chapter 21 Intravenous Moderate Sedation: Rationale
ADVANTAGES
1. The onset of action of intravenously administered drugs is arguably the most rapid of all techniques discussed in this book. Hand-heart-brain circulation time is approximately 20 to 25 seconds. Although some individual variation exists in this and in the onset of action for different drugs, overall, the IV route of drug administration permits the most rapid onset of action (or at least almost as rapid an onset as inhalation drugs).
2. Because of the rapid onset of action of most intravenously administered drugs, the drug dosage can be tailored to meet the specific needs of the patient. The guesswork associated with determining proper dosage of an orally, intranasally, or intramuscularly administered drug is eliminated when the IV route is used. This concept of individualizing drug dosages is termed titration and represents one of the most important safety features associated with IV drug administration.
3. Because of the rapid onset of action of most IV drugs, the dentist is able to provide the patient with a suitable level of sedation. The level of sedation must never, of course, exceed that level to which the dentist has been trained. Minimal, moderate, and deep levels of sedation can all be achieved via the IV route, and the dentist must always remain cognizant of his or her limitations, as based on prior experience and training.
4. The recovery period for most intravenously administered drugs is significantly shorter than that seen for the same drug administered via the oral, rectal, intranasal (IN), or intramuscular (IM) routes. Recovery from intravenously administered drugs will, however, be considerably longer and less complete than that following nitrous oxide-oxygen (N2O-O2) inhalation sedation.
5. In the continuous IV infusion technique recommended in this book, a patent vein is maintained throughout the procedure. This facilitates reinjection of any additional central nervous system (CNS)–depressant drug (although this is rarely necessary). However, the major significance of maintaining a patent vein is that through it a portal exists for the administration of any rescue (emergency) drugs that may be required in the unlikely event an emergency arises during IV therapy.
6. The side effects of nausea and vomiting are extremely uncommon when drugs are administered intravenously, as recommended.
7. Effective control of salivary secretions is possible through the IV administration of anticholinergics. This will be of benefit to the dentist during various types of dental therapy, such as the taking of impressions.
8. The gag reflex is diminished. Patients receiving IV moderate sedation rarely experience difficulty with gagging. This action is similar to that occurring with N2O-O2 inhalation sedation. If the only requirement in a patient is to minimize the gag reflex, inhalation sedation is preferred over IV moderate sedation. Only in the event that inhalation sedation fails to diminish the hyperactive gag reflex should IV moderate sedation be employed solely for this purpose.
9. Many of the drugs administered intravenously for sedation effectively diminish motor disturbances (e.g., seizure activity and cerebral palsy), making this route advantageous for the seizure-prone patient.
10. The ability to readily gain IV access (venipuncture) may prove to be important in any emergency situation. Although antidotal drug therapy is not recommended as the initial step in the effective management of emergency situations, the ability to establish an IV line provides immediate access to the cardiovascular system should it become necessary to administer drugs to the victim. Through the use of IV moderate sedation on a regular basis, the dentist is better able to maintain proficiency in the technique of venipuncture.
DISADVANTAGES
1. Venipuncture is necessary. Although most adult patients tolerate venipuncture with little or no difficulty, some patients are psychologically unable to “handle” needles anywhere in their body. Children may be particularly difficult to manage via this route because veins are proportionally smaller in smaller patients, making venipuncture itself more difficult. Younger children requiring IV moderate sedation will usually pose severe management problems (the “precooperative” patient) or be physically unable to control themselves. Not all patients, even adults, have veins that are easy to visualize and gain access to with a needle. Probably the most significant challenge facing the dentist learning IV moderate sedation is to develop a degree of proficiency at venipuncture. Venipuncture is a learned skill, one that becomes easier to perform as experience is gained.
2. Complications may arise at the venipuncture site. As discussed in Chapter 27, a variety of minor and some major complications can develop at the venipuncture site. These include hematoma, phlebitis, and intraarterial injection of a drug.
3. Monitoring of the patient receiving IV moderate sedation must be more intensive than that required in most other moderate sedation techniques. Because intravenously administered drugs act rapidly, the entire dental team must be trained to assess the physical and mental status of the patient throughout the procedure. The greater the depth of sedation (deep > moderate > minimal), the greater is the need for increased patient monitoring.
4. Recovery from intravenously administered drugs is not complete at the end of the dental treatment. All patients receiving any intravenously administered CNS depressant must be escorted from the dental office by a responsible adult companion.
5. Although the depth of sedation provided by intravenously administered drugs can be increased rapidly (by administration of additional drug), the converse is not true. Many intravenously administered drugs cannot be reversed by specific drug antagonists. Although antagonists do exist for several drug groups, specifically opioids, benzodiazepines, and anticholinergics, they are not recommended for routine administration.1–3 Should a patient become overly sedated (deep instead of moderate; moderate instead of minimal), the initial, and most effective, management in all situations is the maintenance of basic life support: assess the patient’s airway, assist or support ventilation, and provide for the effective circulation of oxygenated blood. Following these steps (P-A-B-C [basic life support]) consideration may be given to antidotal drug therapy.
Box 21-1 summarizes the advantages and disadvantages of the IV route of drug administration.
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