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138 Cards in this Set
- Front
- Back
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What is not included in Ohm's law?
Farad Voltage Current Couloumb Resistance |
Farad
Coulomb |
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How do magnetic fields cause problems for patients?
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ultramagnetic induction, ultramagnetic coupling
All magnetic fields can produce electric fields, and all electric fields can produce magnetic fields |
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What precautions must be taken when performing GA for an MRI procedure?
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No metal
implantable devices must be checked |
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What precautions should you take for laser surgery on the airway?
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Double cuff tube (laser tube)
inflate cuffs with saline tinted with dye (methylene blue) saline soak pads on eyes No nitrous lowest oxygen concentration |
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What color is a CO2 laser?
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colorless
(infrared): you dont see they use a red laser with it that doesnt cause any damage |
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What should be your immediate response to a ETT fire in the OR?
What should you do next? |
First pull it out
Lavage, reestablish airway, turn off gas ABG,oxygenation steroids, antibiotics |
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Light is coherent
All the waves are in phase: that is why it is so intense and goes so far |
Laser
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Parallel beam
Doesnt spread out and is of consistent frequency of light Single frequency |
Laser
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Very light blue flame
relatively low temp hot enough to burn hard to see these flames |
"Cool" flames
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Mixture in which all the combustible vapor and oxidizing agent are consumed
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Stoichiometric mixture
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What is a lean mixture?
What is a rich mixture? |
Lean: too much oxidizer
Rich: too much fuel vapor |
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What oxidizing agents do you have in the OR?
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Nitrous (can burn without any oxygen present)
Oxygen Air |
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What 3 components are necessary to have a fire?
Also known as a fire triangle |
Something that can burn
oxidizing agent (supply of O2) heat source |
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What is the function of the reservoir bag in an anesthesia circuit?
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1)Provides a source of gas to meet peak inspiratory demand (50L/min)
2) reservoir bag 3)Provides receptacle for pt's exhaled gas and FGF 4)Provides some protection for overpressure in the breathing circuit 5)APL valve: pops off excess pressure whenever valve setting is exceeded |
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The mathematical processs of analysing complexwave patterns into a series of simpler sine wave patterns is called? This concept helps in understanding the patterns of biological electrical signals
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Fourier analysis
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What was Ayre's T-piece?
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3 limb system:
fresh gas inflow pt reservoir/outflow |
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What pressures do you see on the "line" when supply pressure is normal for Oxygen, nitrous, air?
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40-50
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What pressures do you see when cylinders are full: oxygen, nitrous, air?
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oxygen: 2000
air:2000 nitrous: 745 |
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What are the US standard colors for gas cylinders:
oxygen,CO2,nitrous,air,He? |
oxygen- green
CO2-grey Nitrous-blue air- yellow He-orange |
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What is the testing procedure for high pressure gas cylinders?
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Hydrostatic pressure testing every 5 yrs
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How can anesthetic breakdown be prevented?
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higher flows> 2L
avoid absorbent dryness use absorbent like Amsorb |
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What are some of the reaction products of anesthetic breakdown by absorbent?
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-Compound A- Sevo
-Formaldehyde- Sevo -CO- (Des > Enflurane > Iso,Sevo) -Phosgene (trichloroethylene) |
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What is the final chemically bound form of CO2?
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Binding of calcium carbonate
Amsorb eliminates sodium and potassium hydroxide |
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Describe the chemical reaction by which CO2 is absorbed?
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Dissolves in the water, reacts with the calcium hydroxide becomes calcium carbonate which dissipates in granules. Granules ay have sodium hydroxide/potassium hydroxide to increase rate of absorption. Eventually CO2 is all transferred to the calcium hydroxide.
sodium hydroxide regenerates |
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Describe the uses of capnography in the OR?
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1)Determining of adequacy of ventilation
2)Obstruction (emboli-ETCO2 drops) 3)Shape of ETCO2: slopes up ( bronchospasm, asthma) 4)Early warning of MH: sudden increase in ETCO2 5)Depth of anesthesia:40-50(adequately anesthetized) ETCO2 low: pt not deep enough ETCO2 high: pt is too deep 6)Adequacy of CO2 absorption(doesnt fall back to baseline: retaining CO2/cannister change needed) |
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What is the gas sampling rate for a sidestream monitor?
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200cc/min
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What is the relationship b/w ETCO2 and core temp?
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Core temp goes down, ETCO2 goes down
Core temp goes up, ETCO2 goes up |
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What is the relationship b/w ETCO2 and ventilation if your ETCO2 goes from 40-80 & alveolar ventilation is at 5L/min?
