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Anesthesia Exam 2

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whether the fluid loss you are trying to replace was acute or chronic, the type of fluids being used
What factors will affect the speed with which you give fluids?
Cl, then K and NA; hypochloremic metabolic alkalosis
What metabolites are of concern with losses in vomit? Resulting condition?
bicarbonate; hyperchloremic metabolic acidosis
What metabolites are of concern with losses in diarrhea? Resulting condition?
skin pliability, HR, character of peripheral pulses, CRT, peripheral venous distension, body weight
What are parameters that should be evaluated to determine level of dehydration?
moisture of mm, skin tent, eye position, corneal moisture
With interstitial fluid loss, what parameters are altered?
interstitial fluid
What compartment of fluid is harder to assess in obese, emaciated, and young animals?
perfusion parameters: MM color, CRT, HR, pulse quality, jugular distensibility
With intravascular fluid loss, what parameters are altered?
impossible to determine on PE; see changes in Na+ concentration in the ECF
With intracellular fluid loss, what parameters are altered?
<5%
Identify the level of dehydration: dehydration is not detectable
5-6%
Identify the level of dehydration: subtle loss of skin elasticity
6-8%
Identify the level of dehydration: definite delay in skin return to normal position ,slight prolongation of CRT, eyes maybe sunken in orbits, maybe dry MM
10-12%
Identify the level of dehydration: skin tent stays in place, definite prolongation in CRT, eyes sunken in ornits, drey MM.
10-12%; tachycardia, cool extremities, rapid, weak pulses
At what level of dehydration do you expect to begin to see signs of shock? What signs would you see?
12-15%
Identify the level of dehydration: definite signs of shock- tachycardia, cool extremities, rapid, weak pulses
80-90 mg/kg
What is the shock dose in a dog?
they are likely dehydrated
With high PCV and TS, what can you conclude about a patient?
30 mins
How long will a bolus of isotonic fluid remain in the vasculature?
prevents clot formation in the line
What is the advantage to running fluids at high rates?
can overload the system with fluids, causing edema and 'jiggly skin'
What is the disadvantage to running fluids at high rates?
5 ml/kg/hr
What is the fluid rate for a dog under anesthesia?
3 ml/kg/hr
What is the fluid rate for a cat under anesthesia?
decrease inhalant rate, give crystalloid bolus(es), use vasopressor (dopamine)
What are the steps for treating anesthesia-related hypotension?
pulse rate/quality, CRT, BP (invasive), O2 saturation, MM color, RR and effort, lung sound, skin turgor, urine output, temp
What are clinical signs that can be used to monitor fluid therapy?
PCV, TP, serum lactate, electrolytes, CRE, BUN, USG
What are lab tests that can be used to monitor fluid therapy?
anesthetic drugs, low venous return
What are the #1 and #2 most common causes of hypotension under anesthesia?
they are unable to adequately autoregulate blood
Why must you treat hypotension aggressively in anesthetized patients?
SV x HR
Give the equation for CO
preload, contractility, afterload
What affects SV?
CO and SVR
What affects BP?
CO and O2 content
What affects O2 delivery to tissues?
Hb, Hb O2 saturation, PP arterial O2
What affects arterial O2 content?
70 ml/kg
What is total blood volume in a dog?
60 ml/kg
What is total blood volume in a cat?
20 kg x 70 m/kg= 1400 mL; 5% of 1400 mL= 70 mL
How do you calculate the 5% of the total blood volume in a 20 kg dog?
5-10 ml; 5 if saline is mixed with it
How much blood is contained in a 4 x 4 sponge?
50-100 ml; 50 if saline is mixed with it
How much blood is contained in a lap sponge?
ASA PS 1
What is the ASA status for a normal, healthy patient?
ASA PS 1
What is the ASA status for a patient undergoing an elective dental?
ASA PS 1
What is the ASA status for a patient undergoing an elective surgery?
ASA PS 1
What is the ASA status for a patient undergoing a declaw?
ASA PS 2
What is the ASA status for a patient with mild systemic disease?
ASA PS 2
What is the ASA status for a patient undergoing a fracture repair without shock?
ASA PS 2
What is the ASA status for a patient undergoing a skin tumor removal?
