Anaesthetics Flashcards
1
Q
what is dental anesthesia
A
- medical procedure performed by applying drugs that cause loss of sensation
- local anesthesia: surface anesthetic; regional anesthesia
- general anesthesia
2
Q
what is local anesthesia
A
- loss of sensation to limited part of the body without loss of consciousness
- used for short term dental surgical/medical procedures
- applied by 5 major routes, route determined by location and amount of anesthesia needed
3
Q
what is the mechanism of action of anaesthetics
A
- act by blocking the entry of sodium ions into the neutron (sodium channel blockers)
- sodium influx needed for nerves to fire and conduct impulse
- non-selective blockade
- both sensory and motor impulses affected
- sensation and muscle activity decreased temporarily
4
Q
what are some special considerations for inflamed tissues
A
- low pH
- local anesthetic less effective
- never inject directly into infected, inflamed tissue (eg abscess) because the infection spreads
5
Q
what are adverse effects of anesthetic
A
- allergy rare and usually due to additives (sulphites and methylparaben)
- cardiovascular effects -> hypotension, dysrhythmias
- prevent adverse events by slow absorption or not inject directly into blood vessel
- may injure themselves by biting/chewing area in mouth with no sensation
6
Q
what are early signs of adverse events in anesthetics
A
- CNS stimulation -> restlessness and anxiousness
7
Q
what are later signs of adverse events in anesthetic
A
- CNS depression -> drowsiness, unresponsiveness
8
Q
what is lidocaine
A
- also called xylocaine
- most frequently used injectable local anesthetic
- 0.5% - 2% solution
- infiltration, nerve block, spinal, epidural, topical
- block sodium channels within membranes of neurons and cardiac tissue -> block nerve impulses
- onset 5-15 minutes for dysrhythmias
- solution with epinephrine only for local anesthesia not dysrhythmias
9
Q
how can lidocaine be applied
A
- injectable solution: plain (without EPI), with EPI
- topical: gel 10%, dentipatch (transoral delivery system)
- also used as a heart antiarrhythmic (intravenous)
10
Q
how can mepivicaine be applied
A
- injectable solution: 2% solution with vasoconstrictor (1:20,000 (54 mg) levonordefrin). 3% plain
11
Q
what is levonordefrin
A
- less potent vasoconstrictor than epinephrine but is more likely to cause an increase in blood pressure
12
Q
what is prilocaine
A
- injectable form: 4% with 1:200,000 epinephrine. 4% plain
13
Q
what is methemaglobinemia
A
- excessive methemoglobin levels (big word) reduce the amount of hemoglobin that is available for oxygen transport to the tissues
- cyanotic nails
14
Q
what is bupivicaine
A
- injectable: 0.54% solution with epinephrine 1:200,000
- lasts two or three times longer than lidocaine and mepivacaine, up to 7 hours
15
Q
what are cloves
A
- natural remedy for tooth pain = oil of cloves
- numbing effect
- works well with cavities
- soak cotton and pack around gums close to painful area
16
Q
what is anise
A
- natural remedy
- oil of anise for jaw pain caused by nerve pressure or gritting of teeth
- antispasmodic, relaxes intense muscle pressure around jaw angle, cheeks and throat
- also natural expectorant, cough suppressant, and breath freshener
17
Q
what are the components of local anesthetics
A
- epinephrine
- alkaline substances
- hydrochloride
- vasoconstrictors
18
Q
what does epinephrine do in anesthetics
A
- extends duration of action
- constricts BV in area -> anesthetic in area longer
- ie instead of 15-20 mins -> 45-60 min
19
Q
what do alkaline substances do in anesthetics
A
- alkaline substances such as sodium hydroxide or sodium bicarbonate added. neutralizes region, anesthetics more effective in basic environment. note: infected areas become acidified by bacteria
20
Q
what does hydrochloride do in anesthetics
A
- most anesthetics are combined with an acid such as HCl to form a salt because it is more stable and soluble (dissolvable) than the free base
21
Q
what do vasoconstrictors do in anesthetics
A
- local anesthetics cause vasodilation. vasoconstrictors added to local anesthetic, constrict the blood vessels in the tissue resulting in a decrease blood flow to the site of injury. slow the absorption of the agent into the bloodstream
- lower blood levels that decrease the risk of an overdose
- decrease or prevent bleeding (homeostasis) at the site of infection
- higher concentrations of the local anesthetic remaining in the nerve for a longer time (increase the duration of anesthetic effect)
- watch: EPI can cause hypertension followed by hypotension
