Does Dexamethasone Improve the Quality of Intravenous Regional Anesthesia and Analgesia? A Randomized, Controlled Clinical Study

Abstract

We investigated the anesthetic and analgesic effectiveness of adding dexamethasone to lidocaine for IV regional anesthesia (IVRA). Seventy-five patients undergoing ambulatory hand surgery were randomly assigned to one of three groups: group L received 3 mg/kg lidocaine, group LD received 3 mg/kg lidocaine + 8 mg dexamethasone, and group LDc received 3 mg/kg lidocaine for IVRA and 8 mg dexamethasone IV to the nonsurgical arm. IVRA was established using 40 mL of a solution. Visual analog scale and verbal pain scores were recorded intraoperatively and for 2 h postoperatively. Postoperative pain was treated with oral acetaminophen 500 mg every 4 h when visual analog scale score was more than 3. Time to request for the first analgesic and the total dose in the first 24 h were noted. Times to onset of complete sensory and motor block were similar in the 3 groups. The times to recovery of motor block (L = 8 [5.91–10.08] min, LD = 13 [6.76–20.19] min, LDc = 6 [4.44–8.43] min) and sensory block (L = 7 [5.21–10.30] min, LD = 12 [6.11–19.40] min and LDc = 6 [4.2–8.11] min) were longer in group LD (P < 0.05). Patients in group LD reported significantly lower pain scores and required less acetaminophen in the first 24 h after surgery. In conclusion, the addition of 8 mg dexamethasone to lidocaine for IVRA in patients undergoing hand surgery improves postoperative analgesia during the first postoperative day.

In Brief

IMPLICATIONS: The study was designed to evaluate the effect of dexamethasone when added to lidocaine for IV regional anesthesia. The addition of 8 mg dexamethasone to lidocaine for IV regional anesthesia improves the quality of anesthesia and both intraoperative and postoperative analgesia.

IV regional anesthesia (IVRA) is a safe, simple to administer, and effective method of providing anesthesia for hand surgery expected to last less than 1 h, but it does not provide effective tourniquet tolerance and postoperative analgesia after tourniquet release. A variety of drugs have been added as adjuncts to local anesthetics for IVRA, including opioids, clonidine, nonsteroidal antiinflammatory drugs, dexmedetomidine, and neostigmine, in attempts to improve intraoperative anesthesia and postoperative analgesia (^1,2).

Acute inflammation induced by tissue injury plays a significant role in the genesis of surgical pain, and dexamethasone should theoretically be beneficial in the management of acute surgical pain as a result of its potent antiinflammatory effect (³). It has been reported that bupivacaine combined with dexamethasone prolongs the duration of analgesia in nerve blocks (^4–6).

There is no study assessing the analgesic effects and duration of analgesia of dexamethasone as an adjunct to local anesthetics for IVRA procedures. The purpose of this study was to evaluate the anesthetic and analgesic effectiveness of dexamethasone administered in addition to lidocaine in IVRA for ambulatory hand surgery.

Methods

After obtaining approval of the local ethics committee and securing informed patient consent we recruited 75 ASA physical status I–II patients, aged between 20– 50 yr, who were undergoing elective carpal tunnel release surgery. The patients were randomly allocated to 1 of 3 groups; each group consisted of 25 patients. Randomization was performed using a closed envelope method.

Patients with Reynaud’s disease, scleroderma, sickle cell anemia, myasthenia gravis, decompensated cardiac disease, diabetes mellitus, peptic ulcer, gastritis, and those with liver or renal insufficiency were excluded.

After establishing noninvasive arterial blood pressure, electrocardiogram, and peripheral oxygen saturation monitoring (Drager Cicero EM, Medizinteckhnik GmbH Lübeck, Germany) 2 venous cannulae were inserted: 1 in a vein on the dorsum of the operative hand (22-gauge) and the other in the opposite hand for crystalloid infusion. An IV infusion of 0.9% NaCl 5 mL · kg⁻¹ · h⁻¹ was started and 2 mg midazolam was given IV for premedication. The operative arm was elevated for 2 min and using an Esmarch bandage the venous capacitance of the arm was emptied. Then a double-pneumatic tourniquet was applied and the proximal tourniquet was inflated to a pressure of 250 mm Hg. After the Esmarch bandage was released patients in group L (n = 25) received 2% lidocaine (Jetokain Simplex; Adeka, Samsun, Turkey) 3 mg/kg (maximum, 200 mg) for IVRA and 2 mL NaCl 0.9% IV in the nonsurgical arm, patients in group LD (n = 25) received 2% lidocaine 3 mg/kg (maximum, 200 mg) plus 8 mg dexamethasone (Dekort, Deva, Istanbul, Turkey) for IVRA and 2 mL NaCl 0.9% IV in the nonsurgical arm, and those in group LDc (n = 25) received 2% lidocaine 3 mg/kg (maximum, 200 mg) for IVRA and 8 mg (2 mL) dexamethasone IV in the nonsurgical arm. In all groups 0.9% NaCl was added for a total volume of 40 mL. The IVRA solution was administered at a rate of 0.5 mL/s by an anesthesiologist who was blinded as to the drug being administered. After anesthesia was obtained the distal tourniquet was inflated to 250 mm Hg pressure, and the proximal tourniquet was deflated. The times for tourniquet and drug administration were recorded. After administration of drug, motor and sensory block were assessed every minute.

