Exam II Lecture 6 Flashcards
1
Q
what are the two categories of inhaled anesthetics?
A
- volatile - liquids or solids at room temp
- gaseous - gas at room temp
2
Q
what are the 5 types of volatile anesthetics?
A
halothane, enflurane, isoflurane, desflurane, sevoflurane
3
Q
what is an example of a gaseous anesthetic?
A
nitrous oxide
4
Q
what are the desirable qualities of inhaled anesthetics?
A
- Rapid induction (onset)
- Rapid termination (elimination)
- Effect compartment- the location you are trying to effect (in this case, CNS)
5
Q
what are factors that control the uptake of nitrous oxide?
A
- Inspire concentration of gas
- Ventilation
- Solubility of gas
- Cardiac output
6
Q
the partial pressure of O2 in alveolus is around ___ mmHg
A
103
7
Q
the partial pressure of O2 in capillaries is ___ mmHg
A
40
8
Q
what is the onset of action of nitrous oxide for the following routes of administration: oral, rectal, IM, IV, and inhalation
A
- oral - 30 min
- rectal - 30 min
- IM - 10-15 min
- IV - 20 seconds
- inhalation - less than 20 seconds
9
Q
is nitrous oxide soluble in the blood?
A
no, so it really isn’t metabolized in the body
10
Q
what is the peak clinical effect of nitrous oxide given the following routes of administration: oral, rectal, IM, IV, and inhalation
A
- oral - 60 min
- rectal - 60 min
- IM - 30 min
- IV - 60 sec to 20 min
- inhalation - 3-5 min
11
Q
describe the depth of sedation of nitrous oxide when give through the following routes of administration: oral, rectal, IM, IV, and inhalation
A
- oral - cannot easily deepen or lighten sedation
- rectal - cannot easily deepen or lighten sedation
- IM - cannot easily deepen or lighten sedation
- IV - sedation level may easily be deepened; however, lessening of sedation is difficult to achieve
- inhalation - sedation levels easily changed either way
12
Q
what is the duration of nitrous oxide given the following routes of administration: oral, rectal, IM, IV, and inhalation
A
- oral - 2-3 hours
- rectal - 2-3 hours
- IM - 2-4 hours
- IV - 45 min to 4 hours
- inhalation - at discretion of administrator
13
Q
what is the recovery time of nitrous oxide given the following routes of administration: oral, rectal, IM, IV, and inhalation
A
- oral - not entirely complete even after 2-3 hours
- rectal - not entirely complete even after 2-3 hours
- IM - not entirely complete even after 2-3 hours
- IV - not entirely complete even after 2-3 hours
- inhalation - usually complete following 3-5 minutes of inhalation of 100% O2
14
Q
diffusion hypoxia is called the ___ effect
A
hangover
15
Q
how can diffusion hypoxia occur?
A
if pt breathes room air at the conclusion of N2O-O2 sedation, the gas rushes to the lungs and CO2 is removed from the lungs, causing respiratory depression, resulting in hypoxia
patient will be lethargic and naseous (“hangover effect”)
16
Q
how is diffusion hypoxia prevented?
A
by breathing 100% O2 for 5 minutes at the termination of the procedure
17
Q
titration of nitrous oxide is possible via which of the following routes of administration: oral, rectal, IM, IV, inhalation
A
IV and inhalation only
18
Q
when administered nitrous oxide during a dental procedure, can the patient be discharged from the office following a procedure with no prohibitions on activities?
A
yes
19
Q
are injections required to administer nitrous oxide sedation, or to reverse it?
A
no
20
Q
are they many side effects of nitrous oxide?
A
no, there are very few side effects
21
Q
what are the effects N2O has on the liver, kidneys, brain, or cardiovascular and respiratory systems?
A
no adverse effects
22
Q
N2O has ___ properties, which allow it to be used instead of local anesthesia in certain procedures
A
analgesic
23
Q
is the initial cost of N2O equipment expensive?
A
yes, and it is expensive to maintain
24
Q
does equipment for N2O conserve space?
A
no, it occupies considerable space
25
N2O is a ___ agent, and failures can occur
potent
26
T or F:
cooperation is not required from a patient in order for N2O to be delivered effectively
false
the patient must be able to inhale gases through their nose
27
in order to legally administer N2O, the administrator must receive ___ hours of training
14
28
unscavenged trace nitrous oxide can be \_\_\_
deleterious
29
what are the indications for N2O sedation?
