Chapter 22: Anesthetic Practice for Existing Conditions Flashcards
Describe the 5 ASA grades
What is the rate of anaesthetic-related death in animals?
1 : 500 (0.002%) to 1:1000 (0.001%)
Humans 1:10,000
What medications are contraindicated in animals with cardiac disease?
- alpha-2 agonists
- Acepromazine should only be used if they can tolerate vasodilation
- Caution with ketamine in HCM
- Propofol/alfaxalone should be used cautiously due to vasodilation. Etomidate is ideal.
- Some animals wont be able to tolerate gas vasodilation
What medications are contradicted in the face of thyroid disease?
- Ketamine due to potential cardiomyopathy and possibility of thyroid storm
- Avoid NSAIDs and maintain normal/slightly elevated BP due to potential for underlying renal disease
- May have cardiomyopathy
What is hypoxic pulmonary vasoconstriction?
A compensatory mechanism that results in vasoconstriction of the blood flow to the alveoli that do not have an adequate oxygen supply. Helps to balance a V/Q mismatch in awake patients.
Inhalant anesthetic agents impair or eliminate this compensatory mechanism causing V/Q mismatch to worsen in the anesthetized patient
What are some potential benefits of ketamine when used on patients with airway disease?
- Causes bronchodilation (good for allergic airway disease)
- Maintains the respiratory center sensitivity to PaCO2
- Maintains respiration making it a useful induction agent
What considerations should be made when making a plan for a patient with liver disease?
What drugs are good for liver patients?
- Often require lower doses of drugs if hypoalbuminemic as many anesthetic drugs are highly protein bound to albumin
- Propofol has extrahepatic metabolism and so is a good choice, as is remifentanyl (plasma esterase)
- Inhalants undergo very little hepatic metabolism and are also a good choice
List some drugs which are renally excreted and therefore effects may be prolonged in patients with renal disease:
- Ketamine
- benzodiazepines
- opioids
- acepromazine
What anesthetics should be avoided in renal disease?
Specifically inhalants?
- Ketamine
- Sevoflurane (Compound A is nephrotoxic)
- Epidural contraindicated due to potential coagulopathies in severe uremia cases
What are the main risks after reliving a urinary obstruction?
- Post-obstructive diuresis
- Dialysis disequilibrium - seen if BUN drops rapidly causing a decrease in serum osmolality and associated fluid shifts resulting in cerebral edema
What is the maximal allowable pressure during laparoscopy?
At what pressure is there an association with anuria and acute renal failure?
-14cmH20 maximum allowable
- 25cmH2O anuria, AKI
What patient positioning is used for laparoscopic surgeries?
Trendelenburg positioning (head-down)
What is the only anesthetic drug which has been shown to adversely effect neonate survival in C-sections?
xylazine
For lumbosacral epidurals, what volume is appropriate for the hind limbs? For abdominal/thoracic?
- 0.2ml/kg for hind limbs
- 0.3ml/kg for abdomen/thorax coverage
What considerations need to be made when anesthetizing for an ophtho procedure?
- Maintaining central eye position (low dose neuromuscular blockade)
- Avoiding spikes in IOP (can be caused by propofol and ketamine)