ASA PS 2
What is the ASA status for a patient undergoing surgery with compensated heart disease?
ASA PS 2
What is the ASA status for a patient undergoing surgery to correct an uncomplicated hernia?
ASA PS 3
What is the ASA status for a patient with severe systemic disease?
ASA PS 3
What is the ASA status for a patient undergoing a fracture repair in shock?
ASA PS 3
What is the ASA status for a patient undergoing surgery experiencing dehydration?
ASA PS 4
What is the ASA status for a patient with severe systemic disease that is a constant threat to life?
ASA PS 4
What is the ASA status for a patient with uremia or toxemia?
ASA PS 4
What is the ASA status for a patient with cardiac decompensation?
ASA PS 4
What is the ASA status for a patient with hypovolemia?
ASA PS 4
What is the ASA status for a patient with a high fever?
ASA PS 5
What is the ASA status for a patient that is moribund and not expected to survive one day with/without surgery?
ASA PS 5
What is the ASA status for a patient with terminal malignancy or infection?
hypoventilation, hypercapnia, hypoxemia
What are the 3 primary causes for small animal morbidity related to respiratory issues?
bradycardia, hypotension, cardiac arrhythmias
What are the 3 primary causes for small animal morbidity related to cardiovascular issues?
regurgitation, hypothermia, poor recovery
What are the 3 primary causes for small animal morbidity related to issues other than cardiovascular or respiratory systems?
post-op
What is the most common time of death in small animal surgery?
hypoventilation and hypercapnia, hypoxemia
What are the 3 primary causes for large animal morbidity related to respiratory issues?
horses; they are on their back
What large animal species has a greater issue with hypoxemia under anesthesia? Why?
atelectasis due to the weight of the animal and the GIT pressing on the diaphragm
What contributes to hypoventilation seen in large animals under anesthesia?
bradycardia, hypotension, cardiac arrhythmias
What are the 3 primary causes for large animal morbidity related to cardiovascular issues?
poor recovery related to neuropathy, myopathy, or fractures; post-ax colic
What are the 3 primary causes for large animal morbidity related to issues other than cardiovascular or respiratory systems?
large animals have much greater issues of neuropathy, myopathy, and fracture in recovery
What is the main difference in anesthetic complications between small and large animals?
bradycardia,
tachycardia,
hypotension,
hypertension,
hypocapnia,
hypercapnia,
hypoxemia,
hypothermia,
regurgitation
What is the order of anesthetic complications related to the patient?
bradycardia
What is the most common anesthetic complication related to the patient?
they have high vagal tone
Why are brachycephalics more prone to bradycardia under anesthesia?
eyes, head/neck, thorax, or areas of the GIT
What surgeries are associated with stimulation of the vagal reflex?
increased IC pressure causes bradycardia, hypertension, and irregular respiration
Explain cushing's triad.
alpha-2 agonists and opioids
What are common drug-related causes of bradycardia?
anticholinergics (increases workload on heart; increases HR in the face of vasoconstriction); give antipamezole to reverse
What should NOT be given to correct bradycardia associated with alpha-2 agonists? What should?
second degree AV block
What is the most common arrhythmia associated with alpha 2 agonists?
p wave lacking a corresponding QRS
Describe the ECG of a second degree AV block.
first degree AV block
What is the ECG depicting?
second degree AV block
What is the ECG depicting?
third degree AV block
What is the ECG depicting?
third degree AV block; pacemaker
What AV block cannot be caused by anesthesia? how is it corrected?
sinus arrest
What is the ECG depicting?
anticholinergics
How is sinus arrest treated?
atropine; crosses the placenta and BBB
What anticholinergic should be used in the face of an emergency due to its rapid onset of action?
glycopyrrolate; lasts longer and does not cross the placenta or BBB
What anticholinergic should be used if you need one during a c-section?
atrial standstill
What is the ECG depicting?
hyperkalemia
What is the most common cause of bradyarrhythmias in relation to electrolyte imbalances?
calcium gluconate, insulin with dextrose, sodium bicarbonate, beta 2 adrenergic agonists (albuterol, terbutaline) or loop diuretics
How is atrial standstill treated?
lidocaine or procainamide
How is ventricular tachycardia treated?
decrease inhalant, increase preload with crystalloids/colloids, increase afterload with vasopressors, increase HR with anticholinergics, increase contractility with ionotropes (dobutamine)
How do you treat hypotension?
ketamine, anticholinergics (atropine)
What drugs are associated with tachycardia?
pheochromocytoma, hyperthyroidism, heart disease, hypovolemia
What disease processes are associated with tachycardia?
sympathomimetics- alpha 2 agonists
What drugs are associated with hypertension?
renal failure, pheochromocytoma, cushings' triad
What disease processes are associated with hypertension??
the second one; the end-tidal CO2 is low and RR is higher
Which capnograph is associated with hyperventilation and how can you tell?
obstructed gas flow
What does this capnograph indicate?
obstructed gas flow
What capnograph is said to have a "shark-fin" appearance?
decreased FiO2,
hypoventilation of room air,
alveolar hypoventilation,
diffusion impairment,
shunting,
ventilation-perfusion mismatch
List 6 causes of hypoxemia.
cystic fibrosis,
pneumonia
What are causes of diffusion impairment resulting in hypoxemia?
beta 2 adrenergic agonists like albuterol or terbutaline
What drug class can be given to help combat hypoxemia?
metabolic acidosis, cardiac arrythmias, coagulation alterations
What are secondary effects that can result from hypothermia?
famotidine, metoclopramide, maropitant
What are drugs that can be given to prevent regurgitation?
NO; provide temporary peripheral desensitization that stops when the animal is removed from anesthesia
Do inhalants provide analgesia?
allodynia
Pain with light touch even if it is not in the direct area of damage is known as _____.
decreased inhalant requirements, consistency in stability of anesthesia, MAC reduction, improved cardiovascular and respiratory stability
What are effects on anesthetics that result from providing intra-op analgesics?
Boluses cause toxic side effects when concentration is at highest point and no effect when concentration is at the lowest point. CRI avoids this
Why are CRI preferred to boluses?
significantly greater reduction in dogs than cats, especially with opioids
What is the difference in cats and dogs related to the reduction in MAC seen with the use of intra-op analgesics?
reach the therapeutic level more quickly
Why use a loading dose with a CRI?
context-sensitive half-time
What is the term for a half-life when dealing with a CRI?
they can accumulate and take longer to metabolize
Though they have published context-sensitive half-times (half-lives), there is still a danger with CRI effects. Why?
titrate the dose down to allow for appropriate recovery time
How do you prevent accumulation of drugs on CRI and resulting increased recovery time?
MG of drug= [(drug dose in mg/kg/hr)/ (fluid dose rate in ml/kg/hr)] x Diluent (mL)
What is the CRI formula? (WATCH UNITS)
10 ml/kg/hr
What is the fluid dose rate in the CRI formula?
divide this answer (mg) by the concentration on the bottle (mg/mL) to get the mL of drug
What do you do with the fluid dose rate to determine the number of mL drug that you should add to the bag for CRI?
large animals
Where is TIVA primarily used?
Easy use, cheap, can be used in field ax, no scavenging required, better cardiovascular function than with inhalants, less stress than with inhalants, smoother recovery than with inhalants
What are the advantages of TIVA?
Cumulative effects and poorer recoveries when procedures are >1 hr in duration, difficult to assess depth, requires liver metabolism, IV drug availability may be limited
What are the disadvantages of TIVA?
ketamine
What injectable anesthetic maintains the palpebral reflex?
alpha-2 agonists, ketamine; 20-30 mins
What are short term TIVA drugs? duration of effect?
"triple drip"/"GKX- guaifinensin, ketamine, xylazine
What are long term TIVA drugs? duration of effect?
guaifenesin 500mls, ketamine 500 mls, xylazine 250 mls; at 1-2 ml/kg/hr. Same concentration regardless of size, just alter drip rate
Explain the dosing and rate for the TIVA "triple drip".
respiratory rate; palpebral, tear production, blinking, nystagmus
What is the best way to monitor TIVA anesthetic depth? other methods?
lung procedures, BAL, bronchoscopy
In what situations is TIVA used in small animals?
when the body shunts blood away from a damaged piece of lung because it is not being ventilated so there's no point; that lung is likely dead already anyway
Explain the hypoxic pulmonary vasoconstriction reflex.
they prevent it, causing perfusion to areas of lung that are not being ventilated and causing hypoxia
What is the effect of inhalants on the hypoxic pulmonary vasoconstriction reflex?
preserve the reflex, preventing resulting hypoxia
What is the effect of TIVA on the hypoxic pulmonary vasoconstriction reflex?
the brain likes to have maintained blood flow levels and protects against alterations
Explain blunt cerebral autoregulation.
they prevent it, allowing changes in blood flow to the brain that can be especially detrimental in hypertension
What is the effect of inhalants on blunt cerebral autoregulation?
maintain the autoregulation
What is the effect of TIVA on blunt cerebral autoregulation?
Propofol, alfaxolone, lidocaine, opioids, dexmedetomidine, midazolam, ketamine, local anesthetics
List drugs used in TIVA.
analgesia, muscle relaxation, unconsciousness
What are the goals of anesthesia?
pre-ax, induction, maintenance, recovery
What are the phases of anesthesia?
decrease stress of handling and lead to safer environment for all
What is the benefit of sedating an animal with a premed?
decreases necessary dosages of different drugs, decreases side effects of each drug, allows for a smooth recovery
What is the benefit of using balanced anesthesia in an animal with a premed?
most anesthetics are poor analgesics
What is the benefit of providing analgesia to an animal with a premed?
10-15 minutes prior
What is the time a premed should be administered in relation to induction?
17-50%
What % of small animal patients experience gastro-esophageal reflux?
increase resistance to flow of air in the airway and increase dead space because the diameter of the tube is very small compared to the diameter of the airway
What is the downside to intubating an anesthetized patient?
biggest tube allowed by the trachea placed cranial to the thoracic inlet and just caudal to the incisors
Explain the proper location of the ET tube in an anesthetized small animal
visualizing the tube; condensation in the tube, capnograph, feel air flow through the tube, lung sounds
What is the best way to verify correct intubation? Other methods
0.87
What is the MAC of halothane?
1.3
What is the MAC of isoflurane?
2.3
What is the MAC of sevoflurane?
7.2
What is the MAC of desflurane?
potency increases with solubility
What is the relationship between potency and solubility of inhalants?
potency increases with decreasing MAC
What is the relationship between potency and MAC of inhalants?
temperature, hypoxemia, age, CO2 (?), and other drugs used
What factors alter MAC requirements?
plane 2
What is the target plane of anesthesia?
plane 2
Identify the stage of anesthesia where the palpebral reflex is no longer present.
plane 4 (overdose)
Identify the stage of anesthesia where the jaw tone is lost.
plane 1 and plane 4
Identify the stage of anesthesia where the eyes are located centrally.
plane 2 and plane 3
Identify the stage of anesthesia where the eyes are rotated ventromedially.
plane 4 (overdose)
Identify the stage of anesthesia where the pupil size is consistently large.
plane 2
Identify the stage of anesthesia where the patient may or may not respond physiologically to stimuli.
plane 1
Identify the stage of anesthesia: Your patient has large, centrally located pupils, strong jaw tone, and a present palpebral reflex.
plane 2 or plane 3
Identify the stage of anesthesia: Your patent has medium-sized ventromedially rotated pupils, an absent palpebral reflex, weak jaw tone, and is not responding to physiological stimuli.
plane 2
Identify the stage of anesthesia: Your patent has small, ventromedially rotated pupils, medium jaw-tone, and and is not responding to physiological stimuli.
HR: 50-130,
CRT: <2 sec,
lactate: <2.5 mmol/L
Give the target value for HR, CRT, and lactate levels.
SAP: 90-130 mmHg,
MAP: 60-90 mmHg,
DAP: >50 mmHg
Give the target values for BP (SAP, MAP, and DAP).
