VNJ Volume 40 (3) June 2025 | Page 44

Once surgery was completed, preparations were made for a smooth recovery. A decongestant nasal spray( Otrivine, Haleon) was applied in the nares to open the nasal passages. Nebulisation was also performed via the endotracheal tube with 2 ml of 1:1000( 1 mg / ml) adrenaline and 3 ml 0.9 % saline. A sedation plan was created whereby 3 μg / kg medetomidine was made readily available in case of overt distress or dysphoria on recovery. Once the patient was extubated and his oxygen saturation was consistently around 98 % on pulse oximetry while breathing room air, he was transferred to the ward.

Discussion

Premedication

The patient received IM sedation as premedication. The IM route of administration can be useful when IV access is difficult, such as in aggressive, anxious or highly excitable patients. It can also be less stressful as it requires less restraint of the patient and the drugs used can provide anxiolytic effects. This is especially important in brachycephalic breeds, where reducing stress can minimise the risk of airway obstruction.

The patient ' s premedication comprised 0.2 mg / kg methadone and 15 μg / kg medetomidine. Methadone is a full mu receptor agonist and therefore provides extremely efficacious analgesia. Medetomidine is an alpha-2 adrenoceptor agonist that provides analgesia via a different neural pathway from that acted on by methadone, and has additional sedative effects. The combination of these drugs results in a synergism that increases their individual potencies [ 3 ].

Use of medetomidine is not always clinically appropriate as stimulation of the alpha-2 adrenergic receptors can result in significant bradycardia, meaning that the use of this drug( especially at the dose required for this patient) may not be appropriate for patients with cardiac disease such as mitral valve disease [ 4, 5 ].

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Overall, IM premedication of this patient successfully permitted IV catheter placement and the smooth induction of anaesthesia.

Anaesthetic considerations during MRI

Sufficient premedication can reduce the dose of anaesthetic induction agent required [ 4 – 6 ]. This was demonstrated in this case, where minimal propofol( 35 mg) was required to induce anaesthesia. This approach can reduce the side effects of such agents, which include apnoea and hypotension. Following intubation of the patient, a semiclosed circle rebreathing system was attached. This provided a 50:50 mix of oxygen and air, as well as the maintenance inhalant agent isoflurane.

MRI is a radiological imaging technique that produces threedimensional detailed anatomical images, which are created by radio waves that interact with hydrogen atoms in the body [ 7, 8 ]. Images can be disrupted by the presence of metallic objects, and the machine can also become damaged by the presence of any such objects. Clients are therefore required to complete an MRI patient safety questionnaire to screen for any metallic implants other than a microchip.

A safety checklist is also performed by staff before entering the MRI room, to ensure no metal is present. While the MRI is in progress, staff are advised to remain outside the room to minimise their exposure to the loud sounds produced by the machine, and ear buds are placed in the patient ' s ears to protect against this noise. Remote monitoring of the patient is therefore required throughout the MRI, and there is minimal opportunity to perform physical assessments of anaesthetic depth.

The patient is placed in dorsal recumbency when scanning the spinal region [ 9 ], which may be painful for the patient. Patients placed in dorsal recumbency may

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