Pyometra anaesthesia

Question 1

What premedication should you use for pyometra surgeries?

Answer 1

ASA III-V eg, SIRS, sepsis
* As animals become more compromised avoid
◦ NSAIDs
◦ Alpha 2 agonists
◦ Acepromazine
* Risk communicated to owner?
* Oxygen & IV access - continue
* Analgesia
* IV fluid resuscitation/challenges

Opioids
* Methadone (IM or slow IV) or
* Fentanyl (slow IV) if you get high HR or BP
and
* Consider Lidocaine bolus then CRI

Question 2

What should you use to induce for pyometra surgery?

Answer 2

• As animals become more compromised always continue to administer oxygen during induction
• Administer drugs slowly as ‘vein to brain’ time has increased with low cardiac outputs
• Titrate to effect
• Options
  ◦ Propofol or alfaxalone (low end of dose range)
  ◦ Propofol or alfaxalone then benzodiazepine then more propofol or alfaxalone
  ‣ (ie co-induction, theory is it might reduce total dose of propofol or alfaxalone…..)
  ◦ Ketamine and benzodiazepine

Question 3

How should you maintain anaesthesia in a pyometra surgery?

Answer 3

• Measure ET tubes, reduce dead space, inflate cuff with care, secure well (tie to patient)
• Use lowest % of sevoflurane or isoflurane (why?)
  ◦ they drop CO
• Supplement with CRI (boli), what drugs can be used?
  ◦ methadone in premed
• Use local anaesthesia where possible (topical, PNB, into abdomen or thorax, wounds, incisions)
  ◦ epidural
  ◦ splash block (drop some in once it is open)
  ◦ line block (skin of the abdomen and linea alba)
  ◦ tap block
• Aim to reduce MAC of volatile agent

Question 4

How should you react to hypotension in pyometra surgery?

Answer 4

Hypotensionis a common complication during anaesthesia and is defined as BP values of systolic <80–90 mm Hg, mean <60–70 mm Hg, and diastolic <40 mm Hg
* Switch down the volatile agent and consider PIVA – see if this works
* Try an IV bolus of crystalloid (5-20ml/Kg) occasionally colloids are used – see if this works
* If the animal is bradycardic too? Administer anticholinergic (atropine/glycopyrrolate)
* Can then consider an inotrope or vasoconstrictor
* Don’t forget hypothermia/ hypoglycaemia and electrolyte imbalances too