Equine Anaesthesia & analgesia COPY Flashcards
What drugs used in staning sedation?
How do we ‘top up’ duration of sedation?
- ‘Top up IV
Alpha 2 agonist infusion (detomidine, xylazine or romifidine)
AEs of Sedation? - Alpha 2 effects
- Sweating
- Ataxia
- Sinus bradycardia, 1st & 2nd degree AVB, respiratory depression
- Increased urination
- Ileus, oesophageal choke (Starve for a couple of hours after sedation)
- Gas distension, colic (repeated administration)
- Tachypnoea in febrile horses.
- Localised inflammatory response if drug accidently injected s/c or
peri-vascular - Horses can appear profoundly sedated but still startle and react with
well-directed kicks - Individual/breed differences in susceptibility – eg draft breeds very
sensitive to sedation
AEs of sedation with opioids?
- Ileus, Impaction colic
- Horse can startle
Describe sedation of foals under 2 weeks old ?
- Cardiac output directly related to heart rate: hypotension occurs quickly
- Avoid alpha-2 agonists due to cardiovascular effects
- Benzodiazepines and opioid combination readily causes recumbency
Multimodal analgesia - waht NSAIDS for equine?
Phenylbutazone, suxibutazone, fluxinin, melocixam, firocoxib, carprofen
What opioids in multimodal A?
Butorphanol, Morphine, Buprenorphine, Pethidine, Methadone
What locals can we. use?
Lidocaine, mepivicaine or bupivicaine
What adjunct analgesia ?
-> Infusions (of individual drugs or combinations)
-> Alpha 2
-> Paracetamol
-> Gabapentin
What does CEPEF stand for?
Confidential Inquiry into Perioperative Equine fatalities
What did SEPEF find was mortality within 7 d of procedure?
- All Patients: 1% (Prev 1.9%)
- ‘Noncolic’ patients: 0.6% (Prev 0.9%)
- ‘Colic’ patients: 3.4% (Prev 7.8%)
- Standing sedation 0.2%
- Causes: Fracture in recovery, post-operative colic, others
- Highest numbers of deaths during recovery
What factors increase the risk of Death ?
Total inhalant anaesthesia
Duration >2 hours
Increasing adult age
Out of hours anaesthesia
Midnight to 6am x 7.61
6pm to midnight x 2.15
Weekend x 1.52
Higher ASA physical status grade
Lack of premedication
What decreases risk of mortality?
Total intravenous anaesthesia (TIVA)
Duration <2 hours
Acepromazine premedication
What are some common Anaesthesia- associated complications?
- Fractures, joint dislocation
- Post-op colic, Post-anaesthetic ileus
- Cardiac arrest, cardiac arrhythmia
- Upper airway obstruction, Nasal Oedema, laryngeal paralysis
- Endotracheal tube complications
- Pulmonary oedema
- Post anaesthetic myopathy
- Neuropathy
- Spinal cord myelopathy or cerebral necrosis
- Hypoxaemia
- Hypotension
What complication from arterial and venous cannulation?
Venous thrombophlebitis
Inadvertant placement of venous cannula into caroti Artery
Exsanguination and air embolism
Accidental breaking, cutting of canula or loss of guidewire
What contributing factors to anaesthetic -associated complications?
- PAtient positioning
- Anaesthetic drugs
- Mechanical ventilation
- Pre-existing dx
- Human error
What common fractures during recovery?
Tibia, carpus, radius most common
Who gets more fractures?
Older TB mares over-represented - reduced bone density in PP mares?
What can they get as result of fractures during recovery?
- Reduced limb strength after repair
- Fatigue in severely ill horses
- Fracture of contralateral limb after fracture repair
- Also join luxations/ dislocations
What is the most common cause of peri-anaesthetic death?
Cardiac arrest
Risk factors to upper airwar obstruction?
- PRe existing left laryngeal hemiplegia
- Large body mass
- Prolonged anaesthesia
- Hypoxaemia
Signs of UAO?
- resp distress
- Blood stained foam pouring from nostrils and mouth
- Deterioration with hypoxemia, collapse and cardiac arrest may be rapid
Tx for UAO?
Establish an airway (ET tube or tracheotomy followed by symptomati tx (oxygen, furosemide, bronchodilation)
What has bilat laryngeal paralysis been associated with?
- Nerve damage due to neck extension
- LAryngeal nerve ischaemia
- Tissue oedema due to surgery
- LAryngeal oedema and spasm
- Functional airway collapse
Why can we get nasal oedema?
- with dorsal recumbency
- can lead to upper airway obstruction
Prevention of nasal oedema?
- Use lateral recumbency
- Orotracheal tube in situ or naso-pharyngeal tube placed for recovery to bride gap until nasal passages return to normal function
- Intra-nasal phenylephrine into ventral meatus at end of anaesthesia to reduce congestion and obstruction
What ET intubation complications can they get?
- Mild-moderate mucosal damage is common
- Haemhorrhage with potential for airway obstruction by
blood clots, aspiration - Laryngeal oedema, ecchymosis and haematomas, paresis
- Bilateral larnygneal paralysis (rare)
- Pharnygeal trauma
- Tracheal damage from cuff
- Secondary bacterial infection, pleuropneumonia
What can cause pulmonary oedema?
- UAO
- Micro-embolism
- Drug-associated capillary leakage
- Venous air embolism
- Mechanical causes (hydrostaticeffects)
what does PAM stand for?
Post Anaesthetic Myopathy and Neuropathy
What is PAM associated with?
- Dec muscle perfusion related to hypotension (MAP < 65mmHg)
- Prolonged duration of GA
- LAteral recumbency
- Larger body mass