Anesthesiology - Midterm 1

drraythe's version from 2016-03-07 00:15



Question Answer
O2 in the US
*O2 - UK & US color?US-Green    UK-White
N2O - UK & US color?Both Blue
Medical air in the US
Suction in the UK
*White - US & UK
Suction in the US
O2 in the UK
*Medical air color US & UK?US: Yellow   UK: Black & White
Brown & Green together
Helium & Oxygen
Conc in alveoli =Conc in brain
O2 filling pressure2000 PSI (136 ATM)
N2O filling pressure745 PSI (51 ATM)
Filling ratio equation
O2 pipeline pressure58 PSI (4 ATM)
*Size E tank PSI & liters1900 PSI (130 ATM) 680L
*Size H tank PSI & liters2,200 PSI (150 ATM) 6900L
Calc content of O2 tankO2 gas only, pressure gauge is accurate. So Content is VOL x PRESSURE = Liters of O2
**Pressure regulator takes _________ O2 from tank & makes it _________ (pressure)2000 PSI, 50 PSI
(136 ATM, 3.5 ATM)
**Flowmeter takes __O2 from the Pressure regulator & makes it _________50PSI, 14.7 PSI
(3.5 ATM, 1 ATM)
**O2 flush valve delivers what at what rate?100% O2 at 35-75 L/min (~50 PSI of pressure! Can cz Barotrauma) (emergency only! try not to use this when PTx is connected)
*Flow meter: Measure bobbin from? Ball from?Bobbin from top (widest part)
all from middle
*Charcoal scavenge system limitation?CHARCOAL DOESNT ABSORB N2O
*A Reservoir bag should be _________-_________ times larger than the animals tidal volume3-6
Reservoir bag for cat size?0.5L
Reservoir bag for dog size?0.5 to 3L
Reservoir bag for horse size?25-30L
**Soda lime + sevo possibly makes (under poor conditions)Compound A (nephrotoxic) (*change yo lime!)
Soda lime + des/en/iso possibly makes (under poor conditions)Carbon monoxide (CO) (*change yo lime!)
Size of animals for rebreathing system?GREATER THAN 7kg
What’s the relation of fresh gas flow & minute volume (volume breathed in 1 minute) in a REBREATHING system?Fresh gas flow < minute volume - this is bc you're recycling air so don't need a high FGF
*Name the 2most popular non-rebreathing systems(1) Mapleson D
(2) Bain (Co-Ax design)
*Name the 2most popular rebreathing systems(1) Circle
(2) Universal F (Co-Ax design)
FGF for REBREATHING for INDUCTION? (Know units)~40-100 ml/kg/min
FGF for REBREATHING for LOW LOW (basically maintenance)About 20 ml/kg/min
**FGF CALCULATIONTidal volume x RR (physiological) x weight x system factor (NOTE: Tidal volume times RR is aka the Vm aka minute volume, so can also be said as minute volume x weight x system factor)
FGF for NON-rebreathing systems is related to the MV (minute volume) how?It's greater than or equal to (not recycling any gas, might need more to clear system in fact)
**FGF for NON-rebreathing system if FGF is equal to MV? If FGF is greater than MV?FGF = MV: 200 ml/kg/min
If FGF > MV: 400-600 ml/kg/min (Total range = 200-600 ml/kg/min)
**Non-Rebreathing system relies on?High FGF!
REBREATHING system → HIGH FGF. Average amount for horse? Small animal? When is high FGF used/how long?Usually at start (15-20min) & sometimes at end (faster induction & recovery)
HORSE: 8-10L/min
Activated charcoal: you must do what & what doesnt it help w/?Doesnt absorb N2O, need to weigh to determine if spent
Pressure provided for machine should be _________ to _________ (pressure)50-58 PSI
(3.5-4 ATM)
The pressure going to the animal which is on the pressure valve should never exceed ___cmH20 on the pressure dial20 (0.001 ATM)
Steps for leak testOcclude PTx end → close pop off valve → turn on flow meter to fill reservoir bag until pressure is 30 cmH2O on pressure gauge (watch if pressure starts to go down on gauge) → squeeze bag till the pressure is at 40 cmH2O (see if pressure starts to go down on gauge) (if no pressure gauge, bag size shouldn't change) → at end OPEN POP OFF VALVE → THEN remove your hand from PTx end
Approx pressure in a tank totally full of O2?2000 PSI (136 ATM)
In WHICH system do you calc the FGF & why not the other?Calc for the NON rebreathing. don't have to for re-breathing bc the flow is less than the minute volume so there's no way you're gonna pop the lungs. Non-re-breathing you CAN pop the lungs, so you need to calc the FGF which wont result in a dead animal
When calc the FGF (once again, for which type breathing system), what's the usual system factor?(Non-rebreathing) 2-3x
Calc minute volumeTidal volume times RR (tidal volume is usually 10-15 mLkg^-1 & RR is usually like 12bpm)
(Clarence says-& I'm not sure if she cares, but) for a rebreathing system, the high flow is 40-100mg/kl/min. which end of the range is for small animals & which end for large animals?40 = Large animals
100 = Small animals
(bc large animals are big & you need to consider cumulative effect)
Why must the FGF be higher than the minute volume in the non-rebreathing system?Bc it needs to be a sufficient amount to carry away the CO2 (bc no soda lime)
Is N2O a liquid or gas? Think about it in a tank & when it is madeIt's the only anesthetic which is packaged as a gas
HOWEVER, the compression in the tank czs it to become in a liquid state inside. Which is why you need to weigh it to determine how much is in there. But it is the only anesthetic that is a gas, not a volatile liquid


Question Answer
Uncuffed ET tube in?Birds
Sm mammals
To check if right ET tube length?Incisors to tip of shoulder
Cats & sheep/goats, pigs, rabbits, monkeys laryngospasm, do what?Lidocaine spray (just a little) & DONT TOUCH EPIGLOTTIS
What Parameter can you check on the machine to see if the tube is in the trach & not the eso?END TIDAL CO2 (if up & down, normal, if flat & low, in eso)
If a doc says "get me an ET tube 8" what is the 8 referring to?The INTERNAL DIAMETER


Question Answer
Which is more irritating to use in induction chamber - Sevo or Iso?Iso more irritating
Sevo is less irritating
What is partial pressure?If there is a mix of gases in a container, each gas exerts its own pressure on the walls. So the total pressure is the SUM of all the partial pressures of all the gases in the mix (this is why it's hard to breathe in the mountains-the PP, not the amount of O2 (%), its the partial pressure)
What is SVP? (Saturated vapor pressure)Maximum possible concentration of molecules in the gaseous phase at a specific temperature (for volatile fluids)
A high SVP is a....less or more volatile agent?High SVP = more volatile
What has the highest SVP (saturated vapor pressure)? Lowest? (Know general trend)Des is highest
(How do you determine the % concentration of the volatile liquid in the air? ← don't think we need to know)The SVP/atmospheric pressure
Vaporizer is needed to ___ inhalational agents to a safe concentrationDILUTE! (Their SVPs are usually way higher than what is needed)
What are the boiling points like (order of highest to lowest)Halothane > Sevo = Iso > Des > N2O
What is notable about desflurane's boiling point?It’s RIGHT AROUND ROOM TEMP (23.5*C) so need a SPECIAL VAPORIZER (also N2O is-89 so will only always be gas)
Partition coefficient is the expression of what?Solubility
Equilibrium refers to when the ___ equilibrate btwn gas & liquidPARTIAL PRESSURES (conc may be different)
Blood gas partition coefficient is INVERSELY RELATED TO _________?Speed of anesthetic induction, recovery & change of anesthetic depth. (The HIGHER the partition coefficient, the SLOWER the induction, recovery & change of anesthetic depth)
Blood gas partition coefficient (B:G PC) basically represents the...SOLUBILITY. Which makes sense as to why it's inversely proportional to speed of induction...bc if something is super soluble, it will want to STAY in the blood & not diffuse to the brain, so it'll take more & longer to induce
List the anesthetics in order from highest B:G PC to lowest(Longest induction) Halothane > Iso > Sevo > Des > N2O (fastest induction) (HISDN - same as O:G)
Alveoli → blood depends on what PC?B:G
Blood → brain depends on what PC?B:G and O:G
Oil gas partition coefficient is DIRECTLY CORRELATED TO___?POTENCY
List the anesthetics in order from highest oil gas to lowest(most potent) Halothane > Iso > Sevo > Des > N2O (HISDN - same as B:G)
How are cardiac output & induction rate related?LOW CO means FASTER induction (blood moving more slowly gives gas more time to diffuse into it)
Anesthesia achieved when there is adequate ___, which occurs whenBrain tension (i.e., enough concentration in brain). Occurs when equilibrium (remember equi is PP not conc) is alveolus/blood/brain
How can you accelerate "washout" from tissues when inducing recovery?Give a high FGF & empty reservoir bag
MAC (what is it?) is the standard index of what?Anesthetic potency (MINIMUM alveolar concentration) (basically the min conc that will produce immobility in 50% subjects exposed to painful stimuli)
Is MAC directly or inversely related to potency?INVERSELY. That is to say, the HIGHER the MAC, the lower the potency
Relation direct or inverse for... B:G, O:G, MAC?B:G = INVERSE to solubility
