MONITORING DURING INTRAVENOUS SEDATION

Whenever drugs are administered parenterally, it is of paramount importance that the patient be monitored closely. Guidelines for monitoring during moderate sedation have been developed.^1–7 Every dentist must adhere to those regulations regarding monitoring that have been established by the dental governing body in the state or province in which they are licensed to practice.

The following represents this author’s recommendation for monitoring during IV moderate sedation:

The following monitoring devices are available (see discussion in Chapter 5):

The pretracheal stethoscope is recommended for use during IV moderate sedation procedures. It is both effective and inexpensive. The pulse oximeter has become a standard monitoring device during IV moderate sedation. Functioning as a continuous monitor of arterial oxygen (O₂) saturation and heart rate, the pulse oximeter represents the standard of care for monitoring during parenteral sedation. As an aside, recent graduates from U.S. dental schools who use IV moderate sedation would not even consider starting an IV sedation case in the absence of an oximeter.⁸ End-tidal CO₂ monitors (capnographs) are rapidly gaining entry into the monitoring armamentarium of dentists using general anesthesia or IV deep sedation and somewhat more gradually for IV moderate sedation. The ECG is less essential during parenteral sedation procedures than are techniques for monitoring the respiratory system. The ECG, though desirable, should be considered an optional monitor for IV moderate sedation. Regulatory bodies in a number of states have mandated the use of an ECG during IV moderate sedation.

The most important monitor used during IV moderate sedation is that for the central nervous system (CNS) through direct verbal contact with, and the response of, the patient. By definition (of moderate sedation), patients should be able to respond appropriately to verbal or physical stimulation throughout parenteral moderate sedation procedures.

BASIC INTRAVENOUS MODERATE SEDATION TECHNIQUES

These sedation techniques form the backbone of IV moderate sedation. Knowledge of these techniques will enable the trained dentist to meet the needs of a dental or surgical procedure of any duration, achieving satisfactory sedation for virtually all patients requiring IV moderate sedation (Box 26-1).

The Jorgensen technique is, arguably, the original IV moderate sedation technique.⁹ Despite efforts at modifying (e.g., improving) it, the original Jorgensen technique is still used, providing excellent sedation with few reports of any significant complications. The primary indication for the Jorgensen technique is a dental procedure requiring 2 or more hours to complete. Since the introduction of the benzodiazepines, especially midazolam, and because of the inability to reverse the clinical actions of pentobarbital, use of the Jorgensen technique has decreased. For an in-depth discussion of the Jorgensen technique, the reader is referred to earlier editions of this textbook.¹⁰ The Jorgensen technique is discussed later in this chapter.

IV moderate sedation using a benzodiazepine has replaced the Jorgensen technique as the most popular technique in dentistry.¹¹ IV benzodiazepine sedation meets the needs of contemporary dental practice (i.e., sedation for approximately 1 hour). Midazolam, introduced in the United States in 1985, has supplanted diazepam to become the most used IV technique in the area of 1-hour IV moderate sedation.¹¹

With the availability of these drugs, virtually all patients requiring IV moderate sedation will be successfully treated regardless of the length of the procedure.

Intravenous Benzodiazepine (Midazolam or Diazepam)

Preliminary Appointment

When either midazolam or diazepam is considered for use, specific questions must be asked of the patient regarding any prior exposure to the drugs and how they reacted to them. Specific contraindications to their use must be addressed. For midazolam and diazepam, these include the following:

1. Allergy or hypersensitivity to benzodiazepines

2. Glaucoma (untreated)

3. History of phlebitis, thrombophlebitis (contraindication to diazepam)

4. Acute pulmonary insufficiency (contraindication to midazolam)

5. Preexisting respiratory depression

Patients classified as American Society of Anesthesiologists (ASA) 1 and 2 are candidates for IV moderate sedation. ASA 3 patients might be considered, but only on a case-by-case basis.

Before the day of treatment, the following items concerning the patient’s suitability for IV moderate sedation are evaluated by the dentist and staff.

Degree of Apprehension

Which route of sedation (oral, intramuscular [IM], inhalation, IV) is most appropriate for this patient? If the IV route is selected, which technique is most appropriate for this patient?

