VN Q3 Anesthetic Problems & Emergencies
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- Monitoring of anesthetic equipment (5)
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Check for leaks
C02 absorbent is not exhausted
Varify power sources
Verify monitoring device readings
MM color, CPR, pulse - Perfusion
- passage of oxygenated blood through body tissues
- Shock
- inadequate perfusion
- Hypoxemia
-
Insufficient oxygenation of blood
(Pa02 < 60 mm Hg) - Hypoventilation
-
Reduced ventilation
Determined by increase of arterial CO2 levels
PaCO2 > 45mm Hg - Hypercarbia / hypercapnia
- Increased arterial CO2 levels
- Hypotension
-
Inadequate arterial blood pressure
Common sign of cardiovascular depression - Hypovolemia
-
Insufficient circulating blood volume.
Common cause of hypotension.
Fluid administration used as supportive measure. - Hypothermia
-
Abnormally low body temperature
2 - 3 degrees below normal
Sign of nervous system & cardiovascular depression - Ways to evaluate respiratory function (6)
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respiratory rate
tidal volume
breathing patterns
Hb concentration
end-tidal CO2
arterial blood gases - What does pulse oximeter measure
- % of Hb that is saturated with O2
- What does the capnometer measure?
- end-tidal carbon dioxide (ETCO2)
- Ways to evaluate cardiovascular function (7)
-
hr, heart sounds
temp
pulse quality and rate
mm color
CRT
blood pressure
urine output - Ways to monitor cardiovascular function (3)
-
ausculation
ECG
Pulse - Pulse quality
-
how pulse feels when palpated
strong, moderate, weak, thready - Pulse pressure
- difference between systolic and diastolic arterial pressures
- What do cherry red mm indicate?
- Carbon monoxide poisoning
- Response to hypothermia
-
decrease anesthetic concentration
decrease fresh gas flow to minimum requirements
ensure adequate circulation
insulate from cold surfaces; dry the body surface
apply warm blankets, pads - Response to tachycardia (4)
-
decrease anesthetic concentration
increase oxygen flow
increase rate of IV fluids
support ventilation - Response to bradycardia (4)
-
anticholiergics or alpha antagonist
decrease anesthetic concentration
support with 02 and fluids
may be transient - Response to hypotension (3)
-
lower anesthesia
administer fluids
keep warm - Response to hypercarbia / hypercapnia
- increase ventilation
- Reasons for hypercarbia / hypercapnia
-
1) Rebreathing circuits: expired soda lime or faulty unidirectional valves
2) Non-rebreathing circuits: inadequate flow rate
3) Excessive dead space, long ET tube - Response to hypoxemia
- increase inspired O2 concentration and ensure adequate ventilation
- Reasons for hypoxemia (2)
-
kinked/plugged ET tube
empty O2 tank - Response to excessive depth (3)
-
decrease vaporizer setting
increase O2 flow rate
ensure ventilation and circulatory support - Reasons for inadequate depth (5)
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insufficient delivery of anesthetic to avleoli
breathing around ET tube/mask
vaporizer is empty, overfilled, malfunctioning
inadequate flow rate and vaporizer settings
inadequate uptake of anesthetic from alveoli into bloodstream - Reasons for excessive circuit pressure
-
closed pop-off valve
excessive O2 flow rate
occlusion of scavanger system - Checklist for inspection of anesthetic equipment (8)
-
1) sufficient O2 available
2) vaporizer filled
3) gas lines correctly connected
4) sufficient CO2 absorbent time available
5) scavenger system properly connected / functioning
6) cuff syringe available
7) attach breathing circuit, tubes, reservoir bag
8) check for leaks - How do you check for leaks? (8)
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1) close pop-off valve
2) occlude patient end of breathing circuit
3) fill circuit w/ O2 to a pressure of 20cm H2O
4) turn O2 flow to 100ml/min (0.1 L/min)
5) if pressure increases, leaks are withing acceptable limits
6) if pressure drops, increase flow rate until pressure remains stable
7) Leaks exceeding 200ml/min (0.2L/min) should be corrected via machine maintenance
8) open pop-off valve while occluding Y-piece; pressure should drop to 0cm H2O - Why do anesthetic problems occur? (4)
-
human error
equipment failure
adverse effects of anesthetics
patient related factors - Which breeds are at highest risk? (5)
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bulldog
pekingese
brachycephalics
weimaraner
jack russel - Types of human error (4)
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failure to get good history
lack of knowledge of drugs/machines used
incorrect drug administration
personell in hurry, fatigue, careless - Problems with geriatric patients (4)
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reduced organ function
poor response to stress
degenerative disorders
increased risk of hypothermia and overhydration - Ways to decrease risk in geriatric patients
-
IV fluids at reduced rate
select agents with minimal cardiovascular effect
allow longer time for preanesthetics
preoxygenate
reduce anesthesia
keep warm - Problems with pediatric patients (3)
-
increased risk of hypothermia and overhydration
inefficient secretion of drugs
difficult intubation and IV catheterization - Ways to decrease risk in pediatrics (6)
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keep warm
careful w/ pre-op fasting
IV dextrose in LRS
cut ET tubes
dilute injectable drugs
lower doses
inhalent agents over IV
ket/val, no barbiturates - Problems with brachycephalics (2)
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tendency toward airway obstruction
high vagal tone - Reducing risk in brachycephalics (5)
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anticholinergics
preoxygenate
rapid IV induction
delay extubation
observe closely during recovery - Which anesthetic cannot be used on sighthounds?
