INCREMENTAL SPINAL ANAESTHESIA FOR ELECTIVE CAESAREAN SECTION: MATERNAL AND FETAL HAEMODYNAMIC EFFECTS

We have performed serial haemodynamic investigations in 20 womenundergoing elective Caesarean section under continuous spinalanaesthesia with a 32-gauge catheter with 0.5% heavy bupivacaine.Cardiac output was measured by Doppler and cross-sectional echocardiographyat the aortic valve. Doppler flow velocity waveforms were recordedalso from the umbilical artery. A block to 74 or above was achievedin all patients. The median dose of 0.5% bupivacaine administeredwas 2.0 ml (range 1.5–4.5 ml). Mean cardiac output increasedfrom 7 to 8 litre min^-1 after preloading with Ringer lactatesolution 1.5 litre and then remained unchanged after injectionof bupivacaine. Two subjects developed hypotension, althoughmean values of arterial pressure and umbilical artery pulsatilityindex did not change. The median umbilical artery pH was 7.27(range 6.98–7.32) and there was a significant correlationbetween pH and the maximum percentage decrease in cardiac output.The results suggest that continuous spinal anaesthesia is associatedwith greater haemodynamic stability than single bolus spinalinjection. (Br. J. Anaesth. 1993; 70: 634–638)     

MECHANISM OF EXTENSION OF SPINAL ANAESTHESIA BY EXTRADURAL INJECTION OF LOCAL ANAESTHETIC

We have examined the effect of extradural injection of 0.5%bupivacaine or normal saline on the progression of spinal anaesthesiain 28 patients undergoing Caesarean section. Three groups werestudied. Subarachnoid anaesthesia was established in all patients.Group A (n = 10), the control, received no extradural injectionfor 20 min. Group B (u= 9) received extradural bupivacaine 10ml and group C (n = 9) received extradural saline 10 ml 5 minafter the subarachnoid injection. Sensory levels were comparedat 5-min intervals and extension of the block was found to besimilar in groups B and C and significantly faster than thecontrol (P < 0.05). The quality of anaesthesia and incidenceof adverse effects was similar for all three groups. We concludethat the mechanism of extension of spinal anaesthesia by extraduralinjection of local anaesthesia is largely a volume effect. (Br.J. Anaesth. 1992; 69: 457–460) ^*Present address, for correspondence: Department of Anaesthetics,Freeman Hospital, High Heaton, Newcastle Upon Tyne NE7 7DN.     

SPINAL ANAESTHESIA WITH HYPOBARIC 0.19% OR PLAIN 0.5% BUPIVACAINE

Hypobaric 0.19% bupivacaine (plain 0.5% bupivacaine 3 ml + distilledwater 5 ml) was compared with 0.5% plain bupivacaine 3 ml forspinal anaesthesia in 29 healthy patients undergoing orthopaedicsurgery of the lower extremities. The solutions were injectedat the L3–4 interspace in 40 s, and patients were keptsitting for 2 min after injection. The mean maximal cephaladspread of sensory block was to the T1 segment (SD 3.6) and toT8 (4.1) in the hypobaric and plain bupivacaine groups, respectively(P < 0.0001). The study was interrupted after observing thesensory block of the 29th patient (hypobaric bupivacaine) spreadto C2 within 5 min of injection. In most patients, the hypobaricbupivacaine block affected the upper thoracic nerves, and inthree patients the cervical nerves also. The high levels ofblock were accompanied by marked hypotension. The extensivespread of the blocks makes this hypobaric spinal anaesthesiatechnique unsuitable for routine use.     

