Ch.22 Complications of Inhalation Anesthesia and their Management Flashcards
How does hypothermia affect oxygenation
Shifts the oxygen haemoglobin dissociation curve to the left reducing the oxygen available to the tissues
How does hypothermia affect drug dosage and clearance
MAC reduced 5-8% per 1*C drop in temp
Lower rate of clearance
At what HR is action taken when horse under GA
18-20
When is anticholinergic use advised
If bradycardia is accompanied by hypotension despite inotropic and fluid support
or
the arrhythmia is significant enough to cause fear of asystole
Anticholenergics used to correct bradycardia
Atropine - slows GI most - Colic complication
Hyoscine-n-butylbromide
Glycopyrolate - used with xylazine - least effect on GI
What must be discontinued before using anticholinergics
Sympathomimentic drugs like dobutamine, ephedrine, dopamine as can cause serious dysrhythmia
What other drugs can be used to address bradycardia
Sympathomimmetics but will need a larger dose than for hypotension
Addressing bradyarrythmia caused by hyperkalemia such as bladder rupture, UT obstruction, HYPP
IV Calcium, Sodium bicarbonate,
additional use of glucose, insulin, furosemide if not correcting
What horses experience tacchyarrythmia under GA
Compromised horses who have not been stabilised with fluids prior to SX
What dose of lidocaine can be used to address ventricular tachycardia
0.5-1mg/kg
How do inhalant anaesthetics affect myocardial contractility
Dose dependent reduction
Vasodilation in compromised horses
What is the target mean arterial blood pressure
70-90mmHg
What does Dobutamine act on and what dose should it be administered
0.5 - 2ug/kg/min
Inotropic drug - mostly Beta 1 receptors
Beta 1 adrenergic agonist
What should be used if hypotension is being caused by vasodilation such as in endotoxemia
Drugs with mixed alpha and beta effects eg ephedrine 0.05 - 0.1 mg/kg/iv
or
alpha only eg phenylephrine 1 - 2 ug/kg/iv
Mean arterial pressure for foals
50-65mmHg
