Hyaluronidase and peribulbar block

We have assessed the effect of two concentrations of hyaluronidase on the quality of peribulbar block, using a low volume, single injection technique. We studied 200 patients undergoing elective intraocular surgery, allocated randomly to one of three groups. Group 1 (n = 50) received peribulbar block with 5 ml of a 1:1 mixture of 0.5% plain bupivacaine and 2% plain lignocaine. Group 2 (n = 75) received this solution supplemented with hyaluronidase 50 iu ml-1. Group 3 (n = 75) received the same solution supplemented with hyaluronidase 300 iu ml-1. Lack of ocular motility was considered to be the only objective sign of successful block and movement of each rectus muscle was scored at 1-, 5- and 10-min intervals. If the block was successful at 5 min, the 10-min score was omitted. If the block was unsuccessful at 5 min, a second injection of 2% lignocaine 3 ml was given and additional assessments performed at 5-min intervals. At 1 min, ocular motility scores were significantly lower in group 3 compared with the control group (P < 0.05). The incidence of satisfactory block at 5 min was increased in both groups given hyaluronidase (group 2, P < 0.05; group 3, P < 0.001). There were no significant differences between groups 2 and 3 with respect to quality of block at 5 min. Hyaluronidase in both concentrations improved the quality of peribulbar block at 5 min, and when used in a concentration of 300 iu ml-1, also improved the speed of onset of block.      

A comparison of 1% ropivacaine with a mixture of 0.75% bupivacaine and 2% lignocaine for peribulbar anaesthesia

In a single centre, randomised, double-blind study, 54 patients underwent intraocular surgery under peribulbar anaesthesia with either ropivacaine 1% or a mixture of bupivacaine 0.75% and lignocaine 2%, both with hyaluronidase 7.5 iu.ml-1. There were no significant differences in volume of anaesthetic required, time to onset of block, peri-operative pain scores or frequency of adverse events between the ropivacaine group and the lignocaine and bupivacaine group.     

The effect of a priming epidural injection of adrenaline on epidural blockade with bupivacaine

Twenty-four patients receiving epidural anaesthesia were studied to test the hypothesis that 1:200,000 adrenaline administered into the epidural space 5 minutes before 20 ml bupivacaine 0.5% would improve nerve block and delay systemic absorption of the local anaesthetic. Group A/B received 20 ml adrenaline 1:200,000 5 minutes before 20 ml bupivacaine 0.5%, group S/BA 20 ml saline followed by 20 ml bupivacaine 0.5% with 100 micrograms adrenaline, and group S/B saline 20 ml followed by 20 ml plain bupivacaine 0.5%. Mean maximum plasma concentrations of bupivacaine tended to be lower in the adrenaline groups. A delay in the time to peak plasma concentration of bupivacaine was noted in the A/B group; this indicated that priming with adrenaline may be effective at delaying early systemic uptake of the local anaesthetic. In both adrenaline groups a more prolonged epidural block and increased efficacy were noted, although this was only significant for the duration of block at T6 (p = 0.023) and duration of motor block at Bromage level 1 (p = 0.016) in group A/B. There seems little clinical advantage in administering adrenaline 5 minutes before bupivacaine.     

Peribulbar anaesthesia: a double-blind comparison of three local anaesthetic solutions

A prospective, randomised, double-blinded study comparing three agents for peribulbar anaesthesia is reported. Sixty patients undergoing extracapsular cataract extraction under local anaesthesia were randomly allocated to receive peribulbar anaesthesia with lignocaine 2% with adrenaline; prilocaine 3% with felypressin 0.03 IU.ml-1 or 2% lignocaine and 0.5% bupivacaine in a ratio of 1:1, using a standardised two-injection technique. The pain of injection, time of onset of the block and the operating conditions at the start and finish of surgery were assessed. Peribulbar anaesthesia using lignocaine 2% was significantly more painful than the other solutions. The onset of anaesthesia adequate for surgery was similar in all three groups. Prilocaine 3% with felypressin was associated with the greatest number of blocks providing total akinesia of the eye. Inadequate duration of anaesthesia was seen in only one case; the solution used for this block was 2% lignocaine.     

Comparison of 1% ropivacaine and a mixture of 2% lignocaine and 0.5% bupivacaine for peribulbar anaesthesia in cataract surgery.

