Increase in the threshold of pain and touch sensation in the human face with clonidine plus 30% nitrous oxide

Anesthetic Success Using Nitrous Oxide and a Combination of Lidocaine/Clonidine for the Inferior Alveolar Nerve Block and the Effects on Blood Pressure and Pulse in Patients with Symptomatic Irreversible Pulpitis: A Prospective, Randomized, Double-blind Study

INTRODUCTION

The pulpal anesthetic success rates for an inferior alveolar nerve block (IANB) alone in patients presenting with symptomatic irreversible pulpitis are less than adequate. Nitrous oxide and clonidine have shown increases in IANB success when administered individually, but their success has not been evaluated when used together. The purpose of this prospective, randomized, double-blind study was to determine the effect of nitrous oxide/oxygen plus an IANB using lidocaine/clonidine on the success of the IANB in patients with symptomatic irreversible pulpitis and to evaluate the effect of clonidine on blood pressure and pulse.

METHODS

Sixty-two emergency patients experiencing moderate to severe pain and a diagnosis of symptomatic irreversible pulpitis were enrolled. Subjects were randomly divided into 2 groups and received nitrous oxide/oxygen and an IANB using 2% lidocaine with either 27 μg clonidine or 18 μg epinephrine as vasoconstrictors. Blood pressure and pulse were recorded before and during the emergency endodontic treatment. Anesthetic success was defined as no or mild pain upon access and instrumentation of the canals.

RESULTS

The pulpal anesthetic success rate in both treatments was 58%, with no significant difference between the groups. There was no statistically significant difference in pulse or systolic blood pressure with the use of clonidine compared with epinephrine. Diastolic blood pressure was significant.

CONCLUSIONS

The use of nitrous/oxide plus the addition of lidocaine/clonidine for the IANB in teeth with symptomatic irreversible pulpitis resulted in no statistically significant difference in anesthetic success of the IANB. There were no statistically significant differences in pulse or systolic blood pressure with the use of clonidine compared with epinephrine; diastolic blood pressure was significant.

Oral clonidine pre-treatment and diazepam/meperidine sedation

Clonidine has recently been used as a pre-operative medication and sedative/anxiolytic drug. Its extended duration of action makes it suitable for longer procedures. In this randomized, crossover, placebo-controlled clinical trial, we characterized the effects of oral clonidine pre-treatment on intravenous diazepam/meperidine sedation using the bi-spectral index (BIS) in 13 participants. Clonidine significantly increased the numbers of BIS-depressed readings and percent memory loss during sedation, while reducing total diazepam and post-operative analgesic dosages by 44% and 55%, respectively. Systolic, diastolic, and mean arterial blood pressures, as well as pulse rates, were reduced. Respiratory rate, oxygen saturation, end-tidal CO(2), and recovery from sedation were unchanged. Participants, surgeons, and sedationists preferred clonidine over the placebo. Clonidine pre-treatment increased and prolonged sedation and amnesia and stabilized vital signs while significantly decreasing diazepam and post-operative analgesic usage. These results suggest that pre-operative clonidine administration could be a useful supplement to intravenous sedation for dental procedures of long duration.

Oral clonidine pretreatment prior to venous cannulation

Clonidine is a preferential alpha-2 agonist drug that has been used for over 35 years to treat hypertension. Recently, it has also been used as a preoperative medication and as a sedative/anxiolytic drug. This randomized, double-blind, placebo-controlled crossover clinical trial characterized the effects of oral clonidine pretreatment on intravenous catheter placement in 13 patients. Parameters measured included the bispectral index (BIS), Observer's Assessment of Alertness/Sedation Scale (OAA/S), frontal temporal electromyogram (EMG), 30-Second Blink Count (Blink), Digit Symbol Substitution Test (DSST), State Anxiety Inventory (SAI), fingertip versus forearm skin temperatures, and multiple questionnaires. Oral clonidine significantly decreased SAI scores, OAA/S, EMG, and Blink, but did not cause statistically significant BIS or DSST reductions. Subjects preferred oral clonidine pretreatment prior to venipuncture compared to placebo. Questionnaires also indicated that clonidine provided minimal sedation, considerable anxiolysis, and some analgesia. Fingertip versus forearm skin temperature differentials were decreased. Reduced fingertip versus forearm temperature differentials suggest increased peripheral cutaneous blood flow prior to venous cannulation. Oral clonidine pretreatment not only helped control patient anxiety and pain but also provided cardiovascular stability.

Comparison of the effect of video glasses and nitrous oxide analgesia on the perceived intensity of pain and unpleasantness evoked by dental scaling

The aim of this study was to evaluate whether distraction induced by video glasses had an effect on the perceived intensity of pain and unpleasantness during dental scaling compared with the effect of nitrous oxide (N(2)O) analgesia. The pain stimulus was dental scaling (removal of dental calculus) with an ultrasonic scaler. As a standardised, non-dental painful stimulus, Von Frey filaments were used. A total of 26 patients with superficial chronic periodontitis were enrolled in this randomised, controlled clinical study. The effect of video glasses was compared with N(2)O in one session and the effect of video glasses versus a control situation in another. The patients rated the intensity of pain and unpleasantness evoked by dental scaling and Von Frey filament stimulation on 100-mm visual analogue scales (VAS). For dental scaling, there was no effect of video glasses on the perceived pain (p=0.85) or unpleasantness (p=0.73) nor of N(2)O (p=0.69 and p=0.51, respectively) compared with the control situation. Similarly, no significant difference was found between VAS scores in the video glasses and N(2)O session (p=0.48, p=0.58). A significant effect of video glasses and N(2)O(p<0.008) was found on the perceived pain intensity produced by Von Frey filament stimulation compared with the control situation, but no significant difference was seen between these methods (p=0.07). Post-treatment interviews of the patients revealed that 81% of the patients in the video and 65% in the N(2)O session stated that the method had some beneficial effect on their overall experience of the treatment situation. In conclusion, administration of video glasses or N(2)O did not affect the perceived intensity of pain and unpleasantness evoked by dental scaling.