Francesca Beorby, Head Veterinary Nurse at Putlands Veterinary Centre, has performed a clinical audit which has revealed that neutering patients premedicated with medetomidine and methadone were significantly less likely to become hypotensive than when ACP and methadone were used.

Francesca's initiative was recognised with a RCVS Knowledge ‘Highly Commended’ status at its 2024 awards.

The idea for the audit came about after Francesca noticed a trend for patients to become hypotensive during anaesthesia for routine feline neutering and need additional treatment.

CVS says clinical evidence suggests a minimum value of 60mmHg for perfusion of vital organs such as the brain, heart and kidneys. 

So a clinical audit was undertaken to look at perioperative blood pressure in both cats and dogs having routine neutering procedures.

The target was for patients to maintain a mean arterial blood pressure of 60mmHg during their anaesthetic.

The animals chosen for auditing were to be classed ASA 1 and under 5 years old.

They received a pre-operative health check including a blood pressure reading to ensure they were normotensive.

A first audit looked at a standard premedication protocol of ACP at a dose rate of 0.02mg/kg combined with methadone at a dose rate of 0.3mg/kg.

A second audit initiated a change to the pre-medication drugs, using 0.005mg/kg medetomidine combined with the same dose of methadone.

Both received anaesthesia induction with Propoflo at a dose rate of 6mg/kg for cats and 4mg/kg for dogs.

All patients under anaesthetic were maintained using isoflurane and kept at a surgical plane of anaesthesia appropriate for that patient.

The patients were monitored throughout their surgical procedure using an oscilliometric monitoring machine - for systolic, diastolic and mean arterial blood pressure – and measurements recorded on an anaesthetic chart.

The collected data revealed that in the first audit, where patients received ACP and methadone, 42% (50% of cats and 38% of dogs) had a mean arterial blood pressure lower than 60mmHg after the first five blood pressure readings post induction.

In the second audit, with medetomidine combined with methadone, only 11% of patients (0% of cats and 15% of dogs) with a mean arterial blood pressure lower than 60mmHg.

In addition to the reduction in hypotensive patients during anaesthesia when the medetomidine/methadone combo was used, Francesca says the audit suggests a link to hypotension with ACP used as a premedication in anaesthetised patients.

Francesca said: “My passion in veterinary nursing is anaesthesia. And there is always room for improvement and striving to achieve gold standard care.

“These results clearly show that a change from our current premedication protocol of ACP and Methodone to Medetomidine and Methadone decreased the number of patients having hypotension during anaesthesia. The change means fewer patients were at risk of developing the side effects associated with hypoperfusion of the vital organs.

“Our quality improvement initiative has made a really positive impact in practice for both patient care and clinical team.”

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