* The Management of Fear & Anxiety
* The Medically Compromised Patient
* The Management of Gagging
30
what are the effects of N2O administration on patients with cardiovascular disease?
* Lower anxiety means lower myocardial ischemia
* Oxygen administration
* Analgesic effect of N2O
31
what are the effects of N2O on patients with respiratory disease?
* Administered safely to asthmatic patients
* N2O is non-irritating to tracheo-bronchial tree
* Increased stress is potential cause of acute exacerbation of asthma.
* May not work with chronic nasal obstruction
* Relative contraindication with COPD
32
what are the effects of N2O on patients with cerebrovascular disease (stroke)?
* Reduced anxiety helps reduce blood pressure
* Previous stroke patients unable to tolerate O2 levels below normal without risk of seizure. Since elevated level of O2 routinely provide to patient, N2O-O2 sedation is major technique indicated for these patients.
33
what are the effects of N2O on patients with liver disease?
* Most sedative drugs require biotransformation in the liver.
* N2O does not undergo biotransformation within the body & is exhaled intact.
34
what are the effects of N2O on patients with epilepsy and seizure disorders?
* Increased stress & anxiety help precipitate seizures
* N2O is non-epiliptogenic (does not induce seizures)
* Epileptics more sensitive to hypoxia
35
what are the effects of N2O on pregnant patients?
* Absolutely contraindicated in 1st trimester
* N2O crosses the placenta - produces the same degree of CNS depression in the fetus as in the mother
* Should consult obstetrician
* can cause spontaneous abortion
36
have allergies every been reported with the use of N2O?
no
37
is N2O contraindicated with pateints with diabetes?
no
38
what are the considerations for N2O use with gagging patients?
* Effective in eliminating/minimizing severe gagging.
* May require placing patient in upright position
* Practical for use in short procedures such as Radiographs or Impressions.
39
what patients is N2O contraindicated?
* compulsive personality
* claustrophobic patient
* children with behavior problems
* patients with severe personality disorders
* respiratory tract infection
* potentially cantagious diseases
* COPD
* pregnant patients
40
why is it a concern to administer N2O to someone with a compulsive personality?
don't like the feeling of losing control; tend to fight the effects of N2O
41
why is it a concern to administer N2O to a claustrophobic patient?
unable to tolerate nasal hood; don't use nasal cannula - scavenge
42
why is it a concern to administer N2O to a child with behavior problems?
requires a degree of cooperation; screaming, crying, moving about causes mouth breathing
43
why is it a concern to administer N2O to a patient with a severe personality disorder?
although no drug interactions with psychotropic drugs, may be prudent to avoid altering consciousness of people who have only a tenuous grip on reality
44
why is it a concern to administer N2O to someone with a respiratory tract infection or other potentially contagious disease?
these conditions contaminate tubing and rubber goods, so these patients should have their own disposable rubber goods to minimize risk of cross contamination
45
why is it a concern to administer N2O to someone with COPD?
* stimulus for breathing is a lowered O2 content, so a higher O2 content may cause apnea
* can use pulse oximeter and monitor respiratory rate
46
normally, the O2 saturation level is at \_\_\_%. for patients with COPD, it can reach as low as \_\_\_%, which can only be tolerated for a short amount of time. in any situation, you don't want the O2 saturaiton level to reach \_\_\_% or below.
* 95%
* 89%
* 94%
47
why is it a concern to administer N2O to a pregnant patient?
* Avoid during first trimester – slight increase in spontaneous abortion & fetal malformation
* Safe during 2nd trimester
* 3rd trimester avoid if close to birth.
* In emergency situation, N2O-O2 sedation is safest form of sedation.
* Often used during labor & delivery.
48
how is N2O prepared?
* Prepared through heating of ammonium nitrate crystals which decomposes into N2O & H2O.
* Chemically scrubbed to remove impurities, acids & alkaline. NO is most dangerous impurity, combine with hemoglobin, prevent absorption of O2.
* Compressed in metal cylinders.
49
is N2O irritating? what does it smell like? what color is it?
non-irritating, sweet smelling (actually odorless...), and it is a colorless gas
50
what state is N2O in when it is in the cylinders?
as a liquid in cylinders under pressure, then returns to gaseous state as it is released from the cylinder
51
describe the potency of N2O compared to other anesthetic gases
it is the least potent; unable to achieve surgical-depth anesthesia unless combined with more potent agent (second gas effect)
52
N2O has great ___ variability
biological
53
what is the systemic effect of N2O-O2 on the central nervous system?
slight depression of sight, hearing, touch, memory, concentration & pain. Postrema (vomiting center) not affected.
