Injectable anesthetics Flashcards
Which injectable anesthetics uses:
Intravenous anesthetic — causing CNS depression ranging from drowsiness and mild sedation to coma
Control convulsive seizures by — depressing motor areas of the brain
barbiturates
Which injectable anesthetics has this effect on vital systems:
- May profoundly depress respiration; degree is related to the dose and rate of drug administration.
- Apnea may result from rapid administration of high doses
- Significant cardiovascular depression (seen in the first 10 minutes after IV injection)
- Cardiac output and heart rate initially rise then decrease
barbiturates
Other effects of this injectable anesthetics:
Excessive salivary secretion — coughing, hiccoughing, laryngospasm
Readily cross the blood-placental barrier causing respiratory depression of fetuses
Tissue irritation – bc highly alkaline and may cause tissue irritation when injected perivascularly
Excitement during induction and recovery
Increased potency in hypoproteinemic animals
Increased potency and duration of action in very thin animals including Sighthounds
barbiturates
Identify the barbiturate (acc. to duration of action):
5-15 mins
— used to induce patients to surgical anesthesia
ultrashort-acting barbiturate
Example of ultrashort-acting barbiturate
Methohexital Na
Identify the barbiturate (acc. to duration of action):
45 mins to 1.5 hours
—used to produce general anesthesia
short-acting barbiturate
Example of short-acting barbiturate
Thiopental Na (Pentothal Na)
Identify the barbiturate (acc. to duration of action):
— 2 to 6 hours
Intermediate acting barbiturate
Example of Intermediate barbiturate
Pentobarbital (Nembutal Na)
Identify the barbiturate (acc. to duration of action):
8-12 hours
— not used as anesthetics
— anticonvulsants in humans
long-acting barbiturate
example of long acting barbiturate
phenobarbital
MOA of this injectible anesthetics
- Disruption of nerve conduction pathways within the cerebrum and stimulation of the reticular activation center of the brain.
- Suppress inhibitory neurons —> selective CNS stimulation —> dissociative anesthesia or catalepsy
Cyclohexamines
the state where there is malleable rigidity of the limbs and the patient appears awake but is dissociated from or unaware of the environment; the animal tends to remain in any position of placement.
Catalepsy
Provides significant analgesia to the skin but poor visceral and limb anesthesia
Cyclohexamines
Injectable anesthesia that has this effects on vital systems:
- Does NOT produce cardiorespiratory depression
- Most animals exhibit tachycardia and elevated blood pressure
- Animals exhibit apneustic breathing pattern in which the patient hold its breath for several seconds at the end of the inspiratory phase, which is followed by a quick expiratory phase.
Cyclohexamnes
Other effects of this injectable anesthetics:
- May cause tissue irritation when given IM but do not cause tissue necrosis.
- Stimulates salivation and increase tracheo-bronchial mucous gland secretions
- May increase cerebrospinal fluid pressure and intraocular pressure
- Eye remains open with a central and dilated pupil
- May induce nystagmus (repetitive side-to-side motion of the eyeball)
- Recovering animals often show an exaggerated response to touch, light and sound
- Seizure-like activity and bizarre behavior may also be observed during recovery
Cyclohexamines
Injectable anesthetics that have this contraindications:
- Animals with history of seizures
- Animals that have ingested strychnine, metaldehyde, marijuana, organophosphates and other toxins that affect the CNS
Cyclohexamines
Identify the injectable anesthetics:
- Combination of an opioid and tranquilizing agent can also be used to induce general anesthesia in dogs when given by IV injection
- Not suitable for routine induction of anesthesia in healthy, young dogs
- May have a profound effect in high-risk or debilitated dogs and are useful and safe alternative to barbiturates or ketamine induction in these animals
- Seldom used to induce anesthesia in cats because of unacceptable side effects (excitement, mania)
- Rapid injection may cause CNS stimulation and profound respiratory depression
Neuroleptanalgesia
Identify the injectable anesthetics:
- an ultrashort-acting, non-barbiturate IV anesthetic
- Dilution with saline or 5% dextrose in water allows more accurate dosing and helps to prevent respiratory and cardiovascular side effects in small animals
- In dogs, recovery is rapid and smooth, even with multiple injections
Propofol
Injectable anesthetics that has this clinical uses:
- Sole agent for brief procedures or for anesthetic induction before intubation and inhalant anesthesia
- Maintenance of general anesthesia when combined with opioid analgesics or other sedative or other sedative-analgesic drugs
Propofol
Injectable anesthetics that has this effect:
- Transient excitement and muscle tremors during induction
- Overall cardiovascular and pulmonary effects similar to barbiturates
- Minimal analgesia
- Moderate muscle relaxation
- Decreases intracranial and intraocular pressure
Propofol
Identify the injectable anesthetic:
- Rapid-acting, ultrashort, IV anesthetics
- Sedative/hypnotic imidazole drugs that are occasionally used for induction of anesthesia in the cats and dogs
- Anesthesia is characterized by good muscle relaxation without analgesia
etomidate / metomidate
Clinical uses of this injectable anesthetics:
- short term (5-10 minutes) anesthesia in the dog and cat
- induction agent of choice for difficult cardiac cases and animals in shock because of its minimal effect on cardiovascular functions
etomidate / metomidate
Injectable anesthesia that has this effects:
- Mild respiratory depression, transient apnea
- produces good muscle relaxation
- IV injection is painful and may cause phlebitis
- Rapid injection may cause RBC hemolysis in cats
- Nausea, vomiting, and involuntary excitement may occur during induction or recovery, particularly in patients that have not been adequately premedicated.
etomidate / metomidate