SpO2: >95%
EtCO2: 35-45%
Give the target value for SpO2 and EtCO2.
consciousness, ability to support themself, no need for cardio/respiratory support, normal temp
What are factors to look for in a patient that is recovering well?
acepromazine,
benzodiazepines,
dexmedetomidine
What premeds did we discuss that work effectively as sedatives?
opioids
What premeds did we discuss that work effectively as analgesics?
ketamine/benzodiazepines,
propofol, alfaxolone, etomidate, inhalants
What induction agents did we discuss?
aka obesity hyperventilation syndrome; obese individuals tend to have problems breathing leading to decreased O2 and increased CO2 even in the face of actual hyperventilation
What is Pickwickian syndrome?
Better to auscultate at the sternum because there is more sternal contact with the heart and you are able to hear arrhythmias
What is the appropriate place to auscultate a cat?
closure of valves; normal in every animal
What do S1 and S2 heart sounds represent? In what patients can they be heard?
turbulent fill of the ventricles; heart disease patients
What do S3 and S4 heart sounds represent? In what patients can they be heard?
Eyes and a lot of the brain get blood from maxillary artery; this comes very close to the angular process of the mandible. Cortical blindness can occur if the artery is occluded for too long by the mouth being held open under tension
Why can't you use spring-loaded specula in cats during dentals?
doppler devices; it is closer to MAP than SAP
What monitoring equipment is less accurate in cats, and what values does it produce?
no special risk
What is a potential complication with the use of propofol as an induction agent in the cat?
hemolysis and heinz body anemia have been reported, but are not clinically relevant
What is a potential complication with the use of propofol chronically in the cat?
propofol, etomidate, diazepam
What are anesthetics that have been known to cause hemolysis and heinz body anemia in cats when used chronically or in high doses?
poor lung sounds; poor oxygenation, not staying asleep, removing the tube
What is the best way to identify a mucus plug in a feline ET tube? Other methods?
lidocaine; 30-45 seconds
What is commonly used to desensitize the arytenoids in cats prior to intubation? How long does this take to have an effect?
administer muscle relaxants
In the event of a laryngospasm in a cat, what can be done to stop it once it has begun?
10 mmH2O; their lungs are more compliant and you get the same tidal volume with lower pressure
What is the max pressure you should provide on manual respiration in a cat? Why?
in cats the spinal cord extends past the L7/S1 space, more likely that you will inject into the subarachnoid space in the cat on epidural, which is a smaller cavity and will overdose the animal if you give the same amount you intended to use in the epidural space. This has a huge likelihood of causing cranial migration and CNS toxicity
What is the difference in the extent of the spinal cord in dogs and cats? How does this affect epidural administration?
the brain has adapted to higher pressures over time, so providing "normal" BP values under anesthesia is equivalently hypotension to that animal
What is the issue with monitoring BP in a cat with chronic hypertension in regard to cerebral autoregulation?
cats have fewer nephrons, so even small bouts of hypotension can result in kidney disease
What is the issue with monitoring BP in a cat with chronic hypertension in regard to the kidney?
diazepam, ketamine, NSAIDS, sevoflurane
What are drugs that should be used with caution in cats with kidney disease?
Propofol, carprofen, benzyldiazepam, aspirin, acetaminophen, propylene glycol
What are drugs that should be used with caution/not used in cats due to decreased conjugation and glucuronidation capabilities?
alpha 2 agonists and opioids
Which perianesthetic drugs cause vomiting in cats?
etomidate
What drug should not be used in addisonian patients die to its cortisol-suppressive effects?
buprenorphine, ketamine, dexmedetomidine
What drugs can be given as an oral liquid in especially fractious cats?
cats have much higher MAC
What is the difference between the MAC of cats verses that of horses or dogs?
nociception indicates that the sensation is felt but not perceived
What is the difference between nociception and pain?
transduction, transmission, modulation, perception
What are the 4 steps of the pain pathway?
perception
What step of the pain pathway is missing with nociception?
transduction
Term for the production of the pain signal at the beginning; this is the initial stimuli alerting pain fibers.
alpha-delta fibers; myelinated fibers that alert to acute, sharp, cutting pain
What is known as "1st pain" in transduction? describe how it is produced.
c fibers; non myelinated fibers producing aching, throbbing pain
What is known as "2nd pain" in transduction? describe how it is produced.
transmission
Term for sending signal of pain up the pathway from the original location of damage through 1st, 2nd, or 3rd order neurons to the brain.
slows healing: alters glucose levels, clotting time, catecholamines, etc
What is evidence to support providing complete pain control in patients post-op is better than allowing some pain to protect the incision site?
