Anesthesiology Final Exam Material Flashcards
T/F: Birds have gas exchange in their air sacs
False
The air sacs play an important role in respiration, but are not directly involved in the exchange of gases. Gas exchange occurs in the parabronchial lung
What is the name of the IV access point in the tail of the rat?
Lateral tail vein
What is the best option for preanesthetic medication in a patient with renal disease?
opioid + benzodiazepine
- What about Acepromazine? NO, likely to cause hypotension
- What about Alpha-2 agonists? No, likely to decrease CO and decreased renal perfusion
Are birds more or less sensitive to local anesthetics than mammals?
MORE sensitive
Use <2 mg/kg lidocaine
CSF taps can cause airway obstruction via positioning. How can you avoid this?
Use a reinforced endotracheal tube
What is the most revealing clinical sign of impending malignant hyperthermia?
Rapidly increasing ETCO2
Rapidly increasing ETCO2 is the most revealing clinical sign of impending malignant hyperthermia
What side effect of etomidate would we want to avoid in a CNS patient?
vomiting
Vomiting increases ICP
Would you recommend premedication in a patient with GDV?
Yes
Neuroleptanalgesia with benzo + pure mu agonist opioid IV. This is also the safest choice for patients with unstable CV function
What is the effect of pregnancy on MAC?
MAC is decreased in pregnant patients
So you’re not going to need as much gas to keep your patient asleep and it is much easier to overdose them on inhalation anesthetics
Name three induction agents that you should NOT use in a cat with HCM:
ketamine, telazol, thiopental
What is the arrow pointing at in this ECG?
R-on-T phenomenon
What is the basic MAC value for Isoflurane?
1.3%
What provides the most useful index of cardiopulmonary fitness in dogs?
exercise intolerance
Elephants should always be placed in _________ recumbency
lateral
What’s that?
Pressure gauge or Manometer
It measures and indicates the pressure in this system. The pressure is measured in cm of H2O and will be a negative value during inspiration and will return to “0” during expiration. The pressure will be a positive value during inspiration when the anesthetist will be breathing for the patient (Intermittent Positive Pressure Ventilation or IPPV) either by pushing on the breathing bag or by using a ventilator
Why do we avoid isoflurane in patients with hepatic disease?
We don’t want to avoid isoflurane
Isoflurane ↑ hepatic blood flow, is only ~0.2 % metabolized in the liver, and has less CV depression than halothane, which results in better CO and better perfusion
What is your ECG diagnosis in this 7 month old Labrador Retreiver?
Ventricular tachycardia
Where is the heart located in a snake?
~20-25% body length from the head
Endorphins bind __________ @ pre-synaptic nerve terminal of nociceptor and post-synaptic 2˚ neurons of SC dorsal horn
mu
What premedication helps eliminate “dive response” in birds?
Midazolam
- Dive response is seen in waterfowl. During induction, period of apnea and bradycardia lasting up to 3-5 minutes. This is actually a stress response.*
- Mediated by trigeminal receptors in beak and nares*
I say ‘pain fibers,’ you say:
Aδ and C fibers
When half-life of agonist drug is longer than that of antagonist (reversal drug), the effect is termed:
renarcotization
Animal will recover but then become sedate/anesthetized again once reversal agent wears off
For a first-time accupuncture patient or a debilitated patient, how many points should be selected
less than 10
For subsequent treatments: > 10 points is fine
What induction agent is preferred for C-sections?
Propofol
Historically preferred in small animals, Rapid induction and recovery, Rapid metabolism in neonates, hepatic and extra-hepatic metabolism
What are some contraindications for rehabilitation massage?
open wounds, unstable fractures, severe pain, coagulation disorders, infection, or neoplasia
What is the normal PaCO2 range for arterial blood?
35 - 45 mmHg
Why is the presence of pneumatic bones in birds important to an anesthetic plan?
You do NOT want to place intraosseus fluids in pneumatic bones
Pneumatic bones: Vertebral ribs, sternum, humerus, pelvis, femur, cervical vertebrae, some thoracic vertebrae
How do you correct pulmonic stenosis?
balloon valvuloplasty
What is your ECG diagnosis?
atrial standstill with junctional rhythm
What is Transcutaneous Electrical Nerve Stimulation (TENS)?
