1
Q
T or F: Dogs being treated with ACE inhibitors and diuretics for CHF can be anesthetized
A
True; animals with untreated CHF should not be anesthetized
2
Q
What are you hemodynamic goals for anesthetizing patients with mitral valve regurgitation?
A
- Slight reduction in preload may reduce regurgitant flow
- Avoid acute increases in afterload—> Vasodilators/most anesthetics reduce afterload
- Maintain contractility
- HR can be increased slightly; avoid bradycardia b/c results in long systole and worsens regurg!
- Rhythm: maintain sinus rhythm
- Avoid severe tachycardia and hypotension
3
Q
What are your anesthetic goals for a patient with MR?
A
- Do not fluid overload patient (no boluses); Should receive lower Na fluids (2.5% Dextrose + half strength LRS) at lower rate
- avoid sinus bradycardia - don’t be afraid to use anticholinergics
- maintain myocardial contractility, tx hypotension using beta1 agonist (dobutamine, dopamine)
- slight vasodilation is acceptable, avoid peripheral vasoconstriction —> don’t use alpha 2’s
- minimize excitement - increased catecholamine release may cause vasoconstriction
4
Q
What are some anesthetic considerations for pre-medding a patient with MR?
A
- Ace: low dose, will reduce afterload and provide sedation/minimize catecholamine-induced arrhythmias
- Opioids: indicated for painful procedure and maintain contractility; however, may cause sinus bradycardia so can add anticholinergic to premed protocol if high dose used
- Benzos: produce minimal cardiopulmonary depression, can cause paradoxical excitement, so should be avoided in dogs that are not depressed
5
Q
What are some anesthetic considerations for induction of a patient with MR?
A
- Propofol: causes some periph vasodilation, but can depress myocardial contractility, should be given slowly, can add in a benzo
- Alfaxalone: should be given slowly over 60 seconds, same CV effects as prop
- Ket-diazepam or Ket-midaz: causes transient sinus tachycardia, will increase BP and CO
- Etomidate: most heart-friendly; maintains MAP, HR, and CO; however, rough induction (gagging, myoclonus); indicated in patients w/ enlarged heart and show CHF signs
- Neuroleptanalgesia (diazepam/hydro or diazepam/fentanyl): maintains myocardial function, bradycardia may occur, poor quality induction in non-depressed patients
6
Q
Which drugs should be avoided in patients with MR?
A
- Xylazine
- Medetomidine
- Dexmed
- Phenylephrine (vasoconstrictor)
7
Q
What should be used for maintenance in MR patients?
A
Inhalants; either Iso or Sevo
8
Q
What are the hemodynamic goals for patients with HCM?
A
- Maintain preload in cats without CHF
- Afterload should be increased, if possible
- Myocardial depression is preferred
- HR should be within normal range; avoid sinus tachycardia, as it can worsen the LV outflow obstruction
- Maintain sinus rhythm
- Avoid severe tachycardia and hypotension
9
Q
What are some anesthetic considerations you should have in a patient with HCM?
A
- Adequate diastolic filling can be accomplished by large ventricular volume and sinus rhythm (don’t decrease pre/afterload)
- Ketamine should be avoided b/c it increases contractility and HR, as well as myocardial oxygen demand
- Control dyrhythmias prior to pre-medding
- Minimize stress and excitement b/c of catecholamine release that will increase HR and contractility
- Beta and Ca channel blockers that patient is being treated with should be maintained up until the day of anesthesia
10
Q
What are the recommended pre-meds for patients with HCM?
A
- Opioids: minimal effects on myocardial contractility, preload or afterload; may cause sinus bradycardia, can give w/ glycopyrrolate (not atropine) - less sinus tachycardia
- Benzos: minimal cardiopulm depression, can be given w/ induction agent IV to minimize risk of excitation
- Dexmed or medetomidine: shown to eliminate outflow tract obstruction, dexmed can be used for chemical restraint
11
Q
Which pre-med agent is contraindicated for use in cats with HCM?
A
Ace
12
Q
What are the recommended induction agents for patients with HCM?
