University Department of Anaesthesia, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK Present addresses: 1 Department of Anaesthesia, John Radcliffe Hospital, Oxford OX3 9DU, UK. 2 Department of Anaesthesia, Frimley Park Hospital, Camberley GU16 7UJ, UK
* Corresponding author. E-mail: j.a.w.wildsmith{at}dundee.ac.uk
Accepted for publication September 9, 2004.
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Abstract |
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Methods. Forty ASA grade III patients undergoing elective perineal surgery under spinal anaesthesia were randomized to receive 3 ml ropivacaine 5 mg ml1, either in plain solution or with glucose 50 mg ml1. The extent and duration of sensory and motor block, pulse rate, blood pressure, and time to mobilization were recorded.
Results. Two patients (one per group) were withdrawn because of total block failure. There were significant differences in median time to onset of sensory block at T10 (plain 10 min; hyperbaric 5 min; P<0.01), median maximum extent (plain T8; hyperbaric T4; P<0.05), and median duration of sensory block at T10 (plain 25 min; hyperbaric 115 min; P<0.001). However, median times to complete regression of both sensory (270 vs 240 min; P<0.05) and motor (180 vs 120 min; P<0.001) block were longer in the plain group. Patients therefore mobilized sooner in the hyperbaric group (218 [n=16] vs 286 min [n=17]; P<0.01). All the hyperbaric blocks were adequate for surgery, but three patients receiving plain ropivacaine required general anaesthesia.
Conclusion. Addition of glucose 50 mg ml1 to ropivacaine 5 mg ml1 increases the speed of onset, block reliability, duration of useful block for perineal surgery, and speed of recovery. Plain solutions are less reliable for surgery above a dermatomal level of L1.
Keywords: anaesthetics local, ropivacaine ; anaesthetic techniques, subarachnoid
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Introduction |
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Methods |
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Lumbar puncture was performed with a 25-swg Whitacre needle using a midline approach at the second or third lumbar interspace with the patient in the left lateral position. The patients were randomized (shuffled, then numbered, opaque envelopes) to receive 3 ml ropivacaine 5 mg ml1 (15 mg) injected over 1015 s in either plain solution or with glucose 50 mg ml1. The solution was prepared aseptically by the anaesthetist administering the block, immediately before injection, by mixing ropivacaine 10 mg ml1 with an equal volume of either glucose 100 mg ml1 or sodium chloride 9 mg ml1 to give solutions with densities (at 37°C) of 1.01949 and 0.99953 g ml1 respectively.10 The patient was turned supine immediately at the end of injection, the time of which was defined as zero.
Thereafter an investigator, blinded to the solution administered, assessed the upper and lower extent of sensory block (analgesia to pinprick with the short bevel end of a 27-swg dental needle: caudal limit of sensory block assessment, S2), and the degree of motor block (modified Bromage scale: 0=full leg movement; 1=inability to raise extended leg, can bend knee; 2=inability to bend knee, can flex ankle; 3=no movement) and recorded the pulse rate and blood pressure 2, 5, 10, 15, 20, 25, and 30 min after injection. The patients were then transferred to the operating room and, if they wished, received sedation with a target-controlled infusion of propofol titrated to maintain verbal contact throughout. Because of this, and to avoid any interference, assessments were not made during surgery, but were continued at 30 min intervals thereafter until the block had regressed completely. I.V. fluid was administered only to replace operative blood loss, hypotension (>30% decrease in systolic pressure from baseline) being treated with i.v. ephedrine 6 mg.
Once sensory block had regressed fully, patients were encouraged to mobilize under supervision. Bladder catheterization was performed when surgically indicated, but time to micturition was recorded in all other patients. Patients were visited or telephoned 24 h and 37 days later to identify any sequelae.
Statistical analysis
The sample size was chosen to show a difference in extent of sensory block of 2 dermatomes (SD 1 dermatome) between the groups, based on an risk of 0.05 and a ß risk of 0.10, using data from a previous study.8 Data are presented as median [range], mean (SD) or frequencies as appropriate. Block characteristics were compared using the two-tailed MannWhitney U-test. A P value of <0.05 was considered statistically significant. Data were analysed using a standard computer based statistics package (Number Cruncher Statistical Systems [version 2001], Cork, Ireland).
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Results |
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Discussion |
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This study provides further evidence that hyperbaric ropivacaine, in a dose of 15 mg, produces predictable and reliable spinal anaesthesia for a variety of surgical procedures of relatively short duration. Duration of surgery was longer in the patients in this study, who received the plain solution, but two of the three blocks that were inadequate for surgery were related to inadequate spread, rather than regression before surgery ended. Even then, the regression was from a fairly low initial level (Fig. 1). Two previous studies of our own, using 3 ml ropivacaine 5 mg ml1 in either glucose 10 mg ml1 or glucose 50 mg ml1, produced a block that was predictable, and adequate for surgery in all patients.8 9 Similar findings have also been obtained by others using somewhat different protocols (e.g. larger doses) for spinal anaesthesia for Caesarean section.13 14 One study compared plain and hyperbaric solutions of ropivacaine, and the other hyperbaric solutions of ropivacaine and bupivacaine, but in both studies hyperbaric ropivacaine provided adequate spinal block for the procedure. In the comparison of the different solutions of ropivacaine, the hyperbaric preparation produced a higher, more consistent block with faster onset and recovery, whereas there was a failure rate with the plain solution,13 something noted by others also.1 2 5
While the addition of glucose to a local anaesthetic solution improves predictability, all users of spinal anaesthesia must be aware that considerable variation in both total spread and duration of action still occurs. Figure 2 shows the differences between the two groups by plotting median spread against time, but it is important to recognize that there is, at every time interval, a similar degree of variation to that shown for maximum observed spread in Figure 1. For the clinician, the key data are not so much the figures for average spread and duration, but their minima and maxima. Minimum figures for spread and duration indicate the guaranteed clinical utility of a particular technique. The maximum spread figure indicates the likelihood of complications such as hypotension, and that for maximum duration the potential need for close observation. While variability in spread can be minimized by adding glucose, the variation in duration is very much a patient-specific factor. The average duration can be influenced by drug and dose choices, but the variability remains. This variability is even evident between studies. In a previous study the median duration of 15 mg ropivacaine 5 mg ml1 (with glucose 50 mg ml1) at T10 was 56 [range 28145] min, whereas it was 115 [50180] in our study.