Delivery of an electrical current to the skin by surface electrodes placed over the painful region
Provides analgesia by activating non-noxious large myelinated afferent Aβ nerve fibers in the skin and inhibiting small unmyelinated C fibers within the dorsal horn of the spinal cord (“gate theory”)
Contraindications: patients with pacemaker, seizure disorder, pregnancy, over infection, neoplasm, or over the heart
Why are anticholinergics usually given with premedication in neonatal patients?
Neonates/pediatrics dependent on heart rate for cardiac output, so they’re not able to increase contractility or increase stroke volume very well
What is the minimum PCV at which cells can still carry oxygen to tissues?
21%
This correlates to 7 mg/dL Hb
What sedatives do you want to avoid in patients with GDV? Why?
acepromazine & alpha2-agonists
- acepromazine causes hypotension
- even low doses of alpha2-agonists can decrease cardiac output by 50%
In a patient with hypothyroidism, would you expect increased or decreased metabolic rate and drug excretion?
decreased
which means anesthetic drugs are going to be prolonged, etc
What is a possible cause of this ECG?
- Normal ECG in a horse
- Hyperkalemia
- Hypokalemia
- Increased sympathetic tone
Hyperkalemia
Why do you want to mildy hyperventilate patients with renal disease?
Want to blow off CO2 because these patients are normally acidotic and this will decrease CO2
T/F: Avoid ketamine in patients with GDV due to potential for hypotension
True
Name the nephrotoxic breakdown product of sevoflurane degraded by CO2 absorbents:
Compound A
What is the basic MAC value for Halothane?
0.87%
What differences do we see in birds compared to mammals with regard to the diaphragm?
Birds do not have a diaphragm
I have graciously included a picture of an avian diaphragm below.
Name the drug that is a phenol derivative and supports bacterial growth:
Propofol
Phenolic compound causes RBC hemolysis with repeated administration and low glucuronide capacity
What drug is used for etorphine reversal?
Diprenorphine
Has agonist properties (NOT for use in human exposure emergency)
Autoregulation of CBF is very effective when systemic MAP is between _____ and _____ mmHg
Autoregulation of CBF is very effective when systemic MAP is between 60 and 140 mmHg
T/F: Phenylephrine is a significant vasoconstrictor
True
What are the 3 important variables to consider with low-level laser therapy?
wavelength, power, and treatment time
-
Wavelength (determines tissue penetration)
- 630 to 740 nm for AP point stimulation and wound healing
- 750 to 1500 nm for treating ligaments, joint capsule, and intra- articular structures
-
Power (measured in watts or milliwatts)
- More power is not necessarily better, and may even do harm
- Treatment time needed to deliver joules of energy
If you’re anesthetizing a geriatric patient with renal disease, it is important to maintain MAP > _____ mmHg
If you’re anesthetizing a geriatric patient with renal disease, it is important to maintain MAP > 70 mmHg
What is the appropriate temperature for most reptile species?
25-35˚C
- Remember that reptiles are ectotherms, so they rely on external or environmental heat sources for thermoregulation.*
- It is CRUCIAL to maintain each species at OPTIMUM preferred T*
You can gain IV access in turles via the ________ coccygeal vein and in lizards via the __________ coccygeal vein
You can gain IV access in turles via the dorsal coccygeal vein and in lizards via the ventral coccygeal vein
Why might you want to avoid ketamine in a CNS patient?
causes rigidity
Ketamine increased skeletal muscle tone, which increases ICP. So if you DO use ketamine, make sure you use it with a muscle relaxant so you don’t increase ICP
What is the main negative CV effect associated with IPPV?
