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| ORIGINAL ARTICLE |
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| Year : 2016 | Volume
: 9
| Issue : 1 | Page : 83-91 |
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Efficacy of intravenous regional anesthesia with dexmedetomidine: local addition versus systemic infusion
Ayman A Rayan1, Ayman A El Sayed2
1 Department of Anesthesia, Menoufia University, Cairo, Egypt
2 Department of Anesthesia, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| Date of Web Publication | 17-Mar-2016 |
Correspondence Address:
Ayman A Rayan
Department of Anesthesia and Intensive Care, Faculty of Medicine, Menoufia University, Menoufia 71411
Egypt
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/1687-7934.178885
Background
Intravenous regional anesthesia (IVRA) is a type of regional anesthesia that is administered using a pneumatic tourniquet isolating the limb from the systemic circulation. IVRA has been limited by tourniquet pain and the inability to provide postoperative analgesia. Thus, to improve the quality of IVRA and avoid these problems, additives are added to local anesthetics. We designed this study to evaluate the efficacy of IVRA by using dexmedetomidine locally versus an intravenous systemic infusion.
Materials and methods
Overall, 60 ASA I-II patients of either sex, 18-65 years old, scheduled for hand or distal forearm surgeries were studied. Patients were divided randomly into three groups (20 patients each): group L received 3 mg/kg lignocaine completed to 40 ml normal saline (NS), group LD1 received 0.5 μg/kg dexmedetomidine added to 3 mg/kg lignocaine completed to 40 ml NS, and group LD2 received 3 mg/kg lignocaine completed to 40 ml NS plus an intravenous infusion of 1 μg/kg dexmedetomidine over 10 min 15 min before IVRA, followed by maintenance of dexmedetomidine infusion at the rate of 0.02-0.06 μg/kg/min. Onset and recovery times of sensory and motor blocks, tourniquet pain, rescue analgesia, and visual analogue scale postoperatively were monitored.
Results
Onset and recovery times of sensory and motor blocks were shorter in group LD1 compared with the other two groups. Time of tourniquet pain was found to be prolonged in groups LD1 and LD2 compared with group L. The use of rescue fentanyl and tramadol in the first 24 h was increased in group L versus both the other two groups.
Conclusion
Local addition of dexmedetomidine to IVRA produced shorter onset and slower recovery of sensory and motor blocks compared with systemic infusion of dexmedetomidine. The durations of postoperative analgesia and rescue analgesia were comparable between both groups using dexmedetomidine either locally or systemically. Keywords: dexmedetomidine, intravenous regional anesthesia, local addition, systemic infusion
How to cite this article:
Rayan AA, El Sayed AA. Efficacy of intravenous regional anesthesia with dexmedetomidine: local addition versus systemic infusion
. Ain-Shams J Anaesthesiol 2016;9:83-91 |
How to cite this URL:
Rayan AA, El Sayed AA. Efficacy of intravenous regional anesthesia with dexmedetomidine: local addition versus systemic infusion
. Ain-Shams J Anaesthesiol [serial online] 2016 [cited 2023 Nov 28];9:83-91. Available from: http://www.asja.eg.net/text.asp?2016/9/1/83/178885 |
| Introduction | |  |
Intravenous regional anesthesia (IVRA) is a type of regional anesthesia that is administered using pressure to the proximal extremity with a pneumatic tourniquet isolating the limb from systemic circulation. This method was first used by August Bier. In 1963, Holmes used lignocaine as a local anesthetic (LA) and this technique gained success and popularity [1],[2] . IVRA has been limited by tourniquet pain and the inability to provide postoperative analgesia [3] . One of the problems with IVRA was the absence of a prolonged analgesic effect after tourniquet release. To improve the quality of IVRA block, the addition of various opioids to LAs has been investigated, with controversial results. A meta-analysis concluded that opioids lack a significant effect [4] . Dexmedetomidine, a potent a-2-adrenoceptor agonist, is approximately [5] times more selective toward a-2- adrenoceptors than clonidine. Dexmedetomidine has been shown to decrease the anesthetic requirements by up to 90% and to induce analgesia in rats, volunteers, and patients [6],[7] . This study was designed to evaluate the efficacy of IVRA when dexmedetomidine was used as an additive to lignocaine versus an IV systemic infusion. We aimed to investigate the onset and recovery time of sensory and motor blocks, the quality of anesthesia, hemodynamic changes, rescue analgesia, and pain and sedation, complications of the technique, and the side effects of study medications.
