VM 737 Anesthesia > Exam 2 > Flashcards

Exam 2 Flashcards

(101 cards)

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1
Q

Methods to monitor oxygenation

A

Pulse oximeter
Blood gas (gold standard)
Cyanosis
Lactate

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2
Q

What does pulse ox monitor?

A

SaO2 (hgb saturation)

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3
Q

SaO2 numbers to know

A
  • > 95% sat = desired, PaO2 >80 mmHg
  • 90-95% sat = mild hypoxemia, Pa 60-80 mmHg
  • <90% sat = severe hypoxemia, Pa <60 mmHg
  • 70% SaO2 = PaO2 40 mmHg
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4
Q

What does blood gas measure?

A

PaO2, Pa/vCO2

Allows you to assess O2 exchange at alveoli via A-a gradient, P/F ratio

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5
Q

When does cyanosis occur?

A

When you already have a problem

PaO2 <40 mmHg

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6
Q

What does Lactate measure?

A

Indirect measure of anaerobic metabolism

Lactate increases w/ severe hypoxemia

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7
Q

Methods for monitoring ventilation

A

Capnograph/Capnometer
Blood gas
Acid/base balance

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8
Q

What’s normal end tidal (at end of exhale) Co2

A

30-45 mmHg

highest point of capnograph, D

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9
Q

What is the difference between blood PCo2 and end tidal CO2?

A

0-10 mmHg b/c mixes w/ dead space oxygen, Co2 gets diluted slightly

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10
Q

What is the difference between PaCO2 and PvCo2?

A

PvCo2 ~5 mmHg higher (very small diff)

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11
Q

Arterial and venous blood samples are comparable for ___ but not ___?

A

comparable for PCO2 but not PO2

should only use arterial samples for accurate PO2 measurement

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12
Q

Why can’t you use a capnograph/nometer for small <5 kg patients?

A

b/c on a bane circuit so higher O2 flow = further dilution of CO2, inaccurate measurement

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13
Q

What does acid/base balance measure

A

Indirect measure of Co2 conc b/c CO2 and bicarb are related
Hypoventilation –> high CO2, resp acidosis
Hyperventilation –> low CO2, resp alkalosis

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14
Q

Ways to monitor respiratory activity during anesthesia

A

Subjective/visually: Resp rate, pattern, rhythm, volume, effort

Respirometer/Ventilometer: tidal vol, minute ventilation

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15
Q

EQ diff’s w/ anesthesia

A
  • maintain a higher PCO2
  • greatly affected by position (V/Q mismatch)
  • cluster breathing normal, hypoventilation common
  • typically maintain lower HR (up to 40% decreased CO under anesthesia)
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16
Q

Cat diff’s w/ anesthesia

A
  • Maintain a lower PCO2
  • predisposed to airway obstruction (mucus, small airway)
  • hard to intubate
  • airways reactive, prone to trauma
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17
Q

Dog diff’s w/ anesthesia

A
  • depressed by opioids
  • predisposed to aspiration pneum.
  • brachycephalics
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18
Q

Lab animal diff’s w/ anesthesia

A
  • hard to intubate and monitor
  • affected by position
  • predisposed to airway obstruction (mucus, small airway)
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19
Q

marine mammal/ diver diff’s w/ anesthesia

A
  • diving reflex/breath holding
  • may drown w/ anesthesia or during recovery
  • hard to intubate
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20
Q

amphibian diff’s w/ anesthesia

A
  • skin breathers

- hard to intubate or monitor

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21
Q

bird diff’s w/ anesthesia

A
  • no alveoli, no diaphragm = ventilation required
  • for FRC
  • greatly affected by position, airway prone to obstruction (mucus)
  • hard to monitor, sensitive to inhalants
  • complete tracheal rings
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22
Q

Rum diff’s w/ anesthesia

A
  • hard to intubate
  • greatly affected by position
  • salivation = predisposed to asp. pneum.
  • higher resp rate but smaller tidal vol than EQ
  • often hypertensive w/ anesthesia
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23
Q

What’s important about sheep and anesthetic drugs?