Informed Consent

If the IV route is selected, informed consent must be provided to the patient, describing the IV procedure, its alternatives (e.g., IM, general anesthesia), and the most likely complications associated with its use. The patient signs the consent form, which is then added to the patient’s dental record. A specific informed consent for IV sedation should be signed before each IV procedure when multiple IV sedation visits are planned.¹³

Medical History

The medical history questionnaire, dialog history, and vital signs are reviewed seeking the presence of contraindications, either relative or absolute, to the use of the drugs considered.

Nature and Length of Dental Procedure Contemplated

The degree of trauma associated with the planned procedure must be considered in evaluating a potential sedative technique. In addition, the length of the procedure is also a consideration. Selection of appropriate drugs can tailor the length of sedation to almost any duration.

Presence of Superficial Veins

The presence of suitable superficial veins is a primary requisite for elective IV procedures. Lack of “good” (visible) veins is an acceptable reason for avoiding the IV route and selecting an alternative route of drug administration.

Recording of Baseline Vital Signs

Baseline vital signs are obtained at this visit if they have not been previously recorded.

Preoperative Instructions

The following is an example of preoperative instructions for IV moderate sedation:

1. Arrangements must be made for a responsible adult to drive the patient home after the IV moderate sedation appointment. The patient will be unable to leave the office alone.

COMMENT: A “responsible adult” may be defined as “a person who has a vested interest in the health and safety of the patient.” When the patient arrives for treatment, the name, address, and telephone number of his or her escort should be obtained immediately. If treatment is planned to last up to 1 hour, the escort is requested to accompany the patient to the office and remain during the procedure. For procedures lasting more than 2 hours, the escort is still requested to accompany the patient to the office. However, the dentist may elect to permit the escort to leave the office for the duration of the procedure and to return before the procedure is scheduled to end. In either case, it is extremely important to have seen or at least spoken to the patient’s escort before the start of the procedure. It is my policy to cancel the planned procedure whenever a suitable escort is not available at the start of treatment.

When oral sedation is prescribed preoperatively, an escort must drive the patient to the office.

2. The patient should have had nothing to eat for approximately 4 hours before the procedure.

COMMENT: The attempt here is to provide an empty stomach and gastric fluids with a higher pH in the highly unlikely event that the patient should become nauseous and vomit during or following the IV procedure. There is less likelihood of aspiration of solid or particulate matter if food is not present in the stomach. Patients may be permitted to ingest clear liquids, such as water or apple juice, along with any medications they may be required to take (e.g., antihypertensives). If the scheduled appointment is before noon, the patient is told not to eat anything that morning. For an afternoon IV sedation, the patient is advised to avoid anything by mouth after 8 am. A light, carbohydrate-rich breakfast consisting of dry cereal and juice may be taken before 8 am that morning. Medications may be taken normally, with water.

3. The patient is advised to wear loose-fitting garments.

COMMENT: This will minimize any possibly excessive respiratory depression caused by mechanical means. The upper garment worn by the patient should be of short-sleeved length or have no sleeves so that access may readily be gained to both arms.

Many dentists using IV moderate or deep sedation or general anesthesia have the patient change into a surgical shirt (or “scrubs”). Loose fitting and sleeveless, this permits the anesthesia team immediate and unimpeded access to the patient’s chest and upper body throughout the procedure.

4. The patient should plan to arrive at the office approximately 15 minutes before the scheduled appointment.

5. Should the patient develop a cold, flu, sore throat, or any other illness, the appointment will be canceled and rescheduled at a time when the patient is more physically fit. The patient should call if any of these symptoms develop.

COMMENT: Research has demonstrated that morbidity and mortality following anesthesia in patients with upper respiratory infections (URIs) are significantly greater in the time following the patient’s apparent “recovery” from the URI.¹⁴ Most of this morbidity is related to respiratory disease.

6. The medications to be taken before arrival in the office for treatment are prescribed, and the names of drugs, dosages, and instructions are given.