| Materials and methods | | |
The present study was carried out on patients attending the orthopedic department in Prince Salman Hospital (Tabuk, Kingdom of Saudi Arabia) from May 2013 to September 2014.
Selection of cases
The study was approved by the Hospital Ethics Committee and a written informed consent was obtained from each patient. We studied 60 ASA class I and II patients of either sex, aged 18-65 years scheduled for hand or distal forearm surgeries (e.g. ganglion excision, carpal tunnel release). A detailed assessment of history, physical examination, routine investigations, and any special investigation, if required, were performed before the surgery.
Criteria for exclusion
- Patient refusal.
- Surgery expected to last more than 90 min.
- Patient with severe peripheral vascular disease (e.g. Raynaud's disease) or neurological disease.
- Patients with sickle cell anemia.
- Patients using analgesics within the last 24 h before surgery.
- A history of allergy to any of the study medications.
During the preoperative visit, the procedure was explained to the patients and they were taught how to represent postoperative pain on the visual analogue scale (VAS).
Design of study
Patients were divided randomly into three groups (20 patients each):
- Group L received 3 mg/kg of Lignocaine 2% (20mg/ml) (preservative-free) (Hospira, Inc., Lake Forest, IL 60045, USA) diluted with normal saline (NS) to 40 ml volume.
- Group LD1 received 0.5 μg/kg dexmedetomidine (Precedex 200 μg/2 ml; Abbott, North Chicago, Illinois, USA) added to 3 mg/kg lignocaine (preservative free) 2% diluted with NS to 40 ml volume.
- Group LD2 received 3 mg/kg lignocaine (preservative free) 2% diluted with NS to 40 ml volume plus an intravenous infusion of 1 μg/kg dexmedetomidine in 20 ml NS over 10 min 15 min before IVRA and then dexmedetomidine was maintained at the rate of 0.02-0.06 μg/kg/min [Figure 1].
 | Figure 1: Flow chart of patients. IVRA, intravenous regi onal anesthesia
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Technique
Premedication
No premedications.
Monitoring
Basic monitors [heart rate (HR), mean arterial blood pressure (MAP), and peripheral oxygen saturation (SpO 2 )] were attached (Cato PM 8040; Drager, Lübeck, Germany). The HR and MAP were recorded every 5 min throughout the procedure.
Before starting the procedure, it was ensured that resuscitation equipment and emergency drugs were at hand to deal with any side effects. Before establishing the IVRA, two 20 G cannulas were placed: one in a vein on the dorsum of the operative hand and the other in the opposite upper limb for an intravenous crystalloid infusion. All patients received an oxygen mask at 4 l/min during the surgery.
Patients were randomized using a computer-generated before IVRA. The study design was a prospective, randomized, blind placebo-controlled trial. A randomization list was generated and identical syringes containing each drug were prepared by personnel blinded to the study. A padded double-cuff pneumatic tourniquet (Tourniquet 2800 ELC, UMB; Medizintecknik, GmbH, Berlin, Germany) was tested and positioned around the arm. The operative arm was elevated for 3 min at 90°, then exsanguinated with an Esmarch bandage, the proximal cuff was inflated to 250 mmHg, and then the bandage was removed. Circulatory isolation of the arm was verified by inspection, absence of radial pulse, and loss of pulse oximetry tracing in the ipsilateral index finger. The solution was injected over 90 s by an anesthesiologist blinded to the drugs injected.