SPREAD OF SPINAL ANAESTHESIA FOR CAESAREAN SECTION IN SINGLETON AND TWIN PREGNANCIES

We have compared the spread of spinal anaesthesia in parturientswith singleton and those with twin pregnancies. Fifty-five unpremedicatedpatients with uncomplicated pregnancy scheduled for Caesareansection were allocated to two groups: group I = 35 singletonmothers; group II = 20 with twin pregnancy. Both groups receivedspinal anaesthesia with hyper baric bupivacaine 10 mg (2 mlof 0.5%). Mean birthweight was 3290 (SD 452) g and 5008 (495)g in groups I and II (combined birth weights), respectively.We found a statistically significant difference in onset andmaximal cephal-ad spread of spinal anaesthesia (group I median15, range 18–14; group II 13, range 16–12). Themechanisms of higher cephalad spread of spinal anaesthesia inparturients may be a decrease in cerebrospinal fluid volumesecondary to shunting of blood from the obstructed inferiorvena cava to the extradural venous plexus and increased nervesensitivity to local anaesthetics because of increased concentrationsof progesterone. The twin pregnancy group had heavier, largeruteri and greater daily production of progesterone. (Br. J.Anaesth. 1993; 70: 639–641)     

Spinal anaesthesia: comparison of plain ropivacaine 5 mg ml(-1) with bupivacaine 5 mg ml(-1) for major orthopaedic surgery

Background. Ropivacaine provides effective spinal anaesthesiafor total hip arthroplasty. This study was designed to comparethe efficacy and safety of plain ropivacaine with plain bupivacainefor spinal anaesthesia in patients undergoing total hip arthroplasty. Methods. Sixty-six patients, ASA I or II, were randomized toreceive an intrathecal injection of one of two local anaestheticsolutions. Group R (n=32) received 3.5 ml of ropivacaine 5 mgml^–1 (17.5 mg). Group B (n=34) received 3.5 ml of bupivacaine5 mg ml^–1 (17.5 mg). The onset and duration of sensoryblock at dermatome level T10, maximum upper and lower spreadof sensory block and the onset, intensity and duration of motorblock were recorded, as were safety data. Results. Onset of motor and sensory block was rapid with nosignificant differences between the two groups. The median timeof onset of sensory block at the T10 dermatome was 2 min (range2–5 min) in Group R and 2 min in Group B (range 2–9min). The median duration of sensory block at the T10 dermatomewas 3.0 h (range 1.5–4.6 h) in Group R and 3.5 h (2.7–5.2h) in Group B (P<0.0001). The median duration of completemotor block (modified Bromage Scale 3) was significantly shorterin the ropivacaine group compared with the bupivacaine group(2.1 vs 3.9 h, P<0.001). Conclusions. Intrathecal administration of either 17.5 mg plainropivacaine or 17.5 mg plain bupivacaine was well toleratedand an adequate block for total hip arthroplasty was achievedin all patients. A more rapid postoperative recovery of sensoryand motor function was seen in Group R compared with Group B. Br J Anaesth 2002; 89: 702–6     

SPINAL ANAESTHESIA WITH GLUCOSE-FREE 0.5% BUPIVACAINE: EFFECTS OF DIFFERENT VOLUMES

The effects of different volumes (1.5, 2, 3, and 4ml) of glucose-free0.5% bupivacaine used for spinal anaesthesia were compared in40 patients scheduled for urological surgery. The blocks wereperformed with the patients in the sitting position. The timeto maximum cephalad spread of analgesia varied between 13 and18.5 min. A significant difference was found in cephalad spreadbetween the 1.5-and 2-ml groups and the 3-and 4-ml groups. Theduration of analgesia increased, the time to complete motorblockade of the lower limbs decreased and the frequency of completemotor blockade increased with increasing volume. Spinal anaesthesiawith 3–4ml of glucose-free 0.5% bupivacaine proved satisfactoryfor transurethral resection of the prostate.     

EFFECT OF BARICITY ON SPINAL ANAESTHESIA WITH BUPIVACAINE

In a double-blind study of spinal anaesthesia with 0.5% bupivacaine3 ml with no glucose, 5% glucose or 8% glucose all three solutionsgave consistently good nerve blocks. The hyperbaric solutions(5% and 8% glucose) produced a greater cephalad spread and weresuitable for lower abdominal surgery, whereas the plain solution(no glucose) seldom affected the thoracic nerves. Cardiovascularchanges were more marked with the hyperbaric solutions but onlynecessitated treatment on two occasions. The duration of blockwas not affected by baricity and was in the range 140–160min.     

