Clinical Trial: Methemoglobin Levels in Generally Anesthetized Pediatric Dental Patients Receiving Local Anesthetics

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Methemoglobin Levels in Generally Anesthetized Pediatric Dental Patients Receiving Prilocaine Versus Lidocaine

Brief Summary: To establish and compare maximum methemoglobin blood levels and times to maximum methemoglobin blood levels following the administration of the injectable local anesthetics prilocaine and lidocaine when used for dental treatment in pediatric patients under general anesthesia. Patients will be randomized into three equal study groups. Two of the study groups will receive local anesthetic and the third group will not. Methemoglobin blood levels will be non-invasively monitored and recorded throughout dental treatment for all groups using a Masimo Radical-7 Pulse Co-Oximeter device.

Detailed Summary:

Methemoglobin is an abnormal hemoglobin that is formed by the oxidation of one or more of the four heme groups of hemoglobin by oxygen and other exogenous oxidizing agents. The injectable local anesthetic prilocaine that is routinely used in the medical and dental professions is a well known inducer of methemoglobin. The injectable local anesthetic lidocaine has also been suggested to be associated with the development of methemoglobin; however, there is no direct evidence supporting these claims.

The concern with methemoglobin is that it is a dose-dependent toxin. The oxidation of one of the iron groups from a ferrous state to a ferric state alters the molecular structure of the hemoglobin molecule and impairs its ability to bind oxygen. This ultimately results in less oxygen being delivered to peripheral tissues and less carbon dioxide being removed which can cause tissue hypoxia. A small amount (0-2%) of methemoglobin is normally present in the blood as a result of the oxidation of hemoglobin by the prototypical oxidant oxygen. However, when an individual is exposed to an exogenous oxidizing agent of sufficient dosage and potency, methemoglobin levels can rise above 2% and a person can develop what is known as acquired methemoglobinemia. Signs of cyanosis as a result of acquired methemoglobinemia usually become present when methemoglobin blood levels rise above 15%.

Despite the injectable local anesthetic prilocaine being a well known inducer of methemoglobin and lidocaine being a speculated inducer, there are no documented studies or trials in the dental literature as to the extent of the amount of methemoglobin that is formed following the routine use of these injectable local anesthetics.

This investigation will examine the peak blood levels of methemoglobin and the t
Sponsor: Loma Linda University

Current Primary Outcome: Peak Methemoglobin Blood Levels [ Time Frame: Measured at 10 second intervals during dental treatment for an average of 2 hours ]

The maximum percentage of methemoglobin in blood


Original Primary Outcome: Peak Methemoglobin Blood Levels [ Time Frame: 10 second intervals over 2 hour period of dental treatment ]

Methemoglobin Blood Levels will be measured non-invasively by a Masimo Radical-7 Pulse Co-Oximeter. Device will monitor and record methemoglobin levels at 10 second intervals. Maximum methemoglobin levels will be documented.


Current Secondary Outcome:

  • Time to Peak Methemoglobin Blood Levels [ Time Frame: Measured at 10 second intervals during dental treatment for an average of 2 hours ]
    The length of time between the administration of local anesthetic (Prilocaine and Lidocaine Groups) or start of restorative dental procedures (No local anesthetic Group) and the time at which the maximum methemoglobin blood level is observed.
  • Delta Methemoglobin Blood Level [ Time Frame: From administration of local anesthetic or start of restorative procedures to time at which maximum methemoglobin blood level was documented during dental treatment for an average of 2 hours ]
    Change in percentage of methemoglobin in blood from baseline level to peak level


Original Secondary Outcome: Time to Peak Methemoglobin Blood Levels [ Time Frame: 10 second intervals over 2 hour period of dental treatment ]

This will be the total length of time from the time of local anesthetic administration to the time the maximum methemoglobin blood level is observed.


Information By: Loma Linda University

Dates:
Date Received: July 25, 2011
Date Started: August 2011
Date Completion:
Last Updated: March 25, 2014
Last Verified: March 2014