A
- Propofol: if etomidate not available, used in combo w/ benzo to reduce peripheral vasodilation
- Etomidate: most heart-friendly agent; best choice if available
- Neuroleptanalgesia: maintain myocardial function, anticholinergic can be added to combat bradycardia, should only be used in HCM cats that are very depressed
13
Q
What method of induction should be avoided in HCM cats?
A
Mask induction with sevo or iso b/c of the stress and excitement it causes
14
Q
What drugs should be avoided in cats with HCM?
A
- High to moderate doses of ace (pronounced vasodilation)
- Ketamine (increases ketamine and contractility)
- Atropine (increases heart rate markedly)
- Thiopental (arrhythmogenic)
15
Q
What agents are used for maintenance in an HCM cat?
A
- Iso or sevo
- Phenylephrine in cats that develop hypotension - alpha agonist that increases peripheral resistance
- Dobutamine/dopamine should be avoided
16
Q
What are the hemodynamic goals for patients with DCM?
A
- Maintain or reduce preload depending upon severity
- Avoid increases in afterload
- Maintain or increase contractility
- Maintain normal HR
- Control dysthymias
- Do not increase myocardial oxygen requirement by avoiding tachycardia and hypotension
17
Q
What are possible sequela of CKD to make sure are managed accordingly prior to anesthesia?
A
- Change in BBB leading to drug sensitivity
- Hypovolemia and dehydration
- Metabolic acidosis
- HyperK
- HyperMg
- HypoCa
- Anemia
- Hypertension but reduced cardiac reserve
- Susceptibility to vagal-induced bradycardia
18
Q
What are some anesthetic considerations you should have when anesthetizing a patient with CKD?
A
- The kidney’s high metabolic rate makes it prone to hypoxemia and hypotension
- Anesthesia works on the RAAS to reduce renal blood flow and redirect away from cortex
- also causes reduced GFR and renal blood flow —> light planes of anesthesia preserve renal autoregulation
- minimize stress/excitement
19
Q
What are your anesthetic goals in a patient with CKD?
A
- Maintain renal blood flow
- Avoid hypovolemia
- Avoid renal vasoconstriction
20
Q
What are the recommended premeds for a CKD patient?
A
- Anticholinergics: no significant effect on renal function, must be given to patients w/ high vagal tone
- Ace: may minimized sympathetic stimulation, can produce hypotension at high doses but low doses are renoprotective
- Benzos: no renal effects, minimal cardiopulm effects
- Opioids: no direct effect on kidneys, antidiuretic effect
21
Q
Why should alpha 2s be avoided in CKD patients?
A
Because they will cause short-term glucosuria and polyuria, and they can cause peripheral vasoconstriction and marked reduction of CO
22
Q
Which drugs should be used for induction of a patient with CKD?
A
- Propofol: no direct kidney effects, though can cause hypotension, so give slow and with pre-med
- Thiopental: decreases renal blood flow and GFR in proportion to decrease in BP, can minimize hypotensive effect if given slowly, however, propofol is preferred b/c is more quickly metabolized
- Etomidate: minimal CV effects, hemolysis risk is a concern in anemic patients
- Neuroleptanalgesia: fluid therapy is a must d/t antidiuretic effects
23
Q
Why are dissociatives, such as ketamine and tiletamine, not recommended for induction agents in patients with CKD?
A
Because they cause sympathetic stimulation, which causes vasoconstriction, and in turn, decreased renal blood flow; also has prolonged effect in cats b/c is almost exclusively excreted by kidneys
24
Q
Maintenance with inhalants, such as sevo and iso, is recommended over injectables in CKD patients..why?
A
- Excretion is not dependent on kidneys
- recovery is faster
- high concentration of oxygen and ventilation can be supported
25
What drugs should be avoided in CKD patients?
* NSAIDs
* Alpha 2s
* Ketamine (cats)
* Telazol (cats)
26
What are important monitoring principles for anesthetic patients with CKD?
