General and Local Anesthetics Flashcards
Anesthetics
- drugs that eliminate pain by depressing nerve function in the central and peripheral nervous system
- produces a state of reduced neurologic function
General anesthesia (what happens)
- complete loss of consciousness and loss of body reflexes
- including paralysis of respiratory muscles
Local Anesthesia
no paralysis of respiratory function
Elimination of pain sensation in the tissues that are anesthetized
General anesthetics (route)
inhaled, parenteral
Overton-Meyer theory
- for all anesthetics, potency varies directly with lipid solubility
- fat-soluble drugs are stronger anesthetics than water-soluble drugs
- lipid-soluble anesthetic drugs can therefore easily cross the BBC to concentrate in nerve cell membranes
General Anesthetics (contraindications)
- pregnancy
- acute porphyria
- malignant hyperthermia
- monitor vital signs (sudden increase in temp, BP, HR), o2 saturation, ABCs, baseline labs
How do general anesthetics start taking effect?
- begins loss of senses (sight touch, taste, smell, hearing, consciousness
- cardiac and pulmonary are last to lose function because they are controlled by the medulla
- function returns in the opposite way
Malignant hyperthermia
- occurs during or after inhaled general anesthesia or use of NBD succinylcholine
- sudden elevation of the body tem (above 104F)
- tachypnea, tachy cardia, muscle ridifity
- life-threatening emergency
- treated with cardiorespiratory supportive care and dantrolene (skeletal muscle relaxant) reverses succinylcholine)
- at risk for anyone in the family who has had it before
General Anesthetics (adverse effects )
- in large doses life-threatening
- cardiac and respiratory suppression common
- use with caution on someone with beta-blockers or other meds that cause myocardial depression and antihypertensives with lower blood pressure
Dexmedetomidine (Precedex)
- provides sedation and analgesia without respiratory depression
- used for procedural sedation and surgeries of short duration. Also used in the ICU to sedate patients on mechanical ventilation
- short half-life
Ketamine
- used in both general anesthesia and moderate sedation
- can be given IM, IV, or SUbQ
- low incidence of cardiovascular or respiratory depression
Adverse effects: hallucinations
Nitrous Oxide
“laughing gas”
-used primarily for dental procedures or as a supplement for more potent anesthetics
Propofol (Diprivan)
- parenteral general anesthetic
- used for induction and maintenance of general anesthesia and for sedation in the ICU for mechanical ventilation
- can be used in lower doses for moderate sedation
- Adverse effects: can increase triglycerides because it is in a lipid-based emulsion
Moderate Sedation
- also called conscious sedation and procedural sedation
- does not cause complete loss of consciousness and does not normally cause respiratory arrest
- anxiety and sensitivity to pain are reduced, and the patient cannot recall the procedure
- preserves the patient ability to maintain own airway and to respond to verbal commands
- used for diagnostic procedures and minor surgical procedures that do not require deep anesthesia
- rapid recovery time and greater safety profile than general anesthesia
- combination of an IV benzodiazepine (midazolam) or propofol an opiate analgesic (fentanyl/morphine)
Local Anesthetics (route)
- topical: applied directly to skin or mucous membranes (creams, solutions, ointments, gels, ophthalmic drops, powders, suppositories
- parenteral: injected directly into the tissue or into the CNS by various spinal injection techniques
- spinal or intraspinal: intrathecal, epidural (regional anesthesia)
- nerve block (deep injection for the never root)
- infiltration (several small injections around area for anesthesia)
- peripheral nerve catheter attached to a pump containing the local anesthetic
Local Anesthetics (common names)
- lidocaine
- bupivacaine
- chloroprocaine
- mepivacaine
- prilocaine
- procaine
- propoxycaine
- ropivacaine
- tetracaine
Local Anesthetics (adverse effects)
“spinal headache”: happens in 70% of patients who experience inadvertent dural puncture during epidural anesthesia or intrathecal anesthesia (treated through bed rest, analgesics, maintain flat position for 6-12 hours, blood patch (injecting blood into epidural space), caffeine administration
- inadvertent intravascular injection: could be life-threatening
- slow metabolic breakdown
Neuromuscular Blocking Drugs
- prevent nerve transmission in skeletal and smooth muscle, resulting in muscle paralysis
- also paralyze the skeletal muscles required for breathing, the intercoastal and diaphragm
- used with anesthetics during surgery or to intubate
- when used during surgery, artificial mechanical ventilation is required
- can paralyze respiratory and skeletal muscles
- the patient cannot breathe on their own
- they do not cause sedation or pain relief
- the patient may be paralyzed yet conscious
Neuromuscular Blocking Drugs (NMBD; contraindications)
- malignant hyperthermia
NMBD (safety)
- emergency ventilation equipment must be immediately available
- constant monitoring during infusion (vital signs, o2 saturation, etc)
NMBD (common names)
- succinylcholine: attaches to ACh receptors and blocks the action of ACh
- Rocuronium: rapid to intermediate-acting
- Vecuronium: slower onset than rocuronium
