Anaesthesia

Question 1

What were the findings of Pratt et al (2019 EVJ) WRT TIVA with ket, medetomidine and either midazolam or GGE CRIs?

Answer 1

1. Midazolam was a suitable alternative to guaifenesin when co-infused with ketamine and medetomidine to maintain anaesthesia in young horses undergoing noninvasive procedures. Both infusions produce a clinically comparable quality of anaesthesia
2. Both infusions provided a similar quality of maintenance anaesthesia & rx in minimal haemodynamic depression, mild respiratory depression and clinically acceptable blood oxygenation.
3. Recovery from anaesthesia was of a better quality following an infusion of ketamine– medetomidine–midazolam combo vs GGE; although no major events in either group

Question 2

What is vatinoxan and what is the potential clinical benefit?

Answer 2

Peripherally acting α2 ANTAGONIST

Potential to decrease unwanted peripheral side effects of α2s (hypertension, reflex bradycardia, later hypotension, decr. GI motility, incr. glucose), without having a deleterious effect on centrally mediated α2 agonist mediated sedation and analgesia

In contrast to atipamezole or yohimbine which will reverse the central (sedative) effects as well as peripheral

Question 3

What was the main finding(s) of Tapio et al (2019 EVJ) using vatinoxan with medetomidine CRI for standing sedation

Question 4

Potential adverse effects of systemic morphine administration

Mechanism of action

Answer 4

Adverse effects incl. excitement, ↓ GI motility, ↓ faecal output & colic

Anecdotally, cases of hyperphagia and severe gastric impactions, sometimes leading to gastric rupture have been described

MOA is central and peripheral full µ agonism

Question 5

Findings of Tessier et al (2019 EVJ) re systemic morphine and GI side effects

Answer 5

Administered at 0.1mg/kg IV q4hr for 3 doses

1. Evidence of decr. GI motility (↓ GI bobo and ↓ faecal weight/output) with ↑VFI and water consump & gastric distension
2. Gastric distension was cumulative w repeated doses
3. GI bobo and no of contractions of duodenum, caecum and ventral colons was ↓er
4. Effects were reversible; returned to normal by 16hr post last dose (this was the 1st measurement so couldve normalised before then)
5. No excitement or marked abdo pain in any subject

Question 6

What are the cardiovascular side effects of alpha-2 agonists?

Answer 6

Initially - peripheral vasoconstriction and subsequent baroreceptor-mediated reflex bradycardia and bradyarrhythmias (e.g. second degree AV block) with a profound reduction in cardiac output

Subsequent vasodilation accompanied by hypotension may also be observed