The purpose of the study was to compare 1% ropivacaine and hyaluronidase 75 units/ml with a 1:1 mixture of 2% lignocaine and 0.5% bupivacaine and hyaluronidase 75 units/ml for peribulbar anaesthesia in cataract surgery. We conducted a double-blind randomized trial involving 100 patients. Group 1 received a peribulbar injection of 8 ml of 1% ropivacaine and hyaluronidase 75 units/ml. Group 2 received a peribulbar injection of 8 ml of a 1:1 mixture of 2% lignocaine and 0.5% bupivacaine and hyaluronidase 75 units/ml. Parameters measured were ocular and eyelid movement scores, time suitable for surgery, need for supplementary injections, verbal pain score and complications. No statistical differences were found between the two groups regarding any of the study parameters. Both groups had excellent surgical analgesia and akinesia. We conclude that 1% ropivacaine is a suitable agent for single injection peribulbar anaesthesia for cataract surgery.     

Peribulbar anaesthesia using a mixture of local anaesthetic and vecuronium

The aim of this double-blind, randomised study was to assess the effects of the addition of 0.5 mg of vecuronium bromide to a standard local anaesthetic mixture used for peribulbar anaesthesia. We studied 60 patients undergoing regional anaesthesia for intra-ocular surgery and were primarily interested in the quality of globe and lid akinesia. All received a mixture of 5 ml 2% lignocaine with 1:200 000 adrenaline, 5 ml 0.75% bupivacaine and 150 IU hyaluronidase with either 0.9% saline 0.25 ml (group A, n  = 30) or vecuronium bromide 0.25 ml (0.5 mg) (group B, n  = 30). Eye movements assessed at both 5 and 10 min were significantly reduced in the vecuronium group (group B) (p < 0.05). We conclude that the addition of vecuronium at a dose of 0.5 mg to the standard local anaesthetic mixture improves the quality of globe and lid akinesia.     

Sub-Tenon's block: the effect of hyaluronidase on speed of onset and block quality

The role of hyaluronidase on the onset time and quality of single quadrant sub-Tenon's block was studied in a prospective, randomized, double-blind controlled manner. One hundred and twenty consecutive patients undergoing cataract surgery under local anaesthesia received a sub-Tenon's block with either of two local anaesthetic solutions. One consisted of 2% plain lignocaine 3 ml with 0.5% plain bupivacaine 2 ml. The other consisted of 2% lignocaine 1 ml containing 150 i.u. per ml of hyaluronidase with 2% plain lignocaine 2 ml and 0.5% plain bupivacaine 2 ml. The development of akinesia and the resulting block quality were assessed. Akinesia scores were lower at all time intervals and were significantly lower (P < 0.05) up to 9 minutes after block in the hyaluronidase group. However, block quality as assessed by the surgeon was not significantly different between the groups. The addition of 150 IU hyaluronidase significantly speeds up the onset of surgical anaesthesia produced by a sub-Tenon's block.     

Effects of famotidine and cimetidine on plasma levels of epidurally administered lignocaine

The effects of two H2-receptor antagonists, famotidine and cimetidine, on the plasma levels of epidurally administered lignocaine were studied. Group A (n = 20) received famotidine 20 mg orally the night before surgery and 20 mg intramuscularly 60 minutes before induction of anaesthesia. Group B (n = 15) received cimetidine 200 mg orally the night before the surgery and 400 mg orally 60 minutes before the anaesthetic induction. Group C (n = 20) received neither famotidine nor cimetidine and served as controls. Twelve millilitres of 2.0% lignocaine with adrenaline 1:200,000 was injected into the epidural space in all patients, after the establishment of general anaesthesia with nitrous oxide, oxygen, and enflurane (0.3-0.5%). The patients who received cimetidine showed significantly higher plasma concentrations of lignocaine compared with either group A or group C at all investigation times (p less than 0.01). The mean peak plasma concentrations were 2.4 (SEM 0.1), 3.2 (SEM 0.2) and 2.3 (SEM 0.1) micrograms/ml in group A, B, and C, respectively. This study suggests that famotidine is preferable to cimetidine for control of gastric acidity before the use of lignocaine as the epidural anaesthetic.     

Plasma catecholamine levels following topical application versus infiltration of adrenaline for nasal surgery.

Plasma catecholamine concentrations were measured after vasoconstrictor solutions were administered either by instillation (Moffett's method) or by submucosal infiltration in twenty patients undergoing elective nasal surgery. Following infiltration with 4.4 ml of 1:80,000 adrenaline and 2% lignocaine, plasma adrenaline concentrations increased by 44.3 times to a peak of 9.9 nmol.l-1 (1813 pg.ml-1) within one minute. In contrast the peak level of adrenaline in the patients receiving Moffett's solution containing 1 ml of 1:1,000 adrenaline was 1.27 nmol.l-1 (232 pg.ml-1) occurring 10 minutes after instillation of the solution. The difference in the adrenaline concentrations between the groups was statistically significant (P less than 0.01). The lack of sympathoneuronal response was confirmed by simultaneous measurements of plasma noradrenaline concentrations, which did not change significantly. The operative field was subjectively assessed to be better in the infiltrated patients and the mean operating time and measured blood loss were less in this same group of patients.     