Assessment of sensory blockade
After injecting the drug (considered as 0 time), the onset time of sensory blockade was determined by pinprick using a fine 22 G short-beveled needle. Sites used for sensory assessment included the thenar eminence (median nerve), the hypothenar eminence (ulnar nerve), and the first web space (radial nerve). Loss of pinprick sensation in the three skin areas was considered a complete sensory blockade.
Assessment of motor blockade
The patient was asked to move his/her finger; inability to do so was considered a motor blockade. The distal cuff was inflated to 250 mmHg, followed by deflation of the proximal cuff and the first tourniquet tolerance was calculated.
Assessment of postoperative pain
Postoperatively, the pain score was recorded using VAS from 0 to 10 (0 = no pain, 10 = most severe pain). Intravenous tramadol was administered as a rescue analgesia when VAS values reached at least 3. The duration of postoperative analgesia was noted from deflation of the distal tourniquet to a VAS score of 3.
Assessment of sedation
Sedation was assessed by Ramsay sedation scale [Table 1].
Measurements
- Patient data.
- HR, MAP, and SpO 2 were monitored throughout the duration of the procedure until the end of the operation, before (baseline reading) and after tourniquet application, recorded every 5 min after the injection of LA by an anesthesia resident, who was aware of the medication administered. Hypotension (20% decrease from the baseline value) was treated with intravenous ephedrine (5 mg bolus); bradycardia (20% decrease from the baseline value) was treated with intravenous atropine (0.5 mg bolus).
- Onset time of sensory block (the time elapsed from injection of the study drug to the achievement of sensory block in all dermatomes).
- Onset time of motor block (the time elapsed from injection of the study drug until complete motor block).
- Recovery time of sensory block (time elapsed after distal tourniquet deflation up to recovery of pain in all dermatomes determined by a pinprick test).
- Recovery time of motor block was recorded (time elapsed after distal tourniquet deflation up to recovery of motor block).
- Number of patients requiring intraoperative fentanyl (VAS ≥3).
- Amount of rescue intraoperative fentanyl (μg) (fentanil citrate; Abbott) was recorded. [Intraoperative rescue fentanyl 1 μg/kg was provided for pain treatment when required (VAS was ≥3)].
- Total consumption of tramadol in the first 24 h postoperatively.
- Tolerance time of the first proximal tourniquet (min) (the duration of inflation of proximal tourniquet till its deflation because of pain).
- Time of the second (distal) tourniquet pain (min) (the duration of inflation of distal tourniquet until its deflation because of pain).
- The duration of postoperative analgesia (min) [the time to the first analgesic requirement (the time elapsed after distal tourniquet release to the patient's first request for analgesics) was noted].
- Postoperative pain score (VAS assessment in PACU).
- Sedation score by the Ramsay sedation scale (1 h in PACU).
- The anesthetic conditions [a four-point Verbal Numerical Scale (VNS)] (at the end of the operation, the attending anesthetist, who was blinded to the studied groups, was asked to assess the anesthetic conditions according to a four-point VNS, where a score of 4 = excellent, indicated no complaint from the patient; 3 = good, minor complaint with no need for supplemental analgesics; and 2average, moderate; if the score was 1 = unsuccessful, general anesthesia was administered).
- The operative conditions (after the operation, the surgeon who was unaware of the medication administered was asked to assess the operative conditions according to the following numeric scale: 0 = unsuccessful, 1 = poor, 2 = acceptable, and 3 = perfect. All of the operations were performed by the same surgeon).
- Patients were also observed for complications such as the occurrence of unwanted central nervous system manifestations (tinnitus, dizziness, circumoral tingling, seizures, and coma), effects on the cardiovascular system such as hypotension and bradycardia (20% decrease from the baseline value) or arrhythmias, a peripheral oxygen saturation less than 90%, nausea and vomiting, and skin rash during the postoperative period, and a suitable management plan was implemented as clinically indicated.
