work o KE and Work are one in the same Lecture 3: Law of Laplace 1. Detail Laplace’s Law & how it relates to: Cylinders & Spheres 2. Describe Pascal’s Principle 3. Describe components of Surface Tension 4. Describe surfactant effects Detail Laplace’s Law & how it relates to: o Relationship of fluids to tension based on factors of pressure and radius o Tension is a stress force exerted over a given area measured in newtons o Pressure follows gradient § Small radius higher pressure § Larger radius less pressure o Cylinders: Pressure is constant § Fluid pathways are dependent on balance between internal pressure and wall tension to maintain patency § Change in tension based on radius (aneurysm has same pressure but more tension) o Spheres § Tension increases with pressure and radius § In the heart, to decrease tension hypertrophy Describe Pascal’s Principle o Pressure applied to a confined fluid is transmitted unchanged through out the entire system o Fluid acts in a constant matter Describe components of Surface Tension o Surface tension = wall tension in alveolus o Cumulative effect of intermolecular forces within a substance against the unbalanced forces at a fluid interface Describe surfactant effects o Secreted by alveolar cells = surfactant is the equalizer (Van Der Waals Forces) o Long chain phospholipids: hydrophilic head imbed between water molecules to break surface tension o Amount of surfactant stays the same § Concentration differs § Constant pressure = radius decrease -> tension decrease Lecture 4: Fluid Dynamics 1. Describe various fluid mechanics 2. Detail Poiseuille’s Law 3. Detail Reynold’s Number 4. Discuss Laminar vs Turbulent Flow 5. Detail Bernoulli’s Principle 6. Discuss Venturi Effect Describe various fluid mechanics o Fluids are susceptible to pressure and gravity § Fluids are liquids and gasses § Dynamics of fluids are defined by response to stress · Change in response to stress or succumb to strain o Perpendicular stress § Liquids resist compression § Gasses become compressed and expandable o Tangential stress § Friction is resistance to flow from surface interaction § Viscosity is the inherent property of fluid that resist flow § Friction proportional to Viscosity o Types of flow § Laminar: most predictable · Less tangential stress at center of flow with 2X velocity · More stress on bottom and outside = flow decrease § Transitional: most flow in body § Turbulent Detail Poiseuille’s Law o Flow exponentially proportional to radius- larger bore IV for rapid infusion o Flow directly proportional to pressure gradient- pressure bag for IV fluids o Flow indirectly proportional to viscosity- anemia or polycythemia o Flow indirectly proportional to length – IV vs CL or Trach vs ETT Detail Reynold’s Number o Index that uses Poiseuille Law and fluid density to determine whether a given flow will be laminar or turbulent o Flow directly proportional to: § Velocity § Diameter § Density o Flow indirectly proportional to: Viscosity o Laminar flow 2000 Discuss Laminar vs Turbulent Flow o Laminar: most predictable § Less tangential stress at center of flow with 2X velocity § More stress on bottom and outside = flow decrease § Viscosity is important determiner o Turbulent § Irregular swirls and eddies § Occur at high velocities, sharp bends, angles and irregularities § Turbulent flow increases resistance § Density is a important determiner o Critical flow is the point at which laminar flow become turbulent Detail Bernoulli’s Principle o As flow passes through a narrowing in a tube, the velocity of that flow increases with a corresponding decrease in pressure at the area of narrowing o Velocity and pressure exist in an inverse relationship; Velocity takes away KE from pressure (Law of Conservation) Discuss Venturi Effect o Opening at the narrowing space pulls in extra air o Jet ventilation Lecture 5: Gas Analysis 1. Demonstrate an understanding of various types of oxygen, CO2 and gas analysis 2. Compare/contrast various methods of analyzing gases 3. Understand the components of the Beer-Lambert Law and applications within anesthesia practice 4. Analyze capnographs and associated disorders or malfunctions Demonstrate an understanding of various types of oxygen, CO2 and gas analysis o O2 Analysis: ❖ Electro-Galvanic Cell (fuel cells) Sensor: Oxygen passes through a semipermeable membrane -> O2 then dissolves into an electrolyte solution (potassium hydroxide) -> at the cathode (noble metal), oxygen molecules are reduced to hydroxyl ions -> then, the hydroxyl ions oxidize at the anode (lead or zinc) Electrical potential between the anode and cathode is measure via a Voltmeter ❖ Polarographic Electrode (Clark Electrode) Voltage source connected to cathode and anode electrodes which are immersed in an electrolyte (KCl) solution A polarizing voltage is applied -> oxygen is reduced to hydroxyl ions at the cathode -> oxidation occurs at the anode No passive consumption Current flows is proportional to the partial pressure of O2 ❖ Paramagnetic Oxygen Analyzer O2 has 2 electrons in unpaired orbits which makes it paramagnetic Dual-channel tubing: a sample of O2 passes through one channel and a reference gas through another -> rapidly altering electromagnetic fields creates pressure gradient changes which can be measured across a transducer The pressure difference is directly proportional to the concentration different between the samples Accurate and rapid measurements Newest versions no longer require calibration ❖ Fluorescence-Quenching