Although this study was not performed in the day-case setting, the suitability of hyperbaric ropivacaine for ambulatory surgery should be considered. McDonald and colleagues, using sub-clinical doses of ropivacaine in volunteers, concluded that it was less potent than bupivacaine and offered no advantage for use in outpatient anaesthesia. However, what they found was that ropivacaine produced sensory block of similar onset and extent as bupivacaine, but that it was associated with less motor block and faster regression of both sensory and motor block, findings similar to those reported here.15 Subsequently, clinically relevant doses of hyperbaric ropivacaine have been shown, as in this study, to provide predictable and reliable anaesthesia for elective surgery, albeit of a shorter duration than equal doses of bupivacaine.9 The standard agent for short duration spinal anaesthesia has been lidocaine, but continuing concerns about the high incidence of transient neurological symptoms limit its use.1617
In summary, hyperbaric ropivacaine produced more predictable and reliable sensory and motor block, with faster onset, than a plain solution. In addition, although the duration of useful block for surgery was increased, so was the speed of recovery from both sensory and motor block. Patients therefore mobilized more quickly after spinal anaesthesia with hyperbaric ropivacaine, something that may be particularly useful for ambulatory surgery and any operation when a long duration of block is unnecessary or undesirable, although it should be noted that the drug is unlicensed for this indication at present. Plain solutions of ropivacaine are associated with a less favourable pattern of block such that we advocate that they should not be used for surgery at or above the dermatomal level of the inguinal ligament, that is L1.
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Acknowledgments |
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Footnotes |
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References |
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2 Wahedi W, Nolte H, Klein P. Ropivacaine for spinal anesthesia. A dose-finding study. Anaesthetist 1996; 45: 73744[CrossRef][ISI][Medline]
3 Gautier PE, De Kock M, Van Steenberge A, et al. Intrathecal ropivacaine for ambulatory surgery. Anesthesiology 1999; 91: 123945[ISI][Medline]
4 McNamee DA, Parks L, McClelland AM, et al. Intrathecal ropivacaine for total hip arthroplasty: double-blind comparative study with isobaric 7.5 mg.ml1 and 10 mg.ml1 solutions. Br J Anaesth 2001; 87: 7437
5 McNamee DA, McClelland AM, Scott S, Milligan KR, Westman L, Gustafsson U. Spinal anaesthesia: comparison of plain ropivacaine 5 mg.ml1 with bupivacaine 5 mg.ml1 for major orthopaedic surgery. Br J Anaesth 2002; 89: 7026
6 Logan MR, McClure JH, Wildsmith JAW. Plain bupivacaine: an unpredictable spinal anaesthetic agent. Br J Anaesth 1986; 58: 2926[Abstract]
7 Lee A, Ray D, Littlewood DG, Wildsmith JAW. Effect of dextrose concentration on the intrathecal spread of amethocaine. Br J Anaesth 1988; 61: 1358[Abstract]
8 Whiteside JB, Burke D, Wildsmith JAW. Spinal anaesthesia with ropivacaine 5 mg.ml1 in glucose 10 mg.ml1 or 50 mg.ml1. Br J Anaesth 2001; 86: 2414
9 Whiteside JB, Burke D, Wildsmith JAW. Comparison of ropivacaine 0.5% (in glucose 5%) with bupivacaine 0.5% (in glucose 8%) for spinal anaesthesia for elective surgery. Br J Anaesth 2003; 90: 3048
10 McLeod GA. Density of spinal anaesthetic solutions of bupivacaine, levobupivacaine and ropivacaine with and without dextrose. Br J Anaesth 2004; 92: 54751
11 Chambers WA, Edstrom HH, Scott DB. Effect of baricity on spinal anaesthesia with bupivacaine. Br J Anaesth 1981; 53: 27982[Abstract]
12 Hocking G, Wildsmith JAW. Intrathecal drug spread. Br J Anaesth 2004; 93: 56878
13 Khaw KS, Ngan Kee WD, Wong M, Ng F, Lee A. Spinal ropivacaine for Cesarean delivery: a comparison of hyperbaric and plain solutions. Anesth Analg 2002; 94: 6805
14 Chung CJ, Choi SR, Yeo KH, Park HS, Lee SI, Chin YJ. Hyperbaric spinal ropivacaine for Cesarean delivery: a comparison to hyperbaric bupivacaine. Anesth Analg 2001; 93: 15761
15 McDonald SB, Liu SS, Kopacz DJ, Stephenson CA. Hyperbaric spinal ropivacaine: a comparison to bupivacaine in volunteers. Anesthesiology 1999; 90: 9717[ISI][Medline]
16 Breebaart MB, Vercauteren MP, Hoffmann VL, Adriaensen HA. Urinary bladder scanning after day-case arthroscopy under spinal anaesthesia: comparison between lidocaine, ropivacaine, and levobupivacaine. Br J Anaesth 2003; 90: 30913
17 Schneider M, Ettlin T, Kaufmann M, et al. Transient neurologic toxicity after hyperbaric subarachnoid anesthesia with 5% lidocaine. Anesth Analg 1993; 76: 11547[ISI][Medline]
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