General Anesthesia Flashcards
Define anesthesia
What are the stages of anesthesia?
a combination of amnesia, analgesia, and muscle relaxation to allow the performance of surgery or other procedures
Stages
- Induction
- Maintenance
- Emergence
Stages of anesthesia: Induction
- AKA
- MC induction agent and effects
- other agents and effects
AKA
-“putting to sleep”
MC induction agent
-Propofol: causes drop in BP and CO, antiemetic properties
Other agents
-Etomidate: doesn’t cause vasodilation, higher rate of post op nausea, inhibits the biosynthesis of cortisol, use is limited d/t increased risk of death by 2.5x
-Ketamine: used in pts with hemodynamic instability, cardiac stimulant, significant analgesia, bronchodilation, hallucinations
Stages of anesthesia: Maintenance
- Use what types of drugs
- examples of these drugs
Use inhaled (volatile) or IV anesthetics
Inhalation anesthetic agents
- volatile anesthetic agents: sevoflurane and desflurane
- Nitrous oxide: can be used in combo with volatile gases
IV anesthetic drugs
-Propofol and remifentanil
Stages of anesthesia: Emergence
- AKA
- Can result in autonomic hyper-responsiveness, what are so signs and sx of this?
AKA
-Waking up
Autonomic hyper-responsiveness
- tachycardia, hypertension, bronchospasm, laryngospasm
- short acting narcotic, beta blockers, or lidocaine can blunt this autonomic response
IV Anesthetic Drugs: Propofol (Diprivan)
- Class
- onset of action
- duration
- use
- effects
- AE
Class
-Non-barbituate hypnotic agent
Onset
-40 seconds
Duration
- 1-3 hours
- rapid metabolized in the liver and excreted in the urine, so it can be used for long durations of anesthesia
Use
-general, cardiac, neuro, pediatric surgery
Effects
- some anti-emetic effects
- weaker amnestic effect than Versed
- NO ANALGESIC EFFECT
- clear headedness during recovery
AE
- can support rapid growth of microorganisms
- hypotensive (administer slowly)
- may cause hypertonia and movement
- resp depression
IV Anesthetic Drugs: Ketamine (Ketalar)
- Onset
- Duration
- frequently used in what patients
- effects
Onset
-30 sec
Duration
-5-10 min
Frequently used in
- pediatric pts because anesthesia and analgesia can be obtained with IM injection
- high risk geriatric pts and in shock cases because it provides cardiac stimulation
Effects
- affects the senses, produces a dissociative anesthesia (catatonia, amnesia, analgesia) in which the patient may appear awake and reactive, but cannot respond to sensory stimuli
- hallucinations
Anesthetic Gases
- name four
- where are these eliminated?
- what are the two shortest acting?
- how do inhaled anesthetics work?
- CI
Isoflurane (Forane)
Desfluorane (Suprane)
Sevofluorane (Ultane)
Nitrous Oxide
Eliminated in the lungs.
* the more soluble the gas is in the blood, the longer it takes to eliminate
Shortest acting: nitrous oxide and desflurane because they are the least soluble in the blood
Mechanism
- overall, they work on the CNS
- disrupt normal synaptic transmission by
- -interfering with the release of NT from presynaptic nerve terminal
- -alter the re-uptake of neurotransmitters
- -change the binding of NT to the post-synaptic receptor sites
CI
- inability to tolerate the physiologic alterations produced
- malignant hyperthermia (MH)
How are Anesthetic Gases dosed?
MAC (minimum alveolar concentration)
-the inhaled anesthetic concentration (steady state) at which 50% of patients move in response to a standard midline adb incision
Nitrous oxide=105%
Isoflurane= 1.15%
Sevoflurane= 1.8%
Desflurane= 6.2%
*MAC changes with age (the younger you are the more you need)
Anesthetic Gases: Isoflurane
- onset
- effects
- AE
Onset
-higher blood-gas solubility so takes longer for onset and longer for emergence
Effects
- tachycardia
- peripheral vasodilation
AE
- airway irritation
- coughing
Anesthetic Gases: Desflurane
- special administration requirements
- effects
- AE
- onset
Special admin requirements
-requires a heated-pressurized vaporizer for delivery
Effects
- tachycardia
- peripheral vasodilation
AE
-least well tolerated on the airway: coughing, bronchospasm
Onset
-fastest onset**** and off-set of volatiles
*not used for mask induction
Anesthetic Gases: Sevoflurane
- Onset
- effects
Onset
-fast onset and quick awakening
Effects
- does NOT cause tachycardia
- causes peripheral vasodilation
*well tolerated for mask induction
Anesthetic Gases: Nitrous oxide
- MAC
- disadvantages
- advantages
MAC= 105%, therefore NO alone cannot provide anesthesia
Disadvantages
- can diffuse into air containing cavities 34 times faster than nitrogen can leave that space…bloating in the bowel, middle ear, pneumothorax, cuff of ET tubes, etc.
- increased post-op nausea
- High MAC/ limits FIO2
- sympathomimetic
*has analgesic properties
Advantages
-inexpensive, readily available, odorless, limited effect, no special equipment, sympathomimetic, will not cause MH
Neuromuscular Blocking Drugs
- name five
- AKA
- what are the types?
Succinylcholine (Anectine)
Rocuronium (Zemuron)
Vecuronium (Norcuron)
Pancuronium (Pavulon)
Cisatracurium (Nimbex)
AKA
-Paralytics
Types
- depolarizing: Succinylcholine (Anectine)
- nondepolarizing: Rocuronium (Zemuron), Vecuronium (Norcuron), Pancuronium (Pavulon), Cisatracurium (Nimbex)
Neuromuscular Blocking Drugs: Depolarizing agents
- mechanism
- drug name
- DOC when what
- onset
- duration
- AE
Mechanism
- paralysis due to depolarization of the nerve terminal and the nerve being in a refractory state because the membrane is depolarized
- causes brief twitches or fasciculations, followed by flaccid paralysis
Drug
-Succinylcholine (Anectine): SLOWLY dissociated from the ACh
DOC
-when rapid control of the airway is necessary
Onset
-less than 1 min
Duration
-6-10 min
AE
- cardiac dysrhythmias
- sinus bradycardia
- myalgias
- myoglobinuria
- hyperkalemia
- masseter spasm
- MH trigger
- possible increases in intraocular, gastric, and intracranial pressures
- there are different genotypes for the metabolism of this med
- cant give to children
Neuromuscular Blocking Drugs: Nondepolarizing agents
- reversible or nonreversible
- fasciculations or no fasciculations
- what is the nest clinical marker of strength?
- name long-acting, intermediate-acting, and short acting
-Reversible competition between drug and ACh binding site
NO fasciculations (because they dont depolarize) -nerve stimulation exhibits a fade in train-of-four or tetany
Best clinical marker of strength
-sustained head-lift
Long acting
-pancuronium
Intermediate acting
- vecuronium
- rocuronium
- cisatracurium
Short acting
-mivacurium