22
Q
what are some examples of vasoconstrictors in local anesthetics
A
- epinephrine: infiltration, mandibular block
- levonordefrine (neo-cobefrin): fewer cardiac effects but more toxic effects
- contraindicated in patients taking psychotropic drugs
23
Q
what can go wrong with too much epinephrine
A
- excessive cardiac stimulation resulting in angina, cardiac arrhythmias, hypertensive crisis, and stroke
- in healthy patient EPI has no cardiac effects
- the maximum safe dose for epinephrine:
- in healthy individuals is 0.2 mg
- in cardiac patients is 0.04 mg
24
Q
what are the concentrations for epinephrine
A
- available in many concentrations: 1:50,000; 1:100,000 and 1:200,000
- concentration of EPI is increased from 1:100,000 to 1:50,000,
- alpha effect for local vasoconstriction increases
- the systemic beta effect increases
25
Q
what is levonodefrin
A
- less potent vasoconstrictor than EPI
- primarily stimulates alpha-adrenergic (sympathetic) receptors with little to no effect on the beta-adrenergic receptors
- stimulation of alpha-1 receptors on tissues/organs causes vasoconstriction of blood vessels resulting in hypertension (increase systolic and diastolic blood pressure)
- since it is less effective/potent than epinephrine it is used in higher concentrations (eg 1:20,000)
- mepivacaine 2% is available with levonordefrine
- onset of action is fast (30 to 120 minutes in the maxilla and 1-4 minutes in the mandible)
- duration of action is about 1 to 2.5 hours in the maxilla and 2.5-5.5 hours in the mandible
26
Q
topical forms of anesthetics
A
- lidocaine: gel, dentipatch
- benzocaine
- oraqix periodontal gel: lidocaine/prilocaine
27
Q
what should be done for anesthetic in children
A
- primary concern is the ease of overdose
- before administering a local anesthetic to a child: child’s weight used to calculate the appropriate dose
- in children under 10 years of age: usually no more than one-half cartridge of lidocaine 2% with epinephrine per procedure
- best to administer low-concentration solution such as 2% lidocaine with epinephrine 1:100,000
- bupivacaine should not be used because long duration of action
28
Q
what should be done for administering anesthetic for pregnant and nursing patients
A
- local anesthetics with vasoconstrictors can be used safely in pregnant and nursing women
- because of its low-concentration, lidocaine is preferred
- the concentration of vasoconstrictor is low so that there is unlikely any effect on uterine blood flow
29
Q
what should be done for administering anesthetic for the elderly
A
- no documented difference response to local anesthetics with vasoconstrictor – elderly vs younger adults
- best to administer below maximum recommended doses due to slower metabolism
30
Q
how to select the best anesthetic
A
- selection based on: duration of the dental procedure, amount of time pain control is required
- short procedure (especially involving mandibular block): solutions without vasoconstrictor such as mepivicaine of prilocaine plain
- longer procedure: bupivicaine has a long duration of action
- anticipation of post-op pain; choose a longer duration anesthetic to cover post op pain, like bupivicaine
31
Q
what do we use if epinephrine is contraindicated
A
- if epinephrine is contraindicated, use mepivicaine or prilocaine plain
32
Q
anesthetic selection for routine procedures
A
- use of epi is justified for most dental procedures
- lidocaine, articaine, prilocaine or mepivicaine
- children and pregnant patients: lidocaine with EPI
33
Q
what are most allergic reactions to in anesthetics
A
- preservatives
34
Q
what can happen when local anesthetics interfere with the CNS
A
- crosses the blood-brain barrier
- respiratory failure
35
Q
what are blood disorder concerns for anesthetics and what do we use for them
A
- methemoglobinemia
- use priolocaine or
- articaine, topicals benzocaine
36
Q
how can we treat toxicity caused by anesthetics
A
- monitor vital signs
- administer O2
- emergency operations
37
Q
how can we manage a medical emergency with a cocaine user
A
- do not administer EPI to a suspected cocaine addict for at least 24 hours after last use
38
Q
how can we manage a medical emergency for a hypertensive patient
A
- patient taking non-selective beta-blocker (eg propranolol, nadolol) for hypertension
- limit EPI dose to 2 cartridges (0.04 mg) of 1:100,000
39
Q
how can we manage medically compromised patients in the dental office
A
- patient taking cardioselective (beta 1) blocker, like atenolol, metoprolol for hypertension is no concern for epi
