CHAPTER 8: PAIN REACTION CONTROL: SEDATION

book

General anesthesia

Totally eliminates anxiety.

Elevates the pain reaction threshold

Sedation

• Depending on its depth, produces a relative reduction in anxiety.

• Facilitates:

  1. An increased opportunity for the patient to use learned coping skills.

  2. A reduction in the reactions to painful stimuli.

Factors Affecting Degree of Sedation

• Drug factors

  • Dose

  • Route

  • Rate of administration

• Patient factors

  • Age

  • General health

  • Size

  • Metabolic rate

anxiolysis

the previous term refers to Minimal sedation

conscious sedation

the previous term refers to moderate sedation

Commission of Dental Accreditation (CODA)

Residency training beyond dental school that is formally accredited for those providing:

• Deep sedation

• General anesthesia

“Guidelines for the Elective Use of Conscious Sedation, Deep Sedation, and General Anesthesia in Pediatric Patients.”

jointly endorsed by American Academy of Pediatrics (AAP) and the American Academy of Pediatric Dentistry (AAPD) In 1985

• These guidelines set the current standard of care for those who practice these sedation techniques for pediatric patients.

• The most recent cosponsored guidelines using the definitions of:

  • Minimal sedation

  • Moderate sedation

  • Deep sedation

goals of sedation

1. Guard the patient’s safety and welfare.

2. Minimize physical discomfort and pain.

3. Control anxiety, minimize psychological trauma, and maximize the potential for amnesia.

4. Control behavior and/or movement, which allows the safe completion of the procedure.

5. Return the patient to a state in which safe discharge from medical supervision, as determined by recognized criteria, is possible.

goal of minimal and moderate sedation

• a level of sedation that:

  • Does not render the patient unconscious.

  • Does not render the patient unresponsive to verbal prompting.

  • At the most, does not render the patient unresponsive to minimally painful stimuli.

patient under minimal and moderate sedation

can respond appropriately to verbal commands or minimally noxious stimuli.

is able to maintain a patent airway at all times

• A reflex withdrawal response alone to repeated minimal or moderately painful stimuli:

  • Is not appropriate for minimal and moderate sedation.

  • Is indicative of deeper levels of sedation.

Minimal sedation

• a drug-induced state during which patients respond normally to verbal commands.

• Although cognitive function and coordination may be impaired:

  • Ventilatory functions are unaffected.

  • Cardiovascular functions are unaffected.

Moderate sedation

• a drug-induced depression of consciousness during which patients respond purposefully to verbal commands.

  • Example:

    • “Open your eyes”

  • Either alone or accompanied by light tactile stimulation:

    • A light tap on the shoulder or face

    • Not a sternal rub

• The caveat that loss of consciousness should be unlikely is a particularly important aspect of the definition of moderate sedation.

• The drugs and techniques used should carry a margin of safety wide enough to render unintended loss of consciousness highly unlikely.

Moderate Sedation Responses

• Moderate sedation suggests that a child may be in a state wherein eyes are temporarily closed.

• However, the child is arousable following:

  • A verbal prompt

    • Opens his or her eyes

  • Or responds to the degree that withdrawal and crying occur following mildly painful stimulus, such as an injection of local anesthetic.

• Withdrawal from painful stimuli and crying are prominent at this level of sedation.

• Deeper levels of sedation may result only in:

  • Reflex withdrawal

  • Reflex withdrawal and moaning

• If arousal, as described previously, does not occur:

  • Especially following a repeated moderately painful stimulus (e.g., trapezius muscle pinch)

  • Then the child is in a state of deep sedation and must be managed and monitored accordingly.

• Observation of chest movements and continuous verbal communication are acceptable for moderate sedation.

• However, because continuous verbal communication may be undesirable for the child patient:

  • A precordial stethoscope or capnography is usually required for moderate sedation.

  • A precordial stethoscope or capnography is always required for deep sedation.