Measurements in all patients were performed by the same individual. When the proximal tourniquet became painful, the distal cuff was inflated to the same pressure, followed by the release of the proximal cuff. In case of unsuccessful block, general anesthesia was administered. The tourniquet was not deflated before 40 min from injection of the anesthetic solution and was not inflated for more than 1.5 h. At the end of surgery, tourniquet deflation was performed using the cyclic deflation technique. After surgery, patients were transferred to the PACU, where they were monitored and received oxygen through a face mask at 4 l/min. During the study period, these measurements were recorded by an anesthesiology resident who was unaware of the medication that was administered. Following completion of surgery, the tourniquet cuff was deflated using the repeated deflation reinflation technique (cuff deflated for 10 s and reinflated for 1 min); this sequence was repeated three times.
Sample size
A power analysis for sample size suggested that a minimum 18 patients in each group with an a error level 5% corresponds to a 95% confidence, and the mean amount of rescue intraoperative fentanyl was 68.0 μg in group L and 35.4 μg in group LD1 with an SD of 18.6 and 15.5, respectively. The statistical power was 100%.
Statistical analysis
Data were analyzed using the SPSS statistical package, version 17 (SPSS Inc., Chicago, Illinois, USA). Results were presented as mean ± SD, [median (range) (interquartile range)], number, and percentage. Analysis of variance and Student's t-test were used for comparison between the three groups for parametric (quantitative) data. The χ2 -test was used for nonparametric (qualitative) data. For the comparisons, P less than 0.05 was considered to be statistically significant. The comparisons were considered as not significant (P > 0.05), significant (P < 0.05), or highly significant (P < 0.001) in a confidence interval of 95%.
| Results | | |
Patients' characteristics are shown in [Table 2]; a total of 60 patients were enrolled in the study (20 patients in each group). Among the patients, none was excluded from the study because of technical failure and all patients completed the study. There were nonsignificant differences (P > 0.05) in age, sex, weight, height, ASA, duration, and type of surgery.
HR changes are shown in [Table 3], which shows a significant decrease in the HR in group LD2 in comparison with the other two groups at 15, 20, 25, 40, and 55 min (P > 0.05). | Table 3 HR changes at different time intervals following IVRA in three groups
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MAP changes are shown in [Table 4], which indicate a significant decrease in MAP in group LD2 in comparison with the other two groups at 15, 20, 40, and 55 min (P > 0.05). | Table 4 MAP changes at different time intervals following IVRA in three groups
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Onset sensory block time was shorter in group LD1 versus both the other groups (P = 0.0136), whereas onset motor block time was shorter in group LD1 versus both other the groups (P = 0.0109). Sensory block recovery time was significantly slower in group LD1 in comparison with both the other groups (P = 0.016), whereas motor block recovery time was highly significantly slower in group LD1 in comparison with both the other groups (P = 0.0001) [Table 5] and [Figure 2].
In [Table 6], it is shown that the number of patients who needed intraoperative rescue fentanyl was significantly increased in group L [15(75%)] in comparison with both the other groups LD1 and LD2 (P = 0.0004), whereas the amount of intraoperative rescue fentanyl was significantly decreased in groups LD1 and LD2 in comparison with group L (P < 0.0001); the total consumption of tramadol in the first 24 h postoperatively was significantly increased in group L versus groups LD1 and LD2 [Figure 3]. | Figure 3: Number of patients who needed intraoperative fentanyl, mean intraoperative fentanyl, and mean total consumption of tramadol in the first 24 h postoperatively. VAS, visual analogue scale
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 | Table 6 Number of patients who needed intraoperative fentanyl, intraoperative fentanyl, and total consumption of tramadol in the first 24 h postoperatively
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Anesthetic conditions according to a four-point VNS that were determined by the anesthesiology resident were significantly better in both groups LD1 and LD2 versus group L; it was [3 (2-4)] in group L versus [4 (3-4)] in groups LD1 and LD2 (P < 0.05). Also, the operative conditions according to the numeric scale used by the surgeon [2 (2-3)] in group L and [3 (2-3)] in groups LD1 and LD2 were found to be better in group LD1 and LD2 versus group L (P < 0.05) [Table 7].