- no special precautions for using epi in patients with thyroid disease taking supplements
- monoamine oxidase inhibitors: antidepressant, ex isocarboxazid, phenelzine. no special precautions
- asthma/bronchitis: no special precautions using epi
40
Q
what is the dental management of patients with diabetes mellitus
A
- epinephrine increases blood glucose levels
- caution in uncontrolled diabetics
41
Q
what is the dental management of tricyclic antidepressants
A
- amitriptyline, desipramine, imipramine
- block reuptake of NE/EPI
- use EPI cautiously; no more than 2 cartridges of 1:100,000
- avoid levonordefrin
42
Q
what is the dental management of blood disorders
A
- prilocaine is contraindicated in patients with methemaglobinemia
43
Q
what is conscious sedation
A
- maintains the integrity of patient’s airway
- sedation (sleepiness)
- unaware of surroundings (narcosis)
- amnesia (loss of memory) or analgesia (increased pain threshold without loss of consciousness so the patient still responds to verbal (arousable) and physical stimuli)
- used in dental office
44
Q
what is minimal sedation
A
- anxiolysis
- drug-induced state during which patients respond normally to verbal commands
- ventilatory and cardiovascular functions are unaffected
45
Q
what is deep sedation
A
- induced state of depressed consciousness accompanied by partial loss of protected reflexes, including the inability to maintain an airway and/or respond to physical stimulation or verbal command
- hospital setting
- use of general anesthetics
46
Q
what is balanced anesthesia
A
- used where low doses of several drugs rather than one drug, with different actions are given
- minimize adverse events
- provide recovery of the protective reflexes within a few minutes of the end of the surgical procedure
47
Q
what are the different routes and types of administration for sedation
A
- enteral: absorption is through the GI tract (oral, rectal, sublingual)
- parenteral: absorption bypasses the GI tract (IV, IM)
- inhalation: gaseous or volatile drug is introduced into the lungs
- transdermal: drug is administered by a patch or iontophoresis
48
Q
how is general anesthesia obtained
A
- through IV and inhalation of drugs
49
Q
what is oral moderate sedation
A
- vie the enteral route
- common to use
- accepted by patients
- disadvantage: large initial dose and absorption not predictable
- combined moderate sedation via enteral and/or combination inhalation/enteral conscious sedation. more effective than either route used alone
50
Q
what is IV moderate sedation
A
- via parenteral route
- IV sedation does not mean dental anesthesia
- IV sedation is conscious sedation using IV agents
51
Q
what is inhalation sedation
A
- via inhalation via the lungs
- nitrous oxide/oxygen
- advantages – easy adjustment of depth of sedation and rapid recovery
- however, when nitrous oxide/oxygen is used in a ratio lower than 70:30, it is not as effective
52
Q
what is moderate sedation in dental office
A
- for apprehensive anxious patients
- reducing stress response
- some degree of amnesia
- not expected to induce depths of sedation that would impair the patient’s ability to maintain the integrity of his or her airway
53
Q
what is the intravenous moderate sedation
A
- intravenous anesthetics are mainly used for the rapid induction general anesthesia or moderate sedation
- maintained with an appropriate inhalation drug such as nitrous oxide-oxygen, or by intermittent or continuous infusion
- administered first to allay anxiety and fear
54
Q
what are intravenous anesthetics
A
- administered intravenously (directly into the blood)
- benzodiazepines take a few minutes to get to brain
- barbiturates take a few seconds
- benzodiazepines: diazepam (Valium), midazolam (Versed). amnesia effect and reducing apprehension and fear
- sedatives: barbiturates
- pentobarbital may also be used if the patient cannot take benzodiazepines
- sedative /hypnotics: nonbarbiturates such as propofol (Diprivan)
55
Q
what are IV moderate sedation drugs
A
- narcotic analgesics
fentanyl (sublimaze, duragesic, abstral, fentora, generics)
meperidine (demerol, generics) - analgesia (pain control) and euphoria & decrease benzo.
- varied responses in patients
- assess individual requirements
- provider must be prepared to intervene to rescue a patient’s airway
56
Q
when are oral agents used and what kinds are there
A
- for the fearful and apprehensive dental patient
- benzodiazepines:
- lorazepam (Ativan)
- midazolam (Versed)
- alprazolam (Xanax)
- diazepam (Valium)
57
Q
what is chloral hydrate
A
- sedative/hypnotic with little to no analgesic properties.
