Abstract
Use of vasoconstrictors in local anaesthesia is well known. The study was done on 30 patients who underwent removal of bilateral impacted third molars. The aim of the study was to compare the efficacy of lignocaine with clonidine and lignocaine with adrenaline in respect to onset, duration of anaesthesia, and postoperative analgesia along with hemodynamic stability (systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate in intraoral nerve block. The patients were randomly selected of both sexes (male and female) between the age group of 18–40 years. Patients received 2 mL of 2% lignocaine with adrenaline (12.5 μg/mL) on one side and 2 mL of 2% lignocaine with clonidine (15 μg/mL) on the other side at two different appointments. 2 millilitres of drug was administered in both the test group and the control group. Statistically there was significant decrease in intraoperative and postoperative systolic blood pressure, diastolic blood pressure, mean arterial pressure, and heart rate in the lignocaine with clonidine group. The efficacy of clonidine based on visual analog scale was similar to adrenaline. No significant operative complications were observed.
Keywords: Lignocaine, clonidine, adrenaline, visual analog scale, efficacy
Introduction
In oral and maxillofacial surgery, local anesthesia is used in exodontia, minor oral surgical procedures, and in some major surgical procedures. Without vasoconstrictors local anesthetic agents can produce vasodilatation and increases rate of absorption of local anesthetics from injection site. Vasoconstrictors are added to local anesthesia to reduce bleeding from surgical site and to increase the duration of action of local anesthetics.
Materials and Methods
After obtaining permission from ethical committee, 30 healthy patients who reported to our department of oral and maxillofacial surgery with bilaterally impacted third molar were randomly selected of both genders (male and female) between age group of 18 and 40 years.
Surgery was done in two different appointments.
Group 1: Cases in which lignocaine with clonidine was used on one side (test group).
Group 2: Cases in which lignocaine with adrenaline were used on the other side (control group).
Informed consent was taken before the procedure.
A 2% lignocaine with 1:80,000 adrenaline was use to make the concentration of 12.5 μg/mL. To make the concentration of lignocaine + clonidine of 15 μg/mL, 9 mL of 2% xylocaine was mixed with 1 mL ampule of 150 μg/mL of clonidine in a 10 mL syringe. From this syringe, the solution was transferred to 2 mL syringe so that each milliliter contains 15 μg/mL.
Two milliliters of solution for intraoral nerve block was injected with 2% lignocaine with adrenaline (12.5 μg/mL) on one side and 2% lignocaine with clonidine (15 μg/mL) on the other side at two different appointments. Patients were evaluated preoperatively and postoperatively for systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate, and mean arterial pressure and electrical activity of heart by electrocardiography. The response to pressure testing and subjective signs of anesthesia determined the onset and duration of anesthesia. Postoperatively, patients were evaluated to establish the duration of analgesia.
Pain experiences were measured by Visual Analog Scale (VAS) and Verbal Rating Scale (VRS).
The inclusion criteria were healthy patient of 18–40 years with bilaterally impacted third molar. The exclusion criteria were hypertensive and hypotensive patients, pregnancy, patients with liver diseases, kidney diseases and/or a history of allergy to lignocaine.
Results
The results obtained in healthy patients demonstrate that the anesthetic solution with clonidine, as a vasoconstrictor, significantly decreases SBP, mean arterial pressure [Figure 1], and heart rate [Figure 2]. In contrast, after the application of lignocaine with adrenaline, increased heart rate has been observed in surgery. The cardiovascular parameters during anesthesia with clonidine containing local anesthetic solution were more stable than adrenaline group, whereas parameters of local anesthesia were similar in both the groups.[1] Comparison of VAS between the two groups depicts the mean value was not statistically significant [Figure 3]. VRS recorded higher a mean score in the adrenaline group compared with the clonidine group [Figure 4]. These findings may be relevant to dentists endeavoring to find a vasoconstrictor for local anesthetic solution with minimal cardiovascular risk. Multiple variable factors exist, such as technique variability, anatomic variations, complexity of procedure and reporting error. Pain itself is multifactorial; and perception and pain reaction vary greatly among individuals.
