Anesthesia complications Flashcards
Normal arterial blood pressure is approximately
120/80 mmHg
normal mean arterial pressure is between
70-90 mmHg
The minimum acceptable mean arterial pressure for anesthetized small animals is
65 mmHg
name the 3 main anesthetics that cause hypotension:
vapors
propofol
acepromazine
Most anaesthetic drugs produce cardiovascular depression, which tends to decrease blood pressure.
the most common cause for low blood pressure in surgical patients is
Isoflurane (can induce profound hypotension)
Acepromazine and propofol both cause
vasodilation and thus hypotension
3 drugs of choice for the treatment of hypotension:
dopamine
dobutamine
noradrenaline
(glycopyrronium bromide)
Acepromazine, inhalants, and induction agents such as propofol and alfaxalone decrease temperature because
of
vasodilation and/or as a result of slowing metabolism.
what temp is defined as hypothermia?
anything lower than 38’C
passive rewarming is not useful if
the animal is already cold
(if its cold on the inside, it cant heat itself up. you need an active warming source)
Arrhythmias broad causes (2)
cardiogenic and non-cardiogenic
The majority are non-cardiogenic causes (pain, blood loss, hypoxemia, hypercapnia, hypothermia, electrolyte imbalance etc.)
Arrhythmias are divided into what groups based on rhythm
Bradyarrhythmias
¡ Sinus bradycardia
¡ Blocks (Sinoatrial block, Atrioventricular block)
Tachyarrhythmias
¡ Sinus tachycardia
Ventricular arrhythmias
¡ Extrasystoles
Bradycardia in large dogs
<50 bpm
Bradycardia in small dogs
<70 bpm
Bradycardia in cats
<100 bpm
Bradycardias are generally a result of: (4)
- administration of vagotonic drugs (α-2 adrenergic agonists, opioids)
- stimulation of vagally mediated reflexes (trigeminocardiac reflex, intubation)
- hyperkalemia
- consequences of anesthesia, including excessive depth, hypothermia, and hypoxia
what is the trigeminocardiac reflex
The trigemino-cardiac reflex (TCR) is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve in the maxilla.
can occur during root canals (tooth nerve removal) and in eye enucleations
sinus arrhythmia
sinus bradycardia
When the cause of bradycardia is increased
vagal tone, what should be administered
an anticholinergic (atropine)
Tachycardia and tachyarrhythmias in cats, HR?
HR >200 bpm in cats
Tachycardia and tachyarrhythmias in dogs, HR?
HR >160 bpm in dogs
A very large T wave can indicate what electrolyte imbalance?
hyperkalemia
3 most common Anesthetic-related causes of sinus tachycardia are:
¡ drugs (ketamine, anticholinergics)
¡ inadequate depth of anesthesia
¡ pain
sinus tachycardia
Premature ventricular contraction (extrasystoles):
Recurrent extrasystoles can be dangerous and need to be treated.
- treatment is Lidocaine iv
ventricular fibrillation
Anesthetics that cause a dose dependent drop in respiratory rate and depth
Opioids, propofol, alfaxalone, and inhalants can result in a dose dependent drop in respiratory rate and depth.
(Acepromazine and benzodiazepines cause minimal respiratory depression.)
Patient related mechanical causes of hypoventilation (3)
impaired respiratory muscle effort (rib fractures, pleural space disease, obesity)
upper airway obstruction common with
brachycephalic airway syndrome and tracheal collapse
True respiratory arrest may result from (3)
¡ anaesthetic overdose
¡ lack of oxygen flow
¡ preexisting disease
In this case, other vital signs are often abnormal and SpO2 values rapidly fall below 90%.