Postoperative VAS was significantly higher at 30, 60, 90,120, 150, and 180 min in group L in comparison with groups LD1 and LD2 [Table 8].
No major complications were encountered through the study period and no patient needed any intervention because of perioperative hemodynamic or respiratory problems. Minor side effects of LA were the most prevalent adverse events after the completion of surgery and deflation of the upper arm tourniquet; two patients in group L, one patient in group LD1, and no patient in group LD2 experienced tinnitus, light headedness, headache, and circumoral numbness compared with the patients in the forearm group. These side effects were transient and only required monitoring of the patients and reassurance.
| Discussion | | |
Dexmedetomidine is an a-2 agonist that produces sedation and anxiolysis by binding to a-2 receptors in the locus ceruleus, which reduces the release of norepinephrine and inhibits sympathetic activity as well as producing analgesia through binding to adrenoreceptors in the spinal cord [5] . The IVRA technique is used widely for surgeries of the upper limbs because it is considered a safe technique, with fewer complications [9] . The advantages of IVRA are rapid onset of analgesia within 15 min and good muscular relaxation, whereas the disadvantages are tourniquet pain, limited duration of surgery, and absence of postoperative analgesia [10] . Dexmedetomidine reduces the requirements of opioid or nonopioid analgesics when used as a premedication and is effective before IVRA by reducing the patient's anxiety, sympathoadrenal responses, and opioid analgesic requirements, but it does not reduce tourniquet pain [11] . In our study, intraoperative rescue fentanyl and consumption of tramadol in the first 24 h postoperatively were reduced in groups LD1 and LD2 versus group L. Esmaoglu et al. [12] confirmed that addition of dexmedetomidine to lignocaine in IVRA improved the quality of anesthesia and decreased the analgesic requirements. We found in this current study that addition of 0.5 μg/kg dexmedetomidine to the lignocaine for IVRA led to a significant decrease in the onset times of sensory and motor blockade; also, recovery times of sensory and motor blockade were significantly prolonged in this group. Memis et al. [13] found that the onset of sensory and motor blockade in group A using dexmedetomidine in 0.5 μg/kg was decreased in comparison with the control group. In contrast with these results, Esmaoglu et al. [12] did not find any differences in the sensory and motor block onset and regression times between the two groups in their study. In our study, we observed that dexmedetomidine improved the quality of the anesthesia and decreased the postoperative analgesic requirements. This was in agreement with the study of Memis et al. [13] , which reported that the addition of 0.5 μg/kg dexmedetomidine to lignocaine for IVRA improved the quality of anesthesia and intraoperative-postoperative analgesia without causing side effects. Dexmedetomidine decreased the anesthetic requirements by up to 90%. It also significantly reduced rescue analgesic requirement compared with placebo in postoperative patients [14],[15] . This was in agreement with the study carried out by Kumar Alok et al., which showed that the addition of dexmedetomidine, at a dose of 1 μg/kg of body weight to lignocaine for IVRA, improved the quality of anesthesia and shortened the onset of sensory and motor blockades compared with placebo [16] . In our study, significantly prolonged sensory and motor recovery times were observed in group LD1 versus group L. Tourniquet pain is a major problem that emerges after the use of a pneumatic tourniquet during surgical procedures involving the upper or the lower limb; the mechanism of how tourniquet pain is elicited is still unclear [17] . In the current study, time of tolerance to first tourniquet pain was significantly prolonged in group LD2 versus groups L and LD1, whereas second tourniquet pain was prolonged in groups LD1 and LD2 versus group L. Memis et al. [13] found that tourniquet pain was attenuated by adding dexmedetomidine to lignocaine during IVRA. This was in accordance with the results obtained in the study carried out by Nasr and Waly [18] . Abrupt intravenous administration of 0.5-2 μg/kg dexmedetomidine resulted in moderate hypotension, bradycardia, and sedation [19] . In