Extending low-dose epidural analgesia for emergency Caesarean section. A comparison of three solutions

We conducted a prospective double-blind randomised trial to compare bupivacaine 0.5%; a 50 : 50 mixture of bupivacaine 0.5%/lignocaine 2% with 1 : 200 000 adrenaline (final concentration); and lignocaine 2% with 1 : 200 000 adrenaline for converting a low-dose labour epidural into a block adequate for emergency Caesarean section. Ninety patients were studied, 30 in each group. There was no difference between the groups in the time taken for bilateral loss of cold sensation to reach T4. Onset time was unaffected by the existing sensory level pre-Caesarean section top-up; the number of low-dose top-ups in labour; the total dose of bupivacaine in labour; or maternal weight or height. Three patients in the lignocaine with adrenaline group had blocks that reached the cervical dermatomes and three in the same group required general anaesthesia for inadequate anaesthesia, compared with none in the other groups (both p = 0.04).     

CHANGES IN PLASMA CATECHOLAMINE CONCENTRATIONS FOLLOWING INFILTRATION WITH LARGE VOLUMES OF LOCAL ANAESTHETIC SOLUTION CONTAINING ADRENALINE

Plasma catecholamine concentrations have been measured in ninepatients undergoing rhinoplasty following infiltration to thefacial area of 21 ml of 0.5% lignocaine with adrenaline 1: 200000 and in seven patients undergoing brachial plexus blockadewith 40 ml of 0.5% lignocaine, 0.25% bupivacaine and adrenaline1: 200 000. In the rhinoplasty group there was a 566% increasein plasma adrenaline concentration 2 min after cessation ofinfiltration, whilst in the brachial plexus group a 112% increasein the plasma concentration of adrenaline occurred at 10 minafter completion of the block. There was no change in plasmanoradrenaline concentration in either group. It is concludedthat the so-called safe dose of adrenaline (1.0 fig kg–¹during halothane anaesthesia) is meaningless unless the siteof administration is specified.     

VENOUS PLASMA (TOTAL) BUPIVACAINE CONCENTRATIONS FOLLOWING LOWER ABDOMINAL FIELD BLOCK

Following local anaesthesia of the lower abdominal wall, inpatients undergoing laparoscopic sterilization (n = 16), using0.5% plain bupiv acaine 40 ml (n = 8), or 0.5% bupivacaine with1:200 000 adrenaline (n = 8), venous plasma (total) bupivacaineconcentrations were measured (gas-liquid chromatography) atintervals up to 2 h after the local anaesthetic was injected.Mean peak plasma venous concentration achieved following 0.5%plain bupivacaine was 2.23 ± 0.24 pg ml^–1 (mean± SEM), while the mean peak concentration following 0.5%bupivacaine with adrenaline was 0.98 ± 0.10 pg ml^–1(mean ± SEM). At all sampling times up to and including45 min after the injection of local anaesthetic, the plasmaconcentrations were significantly less in the bupivacaine withadrenaline group when compared with the group in whom a plainsolution was used.     

Regional anaesthesia for surgery of the forearm and hand

Eighty patients who presented for surgery of the forearm or hand were allocated randomly to one of two groups. In Group A, surgery was performed under supraclavicular brachial plexus block only; a mixture of equal parts of prilocaine 1% and bupivacaine 0.5% without adrenaline was used. In Group B, supraclavicular brachial plexus block was performed using prilocaine 1% alone, but in addition discrete nerve blocks were performed at elbow level using 0.5% bupivacaine without adrenaline. Patients in Group B had a significantly shorter duration of unwanted postoperative motor blockade and a significantly longer duration of postoperative analgesia (p less than 0.005).     

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.     

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.     

Effects of Adjuvants to Local Anaesthetics on Their Duration

Local anaesthetics of the amide type were studied in a modified rat infraorbital nerve block model, with which it was possible to determine varying degrees of sensory block. Of the agents investigated, 0.5% bupivacaine tended to give a longer duration of block than 2% prilocaine or 2% lidocaine, while 0.5% etidocaine had the shortest duration. The duration of prilocaine was prolonged by addition of adrenaline, 5 micrograms/ml, more than that of the other agents. Addition of dextrans of Mw 40-110 X 10(3) did not cause any prolongation of block induced by bupivacaine. When mixed with dextrans over a wide range of Mw (40-4900 X 10(3), prilocaine exhibited significant prolongations of its action by up to 200%. The extent of prolongation was dependent on the degree of block, the concentration of dextrans in the local anaesthetic solution, and the Mw of the dextran although in a less uniform way. An increase in the relative viscosity of the solutions might be a factor of importance for the prolonging effect of addition of dextran to local anaesthetics. Since a formulation providing analgesia of a long duration would be of clinical value, further studies on combinations of the comparatively low-toxicity agent prilocaine and macromolecular substances are of interest.     