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Halve it: 5L goes to 2.5L
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If your ETCO2 goes from 40 to 20, alveolar ventilation is 5L/min, how much more is your alveolar ventilation?
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Double it to 10
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What is relationship b/w ETCO2 and ventilation?
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ETCO2 is more sensitive to decreases in ventilation than increases.
More sensitive to hypoventilation |
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PO2 at which 50% is Hgb bound to oxygen
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P50
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Defines the position of any given oxyhemoglobin dissociative curve
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P50
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What happens to the P50 for dissociative curve if it shifts to the R?
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(acidotic)sends the P50 up ( P50 will be at a higher P02)
remember normal curve P50= 26 |
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Absorption equal to 660nm & 940nm and pulls SpO2 towards 85%?
Doesnt carry oxygen benzocaine spray prilocaine LA sulfonamides |
MetHb
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What effect does an altitude of 10,000 ft have on pulse ox?
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pulse ox will be 90%
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What effect does an altitude of 5000ft have on your pulse ox?
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pulse ox will be 95%
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What effects does CO2 have on your dissociation curve?
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R shift:want to be able to unload oxygen at the capillary level where the tissues are slightly acidotic from metab.
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Why does Deoxygenated hgb look so dark?
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absorbs the red light
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Why does carboxyhemoglobin bllod and oxygenated blood look so red?
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reflects the red light
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What effects does CO have on pulse ox reading?
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Does not distinguish b/w carboxyhemoglobin and oxygenated hemoglobin
EX: 3 pack/day smoker: 15% Hgb bound up with CO: pulse ox reads 95% |
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tachycardia,HTN,arrythmias(PVC's, irritability type) dark blood
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Mild hypoxemia
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Hypotension, bradycardia not corrected goes to asystole
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Severe hypoxemia
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agonal type breathing?
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spontaneously breathing: severe hypoxemia
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Aline is half the size, not sharp,interference?
excessive blunting of wave form resulting from restriction to transmission pressure reads low bent cath, cath tip against vessel wall clot |
overdamped
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Resonance frequency of wave
pressure reading is high ex: excessive length of pressure tubing |
Underdamping
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Describe all the pressures that can be monitored with a PA cath?
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RAP
PAP LVEDP RA |
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What is the effect on CO if both mean art BP and SVR double?
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BP= CO x SVR
stays the same |
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what is the effect if CO is constant and SVR doubles?
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CO constant, double the BP
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Describe the application of Ohm's Law to the circulation
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V = I x R
BP= CO x SVR |
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How do you calculate the mean art Bp?
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diastolic x 2 + SBP/ 3
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ETCO2
Chest rise minute ventilation TV |
indicators to assess the adequacy of ventilation of a pt under GA
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What is the lowest setting for the O2 alarm?
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25%
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What monitoring of the pt under GA is not required?
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Temp
(what is required is the ability to measure temp) |
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Big transformer
reduces risk of shock |
Isolated Power supply
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Grounding equipment
line isolator transformer Meters in OR (LIM) two prong-doubling insulated old days (grounded straps inside shoe) prevent shock |
Techniques used to prevent electrical shock to personnel & pt's in OR
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Goes through the skin, shock that you can feel
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Macroshock
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small amt of current
into a transvenous pacemaker could be lethal pt has to have an indwelling line, wire/cath going to the heart |
Microshock
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What factors are necessary to produce a burn from electrical current?
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High current density flow and a smaller area the current flows through
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Checked by biomed, can tell whether are any faults/ if equipment is operating properly
little bit less electricity coming out |
Leakage current
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Doesnt ordinarily flow in a circuit
builds up and discharges when those surfaces are close enough together One object can have an excess of electrons and another a deficit |
Static electricity
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Low frequency current
coming out of the walls 60cycles/sec more dangerous |
AC
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Prevent from electrical shock
less current coming out of device then coming in protects you usually located in wet areas |
Ground fault interruptor
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It protects the equipment
pops open and allows you to reset do not have to replace fuse |
Circuit breaker
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melts and protects the equipment from overload
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Fuse
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Safety factor that prevents electrical shock
if there is a fault the current will go tot he ground and protects you |
Electrical ground
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What does V=IxR mean?
