Intraocular Pressure and Quality of Blockade in Peribulbar Anesthesia Using Ropivacaine or Lidocaine with Adrenaline: A Double-Blind Randomized Study

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1 Tohoku J. Exp. Med., 2004, Ropivacaine 204, in Peribulbar Block: a Comparison with Lidocaine 203 Intraocular Pressure and Quality of Blockade in Peribulbar Anesthesia Using Ropivacaine or Lidocaine with Adrenaline: A Double-Blind Randomized Study GONUL OLMEZ, SEVIN SOKER CAKMAK, 1 IHSAN CACA 1 and M. KAAN UNLU 1 Department of Anesthesiology and Reanimation, and 1 Department of Ophthalmology, Faculty of Medicine, Dicle University, Diyarbakir, Turkey OLMEZ, G., CAKMAK, S.S., CACA, I. and UNLU, M.K. Intraocular Pressure and Quality of Blockade in Peribulbar Anesthesia Using Ropivacaine or Lidocaine with Adrenaline: A Double-Blind Randomized Study. Tohoku J. Exp. Med., 2004, 204 (3), The aim of this study was to compare the effects of ropivacaine with those of lidocaine on the intraocular pressure (IOP) and the quality of the blockade in peribulbar anesthesia for cataract surgery. Fifty patients were allocated randomly into two groups and received 7-10 ml of 0.75% ropivacaine or 2% lidocaine with adrenaline, though the peribulbar two-point injection. The quality of the blockade was assessed by ocular and eyelid akinesia, pain during the peribulbar injection, and surgical satisfaction. The duration of the motor block was also evaluated after surgery. The IOP was measured using a Tonopen before the blockade (control) and at 1, 5, and 10 min after injection of the anesthetic. Lidocaine induced significantly lower akinesia scores at 6, 8, and 10 min post-injection than did ropivacaine. The mean IOP (mmhg) was significantly lower with respect to the baseline level at 10 min after blockade in the ropivacaine group compared with the lidocaine group. Ropivacaine also caused less pain on injection. There was no difference in surgical satisfaction between the groups. The duration of the motor block obtained with ropivacaine was longer than that obtained with lidocaine. Our data indicate that ropivacaine has efficacy similar to lidocaine, with slightly longer onset and duration of the motor blockade. In addition, ropivacaine (0.75%) induces lower IOP and less pain on injection than does lidocaine (2%) when used in peribulbar anesthesia for cataract surgery. lidocaine, ropivacaine, peribulbar anesthesia 2004 Tohoku University Medical Press Received June 21, 2004; revision accepted for publication September 8, Address for reprints: Sevin Soker Cakmak, M.D., Department of Ophthalmology, Dicle University Faculty of Medicine, TR-21280, Diyarbakir, Turkey. sokers@dicle.edu.tr 203

2 204 G. Olmez et al. Cataracts are a significant cause of disability among the elderly. Regional anesthesia is widely used during cataract extraction surgery because it avoids many of the complications associated with general anesthesia and allows the procedure to be performed as an outpatient surgery (Donlon 2000). Various local anesthetics are used for peribulbar anesthesia; however, there is no universally recommended agent. The use of mixtures of local anesthetics for regional anesthesia has recently become popular, based on the premise that rapid-acting agents with short duration of effect could compensate for the longer latencies associated with agents that have longer duration of effect. However, some studies have shown that there were no clinically significant advantages to the use of mixtures of local anesthetic agents (Berde and Strichartz 2000; Luchetti et al. 2000; Nicholson et al. 2000; Perello et al. 2000; Ozcan et al. 2003). In addition, using a single effective agent is preferable to an unnecessary polypharmacy approach. Ropivacaine is a long-acting local anesthetic used as a single agent in peribulbar anesthesia for cataract surgery (Nociti et al. 1999; Nicholson et al. 1999, 2000; Luchetti et al. 2000; Perello et al. 2000; Ozcan et al. 2003). Evidence suggests that ropivacaine has a higher threshold for cardiovascular and central nervous system toxicity than does bupivacaine and a lower threshold than does lidocaine (Arlock 1988; Feldman et al. 1989). In addition, the quality of the motor block, the duration of analgesia, and the pain of injection induced by ropivacaine used in peribulbar anesthesia were superior to those observed with other anesthetics (Luchetti et al. 2000; Ozcan et al. 2003). It has been shown that adrenaline does not increase the efficacy of ropivacaine owing to the inherent vasoconstrictive properties of ropivacaine (Cederholm et al. 1992). Lidocaine acts rapidly and produces anesthesia of moderate duration. The potential toxicity of lidocaine is lower than that of other local anesthetic agents. The duration of cataract surgery is relatively short, thus the moderate duration of li- docaine-induced blockade is not a disadvantage. Therefore, lidocaine is widely used as the sole anesthetic agent in cataract surgery (Thomson 1988; Davis and O Connor 1989; Mjahed et al. 1996; Bedi and Carabine 1999). It has been reported to have similar effects when used alone or in combination with bupivacaine for peribulbar anesthesia (Davis and O Connor 1989; Bedi and Carabine 1999). As there have been no previous studies directly comparing ropivacaine with lidocaine in peribulbar anesthesia, we compared the quality and duration of the blockade and the intraocular pressure produced by these two agents during peribulbar anesthesia. METHODS This study was undertaken in the Department of Ophthalmology at Dicle University following approval of the protocol by the institutional ethics committee. Fifty patients scheduled for extracapsular cataract extraction under local anesthesia were enrolled in the study after giving written informed consent. Patients with glaucoma were excluded from the study. The patients received no premedication. They were randomly assigned to two groups of 25 each according to the local anesthetic employed for the peribulbar anesthesia. The patients in the ropivacaine group (GR) received 0.75% ropivacaine, and those in the lidocaine group (GL) received 2% lidocaine combined with 1 : adrenaline. All patients were monitored throughout the procedure by pulse oxymetry, electrocardiography, and noninvasive blood pressure measurement. All local anesthetic solutions of were prepared immediately prior to the procedure by a nurse anesthetist who played no further role in the study. In all cases, peribulbar anesthesia was conducted by an experienced physician. A total volume of 7-10 ml of local anesthetic per patient was injected using a standardized, two-point, peribulbar injection technique with a 25-mm, 25-g needle; 4-6 ml of anesthetic was injected at

