Anaesthesia quiz Flashcards
Which opioid can antagonise the effects of fentanyl?
Butorphanol.
Butorphanol is a kappa agonist and a mu antagonist and thus can interfere with activity of fentanyl and other mu receptor agonists. This effect can last much longer than the clinical sedative and analgesic effects of butorphanol
What opioid that should be avoided in dogs with oesophageal foreign body?
Morphine.
Morphine should be avoided due to the risk of vomiting which is detrimental in a patient with oesophageal foreign body as vomiting may lead to increased trauma if foreign body such as a bone is stuck in the oeophagous.
Vomiting is also contra-indicated if animals have GDV, intracranial disease and bleeding disorders.
What is the opioid agent that has been reported to cause the most hyperthermia in cats?
All opioids can alter thermoregulatory thresholds, however buprenorphine has the longest effect of all mentioned opioids and has been reported to cause severe hyperthermia in cats. It is not reported in dogs.
What are the most common adverse effect of systemic administration of opioids on the cardiovascular system
Bradycardia and hypotension.
Typically opioids increase parasympathetic activity and lead to decrease HR. If severe this will result in decreased BP. The exemption is pethidine which has anti-muscarinic effects and can increase HR and BP. Furthermore, if histamine release is stimulated by release of Morphine, this will decrease BP and may result in compensatory increase in heart rate.
What are two commonly used agents that are NMDA receptor antagonists?
Ketamine has NMDA antagonist effects at sub-anaesthetic doses. It is a useful agent for administration as a low dose infusion in animals with increased sensitivity to pain.
Methadone is a full mu agonist and NMDA antagonist. this makes it a useful opioid to use in patients with increased sensitivity to pain, tolerance to opioids and as a rescue analgesic agent when analgesia associated with other analgesics is inadequate.
Lignocaine administered as a intravenous infusion is a good analgesic agent during GIT surgery, why?
Lignocaine is a prokinetic
What is the recommended dosing regimen for perioperative use of carprofen in cats?
One dose only.
Carprofen is registered for a single dose only in cats due to risk of kidney injury associated with multiple dosing. In contrast Meloxicam is registered for once a day for three days at doses used for perioperative analgesia. Lower doses of meloxicam have been used chronically in cats with osteoarthritis without apparent increased risk of kidney damage
A dog requires anaesthesia for a lump removal. The dog has been receiving antidepressant to assist with chronic neuropathic pain. What agent that should be avoided due to the potential for drug interactions.
Tramadol is a serotonin uptake inhibitor that increases serotonin levels within CNS. If tramadol is used with other agents that increase serotonin levels serotonin toxicity can result. This results in hyperthermia and seizures and can be fatal.
What opioid that is considered to have the best transmucosal uptake in cats?
Buprenorphine is believed to be well absorbed across the oral mucous membranes. It does not need to be swallowed.
Epidural administration of bupivacaine is contraindicated under what 4 conditions?
Skin infection, sepsis, hypovolaemia, coagulopathy
Select the two mu receptor agonists that are associated with histamine release especially after IV administration
Pethidine + Morphine.
Pethidine commonly causes histamine release when administered IV, thus this route of administration is generally avoided for Pethidine
Select the opioid that is most commonly associated with panting in conscious animals
Methadone
Opioids mediate panting by altering the thermoregulatory threshold. As a result dogs will pant to cool themselves even when body temperature is normal. this is most commonly seen with methadone and fentanyl.
Metabolism of opioids is decreased in animals with reduced liver function. Select TWO changes in administration required to prevent accumulation of repeated doses of opioids.
Use of lower doses, especially when using IV infusions of drugs like fentanyl, will also help reduce accumulation of opioids when their metabolism is reduced. Furthermore, if liver disease has resulted in reduced serum albumen, lower doses are required if using an opioid that has a high level of protein binding e.g. fentanyl
Use metabolism is decreased in animals with reduced live function the duration of effect is longer and thus increased interval between doses is required.
Select two opioids which can not be reversed with nalaxone
Butorphanol is a mu receptor antagonist and kappa receptor agonist and thus can not be reversed using naloxone which is a mu receptor antagonist only. However, adverse effects associated with drug administration have a ceiling effect, severe decreases in HR and ventilation are less likely
Buprenorphine is a partial mu antagonist that binds very tightly to the mu receptor, as a result it is very difficult to reverse. However, adverse effects associated with drug administration have a ceiling effect, severe decreases in HR and ventilation are less likely
When using a circle breathing system (=rebreathing system) a higher oxygen flow rate is used initially. Why?
To prevent excessive dilution of inspired anaesthetic gases (gases in the circle) by expired gases
A co-axial bain is selected for use in an 8 kg pug. What is the minimum oxygen flow rate that should be used in this dog.
2.4L/min
A paediatric circle system can be used in animals < 10 kg. Select the reason/s why this is possible
The Y piece has a smaller dead space which minimises rebreathing.
The new concentration of inhalation agent is reached quicker after changing the vaporizer setting due to the smaller volume of the breathing system. There is still some dilution within the space of the sodalime canister; however the volume is reduced by using narrower tubes and small rebreathing bag
Duration of action of which induction agents are significantly reduced in animals receiving phenobarbitone or corticosteroids increasing risk of sudden wakening
Propofol + Alfaxalone
Select the one most commonly associated with increased HR and blood pressure in normal animals
Buprenorphine
Ketamine
Medetomidine
ACP
In animals with a normal sympathetic nervous system, ketamine stimulates release of catecholamines that lead to increased HR and BP. Please note that in animals with depleted or immature sympathetic nervous systems, the direct depressant effects of ketamine will predominate leading to decreased BP.
Alfaxalone is the only agent that has not been reported to cause arrhythmias - True or False?
true
Of commonly used induction agents, duration of clinical effect of which drug, is not altered in animals with reduced hepatic function
propofol
Ketamine should be used carefully in animals with kidney disease especially cats. Why?
In cats, 50 % of ketamine is excreted unchanged by kidneys
Select the induction agent most commonly associated with hypotension directly after induction
Thiopentone
Select the induction agent that increases intracranial cerebral metabolism and thus can increase intracranial pressure
Ketamine increases metabolism of the brain which leads to increased cerebral blood flow, and this increase in blood volume causes increased ICP
Select the induction agent that is most commonly associated with agitated recoveries in lightly sedated healthy dogs
Alfaxalone
