FGF and ASA risk scores

How is FGF calculated for non-rebreathing circuits

TV X RR = MV (minute volume) 

MV x Circuit factor = FGF 
 

What are the normal tidal volumes

• 15ml/kg for cats and small dogs 

• 12ml/kg for medium dogs 

• 10ml/kg for large dogs 

How do you calculate FGF for rebreathing systems

• Induction rate- 100ml/kg/min for 5-10 mins 

• Maintenance rate- 10ml/kg/min (0.5-1L is sufficient for those under 50kg

• A maintenance rate of <0.5l/min may cause vaporiser inaccuracy 

What factors affect the metabolic rate for FGF

• Temperature

• Age

• Fitness

Why do we calculate FGF

• We calculate FGF to purge the system of air and fill it with fresh gas

• Also provides sufficient anaesthetic agent for rapid stabilisation of anaesthesia depth 

 

What do we need to do to complete a pre-anaesthetic assessment and prep

• Patient assessment

• Patient preparation

• Equipment preparations

• Preparing

What comes under a patient assessment

• Temperament

• Cardiac

• Respiratory

• Temperature

• Hydration

• Neurological status

• Pain

• Clinical history

How can we reduce stress and anxiety prior to GA

• Pheremones e.g. flyway and adaptive

• Sedatives e.g. gabapentin and trazodone

• Oromucosal e.g. dexmedetomidine gel

When should we do PABS

When is an echo indicated

When should we fast patients before GAs

How can we reduce regurgitation + / - aspiration

Omeprazole 

• In dogs 1mg/kg oral omeprazole given twice in 24hrs before anaesthesia significantly reduces acidity of gastric pH 

Maropitant 

• Reduction of opiate and alpha-2 adrenergic agonist reduces nausea and vomiting, total opiate and inhalational requirements and visceral nociception 

• Smoother recovery transitions and faster return to eating post-op  

What equipment do we need to prep

• Oxygen 

• Flowmeter 

• Vaporiser 

• Scavenging 

• Paperwork 

How do we check breathing systems

• Visually inspect and leak test 

• Close APL valve for leak test and reopen fully 

• Check soda lime for exhaustion 

• Check inside tubing of coaxial system for leaks 

• Open APL valve when done 

What do we need to take into account when ASA grading

• Species-are you familiar with the anatomy, physiology, disease, pathology and pharmacology 

• Equipment- are you familiar with the equipment you are using 

• Breed (if relevant)- does the breed you are anaesthetising have an increased ris

What is grade 1 ASA score

• Normal healthy animal

• No detectable underlying disease

What is grade 2 ASA score

• Slight to mild systemic disease

• Causing no obvious clinical signs or incapacity

• Neonates

• Geriatric

• Obese

What is grade 3 ASA score

• Mild to moderate systemic disease

• Causes clinical signs

What is ASA grade 4

• Extreme systemic disease

• Constitutes a threat to life

What is ASA grade 5

• Moribund and not expected to survive for more than 24 hours without surgery

What considerations need to be made when choosing drugs

• Patient

  • Temperament

  • ASA grade

  • Age

  • Breed

• Procedure/surgery

  • Aim

  • Analgesia required?

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What do owners need informed consent about

• Cost

• Procedure breakdown

• Risks

• Benefits of procedure

What should be part of the checklist

• Pre-induction

  • Check patient

  • Check equipment

  • Check staffing

• Pre-procedure

  • Communicate safety concerns

• Recovery

  • Check all procedures are done prior to recovery 

  • Analgesia plan 

  • Ongoing monitoring-hand over to ward team to monitor/anaesthetic nurse 

What are the main considerations for positioning

• Well padded  

• Neutral position  

• Avoid overextension and/or flexion  

• Consider pain e.g. OA  

• Avoid eye trauma  

• Avoid damage to trachea/ETT obstruction – e.g. breathing system pulling on ET tube 

What are the considerations for dorsal recumbency

• Diaphragm pressure-worsened by abdominal distension (all organs come up and push on diaphragm) 

• Hypoventilation 

• CV effects- reduced venous return and cardiac output (worse in large breeds) 

What are some general positioning considerations

• Avoid excess movement/position changes- increased risk of regurgitation/aspiration 

• Avoid limbs hanging over the edge of a table or use suitable padding- avoid compartment syndrome 

• Ensure heat sources are not too hot and are well protected to prevent burns 

• Disconnect the anaesthetic circuit from the ET tube when repositioning—prevents tracheal damage 

• Give time in sternal when turning from one lateral recumbency to another due to atelectasis (collapsed lungs) 

• Anal/perineal surgeries may require a head down angle (trendelenberg position)- causes hypoventilation