Haemodynamic changes during spinal anaesthesia with slow continuous infusion or single dose of plain bupivacaine

Forty elderly patients, scheduled for orthopaedic surgery of the hip or knee were studied. Twenty patients received a single-dose spinal anaesthesia with 3 ml of plain 0.5% bupivacaine (SDSA group). Twenty patients received continuous spinal anaesthesia using a 32- or 22-gauge catheter. A bolus of 1.0 ml of plain 0.5% bupivacaine was given to ten patients and 0.5 ml to another ten, continued by an infusion at a rate of 2 ml/h. The spread of analgesia and haemodynamic changes (central venous pressure, arterial pressures, need for sympathomimetic medication) were registered. The mean dose of bupivacaine was 2.9 ml (range 1.5-5 ml) in the CSA group (3.0 ml in the SDSA group). Eight patients in the CSA group needed medication for pain during surgery compared to five patients in the SDSA group (n.s.). The median level of pinprick analgesia at 60 min was T11 in the CSA and T6.5 in the SDSA group (P less than 0.01). The mean maximum decreases in CVP and MAP were quite similar in the CSA and SDSA group (2.1 vs 2.8 mmHg (0.3 vs 0.4 kPa) and 17 vs 21 mmHg (2.3 vs 2.8 kPa), respectively) (n.s.). Six patients in the SDSA group and four patients in the CSA group needed sympathomimetic medication. It is concluded that titration of bupivacaine for spinal anaesthesia caused only minor haemodynamic changes which were similar to those after single-dose spinal bupivacaine.     

Comparison of ropivacaine 0.5% (in glucose 5%) with bupivacaine 0.5% (in glucose 8%) for spinal anaesthesia for elective surgery

Background. Hyperbaric solutions of ropivacaine have been usedsuccessfully to provide spinal anaesthesia. This study was designedto compare the clinical efficacy of hyperbaric ropivacaine withthat of the commercially available hyperbaric preparation ofbupivacaine. Methods. Forty ASA grade I–II patients undergoing lower-abdominal,perineal or lower-limb surgery under spinal anaesthesia wererecruited and randomized to receive ropivacaine 5 mg ml^–1(with glucose 50 mg ml^–1), 3 ml or bupivacaine 5 mg ml^–1(with glucose 80 mg ml^–1), 3 ml. The level and durationof sensory block, intensity and duration of motor block, andtime to mobilize and micturate were recorded. Patients wereinterviewed 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 groupsin mean time to onset of sensory block at T10 (ropivacaine 5min; bupivacaine 2 min; P<0.005), median maximum extent (ropivacaineT7; bupivacaine T5; P<0.005) and mean duration of sensoryblock at T10 (ropivacaine 56.5 min; bupivacaine 118 min; P=0.001).Patients receiving ropivacaine mobilized sooner (ropivacainemean 253.5 min; bupivacaine 331 min; P=0.002) and passed urinesooner (ropivacaine mean 276 min; bupivacaine 340.5 min; P=0.01)than those receiving bupivacaine. More patients in the bupivacainegroup required treatment for hypotension (>30% decrease insystolic pressure; P=0.001). Conclusions. Ropivacaine 15 mg in glucose 50 mg ml^–1 providesreliable spinal anaesthesia of shorter duration and with lesshypotension than bupivacaine. The recovery profile for ropivacainemay be of interest given that more surgery is being performedin the day-case setting. Br J Anaesth 2003; 90: 304–8     

EFFECT OF ADRENALINE ON EXTRADURAL ANAESTHESIA AND PLASMA BUPIVACAINE CONCENTRATIONS DURING CAESAREAN SECTION

The effect of adrenaline on the efficacy of extradural blockand plasma bupivacaine concentrations was investigated in womenundergoing elective (n = 40) and emergency (n = 40) Caesareansection. Patients were randomly allocated within these two groupsto receive 0.5% bupivacaine 20 ml either plain or with adrenaline1 in 200000, as a single fractionated extradural injection.The elective plain group needed significantly more supplementaryanalgesia compared with the other three groups (P <0.05).In the elective group, plasma bupivacaine concentrations weresignificantly lower in the subgroup receiving extradural adrenalinethan in the plain subgroup. This effect was not observed whencomparing only those who received bupivacaine 100 mg. In theemergency group, there were no significant differences in plasmabupivacaine concentrations between the plain and adrenalinesubgroups. Maximum plasma concentrations correlated significantly(P < 0.0001) with dose of bupivacaine (mg kg^–1). Itis concluded that extradural adrenaline does not usefully reducesystemic absorption of 0.5% bupivacaine, but may improve itsefficacy in extradural anaesthesia for elective Caesarean section.     