3 Ropivacaine in Peribulbar Block: a Comparison with Lidocaine 205 the junction of the lateral third with the medial two-thirds of the inferior orbital edge, through the eyelid, and the residual volume was injected in the upper internal edge of the eyeball, through the upper eyelid. Different volumes of local anesthetic were used depending on the degree of filling of the orbit observed during injection. Digital pressure was applied to the eye for 10 min between intermittent measurements, rather than using a mechanical device; digital pressure was preferrable to permit frequent measurement of IOP and akinesia scores. The post-block evaluations were performed by a second physician who was blinded to the local anesthetic used. The akinesia scores were obtained from assessment of movement in five muscles: the superior rectus, inferior rectus, medial rectus, lateral rectus, and levator palpabrae superior. Movement was scored from 0 (no movement) to 3 (full movement) in each muscle, giving a total score in the range 0 to 15. Ocular motility was assessed at 2, 4, 6, 8, and 10 min after injection. The IOP was measured four times using a Tonopen: before the injection of the anesthetic (control) and at 1, 5, and 10 min after injection. The patients indicated the level of pain experienced during the injection of the anesthetic solution using a visual analogue scale (VAS) ranging from 0 to 10 (0 = no pain, 10 = the worst pain possible). Surgical satisfaction was assessed by the surgeons as being poor, adequate, or good. After the surgery, the ocular muscle functions were assessed every 30 min for 5 h. The time at which full movement returned was accepted as the duration of motor block. Categorical samples were compared using the Chi-square test. The mean akinesia scores were compared between the groups using the independent t-test. The mean IOP levels were compared between the groups using the paired t-test. The VAS scores were compared using the Mann- Whitney s U-test. Surgical satisfaction was compared with the Fisher exact Chi-square test. The significance level was defined as p < RESULTS The patients in both groups had similar demographic characteristics (Table 1). There were significant differences in ocular motility between the two groups. Motor blockade was observable beginning at 2 min after injection in both groups. Lower akinesia scores were obtained in the lidocaine group at 6, 8, and 10 min after injection (Fig. 1) than in the ropivacaine group. The mean akinesia scores for the groups during the 10-min observation period are summarized in Table 2. There were no significant differences in the IOP levels between the two groups. The IOP level of the ropivacaine group at 10 min was significantly lower with respect to the baseline level (p = 0.029) (Table 3). The duration of the motor block was significantly longer in the ropivacaine group (p < 0.001) than in the lidocaine group; (294 ± 62 min and ± 53, respectively). The visual analogue pain scores are shown in Table 4. Lidocaine caused significantly more pain on injection than did ropivacaine (p < 0.05). Surgical comfort was satisfactory in both groups, TABLE 1. Patient characteristics. Ropivacaine (n = 25) (mean ± S.D.) Lidocaine (n = 25) (mean ± S.D.) p value Sex (male/female) 11/14 10/15 NS Side of operation; R/L 12/13 11/14 NS Age (year) 68.8 ± ± 6.7 NS Weight (kg) 76.4 ± ± 5.2 NS Duration of surgery (min) 49.9 ± ± 11 NS