Figure 1.
Mean arterial pressure in the two groups
Figure 2.
Comparison of heart rate
Figure 3.
Comparison of visual analog scale
Figure 4.
Comparison of verbal rating scale
Discussion
Using local anesthetics to control pain during minor oral surgery is one of the most important factor. Lignocaine with clonidine combination could be useful and a safe alternative to lignocaine with epinephrine for intraoral anesthesia.[1] Several studies have been carried out using different concentrations of clonidine for enhancement of epidural anesthesia[2] and brachial plexus blocks.[3] These studies showed that effective concentration of clonidine without significant side effects were 150 μg/mL, 90 μg/mL3, 30 μg/mL3, 10 μg/mL3, 5 μg/mL.[4]
It appears that clonidine could be a useful alternative to adrenaline for intraoral anesthesia and may have a role in those with cardiovascular disease or those particularly sensitive to adrenaline.[5]
In a study by Brkovic et al., there was no significant difference in the onset of anesthesia between the clonidine and the epinephrine groups, because the onset of anesthesia primarily depends on the characteristics of local anesthetics.[6]
In the present study, preoperatively the difference in mean SBP and DBP in the clonidine and adrenaline groups were not statistically significant. Intraoperatively, there was a significant increase in SBP and DBP in the adrenaline group compared with clonidine group. Postoperatively a higher mean SBP and DBP were seen in the adrenaline group compared with the clonidine group.
In a study by Brkovic et al.,[1] it was proved that heart rate before anesthesia administration for lidocaine with clonidine group was 85.4 ± 3.1 bpm and decreased significantly 10 min after surgery (80.9 ± 2.8 bpm). In lidocaine with epinephrine group, heart rate significantly increased 10 min after surgery in comparison with the values before anesthesia. With application of lidocaine with epinephrine, increased heart rate was observed after surgery. In cardiovascular patients, clonidine in lidocaine anesthesia given for cervical plexus block produces hemodynamic stability, which was not observed in lidocaine with epinephrine–treated patients in whom significantly increased heart rate was recorded.[2] Clonidine slightly lowers heart rate. This effect was significant at 30, 60, 120, 180 min. Clonidine incrementally reduced stroke volume. As a result there was prolonged fall in cardiac output. Clonidine caused prolonged decrease in cardiac output mainly as a result of reduction of heart rate and stroke volume.[6] Clonidine decreases heart rate by increasing vagal tone and inhibiting cardioaccelerator nerve.[7]
The present study showed the difference in mean heart rate preoperatively and intraoperatively was not so significant between clonidine and adrenaline group but postoperatively significantly lower mean heart rate was seen in clonidine group compared with adrenaline group.
James Eisenach showed that there was no significant statistical difference between clonidine and adrenaline group when intensity of anesthesia was evaluated VAS and VRS. The present study shows 40% of patients in clonidine group had no pain, 43% had just noticeable, 17% had mild pain. Thirty percent of patients in adrenaline group had no pain, 43% had just noticeable pain, and 13% had mild to moderate pain. The difference in mean VAS between the two groups was not statistically significant. No significant association was observed between VRS in adrenaline and clonidine groups.
The total number of pain medication doses taken was significantly lower in clonidine-treated patients, compared with those treated with epinephrine in 24 h postoperatively. The mean duration of analgesia was more with clonidine group compared with adrenaline group indicating that clonidine increases the duration of postoperative analgesia. In the present study, 1 patient showed ST segment depression ≥ 1 mm in clonidine group. Shelf-life of freshly prepared lignocaine with clonidine was 8 h, whereas lignocaine with adrenaline has a proven longer shelf-life. This indicates that, freshly prepared solution of lignocaine with clonidine should be used for every procedure, which may add to the cost of treatment. Patients falling in American Society of Anesthesiologists (ASA) I and ASA II categories were only included in the present study. The cardiovascular soothing effect of clonidine suggests that this drug can be a safe choice to be used in patients in whom adrenaline use was to be avoided.
Footnotes
Source of Support: Nil.
Conflict of Interest: None declared.
References
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