Anesthesiology - Monitoring 2

drraythe's version from 2016-04-15 10:44

Monitoring continued

Question Answer
What is hypoxemia? (Exact definition?)Low level of O2 in the blood, when SpO2 <90%
What are 5 possible czs of hypoxemia?Hypoventilation (lots of drugs we use cz resp. depression which can lead to this)
Hypoxic gas mixture
Kinked ET tube
Alveolar diffusion impairment
What are 6 limitations w/ the pulse oximetry machine (what are some things that can interfere?)Motion/shivering
Interference w/ ambient light (clinically not that much of a prob)
Use of electrosurgical equipment
Mucosal/skin pigmentation
Abnormal Hb (like methHb, or carbon monoxide)
REDUCED PERFUSION (sensor compresses vessels after a while, hypothermia, hypotension & α-2 adrenoceptor agonists can vasoconstrict & cz them to be too pale to easily read)
What does the apnea monitor do? Explain how it worksMonitors resp rate & has alarms in case of apnea (stops breathing). A Thermistor (resistor whose resistance varies significantly w/ temperature) is placed btwn the ET tube & the breathing system. There is a change in resistance as warmed gasses pass over thermistor which is converted into an electrical signal. The machine beeps w/ each expiration & can be set to signal alarm if there is no breath for a pre-set amount of time
What is Capnography? Whats it good for?Monitoring of the concentration or partial pressure of carbon dioxide (CO2) in the respiratory gases. It is a good indicator of arterial CO2 levels
What is capnography the "ultimate monitor"?Bc it indicates blood flowing to the lung & that the PTx is ventilating, which makes it a good indicator of resp. efficiency
What are the normal values (& what is the value called) for the capnography?Normal = ETCO2 of 35-45mmhg (weirdly, same end numbers as normal pH)
What is the measuring principal of a capnography?IR (infrared) absorption
What are the 2 styles/designs of capnography & what are their pros/cons?(1) Sidestream capnography - Little hose that comes off the side of the elbow of the breathing system. less expensive, but you need to change the lines more often bc they collect moisture
(2) Mainstream capnography is a sensor which directly hooks onto the breathing system through an adaptor & it doesnt clog w/ water or anything but is more expensive & breaks more easily
Explain what the chart for capnography (SLIDE 65) looks like, explain the 4 phases(1) Phase 1 - The "Valley"/ bottomed out flat part is where they are inspiring (no CO2 going through it obv)
(2) Phase 2 - Expiratory phase, where the graph steeply rises as they expire
(3) Phase 3 - the "alveolar plateau" where all the expire gas is from the alveoli so it is a consistent concentration of CO2
(4) Phase 4 - The end of the plateau which is what the end-expired CO2 is & then there is the steep drop where they start to inhale again & bring the line back to 0 as all the CO2 near the capnography is swept away
If the capnography is just displaying 1 big long plateau curve, what problem do you suspect?Some obstruction, prolly in the ET tube
If the capnography has the valley not going all the way down to 0, what problem do you suspect?THIS IS IMPORTANT-IT IS A RE-BREATHING PROBLEM. They are re-breathing CO2 (means CO2 isnt gone from tube when theyre inspiring=badddd)
If the capnography has a weird peak at the end of the plateau where the end tidal CO2 normally is, what problem do you suspect?There might be a leak somewhere, like the cuff isnt inflated properly
If the capnography shows a weird jagged line for the steep line down to the valley when the animal is inhaling, or the entire graph is normal shaped but jagged, what problem do you suspect?This is cardiogenic oscillations - this is from the heart beat. Not really a problem. Curve just looks a bit different.
