38 terms

Anesthesia

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What is the mechanism of action for Succinylcholine?
Depolarizing Muscle Relaxant - mimics ACh causing prolonged depolarization at the NMJ and paralysis secondary to blocked ACh receptors
What is the intubating dose for Succinylcholine?
1-1.5 mg/kg
How fast is the onset for Succinylcholine?
30-60s
How long does Succinylcholine last?
3-5 minutes
How is Succinylcholine metabolized?
Plasma cholinesterases
What are the indications for using Succinylcholine?
- Rapid Sequence Induction
- Short procedures (small)
- Laryngospasm
What are the side effects of Succinylcholine?
- stimulates muscarinic as well as nicotinic, so can result in bradycardia, dysrhythmias
- hyperkalemia (stimulation leads to massive release of potassium from muscle cells)
- triggers MH
- increases ICP
- fasciculations (can be minimized by using roc)
Contraindications to Succinylcholine
Absolute:
- history of above complications
- myotonia
Relative:
- plasma cholinesterase deficiency
- myaesthenias
Mechanism of action of Ketamine?
Phenylcyclidine derivative - acts on opioid, NMDA, other receptors
What are the effects of Ketamine to the CVS, CNS, and respiratory system?
- Increased HR, BP, SVR, coronary flow, myocardial O2 demand
- CNS depression, respiratory depression, bronchial smooth muscle relaxation
What are the indications of Ketamine?
Used for induction in:
- Major trauma, hypovolemia
- severe asthma
Contraindications to Ketamine?
- allergy
- tricyclic antidepressants
- psychosis
- people who cant tolerate HTN
Dosing of Ketamine?
1-2 mg/kg
Timeline of Ketamine activity?
- Dissociation in 15s, analgesia+amnesia+anesthesia in 60s
- unconscious for 10-15m, analgesia for 40 min, amnesia for 2 hours
Complications of Ketamine?
- High incidence of emergence reactions
Mechanism of action of Propofol?
- inhibitory @ GABA synapse
What are the effects of propofol on the brain and CVS?
- decreased cerebral metabolic rate + blood flow, decreased ICP
- decreased SVR, decreased BP (0-30%), decreased SV
What is Propofol used for?
- most cases of induction
- maintenance - Total Intravenous Anesthesia
What are contraindications for propofol?
- patients who can't tolerate sudden decreased BP (fixed cardiac output like in aortic stenosis, shock)
What is the dosing for propofol for IV induction?
2.5-3.0 mg/kg, less with opioids
How quickly does propofol act and how long does it last for?
Unconscious <1 minute, lasts 4-6 minutes, half-life 55 minutes
What are advantages to propofol?
- decreased post-op sedation
- decreased recovery time
- decreased N/V
What is the mechanism of action of Thiopental?
- decreases time that chloride channels open, facilitating GABA and suppressing glutamic acid
What is Thiopental's effect on the brain, CVS, and respiratory systems?
- decreased cerebral metabolism + blood flow, decreased cerebral perfusion pressure
- decreased CO, BP, reflex tachycardia
- decreased respiration
What are the indications for thiopental?
- Induction for control of convulsive patients and obstetric patients
- not used for maintenance
What are contraindications to using Thiopental?
- Allergy
- uncontrolled hypotension/shock/cardiac failure
- Porphyria
- liver disease
- status asthmaticus
- myxedema
What is the dosing for induction of Thiopental?
Induction: 3-5 mg/kg
What is the timeline for anesthesia using Thiopental?
- Unconscious for 30s, lasts 5 minutes, accumulation with repeat dosing
- halflife 5-10 hours
- post-operative sedation lasts hours
What are complications of thiopental?
- decreased BP
- post-operative sedation
- combining with rocuronium causes precipitates to form
What is the mechanism of action of benzodiazepines?
- increased glycine inhibitory neurotransmitter, facilitating GABA
What is the effect of benzodiazepines on skeletal muscle, the brain, and CVS?
- skeletal muscle relaxation
- anxiolytic
- cardiac depression (minimal)
What are the indications for use of Benzodiazepines?
used for sedation, amnesia, anxiolysis
What is the mechanism of action of Etomidate?
Decreases concentration of GABA required to activate receptor
What are the effects of Etomidate on the CNS and CVS?
CNS depression
minimal cardiac/respiratory depression
What are the indications for Etomidate use?
- Induction with presence of poor cardiac function, severe valve lesions, and uncontrolled hypertension
What are the complications of etomidate?
- Post-operative N/V, venous irritation
- cannot repeat first dose or use as infusion
- adrenal suppression
- myoclonic movements during induction
What is the induction dosing for etomidate?
0.3 mg/kg
What is the timeline for the effects of etomidate?
onset - 30-60s
lasts 4-8 minutes