Venous levels of lignocaine and bupivacaine after peribulbar block

Twenty-five patients undergoing elective cataract day surgery were studied after receiving a dual-injection peribulbar block with a mixture consisting of equal volumes of 2% lignocaine and 0.75% bupivacaine with hyaluronidase. A maximum of 10ml of solution was used for the initial block; supplementary injections of up to 10 ml were given to five patients. Venous blood was taken prior to the block and then 1, 10, 20, 30, 60 and 90 min after the block. The peak mean concentrations of lignocaine (0.722 μg. ml⁻¹) and bupivacaine (0.353 μg. ml⁻¹)were found at 10–20 min after injection when no top-up was given and at 10 min after the top-up injection when required. All measured serum concentrations of lignocaine and bupivacaine were below the accepted toxic levels of the two drugs. However, the highest individual toxicity score after a top-up was 0.915 which was very close to the toxicity threshold (= 1) when a scoring system was used to assess the combined levels.     

A randomised double-blind study of interpleural analgesia after cholecystectomy

Continuous interpleural analgesia provided by 4 hourly injections of 20 ml bupivacaine 0.5% with adrenaline 5 micrograms/ml was compared with placebo in a randomised, double-blind study after cholecystectomy. All patients self-administered intravenous morphine using a patient-controlled analgesia device. There was a highly significant difference in mean morphine consumption between the groups (72 mg as compared with 22 mg). Visual analogue pain scores tended to be lower in the bupivacaine group throughout and this was significant at 2 hours. Respiratory function measurements were not significantly different between the groups. The mean peak venous plasma bupivacaine concentration after the sixth dose was 3.03 micrograms/ml and no symptoms suggestive of local anaesthetic toxicity occurred. It is concluded that this regimen can provide effective and continuous analgesia after cholecystectomy and that combined administration of interpleural bupivacaine and systemic morphine is more effective than morphine alone in the immediate postoperative period. The doses of bupivacaine required for optimal use of the technique lead to significant total plasma bupivacaine concentrations within 24 hours.     

Effects of epinephrine and clonidine on plasma concentrations of spinal bupivacaine

ASA II-III patients, scheduled for peripheral vascular surgery, were included in a study designed to assess the effect of spinal epinephrine and clonidine on plasma concentrations of spinally administered 0.5% glucose-free bupivacaine. Patients were allocated randomly to three groups to receive via a spinal catheter 22.5 mg (4.5 ml) of bupivacaine alone (Group B, 9 patients) or combined with 0.3 mg epinephrine (Group BE, 10 patients) or 0.15 mg clonidine (Group BC, 10 patients). Sensory blockade was assessed by pin-prick and motor blockade on the Bromage scale. Bupivacaine plasma concentrations were measured by gas chromatography. A trend to prolongation of local anaesthetic blockade was documented in patients receiving bupivacaine plus epinephrine or clonidine. (Time to regression of sensory blockade to L2: 170 +/- 75 min in Group B, 230 +/- 50 min in Group BE, 232 +/- 64 min in Group BC.) The maximum peak concentration (Cmax), the time to reach Cmax (Tmax) and the time-concentration curve from 0-180 min (AUC) were not different for the three groups (Cmax 228 +/- 112 ng.ml-1 in Group B, 215 +/- 103 ng.ml-1 in Group BE, 234 +/- 159 ng.ml-1 in Group BC; Tmax 41 +/- 34 min in Group B, 59 +/- 31 min in Group BE, 68 +/- 32 min in Group BC; AUC 31.0 +/- 1.7 mg.ml-1.min-1 in Group B, 27.3 +/- 1.1 mg.ml-1.min-1 in Group BE, 27.0 +/- 1.1 mg.ml-1.min-1 in Group BC). The results of this study suggest that epinephrine and clonidine do not decrease blood resorption of spinal bupivacaine.     

