Chapter 12: Inhalation Sedation - Rationale Flashcards
What can you not predict about sedation? What must you be able to do during sedation?
Can’t predict how a patient will respond. Therefore practitioners intending to give a certain level of sedation should be able to rescue a deeper level of sedation than was intended
What are some noninvasive, non-pharmacologic approaches to sedation?
- Iatrosedation
- Hypnosis
- Acupuncture and acupressure
- Systemic desensitization
- Relaxation therapy
- TENS and EDA
Conscious Sedation
LA, Oral, IM, IH, IV
Oral sedation
Patient cooperation necessary, latent period, prolonged duration and recovery; no titration
Intramuscular
more rapid onset, more reliable, prolonged duration and recovery, no titration; injection necessary
Inhalation
Many advantages few disadvantages, rapid, titration possible; elimination is rapid
Intravenous
Rapid response and onset; titratable
Desirable characteristics of N2O
- Analgesic
- Anxiolytic
- Amnesic
- Rapid onset of action
- Titration possible
- Rapid and complete recovery
Analgesic Quiz Q’s
___% N2O is equivalent to 15mg Morphine
Who is N2O useful in? What can N2O do to pain threshold? What is it particularly benefical during?
20% N2O is equivalent to 15 mg Morphine
Useful in patients having pain from MI
Increased pain threshold prior to injection of local anesthetic
Anxiolytic - helps with? What does it do in pediatric patients?
Helps with fear and anxiety creating a sense of well-being. In pediatric patients, N2O facilitates positive behavior and decreased anxiety on sequential visits
What are the effects of of amnesia?
Cannot recall the severity of pain or duration
Passage of time is unclear
Nedley’s Notes: Memory restructuring is a behavior guidance technique – he doesn’t know if he’s fully embraced it
Everyone tolerates things differently
Give them a NON-verbal clue that you’re done – once you’re done GET AWAY. When you’re done be done. Take your gloves and walk away
Your non-verbal communication is more important than what you’re saying
What is the onset of action of N2O? and when do the peak effects of N2O occur?
Less than 30 sec and peak effects occurring in less than 5 min
Define titration
Process of administering a drug incrementally to a specific level or endpoint
Rapid and complete recovery from N2O - how do you achieve this in pediatric patients? Is it variable or not - why?
100% O2 for 5 min; Recovery is variable especially if patient is not breathing nasally
Nedley’s Notes: Kids might be a little “doppy” after
Sit them up a little bit at a time and keep them on oxygen until they’re ready to go
Combining N2O/O2 with other sedation methods
Used safely with oral sedation (diazepam, meperidine)
Not a replacement for local anesthesia
Define pharmacokinetics
Pharmacokinetics of a drug affect uptake, distribution, metabolism and elimination; movement of drug, where it goes, uptake, distribution, metabolism, and elimination
Define pharmacodynamics
Pharmacodynamics: what the drug does to the body
What happens to the gases in inhalation sedation?
Inhaled gases move across partial pressure gradients
Pharmacokinetics of N2O
Low blood-gas partition coefficient of .47
Insoluble
Rapid onset of action
Peak clinical effect in 3-5 minutes
What is the 2nd gas effect?
At high concentrations of N2O volume of inspired gas is increased; Rapid uptake of N2O allows a 2nd gas to be introduced faster than it would alone…watch in OR
Nedley’s notes: With adults, IV induction
N2O taken in quickly – creates vortex that takes in 2nd gas faster
Elimination of N2O
99% of N2O eliminated through the lungs unchanged
.004% metabolized in the gastrointestinal tract
True or False: The onset of action of inhalation sedation is the most rapid of all sedation techniques
True: it is more rapid than that of oral, rectal, intranasal (IN), or intramuscular (IM) sedation
True or False: The onset of action of IV medications is approximately, but not quite, equal to that of inhalation sedation.
True
Onset time for inhalation
<20 second pulmonary circulation to brain time; 2-3 minute onset for clinical actions to develop
True or False: Peak clinical effect does not develop in most techniques for a considerable time
true
Which types of inhalation provide peak clinical actions in a time span permitting titration?
Inhalation and IV
IV route onset time and peak effect
20-sec onset time (approximate arm-to-brain circulation time); 1-2 minutes for clinical actions to develop. For the IV route, this time-to-peak-effect varies with the drug administered, ranging from 1 minute to approximately 20 minutes (e.g. lorazepam)
Peak action time for inhalation
3-5 minutes peak action time
peak action time for IV
60 seconds to 20 minutes peak action
Inhalation Depth of Sedation
sedation levels easily changed either way
Duration of action
duration variable, at discretion of administrator
Recovery from inhalation sedation
It’s rapid and the most complete of any pharmacosedation technique. N2O is not metabolized by the body, the gas is rapidly and virtually completely eliminated from the body within 3-5 minutes
Recovery time from inhalation sedation
recovery usually complete after 3-5 minutes of inhalation of 100% O2
Greatest safety feature of N2O
being able to titrate a drug because it permits the drug administrator virtually absolute control over the actions of the drug
In which kind of drugs is titration possible?