54
what is the systemic effect of N2O-O2 on the cardiovascular system?
no changes in heart rate or cardiac output. Slight depression of myocardial contraction. Some flushing & perspiration.
55
what is the systemic effect of N2O-O2 on skeletal muscle?
no muscle relaxation
56
what is the systemic effect of N2O-O2 on the reproductive system?
spontaneous abortion & fetal malformation slight increase with chronic short term exposure. Fertility is decreased with long term exposure.
57
Chronic exposure to high levels of N2O is capable of producing a ___ that can be extremely debilitating. This is usually limited to persons who have \_\_\_.
* sensory neuropathy
* purposefully abused the drug
58
what is included in nitrous oxide equipment?
* Flow meters - measures motion of gas (not in the cylinders)
* Reducing valves
* Gas cylinders
* Reservoir bag
* Conducting tubing
* Nasal hood
59
for gas cylinders, which color corresponds to N2O, and which color corresponds to O2?
* blue - N2O
* green - O2
60
what should be monitored during N2O inhalation sedation?
* Baseline vital signs, preoperatively
* Verbal communication with patient
* Vital signs recorded periodically during the procedure
* Postoperative vital signs.
61
what monitors are used during inhalation sedation?
pulse oximetry, ECG, and precordial stethoscope
62
what is the purpose of the reservoir bag?
* provides reservoir for which additional gas can be draw
* in its absense, the patient may feel suffocated when the hood is in place
* used as a monitoring device for breathing - will see it inflate and deflate with the patients breathing
* when it is in use, it is blown up to twice its size; when not in use, it is deflated
* can also be used as a forced compression system
63
what is the protocol for patient preparation on the day of their appointment where N2O will be administered?
* Request patient visit restroom and void if necessary. More urine produced when supine.
* Review medical Hx & record preop VS before starting N20-02. Include BP, HR, Rhythm & Respiratory Rate.
* remove contact lenses, if worn. gas leaks produce drying of eyes
64
what are the 13 steps for administration of N2O?
1. position patient in a comfortable, reclined position
2. position a portable inhalation sedation unit behind the patient, out of line of site
3. Nasal hood is placed on patient.
•Many breathe thru mouth if not reminded.
4. Secure Nasal Hood.
5. determine proper flow rate for the patient
6. observe reservoir bag
7. titrate N2O
8. observe the patient
9. continue titration of N2O and observe the patient
10. begin dental treatment
11. continue observing patient and inhalation unit during the procedure
12. terminate flow of N2O
13. discharge patient and cleanse the equipment
65
when positioning a patient for administration of N2O, upright position in only recommended for ___ and \_\_\_, otherwise a reclined position is recommended
impressions and radiographs
66
when the nasal hood is placed on the patient, should they be able to move their head?
yes, they should have some lateral and up & down movement
67
how can leaks through the nasal hood be prevented?
adjust the tube clip to tighten the tubes, or use 2x2 gauze
68
what is the proper flow rate for adults? what about children?
* adults - 6L/min flow of 100% O2 for adults
* 3-4L/min for smaller pediatric patients
69
when N2O is administered, should the patient feel as though the volume of air they take in a normal breath is inadequate?
no, it should fee adequate
* some patients require large flows: COPD, endurance sports, heart failure, partial nasal obstruction
* ask patient if they can breath normally; if not, increase flow at 1L/min increments
* may need higher flow rates at the beginning, especially if it's the patient's first time
70
the reservoir bag can be observed to determine what?
respiratory depth and rate, also seal
71
what are two possible causes of the reservoir bag being overly inflated?
* minute volume is too great
* hose is kinked (occluded); inability to breath comfortably
72
what are the two methods of N2O administration? what is the initial %N2O for each type?
* Constant Liter Flow – total liter flow of gases per minute kept constant & percentage (N20/02) adjusted. Our units (mixing dial).
* Constant Oxygen Flow – O2 flow kept constant & volume of N20 adjusted. Need separate control knobs of N20 & 02 flows. More difficult calculation. Make mistakes. Common misconception, flow of N2O equals % of gas, eg: 2L/min =20%.
* Both types, initial % N20 is 20%
73
after the first titration of N2O, what should you observe your patient for?
* Start at 20% N20 looking for signs & symptoms of sedation.
* At end of 60-90 second period, ask “What are you feeling?” Open-ended question.
* At this % usually little or no effect so titration continues; bump up to 30%.