- barbiturates
- Problems with obese animals (3)
-
accurate dosing difficult
poor anesthetic distribution
respiratory difficulties
shallow breathing results in hypercapnia - Decreasing risk in obese patients
-
dose according to ideal weight
rapid induction
preoxygenate
may need to bag
delay extubation
observe closely during recovery - Problems encountered in dam during cesarean
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increased workload on heart
compromised respiration
tendency to vomit
risk of hemorrhage - Problems encountered with offspring during cesearian
- Anesthetics may cross placenta, causing reduced respiratory and cardiovascular funciton.
- Stragedies to decrease risk in cesarian sx - dam (5)
-
IV fluids
clip before induction
preoxygenate
lowest effective dose of anes
avoid pentobarbital, ket/val - Stragedies to decrease risk in cesarian sx - offspring
-
reversing agents, doxapram
administer O2 by face mask
atropine (bradycardia) - Problems with trauma patients (4)
-
cardiac arrhythmias, 12-72hrs post trauma, often cause of cardiac arrest after HBC
respiratory distress
shock & hemorrhage
internal injuries - Decreasing risk of trauma patients
-
thorough exam
thoracic xrays & ECG
stabilize before anes - Problems with cardiovascular disease (4)
-
compromised circulation
risk of overhydration
pulmonary edema
tendency to develop arrhythmias and tachycardia - Decreasing risk for patients with cardiovascular disease (4)
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preoxygenate
avoid agents that effect heart (halothane, xylazine)
avoid overhydration
diuretics - alleviate pulmonary edema - Problems encountered in patients with respiratory disease (3)
-
poor oxygenation
respiratory arrest
patients anxious/difficult to restrain - Decreasing risk for patients with respiratory disease (7)
-
avoid stress
preoxygenate
no nitrous oxide
induce with IV anes
rapid intubation
control ventilation if needed
monitor closely during recovery - Problems encountered in patients with hepatic disease
-
delayed metabolism
decreased blood clotting
hypoproteinemia
dehydration
anemic / icteric - Decreasing risk in pateints with hepatic disease
-
pre anes blood tests
omit preanes meds
induce with iso or propofol
expect prolonged recovery - Problems in patients with renal disease (3)
-
delayed excretion of anes agents
electrolyte imbalances: hyperkalemia, hyperphosphatemia, metabolic acidosis
dehydration - Decreasing risk in patients with renal disease (5)
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rehydrate before sx, keep H2O till last moment
reduce anes dosage
obtain renal function tests
& electrolyte values
caution with carprofen, acepromazine, xylazine, diazepam, etamine and barbiturates.
IV fluids during sx (urinary obstructions are special cases) - Problems in patients with urinary obstruction (5)
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dehydration
acidosis
azotemia
hyperkalemia
bradycardia - Decreasing risk in patients with urinary obstruction (3)
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avoid barbiturates & IV ket
treat hyperkalemia if present - Brachycephalic breeds (8)
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Bulldogs
Pugs
Pekingese
Shih Tzu
Boxer
Shar-Pei
Boston Terrier
Bull Terrier - Brachycephalic syndrome (3)
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hypoplastic trachea
elongated soft palate
stenotic nares (small lumen) - normal RR
-
dog 8-15 bpm
cat 12-18 bpm - normal HR
-
dog 70-120 bpm
cat 130-170 bpm - normal arterial blood pressure
-
dog 100 mm Hg (mean)
cat 120 mm Hg (systolic) - normal temp
- 100-102 F
- RR requires tx
-
dog <8
cat <10 - HR requires tx
-
dog <60 or >140
cat <110 or >200 - blood pressure requires tx
-
dog <60
cat <100 - temp requires tx
- <98 or >103 F
- critical rr
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dog <4
cat <6 - critical hr
-
dog <40 or >175
cat <100 or >225 - critical blood pressure
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dog <50
cat <80 - critical temp
- <95 or >104
- If the pop-off valve is inadvertently left shut it will...
- cause a significant rise of pressure within circuit
- Brain damage may occur when there is inadequate oxygenation of the tissues for longer than ____ min
- 4
- When a technician is performing CPR alone, the ratio of cardiac compressions to ventilation should be:
- 10:2
- CPR should not be discontinued for longer than:
- 30 seconds
- Signs that ET tube is malfunctioning (4)
-
reservoir bag is not moving
compression of reservoir bag does not result in the raising of the chest
animal is dyspneic
animal cannot be kept at adequate level of anesthesia - Signs that pop-off valve is closed or malfunctioning
-
reservoir bag distended with gas
patient has difficulty exhaling - Which patients are at risk of overhydration
- cardiac disease & pediatrics
- Why are brachycephalic dogs under anesthetic risk
-
excess tissure around oropharynx
increased vagal tone
disproportionally small trachea - Drugs that should be avoided with cardiovascular disease patients
- halothane & xylazine
- How much barbiturate does an animal with liver dysfunction & hypoprotenemia require for induction compared with normal dog
- less barbiturate
- Reasons for light plane of anesthesia
-
ET tube cuff not inflated
incorrect vaporizer setting
incorrect placement of ET tube
use of anesthetic w/ low MAC - Causes of tachypnea
-
Increased levels of arterial CO2
Light anesthesia