Explain what re-breathing of CO2 would look like on a capnography.The valley phase where the PTx is inhaling does NOT go down to 0% CO2
What would be 4 reasons that there is re-breathing of CO2?Exhausted absorbent
Incompetent (stuck) expiratory valve
Insufficient fresh gas flow
Leak in the inner tube of a bain system
What is a curare cleft? What does it indicate?A cleft on the capnography where the plateau is more rounded & has a sudden dip in it which goes back up again. This indicates spontaneous breathing during MECHANICAL ventilation which happens during recovery from NMBA & they start "bucking the ventilator" (fighting the ventilator when they start breathing on their own but ventilator is trying to still mechanically ventilate them). Also could be small animal & surgeon is leaning on them too much. (NMBA explanation-give them neuromuscular blocking agent w/ a "curare like effect" (remember the poison dart frog thing?) & then as they start to recover they start to try to breathe on their own against the machine)
What are 3 big reasons for a hypERcapnia?(1) HypOventilation (esp. w/ drugs we give them!!) Keeping more
(2) Re-breathing (other card w/ specific reasons) Taking it back in
(3) ↑ in METABOLISM (malignant hyperthermia, skeletal mm activity, hyperthermia) Making more
*7 possible czs for hypocapnia?HypERventilation, pulmonary embolism (no more gas exchange)
*Cardiac arrest
What would you think if their etCO2 (end tidal) is high? Low?If high (like, 70) (normal is like 35-45), then they arent breathing enough & we can breathe for them. If the etCO2 is really LOW (like, 3) THE ANIMAL IS DYING-LOW CO2 IS AN ALARM SIGN!!
What is the gold standard for evaluation of gas exchange?Blood gas analysis!
Blood gas analysis can be interpreted into what 3 things it tells you about?Alveolar ventilation
Oxygenation (these 1st 2 tell you about resp. fxn)
Acid-base balance
What are the ACTUALLY MEASURED PARAMETERS of the blood gas analyzer? (3) What are the CALCULATED Parameters you get from the measured ones? (4)MEASURED: PaCO2 (partial pressure of CO2 in arteries), PaO2 & pH
CALCULATED: SaO2 (saturated level of O2 in Hb), HCO3-, BE (base excess), TCO2 (total CO2)
What are 3 big indications for doing a blood gas analysis?(1) Resp/cardiac dz **look at ARTERIAL BLOOD
(2) Assessment of efficacy during O2 therapy **look at ARTERIAL blood
(3) Interpret kidney, liver & lung fxn (Acid-base balance) for metabolic & resp problems (like DKA, renal insufficiency, sepsis)
What is the difference btwn paCO2 & pCO2?PCO2 is the partial pressure of CO2. PaCO2 is the partial pressure of CO2 in the ARTERIES (....I don't think she cares too much about the diff tho)
If you are using a blood gas analysis to understand a respiratory or cardiac dz, what are you looking at, what Parameters are you looking at & what blood are you looking at?LOOK AT ARTERIAL BLOOD FOR PARAMETERS OF GAS EXCHANGE: pO2, pCO2, SO2
If you are using a blood gas analysis to assess the efficacy of O2 therapy, what Parameters are you looking at & what blood are you looking at?Look at ARTERIAL BLOOD for pO2 (partial pressure of O2) & the SO2 (oxygen saturation)
Normal pH value for cat/dog?7.35-7.45
Normal PaCO2 value for dog? Cat?CAT: 30-35
DOG: 35-45
(Not sure if we need to know normal?) (3 & 5 have trouble breathing around 4)
Normal PaO2 value for dog? Cat?DOG: 87-100
CAT: 100-110
(of course we'd hope breathing was up to 100)
Normal HCO3 value for dog? Cat?CAT: 16-20
DOG: 22-26
(Not sure if we need to know normal?) (16, 20, 22 & 26 year olds tend to be pretty basic)
Normal BE (base excess) value for dog? Cat?DOG: -4 to +4
CAT:-9 to -2
(Not sure if we need to know normal?)
