Exotics 3: Anaesthesia of exotic species Flashcards
LOs
- Confidently approaching an exotic patient for anesthesia:
o Performing pre-anesthetic checks and patient risk assessment;
o Selecting appropriate drugs for each patient;
o Monitoring anesthesia across species;
o Recovering patients from anesthesia; - Recognizing potential complications before, during and after anesthesia;
- Performing emergency resuscitation in exotic patients.
What is ASA status?
classification system categorising patient’s physiological status that can help predict operative risk
What are considerations we need to make when GA exotic animal?
- High incidence of chronic and subclinical disease
- Susceptible to heat loss and hypothermia
Exceptions: penguins and other marine birds prone to hyperthermia! - Most species not domesticated = peri-anaesthetic stress – handling
- Smaller species: (most less than 1kg)
= Difficult venous access
= Limited anaesthesia monitoring - > morbidity/mortality vs smallies
What do you have to think about wrt exotics and nostrils in GA?
o Present in most species
o Tubular extensions – petrels
o Absent – cormorants, pelicans, gannets = breath through beak so don’t restrain by beak as can suffocate
* Complex Nasal cavities connecting to infraorbital sinuses which are connected to cervico- cephalic air sacs
What do you have to think about wrt exotics and Glottis in GA?
o SIMPLE, Easily visible (except flamingos) and accessible
o Glottis Diameter > trachea so careful with selection ET tube (hole in pic)
What type of ET tube do you use in birds? and why?
- Complete, partially overlapping rings – ALWAYS use uncuffed ETTs
o If use cuff, NEVER inflate as can cause severe trauma
o Unable to accommodate something increasing in size in lumen - Proximal narrowing of lumen, be careful with ETT advancement
o Slightly smaller than what expect to use - Some species have Long, complex trachea shapes (cranes, some swans and fowl) – lot of dead space
- Bifurcated trachea in some species, almost next to glottis = use adapted ET tube – penguins
What is the Syrinx?
- Where trachea bifurcates we have the syrinx = vocal organ
- Bifurcation of major bronchi
o Vocalizations during insp/exp - Can build up Tracheal mucus:
o Can cause partial/complete ETT obstruction (pigeons and ducks ++)
o Monitor oximetry and ventilation
Bird Diaphragm
ventilation relies mostly on rib movements
* Reduced ventilation on dorsal recumbency (weight of pectoral muscles)
* Complex air sac system
o Communicate with pneumatic bones
o Compressed by effusions, enlarged organs or fat deposits
What is the blood gas exchange like in the bird
o Extensive area for gas exchange – air sace
o Communicate with lungs and pectoral bones (humerus and femur)
o Anything fluid, mass, restraint = compresses ventilation
o Efficient blood gas exchange extensive areas
o Counter-current mechanism
o Occur during inspiration AND expiration
o Birds have higher O2 demands = Hypoxia is very possible
- Counter current movement. Air flow and blood opposite wasyyv= inc transfer efficiency gas exchange.
BIRD CV system
- Higher HR for body mass
- Higher BP (normal = 90-180mmHg):
o Increased risk of atrial/arterial rupture? (capture/restrain)
Shouldn’t happen during anaesthesia but restraint - Higher tolerance to blodo loss, haemorrhage and anaemia
o RBCs with shorter half life
o So replaced a lot more frequently - Renal Portal system – does it affect drug administration?
Do we fast birds?
o Not advised to smaller species (<500g) or debilitated patients
o 2-4h for larger species (>500g)
o ALWAYS Confirm crop is empty –
o Risk regurg when induce anaesthesia, esp birds of prey, piscivorous birds or fledglings
* If possible, correct any abnormality prior to anesthesia: DELAY
o Supplemental fluids + glucose
o Supplemental feeding
o Medication depending on case
* Plan ahead for minimal time under anaesthesia
* !!!!Eye lubricant – globe doesn’t rotate during GA !!!!
o Can have server corneal damage
What do you need to remember about African grey parrots?
o V prone to hypocalcemia = give Calcium pre-anaesthesia
o Check ionized calcium (+/- Mg) pre-anesthesia
o Routinely supplement with Calcium pre-anesthesia?
What are indications for sedation? in birds
o Clinical exam stressed, prone to trauma patients
o Short procedures (blood sampling, x-rays, beak trim, etc.)
o Pre-medication for anaesthesia
What is the importance of sedation in birds?
o Reduces stress of handling
o Reduces of anesthetic gas
o Amnesic effect (midazolam)?
What sedation would you use for birds?
- Midazolam 0.5mg-2/kg + Butorphanol 0.5mg/kg IM, IN (Intra nasally)
o combination - Reverse w/ Flumazenil 0.03-0.05mg/kg (= volume Midazolam)
o Reverses midazolam
+oral Ca for African grass