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voltage = current x resistance
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How much shift is from one wave to another
usually expressed as degrees |
"Phase" relationship of two sine waves
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Phase shift b/w two sine waves start at same time and add up
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summation
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Phase shift b/w two is 180 degrees out of phase
flat line |
cancellation
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repetitive, complex, large number of sine waves go into the construction
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Biological waveforms
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Need high frequency sine waves to make these
(ECG)? |
very sharp waveforms
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Time delay b/w transmission and return of signal in an ultrasound tell you what about the tissue
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depth of tissue
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The quality of the signal that comes back in an ultrasound tells you what?
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Type of tissue that is more resorbant, reflective
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Frequency shift that occurs when the source of the wave moves towards or away from the observer
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Doppler effect
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The higher the frequency, ? wavelength
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shorter the wavelength
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The lower the frequency the ? wavelength
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longer the wavelength
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very high frequency sound; travels well through body tissues
detects movement of Rbc CO detector |
ultrasound
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What drug given IV will increase ETCO2?
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Bicarb
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You see a sudden rise in ETCO2 during a vascular case. What may have happened?
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Lactic acidosis
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You see a sudden rise in ETCO2 during an orthopedic case?
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Tourniquet was let down
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You are doing an OMS case and notice a marked flattening of CO2 rise on the capnogram?
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Obstruction
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You get the message "line block" during the case. What does it mean?
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Condensation in tubing
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A 30yr female having pelvic surgery suddenly has a fall in ETCO2 to 20?
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emboli
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A 7yr child has a rapid rise in ETCO2 to 70?
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MH
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A 70yr male during a routine hernia repair exhibits a rapid fall off of the capnogram waveform to a flat line. What are the next two things that you check
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EKG, pulse
extubation |
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Simplest repetitive waveform that you can have
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Sine wave
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Repetitive with complex waveforms. like ECG,EEG,arterial pressure
All complex waveforms can be produced by a combo of sine waves |
Biological
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Characteristic of a sine wave: distance b/w any two corresponding pts in successive cycles
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Wavelength
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Characteristic of sine wave: maximum displacement of the wave from horizontal
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Amplitude
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Characteristic of sine wave: time b/w wave cycles
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Wave period
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Characteristics of sine wave: speed of propagation of wave (medium specific)
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Wave velocity
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The higher the frequency the higher the energy content as the wave moves through the medium.
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Wave energy (Sine wave)
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Relationship of one wave to another.
90 degrees |
Concept of phase
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Interaction of two, or more, sine waves.
summation cancellation |
Interference
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Final wave form depends on?
(Sine wave) |
Phase relationship, frequency, and amplitude
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Longer the wavelength, the ____ the frequency
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Lower
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Shorter the wavelength, the ___ the frequency
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higher
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What type of frequency sound travels well through body tissues using the ultrasound?
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High frequency
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What does the ultrasound detect the movement of?
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Rbc by doppler shift
velocity of bld in aorta (CO detector) fetal HR |
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Sends sound signals into tissues. The time it takes to get reflected back tells you how deep layer is and the quality of the signal tells you the type of tissue.
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Ultrasound
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Ultrasound combined with the Doppler can produce?
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Colored maps of bld flow
Bld moves away-red bld moves toward- blue |
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limits to ultrasound?
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Heating of tissues
cavitation |
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Advant:valveless/low resistance, minimal dead space
Disadv:high gas flows:2-3x MV, non-scavenging, SV only |
Ayre's T-piece
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If bld is moving away will have a lower/higher frequency and is called ___ shift?
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lower frequency
Red-shift same effect for doppler & ultrasound |
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If bld is moving towards you it has a lower/higher frequency and is called ____ shift
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higher frequency
blue-shift same for Doppler & ultrasound |
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1)Addition of a bag and single exp. valve
2)Improved efficiency in SV:70% x Vm 3)-Esp. spontaneously breathing pts |
Magil
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the force b/w two charged particles
Two like charges repel, Two opposite charges attract. Double the distance b/w two charges the force b/w them is now 1/4 |
Coulomb's Law
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Electrical potential difference caused by movement of electrons from one material to another.
potential for sparking, explosion,fire sticking of bobbins in gas flowmeters |
Static electricity & electric potential
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-Unit of electrical potential difference/ electromotive force
-causes 1 amp of current to flow through a resistance of 1 ohm |
Voltage
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Equivalent to BP= CO x SVR
current, voltage, resistance Most imp. basic law of electricity |
Ohm's Law
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That resistance which will allow 1 ampere of current to flow under the influence of an electric potential of one volt
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Ohm
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Steady flow of electrons
ex: battery/ generator |
DC
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Steady flow of electrons
ex: battery/ generator |
DC
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Repetitive flow reversals (sine wave)
ex: alternator |
AC
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Coulomb's =?