IV and Inhalation
No adverse effects from N2O are present on which systems?
liver, kidneys, brain, or cardiovascular and respiratory systems
The analgesia produced by a ___% concentration of N2O is equivalent to 10-15mg of morphine
50%
Disadvantages of N2O
1) initial cost of the equipment
2) continuing cost of the gases
3) equipment required for inhalation sedation occupies considerable space
4) N2O is not a potent agent
5) A degree of cooperation from the patient is required
6) all members of the sedation team employing N2O-O2 must receive training in its safe and effective use
7) there is a possibility that unscavenged trace nitrous oxide can be deleterious
primary indications for use of inhalation sedation are the same as those for other sedative techniques:
1) management of fear and anxiety
2) medically compromised patient
3) management of gagging
Name a respiratory disease that is relatively contraindicated in the use of N2O
COPD; the primary concern with patients with significant respiratory disease is the potential lack of sedative effect of the N2O-O2
Asthma and N2O
occasionally you’ll receive a medical consultation stating that the use of N2O-O2 is contraindicated in asthmatic patients. this is because anesthetic gases that are irritating to the respiratory mucosa may precipitate an acute episode of bronchospasm in patients with hyperactive airway disease (e.g. asthmatics). HOWEVER N2O is a nonirritating vapor that does not exacerbate asthma. the use of sedation in the asthmatic patient is frequently warranted because increased stress is a potential cause of acute exacerbation of asthma.
Respiratory diseases or conditions that will affect N2O/O2 inhalation
COPD, asthmatic patients, chronic nasal obstruction, either from anatomic abnormalities (deviated nasal septum) or pathologic conditions (allergy, upper respiratory tract infection), will be difficult to sedate adequately with gaseous agents
Cerebrovascular Disease
a patient who has had a cerebrovascular accident (CVA, “stroke”, “brain attack”) is unable to tolerate levels of O2 below normal without an increased risk of developing seizure activity or additional neuronal damage. Deep sedation is CONTRAindicated because of the increased (although unlikely) possibility of hypoxia. One of the most HIGHLY recommended for the patient who has had a CVA is N2O-O2 inhalation sedation. the major recommendation for this technique is the elevated level of O2 that is routinely provided to the patient. there is little or no likelihood of a hypoxic episode developing
Epilepsy and Seizure disorder
N2O is not epileptogenic (it does not increase the risk of seizures developing) and therefore may be administered to these patients as long as hypoxia is prevented. increased stress and anxiety have been demonstrated to be precipitating causes of seizures. Epilepsy does not represent a contraindication to the use of inhalation sedation.
Pregnancy
N2O does cross the placenta to the fetus, producing the same degree of CNS depression as in the mother. If delivered in combination with adequate levels of O2 (greater than 20%), N2O-O2 inhalation sedation represents the recommended sedation technique for use during pregnancy. Medical consultation with the patient’s physician before its use is suggested.
Suggestions for patients who gag
Use N2O-O2, it’s highly effective in eliminating or minimizing severe gagging; place the patient in an upright position for some or all of the procedure. N2O is practical to use for extremely short procedures, such as radiographs or impressions
Relative contraindications to N2O-O2 inhalation sedation
- patients with a compulsive personality
- claustrophobic patients
- children with severe behavior problems
- patients with severe personality disorders
- upper respiratory tract infection or other acute respiratory conditions
- chronic obstructive pulmonary disease
- the patient who does not want N2O-O2
- pregnancy
patients with severe personality disorders
patients who are under psychiatric care and are receiving psychotropic drugs, usually mood-elevating antidepressants, should be evaluated carefully before the administration of any form of sedation. although no serious drug-drug interactions develop between N2O-O2 and these psychotropic drugs, it may be prudent to avoid altering the consciousness of persons who have but a tenuous grip on reality. medical consultation before the use of any sedative technique is strongly indicated
avoid inhalation sedation in these situations…
common cold, acute or chronic sinus problems, chronic mouth breathing, allergy, tuberculosis, and bronchitis
COPD patients
COPD (e.g., emphysema, chronic bronchitis) represents a relative contraindication to inhalation sedation becuase of the potential effect of administering a gas mixture enriched with O2 to these patients, many of whom have chronically elevated CO2 blood levels. the stimulus for breathing in these patients is a lowered blood O2 content. during N2O-O2 use, the O2 saturation of blood is raised, therefore removing the stimulus for involuntary breathing…the patient should be watched for apnea. most of these patients represent ASA 3 and 4 risks during dental treatment.
first trimester and N2O
avoid the use of any drugs (if possible) during the first trimester to prevent increasing the slight risk for spontaneous abortion of the development of a fetal malformation that might be related to a drug administered at this time.
second trimester and N2O
drugs may be employed if necessary, but always use caution, especially with CNS depressants, and only after consultation with the patient’s primary care physician or OB-GYN.
third trimester and N2O
as the patient nears term, it might be prudent to postpone any nonemergency treatment. however, provide emergency care if needed if the patient requires sedation, the use of inhalation sedation is suggested. it is advised to consult with the patient’s obstretrician first.
Malamed’s thoughts on N2O
- it’s not metabolized in the body and has virtually no effect on most organ systems
- it is rapidly and almost entirely removed from the body within 3-5 minutes
- these facts provide ample evidence of its superiority over other techniques
