Direct Intravenous Administration

In direct IV administration, a tourniquet is placed on the patient’s arm, engorging the veins, the injection site is prepared, and the needle of the syringe containing the drug(s) is placed into the lumen of the vein, in effect doing the venipuncture with the drug-containing syringe. After ensuring that the needle tip lies within the lumen of the vein (aspiration of blood back into the syringe), the dentist or assistant removes the tourniquet, and the drug is slowly administered into the vein. Following drug administration, the needle is removed from the vein, pressure is applied to the site to stop bleeding, and the planned treatment begun. No access to the vein is maintained during the procedure (Figure 22-1).

Figure 22-1 Direct IV drug administration. Blood is aspirated into syringe before injection to determine that needle is still within lumen of vein.

Needle Maintained in the Vein Without Continuous Infusion

When the needle is maintained in the vein without an infusion, the tourniquet is placed, the veins are engorged, and the tissues are prepared in the usual manner. A winged infusion set or a hollow metal needle is used for venipuncture. Following successful venipuncture, the tourniquet is removed, and the syringe (without a needle attached) is connected to the needle that has been left in the vein and taped into place. After the drug is titrated to effect, the syringe is detached from the needle, and a second syringe containing a solution such as sterile water for injection is attached to the needle. The dental procedure is begun, with the dentist or assistant periodically flushing the needle with 1 ml of solution to keep the vein patent (Figure 22-2).

Figure 22-2 Needle maintained in the vein without continuous infusion.

Continuous Intravenous Infusion

With a continuous IV infusion, an indwelling needle or catheter is attached to a length of tubing that in turn is connected to a bag of IV infusate. The same venipuncture procedure is carried out that was described for the first two techniques. Following removal of the tourniquet, the flow of IV solution is started, and the needle or catheter is secured. The IV drugs are administered through an injection port on the tubing, and the drug syringe is then removed. The rate of the IV infusion is adjusted to maintain a slow flow that will prevent needle occlusion during the dental procedure, which is then begun (Figure 22-3).

Figure 22-3 Continuous IV infusion.

Choice of Solution

A number of fluids are available for IV therapy. Although the type of solution chosen is of potential significance in the hospitalized patient receiving prolonged IV therapy, for a short-duration IV procedure (less than 1 hour to several hours’ duration) on a relatively healthy patient (ASA 1 or 2), the choice of infusate becomes academic. Solutions available for IV administration include the following:

Solution	Abbreviation
Lactated Ringer’s	LR
Sterile water for injection	SW
5% dextrose in water	D5W
Sodium chloride injection	NS

Although other infusion solutions are available, these represent the most commonly used solutions.

In the ambulatory American Society of Anesthesiologists (ASA) 1, 2, or 3 patient considered as a candidate for IV moderate sedation on an outpatient basis, there will be no contraindication to the use of any of these solutions. The question of whether a patient with insulin-dependent diabetes mellitus (type 1, or IDDM) should receive 5% dextrose in water often arises—will this solution elevate the patient’s blood sugar level?

The answer is that a 5% dextrose and water solution is not contraindicated in the diabetic patient. First, the concentration of dextrose (5%) is not great enough to produce any significant change in the blood sugar level of this patient.¹ Second, as stressed in Chapter 26, the patient receiving IV moderate sedation will be requested to fast (be NPO) for approximately 4 hours before the planned procedure. The patient arrives at the dental office with a decreased blood sugar level, perhaps not quite hypoglycemic but definitely not hyperglycemic. The addition of approximately 250 to 500 ml of 5% dextrose and water will produce a slight elevation in blood sugar level, a desirable effect at this time. It must be remembered that when a person with diabetes becomes clinically hypoglycemic, treatment of choice is the administration of 50% dextrose, a solution 10 times that which is infused during IV sedation.

Volume of Solution

All IV infusion solutions (fluids) are packaged in plastic bags (Figure 22-4).

Figure 22-4 IV infusion solution of lactated ringers (LR) (A) 5% dextrose in water (D₅W) (B).

IV fluids are available in a variety of sizes. Most commonly used sizes include 1000, 500, and 250 ml. The 1000-ml (1-L [liter]) size is common in the hospital setting when a patient is receiving long-term IV therapy. The patient usually receives 3 L of IV fluid daily. Under a general anesthetic, during which time the patient must be kept hydrated throughout the surgery, 1-L bags are also commonly used. Use of the 1-L bag for dental outpatient procedures is not the most highly recommended, although there is no significant reason why it should not be used. However, for the typical IV procedure in the dental office, the 1-L bag is simply too large. For example, during a 1-hour procedure, the typical patient may receive 125 to 200 ml of infusion fluid. At the conclusion of the procedure, the infusion bag represents one of the three items in the IV armamentarium that must be discarded. It is a single-use item, and must never be reused despite the fact that, in this example, approximately 800 ml of infusate remains unused.

The 250-ml or 500-ml bags of IV fluid represent the most nearly ideal sizes for the typical 1- to 4-hour dental IV moderate sedation procedure. With proper management of the flow rate (as discussed in Chapter 26), a 250-ml or 500-ml bag can be made to last for 3 to 4 hours.

The solution found within the IV bag is sterile. However, problems with contaminated fluids have developed in the past.² Care must be exercised by the user of such fluids to try to ensure their continued sterility. Administration of contaminated fluids directly into the cardiovascular system of the patient can produce bacteremia or septicemia and has led to deaths and significant morbidity.³

The following should be checked before using a bag of solution: