1 University Department of Anaesthesia, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK. 2 Present address: Department of Anaesthetics, St Johns Hospital, Livingston, West Lothian, UK
Corresponding author. E-mail: j.a.w.wildsmith@dundee.ac.uk This work was presented in abstract form at the European Society of Regional Anaesthesia meeting, Rome, September 2023, 2000, and at the Anaesthetic Research Society, Newcastle, UK, March 2930, 2001.
Accepted for publication: October 17, 2002
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Methods. Forty ASA grade III patients undergoing lower-abdominal, perineal or lower-limb surgery under spinal anaesthesia were recruited and randomized to receive ropivacaine 5 mg ml1 (with glucose 50 mg ml1), 3 ml or bupivacaine 5 mg ml1 (with glucose 80 mg ml1), 3 ml. The level and duration of sensory block, intensity and duration of motor block, and time to mobilize and micturate were recorded. Patients were interviewed at 24 h and at 1 week to identify any residual problems.
Results. All blocks were adequate for the proposed surgery, but there were significant differences between the two groups in mean time to onset of sensory block at T10 (ropivacaine 5 min; bupivacaine 2 min; P<0.005), median maximum extent (ropivacaine T7; bupivacaine T5; P<0.005) and mean duration of sensory block at T10 (ropivacaine 56.5 min; bupivacaine 118 min; P=0.001). Patients receiving ropivacaine mobilized sooner (ropivacaine mean 253.5 min; bupivacaine 331 min; P=0.002) and passed urine sooner (ropivacaine mean 276 min; bupivacaine 340.5 min; P=0.01) than those receiving bupivacaine. More patients in the bupivacaine group required treatment for hypotension (>30% decrease in systolic pressure; P=0.001).
Conclusions. Ropivacaine 15 mg in glucose 50 mg ml1 provides reliable spinal anaesthesia of shorter duration and with less hypotension than bupivacaine. The recovery profile for ropivacaine may be of interest given that more surgery is being performed in the day-case setting.
Br J Anaesth 2003; 90: 3048
Keywords: anaesthetics local, bupivacaine; anaesthetics local, ropivacaine; anaesthetic techniques, subarachnoid
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
On arrival in the anaesthetic room, continuous monitoring with ECG, non-invasive arterial pressure and pulse oximetry were started, and a suitable peripheral vein was cannulated. No fluid was administered and the patient was placed in the left lateral position for lumbar puncture, which was performed using a midline approach at the second or third interspace. A 25-swg Whitacre needle (Vygon, UK) was inserted with the distal port facing laterally, and the appropriate local anaesthetic solution was injected over 1015 s. The ropivacaine solutions were prepared aseptically immediately before injection (by an anaesthetist who was not one of the investigators) using equal volumes of ropivacaine 10 mg ml1 and glucose 100 mg ml1 (Table 1). The bupivacaine solution used was commercially available in the UK (Marcain 0.5% Heavy®, AstraZeneca). The patient was placed supine immediately after injection.
|
Statistical analysis
The sample size was chosen to show a difference in extent of sensory block of two dermatomes (SD one dermatome) between the groups, based on an risk of 0.05 and a ß risk of 0.10 using data from a previous study of intrathecal ropivacaine.5 Data are presented as median (range), mean (SD) or frequencies, as appropriate. Patient characteristics and the duration of surgery were compared using the two-tailed, two-sample t-test except for sex (
2-test). Block characteristics were compared using the two-tailed MannWhitney U-test or Fishers exact test (number of patients with complete motor block). A Bonferroni correction was applied for multiple two-way testing. In all categories P<0.05 was considered statistically significant. Data were analysed using Arcus Quickstat version 1.0 (Research Solutions Ltd, UK).
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
There were marked differences in cardiovascular changes between the groups (Fig. 2). In the bupivacaine group, 14 (70%) patients required ephedrine for a per protocol decrease in systolic pressure, compared with only three (15%) patients in the ropivacaine group (P=0.001).
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The results of the current study are also in contrast with the general conclusions of two more recent studies of intrathecal ropivacaine, both of which questioned its suitability for spinal anaesthesia compared with bupivacaine.34 Gautier and colleagues3 used plain glucose-free preparations, but in larger volumes of less concentrated solutions than are normally used in clinical practice. When equal doses of ropivacaine and bupivacaine were compared, the onset and extent of sensory block were similar, but both the duration of that sensory block and the degree of motor block produced were less with ropivacaine. These findings, particularly the shorter duration of sensory block, led the authors to claim that ropivacaine is less potent than bupivacaine and that it offers no significant advantage, even though the patients who received ropivacaine passed urine and mobilized sooner than those who received bupivacaine.
In the other recent study, McDonald and colleagues4 compared hyperbaric preparations of ropivacaine and bupivacaine in volunteers not undergoing surgery. Their solutions were also less concentrated than those normally used clinically, and the total doses injected were lower. Equal doses of ropivacaine and bupivacaine produced sensory blocks of similar onset and extent, but there was less motor block, which regressed faster, with ropivacaine. Again, primarily on the basis of the shorter duration of action and despite equivalence in the onset and extent of sensory block, the authors concluded that ropivacaine is less potent than bupivacaine. Their study also found a higher incidence of backache after ropivacaine and concluded that the incidence of side-effects was higher even though the difference was not statistically significant.