• If the patient enters a deeper level of sedation than the dentist is qualified to provide:

  • The dentist must stop the dental procedure until the patient returns to the intended level of sedation.

minimal monitoring requirements for moderate sedation

• Pulse oximeter

  • For monitoring oxygenation and pulse rate

• Blood pressure cuff

  • For monitoring circulation

• Precordial stethoscope or capnography

  • To monitor ventilation

Deep sedation

• a controlled state of depressed consciousness or unconsciousness from which the patient is not easily aroused.

• Deep sedation may be accompanied by a partial or complete loss of protective reflexes, including:

  • The ability to maintain a patent airway independently.

  • The ability to respond purposefully to physical stimulation or verbal command.

• Young patients who are in deep sedation may respond with only a reflex withdrawal to an intensely painful stimulus, if at all.

Monitoring requirements for deep sedation

• Pulse oximeter

• Capnography or precordial stethoscope

• Electrocardiography

• Blood pressure cuff

General anesthesia

a controlled state of unconsciousness accompanied by a loss of protective reflexes, including:

• The inability to maintain an airway independently.

• The inability to respond purposefully to physical stimulation or verbal command.

Why Is Progression to Deep Sedation a Problem?

• The patient has a much more frequent and serious risk of respiratory or cardiovascular complications during deeper levels of sedation.

• When the patient has a partial or complete loss of protective reflexes and cannot maintain an airway independently:

  • Hypoxemia

  • Laryngospasm

  • Pulmonary aspiration

  • Apnea

• These may be serious or life-threatening outcomes.

• Because the separation between moderate and deep sedation can sometimes be difficult to discern:

  • It is the wise practitioner who obtains proper training in monitoring techniques and managing sedation before using pharmacologic management for children.

3 Standards That Changed Pediatric Sedation Practice

personnel

patient monitoring

preprocedural prescriptions

personnel

• The guidelines specify that:

  • An assistant other than the dental operator must participate in the sedation procedure.

  • This assistant must be trained to:

    • Monitor appropriate physiologic parameters.

    • Assist in any support or resuscitation measures required.

patient monitoring

• Relative to intraoperative monitoring procedures during sedation:

  • The guidelines specify continuous monitoring by a trained individual.

• A:

  • Precordial stethoscope

  • Blood pressure cuff

  • Pulse oximeter

• Are considered the minimal equipment needed for obtaining continuous information on:

  • Heart rate

  • Respiratory rate

preprocedural prescriptions

• refer to the practitioner giving a written prescription to the parent to obtain and administer the sedative agent(s) outside of the treatment facility.

• Drugs intended for sedation, particularly in a dose that has even a slight potential to make the child difficult to arouse or potentially lose consciousness:

  • Should never be administered at home by parents or guardians:

    • On the night before sedation.

    • During the day of sedation before transporting a child to a facility where a procedure will be performed.

    • ex: chloral hydrate, meperidine [Demerol], high-dose benzodiazepines

diazepam [Valium]

preprocedural prescriptions to relieve anxiety for older children who are extremely anxious may be helpful.

although no strong evidence is available to support this notion.

Chloral hydrate & meperidine

are not considered minor tranquilizers or antianxiety agents.

Thus, they should not be administered to a child outside of the dental office

primary routes of administration for minimal and moderate sedation

• Inhalational

• Enteral

  • E.g., oral or rectal

• Parenteral

  • E.g., intramuscular

  • Subcutaneous

  • Submucosal

  • Intranasal

  • Intravenous

advantages of inhalational Route (Nitrous Oxide)

Rapid Onset and Recovery Time

• Because nitrous oxide has very low blood:gas solubility:

  • It reaches a therapeutic level in the blood rapidly.

  • Conversely, blood levels decrease rapidly when nitrous oxide is discontinued.