A

alpha 2 agonists will cause hypoxemia

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24
Q

SAC diff’s w/ anesthesia

A
  • hard to intubate (mouths don’t open wide)
  • Good oxygenators
  • regurge/asp. pneum. risk
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25
Pig diff's w/ anesthesia
- hard to intubate (90 deg larynx, small airway) - short necks (can intubate a bronchus) - unknown underlying dz possible
26
Oxygen delivery formula
DO2 = CO x CaO2 (oxygen content)
27
What determines CaO2
hgb conc, PaO2
28
Cardiac output formula
CO = SV x HR
29
Factors affecting SV
preload afterload contractility
30
Other factors affecting CO
arterial BP blood vol systemic vascular resistance
31
How can you increase SV during anesthesia?
increase preload (e.g. increase blood vol) but avoid excess (--> edema, pulmonary edema) increase contractility (inotropic drugs) decrease afterload (vasodilation) - not recommended b/c decreases BP/perfusion
32
How to increase HR during anesthesia?
- sympathomimetics (ephedrine) | - parasympatholytics (atropine, glycopyrrolate)
33
If you wanted to increase CO during anesthesia, would you rather increase HR or SV?
SV | Increasing just HR decreases filling time, but increases work - only increases CO a bit
34
How to increase BP during anesthesia?
Modulate chatecholamine receptors | support blood volume
35
Catecholamine receptors actions
a1 - vasoconstriction (increase SVR) a2 - vasoconstriction (increase SVR), bradycardia (decreased HR) b1 receptors - tachycardia & increased contractility (increase CO) b2 receptors - vasodilation (decrease SVR)
36
CV complications during anesthesia
``` Bradycardia Tachycardia Decreased contractility Rhythm disdurbances Vasomotor (blood vessel) tone change ```
37
Treat bradycardia
``` Fix cause of problem Give anticholinergic (atropine, glycopyrrolate) ```
38
What drugs cause bradycardia
opioids alpha 2 agonists anticholinesterases
39
What drugs cause tachycardia
ketamine | anticholinergics (glyco, atropine)
40
Treat tachycardia
fix cause of problem | Beta-blockers as last resort (Esmolol)
41
Treat for decreased contractility
decrease anesthetic plane | Inotropes to increase contractility (Dobutamine, Dopamine, ephedrine)
42
How to diagnose an arrhrythmia?
ECG
43
What drugs cause vasodilation?
Propofol Isoflorane Acepromazine
44
What drugs cause vasoconstriction?
alpha 2 agnoists | ketamine
45
Treat vasodilation
Increase blood vol or CO | Give a vasopressor (vasoconstrictor) - Dopamine, phelephrine
46
Treat vasoconstriction
Reverse or stop vasopressors | Give vasodilator - Ace, sodium nitroprusside, hydralazine, amlodipine
47
PE indicators of cardiovascular function
- demeanor, activity level, temp - dyspnea d/t decreased DO2 or pulmonary edema from heart failure - Pulse rate, rhythm, quality - mucus mem color - CRT - hydration status - ascultate
48
Considerations about pulse pressure
- not the same as BP - measures difference btwn systolic and diastolic pressures (similar P's = weak pulse, big diff = strong pulse) - pulse may be absent when MAP <40 mmHg (hypotensive) but pulse pressure could still be nx
49
Normal amount of water in the body & where it lives
60-80% of bodyweight 60% is intracellular 40% is extracellular (10% in extravascular, 30% interstitial)
50
normal blood volume in the body
5-9% of bodyweight
51
Ways to assess hydration
- skin turgor - tacky mm - hemoconcentration (increased PCV, TP) - increased Cr, BUN (if severe), concentrated urine, low urine output - tachycardia - decreased bw, depression, lethargy
52
Ways to monitor CV function during anesthesia
- direct CO monitoring (gold standard) - HR - Arterial BP (important, early indicator of trouble)
53
Blood Pressure formula
BP = CO x SVR (systemic vascular resistance)
54
Normal SAP (systolic arterial pressure)
100-140 awake | >90 SA, >100LA anesthetized
55
Normal MAP (mean arterial pressure)
80-120 awake | >60 SA, >70 LA anesthetized
56
Normal DAP (diastolic arterial pressure)
60-80 awake | >50 anesthetized
57
Ways to measure BP
Direct: arterial catheter (gold standard) Indirect: doppler, oscilometric
58
Cuff width for accurate estimate of BP
needs to be 40% limb circumference | too small width = overestimation, too big = underestimate
59
Doppler vs. oscilometric
Doppler - has crystal, gives SAP only | Oscilo - no crystal or sphygmomanometer, SAP, MAP, & DAP given
60
Why is hypotension bad?
oxygen delivery likely decreased
61
Consequences of mild but prolonged hypotension
CNS damage Renal & hepatic damage/failure GI & muscle tissue necrosis
62
Consequences of severe hypotension
severe CNs damage severe myocardial damage acute death
63
Treat hypotension
Try to increase CO & tissue perfusion first (to maintain DO2) Vasoconstriction could increase SVR, but could also decrease perfusion more - tricky
64
Treat hypovolemia
Restore blood volume by crystalloids, colloids, blood products
65