Because our initial experience with intrathecal ropivacaine was not in accord with the conclusions of these studies, we decided to compare it directly with bupivacaine, using glucose-containing solutions of both. The concentration of glucose in the ropivacaine solution was lower than that of the bupivacaine for two reasons. First, a previous study had demonstrated the clinical efficacy of a solution of ropivacaine containing glucose 50 mg ml1,5 which, in the absence of a commercially available glucose-containing solution, is easily prepared before spinal anaesthesia. Second, previous work with bupivacaine had suggested that lower concentrations of glucose than are present in the commercially available hyperbaric solution may be sufficient to provide the previously stated benefits over plain solutions.9 10
Compared with the commercial preparation of bupivacaine, the ropivacaine preparation used in this study produced a somewhat slower onset of slightly less extensive sensory block, which regressed more rapidly. These differences could be the result of the different glucose concentrations on intrathecal spread, differences between the drugs themselves, or a combination of the two. Currently, many consider that ropivacaine has a less potent sensory blocking effect than bupivacaine because of the conclusions of the two studies referred to above.3 4 However, in both of those studies solutions apparently equal in baricity produced sensory blocks of the same rate of onset and extent of block, which suggests that the differences we observed in those aspects of block were the result of the difference in the baricities of our solutions, but further study is needed to establish the exact position. That intrathecal ropivacaine has a shorter duration of sensory effect than bupivacaine is a general finding, but this does not support definitively the conclusion that it is less potent, and certainly not that it is unsuitable for clinical use by this route. The potency of a drug relates to the effect produced (not the duration of that effect), and both the preparations we studied produced blocks that were effective for the surgery undertaken.
There is general agreement that ropivacaine has a less potent effect on motor nerves, confirmed in this study, with both the degree and duration of motor block produced by ropivacaine being less, although still adequate for the projected surgery. This adds to the now considerable body of evidence suggesting that there is a greater degree of sensorymotor separation when using ropivacaine compared with bupivacaine,13 14 and supports our view that ropivacaine is an agent worthy of further study as an agent for spinal anaesthesia. Good sensory blocks were associated with a highly favourable recovery profile compared with bupivacaine, with more rapid regression of sensory and motor block, earlier mobilization and shorter time to first micturition. With the current emphasis on ambulatory surgery, such a recovery profile may be of benefit. Hyperbaric lidocaine 5% has been used as a short-acting agent for ambulatory spinal anaesthesia, but concerns about the high incidence of transient neurological symptoms restrict its use currently.15 We found no evidence of any late sequelae such as backache or other transient symptoms in this or a previous study of ropivacaine.5
In conclusion, a solution of ropivacaine that is hyperbaric relative to cerebrospinal fluid can be used to provide reliable spinal anaesthesia that is comparable to that with hyperbaric bupivacaine in terms of quality of block, but with a shorter recovery profile. The key issue is the difference in the clinical profile of the block (onset, extent, suitability for surgery, duration) produced, not the relative potencies of the two drugs. However, further work is required to evaluate the role of hyperbaric ropivacaine for surgical procedures of short-to-intermediate duration, particularly in the ambulatory setting.
![]() |
Acknowledgement |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 Wahedi W, Nolte H, Klein P. Ropivacaine in spinal anaesthesia. Anaesthesist 1996; 45: 73744[CrossRef][ISI][Medline]
3 Gautier PE, De Kock M, Van Steenberge A, et al. Intrathecal ropivacaine for ambulatory surgery: A comparison between intrathecal bupivacaine and ropivacaine for knee surgery. Anesthesiology 1999; 91: 123945[ISI][Medline]
4 McDonald SB, Liu SS, Kopacz DJ, Stephenson CA. Hyperbaric spinal ropivacaine: A comparison to bupivacaine in volunteers. Anesthesiology 1999; 90: 9717[ISI][Medline]
5 Whiteside J, Burke D, Wildsmith JAW. A comparison of 0.5% ropivacaine (5% glucose) with 0.5% ropivacaine (1% glucose) when used to provide spinal anaesthesia for elective surgery. Br J Anaesth 2001; 86: 2414
6 McNamee DA, Parks L, McCelleand 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
7 Schiffer E, Van Gessel E, Gamulin Z. Influence of sex on cerebrospinal fluid density in adults. Br J Anaesth 1999; 83: 9434
8 Lee A, Ray D, Littlwood DG, Wildsmith JAW. Effect of dextrose concentration on the intrathecal spread of amethocaine. Br J Anaesth 1988; 61: 1358[Abstract]
9 Bannister J, McClure JH, Wildsmith JAW. Effect of glucose concentration on the intrathecal spread of 0.5% bupivacaine. Br J Anaesth 1990; 64: 2324[Abstract]
10 Chambers WA, Edstrom HH, Scott DB. Effect of baricity on spinal anaesthesia with bupivacaine. Br J Anaesth 1981; 53: 27982[Abstract]
11 Logan MR, McClure JH, Wildsmith JAW. Plain bupivacaine: an unpredictable spinal anaesthetic agent. Br J Anaesth 1986; 58: 2926[Abstract]
12 Sanderson P, Read J, Littlewood DG, McKeown D, Wildsmith JAW. Interaction between baricity (glucose concentration) and other factors influencing intrathecal drug spread. Br J Anaesth 1994; 73: 7446[Abstract]
13 Brockway MS, Bannister J, McClure JH, McKeown D, Wildsmith JAW. Comparison of extradural ropivacaine and bupivacaine. Br J Anaesth 1991; 66: 317[Abstract]
14 Morrisson LMM, Emanuelsson BM, McClure JH, et al. Efficacy and kinetics of extradural ropivacaine: comparison with bupivacaine. Br J Anaesth 1994; 72: 26973
15 Schneider M, Ettlin T, Kaufmann M, et al. Transient neurologic toxicity after hyperbaric subarachnoid anaesthesia with 5% lidocaine. Anesth Analg 1993; 76: 11547[ISI][Medline]