* Check to see that patient’s legs are uncrossed. Patients rarely move when sedated and lack of circulation could cause parethesia or hyper-esthesia.
74
after initial titration and patient observation, what should you be looking for as you continue titration of N2O and patient observation?
* Every 60-90 seconds increase nitrous 5-10 % until S & S of sedation appear.
* Lightheadedness: Usually the first effect. Some say dizziness (uncomfortable?). Tell pt. this is normal & will pass as N20 increases. This usually develops at stage that is clinically inadequate for management of most patients.
* Tingling (paresthesia) of arms, legs or mouth. Symptom develops at level still inadequte to permit ideal management of fearful patient.
* Warmth, floating, heaviness: ideal level. Patient relaxed & comfortable. Congratulations, you’re there!
75
what is a sign and symptom of oversedation?
nausea (symptom)
vomiting and loss of consciousness (signs)
76
what should you do if your patient begins to perspire heavily & feel uncomfortable? Decrease N20 5%, attempt to decrease perspiration w/o altering level of sedation. Technique for Oversedation.
Decrease N20 5%, attempt to decrease perspiration w/o altering level of sedation. Technique for Oversedation.
77
are patients who have had sedation before more or less difficult to gauge proper level of sedation?
less difficult
in other words, it is harder to gauge for people who have never had sedation
78
what is an indication of your patient being near the ideal level of sedation?
patient's responses become slower, increase in lag time between questions and answers
79
The only way of determining with absolute accuracy whether the proper sedative level has been achieved is to \_\_\_.
begin the planned treatment and observe the patient’s response
## Footnote
* Not unusual for patient to make movements, especially when traumatic procedure, eg: LA. If this is disruptive & significant, stop & increase percentage N20 5%. Usually eliminates problem.
* Once pain control (LA) established, procedure usually proceeds with little difficulty.
80
A prime benefit of inhalation sedation is ability to \_\_\_.
tailor sedation to needs of the patient
81
As treatment proceeds & anxiety level decreases, patient may become overly sedated. what should you do in this case?
Decrease N20 flow 5% & within 30-60 seconds patient will become less sedated.
## Footnote
•Patient should be able to respond to questions posed. Lack of response indicates treatment to be terminated immediately & re-evaluate. Usually decreasing N20 5-10% quickly brings a response.
82
what should you do when treatment is completed?
* At completion of tx, terminate N20 flow and allow patient to breathe 100% O2 for at least 3-5 min. Longer period may be needed if long procedure or S & S of sedation persist.
* N20 is not “titrated” out of patient like it is at start of procedure.
* Proper time to turn off N20 varies. May be advantageous to terminate before tx ends. Can be done w/o patients awareness.
83
After N2O administration, the patient is discharged and allowed to resume normal activities without any prohibition. at this point, what is the responsibility of the dentist?
* the dentist must be absolutely certain that recovery is complete before considering discharge. Some will require an escort.
* The response to questioning is the primary determinant of recovery from sedation. Subjective response.
84
response to questioning as a primary determinant of sedation recovery is considered a subjective response. what are objective tests that can determine sedation recovery?
* Vital Signs
* Neurologic Test: Touching tip of nose with little finger, Trieger Test.
* Useful for medicolegal documentation.
85
describe cleansing of the nitrous oxide equipment after use
* Nasal hoods – have been shown to be contaminated with multiple human pathogens capable of transmission from one patient to another.
* Sterilization – After each use, wash w/ soap & warm water. Then immerse in glutaraldehyde solution for 10 minutes. Rinse w/ tap water.
* Tubing, Reservoir Bags & Nasal Hoods – each week stored for 10 hrs. in glutaraldehyde, then rinsed in warm tap water for 1 hr.
86
what are the signs and symptoms of oversedation?
* Persistantly closes mouth
* Spontaneously begins mouth breathing
* Complains of Nausea and effects of sedation felt as too intense or uncomfortable
* Fails to respond rationally or gives sluggish responses
* Begins to lose control
* Speaks incoherently or dreams
* Becomes uncooperative
* Laughs, Cries or becomes Giddy
* Uncoordinated Movements
87
what are the absolute contraindications of N2O administration?
* COPD
* Severe emotional disturbances or drug prob.
* First Trimester Pregnancy
* Cancer treatment with Bleomycin sulfate
* Pernicious Anemia or vitamin B12 deficiency
* Pneumothorax
* Cystic fibrosis
* Recent Pneumoencephalography
* Significant Bowel Obstruction
* Serious head/facial injuries
* Inability to understand procedure or unwilling to consent to procedure