* Blood pressure - manage hypotension by decreasing vaporizer setting, give fluid boluses, and administering positive inotropes (dobutamine preferred)
* **Most important factor = fluid administration**
* ****high rate (20 ml/kg/hr) of IV crystalloids should be administered in patients that do not have CHF, pulm edema or are anuric
* can initiate active diuresis in those with inadequate urine output using furosemide or mannitol
27
What are you anesthetic considerations for a patient with diabetes mellitus?
* Pre-anesthetic bloodwork should include: fasting BG, ketones, serum electrolytes, BUN, hepatic enzyme levels, creatinine, and acid-base values
* gentle handling and sending patient home ASAP after procedure
* shorter fasting times
* well-regulated at home might become hyperglycemic at the hospital due to stress
28
What are your anesthetic goals for a patient with DM?
* Prevent hypoglycemia
* Maintain fluid and electrolyte balance
* Control severe hyperglycemia and prevent ketoacidosis
29
What are some good choices for pre-meds in a patient with DM?
* Low dose Ace
* Benzos
* Opioids: when added to either ace or benzos
30
What are good choices for induction agents for patients with DM?
* Propofol: **may be best choice b/c short acting** and doesn’t have “hangover effect”
* Alfaxolone: rapid clearance/shorter recovery time
* Thiopental: may cause further increase in liver enzyme levels
* Etomidate
* Neuroleptanalgesia: only in depressed patients; not as good as prop/alfaxolone
31
What agents should be used for maintenance in DM patients?
Iso or sevo; though sevo has a quicker recovery time
32
What drugs should be avoided in patients with DM?
* Alpha 2’s (hyperglycemia and hypoinsulinemia)
* Dissociatives (mild hyperglycemia due to sympathetic stim)
* Mask induction (stress leading to sympathetic stim)
33
What are some important monitoring principles in patients with DM?
* BG levels should be checked every hour or 30 minutes in unstable patients
* if \>300 mg/dL, regular insulin should be given
* if \<100 mg/dL, increase dextrose infusion rate or bolus 50% dextrose
* **Hypoglycemia is more life threatening during anesthesia than hyperglycemia**
* Oral feeding and routine insulin therapy should resume if possible right after recovery
34
What are some important anesthetic considerations for patients with hepatic insufficiency?
* May be hypoglycemic, so BG should be monitored
* May be hypoproteinemic, so will be more active (free) form of anesthetic drugs present
* Hypoalbuminemia may have decreased colloid oncotic pressure, so should use colloids (not crystalloids) for patients with albumin levels \< 2.0
* Run coag panel if patient shows evidence of bleeding tendencies
* Anesthetic agents will have prolonged effects, so drugs that **are reversible, have minimal effect on hepatic blood flow, and have a short duration of action are preferable**
35
What are you anesthetic goals in patients with hepatic insufficiency?
* Maintain blood flow to the liver
* Maintain arterial blood pressure above 60 mmHg
* Maintain eucapnia and prevent hypoxemia
36
What are the pre med recommendations for patients with hepatic insufficiency?
* Benzos
* Opioids: reversible, minimal CV effects
37
What pre-med agents should be avoided in patients with hepatic dysfunction?
* Ace: longest duration of action and hepatic dysfunction already causes increased free concentration of drug
* Alpha 2s: reduce CO, vasoconstriction, sinus bradycardia, and hypotension (reduces blood flow to liver)
38
What are the recommended induction agents to be used in patients with hepatic insufficiency?
* Propofol: has extrahepatic metabolism as well, rapidly eliminated (except in cats)
* Thiopental: hypoalbuminemia will result in more active form
* Dissociatives: low doses are fine, except in patients showing CNS signs
* Etomidate
* Neuroleptanalgesia
39
What drugs should be used with caution in patients with hepatic insufficiency?
* Ace
* Alpha 2s
* Ketamine
* Thiopental
40
What are some important monitoring considerations in anesthetic patients with hepatic insufficiency?
* BP should be monitored and colloids and positive inotropes should be used if needed
* Should receive high concentration of O2
* Eucapnia should be maintained, as hypoventilation will decr hepatic perfusion
* BG levels should be checked at the end of anesthesia and hours into recovery
* Hypothermia can further prolong the already longer effects
Clinical Anesthesia
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