Lecture 13 Special Considerations in Anesthesia Part 2

Question 1

What are causes of —Acute post-renal disease

Answer 1

1. —Ruptured bladder dog
2. —Feline lower urinary tract disease
3. —Ruptured bladder foal
4. —‘blocked’ ruminant

Question 2

Acute post-renal disease metabolic abnormalities

Answer 2

1. —Dehydration
2. —Metabolic acidosis
3. —Uremia (↑BUN, creatinine)
4. —↑ K+*
5. —↓ Na++
6. —↓ Cl-
7. —Respiratory compromise
   
   • —Or respiratory alkalosis

Question 3

What does —↑ K+ do to heart?

Answer 3

bradycardia

Question 4

What are values that you want to fix before surgery

Answer 4

1. —Correct dehydration, hyperkalemia, acidosis, Na, Cl
2. —+/- drain fluid from abdomen slowly (foals, dogs)

Question 5

Pre-op preparation for Acute post-renal disease

Answer 5

1. —↓ serum potassium levels
   
   • —K+ free fluids - .9%NaCl
   • —Glucose +/- insulin – shifts K+ intra-cellularly
     
     • —5% dextrose (effects in 15-30min), .5-1 U/kg insulin
   • —Sodium bicarb
2. —Stabilize myocardium
   
   • —.5mg/kg IV slowly 10% Ca gluconate
     
     • reestablishes depolarziation threshold in the heart

Question 6

What do you want to do during anesthesia for Acute post-renal disease

Answer 6

1. —Avoid drugs that are excreted unchanged by the kidney
   
   • —Ketamine in cats
2. —IPPV because they normally can have K+ and H+ shifts if PACO2 increases and get more K+

Question 7

What do you want to do during anesthesia for chronic renal disease

Answer 7

1. —Maintain renal blood flow
   
   • —Avoid hypotension, treat aggressively
2. —Fluid administration
   
   • —Higher than normal rates to promote diuresis
   • —Ensure absence of severe cardiac disease, congestive heart failure, pulmonary edema, anuria
3. —Avoid drugs excreted unchanged by the kidney or that have active metabolites
   
   • ketamine in cats
4. —Caution with NSAIDS

Question 8

How do you want to get ready for —Diabetes Mellitus patient anesthesia

Answer 8

• —Blood glucose regulation prior to anesthesia
• —Stress/fasting disrupt BG regulation
• —Schedule for early morning
• —Check BG in a.m., give ½ insulin dose
• —Monitor BG intra-op
• —Quick recovery to return to normal eating patterns

Question 9

Why can Canine Hypothyroidism be bad for anesthesia

Answer 9

1. —↓ metabolic rate
   
   • —↓ drug metabolism
   • —Hypothermia
   • —Delayed recovery
2. —Obese
   
   • —Hypoventilation => IPPV
3. —Peripheral Neuropathy => laryngeal paralysis
   
   • —See BAOS pre-op & induction management
4. —Replacement and re-check thyroid levels pre-op

Question 10

Considerations for Hyperadrenocorticism – Cushing’s dogs

Answer 10

1. —Weak muscles => IPPV
2. —Hypercoagulable
3. —↓ wound healing

Question 11

What do you want to avoid with patients with Ocular Disease

Answer 11

—Avoid increasing IOP

1. Dont use
   
   • —Ketamine, tiletamine, etomidate
2. —Avoid vomiting
   
   • Maropitant 1 hr before opioid
3. —Avoid coughing/gagging at intubation
   
   • —Deep anesthesia, Lidocaine adjunct 1-2mg/kg IV dogs
4. —Avoid head down position/venous congestion
5. —Avoid hypercarbia & hypoxemia

Question 12

How do you centralize eye position for ocular surgery

Answer 12

1. —Neuromuscular Blockers
2. —IPPV

—

Question 13

1. What is the —Oculocardiac Reflex
2. What does it cause
3. How to treat

Answer 13

1. —Traction or pressure on eye
2. —Bradycardia, AV block, asystole
3. —Anti-cholinergics: Atropine, Glycopyrrolate

Question 14

How do you want patients with Ocular Surgery to recover

Answer 14

1. —Adequate pre-medication
2. —Sedation for recovery
3. —Eye protection

Question 15

General Considerations for Geriatric Patients

Answer 15

1. ↓ organ reserve,
2. ↓ adaptation,
3. failure of homeostatsis

Question 16

1. What are the CNS concerns in Geriatric patients
2. Cardiovascular?

Answer 16

1. —CNS:
   
   • loss of neurons,
   • ↓ MAC,
   • prone to dysphoria,
   • emergence delerium
2. —CVS:
   
   • SV dependent for CO,
   • More prone to pre-op volume depletion

Question 17

1. What are the renal concerns in Geriatric patients
2. Hepatic
3. Orthopedic

Answer 17

1. —Renal:
   
   • ↓ GFR, renal bf,
   • ADH => susceptible to post-op renal failure, fluid overload
2. —Hepatic:
   
   • ↓ drug clearance
3. —Orthopedic:
   
   • osteoarthritis so positioning is important

Question 18

Drugs used for geriatric patients

Answer 18

1. —Opioids
   
   • —Analgesia, sedation, induction agent/inhalant sparing
2. —Benzodiazepines
   
   • —Sedative in old/debilitated pts
3. —Judicious use of anti-cholingergics

Question 19

1. Neonatal/Pediatric Patients liver concerns
2. CNS

Answer 19

1. —Liver:
   
   • ↓metabolism,
   • hypoglycemia,
   • ↓ albumin
2. —CNS:
   
   • ↑ BBB permeability,
   • SNS immature

Question 20

1. Neonatal/Pediatric Patients cardiovascular concerns
2. Respiratory
3. Temperature

Answer 20

1. —CV:
   
   • HR dependent for CO
2. —Resp:
   
   • High metabolic rate/RR, easily fatigued
3. —Poor thermoregulation

Question 21

Neonatal/Pediatric-General general strategies for drugs

Answer 21

1. —Lower doses ( ↓ protein binding, ↑ BBB permeability)
2. —Drugs not metabolized by liver or reversible
   
   • —Inhalants, opioids, benzodiazepines, propofol
3. —+/- Anticholinergics – maintain HR

Question 22

Neonatal/Pediatric-General Strategies for monitoring

Answer 22

• —Hypotension
• —Monitor/supplement glucose in IV fluids
• —Monitor temp/active pt warming

Question 23

1. Common disease that Neonatal Foals could have
2. drugs to avoid?

Answer 23

1. —Patent ductus arteriosis up to 6 days old
2. —Avoid alpha-2 agonists

Question 24

1. Neonatal Foals premedication
2. Inhalant used

Answer 24

1. —+/- premedication with benzodiazepine, butorphanol
2. —Inhalant induction with Isoflurane or Sevoflurane

Question 25

1. At what age can you use xylazine as a pre-med for neonatal foals
2. What about total injectable induction?

Answer 25

1. —2 weeks xylazine pre-med OK
2. —> 4 weeks injectable induction