Intraosseous injections

INQUIRY Anesthesiology Intraosseous injections Background.—Intraosseous injection places a local anesthetic directly into the cancellous bone adjacent to the tooth requiring anesthesia. Studies of the Stabident injection system as a primary injection technique have found success rates (no response to pulp testing) of 90% or higher. Increased heart rate has been reported with intraosseous injection, but studies have found that the increase was limited to 12 to 32 beats/min and did not influence systolic or diastolic blood pressure. Based on the ease of absorption of epinephrine with intraosseous injection, plasma levels of lidocaine may increase, perhaps to toxic levels. The venous blood levels of lidocaine and the heart rate changes occurring after intraosseous injection were compared with those after infiltration injection with use of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine. Methods.—Twenty subjects were randomly assigned in a crossover design to receive an intraosseous injection at 1 appointment and an infiltration injection at a separate appointment. Patients’ blood pressure was determined by pulse oximeter, and venous blood samples were obtained before injection and 2, 5, 10, 15, 20, 25, 30, 45, and 60 minutes after injection. High-performance liquid chromatography was used to assess plasma samples for lidocaine concentrations. Results.—No statistically significant differences were found between the plasma lidocaine levels obtained with the 2 injection techniques. The peak plasma lidocaine levels for maxillary infiltration were obtained at 2 minutes and the mean concentration was 1.07 µg/mL. These levels declined throughout the 60-minute observation period. The highest plasma concentration occurring with infiltration injection was 1.39 µg/mL, occurring 5 minutes after the injection. The peak plasma lidocaine levels for intraosseous injection occurred at 5 minutes, and the mean concentration was 1.05 µg/mL. A decline in plasma levels similar to that noted with the infiltration injection was noted. The

highest plasma concentration occurring with intraosseous injection was 1.33 µg/mL, occurring 10 minutes after the injection. Heart rate transiently increased significantly with the intraosseous injection compared with the infiltration injection, both when the solution was being deposited and 2 minutes after injection. Discussion.—With respect to lidocaine, the intraosseous injection is not considered an intravascular injection technique. With a truly intravascular technique, the resulting anesthetic effect would be minimal or absent because the lidocaine solution would have been deposited into the vascular system and would not remain to induce pulpal anesthesia. The comparison between intraosseous and infiltration injection techniques identified a transient heart rate increase occurring only with the intraosseous technique. The plasma levels of lidocaine were essentially the same regardless of the technique.

Clinical Significance.—Results here argue against the idea of an intraosseous injection being the same as an infiltration injection. While plasma levels of lidocaine were essentially the same for both intraosseous and infiltration routes, intraosseous injections produced a significant increase in heart rate.

Wood M, Reader A, Nusstein J, et al: Comparison of intraosseous and infiltration injections for venous lidocaine blood concentrations and heart rate changes after injection of 2% lidocaine with 1:100,000 epinephrine. J Endodont 31:435-348, 2005 Reprints available from A Reader, Dept of Endodontics, College of Dentistry, The Ohio State Univ, 305 W 12th Ave, Columbus, OH: e-mail: [email protected]

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