What is the "rule of 4"?Most normal values have some range involving the number 4 (I noticed this really is only for dogs but she doesn't say this in the ppt)
pH range: 7.4 +/-0.04
pCO2 is 40, +/-4
HCO3 is 24, +/-4
BE is -4 to +4
When might it be normal for a horse to be slightly hypoxemic?If it's on its back during Sx - hard for it to breathe
What’s FiO2?Fraction of inspired oxygen (what you're giving it, basically)
If the PaO2 is really high during anesthesia, what might you be thinking?Providing LOTS of O2 to the animal, when usually atmospheric O2 is 21%, so not weird for it to be high (basically FiO2 ( fraction of inspired oxygen) is higher bc giving them O2, or atmospheric pressure is ↑ → remember partial pressure stuff)
What is oxygen partial pressure dependent on?Inspiratory oxygen concentration!! (FiO2!)
As a rule, optimal PaO2= (what equation?)Optimal PaO2 is what their PaO2 should ideally be w/ however much O2 you supply. So, optimal PaO2 = FiO2x5
What are 3 things that cz hypoxemia (related to O2 supply)(1) ↓ FiO2 (fraction inspirational, i.e. what youre giving it)
(2) Hypoventilation (not breathing what youre giving it)
(3) Venous admixture (diffusion impairment, Right-Left-Shunt (hole in heart), V/Q mismatch (ventilation & perfusion) )
PAO2 vs PaO2?A = Alveoli
a = arteries
What is the NORMAL ventilation/perfusion ratio?V/Q comparing alveoli (PAO2)
Arteries (PaO2)
Veins (PvO2)
So, NORMAL V/Q is PAO2 = 100mmHg, PvO2 = 40mmHg & PaO2 = 95mmHg
There can be a V/Q mismatch if there is no some times there would be a lack of ventilation & how the V/Q values (all three) would be different↓ ventilation from parenchymal dz, collapsed alveoli (pneumonia, pulmonary edema)
Horse on its back. The PACO2 would be <100mmHg (low), the PvO2 would be 40mmHg (same as normal) & the PaO2 would be 60mmHg (normal is 95, so it’s low)
What is the A-a-gradient? What does it indicate & what's normal?It is the difference btwn the PO2 in the Alveoli & the arteries. It indicates the efficiency of gas exchange & is an indicator of lung fxn. NORMAL IS <15 (usually PAO2 is 100 & PaO2 is 95 which is a diff of 5)
What are the 3 steps to a blood gas analysis? (In order)(1) Look at pH-acidemic? Alkalemic? (Normal 7.35-7.45)
(2) Look for cz of acidemia/alkalemia-respiratory or metabolic? (is the PCO2 >45mmHg? is the HCO3 <21mmol/L or the BE <-4mmol/L ?)
(3) Compensation - look at 1° disturbance, see if it fits R.O.M.E. (resp. opposite, metabolic equal), then understand what the compensation would be
If resp acidemia, what's changed & what would compensation bepH ↓
PCO2 ↑
Compensation is ↑ HCO3-
If resp alkalemia, what's changed & what would compensation bepH ↑
PCO2 ↓
Compensations is HCO3- ↓
If metabolic acidemia, what's changed & what would compensation bepH ↓
HCO3- ↓
Compensation is PCO2 ↓
If metabolic alkalemia, what's changed & what would compensation be?pH ↑
HCO3- ↑
Compensation is PCO2 ↑
How frequently should you be monitoring during anesthesia? Record keeping? What should you know about doing this?MONITOR CONTINUOUSLY!! Record keeping should be done every 5 min. HOWEVER, DO NOT JUST STICK TO THE RECORDS IF ANY ISSUES OCCUR & your help is needed
What should you know about the anesthesia record itself?IT IS A LEGAL DOCUMENT. USE PEN. MAKE IT LEGIBLE, MAKE IT COMPLETE. (dont fill a clean version out later bc it is a legal document.)
*Know normal, sp variation, HR, RR, BP, temp, SpO2, ETCO2, mm color, CRTYep

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