Motor function was assessed by asking the subject to flex and extend the wrist and fingers; complete motor block was noted when no voluntary movement was possible. Sensory block was assessed by a pinprick test performed with a 22-gauge short-beveled needle every 30 s. Patient response was evaluated in the dermatomal sensory distribution of the medial and lateral antebrachial cutaneous, ulnar, median, and radial nerves. Sensory block onset time was noted as the time from injection of study drug until sensory block in all dermatomes, and motor block onset time was the time elapsed from injection of study drug to complete motor block.

The tourniquet was not deflated before 30 min and was not inflated for more than 1.5 h. At the end of surgery, tourniquet deflation was performed using the cyclic deflation technique. Sensory recovery time (time elapsed after tourniquet deflation to recovery of pain in all dermatomes determined by pinprick test) was noted. Motor block recovery time (the time after tourniquet deflation to movement of fingers) was noted.

Arterial blood pressure, heart rate, and peripheral oxygen saturation were recorded preoperatively, after inflation of the tourniquet and every 5 min after administration of drug and after transfer to the recovery room at 5, 10, 15, 30, 60, and 120 min. During the operation tourniquet pain and after surgery pain at the operative site were assessed by visual analog scale (VAS) (0 cm = “no pain” and 10 cm = “worst pain imaginable”) and a verbal pain score (VPS) (0 = “no pain,” 1 = “light pain,” 2 = “moderate pain,” 3 = “severe pain,” 4 = “most severe pain”). For supplemental analgesia intraoperatively 0.05 mg fentanyl and postoperatively 500 mg acetaminophen were used when VAS was ≥3 and VPS was ≥2. Time to first request of analgesic was recorded. Patients were telephoned 24 h after surgery, and a resident not involved in the study asked about pain after discharge from hospital and amount of acetaminophen consumed. The total analgesic consumption during 24 h was recorded. The patients were questioned about complications such as allergic reaction, nausea, vomiting, tinnitus, cooling, tremor, arrhythmia, and metallic taste.

The statistical evaluation was done by SPSS 10.0 for Windows (SPSS Inc., Chicago, IL). To have a clinically significant effect, we estimated that use of dexamethasone should reduce the pain scores and analgesic requirement by 15% during the operation and the postoperative period compared with lidocaine. Therefore we calculated a sample size that would permit a type I error of α = 0.05 and power of 80%. We considered enrollment of 25 patients in each group would be enough. Data are expressed as the mean ± sd unless otherwise stated. Nominal data were analyzed using the χ² test and 2-way analysis of variance was used for analyzing changes seen in VAS and VPS according to time. Sensory and motor block progression and resolution were compared among the three treatment groups using the Kruskal-Wallis test and Bonferroni correction was used for VAS and VPS. Significance was accepted at P < 0.05.

Results

Patient characteristics, tourniquet time, and operation time were similar among the groups (Table 1).

Table 1: Patient Characteristics, Tourniquet and Operation Duration

The onset times of sensory and motor blocks were similar among the three groups (Table 2).

Table 2: Motor and Sensory Block Details

After tourniquet deflation the duration of sensory block and motor blocks were longer in group LD than in group LDc but these did not differ from those in group L (Table 2). During the operation the use of fentanyl for tourniquet pain was similar among the groups (4 patients in each group).

Time to first analgesic requirements postoperatively was shorter in group LD and statistically significantly different from group L and group LDc (Table 3). The mean analgesic consumption was less in group LD than in group L but not significantly different from group LDc (Table 3). On the first postoperative day 9 (36%) patients in group LD, 18 (72%) patients in group L, and 15 (60%) patients in group LDc used acetaminophen.

Table 3: Analgesic Requirements

The number of patients requesting analgesics was less in group LD; this result was statistically significant compared with group L (P = 0.033) (Table 3).

The VAS and VPS data are shown in Figs. 1 and 2. During and after the operation VAS and VPS were lower in group LD. There were statistically significant differences in the VAS, but not in VPS, between group LD and the other groups.