Increased HR and BP, tachypnea, arrhythmias, vasoconstriction, increased RR/ splinting (tensing while breathing), dilated pupils, inappetence, salivation, vomiting, change in bowels, stress leukogram
What objective data can be used to assess pain?
many of the data points altered in pain will also be altered with stress or excitement
What is the confounding factor in using objective data to diagnose pain?
subjective assessment
What is the most accurate method of determining pain level in patients?
it forces you to look at and consider this issue, making it easier to monitor through time
What is the main benefit of recording a pain score on every patient?
when a pathway has been triggered so often that any stimulus in the pathway is interpreted as pain even if this is not appropriate
What is wind-up pain?
nociceptive, inflammatory, neuropathic, functional
What are the 4 potential sources of pain sensation?
skin, muscle, joints, tendons, or bones; often well localized and involves nociceptors
What comprises the regions of somatic pain? Describe this pain.
involves hollow organs and smooth muscle nociceptors sensitive to stretching, hypoxia, and inflammation; often pain is referred, diffuse, vague, and poorly localized
What comprises the regions of visceral pain? Describe this pain.
visceral
Which type of pain is often associated with autonomic symptoms (pallor, sweating, nausea, alteration in HR or BP)?
Alprazolam, clomipramine, trazadone; don't sedate the animal to the point where it can't tell you it is painful
What drugs may be used as anxiolytics to help control pain? What must you be careful to avoid?
horses; 1%
What species has the highest anesthetic death rate? What is this rate?
20-50%
What percentage of anesthetic deaths in horses are related to cardiovascular issues?
4-25%
What percentage of anesthetic deaths in horses are related to respiratory issues?
hypoxemia, v/q mismatch, upper-airway obstruction post-extubation
What respiratory issues contribute to the high mortality rate of horses under anesthesia?
7-14%
What percentage of anesthetic deaths in horses are related to myopathy issues?
hypotension; MAP >70 at all times
What factor is responsible for the high incidence of anesthetic death in horses? How can it be prevented?
13%
What percentage of anesthetic deaths in horses are related to abdominal complications?
4-5%
What percentage of anesthetic deaths in horses are related to CNS disease?
0%
What is the survival rate of horses with myelomalacia?
emergency, fractures
What are surgery types that increase risk of anesthetic death in horses?
between 1pm -6 am on weekends
What time/day parameters increase risk of anesthetic death in horses?
>5 years
What age range increase risk of anesthetic death in horses?
anything over 120 mins
What anesthesia duration parameters increase risk of anesthetic death in horses?
2x risk
By what % does the risk of anesthetic death increase in horses undergoing surgery between 120 and 180 mins long?
6x risk
By what % does the risk of anesthetic death increase in horses undergoing surgery for over 240 mins?
if they will be placed in dorsal recumbency
In what situation should horses be fasted prior to anesthesia?
decreased weight on the diaphragm
What are advantages of fasting a horse prior to anesthesia?
promotes ileus, alters microbiota, increased risk of ulcers
What are disadvantages of fasting a horse prior to anesthesia?
horse may fall, horse moving and preventing the surgery from occurring, personal safety, edema of the nasal passages
What are concerns in performing standing surgery in the horse?
head at the level of the carpus, decreased menace, standing ataxia/truncal sway
How do you know a horse undergoing a standing procedure is adequately sedated?
give 50 mg (1/2 ml) ketamine every 20-30 mins
Explain the "standing stun" technique used in horses.
ketamine and diazepam/midazolam OR guafenosin
What agents are most commonly used for induction in horses not undergoing standing procedures?
ventromedially the ENTIRE way
How should you angle a tube when nasally intubating a horse?
recovery
What is the most dangerous, problematic, and unpredictable phase of equine anesthesia?
transition, first movement, movement to sternal, first attempt to stand, initial standing, completed recovery
What are the phases of anesthetic recovery in the horse?
isoflurane
What inhalant has the longest recovery time in the horse?
beta 2 adrenergic agonists like albuterol or terbutaline
What drug may cause profuse sweating in the horse?