Electron chemically or electrically excited to a higher energy level -> excited electron releases a light photon O2 absorbs photons which prevents this energy from being emitted as light -> O2 concentration can be analyzed by determining the amount of emitted photons Directly proportional to O2 concentration o CO2 Analysis ❖ Severinghaus PCO2 electrode  pH sensitive glass electrode is immersed in a bicarbonate solution with a semipermeable membrane covering the cell surface CO2 diffuses into the cell and reacts with water -> producing carbonic acid -> voltmeter measures electrical charge created by H ion concentration Current measured is proportional to CO2 concentration ❖ Colorimetric Sensor Utilizes the fluorescence Quenching principle: CO2 dissolves into a solution -> CO2 alters pH of the solution by liberating H ions -> pH-sensitive dye is activated -> fluorescent properties of the dye change (color change occurs) Hydrophobic filter prevents moisture contamination Detects CO2 but not the concentration o Gas Analysis: Mass spectrometry, infrared analysis, raman scattering analysis ❖ Mass Spectrometry: Basic Components: Ionizer mass analyzer Detector A sample is ionized and passed through a curved tube in a magnetic field -> The ionized gas molecules become deflected by the magnetic/electric field -> Ions produce electrical currents at the collectors which can be processed o Inferred Analysis: every gas absorbs radiation at a distinct wavelength ❖ Infrared radiation beam emitted (via heated radiator) -> IR beam filtered -> IR beam passes through gas sample -> Detector receives IR and converts to electrical signal to be processed ❖ Detector usually consists of temperature regulated solid-state material, flexible wall diaphragm, & a crystal § Spectrophotometric: can measure all gas except O2 § Collision broadening: overlap in gas measurements · Compare/contrast various methods of analyzing gases o Inferred Analysis § Pros · Accurate · Real time analysis · Multiple gas analysis · Portable · Newer models can detect mixtures of [multiple] volatile anesthetics § Cons · Oxygen, nitrogen, helium not measured · Gases may have overlapping absorption bands  · Anesthetic gas measurement interference by water vapor (asymmetric) Understand the components of the Beer-Lambert Law and applications within anesthesia practice ❖ Absorption of electromagnetic wave measurements are based on the Beer-Lambert Law Absorption is determined by the thickness and absorbing properties of the substance Analyze capnographs and associated disorders or malfunctions ❖ Capnography Waveform analysis Phase 0 Inspiratory phase Phase 1 Exhalation of Dead space Minimal to no CO2 Phase II: upper airway Mixture of alveolar and dead space gas Expired CO2 is from the upper airways Phase III: alveoli Alveolar plateau Corresponds to alveolar-pCO2 *Phase IV: alveolar PaCO2 End-tidal CO2 typically measured at this point Alpha Angle Between phase 2 and 3 Phase of transition to exhalation of only alveolar air Alterations signify expiratory airflow obstruction Beta angle Between phases 3 and 4 Phase of transition to inspiration Alterations in etiologies or mechanical issues of rebreathing ❖ Waveform Interpretation Normal: CO2 mmHg: 35-40; 25 mm/s Prolonged expiratory upstroke: asthma bronchospasm, COPD, partially obstructed ETT/circuit Curare Cleft: over-breathing vent Elevated baseline: incompetent expiratory valve, exhausted CO2 absorbent, insufficient gas flow Lecture 6: Pulse Ox 1. Describe the calculation of oxygen carrying capacity 2. Describe the components of the Beer-Lambert Law and applications within anesthesia practice 3. Detail the mechanics of pulse oximetry 4. Analyze advantages, disadvantages and causes of inaccuracies with pulse oximetry 5. Detail the principles of cerebral oximetry Describe the calculation of oxygen carrying capacity o Bound oxygen o Hgb is separate so blood loss with decrease pulse ox Oxyhemoglobin dissociation curve Describe the components of the Beer-Lambert Law and applications within anesthesia practice o Light transmitted through and is picked up on the others side. o Light is absorbed and less is picked up on other side. Detail the mechanics of pulse oximetry o Pulse oximeter probe contains two light-emitting diodes (LED) which are activated in alternating sequence § One in the red band- deoxyhemaglobin § One in the near infrared band- oxyhemaglobin o A photosensor detects the amount of Incident Light for each band o Absorption ratios of the red/infrared bands is compared and calculated Light absorbance at both wavelengths is then divided by the absorbance of light from extraneous tissue Analyze advantages, disadvantages and causes of inaccuracies with pulse oximetry o Advantages § Non-invasive § Easy to apply § Continuous monitoring § Earlier detection of desaturation: § SpO2 70% = PaO2 40mmHg cyanosis § Inexpensive o Disadvantage § Prone to artifact § Delayed measurements 30-60 seconds § Inaccurate at SpO2 values below 70% § Rare risk of burns in poor perfusion states o Inaccuracies § False high pulse ox: pt will be struggling to breath · Carboxyhemoglobin  · Methemoglobin § Dyes cause an underestimation of SpO2: · Methylene Blue · Indigo Carmine · Indocyanine Green § Other sources of error: · Ambient light · Deep skin pigmentation/Scar tissue · Electrosurgery decreases SpO2 readings · Motion Artifact · Fingernail polish - underestimates SpO2 Detail the principles of cerebral oximetry o Looks at scattering and reflection of radiation § Highly unpredictable § Sample has 75% venous and 25% arterial o Beer-lamberts Law doesn’t apply; must be modified Lecture 7: Electricity 1. Detail Ohm’s Law 2. Detail mechanisms of electrical currents & grounding 3. Describe the Line item Monitor & its function 4. Discuss OR electrical risks Detail Ohm’s Law o Relationship between current, volage, resistance o V=IxR o Current (I): amount of flow of electrical charge o Voltage (V): electrical (potential) gradient; electrostatic potential that pushes the charge o Resistance (R): Obstruction to flow of electricity; energy required to push electrons through a material Detail mechanisms of electrical currents & grounding o Current types § Direct current: maintains the same polarity at all times so that flow is maintained in one direction · Batteries § Alternating current: polarity direction is revered periodically · Everything else o Typical electrical circuit § Hot (+) and neutral (-) lead connect to a device to create a circuit for a flow of energy § Ground lead (3 prongs) connects to the chassis of the device to return leaked energy to the Earth for dissipation § Types of circuits · Ground system · Ungrounded system o No physical contact from power company into OR o Isolation Transformer utilizes electromagnetic induction to provide galvanic isolation § In an UNGROUNDED system- there is not contact with the electrical company · Isolation transformer: magnets send energy to each other (wireless charging) · No HOT or NEUTRAL lead; just Line 1 and Line 2 Describe the Line item Monitor & its function o Line Item Monitor (LIM) § Measure resistance which is created by leakage and unintentional grounding of lines  § Measures ohms but machine is calibrated display mA § Issues: · Faulty equipment causes leakage which activates LIM alarm and “grounds” the circuit · A “grounded” provider handles faulty equipment while it is active § Alerts to an issue with a plugged in item § Alerts to the potential for a shock Discuss OR electrical risks o Risk in OR -> “wet procedure location”; surrounded by electricity and equipment/wires o Macroshock: large amount of current conducted through the patients skin and other tissues § >20 mA = MAX let go contraction; contraction maintained § >100 mA = threshold for VFib § >2 A = Asystole § 10 uA = max allowable leakage current from hospital equipment o Electrical injury: degree of injury are determined by § Amount of current § Type of current § Current pathway (Voltage) § Resistant encountered § Duration of contact § AC more dangerous than DC due to muscle tetany § Skin burns can appear mild but internal tissue and organs can be severely damaged § The diffusion of current in the body tends to go in multiple directions (injury is unpredictable) § Decreased skin resistance allows for deeper burns that are more likely to involve internal structures o Microshock: smaller current directly affecting a target tissue (heart) § 100 uA = V fib § Current density = current/ tissue surface area ·Electrosurgery o Operates at a frequency of 500k – 100k Hz o Monopolar: requires a pad; high current density generates heat at local tissue ; energy passes through patient to dispersive pas and is returned to ESU § Avoid placement on Bony prominences, near implants/prosthesis, hairy areas, scarred/discolored tissue, or poorly perfused areas o Bipolar: energy goes between forceps; current goes between tissue; no grounding pad needed; Lower voltage Lecture 8: Lasers 1. Describe the basic mechanisms of lasers 2. Discuss the intrinsic risks and dangers of lasers 3. Describe the types of lasers, their uses and specific considerations 4. Evaluate various anesthesia techniques and interventions necessary when lasers are in use in the OR 5. Detail fire risks and evaluate emergency precautions and treatments · Describe the basic mechanisms of lasers o Visible wavelengths we can see o Infared wavelengths we cant see o Wavelengths are inversely proportional to frequency § Short wavelength = high frequency § Long wavelength = low frequency o Components of a laser: § Energy source § BREWSTER ANGLE: windows with 2 mirrors in the laser · Determines directionality o Laser light has a concentrated beam § Resonant chamber (laser medium) § Electrodes x2 (anode and cathode) ·Discuss the intrinsic risks and dangers of lasers o Protective eyewear is recommended for all personnel § Reflected radiation is as hazardous as Direct radiation § Laser beams do NOT decay = distance from source has negligible safety effects · Describe the types of lasers, their uses and specific considerations o Carbon Dioxide Laser § Superficial penetration § 10 K wavelength: longer wavelength mean lower frequency and lower energy § Commonly used in ENT surgery and in some neurosurgeries § Not visible § Far infrared wavelength § Not fiberoptic transmissible o Ng- YAG § Penetrates deeper · Photons poorly absorbed by water § 1K wavelength: shorter wavelength means higher frequency and higher energy § Useful in ENT surgery · Distal airway surgery · Better coagulation · Drawback: delayed postoperative swelling  § Not visible § Near-infrared wavelength ·Evaluate various anesthesia techniques and interventions necessary when lasers are in use in the OR o OR Staff: § Laser in stand-by mode when not in use § Secondary light beam used to assist aiming § Monitor location of instruments and flammable materials § Laser safety goggles § Clear communication § Plan of action & designated crisis roles o Patient: § Laser safety goggles § EtO2