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Maintenance with Alfaxan

Following induction anaesthesia may be maintain with an inhalation agent or for the dog and cat with intravenous Alfaxan 44, 53, 54

Inhalational Maintenance

Transition to inhalational maintenance

Should only occur only once endotracheal intubation completed and the patient has stable alveolar ventilation (i.e. no apnoea).

Successful maintenance relies on a number of factors including the choice of volatile agent, the breathing system used and the flow rate.

Monitoring

Good monitoring is a combination of traditional (relying on ones senses) and modern monitoring equipment. Multi-parameter monitoring is the ideal but never rely upon equipment alone.

Key considerations for monitoring include: Anaesthetic depth, ventilation, the cardiovascular system and body temperature. 44, 53, 54

Record Keeping

It is important to keep good records of any anaesthetic and specifically designed monitoring charts are ideal for this.

Look out for trends during the anaesthetic as these are more important than one off values. The charts make for easier hand overs and post op planning and allow the whole team to see when other medications were administered and at which dose.

Request our monitoring chart

Essential Equipment

Obviously your senses – sight, touch, hearing and smell are essential and you will need a thermometer, a pen and a stethoscope (ideally and oesophageal one).

The Cardiorespiratory System During the Maintenance Phase

It is important to continuously monitor the heart rate and rhythms well as other parameters linked to the CR system:

  • Does the patient have an appropriate HR for its age, species and type of premed administered (e.g. α2 agonist)?
  • What is the pulse rate and quality? Peripheral pulse is preferred to femoral as it gives a better indication of blood pressure.
  • Is the pulse synchronised with the heart beat?
  • Are the mucous membranes a healthy colour with an appropriate capillary refill time?
  • What is the hydration status? Has blood loss occurred? Is hypovolaemia expected?
  • What is the respiratory rate and effort? Is there any apnoea? Does the patient require ventilation? Check the ET tube is not occluded.


Temperature

The ideal range for an animal under anaesthesia is between 36.5°C and 38.5°C for the dog and cat – this should be checked continuously via a probe or every 30 minutes as a minimum. It is important to maintain temperature body temperature to prevent delayed recoveries.
Many drugs given during premedication can affect the thermoregulatory centre and/or cause peripheral vasodilation, as can induction and volatile agents.

Other risk areas include if the patient is in a cold kennel, is wet and / or stationary and following surgery which has required open body cavities.

Capnography

Important part of the monitoring process which measures:

  • Cellular metabolism
  • Circulation
  • Respiration
  • Gaseous exchange
  • Equipment issues
  • Some possible complications
    • ET tube obstruction
    • Exhausted soda lime
    • Impending cardiac arrest

Blood Pressure

Maintenance of blood pressure ensures adequate renal perfusion and therefore aids homeostasis

Mean Arterial BP gives information on the overall driving blood pressure and tissue perfusion. In cats and dogs maintain MAP at >60mmHg minimum, ideally >80mmHg. In the rabbit maintain Systolic AP 92-135mmHg ensuring the correct cuff size is used. See BSAVA Manual of Rabbit Medicine 2014.

Vasodilation results in hypotension and many of the drugs associated with anaesthesia will cause vasodilation.

Pulse Oximetry

Measures oxygen saturation of haemoglobin. The sensor is placed on depigmented extremities with a pulsatile capillary bed (e.g. tongue, digits) and the pulse rate is displayed

Aim for oxygen saturation levels of above 90% (Ideally >95%)

Electrocardiogram

Checks for arrhythmias but should not be used alone.

Other

Check airway pressure gauge on ventilators are set appropriately to avoid barotrauma

Puppies and kittens are prone to hypoglycaemia. Ensure regular checks of blood glucose are performed and suitable treatment is available should it be required

Alfaxan Maintenance Dosage

Cat Maintenance Dose

Un-Premedicated Premedicated
Dose for constant rate infusion
10 - 11 mg/kg/hour 7 - 8 mg/kg/hour
0.16 - 0.18 mg/kg/min 0.11 - 0.13 mg/kg/min
0.016 - 0.018 >mL/kg/min 0.011 - 0.013 mL/kg/min
Bolus dose for each 10 minutes maintenance
1.6 - 1.8 mg/kg 1.1 - 1.3 mg/kg
0.16 - 0.18 mL/kg 0.11 - 0.13 mL/kg

Dog Maintenance Dose

Un-Premedicated Premedicated
Dose for constant rate infusion
8 - 9 mg/kg/hour 6 - 7 mg/kg/hour
0.13 - 0.15 mg/kg/min 0.10 - 0.12 mg/kg/min
0.013 - 0.015 >mL/kg/min 0.010 - 0.012 mL/kg/min
Bolus dose for each 10 minutes maintenance
1.3 - 1.5 mg/kg 1.0 - 1.2 mg/kg
0.13 - 0.15 mL/kg 0.10 - 0.12 mL/kg
Repeatable. Reliable. Relax.