European Journal of Cardiovascular Medicine

Intravenous regional anaesthesia (IVRA) is a form of regional anaesthesia. The flow of blood is prevented by a proximally applied tourniquet thus isolating the limb from systemic circulation[1]. The administration of IVRA requires venipuncture, application of two tourniquets and local anaesthetics [2]. IVRA has been limited by tourniquet pain and the inability to provide postoperative analgesia [3]. Adjuvants are drugs that increase the efficacy or potency of other drugs when given concurrently [4]. To improve the quality of IVRA and postoperative analgesia, the addition of various drugs to local anaesthetics (Lignocaine) was investigated [5]. Dexmedetomidine, an imidazole compound, is the pharmacologically active dextroisomer of medetomidine. It is a potent alpha-2-adrenoceptor agonist with eight times higher affinity for alpha2–adrenoceptor than clonidine, shown to improve the quality of anesthesia, reduce tourniquet pain and post- operative analgesic requirement [6,7]. Various studies have shown that small doses of intravenous dexmedetomidine can enhance sensory and motor block with few side effects [8].The present study aimed to evaluate the efficacy of dexmedetomidine (1mcg/kg) as an adjuvant to lignocaine (3mg/kg) for Intravenous regional anaesthesia.

50 ASA I & II patients between in age group 21-60 years posted for elective forearm and hand surgeries attending at Kurnool Government General Hospital, Kurnool was selected. The patients were divided into 2 groups of 25 in each group.

Group-I: Lignocaine (3mg/kg) with a concentration of 0.5% dissolved in normal saline.

Group-II: Dexmedetomidine (1mcg/kg) with (3mg/kg) Lignocaine with a concentration of 0.5% dissolved normal saline

Inclusion criteria:

• ASA grade I or II
• Age group 21-60yrs
• Patients posted for elective forearm and hand surgeries

Exclusion criteria:

• ASA grade III and above.
• Patient’s refusal.
• Allergy to study drugs.
• Patients taking other sedative drugs.
• Pregnant patients.
• Patients with history of any cardiac, pulmonary, liver, neuro-psychiatric diseases.
• Patients with history of any coagulation disorders, Raynaud’s disease, Paget’s disease, Sickle cell anemia, compartment syndrome.

Methodology

After a thorough clinical examination and relevant laboratory investigations of all patients, an informed, valid, written consent was obtained, both for the conduct of the study as well as for the administration of GA. All patients were kept nil by mouth for 8 hours before surgery. Tablet ranitidine (150mg) was administered orally at 6 am on the day of surgery.

Anaesthetic Procedure

All the patients were re-examined, assessed and weighed pre-operatively on the day of surgery. Drugs including emergency drugs were kept ready. Also monitoring equipment like pulse oximeter, non-invasive blood pressure, and ECG monitors were checked and applied to each patient on arrival to the operating room. An intravenous cannula of 18G was secured on the non-operative limb for infusion of intravenous fluids and drug administration and the patient’s baseline vital data (HR, Spo2, ECG & NIBP) were recorded.

Technique of IVRA:

An intravenous cannula of 22G was inserted in the operative hand as distal as possible. A double tourniquet was positioned on the operative arm. The operative extremity was exsanguinated by elevation and wrapping it with a 10cm Esmarch bandage. The proximal tourniquet was inflated by 100mm Hg more than systolic BP to a minimum of 250 mmHg and the Esmarch bandage was removed. Circulatory isolation of the operative arm was confirmed by inspection of the hand and by the absence of the radial pulse. The Bier’s block was achieved by using (3mg/kg) lignocaine diluted with saline to a Concentration of 0.5% in the Group-I and dexmedetomidine (1mcg/kg) with (3 mg/kg) Lignocaine diluted with saline to a concentration of 0.5% in the Group-II. IVRA solution was administered slowly through an IV cannula over 3 minutes. After sensory and motor blocks were achieved, the distal tourniquet was inflated to 250 mmHg, the proximal tourniquet was released, i.v. cannula from the operative hand was removed and the patient was handed over to surgeons. At the end of the surgery, the tourniquet was deflated by cyclic deflation technique, and the tourniquet deflation time should not be less than 1hr after injecting IVRA. The parameters like HR, SBP, DBP, the onset of sensory block, the onset of motor block, regression of sensory block, regression of motor block, and duration of postoperative analgesia (Assessment of postoperative analgesia was done by using Visual Analogue Score (VAS) score. The total duration of analgesia was monitored for up to 4 hours post-operatively using a Visual Analogue Score. It is the standard tool for rating pain using a 0-10 scale (0= no pain, 10= worst possible pain) and the time of 1st rescue analgesia) was noted and recorded.

