Question | Answer |
What are the three most common problems with equine anaesthesia? | hypoventilation, hypoxia and hypotension |
what may cause a horse to hypoventilate on anaesthesia? | sedative, IV and volatile anaesthetics, opioids, muscle relaxants and positioning. |
how can the horses CO2 be assessed? | Arterial blood gas analysis and capnography |
what does sever hyper capneia cause? | acidosis, narcosis, increased risk of arrthymias and hypoxaemia |
why is mild hyper capnea benifitial? | myocardial contractility and improves tissue blood flow |
what is good hyper capnea? | upto 70mmhg |
How should hyper capneia be treated? | IPPV and reducing anaesthetic depth. IPPV should be done at 6-8 bpm and 20-30cmH2O pressure. |
Why is IPPV dangerous in hoses? | it increases the anesthetic and cardiovascular effects, it can disturb the blood base balance and damage alveoli |
What are the two ways to measure hypoxia in a horse and how do they differ? | PaO2 and spO2. PaO2 is the partial pressure of O2 in the blood whilst spO2 is the saturation of the haemoglobin. |
How is spO2 and PaO2 measured? | spO2 is measured by pulse oximeter whilst PaO2 is done by arterial blood gas analysis. |
what are the values where they are considered hypoxic? | 90% spO2 and 60mmHg PaO2 |
what are the causes of hypoxia? | VQ mismatch, hypoventilation, low inspired O2, shunts and diffusion abnormalities |
what are the two most likely causes o hypopoxia in a horse during anaestetic? | VQ mismach and hypoventilaion |
Why arent the whole of the lungs per-fused during anesthetic? | gravity, low contractility/ spO2 and PaO2 heart rate and vasodilation. The body would usually respond by undergoing hypoxic pulmonary vasoconstriction, although this is stopped by inhalants. |
how should VQ miss-mach be treated? | IPPV, positioning, NO2 administration which acts as an alveolar splint, air and O2 mix so it isn’t absorbed. IPPV deals with the oxygenation, to deal with the perfusion drugs are required, Beta agonists (salbutamol) by inhalation (often doesn’t work)is the choice. |
what is PEEP | IPPV method which also known as the recruitment manoeuvre or open lung concept. It works by ventilating the lungs to 60-80cmH2O and leaving it there for 12 seconds done 8 times, followed by 10 PEEP at 20cmH2O. |
what does hypoxia cause? | myopathies, cause problems in the CCN and cause spinal cord malacia, and myocardial or cerebral disfunction. |
what is hypotension? | low blood pressure its when the mean atrial pressure is <60-70mmHg |
How is man atrial pressure calculated? | Hr X SV X TPR |
what are e side effects of anticholinergics? | pupillary dilation, GI ileus and tachycardia. |
when should anticholinegics be used in an anesthetic? | ABP <60 and the HR is <20-25bpm |
what are the two anticholenergics available for use? | Glycopyrrolate and atropine |
what is stroke volume directly effaced by? | preload, contractility and afterload |
what causes a reduction in pre load? | dehydration, haemorrhage, positioning (supine hypotension) and with IPPV (pushes on VC). |
what decreases contractility? | arthymias, volatile agents and acidaemia |
what causes a decrease to the after load? | vasoconstriction, increased resistance from the heart and weak cardia compressions. |
what drugs increase the after load? | adrenalin, alpha agonists, dopamine and phenylephrine. |
what is the worry if after load is increased too much? | The CO will decrease |
how should hypotnsion be treated? | checking the depth, providing IVFT (crystalloids, colloids) and possible use of the following drugs; inotropes (dobutamine, ephedrine and dopamine) and vasopressors (phenylepenephrine). |
what factors may make the horses recovery more dangerous? | long procedures, True emergencies include: long procedures, the type of anesthetic, poor recovery box, full bladder, noise, pain, temperament and pre existing problems such as laminitis |
what are the desired factors of an equine recovery room? | quiet, has controlled lighting, padded, no corners, cleanable, wide doors, an observation spot, o2 supplimentation, close to the operation room, has a scavenging system, winches and escape route for staff. |
What may be complications of recovery? | myopathy, neuropathy (peripheral and central), airway obstructions, trauma (orphorpaedic and soft tissue) colic and catheter problems. |
how man anesthetic deaths is myopathy responsible for? | 7% |
how does compartmental syndrome occur? | tissue has more pressure than the bloods hydrostatic pressure, therefore blood vessels get occluded, and the muscle starts to die off. |
what are the signs of myopathy? | swollen, painful, hot, reduced function, myoglobinuria. |
what horses are at risk of myopathies? | fit racehorses, heavy horses, hypotension, hypoxaemia, repeated anesthetic and on their backs. The treatment of po |
how are post anesthetic myopathies teated? | nursing care, support (i.e. slings), analgesia (combinations of opioids, NSAIDs and alpha 2’s), fluid therapy, sedation and free radical scavenging. |
How are peripheral neuropathies caused? | compression or stretching of nerve fibers, often from poor positioning. |
How should peripheral neuropathies be treated? | Support the animal they often recover by themselves |
what central neuropathies may occur in the horse post anaesthetic? | spinal cord malacia, cerebrocortical necrosis and blindness |
what are the re disposing factors to central myopathies in the horse post anesthetic? | rapidly growing and dorsal recumbency |
what factors may increase the likely hood of nasal oedema? | positioning of the head (dorsal recumbency), fluid therapy and duration of anesthesia. |
how may the horses larynx be damaged on anesthetic? | stretching/ischaemia if the intubation was traumatic or too big, or if the animal had preexisting laryngeal hemiplegia. |
How should laryngeal problems be treated in the horse? | wait and see, if they go down re intubate, cpcr and frusemide and steroids for the pulmonary oedema. |
what can be done to increase he chances of a smooth recovery? | sedative, ACP would be the first choice, the animal needs adequate analgesia, empty the bladders, pack the ears, dim lighting, make sure quiet, cover the eye and maintain an airway. |
how long should recovery take in a hose? | Its extremely variable but suggested 30 mins for every hour. |
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