Prolonged local analgesia for inguinal herniorrhaphy with bupivacaine and dextran.

In a randomised double-blind trial 40 patients undergoing unilateral inguinal herniorrhaphy were each locally anaesthetised with one of a series of 8 solutions. These contained bupivacaine, both with and without adrenaline, mixed with an equal volume of dextran 40, dextran 70, dextran 110, or saline. Significant prolongation of local analgesia was achieved with high-molecular-weight dextran and this was most consistently obtained when the solution used contained adrenaline. The possible influence of the pH of the solutions used, together with the ways in which dextran may affect the duration of action of bupivacaine are discussed.     

EXTRADURAL DIAMORPHINE WITH ADRENALINE IN LABOUR: COMPARISON WITH DIAMORPHINE AND BUPIVACAINE

In a randomized double-blind study of 51 primigravida, we haveexamined the relative efficacies of bupivacaine, diamorphineor diamorphine with adrenaline given by the extradural routefor relief of pain during labour. Group 1 (n = 18) receiveddiamorphine 5 mg in 0.9% sodium chloride 8 ml; group 2 (n =19) received diamorphine 5 mg in 0.9% sodium chloride 8 ml with1: 200 000 adrenaline; group 3 (n = 14) received 0.375% bupivacaine8 ml. All patients received 0.375% bupivacaine 8 ml as a supplementafter the initial analgesia had subsided. Patients in all groupshad satisfactory and comparable analgesia 20 min after the initialinjection. However, after 60 min and up to 8 h, analgesia wassuperior in group 2 as assessed by linear analogue pain scores,with statistical significance at 4, 6 and 8 h. Groups 1 and2 required bupivacaine supplements less frequently than group3 (P < 0.001). There were no serious adverse effects in anygroup, but pruritus was a feature in the diamorphine groups.Diamorphine 5 mg may be used as an alternative to bupivacaine0.375% 8 ml in the first stage of labour and provides a longerduration of action. The addition of adrenaline 1: 200 000 appearsto augment both the quality and duration of analgesia.     

Local analgesic and vascular effects of intradermal ropivacaine and bupivacaine in various concentrations with and without addition of adrenaline in man

Ropivacaine, a new long–acting amino–amide local anaesthetic agent, and bupivacaine, in various concentrations with or without addition of adrenaline, were tested in a randomized, double–blind study using intradermal wheals. Ten non–smoking, healthy, young male volunteers participated. In series I plain solutions of ropivacaine (0.25%, 0.5%, 0.75% and 1%) and bupivacaine (0.25%, 0.5% and 0.75%) were injected intradermally and in series II the same concentrations, with the addition of adrenaline 5 ug ml^-1 ( 1 :200 000), were used. The same volunteers took part in both series, with an interval of at least three weeks between the experiments. Saline was included as control in both series. Pin–pricking was used to assess the dermal analgesia. Plain solutions of ropivacaine produced significantly longer durations of dermal analgesia than did plain solutions of bupivacaine, in all tested concentrations. A significant increase in duration was seen for both local anaesthetics when adding adrenaline. Local vascular effects at the injected areas were determined by visual inspection (nil, pink, pale). Local blanching (pale) was significantly more frequent for plain solutions of ropivacaine, in all tested concentrations. Local redness (pink) was significantly more frequent with plain bupivacaine, in a dose–dependent relation. An initial redness was frequently observed for both local anaesthetics containing adrenaline, followed by blanching at most sites.     