7. The time, date, and place of appointment are given to the patient.

Day of Treatment

The day of the scheduled dental treatment arrives, and the dentalphobic patient is in the waiting room. Knowing that the patient is fearful of the upcoming procedures, the dentist will not wish to prolong his or her wait any longer than necessary because the patient’s anxiety and fears will increase during this time.

An exception to this will be the patient receiving oral sedation before IV sedation. If the oral drug is not to be taken at home, the patient will be scheduled to arrive in the office approximately 1 hour before the scheduled start of the IV procedure, the oral sedative administered, and the patient asked to remain in the reception area.

During this time, the assistant will prepare the IV infusion and drugs for use (see Chapter 24). Once all is ready, the patient is asked to visit restroom to void, if necessary, following which the patient is taken to the treatment room and seated in a semiupright (comfortable) position. The availability of the patient’s escort should be determined at this time.

Once the patient is seated in the dental chair, monitors are placed, and preoperative vital signs are monitored and recorded on the anesthesia record sheet (Figure 26-1). Ideally the blood pressure cuff is placed on the arm opposite the working side of the dentist, remaining in place throughout the procedure. If used, the pretracheal stethoscope and ECG electrodes are applied along with the pulse oximeter or end-tidal CO₂ monitor. A nasal cannula or nasal hood is positioned, and a 3- to 6-L/min flow of O₂ is administered throughout the IV procedure.

Figure 26-1 Preoperative vital signs are recorded and entered onto the patient’s chart.

Because of an increased risk of phlebitis when diazepam is administered, it is suggested that, when possible, smaller veins, such as those on the dorsum of the hand or wrist, be avoided when venipuncture is performed.^15,16 This is not necessary with midazolam. Because midazolam is water soluble, phlebitis is uncommon, and venipuncture may be established at any available site, including the dorsum of the hand and wrist. Venipuncture is completed, and the IV infusion is established and secured (see Chapter 24).

Midazolam

Midazolam may now be administered to the patient. The midazolam has previously been readied for use by the dental assistant. This is now reviewed.

Midazolam is commonly administered intravenously in a concentration of 1 mg/ml. When the 5 mg/ml formulation of midazolam is used, 1 ml of the drug is placed into a 5-ml syringe and 4 ml of D₅W or 0.9% sodium chloride added. This provides a final concentration of 1 mg/ml midazolam. The syringe is recapped and labeled “midazolam 1 mg/ml.” Syringes containing drugs should always be labeled, even when only one drug is to be administered.

Drug Administration

The patient is placed in a supine position before drug administration. It is good practice to open up the IV infusion so that the rate of flow is rapid during the administration of any drug. This further dilutes the drug, minimizing any local irritation that might develop when the drug comes into contact with the vein wall.

Immediately before beginning drug administration, the assistant or dentist should make one final check to confirm that the IV infusion is still patent. By squeezing the flash bulb of the tubing or holding the bag of IV solution below the level of the patient’s heart, a return of blood into the tubing should be noted, a sign of a still patent IV line (Figure 26-2).

Figure 26-2 Holding bag of IV solution below level of vein should produce a return of blood into the tubing, a sign of a still patent IV.

A test dose of 0.2 ml (each small delineation on the 3-ml or 5-ml syringe is 0.2 ml) is administered to determine whether any unusual response (e.g., hypersensitivity, allergy) is to develop (Figure 26-3).

Figure 26-3 A, Needle inserted into injection port (arrow). B, C, Needleless syringe system.[]

After waiting about 20 seconds, titration of midazolam starts. The recommended rate of injection of midazolam is 1 ml/min, the equivalent of 1 mg of midazolam per minute.

The dentist should start by administering 0.5 ml slowly and continuously over 30 seconds. Because of the great individual variation in drug response, the dentist must always titrate carefully to each patient’s desirable level of sedation. Midazolam titration should continue at a rate of 1 ml/min until this ideal level of sedation is achieved.

When first learning to use IV moderate sedation, a dentist’s natural tendency will be to cease titration of midazolam at the very first sign of any change in the patient’s level of consciousness. Because of the uncertainty of the dentist, many patients may be undersedated. As clinical experience is gained, the dentist will develop a “feel” for the proper level of moderate sedation.

