What is the importance of monitoring temperature in recovery from anaesthesia?
- Normothermia required to maintain perfusion of tissues
- Low temperature means low metabolism and so extended half life of drugs used
How can temperature be maintained in recovery from anaesthesia?
- Warming and humidifying of air (circle system better)
- Bubble warp/socks/space blankets
- Hot water beds
- Warming of IV fluids and flushing solutions
- Hot air blankets on dry patients
Describe the use of analgesia in recovery from anaesthesia
- Need to ensure comfort of patient
- Vocalisation/restlessness may be due to: pain, dysphoria, emerging from anaesthesia, discomfort (e.g. need to urinate)
- If in doubt, give analgesia and reassess
Give examples of anaesthetic complications in the horse that may only manifest in recovery
- Hypotension
- Hypxamia
- Hypercapnia
- Poor positioning
- Post-operative myopathy
- Post-operative neuropathy
- Spinal cord malacia
- Eye problems
- Nasal oedema
- Laryngeal obstruction
- Pulmonary oedema
- Colic
How does hypotension occur in the horse during anaesthesia?
Lots of drugs administered that will reduce blood pressure
How does hypoxamia occur in the horse during anaesthesia?
Occurs with lung collapse, less lung tissue is ventilated and perfused, rest of lung has significant v/Q mismatch
Outline how poor positioning of horses during anaesthesia leads to complications
- Horses unable to ventilate properly when in dorsal recumbency
- In lateral, need to ensure limbs are parallel otherwise one will be under pressure and lead to compression of nerves or muscle
Outline the cause and presentation post-operative myopathy in horses
- Occurs when horse wakes up
- Caused by intra-operative malposition and hypotension
- Ranges from mild lameness to complete inability to stand
- Hard, swollen, painful muscles
- Extreme distress, sweating, difficulty breathing, restlessness
Describe the treatment of post-operative myopathy in horses
- Administer ACP
- Place in sling to take weight off legs
- Administer fluids (myoglobin release from muscles which will damage kidneys)
- Increase perfusion of muscles
- Analgesia
Describe post-operative neuropathy in horses
- Seen when horse wakes up
- Caused by pressure on nerve and hypotension
- Commonly facial nerves or nerves supplying limbs
- Return to normal is possible, if mild can return over 7 days
Describe spinal cord malacia in horses
- Fatal, no chance of recovery
- Commonly heavy breed and young horses
- Not related to duration of anaesthesia
- Caused by disruption in blood flow to spinal cord
- Horse sits like a dog, areflexic in hind limbs
Describe eye problems see in horses anaesthetic complications
- Usually when horse has been in lateral recumbency
- Must protect lower eye with padding
- Lubrication for the eyes needed, iso, ket and sevo decrease lacrimation
Describe upper airway obstruction in horses post-operatively
- Usually within nasal passages or at level of larynx
- Stridor or stertor following tracheal extubation
- Nostril flaring on inspiration
- Abdominal respiratory effort
- Exaggerated thoracic excursion
- Absence of airflow at the nostrils
What is stridor?
Wheezing sound on respiration
What is stertor?
Heavy snoring or gasping sound on respiration
Describe nasal oedema in horses post-operatively
- Common, usually resolves as horse stands
- Caused by disruption of venous outflow of head
- Use nasopharyngeal tube, or phenylephrine or both
- Can recover horses with ET tube in place
Describe laryngeal obstruction in horses post-operatively
- Caused by dorsal displacement of soft palate and epiglottic retroversion
- Avoid by selecting appropriate ET tube size and inserting gently
- Leave ET tube in place for recovery after laryngeal surgery
- May require emergency tracheostomy
Describe pulmonary oedema in horses post-operatively
- Frothy, pink fluid at nostrils after horse has been re-intubated and airway patency returned
- Exaggerated respiratory effort and cyanosis
- Thought to be related to changes in venous return and influx of fluid into the alveoli as a result of excessive negative pressures within thorax
- Remove obstruction, provide oxygen, frusemide and dexamethosone
Why might colic occur as a post-operative complication in horses/
Loss of of reduced perfusion to the GIT during surgery
What methods of monitoring and support can be used to prevent post-operative complications in horses?
- Pulse oximeter
- Viewing using CCTV, over top of box door etc
- Ropes to aid standing
- Sitting on neck to slow standing until fully ready
- Sedation and analgesia
- Placing urinary catheter so horse does not have full bladder and wanting to stand too soon (can only urinate standing)