Spinal anaesthesia for inguinal herniotomy in preterm infants sedated with nitrous oxide: a comparison of lumbar puncture in the lateral or sitting position

This study compares spinal anaesthesia for inguinal herniotomy in preterm infants in the lateral or sitting position. Thirty patients were randomly divided into two equal groups. One hour before spinal anaesthesia, a eutetic mixture of local anaesthetic cream was applied to the lower lumbar spine. Sedation with nitrous oxide 50% in oxygen was given to all patients before and during induction of spinal anaesthesia, and throughout surgery. Lumbar punctures were performed at the L4-5 interspace using a 2.5 cm 22 G needle. Isobaric bupivacaine 0.5% with epinephrine 1 : 200 000 at a bupivacaine dose of 1 mg.kg-1 was injected in the lateral or sitting position. Measurements included heart rate, blood pressure, oxygen saturation, maximum sensory block height and duration of motor block and analgesia. There were no statistically significant differences between the groups in any measured parameters. Median [range] maximum block height was T5[T4-T7] in the lateral group and T5[T4-T5] in the sitting group. The median [range] duration of motor blockade was 67 [50-85] min in the lateral group and 63 [50-80] min in the sitting group. Our results indicate that in preterm infants sedated with nitrous oxide, spinal anaesthesia for inguinal herniotomy performed with isobaric bupivacaine 0.5% at a dose 1.0 mg.kg-1 in the lateral or sitting position is equally effective and is associated with minimal side effects.     

Plasma bupivacaine Concentrations following psoas comprirtment block

Fourteen patients undergoing hip replacement surgery under psoas compartment block combined with general anaesthesia were studied. Group 1 (n = 7) received plain and Group 2 (n = 7) received 0.25% bupivacaine with adrenaline. The mean maximum peak concentrations were 1.93 (SEM 0.46) micrograms/ml and 1.04 (SEM 0.19) micrograms/ml at 10 minutes in groups 1 and 2 respectively. Bupivacaine concentrations were higher at all times in the group which received plain than the group receiving solution containing adrenaline. These differences were statistically significant at 10, 15 (p less than 0.05) and 30 minutes (p less than 0.025). The highest recorded plasma bupivacaine concentration was 4.54 micrograms/ml in one patient receiving plain bupivacaine. No patient developed any signs of toxic symptoms. The duration of analgesia was longer (p less than 0.005) in the group receiving bupivacaine with adrenaline. Bupivacaine 0.25% with adrenaline 1:200 000 is safe for psoas compartment block, and is recommended for hip surgery.     

Local anaesthesia in inguinal herniorrhaphy: influence of dextran and saline solutions on duration of action of bupivacaine.

Because recent clinical trials have shown that dextran solutions can prolong the local anaesthetic action of 0.25% bupivacaine, a prospective double blind trial was performed in patients (n = 50) undergoing uncomplicated elective inguinal herniorrhaphy under local anaesthesia alone. Patients were randomised prior to infiltration of local anaesthesia into 2 groups: 0.5% bupivacaine (30 ml) diluted with an equal volume of either 0.9% saline or an equal volume of dextran 110. There was no significant difference in duration nor degree of postoperative anaesthesia between the two groups. Dextran solutions were found to be significantly more acidic than saline solutions and the possible effects of this on bupivacaine kinetics are discussed.     

BUPIVACAINE WITH AND WITHOUT ADRENALINE IN INTERSCALENE BRACHIAL PLEXUS BLOCKADE

The action of adrenaline on the pharmacokinetics of bupivacainehas been tested during two successive interscalene brachialplexus blocks in 10 patients with rheumatoid arthritis. Themean venous serum C_max of bupivacaine after using it with orwithout adrenaline 1:200 000 were 1.49±0.41 µgml^–1 and 2.46±0.85 µg ml^–1 respectively.In spite of relatively high total serum concentrations, we couldnot detect any evidence of toxicity from bupivacaine. Significanttachycardia was seen after bupivacaine with adrenaline, butsystolic and diastolic arterial pressures did not change significantlyin any session. Marked subjective side effects were noticedonly after bupivacaine with adrenaline (shivering twice andpalpitations once). The serum protein bound fraction of bupivacainewas higher in rheumatic patients than in our healthy controls:97.1±2.4% and 91.3±;3.6%, respectively. Thus bupivacaineas a local anaesthetic agent seems to be even safer in patientswith rheumatoid arthritis than in normal healthy volunteers,because of lower free fraction in the former. ^* Also Paimio Hospital, Paimio, Finland.     