EFFECTS OF POSTURE ON THE SPREAD OF SPINAL ANAESTHESIA WITH ISOBARIC 0.75% OR 0.5% BUPIVACAINE

In a double-blind study the effects of posture on the the spreadof 3 ml of isobanc bupivacaine 5 and 7 Smgml^–1 were comparedafter intrathecal injection in 40 patients undergoing orthopaedicsurgery. Three milhhtre of isobanc bupivacaine 7 5 mgml^–1administered with the patient in a sitting position during andfor 2.5 mm after injection produced the highest spread of analgesia(T4) Horizontal posture, and the smaller dose in both positions,resulted in spread of analgesia to T7-8. Motor block in thelegs was good in all cases. Horizontal posture at the time ofinjection resulted in the longest mean duration of analgesiaand motor block, although there was no statistically significantdifference in mean rimes between the groups The longest meanduration of pin-prick analgesia (329 ± 23 min) was inthe patients injected in the horizontal posture with bupivacaine7.5 mgml^–1. The course of anaesthesia and recovery wereuneventful in all patients.     

CONTINUOUS EXTRADURAL ANAESTHESIA IN CHILDREN: Clinical and Haemodynamic Implications

This study reports the experience of a department of paediatricanaesthesia with 234 continuous extradural anaesthetics performedin 229 children over a 15-month period. Fifty-nine of the childrenwere aged 0–2 yr, 71 were aged 2–8 yr and 104 wereolder than 8 yr. The surgical procedures lasted more than 60min (mean 150±10.6 min); all were carried out under lightgeneral anaesthesia. Technical procedure and difficulties arereported. The only local anaesthetic agent used was bupivacainewith or without adrenaline. Mean initial dosage was 0.75 mlkg^–1 for children weighing less than 20 kg and 1 ml/10cm of height for children taller than 100 cm. Using 0.25% bupivacainemean times until a further injection were 92.0±2.0 minfor bupivacaine with adrenaline and 71.0±2.5 min forbupivacaine without adrenaline (P < 0.001). A much longerduration of analgesia was found for younger children using thesolution with adrenaline. A haemodynamic study was performedin 74 unpremedicated children (ASA l; aged 0–2 yr (n =15), 2–8 yr (n = 26) and older than 8 yr (n = 35)). Beforeinduction of anaesthesia, heart rate (HR) was significantlyincreased in the youngest children, but no significant changewas found for systolic arterial pressure (SAP). After extraduralanaesthesia with 0.25% bupivacaine with adrenaline 1:200000,minimal changes in HR or SAP occurred in children younger than8 yr; in those older than 8 yr a significant decrease in bothHR and SAP was observed. Changes in SAP were at their maximum25 min after the extradural block and changes in HR were notstatistically significant before the 25th min following injectionof local anaesthetic. The catheter remained in place in 155children for postoperative analgesia, mainly for the first 48h.     

AN OPEN STUDY OF ROPIVACAINE IN EXTRADURAL ANAESTHESIA

Ropivacaine 0.5%, 0.75% and 1.0% was investigated in an openstudy of extradural anaesthesia in three groups of 15 patientsundergoing urological or orthopaedic surgery. Following a testdose of 3 ml of 1.0% lignocaine with 1:200 000 adrenaline, ropivacaine20 ml was given in incremental doses over 4 min via a lumbarextradural catheter. The onset time for analgesia was shortin all groups: T12 was blocked 4–6 min after the end ofthe injection of ropivacaine. The maximum segmental level wassignificantly higher in the 0.75% and the 1.0% groups (T2) thanin the 0.5% group (T5). Complete motor block was obtained inseven, four and nine patients in the 0.5%, 0.75% and the 1.0%groups, respectively. Duration of algesia increased with increasingconcentration of ropivacaine: mean duration of analgesia was203 and 266 min at T10 and 253 and 314 min at L5 for the 0.5and 1 % solutions, respectively. Mean duration of complete motorblock was 94 and 192 min for the same solutions. Analgesia wassatisfactory for surgery in all patients except for one in the0.75% group. Hypotension was experienced by three, seven andthree patients in the 0.5%, 0.75% and 1.0% groups, respectively.Bradycardia occurred in seven patients and was associated withhypotension in five. Backache was experienced after operationby four patients, and three patients complained of a brief mildheadache. No late adverse events were seen.     