The following are clinical signs and symptoms associated with the desired level of moderate sedation:

• The patient will appear to become more relaxed in the dental chair in contrast to his or her earlier, more visibly tense demeanor. The patient may stretch out, uncross his or her legs, and relax his or her grip on the arm of the chair.

• The patient’s response to questions will be somewhat slower than it was earlier, and the patient may appear to have some difficulty in putting thoughts together into words.

• The patient may appear to be having difficulty keeping his or her eyelids open (as occurs when we are tired and begin to doze off). This is not to be considered the primary criterion for proper sedation. Halfway ptosis of the upper eyelid, the Verrill sign (Figure 26-4), usually occurs when the patient is somewhat overly sedated.^15,16

Figure 26-4 Halfway ptosis of the upper eyelid is often seen when diazepam is employed as an IV sedative.

When midazolam is administered at the recommended rate, the typical (normoresponding) patient in the middle of the “bell-shaped” curve requiring approximately 4 to 8 mg of midazolam will be sedated within 4 to 8 minutes of the start of drug administration. Once the desired level of sedation is reached, the rate of the IV infusion is slowed. Whenever a drug is not being administered, the infusion rate is adjusted to approximately 1 drop every 5 to 10 seconds. The purpose is to prevent a blood clot from forming in the needle during the procedure. This slow drip rate is commonly abbreviated as t.k.o. (to keep open).

Immediately after the administration of midazolam, vital signs and the drug dose (in milligrams) are recorded on the anesthesia record. Vital signs should be recorded immediately after any subsequent IV drug administration and at 5- to 10-minute intervals throughout the procedure. All drugs administered during IV moderate sedation, including local anesthetics, must be recorded on the anesthesia record.

Dosage

The average dose of midazolam required for clinically adequate IV moderate sedation is between 4 and 8 mg (based on more than 2000 midazolam sedation procedures). The range of these doses is of far greater importance because it illustrates the tremendous individual variability in response to midazolam (and all drugs). In my experience with midazolam as a sole agent for sedation, clinically adequate sedation has been achieved with as little as 0.5 mg (0.5 ml) in some patients, whereas others have received in excess of 10 mg and have not even approached the desired level of sedation.

The following is suggested as a means of determining the maximum dose of midazolam for a given patient:

Midazolam is titrated at a rate of 1 mg (1 ml) per minute until “ideal” sedation is achieved. The average dose of diazepam required to produce this clinical effect is 4 to 8 mg. Once this effect is achieved, titration ceases, the IV infusion is slowed to t.k.o., and the operative phase of treatment is begun (see later discussion).

If, however, a midazolam dose of 8 mg has been administered with the patient demonstrating some, but not close to ideal, clinical sedation, additional midazolam may be titrated up to a total of 10 mg. On the other hand, if the patient has received 8 mg of midazolam but exhibits virtually no signs or symptoms of sedation, it is suggested that the administration of midazolam cease. Experience with benzodiazepines has demonstrated that when no evidence of sedation occurs with an 8-mg dose, the continued administration of midazolam will probably not prove beneficial to the patient, but may increase the risk of occurrence of several dose-related complications. My recommendation to the neophyte at IV moderate sedation is that when a dose of 8 mg midazolam fails to produce any signs or symptoms of clinical sedation, the administration of midazolam is terminated, and the planned dental or surgical procedure is attempted without the administration of additional IV drugs.

The dentist experienced in IV moderate sedation and/or general anesthesia has several additional options available at this time, but in the hands of the dentist without anesthesiology training, the most prudent course of action at this time is to cease IV drug administration and begin the planned procedure. Midazolam is an excellent amnestic drug, and I am no longer surprised by the number of patients who, lacking any obvious signs or symptoms of sedation, do extremely well and have a significant degree of amnesia at the end of the procedure. Should this attempt to treat fail, the patient should be dismissed (following recovery) and rescheduled for a different IV moderate sedation technique at a later date.