Decreased venous return
- Negative pressure is not generated during inspiration, so venous return to the heart is not enhanced
- IPPV may actually physically impede venous return to the right side of the heartdecreased stroke volume, cardiac output, and arterial blood pressure
- Exacerbated by prolonged inspiratory time, PEEP/CPAP, obstruction to exhalation, and an excessively rapid respiratory rate
- The CV effects can be overcome often with expansion of the extracellular fluid volume and administration of inotropic drugs
Dynorphin activates __________, and inhibits noceceptive signals to brain
kappa
What is the preferred induction drug for a patient with cardiovascular disease?
etomidate + diazepam
or
midazolam
Start with lower than normal dose initially and give at a slower rate. Transient ventricular arrhythmias can occur during induction, have lidocaine ready. Post-induction apnea can occur, so plan to give IPPV
What differences do we see in birds compared to mammals with regard to the trachea?
Birds have complete tracheal rings!
Do not use cuff inflation in birds!
Name 4 or 5 drugs that reduce cerebral metabolic requirement for oxygen (CMRO2):
- Isoflurane/Sevoflurane
- Etomidate
- Barbiturates
- Ketamine?
- Decreased CMRO2 is seen with CNS depression*
- Decreased CMRO2 is protective*
How long should food and water be withheld from rabbits and rodents prior to anesthesia?
Trick question!
Rabbits and rodents do NOT vomit, so food/water are NOT withheld. We also don’t withhold food/water because these animals are very metabolic and prone to hypoglycemia
What electrolyte abnormalities are Addisonian patients especially prone to developing?
hyperkalemia & hyponatremia
(Na:K ratio < 25:1)
IVF therapy with a balanced electrolyte solution (15- 20 ml/kg/hr) or 0.9% NaCl if hyperkalemic and hyponatremic
Ocular reflexes are a good indicator of anesthetic depth. The bovine eye rotates __________ during light planes of anesthesia
ventromedially
Intraosseous (IO) fluid therapy is more stable than IV in birds.
Name two routes for IO fluid therapy in the bird.
Name two routes for IO fluid therapy that you want to AVOID the bird.
- Good routes: Tibia (proximal) & Ulna (distal)
- AVOID: humerus & femur
Can you use anticholinergics in rabbits?
Yes, but…
Avoid atropine! Rabbits have atropinesterase that breaks it down very quickly. Use glycopyrrolate instead
Following a bilateral thyroidectomy, calcium should be monitored for _____ days
5 days
Hypocalcemia occurs in 15-82% of cats following bilateral thyroidectomy. So calcium should be monitored daily for 5 days postop and treatment only needed if clinical signs develop
Horse dystocia is a serious emergency. About how long after membrane rupture are foals delivered?
30 minutes
Foals normally delivered <30 mins after membrane rupture. Almost none survive >90 mins
T/F: Thermotherapy is generally indicated in the acute inflammatory phase
False
- Thermotherapy is indicated for patients with chronic pain.*
- It is contraindicated during acute inflammation, over an area of hemorrhage or thrombophlebitis, or over malignant tissue*
T/F: Alfaxalone has been shown to be safe and effective for C-section in dogs
True
T/F: Both inspiration and exhalation are an active process in birds and reptiles
True
You take a blood gas analysis of your patient and the PaCO2 is 20 mmHg. Is your patient hypoventilating, ventilating normally, or hyperventilating?
hyperventilating
Normal range for PaCO2 is 35-45 mmHg
When is cryotherapy used?
during the acute inflammatory phase
For post-operative pain or after exercise; reduces inflammation, edema, and pain -> improves mobility, minimizes hematoma formation and reduces muscle spasm
Would you recommend using an induction agent in a patient with GDV?
Yes
Propofol or alphaxalone at low doses
Ketamine + benzodiazepine can be used too
What is the preferred reversal agent for high-potency opioids?
Naltrexone
- Naltrexone is preferred due to long duration of action (helps prevent renarcotization)*
- Naloxone is shorter acting*
What sedatives would you want to avoid in patients with hepatic disease?
acepromazine and alpha-2 agonists
- Acepromazine: hypotension, inhibition of platelet-aggregation
- Alpha-2 agonist: plasma glucose, peripheral blood flow alterations
During low-level laser therapy, protective eye gear must be worn to prevent:
retina damage
Static Magnetic Field Therapy is contraindicated in patients with:
pacemakers!
A continuous magnetic field provided by magnets embedded in wraps, collar, or pet beds that is thought to increase local blood flow and perhaps release endorphins and have antiinflammatory effects
Why do you want to avoid stress in a patient with renal disease?
