General Anesthesia Flashcards
Physiological affect of General Anesthesia
Decreases systemic arterial BP
IV Anesthetic Agents
- Barbiturates
- Propofol
- Etomidate
- Ketamine
Barbiturates
- Sodium thiopental (most common)
- Thiamylal (veterinarian use only)
- Methohexital
Standard Practice of Barbiturates
Delay administration of other drugs until the barbiturate has cleared the IV tubing
Barbiturate Side Effects
- Suppression/burst suppression of EEG
- Reduce cerebral metabolic rate
- BP reduction
- Respiratory depression
Propofol MOA
Agonist actions on GABA A receptors
Propofol Adverse Effects
- Pain at the injection site
- Hyperlipidemia
How should propofol be administered?
Within in 4 hours of its removal from sterile packaging o/w throw it out
Fospropofol
- Prodrug of propofol
- Does not have the adverse effects propofol does
- Indicated for sedation in patients undergoing diagnostic procedres
- new aqueous form of propofol
Propofol Metabolism
- Metabolized in the liver
- Excreted from the kidneys
- Some may also be excreted through the lungs
- Clearance is reduced in elderly and neonates
- Clearance is faster in bigger people (more central volume)
Propofol Side Effects
- Increased Chloride conduction
- Hyperpolarization of neurons
- Suppressed EEG
- Burst suppression EEG
- Provokes anaphalactoid reactions
Does propofol have clinically significant effects on the hepatic, renal, or endocrine organ systems?
NO
it does have anti-emetic actions though
What is Etomidate primarily used for?
Anesthetic induction of patients who are at risk for hypotension
What is Etomidate a/w?
- Pain on injection (use lidocaine)
- Myoclonic movements (pre medicate with benzos or opiates)
Etomidate Side Effects
- May induce hiccups
- May reduce cortisol levels
- Can cause vomiting
- Can lower the seizure threshold
What is an advantage of Etomidate over barbiturates and propofol?
Cardiovascular stability after induction
What is ketamine used for?
Anesthetizing patients at risk for hypotension and bronchospasms and good for certain pediatric procedures
How do you administer ketamine?
- Mainly IV
- IM
- Oral
- Rectal
Ketamine Side Effects
- Rapidly produces a hypnotic state
- Hallucinations
- Emergence delirium
- Increased ICP
- Increased CO
- HTN
What is the only inhalation anesthetic that does cause malignant hyperthermia?
NO
What happens with incr lipid solubility?
slower induction, longer maintenance and longer recovery
What happens with decreased lipid solubility?
quicker induction, less maintenance, and shorter recovery
How are inhaled anesthetics eliminated?
Reverse process of uptake
Halothane
- Incr Lipid solubility
- Used mostly in children (diminished side effects)
Halothane SE
- Inhibits hypoxic pulmonary perfusion
- Relaxation of skeletal muscle
- May cause malignant hyperthermia
Is Isoflurane as lipid soluble as Halothane?
No.
Does Isoflurane have analgesic effect?
No
Is Isoflurane commonly used?
Yes
What is Isoflurane mostly used for?
Maintenance after induction
What reduces concentration of Isoflurane?
Opioids (they are needed for analgesia)
Isoflurane SE
- Concentration dependent depression of ventilation
- Incr ICP
- W/ incr dose Splanchnic and hepatic blood flows are reduced along with systemic arterial pressure
Is cardiac output well maintained with Isoflurane?
Yes
What is Enflurane mainly used for?
- Maintenance
- Can achieve anethesia
Enflurane SE
- Hypotension
- Greater ventilator depression
- Increase cerebral pressure (cerebral vasodilator)
- Mild to moderate liver injury (rare)
How fat soluble is Desflurane?
Not very
How does does it take alveolar concentration to reach 80% with Desflurane?
5 mins (quick induction and recovery)
When is Desflurane mostly used for?
Out pt surgury
Is Desflurane used for induction?
Hell no! Strong airway irritant (coughing, breath holding and so on)
Desflurane cardiac effect
Cardiac output is well preserved
Sevoflurane Lipid Solubility?
Low (Rapid induction)
What is Sevoflurane inidcated for?
- Induction and maintenance
- Out pt due to rapid recovery
Sevoflurane SE
- Reduction of tidal volume
Nitrous Oxide
- Weak anesthetic
- Significant Analgesic effect
NO SE
When administered alone it can significantly incr cerebral blood flow and intracranial pressure
Why are Benzos used?
- anxiolysis
- amnesia
- sedation
What are the most frequently use Benzos perioperative? (In order of whats used most first)
- Midazolam
- Diazapam (valium)
- Lorazapam (Ativan)
What is an example of an Alpha Adrenergic Agonis?
Dexmedetomidine (Precedex)
What is Dexmedetomidine indicated for?
Short term (<24hrs) sedation of critically ill or sedation in non intubated pts
What does Dexmedetomidine provide?
Provides analgesia with little respiratory effects
Dexmedetomidine SE
- Hypotension
- bradycardia
- n/v
What is the only effective analgesic?
Katamine
What is the only opioid NOT metabolized in the liver?
Remifentanil (Ultilva)
Name one depolarizing neuromuscluar blocking agent
Succinylcholine
Succinylcholine SE
- ***Incr Serum K
- ***Malignant Hyperthermia
- Incr intra-ocular pressure
- Incr Intragastric Pressure
- Prolonged paralysis
How does succinylcholine work?
Directly blocks the nicotinic receptors with an initial activation
Name one non-depolarizing neuromuscluar blocking agent
Vecuronium
How does Vecuronium work?
Directly blocks the postsynaptic nicotinic receptors with no activation
How can you stop the effects (muscle paralysis is no longer desired) of Vecuronium?
Give anticholinesterase inhibitor
- neostigmine or endrophonium