O:G = DIRECT for potency
MAC = INVERSE to potency
**List the anesthetics in order of HIGHEST MAC to lowest(LEAST POTENT) N2O > Des > Sevo > Iso > Halo (most potent) (HISDN backwards. lol)(the most potent Nuthatch does swim in hell)
FI = Fractional Inspired (inhaled) ET = End Tidal (exhaled)...which of these represents the amount in the brain?ET (compared to the MAC)
Some stuff that ↓ MAC(This means to make anesthetic more potent)
Sedatives/analgesics/injectable anesthetics
Older animals
Severe Hypoxemia (PaO2<40)
Severe Hypercapnia (PaCO2>90)
Concurrent illness
How does N2O affect MAC?Nec mac, which means giving N2O ↑ potency of what you're giving
How much does N2O affect the CV system?Minimally
Fastest inducer & recoverery?N2O
You need to mix O2 w/ NO2 or you will cz hypoxia. What’s the minimum proportion of O2 you need in the mix?Not less than 1/3 O2....and the MAC of N2O is like 200%, w/ at least 50% needed to see an affect.
Explain "second gas effect" & which anesthetic this usually is referring toN2O! When N2O is given w/ another anesthetic gas, it speeds up the initial intake of that other gas. This is bc of N2O's diffusibility & HIGH partial pressure gradient (basically, the gases like to move together, so the anesthetic gas follows the N2O)
Why must you be careful w/ N2O in particular situations? (What situations?)N2O DIFFUSES INTO GAS FILLED SPACES! (Rumen, stomach during GDV, closed pneumothorax, ocular Sx) & then N2O DIFFUSES FASTER than it can leave... leads to EXPANSION of this air-filled cavity
Explain diffusion hypoxia, what gas this happens w/ & what you must doN2O diffuses rapidly!! bc of this, after administration of gases is stopped, the N2O rapidly diffuses into the alveoli & then it DILUTES THE O2 in the alveoli. This runs you the risk of hypoxia. Therefore, provide O2 for 10min after turning off N2O
What are the benefits of N2O?2nd gas affect (faster induction w/ anesthetic gas), MAC sparing, ANALGESIA
What are the disadvantages of N2O?Low potency, diffusion into gas-filled spaces, potential for hypoxia, drug abuse, environmental impact (worst for environment)
Why do we care about the fact halothane is preserved w/ 0.01% thymol?Can make knobs sticky
CV effects of halothane?Depresses myocardial contractility → reduces CO, SV, MAP (cardiac output, stroke volume & mean arterial pressure) is also ARRYTHMOGENIC (sensitizes myocardial conduction to catecholamines)
Most potent anesthetic that isnt halo?Iso
Which anesthetic is metabolized the most?Halo
Which anesthetic creates compound A & when is this most likely to happen?Sevo, w/ low flow gas (nephrotoxic compound)
Which anesthetic needs a special vaporizer & why?DESFLURANE, bc its super volatile bc its boiling point is 23.5*C which is like room temp (vaporizer requires special elec. power & heats des to 39*C & it is pressurized)
What is malignant hyperthermia? Who does it happen in most commonly? What can trigger this condition?A potentially life-threatening myopathy what is a heritable dz (hyperthermia, mm fasciculation, tachycardia). Humans>PIGS>horses+dogs>cats. It can be triggered by all 4 current volatile agents (& depolarizing NM blockers)
What drug can you use to Tx malignant hyperthermia?Dantrolene (Dan is too hot for his own good)
(Not sure how important) recommended trace limits in the US?25ppm Nitrous Oxide, 2ppm any halogenated anesthetic agent (UK= 100ppm N2O, 50 iso, 10 halo)
Risks to ppl exposed to N2O?Miscarriage & ↓ fertility if exposed to high N2O conc
Which anesthetic can rarely cz hepatitis?Halothane (hepatic necrosis & death from immune mediated rxn, previous exposures to traces might predispose)
Which anesthetic might cz Alzheimer’s?Iso

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