Midazolam

Average sedative dose	4-8 mg
Sedative dose range	2.5-10 mg
Maximum dose, no sedation	8 mg
Maximum dose, some sedation	10 mg

Intraoperative Period

Local anesthetic is administered to the patient exactly as it would be if the patient was not sedated. This includes the use of topical anesthetic and all of the other steps involved in the atraumatic administration of local anesthesia.¹⁷ The patient may react to any pain associated with the local anesthetic injection, but this usually is nothing more than a slight moan, grimace, or minor movement. Adequate time should be allowed for the local anesthetic to take effect (3 to 5 minutes) before starting the planned procedure.

During the first 1 to 5 minutes following IV midazolam titration, the level of sedation (CNS depression) is greatest. Although overresponse to the drug can occur, the patient who has overresponded to midazolam will be somewhat sluggish in response to verbal commands, such as “open your mouth.” For this reason, the use of a mouth prop should be considered, at least at the outset of the IV moderate sedation procedure. Within 5 to 10 minutes, the depth of sedation has usually lessened so that the patient’s mouth can be voluntarily kept open. A rubber bite block with a piece of string (dental floss) tied around it or a ratchet type of (Molt) mouth prop may be used at this time (Figure 26-5).

Figure 26-5 Rubber bite block with string (dental floss) tied to it.

Lack of response to verbal command or, more significantly, a lack of response to a painful stimulus (i.e., local anesthetic injection) may indicate that the patient is overly sedated. Lack of response to sensory stimulation is always reason for the dentist to stop treatment and reevaluate the patient’s level of consciousness and airway and ventilatory status (e.g., to “rescue” the patient from unintended entry into the next level of sedation [deep]).¹⁸

Following local anesthetic administration, a rubber dam should be applied, if feasible, for the planned procedure. The rubber dam serves two important functions during IV moderate sedation:

1. It aids in maintaining the mouth in an open position (it may be used in place of the mouth prop).

2. It prevents extraneous material from falling into the posterior part of the mouth, throat, and pharynx.

Treatment begins at this time. Because of the 45- to 60-minute duration of sedation provided by IV midazolam, the dental treatment should be planned to fit into this time period. Midazolam produces a period of anterograde amnesia in most patients, lasting for most of the duration of the dental procedure (if not longer).¹⁸ Potentially painful or traumatic procedures completed during this time will likely not be remembered by the patient later, though they will still respond to the stimulus in a somewhat normal manner when they occur.

Planned properly, as the sedative effect begins to wane (about 30 minutes after drug administration), relatively innocuous procedures can be performed, such as completing restorations, suturing, or adjusting occlusion. In addition, having received local anesthesia earlier, the patient will be pain free at this time and able to tolerate these procedures without complaint. In most patients, actual treatment time, with one initial titrating dose of midazolam, can usually be extended well beyond 1 hour because of the lack of pain and the relative innocuousness of the procedures carried out at the end of the treatment period.

It is uncommon for a patient to require a second dose of midazolam if the duration of the planned procedure was appropriate (about 1 hour). As discussed in Chapter 25, midazolam sedation may be divided into several phases: stage 1: (minutes 1 to 10) good sedation plus amnesia; stage 2: (minutes 11 to 30) “OK” sedation plus amnesia; stage 3: (minutes 31 to 45) sedation wanes (patient more alert), amnesia still present; and stage 4: (minutes 46 to 60): clinical recovery of patient, amnesia may still be present. With entry into the third phase, the patient may opine that he or she feels “normal” once again, and the dentist might be tempted to administer additional midazolam. However, by this time, treatment should be nearing completion, the procedure performed is usually atraumatic, the patient has effective pain management (local anesthesia), and although the patient feels normal, he or she is still anxiety free, if not visibly sedated. Readministration of midazolam is rarely necessary in this typical 1-hour IV moderate sedation procedure.

Occasionally, readministration of midazolam might become necessary to permit successful completion of the procedure. For example, a patient is scheduled for restorative procedures scheduled for about 1 hour. All goes well, but one of the teeth unexpectedly requires endodontic treatment. The patient becomes increasingly aware of the surroundings approximately 45 minutes into the procedure and has become somewhat apprehensive again. The treating dentist has two options: first, to temporarily fill the canal, dismiss the patient, and reschedule for another IV visit or second, to titr/>

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