We observed the age distribution of patients with an incidence of 12(48%)in 21-30 age group, 4(16%) in 31-40 age group,4(16%)in 41-50 age group,5(20)in 51-60 age group of Group-I(Lignocaine-3mg) patients and 18(72%) in 21-30 age group, 3(18%)in 31-40 age group, 2(8%)in 41-50 age group, 2(8%) in 51-60 age group of Group-II (Dexmedetomidine -1mcg/kg with 3mg/kg Lignocaine) patients in our study [Table 1].The meantime for onset of sensory block was 3.61±0.92 minutes in Group-I patients compared to Group-II patients(1.94±1.13 minutes); the meantime for onset of motor block was 5.69 ±1.29 minutes in Group-I patients compared to Group-II patients (3.84 ±1.49 minutes); The mean time for regression of sensory block was 4.24 ±0.82 minutes in Group-I patients  compared to Group- II patients (6.47±1.43minutes);The mean time for regression of motor block was 3.92±1.51 minutes in Group-I patients compared to Group-II patients(5.78±1.33minutes) was observed. In Group-I patients, the mean time for post-operative analgesia was 25.10+6.56 minutes. Compared to Group-II patients (234+40.42 minutes) was noted in the present study [Table 2]. The hemodynamic parameters like Intraoperative Systolic Blood Pressure, Intraoperative Diastolic Blood Pressure, Intraoperative mean Heart rate, and Post-operative mean Systolic Blood Pressure, Post-operative mean Diastolic Blood Pressure, Post-operative mean Heart rate were recorded in Group-I (Lignocaine-3mg) patients and Group-II (Dexmedetomidine -1mcg/kg with 3mg/kg Lignocaine) patients in the present study [Table 3]. We have not observed patients with respiratory depression, oral tingling, dizziness or any other complications in our study.

The present study demonstrated that the addition of dexmedetomidine, in a dose of 1 mcg/ kg of body weight, to lignocaine for IVRA not only improved postoperative analgesia without causing significant side effects but also shortened the onset of sensory and motor block as compared to lignocaine alone. Recent studies have shown that the addition of clonidine [9] can improve the efficacy of lignocaine for intravenous regional anaesthesia in decreasing the onset of severe tourniquet pain [10,11]. The mean time for onset of sensory block was 3.61±0.92 minutes in Group-I patients compared to Group-II patients (1.94±1.13 minutes); the meantime for onset of motor block was 5.69 ±1.29 minutes in Group-I patients compared to Group-II patients (3.84 ±1.49 minutes) showed statistically significant in comparison of both the groups suggests that addition of dexmedetomidine (1mcg/kg) hastens the onset of sensory and motor block. The addition of dexmedetomidine (1mcg/kg) as adjuvant to lignocaine in study group compared with plain lignocaine for IVRA showed the onset of sensory block was significantly faster in group receiving dexmedetomidine as adjuvant in comparison with the control group and the dexmedetomidine (0.5mcg/kg) as an adjuvant to lignocaine in the study group compared with plain lignocaine for IVRA showed the onset of motor block was significantly faster in the group receiving dexmedetomidine as an adjuvant in comparison with control group[12,13]. Our results are in agreement with previous literature. The mean time for regression of sensory block was 4.24 ±0.82 minutes in Group-I patients compared to Group-II patients (6.47±1.43minutes); The mean time for regression of motor block was 3.92±1.51 minutes in Group-I patients compared to Group-II patients (5.78±1.33minutes) was observed suggests that the addition of dexmedetomidine (1mcg/kg) to (3mg/kg) lignocaine delays the time to regression of sensory and motor block with high significance in our study. Intravenous dexmedetomidine as premedication before giving IVRA in hand surgeries and also suggested that dexmedetomidine is an effective premedication for IVRA. The dexmedetomidine (1mcg/kg) as adjuvant to lignocaine in the study group compared to plain lignocaine for IVRA showed the regression of sensory and motor block was slower in the group receiving dexmedetomidine as adjuvant in comparison with the control group with statistically significant[12,13,14]. In Group-I patients, the mean time for postoperative analgesia was 25.10+6.56 minutes compared to Group-II patients (234+40.42 minutes) was noted. The difference in duration of postoperative analgesia was statistically significant showing that the addition of dexmedetomidine (1mcg/kg) prolongs postoperative analgesia in the present study [15]. The efficacy of dexamethasone (8mg) with lignocaine (3mg/kg) in one group and plain lignocaine (3mg/kg) and plain lignocaine (3mg/kg) and intravenous dexamethasone (8mg) and concluded that the addition of 8 mg dexamethasone to lidocaine for IVRA in patients undergoing hand surgery improves postoperative analgesia during the first postoperative day. The quality of anaesthesia was significantly better and sedation was less in the dexmedetomidine than in the clonidine group [16].The time to the first analgesic requirement was significantly longer in the dexmedetomidine group after the tourniquet release as compared to Ketamine and control group [17]. In the present study, a fall in systolic blood pressure was observed in two patients (Group II) after the release of the tourniquet may be due to the entry of blood into the operative limb after the release of the tourniquet leading to a fall in blood pressure but the changes were statistically insignificant. Acute dexmedetomidine intravenous administration produces abrupt hypertension and bradycardia until the central sympatholytic effects dominate resulting in a moderate decrease in both Mean arterial pressure (MAP) and HR from baseline and it also has a sedative effect. The hemodynamic changes were not observed with the use of dexmedetomidine in IVRA [12,17,18]. The results of our study are similar to previous studies and acknowledge the significant efficacy of dexmedetomidine as an adjuvant to Lignocaine in Intravenous regional anaesthesia.

The addition of dexmedetomidine as an adjuvant to Lignocaine can be used safely for early onset and delayed regression of motor and sensory block with prolonged post- operative analgesic effect with the minimal side effects and good hemodynamics stability was observed in our study.

Acknowledgement:                                                                                                                                      

The authors are also grateful to authors, editors and publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.

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