Comparison of articaine and bupivacaine/lidocaine for single medial canthus peribulbar anaesthesia

In a single-centre, randomized, double-blind study, we comparedthe efficacy of 2% articaine with that of a mixture of 0.5%bupivacaine and 2% lidocaine for peribulbar anaesthesia in cataractsurgery, using a single medial canthus injection technique.Eighty-two patients were allocated randomly to receive 7–9 mlof a mixture of 0.5% bupivacaine and 2% lidocaine or an equalvolume of 2% articaine with 1:200 000 epinephrine. Hyaluronidase30 iu ml^–1 was added to both solutions. Thedegree of akinesia was scored 1, 5 and 10 min after theblock, at the end of surgery and at discharge from the day caseunit. Primary outcome measures were the difference in ocularmovement scores 5 min after block and the need for supplementaryinferolateral injections. There was greater akinesia in thearticaine group at 5 min (P=0.01). Ten patients (24%) inthe articaine group and 21 patients (51%) in the bupivacaine/lidocainegroup required a supplementary injection (P=0.02). The mean(SD) volume of local anaesthetic required to achieve adequateblock for surgery was 9.7 (2.1) ml in the articaine group and11.0 (2.2) ml in the bupivacaine/lidocaine group (P=0.01). Therewas a faster offset of akinesia after surgery in the articainegroup (P=0.01). There were no differences between groups inthe incidence of reported pain or of minor complications. Inour study, 2% articaine with 1:200 000 epinephrine wassafe and efficacious for single medial canthus peribulbar anaesthesia. Br J Anaesth 2001; 87: 584–7     

COMPARISON OF INCREMENTAL SPINAL ANAESTHESIA USING A 32-GAUGE CATHETER WITH EXTRADURAL ANAESTHESIA FOR ELECTIVE CAESAREAN SECTION

Forty-three mothers who had requested regional anaesthesia forelective Caesarean section were allocated randomly to receiveeither extradural anaesthesia with pH-adjusted 2% lignocainewith 1/200 000 adrenaline, or incremental spinal anaesthesiausing a 32-gauge catheter with 0.5% plain bupivacaine. Incrementsof lignocaine or bupivacaine were given with the aim of achievinga block from T4 to S5. The spinal catheter was quicker to place(median 3 min, range 1–45 min, compared with median 10min, range 1.5–50 min) and spinal anaesthesia was quickerto establish (median 20 min, range 10–46 min comparedwith median 48 min, range 15–59 min) compared with theextradural technique. The maximum height of the spinal blockwas significantly higher (median T3–4, range T5–T3)than the extradural group (median T5, range T6–T3). Thetotal dose of intrathecal 0.5% bupivacaine was unpredictable,with a mean dose of 2.7 ml and a range between 1.5 ml and 7.4ml. Haemodynamic stability and the quality of the block weresimilar between the groups. There were two mild spinal headachesin the spinal group. All the spinal catheters were removed intact.     

Effect of scalp block on postoperative pain relief in craniotomy patients

The efficacy of scalp nerve block using 0.5% bupivacaine with adrenaline for postoperative pain relief in craniotomy patients was evaluated in 40 ASA I or II adult patients undergoing supratentorial craniotomy. A standard general anaesthesia technique was followed. Patients were randomly divided into two groups. Group B received 0.5% bupivacaine with 1:400,000 adrenaline and group S received normal saline with 1:400,000 adrenaline, both after skin closure. Postoperative pain was assessed at 30 seconds and 1, 2, 4, 6, 8 and 12 hours using a numerical rating scale. Diclofenac IM was administered as rescue analgesia if patients reported a numerical rating scale of 40 or more. Tramadol IV was administered as second rescue analgesia. Sixty per cent of patients in group S experienced moderate to severe pain (numerical rating scale of 40 or more) at some time during the first 12 postoperative hours in comparison to 25% patients in group B. Median pain scores were significantly lower in group B for up to 6 hours. Significantly more patients were pain free up to four hours in group B. Median duration for the requirement of first dose of diclofenac was longer in group B compared to group S (360 min vs 30 min, P < 0.01). The number of doses of diclofenac (5 vs 19) was significantly lower in group B compared to group S (P < 0.01). Tramadol was required by six patients in group S only. Scalp nerve block using 0.5% bupivacaine with 1:400,000 adrenaline decreases the incidence and severity of postoperative pain in patients undergoing supratentorial craniotomy.     