Rate of injection through whitacre needles affects distribution of spinal anaesthesia

A prospective, randomized, double-blind study was performedto investigate whether altering the rate of injection of localanaesthetic through a Whitacre needle had any effect on thespinal block achieved. Twenty patients scheduled for electiveurological surgery under spinal anaesthesia received an injectionof 3 ml of 0.5% plain bupivacaine either by hand (fast)over 10 s (18 ml min^–1) or by infusionpump (slow) over 3 min (1 ml min^–1). Allpatients were in the sitting position both during insertionof the spinal needle and for 3 min after the start of spinalinjection, and they then changed to the supine position. Theslow injection group achieved peak sensory block earlier, aftera median interval of 20 (95% confidence interval 12.5–30) minvs 30 (22.5–45) min (P<0.05) for the fast group. Thelevel of peak sensory block was similar: T3.5 (T2–T4.5)vs T4 (T1.5–T6.5). The time to lowest mean arterial pressureoccurred earlier in the slow group, at 10 (8 to 18) vs 20 (15–31) min(P<0.05). Duration of the motor block was shorter in theslow group: 180 (152–242) vs 270 (225–300). We concludethat a slow spinal injection of plain bupivacaine results ina block of more rapid onset and recovery. Br J Anaesth 2001; 86: 245–8     

EFFECT OF LATE POSTURE CHANGE ON THE LEVEL OF SPINAL ANAESTHESIA WITH PLAIN BUPIVACAINE

We studied 40 patients, 18–60 yr, undergoing orthopaedicsurgery of the lower limb under spinal anaesthesia. A midilnelumbar puncture was performed in the L3–4 interspace usinga 27-gaugeneedle with the patient in the lateral horizontalposition. Plain bupivacaine 3 ml at room temperature was injected.The cephalad level of an algesia was assessed by pinprick 60min after injection of local anaesthetic, at the end of surgeryand again after the patient was moved into bed. All patientshad a segmental level of the block of L1-T5 at the beginningof the study. The upper half of the patient's body was thentilted to a 30° head-up position. Segmental spread was subsequentlyassessed by pinprick at 5-min intervals for 30 min. In six ofthe 40 patients (15%), increased cephalad spread of spinal analgesiaoccurred. The mean time from induction of spinal anaesthesiawas shorter in these six patients (mean 92 min, range 80–115min) than in the patients whose block did not change or wasdecreasing during the 30-min test (mean 119 mm, range 83–210min) (P <0.05). We conclude that the patient should remainin the supine horizontal position until recovery from the spinalblock. (Br. J. Anaesth. 1993; 71: 807–809)     

SEGMENTAL LEVELS OF ANAESTHESIA FOLLOWING THE EXTRADURAL INJECTION OF 0.75% BUPIVACAINE AT DIFFERENT LUMBAR SPACES IN ELDERLY PATIENTS

Segmental anaesthesia levels were determined in 80 elderly patientsfollowing the extradural injection of 0.75° bupivacaine15ml at four separate lumbar interspaces. Mean levels were T11in the L5-Sl group, T7 in the L4-5, T5 in L3-4 and T3 in theL2-3 group (P<0.001). Varying the lumbar interspace at whichthe extradural anaesthesia is performed is recommended as ameans of adjusting the levels of anaesthesia for different surgicalprocedures.     