4 206 G. Olmez et al. Fig. 1. The mean akinesia scores for the ropivacaine and lidocaine groups at the indicated times postinjection., Ropivacaine;, Lidocaine. TABLE 2. Mean akinesia scores of muscle groups during the first 10 min after peribulbar injection of anesthetic solution. (min) Ropivacaine Lidocaine p value ± ± ± ± ± ± ± ± ± ± TABLE 3. Mean IOP levels (mmhg) at the indicated times following peribulbar i n j e c t i o n o f ro p i v a c a i n e o r lidocaine. Ropivacaine Lidocaine p value * Preblock ± ± min ± ± min ± ± min ± 2.86 ** ± * Comparison of ropivacaine and lidocaine groups. ** Significantly lower than baseline (pre-block) level (p = 0.029). TABLE 4. Visual analogue pain scores immediately following injection of peribulbar anesthesia. Ropivacaine Lidocaine Median pain scores 2 5 Interquartile range TABLE 5. Surgical satisfaction levels in patients receiving either ropivacaine or lidocaine peribulbar anesthesia. Poor Adequate Good Ropivacaine Lidocaine

5 Ropivacaine in Peribulbar Block: a Comparison with Lidocaine 207 and there were no significant differences between the groups (p > 0.05; Table 5). None of the patients required additional local anesthetic solution during the procedure, and no drug-related adverse effects were observed in either group. DISCUSSION In addition to analgesia, the goal of ideal peribulbar anesthesia is to obtain complete akinesia of the eye globe and low intraocular pressure in order to provide optimal surgical conditions. In this study, the motor blockade began at 2 min after injection in both groups; it was significantly profound at 6, 8, and 10 min after injection with lidocaine anesthesia, as compared with ropivacaine. Sufficient motor block for surgery was achieved at 10 min in both groups and provided good operating conditions. Bedi et al. (1999) used 2% lidocaine with epinephrine for peribulbar anesthesia, and the time of onset of anesthesia adequate for surgery was similar to that obtained with prilocaine and lidocaine-bupivacaine mixtures. In a report by Davis et al. (1989), 2% lidocaine provided a successful block at 4 min after injection. In patients anesthetized with ropivacaine or lidocaine, there was an increase in the IOP during the first minute after injection. Peribulbar anesthesia itself can cause a transient increase in the IOP, secondary to the increase in orbital pressure owing to the injection of the local anesthetic solution. The IOP nevertheless returns rapidly to baseline values upon relaxation of the extraocular muscles, resulting in a decrease in the external pressure over the ocular globe (Donlon 2000). There were no significant differences in the IOP levels between the groups, even though the IOP was decreased significantly below baseline values at 10 min in the ropivacaine group. It has been reported that the vasoconstrictive effect of ropivacaine leads to a decrease in the intraocular blood volume and that this might play a role in the observed decrease in the IOP (Nakamura et al. 1993; Ishiyama et al. 1997; Nociti et al. 2001; Ozcan et al. 2003). In addition, the IOP might have been decreased in the ropivacaine group because the diffusion of ropivacaine through the tissues may be faster than that of lidocaine. In outpatient surgery, where premedication and sedation are best avoided, the lower pain scores associated with the injection of ropivacaine make it a more comfortable and acceptable technique for the patients. The lower pain scores may be attributable to the ph of the local anesthetic solution (Berde and Strichartz 2000). In a recent study comparing ropivacaine with bupivacainemepivacaine, a greater incidence of pain on injection was found in the bupivacaine-mepivacaine group (Luchetti et al. 2000). Other studies have reported that only prilocaine was less painful than lidocaine or a lidocaine-bupivacaine mixture when injected (Henderson and Franks 1996; Bedi and Carabine 1999). The assessment of the duration of motor block in this study indicated that, as expected, ropivacaine had a longer duration. Prolonged motor block and prolonged analgesia may be preferable in cataract surgery. Ozcan et al. (2003) reported that 0.75% ropivacaine resulted in lower post-operative pain scores than did a bupivacainelidocaine mixture. We conclude that 0.75% ropivacaine results in lower IOP and decreased pain during injection than does 2% lidocaine in peribulbar anesthesia. References Arlock, P. (1988) Actions of three local anaesthetics: lidocaine, bupivacaine and ropivacaine on guinea pig papillary muscle sodium channels (Vmax). Pharmacol. Toxicol., 63, Bedi, A. & Carabine, U. (1999) Peribulbar anaesthesia: a double-blind comparison of three local anaesthetic solutions. Anaesthesia, 54, Berde, C.B. & Strichartz, G.R. (2000) Local Anesthetics, In: Anesthesia, edited by R.D. Miller, 5th ed., Philadelphia, Churchill Livingstone, pp Cederholm, I., Evers, H. & Lofstrom, J.B. (1992) Skin blood flow after intradermal injection of ropivacaine in various concentrations with and without epinephrine evaluated by laser Doppler flowmetry. Reg Anesth., 17,

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