- safe drug when administered both orally or rectally for anxious children before a dental procedure.
- for sedation before and after surgery.
- given for conscious sedation and not for general anesthesia.
- sudden death can occur due to cardiac arrest
58
Q
how can we monitor patients during anesthetics
A
- important for the safety of patient
- recognize adverse reactions and emergencies
- assess patient for adequate airway and gas exchange and cardiovascular response
- vital signs
59
Q
what are some reversal agents
A
- benzodiazepine: flumazenil (Anexate) is a benzodiazepine antagonist and is given to patients to reverse the action of a benzodiazepine in cases of overdose.
- narcotics: naloxone (Narcan) is used in cases of narcotic overdose.
60
Q
what is nitrous oxide
A
- nonhalogenated
- first discovered in 1783 by Joseph Priestley
- laughing gas
- horace wells was the first dentist to use nitrous oxide
- it is a weak anesthetic agent with marked analgesic (pain-free) and amnesia (loss of memory) propertie
- stage I surgical anesthesia
- helps to allay anxiety to dental treatment for many patients
- ideal for dental procedure; patient remains conscious and can follow instructions while having full analgesia
- nitrous oxide has a rapid action (2 to 3 minutes) without loss of consciousness and a rapid recovery
- the average patient requires 35% of nitrous oxide in oxygen with a range of 10-50%
50% mixture in oxygen for analgesic - easy to administer and can be self-delivered by the patient using the demand-valve positive pressure method
- used in balanced anesthesia
61
Q
what are indications for using nitrous oxide
A
- fearful, anxious patient
- cognitively, physically, or medically compromised patient
- gag reflex interferes with oral health care
- when profound local anesthesia cannot be obtained or tolerated
62
Q
what are adverse effects of nitrous oxide
A
- nausea, vomiting
- avoid heavy meal 3 hours before
- chronic exposure
- fall in the white-cell count and neuropathy (nerve damage including numbness of limbs)
- exposure of anesthetists or other operating room personnel to nitrous oxide should be minimized
63
Q
what are side effects of nitrous oxide
A
- adverse events uncommon if low to moderate doses
- signs of stage 2 anesthesia (anxiety, excitement, combativeness) as dose increases
- temporary difficulty breathing at end
- nausea and vomiting following procedure
- subject to abuse (relaxed, sedated state)
64
Q
what are some possible drug interactions for nitrous oxide
A
- nitrous oxide interacts with vitamin B12, resulting in megaloblastic anemia
- additive sedative effect with other sedative drugs and St. John’s wort
- does not cause respiratory depression, bronchodilation, or low blood pressure
65
Q
what are contraindications for nitrous oxide
A
- no significant clinical drug interactions occur with nitrous oxide.
- do not use in patients with the following conditions:
- coronary heart disease
- chronic obstructive pulmonary disease (e.g., bronchitis or emphysema)
- respiratory obstructions (e.g., stuffy nose, blocked Eustachian tubes)
- pregnancy
66
Q
what are some hazards to operating room personnel regarding nitrous oxide
A
- faulty equipment can pose a hazard for dental/medical clinicians in the room, especially spontaneous abortion and genetic effects
- scavenging devices are necessary to avoid exposure of gas to the surrounding clinicians
67
Q
what should we be teaching clients regarding anesthetics
A
- topical anesthetics, avoid touching eyes
- never apply topical meds to large patches of skin or to open lesion/cut
- inform dentist if had adverse rxn in past
- not to eat/drink until anesthetic worn off
- do not chew or pick at area while still numb
- do not inhale anesthetic topical sprays
- after local, immediate assistance if drowsy, confused, blurred vision, lightheadedness, irregular heartbeat, feeling faint
- risk if pregnant, seizures, other meds
- have someone assist/drive after procedure
- follow caregivers instructions after anesthesia
- have sufficient pain meds to treat Sx after procedure
68
Q
what is the dosing of articaine in children
A
- 5mg/kg
69
Q
what is the dosing of bupivicaine in children
A
- 2 mg/kg
70
Q
what is the dosing of lidocaine in children
A
- 7 mg/kg
71
Q
what is the dosing of mepivicaine in children
A
- 6.6 mg/kg
72
Q
what is the dosing of prilocaine in children
A
- 8 mg/kg
73
Q
converting lbs to kg
A
- 1 lb = 2.2 kg