The effects of volume and speed of injection in peribulbar anaesthesia

We have evaluated the effects of the volume and speed of administration of local anaesthetic during peribulbar anaesthesia. One hundred and forty patients scheduled for cataract surgery were randomly allocated to one of four groups of 35. Each patient received an injection of the same mixture of lignocaine, bupivacaine and hyaluronidase. Patients in group A were given 9 ml at a speed of 5 mlmin⁻¹, group B were given the same volume at 12 mlmin⁻¹, group C were given 13.5 ml at 5 mlmin⁻¹ and group D were given 13.5 ml at 12 mlmin⁻¹. A significantly higher incidence of satisfactory akinesia was found in group D, whose pain score at injection was no higher than for the other groups. Large volumes of local anaesthetic significantly affected intra-ocular pressure. The incidences of early and late ptosis or diplopia were not affected by either the rate of injection or the volume of local anaesthetic.     

A randomized controlled trial of continuous extra-pleural analgesia post-thoracotomy: efficacy and choice of local anaesthetic

Controversy persists over the efficacy of intercostal nerve block administered through a tunnelled extrapleural catheter. We have undertaken a randomized, prospective double-blind trial of two different local anaesthetic regimes to evaluate the effect of this technique on post-thoracotomy pain relief and pulmonary function. Sixty-eight patients were randomized to receive bupivacaine 0.25% (n = 22), lignocaine 1% (n = 21) or 0.9% NaCl (saline) (n = 20) via an extrapleural catheter, inserted peroperatively. All patients underwent a standard posterolateral thoracotomy. Pain was assessed using a visual analogue pain score and by the requirement for opiate analgesia. Pulmonary function was measured using bedside spirometry. Pain scores were lower in the local anaesthetic groups at 24, 32 and 72 h compared with placebo (P < 0.05) and the total amount of opiate required was less than placebo for both lignocaine and bupivicaine (P < 0.05). Pulmonary function was better in the local anaesthetic groups throughout the post-operative period and was most pronounced at 24 h with a mean improvement of 30% for forced expiratory volume (FEV1), 24% for forced vital capacity (FVC) and 19% for peak expiratory flow rate (PEFR) compared with placebo. There was no significant difference between pain scores, opiate requirement or pulmonary function between lignocaine and bupivicaine. CT scanning demonstrated containment of the local anaesthetic in an extra-pleural tunnel. Extra-pleural infusion of local anaesthetics is a simple technique, with low risk of complications and provides effective pain relief as well as an improvement in post-operative pulmonary function. Lignocaine is equally as effective as bupivacaine and its use would result in some cost-saving.     

Speed of onset of sensory block for elective extradural Caesarean section: choice of agent and temperature of injectate

We have studied the effects of choice of local anaesthetic andtemperature of extradural injectate on speed of onset of sensoryblock for elective extradural Caesarean section in a double-blindtrial in 120 women allocated randomly to one of four groupsto receive either plain 0.5% bupivacaine or 2% lignocaine with1:200000 adrenaline at either room temperature or 38°C.The onset time of lignocaine with adrenaline was shorter thanthat of bupivacaine regardless of temperature (P < 0.01).Warmed lignocaine produced the most rapid block overall (P <0.025). The incidence of hypotension, ephedrine requirement,shivering, quality of analgesia and additional analgesic requirementswere similar for all groups.     

Effect of addition of clonidine to local anaesthetic mixture for peribulbar block

Clonidine added to local anaesthetics prolongs the duration of anaesthesia and analgesia of peripheral, neuraxial and retrobulbar blocks. The present randomized blinded controlled study was conducted to evaluate the effect of the addition of clonidine to local anaesthetic mixture on the quality, onset time, duration of peribulbar block, perioperative analgesia and patients' comfort. The study comprised two groups of 12 patients each. Group A (control) patients received 7 ml of a mixture of 2% lignocaine and hyaluronidase with 1 ml normal saline, while group B (clonidine group) patients had clonidine 1 microg/kg added to the above mixture. Onset and duration of lid akinesia, globe anaesthesia and akinesia, time to first analgesic medication and total analgesic requirement were assessed. Patients were monitored for heart rate, blood pressure, sedation and respiratory depression. Addition of clonidine to local anaesthetic mixture resulted in a significant increase in duration of lid akinesia (85.4+/-25.6 vs 173.3+/-35.3 min, P<0.001), globe anaesthesia (63.2+/-6.9 vs 78.8+/-17.5 min, P=0.012) and globe akinesia (161.3+/-24.3 vs 201.2+/-45.7 min, P=0.016). The onset time and quality of block were similar in both the groups. No significant haemodynamic, respiratory or sedative effects were recorded. The perioperative pain scores and the analgesic requirements were significantly (P<0.01) lower in group B patients. We found that addition of clonidine 1 microg/kg to local anaesthetic mixture significantly increases the duration of anaesthesia and analgesia after peribulbar block.     