Spinal anaesthesia with 0.5% hyperbaric bupivacaine in elderly patients: effects of duration spent in the sitting position

Sixty patients, aged 65–84 yr, undergoing minor urologicalsurgery under spinal anaesthesia remained sitting for 2 (group1, n=15), 5 (group 2, n=15), 10 (group 3, n=15), or 20 (group4, n=15) min after completion of the subarachnoid administrationof 3 ml of a 0.5% hyperbaric bupivacaine solution. They werethen placed in the supine position. Analgesia levels were assessedbilaterally using pinprick. Motor block was scored using a 12-pointscale. Systolic and diastolic arterial pressures and heart ratewere also recorded. Twenty minutes after the injection the upperanalgesia levels were lower (P<0.05) in group 4 (median T9.0)than in the groups 1–3 (medians T6.6–T8.5). Thehighest obtained levels (medians T5.7–T8.0) did not differbetween the groups, but occurred later (P<0.05) in group4 (median 35 min) than in groups 1–3 (medians 19–24min). There were no significant differences in the maximum degreeof motor block or haemodynamic changes between the four studygroups. Br J Anaesth 2001; 87: 738–42     

COMPARISON OF BUPIVACAINE AND ETIDOCAINE IN EXTRADURAL BLOCKADE

In a randomized, double-blind study, 40 female patients underwentmajor gynaecological surgery with extradural anaesthesia providedby 0.75% bupivacaine, 0.75% bupivacaine with adrenaline 5µgml^–1,1.5%etidocaine or 1.5% etidocaine with adrenaline 5 µg ml^–1,20ml in each case. In all patients the resultant blockade wassuitable for intra-abdominal pelvic surgery. Mean maximum spreadof analgecia was around T3/4 with all four drugs. Onset of sensoryand motor block was more rapid following etidocaine than followingbupivacaine. The addition of adrenaline increased the speedof onset of sensory block. Patients receiving etidocaine hada denser motor blockade than those receiving bupivacaine, andthe addition of adrenaline led to an increase in the densityof the motor blockade. There were no differences in the durationsof motor blockade. Objective measurements of the duration ofsensory blockade showed that there were no differences betweenthe drugs and that the addition of adrenaline increased theduration of blockade. However, pain returned sooner followingetidocaine than bupivacaine, and the additive effect of adrenalinewas to increase this period of subjective analgesia.     

SENSITIVITY, SPECIFICITY AND PREDICTIVE VALUE OF THE SENSATION OF WARMTH AS A METHOD OF DETECTING INADVERTENT SUBARACHNOID INJECTION OF LOCAL ANAESTHETIC WHEN PERFORMING EXTRADURAL BLOCKS

In order to test if the rate of onset of sensation of warmthin the legs after the injection of 0.5% bupivacaine might discriminatebetween subarachnoid and extradural injection, 150 urologicalpatients were allocated randomly to receive either spinal anaesthesiawith isobaric (IS) or hyperbaric (HS) 0.5% bupivacaine, or extraduralanaesthesia with isobaric 0.5% bupivacaine. The volume of thelocal anaesthetic for spinal anaesthesia and for the extraduraltest dose was 3–4 ml. The patients were asked to reportat once if they had a sensation of warmth in the legs duringor after injection of local anaesthetic. The mean time to thesensation of warmth was significantly shorter in the spinalgroups (80 (SEM 10) s in IS and 76 (8.0) s in HS) than in theextradural group (558 (38) s). However, six patients in theIS and two in the HS group had no sensation of warmth.     

SPINAL ANAESTHESIA WITH PLAIN 0.5% BUPIVACAINE AT 19 {degrees}C AND 37 {degrees}C

Forty-five men aged 50–80 yr undergoing urological surgeryunder spinal anaesthesia were allocated randomly to three groups.All patients received 0.5% plain bupivacaine 3 ml injected atthe L2–3 interspace. The temperature of the solution ingroup 1 was 19 °C, in groups 2 and 3 37 °C. In groups1 and 2 the injection was performed with the patient sitting;in group 3 the patient was in a lateral horizontal position.Spread of block, intensity of motor block and cardiovascularstability were measured. Warming the solution from 19 °Cto 37 °C before spinal injection with the patient in thesitting position did not significantly affect these variables.However, the extent of analgesia was reduced significantly whenthe 37 °C solution was injected with the patient in thelateral horizontal compared with the sitting position.