Types of Anaesthesia LOCAL ANAESTHESIA AND REGIONAL ANAESTHESIA PRPD/DN/2011.
avian anaesthesia bvna - Vet-ecpdCapnography:Whymonitor&CO2?...
Transcript of avian anaesthesia bvna - Vet-ecpdCapnography:Whymonitor&CO2?...
Birds are hard to keep alive...
•Advances in• Drugs• Monitoring• Understanding of birds
Anaesthesia provides…..
• Immobilisation•Analgesia•Muscle relaxation•Oxygen•Reduced stress?
Better control...
• Intubation• Ventilation
Isoflurane is safer than Adrenaline!
Before anaesthesia, consider…….
•Anatomy• URT• LRT
•Physiology• Air flow• Respiratory movements• Small Functional Residual Capacity• High Metabolic Rate
Patient Preparation
• Possible?• History and physical examination• Further examinations?• Pre-‐anaesthetic blood screens?• Acclimatisation• Fasting• Premedicants?
Really bad news....
Vet preparation
• Ready for the op?• Vet• Nurse• Assistants• Equipment
• MINIMISE THE TIME SPENT ANAESTHETISED!!!!
Induction
• Injectable vs gas?• Mask vs chamber• Restraint for mask• One-‐and-‐up or five-‐and-‐down?
Masks
Intubation: anatomy
Intubation: the tubes!
Problems associated with intubation
•Blockage• Tube smaller species?• Positioning?• Ventilate?
•Stricture• Species?• Type of tube?• Cleaning?• Length of tube & positioning?
Circuits
•Mask + elephant tube•Consider• Resistance• Dead space
•T-‐piece, Mini-‐lack, Bain, etc
What if we want to work on the head?
Air sac cannulation?
Maintenance
• Mask • Passive breathing• IPPV• Manual• Mechanical
• Volumetric• Pressure
Important Aspects
•Temperature!!!• Pads• Bottles, etc• Radiant
•Eyes•Blood loss•Position
You do need an anaesthetist
Their emphasis is on monitoring...
• Appreciate• Respiratory rate• Lung perfusion• Blood oxygenation• Heart rate/ regularity• Pulse rate/ regularity• Peripheral blood flow• Body temperature
Effect of Ventilation...
Haven’t mentioned reflexes...
Capnography: Why monitor CO2 ?
•Carbon Dioxide production is constant and its expired level reflects both cardiovascular and respiratory efficiency•All the Capnograph profiles and End-‐Tidal values you will see can be explained by remembering the above statement• It is an early warning system for hypoxia•Simply put it tells you that the animal IS breathing and how well it is breathing
What information do we get from Capnography?• Capnography gives us continuous information on Expired and Inspired CO2 concentrations• Expired CO2 (PetCO2) is a reflection of the PaCO2. • There will always be a gradient between PetCO2 and PaCO2 but other than in extreme circumstances, this is usually only 1-‐4 mmHg• In addition to the End-‐Tidal value the Capnogram shows the levels of CO2 during the complete respiratory cycle• The Capnogram waveforms provide a lot of information
Typical Capnogram
• Phase 0 – Inspiration. Rapid fall in CO2 levels as new breath taken• Phase I – Beginning of expiration and the elimination of gas from anatomical dead space• Phase II – Alveolar gas mixes with dead space• Phase III – Main component of expiration. Has a typical positive slope
Peripheral Blood Flow
• Consider• Pulse rate• Rhythm• Strength
ECG
Reduce wires?
What about the good old pulse ox?
But if you want a sensitive, reliable, reactive anaesthetic monitoring device...
Is there a place for injectables?
• Field anaesthesia?• Or iso + air??
• Special species• Ratites
• Total injectable regimes?• Sedation only?
Analgesia
• Do birds feel pain and how to assess?• NSAIDs• Opiates• Local anaesthesia• Dissociative agents
Consider analgesia if…..
• Would the lesion be painful to a human?• Is the lesion damaging to tissues?• Does the bird display behaviours that may indicate pain?• Change in temperament, restlessness, reduced grooming, reluctance to perch, lethargy, reduced appetite, constipation, dyspnoea, lameness, biting/ chewing at wound, tonic immobility
Emergencies
• Respiratory vs cardiac depression• Protocol as in mammals
ABC…
•A•B•C•D•F
irwayreathingirculationrugsluids
Recovery
• Supervise till standing• Extubation• Wrap
In summary...
• Birds are commonly anaesthetised and can be quite stable!• Anaesthesia is usually reactive, not planned• There is no easy GA!