Hyaluronidase as an adjuvant in bupivacaine-lidocaine mixture for retrobulbar/peribulbar block

Hyaluronidase 7.5 IU/mL added to the local anesthetic improves peribulbar block, but smaller concentrations have not been shown to be effective. In this prospective, double-blinded study, 714 consecutive ocular surgery patients were randomized into three groups: no hyaluronidase (n = 241), hyaluronidase 3.75 IU/mL (n = 244), and hyaluronidase 7.5 IU/mL (n = 229). Retrobulbar/peribulbar block was performed with two injections of a 1:1 mixture of bupivacaine 0.75% and lidocaine 2%, 6-8 mL. Patient data were collected on demographics, initial volume of local anesthetic, need for supplementary block, and akinesia of the anesthetized eye. When hyaluronidase was used (3.75 or 7.5 IU/mL), the initial block was sufficient and the anesthetized eye was akinetic significantly more often than in the group without hyaluronidase. The hyaluronidase groups (3.75 and 7.5 IU/mL) did not differ significantly in any respect. We conclude that the addition of hyaluronidase 3.75 or 7.5 IU/mL improved the success of the initial retrobulbar/peribulbar block and akinesia and reduced the need for supplementary block. Implications: We conclude that the addition of hyaluronidase 3.75 or 7.5 IU/mL improved the success of the initial retrobulbar/peribulbar block and akinesia and reduced the need for supplementary block.     

Intraocular pressure and ropivacaine in peribulbar block: a comparative study with bupivacaine

BACKGROUND: The aim of this study was to compare the effects on intraocular pressure (IOP) of ropivacaine and bupivacaine in peribulbar block. METHODS: The study involved 40 patients with ASA physical status I, II or III undergoing cataract surgery under peribulbar block. Patients were allocated to two groups according to the local anesthetic used: Group R (n=20), 1.0% ropivacaine and Group B (n=20) 0.75% bupivacaine, both associated with 50 IU. ml-1 hyaluronidase, in peribulbar double injection technique. IOP was measured at four time points: 0=before block (control); 1=1 min after block; 2=5 min after block; 3=15 min after block. RESULTS: Mean values of IOP (mm Hg) after block were significantly lower in Group R in comparison to Group B: time point 1=13.4+/-3.2 vs 20.8+/-4.7; time point 2=10.9+/-3.7 vs 14.4+/-3.8; time point 3=7.7+/-4.0 vs 10.5+/-3.1. The variation of IOP was different in each group. In Group R, the mean values obtained at the three time points after block were significantly lower than the control; in Group B, the mean value of IOP rose significantly 1 min after block and was lower than control only at time point 3. CONCLUSIONS: Ropivacaine 1.0% associated with hyaluronidase in peribulbar block is better than 0.75% bupivacaine under the same standard conditions for lowering IOP in intraocular surgery. This effect is probably due to relaxation of the extraocular muscles after the block with both anesthetics, and possibly to a smaller intraocular blood volume due to vasoconstriction in the case of ropivacaine.     

PLASMA CONCENTRATIONS OF LOCAL ANAESTHETICS AFTER INTERSCALENE BRACHIAL PLEXUS BLOCK

Plasma concentrations of local anaesthetic agents have beenmeasured after 40 interscalene brachial plexus blocks in 39patients, using lignocaine, prilocaine, bupivacaine and etidocaine.Lignocaine produced greater concentrations than prilocaine,and bupivacaine greater concentrations than etidocaine. Theaddition of adrenaline resulted in much lower concentrationsin the case of all four agents.     

EXTRADURAL ANALGESIA IN OBSTETRICS: A CONTROLLED TRIAL OF CARBONATED LIGNOCAINE AND BUPIVACAINE HYDROCHLORIDE WITH OR WITHOUT ADRENALINE

Four local anaesthetic solutions (2% carbonated lignocaine withor without adrenaline and 0.5% bupivacaine HCl with or withoutadrenaline) were used randomly for 335 continuous lumbar extra-duralblocks in labour. Carbonated lignocaine caused a more rapidonset of analgesia than bupivacaine HCl. The addition of adrenalinemade little difference to the onset times, prolonged markedlythe duration of analgesia with carbonated lignocaine and hadlittle effect on the duration of analgesia with bupivacaineHCl. Tachyphylaxis was a feature with carbonated lignocaineand adrenaline, but not with the other solutions. The incidenceof unblocked segments was 7–9% in the four groups. Theincidence of unilateral analgesia was 6% with plain lignocaineand 13% in the other groups! Complete pain relief occurred morefrequently with bupivacaine HCl than with carbonated lignocaineand the use of adrenaline had little effect on the degree ofanalgesia.