Figure 1.: Visual analog scale (VAS) values of the groups. TI, tourniquet inflation; ATD, after tourniquet deflation; Group L = lidocaine 3 mg/kg; Group LD = lidocaine 3 mg/kg plus 8 mg dexamethasone; Group LDc = lidocaine 3 mg/kg for intravenous regional anesthesia and 8 mg dexamethasone to the nonsurgical arm. ¶ P < 0.05 between Group LD- LDc; * P < 0.05 between Group LD-L.

Figure 2.: Verbal pain scale (VPS) values of the groups. TI, tourniquet inflation; ATD, after tourniquet deflation; Group L = lidocaine 3 mg/kg; Group LD = lidocaine 3 mg/kg plus 8 mg dexamethasone; Group LDc = lidocaine 3 mg/kg for intravenous regional anesthesia and 8 mg dexamethasone to the nonsurgical arm.

Discussion

These findings demonstrate that the addition of 8 mg dexamethasone to lidocaine for IVRA prolonged the sensory and motor block recovery times after the tourniquet release and improved the quality of anesthesia while decreasing postoperative analgesic requirements.

IVRA is a preferred technique for regional anesthesia for upper extremity surgery because of its effective and easy application and rapid onset time of anesthetic effect (^7,8). Inability to provide effective postoperative analgesia and tourniquet pain are the major disadvantages of IVRA (⁹). Lidocaine 0.5%–1% is one of the commonly used local anesthetic for IVRA (^10,11).

Tourniquet pain, which is described as a dull and aching pain sensation, is another well known limitation of IVRA. Skin compression (¹²), tourniquet size (¹³), inflation pressure (¹⁴), and adjuvants in the local anesthetic solution (¹⁵) have been implicated as factors involved in tourniquet pain. The incidence and intensity of tourniquet pain and associated hypertension have also been shown to be correlated with tourniquet time (¹⁶). In a recent prospective study (¹⁷), it is reported that <15% of patients at 30 min but more than 50% of patients at 70 min complained of tourniquet pain. In our study, the relatively short operative times and small values of intraoperative VAS and VPS make it difficult to draw conclusions about the possible effects of dexamethasone on tourniquet pain. These factors may also explain the discrepancy between statistical analysis of the VPS and VAS. Nevertheless, in group LD, intraoperatively VAS remained statistically significantly lower compared with other groups, showing better tourniquet pain control. Tourniquet pain is thought to be mediated by impulse propagation via small, unmyelinated, slow-conducting C fibers (¹⁸). The local application of corticosteroids also appears to mainly block transmission in the nonmyelinated C fibers (¹⁹). A study with longer tourniquet inflation times might have documented the more reliable analgesic effect of dexamethasone intraoperatively.

Many studies have shown that local steroid application can have an analgesic effect, although the results are not consistent. There is little information about functional and structural effects of corticosteroids on normal peripheral nerve fibers (^19–21). Acute inflammation from tissue injury has an important role in the formation of surgical pain, and dexamethasone may be useful for its antiinflammatory effect (³). Its analgesic effect has been proven previously (^3,22–27).

In our study, adding dexamethasone to lidocaine for IVRA did not affect the time to onset of either sensory or motor block. After tourniquet release, however, motor and sensory block recovery times were longer in group LD compared with the other groups. There are some studies reporting that dexamethasone has prolonged the duration of analgesia by local anesthetics (^4–6,28).

Although there was prolonged sensory and motor blockade, time to request for first analgesic was significantly shorter in group LD than the other groups but total analgesic requirement for the first 24 hours was significantly less in group LD. In our study, one might have expected a longer time to first analgesic requirement in group LD, but adding dexamethasone to lidocaine solution significantly shortened the first analgesic requirement time. This might be explained by the local irritation effect of adding dexamethasone. There were no clinical signs of local irritation and no patient complained of local irritation at the injection site in the two groups that received dexamethasone, and there is no report of local irritant effects of dexamethasone at the injection site in the literature.

In our study we observed that adding 8 mg dexamethasone to an IVRA solution provides better postoperative analgesia. In the local dexamethasone group the mean analgesic consumption and the number of patients requesting analgesics were significantly less when compared to the lidocaine-only group.

We found no study concerning usage of dexamethasone in IVRA from 1976 to the present. This is probably the first clinical study demonstrating the addition of 8 mg dexamethasone to lidocaine for IVRA. Dexamethasone did not shorten motor and sensory block onset time but prolonged motor and sensory block recovery time. Moreover, dexamethasone reduced postoperative analgesic consumption.

In conclusion, this study demonstrated that the addition of 8 mg dexamethasone to lidocaine in IVRA provided a significant decrease in intraoperative and postoperative VAS and therefore decreased postoperative analgesic consumption.

Thanks to Prof. Osman Saka and Ozgur Tosun for their help with statistical analysis.