Farads/capacitance =? |
Amperes*sec
charge/coulombs/volts |
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Electrical burns can be caused by what in the OR?
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poor "ground" pad
disconnect of "ground" pt touching metal table ECG electrodes capacitance linkage small cross section body parts metallic implants implanted electromedical devices |
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intact skin
through the skin 1mA-threshold of perception 5mA-through skin,harmless 10-20mA-"let-go" current 50mA-pain 100-300mA-VF |
Macroshock
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-Vacular access (catheters)
-Myocardial lead wires -Takes shock through pt without penetrating skin -100uA-VF,tiny amp -current density:determining factor in production of VF -150uA capable of producing VF via intracardiac cath -can be produced by <1volt -risk increases with AC -anesthetist can close path to ground from pt resulting in microshock |
Microshock
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larger/smaller area more likely to get a significant burn
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smalller
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temporary internal pacemakers
esophageal stethoscope can be produced by <1volt susceptible pt with Pulm.cath -port cross sectional area very small -contact with ventricular wall,not require much current to cause fibrillation -central line -AFib |
Microshock
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No direct connection b/w the power on the secondary side & ground
introduces a level of safety eliminates the potential of getting shocked through a ground 120volt difference LIM (picks of leakage current) |
Isolated power systems
Isolation transformers & LIM in OR |
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Type___: isolated circuit
electrodes may contact heart directly leakage< 50uA with one fault |
CF
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Type___:
General monitoring circuits (isolated circuit) Leakage< 500uA with one fault |
B or BF
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Mean aortic BP- RAP =
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MAP-0= MAP
BP= CO x SVR |
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Where do you place BP cuff?
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place arrow over artery
witdth of cuff 20%> diameter of the arm |
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absorp capacity= 15L/100gm
Heat: 13,5000 cal/gmw CO2 Temp inside: 45-50deg C indicator: ethyl violet; critical pH 10.3 |
Soda Lime properties
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-Binds to HB x 225 better than O2
-Low conc. may cause PONV,H/A,dizziness -High conc. may cause hypoxia,failure to awaken -Toxicity is r/t conc. & duration of exposure |
Carbon Monoxide (CO)
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Elimination of strong alkali
-NO Na/K/Ba OH -only Ca(OH)2 Elimination all breakdown of volatile anesthetics No production of Compound A or CO Permits sage low-flow/closed system anesthesia, even with Sevo No "regeneration" of color change |
Amsorb plus
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Stoichiometric concentration of alcohol in air?
(saturated vapor concentration) |
6%
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Cool flame burn: characteristic low temp flame seen with saturated __ in air, produces incomplete combustion products
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Ethyl Alcohol
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"Common" Forces
magnet, repelling & attracting electric charges -magnetism resulting from the alignment of the electrical currents in a material that produce a magnetic field -electricity flow of electrons produce an electrical field, electric field can induce a magnetic field that which can induce electricity in another circuit (how transformers wk) |
Electromagnetic
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Permanent/electromagnetic coils
strength: 0.2-4 Tesla Earth magnetic field: 60uT Superconductivity -transition temp, coils are immersed in liquid helium (<4.2K) |
MRI
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Lg forces exerted on feromagnetic materials may cause movement
-internal:tissue disruption -external: injury from projectiles EM fields may -induce electric current in nearby conductors -cause heating of nearby conductors -interfere with monitoring equip Remove all metallic, ferromagnetic, and magnetically recorded materials Pacemaker output can be inhibited Caution: SC stimulators & intra-thecal pumps |
MRI safety
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Most common injury to an organ from a laser?
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eye (temp. blinded)
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light amplification by stimulated emission of radiation
Gain medium: solid, liquid, gas Energy pump: electrical discharge, flashlamp Two mirrors that form resonator cavity |
Laser
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-Specific wavelength (frequency) of emission
-intense parallel beam of light -Coherent light: in phase radiation -continuous or pulsed radiation |
Laser
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Most powerful energy laser used in the OR?
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CO2 laser
cannot see beam used to cut tissue red beam of light is from helium neon |
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Plume-atmospheric contamination: producing .3microns that is transported into alveoli(mutagenic, teratogenic,vector for viral infection bacterial spores)
-Perforation of a vessel/structure -Embolism -Inappropriate energy transfer(ignition) -directly looking into, reflected off something,diffused out |
Laser Hazards
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