Anesthesia- monitoring 2

kelseyfmeyer's version from 2015-11-03 14:39

Monitoring continued

Question Answer
what is hypoxemia? (exact definition?)low level of O2 in the blood, when SpO2 <90%
what are 5 possible causes of hypoxemia?hypoventilation (lots of drugs we use cause resp. depression which can lead to this), hypoxic gas mixture, kinked ET tube, alveolar diffusion impairment, artefacts
what are 6 limitations with the pulse oximetry machine (what are some things that can interfere?)motion/shivering, interference with ambient light (clinically not that much of a prob), use of electrosurgical equipment, mucosal/skin pigmentation, abnormal Hb (like methhemoglobin, or carbonmnoxide), or REDUCED PERFUSION (sensor compresses vessels after a while, hypothermia, hypotension, and alpha2 adrenoceptor agonsis can vasoconstrict and cause them to be too pale to easily read)
what does the apnea monitor do? explain how it worksmonitors resp rate and has alarms in case of apnea (stops breathing). a Thermistor (resistor whose resistance varies significantly with temperature) is placed between the ET tube and 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 with each expiration and 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 (CO 2) in the respiratory gases. It is a good indicator of arterial CO2 levels.
what is capnography the "ultimate monitor"?because it indicates blood flowing to the lung AND that the patient is ventilating, which makes it a good indicator of resp. efficiency
what are the normal values (and what is the value called) for the capnograph?normal= ETCO2 of 35-45mmhg (weirdly, same end numbers as normal pH)
what is the measuring principal of a capnograph?IR (infrared) absorption
what are the two styles/designs of capnography, and 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 because they collect moisture (2) Mainstream capnography is a sensor which directly hooks onto the breathing system through an adaptor, and it doesnt clog with water or anything but is more expensive and 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 consistant concentration of CO2 (4) Phase 4- the end of the plateau which is what the end-expired CO2 is, and then there is the steep drop where they start to inhale again and bring the line back to 0 as all the CO2 near the capnograph is swept away
if the capnograph is just displaying one big long plateau curve, what problem do you suspect?some obstruction, prolly in the ET tube
if the capnograph 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 capnograph 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 capnograph 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 capnograph.the valley phase where the patient is inhaling does NOT go down to 0% CO2
what would be 4 reasons that there is re-breathing of CO2?exhausted absorbent, incompetent expiratory valve, insufficient fresh gas flow, problems with the inner tube of a bain system
what is a curare cleft? what does it indicate?a cleft on the capnograph where the plateau is more rounded and has a sudden dip in it which goes back up again. This indicates spontaneous breathing during MECHANICAL ventilation which happens during recovery from NMBA, and 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 and surgeon is leaning on them too much. (NMBA explanation-- give them neuromuscular blocking agent with a "curare like effect" (remember the poison dart frog thing?) and then as they start to recover they start to try to breathe on their own against the machine)
what are three big reasons for a hypercapnea?(1) hypoventilation (esp with drugs we give them!!) (2) re-breathing (other card with specific reasons) (3) INC in METABOLISM (malignant hyperthermia, skeletal mm activity, hyperthermia)
7 possible causes for hypocapnea?hyperventilation, pulmonary embolism(no more gas exchange), hypoperfusion/hypovolemia, hypometabolism, hypothermia, hypotension, 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 and 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 intrepreted into what three things it tells you about?alveolar ventilation, oxygenation (these first two tell you about resp. function), and also 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, and pH. CALCULATED: SaO2(saturated level of O2 in Hb), HCO3-, BE (base excess), TCO2 (total CO2)
what are three 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 and lung fxn (Acid-base balance) for metabolic and resp problems (like DKA, renal insufficiency, sepsis)
what is the difference between paCO2 and 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, and 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, and what blood are you looking at?look at ARTERIAL BLOOD for pO2 (partial pressure of O2) and 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 normals?) (Three and Five have trouble breathing around Four)
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 normals?) (16,20, 22 and 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 normals?)
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 slihgly 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 atomspheric O2 is 21%, so not weird for it to be high (basically FiO2 ( fraction of inspired oxygen) is higher bc giving them O2, or atomspheric pressure is inc--> remember parial 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 with however much O2 you supply. So, optimal PaO2= FiO2x5
what are three things that cause hypoxemia (related to O2 supply)(1) dec FiO2 (fraction inspirational, ie what youre giving it) (2) hypoventailation (not breathing what youre giving it) (3) venous admixture (diffusion impairment, Right-Left-Shunt (hole in heart), V/Q mismatch (ventilation and perfusion) )
PAO2 vs PaO2?A=alveoli, a=arteries
what is the NORMAL ventilation/perfusion ratio?V/Q comparing alveoli (PAO2), arteries (PaO2) and veins (PvO2) so, NORMAL V/Q is PAO2=100mmHg, PvO2=40mmHg, and PaO2=95mmHg
there can be a V/Q mismatch if there is no some times there would be a lack of ventilation, and how the V/Q values (all three) would be differentDec 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), and the PaO2 would be 60mmHg (normal is 95, so its low)
What is the A-a-gradient? what does it indicate, and what's normal?It is the difference between the PO2 in the Alveoli and the arteries. It indicates the effeciency of gas exchange, and is an indicator of lung function. NORMAL IS <15 (usually PAO2 is 100 and PaO2 is 95 which is a diff of 5)
what are the three steps to a blood gas analysis? (in order)(1) look at pH-- acidemic? alkalemic? (normal 7.35-7.45). (2) look for cause of acedemia/alkalemia-- respiratory or metabolic? (is the PCO2 >45mmHg? is the HCO3 <21mmol/L or the BE < -4mmol/L ?) (3) compensation- look at primary distrubance, 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 and what would compensation bepH down, PCO2 up. compensation is inc HCO3-
if resp alkalemia, what's changed and what would compensation bepH up, PCO2 down. compensations is HCO3- down.
if metabolic acidemia, what's changed and what would compensation bepH down, HCO3- down, compensation is PCO2 down
if metabolic alkalemia, what's changed and what would compensation be?pH up, HCO3- up, PCO2 up
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 and 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 normals, sp variation, HR, RR, BP, temp, SpO2, ETCO2, mm color, CRTyep