avian anaesthesia bvna - Vet-ecpdCapnography:Whymonitor&CO2?...

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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!