Ease of Dose Control (Titration)

• There are two ways to initially administer nitrous oxide to children:

  1. The standard titration technique used on adults.

  2. The rapid “induction” technique

Nitrous Oxide Hygiene

• Good nitrous oxide hygiene is always indicated and includes:

  • The use of a scavenging system (see Fig. 8.3B)

  • Large operatories

  • Rapid room air exchanges

  • Supplemental movement of air:

    • I.e., fans

  • A nasal hood that adapts closely to the nose area of the face

Lack of Serious Adverse Effects

• Nitrous oxide is considered to be physiologically safe for the patient when administered with adequate oxygen.

• The most commonly encountered adverse effect is:

  • Nausea

• Nausea should be very rare unless high concentrations of nitrous oxide are used.

• Poor technique with high concentrations may also result in an “excitement phase” in which the patient may become:

  • Uncomfortable

  • Uncooperative

  • Delirious

• This resembles a transitional stage to general anesthesia

Standard Titration Technique of Nitrous Oxide

• Nitrous oxide should be started at 10% concentration.

• Increased in increments ranging from 5% to 10%, until:

  • The patient becomes comfortable.

  • Clinical signs of optimal sedation are noted.

• Signs of optimal sedation that may be observed include:

  • Slight relaxation of the limbs and jaw muscles

  • Ptosis of the eyelids

  • A blank stare as if looking up at a star-filled evening sky

  • Palms open, warm, and slightly moist

  • Slight change in the pitch of the patient’s voice

  • A lowered heart rate

  • Patient reports of being comfortable and relaxed

• Each time the clinician increases the concentration:

  • He or she should wait at least 30 to 60 seconds.

  • While talking with the child and watching for these signs of optimal sedation.

  • Before deciding to increase the concentration again.

• The end point in terms of maximal concentration of nitrous oxide usually should not exceed 50% for children.

• Most children seem comfortable and demonstrate optimal signs of sedation in the concentration range of 35% to 50% nitrous oxide (Fig. 8.3A).

• The standard titration technique is primarily used for:

  • Mildly to moderately anxious

  • Cooperative children

Rapid “Induction” Technique of Nitrous Oxide

• A second option to the standard titration technique of nitrous oxide administration is the rapid “induction” technique.

• This technique is usually indicated for:

  • The mild to moderately anxious

  • Potentially cooperative child

  • Who may be on the edge of losing coping abilities

  • And needs to be controlled quickly by the clinician.

• The technique involves:

  • Administering 50% nitrous oxide immediately to the patient without any titration steps.

When to Discontinue Nitrous Oxide

• In either technique, nitrous oxide should be discontinued if:

  • The child becomes disruptive.

  • The child no longer breathes through the nitrous oxide hood.

• Gas flow should also be terminated if:

  • The child becomes nauseated.

  • The child vomits.

  • Or both.

disadvantages of inhalational Route (Nitrous Oxide)

Weak Agent

• Attempts to increase the concentration of nitrous oxide to control moderately or severely anxious patients will be fraught with failure.

• It will not be pleasant for:

  • The operator

  • The patient

Lack of Patient Acceptance

• There are some patients:

  • Adults

  • Children

• Who do not find the effects of nitrous oxide pleasant.

• These patients may become overtly noncompliant:

  • Removing the nasal mask

  • Becoming otherwise uncooperative

Inconvenience

• In some areas, such as the maxillary anterior teeth:

  • The use of a nitrous oxide nasal mask may hinder exposure of the area.

• This may be a problem, especially in small children.

Contraindications of nitrous Oxide

• Acute otitis media (middle ear infection)

  • Is a primary contraindication to nitrous oxide/oxygen use in children.

  • Because it may enter the closed tympanic space and rupture the eardrum.

• Children with active pulmonary infection:

  • Are not good candidates for nitrous oxide.

  • But also are generally not seen in the dental office.

• A history of asthma:

  • Is not a contraindication to nitrous oxide.

• Older children with serious mental health concerns:

  • May respond inappropriately to the psychogenic effects of nitrous oxide.