the study carried out by Memis et al. [13] , it was found that the addition of 0.5 ug/kg dexmedetomidine to lignocaine for IVRA enhanced the anesthetic and postoperative analgesic effect of lignocaine with cardiovascular stability during intraoperative and postoperative times. In contrast to these results, in the study carried out by Nasr and Waly [18] , bradycardia was detected in 35% of patients after release of tourniquet, which might be explained by the higher dose of dexmedetomidine, 1 μg/kg, used. In our current study, no major complications were encountered throughout the study period and no patient needed any intervention because of perioperative hemodynamic or respiratory problems. Minor LA side effects were the most prevalent adverse events after completion of the surgery and deflation of the upper arm tourniquet; two patients in group L, one patient in group LD1, and no patient in group LD2 experienced tinnitus, light headedness, headache, and circumoral numbness compared with patients in the forearm group. These side effects were transient and only required monitoring of the patients and reassurance. Gupta et al. [20] found that only a few incidences of side effects were encountered in our study such as mouth dryness, which was observed in 1 (3.3%) case in group A (dexmedetomidine 0.5 μg/kg) and 2 (6.7%) cases in group B (dexmedetomidine 1 μg/kg); bradycardia, tinnitus, and perioral numbness were noted in 3.3% of cases only in group B, which was in not in agreement with the study of Esmaoglu et al. [12] , who, at a dose of 1 μg/kg dexmedetomidine, did not observe any side effects such as hypotension or bradycardia that required treatment. Intravenous dexmedetomidine produces abrupt hypotension and bradycardia, resulting in a moderate decrease in both MAP and HR from baseline [21] . Its sedative, proanesthetic, and proanalgesic effects at 0.5-2 μg/kg with intravenous infusion arise mainly because of its ability to blunt the central sympathetic response. It also minimizes opioid-induced muscle rigidity, reduces postoperative shivering, exerts hemodynamic stabilizing effects, and causes minimal respiratory depression [22] . Jaakola assessed the safety and efficacy of intravenous dexmedetomidine as a premedication before IVRA. She found that 1 μg/kg of dexmedetomidine was an effective premedication before IVRA because it reduced patients' anxiety, sympathoadrenal responses, and opioid analgesic requirements, but it did not reduce tourniquet pain [23] . Memis et al. [13] concluded that dexmedetomidine 0.5 μg/kg and atropine administered as a premedication might have resulted in a lower degree of this side effect. However, no serious side effects were observed in our study, although we did not use atropine as a premedication. The same was observed by Esmaoglu et al. [12] even with the addition of 1 μg/kg dexmedetomidine to lignocaine without atropine as a premedication. No previous studies have shown the use of dexmedetomidine in the IVRA technique as a local additive versus systemic intarvenous administration. Mahmoud et al. found that supplementation of spinal anesthesia with intravenous dexmedetomidine produced longer sensory and motor block than spinal analgesia alone. Adverse effects were avoided by the slow infusion of dexmedetomidine. All patients achieved good sedation levels and resulted in better operating conditions for the surgeon, without significant respiratory depression [24] . Perioperative hemodynamic and respiratory monitoring showed no significant difference between the three groups [23],[25] . In conclusion, local addition of dexmedetomidine to IVRA produced shorter onset of sensory and motor blockades and slower recovery times of sensory and motor blockades versus systemic infusion of dexmedetomidine. The duration of postoperative analgesia, anesthetic conditions, operative conditions, number of patients requiring rescue intraoperative, amount of rescue intraoperative fentanyl, and tramadol consumption in the first 24 h postoperatively were comparable between both groups using dexmedetomidine either local or systemic use. Time of tolerance to first tourniquet was delayed and the sedation score was higher in the group using systemic rather than local addition of dexmedetomidine.
| Acknowledgements | | |
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]
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