Stress leads to catecholamine release, which ↓RBF, ↓GFR, ↓ urine production
Also, release of aldosterone, renin, and vasopressin (contributing further to these issues)
What nerve should be blocked when repairing an eyelid laceration?
Supraorbital nerve
***NOTE: The auriculopalpebral nerve block does not desensitize the eyelids!! It only paralyzes them***
Why is electroacupuncture contraindicated in the ventral neck?
You don’t want to hit the carotid bodies
When vasopressors are administered to a patient, what happens to the patient’s heart rate?
reflex bradycardia
Treatment with __________ for 6-12 weeks to reduce total thyroxine to reference range before thyroidectomy significantly reduces perioperative mortality
methimazole
Why should you avoid using ketamine in a geriatric cat with confirmed or suspected heart disease?
can precipitate CHF
Use of the body’s endogenous and restorative analgesic mechanisms to treat disease and pain is termed:
Neuromodulation
Pregnant patients have increased volume of epidural blood vessels and increased epidural fat.
What effect is this going to have on the epidural space and the cranial spread of drugs?
This will DECREASE the epidural space and INCREASE the cranial spread of drugs
A more cranial spread of local anesthetic leads to hypotension. Therefore, epidural drug volume should be decreased by ~1/3 in pregnant patients
In equine patients, MAP should remain above ______ to avoid postanesthetic myopathy
70 mmHg
Neonatal foals have lower BP than adults due to decreased vascular tone, so a MAP of 40-60 mmHg is acceptable
When handling rabbits and rodents, it is important to support:
abdomen and hind limbs
- Otherwise they can fracture their spines and you’ll be “that guy” for the remainder of your veterinary career*
- Lift rat supporting hind quarters with 1 hand, and other one supporting head with thumb under forelimb and mandible*
Epidural drug volume should be decreased by ~_____ in pregnant patients
~1/3
A more cranial spread of local anesthetic leads to hypotension. Therefore, epidural drug volume should be decreased by ~1/3 in pregnant patients
Propofol is the preferred induction agent in many small reptiles. What is the most common adverse affect associated with propofol use in reptiles?
apnea
Why do we avoid halothane in patients with hepatic disease?
decreases hepatic blood flow and up to 20% is metabolited by the liver
There is also a hepatotoxic metabolite (trifluroacetate) formed under hypoxic conditions
How many complete cycles of inspiration and expiration are needed to exchange inhaled gas in birds?
Two
Ideally for an elective procedure, stabilize a hypothyroid patient with __________ for 1-2 weeks
thyroxine
Opioids are okay to use in patients with hepatic disease, but WHY should you avoid morphine if possible?
histamine release
histamine release can lead to hypotension, which can reduce hepatic blood flow
Negative inotropic drugs should be avoided in hypothyroid patients to prevent:
severe hypotension
T/F: LRS is the fluid of choice for use in reptiles
False
AVOID LACTATED RINGERS. There is potential for prolonged half-life of lactate in reptiles
T/F: Calcium and energy excess and rapid growth are known risk factors for developmental orthopedic disease in dogs with a genetic risk
True
Name the only reptile with a 4 chambered heart:
Crocodile
- Most similar to mammalian*
- They also have a foramen connecting L & R aortic arches that carries unmixed oxygenated blood from lungs*
T/F: Stress response can exacerbate conditions such as CHF and acute renal failure
True
Why do you want to avoid alpha2 and opioid drugs in patients with problems in their oral cavity and pharynx?
They induce emesis!
- If you have a patient with problems in their oral cavity and pharynx, you do NOT want that patient to vomit.*
- If you have to give opioids, a good way around this is to wait until your patient is intubated or give IV (risk of vomiting is very low with administration of opioids IV)*
What are the general goals for anesthetic management in a patient with diabetes mellitus?
prevent hypoglycemia at all times, prevent prolonged or severe hyperglycemia (and development of ketoacidosis), and maintain normal fluid and electrolyte balance
If tachycardia and arrhythmias are not controlled in a patient with hyperthyroidism, what drug should be given 3-5 days prior to surgery?
atenolol (6.25 mg/cat PO SID)
Enkephalins bind __________ @ inhibitory interneurons in substantia gelatinosa of dorsal horn↑ GABA et al. in SC
delta
How does PaO2 of geriatric animals compare to that of normal adult animals?