  • Just as they may to other sedatives.

induction

commonly used to describe entrance into general anesthesia, which is almost impossible with fail-safe dental nitrous oxide delivery systems and is not meant to imply entrance into a state of general anesthesia as used in this chapter.

Potential Chronic Toxicity of nitrous Oxide

• Spontaneous abortions

• Congenital malformations

• Certain cancers

• Liver disease

• Kidney disease

• Neurologic disease

Nitrous oxide (N₂O)

• is relatively safe and effective for children in the dental office.

• Best for:

  • Minimal anxiety

  • Cooperative children who can follow instructions

• Poor candidates:

  • Children with nasal obstruction

  • Uncooperative children who cannot breathe through the nose

• Provides analgesia and raises pain threshold, but usually does not replace local anesthesia.

• Can help children with short attention spans by altering perception of the environment and passage of time.

gas flow of Nitrous oxide (N₂O)

• Adults: 5–7 L/min

• 3–4 years old: 3–5 L/min

• Begin with 100% oxygen for 3–5 minutes.

• Increase nitrous oxide to 30–35% for 3–5 minutes for induction.

• May increase to 50% for 3–5 minutes for maximum analgesia during local anesthetic injection.

• After injection:

  • Reduce to 30–35% for maintenance.

  • Or use 100% oxygen if N₂O is only needed for injection-related behavior management.

• After discontinuation:

  • Give 100% oxygen for at least 3–5 minutes to prevent diffusion hypoxia.

• Nitrous oxide should be an adjunct to behavioral management, not a substitute for it.

advantages of Oral Route

• Convenient and easy.

• Economical; no special administration equipment required.

• Extremely safe when therapeutic doses are properly calculated and single drugs/single doses are used.

• Commonly used for minimal and moderate sedation in pediatric dentistry.

disadvantages of Oral Route

• Variable effect: children of the same weight may respond differently.

• Absorption can be affected by food, anxiety, emotional state, fatigue, medications, and gastric emptying.

• Patient may refuse or vomit the medication.

• Paradoxical reactions may cause agitation and increased uncooperativeness.

• Titration is not possible or safe.

• A second dose should never be given to compensate for an apparently ineffective first dose because cumulative overdose may cause:

  • Respiratory arrest

  • Cardiovascular collapse

  • Death

• Longest onset time: approximately 15–90 minutes.

• Adequate dose and sufficient time for absorption are essential

advantages of Intranasal Route

• Occasionally used, especially in young children who cannot tolerate unpleasant-tasting oral medication.

• Medication is sprayed or dripped into the nostrils.

• Little to no cooperation required.

• Full calculated dose given with high certainty.

• Mucosal atomizer improves comfort and administration.

• Bypasses GI tract and hepatic metabolism.

• Faster onset than oral administration

disadvantages of Intranasal Route

• May cause burning and discomfort.

• Topical anesthetic may reduce discomfort but adds another intranasal drug.

• Drug effect cannot be titrated.

• Parenteral administration may increase liability costs and require permits.

advantages of Intramuscular Route

• Sedative is injected into a skeletal muscle.

• Faster and more dependable absorption than oral administration.

• Technically easy; requires only a syringe and needle.

• Little or no cooperation required.

• Full calculated dose can be administered with high certainty.

• Easier than IV catheter placement, even with restraint.

disadvantages of Intramuscular Route

• Absorption may be delayed by peripheral vasoconstriction.

• Absorption is unpredictable if the drug enters fat or between muscle layers.

• Drug effect cannot be safely titrated.

• Standard dose may have little effect in some children and heavily sedate others.

• Possible tissue trauma and hematoma.

• No IV access in case of emergency.

• Higher malpractice costs and possible permit requirements.

advantages of Subcutaneous Route

• Occasionally used for pediatric sedation.

• Usually involves injection into an intraoral submucosal space, commonly the buccal vestibule.

• Submucosal oral injections may be more acceptable to some patients and parents.