Risk of a too long ET tube
increased dead space | goes into a bronchus --> hypoxemia, hypoventilation, decreased anesthetic plane (common in pigs)
66
Proper cuff inflation
Inflate cuff until don't hear leak when squish bag to ~10-15 cmH2O PIP (SA, 20-30 for LA) Should hear safety leak if squish bag to 20-30 cmH2O
67
Consequences of cuff overinflation
trauma --> tracheal rupture, pneumothorax & pneumomedastinum LA - trachea will collapse ET tube ET tube obstructs itself
68
Indications for mechanical ventilation
hypoventilation hypoxemia increase inhaled anesthetic depth logistics
69
With mechanical ventilation, how do you adjust inspiratory time?
larger animal = longer time | smaller animal = shorter time
70
What's normal tidal vol? Minute ventilation?
TV: 10-20 ml/kg MV: 100-250 ml/kg/min
71
How do neuromuscular blockers work?
block ACh receptors --> paralysis | Good for orthopedic, ophthalmic, CNS procedures or EQ deep abdomen procedures
72
neuromuscular blocker drugs
Cis-atracurium, atracurium, vecuronium
73
Key component for neuromuscular blockade
assisted ventilation & monitoring of paralysis
74
Reversals for neurmuscular blockers
Edrophonium Neostigmine (mg diagnostic) suggamadex-Rocuronium Physiostigmine (mg treatment)
75
Risk w/ poor padding/placement during surgery
ischemia, post-op pain nerve damage rum - asp. pneum. EQ - edema
76
Why is thermoregulation important w/ anesthesia
decreases metabolic rate, thus heat --> hypothermia | occurs faster in younger (less E stores) or smaller animals (more SA)
77
Consequences of hypothermia
prolonged recovery, prolonged drug metabolism decreased MAC Impaired coag, delayed wound healing increased mortality rate
78
When do you pull the ET tube
SA - strong swallow Rum - sternal, holding head up EQ - standing Brachycephalics - as late as possible
79
How do crystalloids treat dehydration
restore water & electrolytes, increase extracellular vol
80
Types of crystalloids
LRS physiologic saline (0.9% NaCl) normosol plasmalyte
81
Water is normal daily water intake?
1-5 ml/kg/hr or 20-120 ml/kg/day | lower side for larger animals
82
How much crystalloid is given to anesthetized patients (as a guideline)?
1-10 ml/kg/hr Usually a conservative bolus first - 10-20 ml/kg Expect it to move from intravascular to extravascular space in 30-45 mins
83
How much of a bolus do you give for shock?
50-100 ml/kg
84
Why would you use colloids over crystalloids
colloids have high oncotic pull, so stay in vasculature longer (6-48 hrs vs. <1 hr) BUT can fluid overload and other issues, so limit dose
85
Types of colloids
Hetastarch, Dextran, Albumin, Oxyglobin
86
When do you usually give blood products & how much do you give?
PCV <20 ot TP <3.5 | Give 1-5 ml/kg/hr (faster if active bleed)
87
how do you treat acidosis in an emergency
bicarbonate | bicab = bs x base deficit x 0.3
88
How do you treat alkalosis in an emergency
physiologic saline
89
How do you treat hypoglycemia
1-5% dex as needed | required glu = bs x 0.3 x (desired glu - current glu level)
90
How do you treat hyperglycemia
insulin
91
Expectations of resp func in EQ under anesthesia
hypoventilation - mechanical ventilation required V/Q mismatch (impacted by recumbency) leave ET tube in until STANDING (w/in 1 hr post anesthesia)
92
EQ common protocol for sedation
alpha 2 agonist (Xylazine, detomadine, ___dine) Ace - take edge off early on +/- butorphanol or morphine
93
EQ common induction protocol
Ketamine + diazepam/midazolam +/- guaifenesin | no propofol - wierd behaviors
94
EQ common maintenance protocol
<1 hr = total IV: Triple Dip (XDK) or G/MKX | >1 hr = G/MKX, then CRI of K & X, then inhalant
95
Monitoring EQ during inhaled anesthesia
- must measure arterial BP (MAP should be >70 mmHg) d/t decreased CO & hypotension --> myopathy - must treat hypotension - ideally, ECG - take periodic blood gas (esp. w/ inhaled anesthetics) b/c pulse ox & capnograph less reliable in EQ
96
Options for systemic EQ pain management
- Alpha 2's used commonly - opioids (but combined b/c cause excitation, ileus) - maybe lidocaine or ketamine CRI to decrease anesthetic requirement (and Ketamine improves CO)
97
Options for local/regional blocks in EQ
local anesthetics for distal extremities only Opioids (combined w/ alpha 2) - longer lasting NSAIDs - traditionally used
98
Why are opioids so commonly used in combo w/ other drugs for anesthesia?
analgesia peri-operative sedation large margin of cardiovascular safety shorter acting drugs (e.g. fentanyl) decrease dose of IA needed & decrease risk of drug accum
99
Who should you use opioids very cautiously in?
Horses | behavioral issues & ileus, inconsistent effects
100
When would you use a ketamine CRI in combo w/ IA's for anesthesia?
- reduces windup | - reduces anesthetic requirement of IA's
101
hypercapnea causes
vasodilation and tachycardia

VM 737 Anesthesia (4 decks)

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