Geriatric animals generally have decreased PaO2
Why might it be difficult to place a jugular catheter in a camel?
thick skin (especially males), no jugular groove, close proximity of jugular vein to carotid artery, etc.
Describe what is occurring in this ECG:
Electrical alternans
How much and how fast can you safely give potassium?
0.5 mg/kg/hr
T/F: Epinephrine can cause severe vasoconstriction and can lead to decreased perfusion of tisues
True
What induction agent causes heinz body anemia in cats?
Propofol
How many air sacs do birds have?
Nine
- 2 cervical
- 1 clavicular
- 2 cranial thoracic
- 2 caudal thoracic
- 2 abdominal
Which nerve(s) need(s) to be blocked when dehorning a goat?
Cornual br. of infratrochlear nerve and cornual br. of zygomaticotemporal nerve
Note that this is different than in the cow! In the cow, only ONE nerve needs to be blocked.
What differences do we see in birds compared to mammals with regard to the epiglottis?
Birds don’t have an epiglottis
Birds have an easily visualized glottis @ base of tongue
When anesthetizing a patient with cardiovascular disease it is important to manage arrhythmias according to severity and nature of the CV disease.
If you have a cat with HCM, what drug should you have available?
beta-blocker
Something like esmolol
T/F: Severely injured patients will have higher resting energy requirements
True
(maybe 2x RER)
How long should medium-sized avian patients be fasted prior to anesthesia?
2-4 hours
To AVOID regurgitation, aspiration, esophagitis, but do NOT fast avian patients < 200g
Where do you gain IV access in a snake?
Jugular vein or palatine vessel
Renal Blood Flow (RBF) is autoregulated in MAP range of _________ mmHg
80-180 mmHg
So any patient with renal disease needs a minimum MAP of 80mmHg!
What is the normal PaO2 range for arterial blood on 100% O2?
~500 mmHg
Which lung is vestigial in snakes?
LEFT (except boas and pythons)
RIGHT lung continues into air sac
T/F: Malignant hyperthermia is caused by a mutation in one gene that controls sodium metabolism in the muscle
False
Malignant hyperthermia is caused by a mutation in one gene (Porcine ryanodine receptor 1 gene) that controls _calcium_ metabolism in the muscle
In a patient with diabetes mellitus, how often should you measure blood glucose during anesthesia?
every 30 minutes
- Measure blood glucose every 30 minutes during anesthesia and once in recovery*
- Maintain BG between 150-250 mg/dL*
Which jugular vein is used for IV fluids in birds?
RIGHT
If you use the left jugular, provide 24 hour monitoring to avoid fatal hemorrhage
T/F: Charcoal absorption systems are useful because they absorb halogenated anesthetic gases, N2O, and CO2
False
Charcoal absorption systems absorb halogenated gases (iso, sevo, des), but do NOT absorb N2O or CO2
In CNS patients under anesthesia, you want to maintain PaCO2 at approximately:
35 mmHg
T/F: Induction drugs have no effect on neuromuscular blockades
False
Induction drugs (Propofol, ketamine, thiopental) have minor enhancement effect on NMB
When managing a patient with diabetes mellitus under anesthesia, it is ideal to maintain BG between _____ and _____ mg/dL
When managing a patient with diabetes mellitus under anesthesia, it is ideal to maintain BG between 150 and 250 mg/dL
Can administer 2.5% or 5% dextrose as needed to prevent hypoglycemia**. Severe hypoglycemia can lead to brain damage that is not apparent until after anesthesia!
What is your ECG diagnosis?
atrial fibrillation
What acid-base abnormality might you expect in a patient with a high GI obstruction?
Metabolic alkalosis
Due to loss of acidic gastric contents via vomiting
Why do we generally avoid using α2-agonists when managing diabetic patients under anesthesia?
α2-agonists cause dose-dependent transient hypoinsulinemia and hyperglycemia