• More comfortable and convenient for the dentist.

disadvantages of Subcutaneous Route

• Slower absorption than other parenteral routes.

• Subcutaneous tissue has relatively sparse blood supply.

• Oral submucosal injections have relatively rapid effects because of abundant vascularity.

• Risk of tissue sloughing.

• Only nonirritating substances should be used.

• Large volumes should not be injected.

• Increased malpractice costs and possible permit requirements.

advantages of Intravenous Route

• Only parenteral route allowing exact titration.

• Drug directly enters bloodstream, so absorption is not a factor.

• Consistent time to peak effect.

• Small incremental doses can achieve the desired sedation level.

• Avoids underdosing or overdosing associated with standardized single doses.

• Allows a small test dose to assess allergic reaction or sensitivity.

• Provides immediate IV access for emergency drugs.

• Considered the optimal and ideal route for sedative agents.

disadvantages of Intravenous Route

• Technically the most difficult route.

• Requires training, extensive practice, and patient cooperation.

• IV catheter placement can be particularly difficult in young children.

• Greater potential for complications because drugs enter directly into the bloodstream:

  • Extravasation

  • Hematoma

  • Intraarterial injection

  • Exaggerated effects from rapid injection

  • Rapid, potentially life-threatening anaphylactic reaction

  • Thrombophlebitis

• Requires higher levels of patient monitoring.

• Higher liability costs.

• Additional monitoring and equipment make IV sedation costly.

3 primary groups of drugs are used for sedation in pediatric

sedative-hypnotics

anti-anxiety agents

narcotic analgesics

sedative-hypnotics

• Principal effect:

  • Sedation or sleepiness.

• As the dose is increased:

  • Patient becomes increasingly drowsy.

  • Sleep (hypnosis) is produced.

  • Further increasing the dose can produce:

    • General anesthesia

    • Coma

    • Death

• The primary effect of these drugs is not:

  • To decrease anxiety.

  • To raise the pain threshold (analgesia).

• A sedative-hypnotic used alone may actually lower the pain reaction threshold in some cases by removing inhibitions.

• At inadequate dosages:

  • It may simply produce a patient who is more responsive to pain stimulation.

• Principal action:

  • Initial primary effect on the reticular activating system, an area of the brain involved in maintaining consciousness.

  • Further increases in dose will affect other brain areas, especially the cortex.

Categories of Sedative-Hypnotics

• Barbiturates

  • Pentobarbital

  • Secobarbital

  • Methohexital

• Benzodiazepines

  • Discussed in the antianxiety section

• Nonbarbiturates

  • Chloral hydrate

  • Paraldehyde

anti-anxiety agents

narcotic analgesics

Oral chloral hydrate

• Low doses: 15–25 mg/kg

  • Maximum: 1000 mg

  • Can produce:

    • Minimal sedation

    • Moderate sedation

  • Or it can have the opposite effect:

    • Producing a resistive and agitated patient

    • As occurs also with barbiturate sedation in children.

• Higher doses: 30–50 mg/kg

  • Especially in combination with other medications such as:

    • Hydroxyzine (Atarax or Vistaril)

    • Meperidine

  • Can produce deeper levels of sedation.

• Due to the increased risk of:

  • Respiratory depression

  • Loss of consciousness

• Patients’ vital signs and level of consciousness must be monitored closely.

• Chloral hydrate is bitter tasting:

  • Can produce management problems during administration.

• A final disadvantage:

  • Chloral hydrate can induce nausea and vomiting secondary to gastric irritability.

Pentobarbital

• The most commonly used oral barbiturate for pediatric sedation is pentobarbital.

• Commonly used by pediatric medical radiologists.

• Has not found much favor with pediatric dentists.

Antianxiety Agents

• Primary effect:

  • Removing or decreasing anxiety.

• Primary site of action:

  • Limbic system

  • The “seat of the emotions.”

• Theoretically, a dose exists for each antianxiety agent at which:

  • Anxiety will be decreased.

  • Without producing significant sedation.