Fentanyl and bupivacaine mixture for extradural blockade in orthopaedic surgery: effects on haemodynamic responses and pain related to the use of thigh tourniquet

Analgesic and haemodynamic changes due to tourniquet application were investigated in a prospective double-blind study on orthopaedic patients submitted to extradural lumbar blockade with a bupivacaine and fentanyl mixture. The study was carried out in 161 healthy patients undergoing limb surgery with a thigh tourniquet. Patients were randomly assigned to two groups: each group received treatment with bupivacaine 0.5% containing 1:200,000 adrenaline. Normal saline (B:F o group) or 200 micrograms fentanyl (B:F 200 group) was added to this solution. An immediate increase in systolic and diastolic blood pressure (SBP and DBP) was provoked by tourniquet application in all patients, whilst heart rate (HR) showed no modification and the rate-pressure product (RPP) was hardly influenced in the B:F 200 group. A dramatic reduction in intra-operative supplemental analgesic needs was observed in the B:F 200 group. This group of patients also complained less of tourniquet pain than their counterparts, for the first 30 min of application. Our study underlines the value of fentanyl addition to bupivacaine in extradural blockade in orthopaedic surgery.     

Effect of adrenaline on plasma concentrations of fentanyl during epidural anaesthesia for caesarean section

The present study was designed to assess the effect of adrenaline on the plasma concentrations of fentanyl in mothers and umbilical vessels after epidural administration for caesarean section. Thirty patients undergoing elective caesarean section were allocated randomly into two groups. Group 1 (n = 16) received 100 microg fentanyl, 10 ml of 0.5% bupivacaine and 10 ml 2% lidocaine, while group II (n = 14) received 100 microg fentanyl, 10 ml of 0.5% bupivacaine with adrenaline 1:200 000, and 10 ml of 2% lidocaine with adrenaline 1:80 000. Blood samples were obtained from the maternal antecubital vein (MV) at various times up to 6 hours after epidural injection, and from umbilical vein (UV) and arteries (UA) at birth for determination of plasma fentanyl by radioimmunoassay. Fentanyl Cmax and Tmax in MV did not differ significantly between the two groups. In umbilical vessels, plasma fentanyl concentrations were comparable in the two groups: (0.12 +/- 0.08 ng ml(-1) and 0.13 +/- 0.08 ng ml(-1) in UV and 0.08 +/- 0.07 ng ml(-1) and 0.06 +/- 0.05 ng ml(1) in UA of groups I and II respectively). The maximum plasma concentration in UV was 0.24 ng ml(-1) in group I and 0.25 ng ml(-1) in group II. There was no significant correlation between umbilical vessel (vein or artery):MV ratio and dose to delivery interval and no difference between the two groups in Apgar score or umbilical cord pH.     

Comparison of articaine and bupivacaine/lidocaine for peribulbar anaesthesia by inferotemporal injection

Background. Articaine is a novel amide local anaesthetic witha shorter duration of action than prilocaine. Methods. In a randomized, double-blind study we compared theefficacy of 2% articaine with epinephrine 1:200 000 with a mixtureof 0.5% bupivacaine and 2% lidocaine with epinephrine 1:200000 for peribulbar anaesthesia in cataract surgery using a singleinferotemporal injection. Eighty-two patients were randomlyallocated to one of two groups to receive peribulbar anaesthesiawith 6–7 ml of articaine or a bupivacaine/lidocaine mixture.Both solutions contained hyaluronidase 30 iu ml^–1. Ocularmovement was scored at 2 min intervals up to 10 min, at theend of surgery and at time of discharge from hospital. Timeto readiness for surgery and any complications (proptosis, chemosis,pain) were recorded. Results. The articaine group demonstrated a rapid onset of peribulbarblock with mean time (SD) to readiness for surgery of 4.2 (4.5)min compared with 7.2 (5.7) min in the bupivacaine/lidocainegroup (P=0.0095). The block obtained in the articaine groupwas dense with eye movement scores at 2, 4, 6, 8 and 10 minall significantly reduced (P<0.01 at each interval). Therewas also a faster offset of the block in the articaine group(P=0.0009). There was no difference in incidence of minor complicationsbetween the groups. Conclusions. Two per cent articaine is safe and effective forperibulbar anaesthesia by inferotemporal injection and is asuitable alternative to the traditional mixture of 0.5% bupivacaineand 2% lidocaine. Br J Anaesth 2002; 88: 676–8