• However, as doses are increased:

  • The reticular activating system and then the cortex are affected.

  • Producing sedation as well as sleep.

• Thus, some benzodiazepines are also classified as sedative-hypnotics.

• Because anxiety is often the primary problem in people with dental phobias:

  • A primary effect against anxiety appears to be desirable.

  • Especially in reasonably cooperative adults.

• Antianxiety drugs possess a flatter dose-response curve, pharmacologically, than many of the sedative-hypnotics:

  • Especially barbiturates.

• This allows for a safer therapeutic index.

• This means that for most antianxiety drugs:

  • E.g., diazepam

  • A larger difference exists between the dose that will produce loss of consciousness than is the case with a rapidly acting sedative-hypnotic.

  • E.g., methohexital [Brevital]

• Methohexital has a steep dose-response curve:

  • The difference between a minimally sedating dose and a general anesthetic dose is smaller.

• Drugs such as methohexital should not be used for sedation for this reason.

• Antianxiety agents produce no analgesia.

Benzodiazepines

• Antianxiety agents consist primarily of the benzodiazepines, such as:

  • Diazepam

  • Midazolam (Versed)

  • Triazolam (Halcion)

• This group of agents is the one principally used for minimal and moderate sedation in adults.

Midazolam:

Is the only agent that has been extensively studied in children.

Is the most frequently used agent for pediatric oral sedation in medicine and dentistry.

• Positive characteristics of midazolam:

  • Rapid onset

  • Decreased likelihood of inducing loss of consciousness

• Characteristics that are not always beneficial to the practitioner for some operative procedures:

  • Short duration of action

  • Potential increased patient irritability primarily after dental local anesthetic administration.

Flumazenil

• a benzodiazepine antagonist.

• Can reverse the effects of:

  • Benzodiazepine-related sedation

  • Overdose

• As with many reversal agents:

  • The practitioner must be aware that the duration of action of a reversal agent may not last as long as the effects mediated by the drug being reversed.

• Consequently:

  • The reversal agent may have to be given parenterally in repeated doses.

antihistamines

• Some antihistamines possess both:

  • Antianxiety properties

  • Sedative-hypnotic properties

• Examples:

  • Hydroxyzine

  • Diphenhydramine (Benadryl)

• They are often classified with the antianxiety agents.

• These drugs are not very useful for sedation when used alone.

• They are useful in combination with other drugs, such as:

  • Chloral hydrate

  • Meperidine

• They are used:

  • As potentiating agents.

  • For their antiemetic properties.

Opioids

• are commonly referred to as narcotics.

• These drugs are also used in sedation for their primary action of:

  • Analgesia

• Site of action:

  • Opioid receptors of the CNS.

• These drugs modify the interpretation of the pain stimulus in the CNS.

• Therefore:

  • Raise the pain threshold.

• As the dose of the narcotic is increased:

  • Other effects such as sedation will occur.

• Sedation per se is not the principal end point sought from a narcotic.

• If narcotic dosage is increased to achieve sedation:

  • Serious adverse effects will be encountered.

• Most common adverse effects:

  • Respiratory depression

  • Apnea

• These can lead to:

  • Hypoxia

  • Death

• If sedation is desired:

  • The narcotic should be considered an adjunct to a drug that produces sedation as its primary effect.

Other Effects of Narcotics

• Narcotics may produce:

  • Nausea

  • Vomiting

• Especially when used alone.

• In high doses:

  • Narcotics may also induce cardiovascular depression.

• Narcotics strongly potentiate other CNS depressant drugs.

• Therefore, the principal use of narcotics in minimal and moderate sedation should be:

  • To augment the effects of the sedative-hypnotic or antianxiety agents.

  • To contribute some degree of analgesia that other agents do not provide.

• The analgesia obtained with narcotics:

  • Cannot be used as a substitute for adequate local anesthesia.

• Narcotics cause supraadditive respiratory depression when combined with sedative-hypnotics or antianxiety agents.

• This means:The respiratory depressant effect of the combination of agents is much greater than the additive respiratory depressant effects that would be expected.

Meperidine

• The narcotic most commonly used in pediatric sedation techniques is meperidine.

• When considering the use of narcotics in pediatric dentistry:

  • It is wise to remember the definition of...

• To reiterate:

  • The caveats that loss of consciousness should never occur in moderate sedation or be unlikely in moderate sedation are particularly important parts of the definitions of these sedative levels.

  • For moderate sedation, the drugs and techniques used should carry a margin of safety wide enough to render unintentional loss of consciousness unlikely.

• Narcotics have steep dose-response curves.

• They must be used with extreme caution for minimal and moderate sedation because they carry a high risk of:

  • Respiratory depression

  • Loss of consciousness

• Especially if they are combined with other agents such as:

  • Nitrous oxide

Naloxone

• Naloxone is an opioid antagonist.

• Can be administered parenterally to reverse the adverse effects of opioid-related sedation:

  • E.g., respiratory depression.

Ketamine

• The dissociative agent ketamine has had periods of popularity in pediatric dental practice.

• It produces:

  • A cataleptic state

  • Profound analgesia

  • Varying amnesia depending on dose

• Ketamine acts primarily on:

  • Thalamus

  • Cortex

• It does not primarily act on the reticular activating system.

• Therefore:

  • The patient does not appear to be asleep.

  • Rather, the patient is dissociated from the environment.

• Respirations usually are not depressed with proper dosages.

• Stimulatory cardiovascular changes usually are produced.

• Therefore:

  • Tachycardia can be expected.

  • Increased blood pressure can be expected.

• Other common effects:

  • Nystagmus

  • Increased salivation

• Ketamine is mentioned primarily to point out that it is classified as a general anesthetic because:

  • The patient under its influence is incapable of making appropriate responses to verbal commands or stimulation.

• It may cause:

  • Respiratory depression

  • Respiratory arrest

  • Delirium

  • Hallucinations

• Ketamine should be used only by practitioners qualified to administer general anesthesia.

Pulse Oximeter

• A pulse oximeter is a self-contained instrument that noninvasively monitors:

  • The degree of oxygen saturation of the patient’s hemoglobin.

  • The patient’s pulse rate.

• Oxygen sensors placed across perfused tissue beds in which a pulse can be detected:

  • E.g., the fingertip

• Determine oxygen saturation by measuring differences in the absorption of:

  • Red light

  • Infrared light

• These are emitted by the sensors.

• Normally, the hemoglobin in arteries of healthy children and adults is:

  • 97% to 99% saturated

  • But is frequently read as 100% by pulse oximeters.

• The pulse oximeter is generally quite accurate.

• However, some factors may cause “false alarms” that incorrectly indicate low oxygen levels:

  • Patient movement artifacts

  • Cold tissue beds

  • Poor perfusion of tissue beds

  • Crying

Precordial Stethoscope

• A precordial stethoscope is essentially a stethoscope whose bell is temporarily attached to the chest wall.

• It is used for monitoring:

  • Ventilation (Fig. 8.6A and B)

• By listening through the stethoscope, the clinician can determine:

  • Respiratory rate

  • Quality of air movement during breathing

  • Heart sounds

• The closer the bell of the stethoscope is placed to the precordial notch:

  • I.e., in the soft tissue area immediately above the manubrium of the chest

  • The louder are the breathing sounds in comparison with the heart sounds.

• Partially occluded airways or restrictive airways have different sound qualities, including:

  • Wheezing

  • Stridor

  • Crowing

• The precordial stethoscope is especially sensitive to competing operatory sounds:

  • E.g., the pitch of the high-speed handpiece

• The operator must rely frequently on:

  • Other clinical signs:

    • E.g., chest excursions

  • Physiologic monitors:

    • E.g., capnographs (Fig. 8.7)

• To determine the stability and condition of the patient.