Spread Of Analgesia Research Articles

Epidural administration and analgesic spread: comparison of injection with catheters and needles.

This study was designed to investigate differences in epidural analgesic spread between catheter and needle injections in 48 patients with comparable physical characteristics. The spread of analgesia in the catheter injection group with a 0.24 ml.sec(-1) injection rate (n = 16) was 16.8 +/- 1.5 spinal segments and that in the needle injection group at the same injection rate (n = 16) was 12.5 +/- 1.8 spinal segments ( P < 0.01). Needle injection at the faster rate of 1.2 ml.sec(-1) (n = 16) produced a significantly greater spread of analgesia than with the 0.24 ml.sec(-1) rate through the needle (16.2 +/- 1.6 vs 12.5 +/- 1.8 spinal segments, P < 0.01). Thirteen of 16 patients receiving the fast needle injection complained of back compression or discomfort during the injection. The injection through an epidural catheter and the fast (1.2 ml.sec(-1)) injection through a needle produced extensive and equivalent epidural analgesic spread. However, because of patients discomfort with fast injection through the needle, the authors conclude that when using continuous epidural anesthesia, the initial injection of local anesthetic should be administered through the epidural catheter not the needle.

Effect of thoracic epidural etidocaine 1.5% on somatosensory evoked potentials, cortisol and glucose during cholecystectomy.

The effect of thoracic (T7-8) epidural etidocaine 1.5%, 9 ml, and continuous per- and postoperative epidural infusion of etidocaine 1.5%, 4 ml/h, on early (less than 500 ms) somatosensory evoked potentials (SEPs), and cortisol and glucose in plasma during cholecystectomy, was examined in ten patients. Spread of analgesia (pin-prick) was T3 (T1-T3) to L2 (T11-L3) 35 min after injection of etidocaine, and T3 (T2-T4) to T12 (T8-L4) 3 h after surgical incision (median (range)). Before operation, epidural etidocaine had no significant effects on peak-to-peak amplitude of SEPs to electrical stimulation at the L1, T10 or T6 dermatomal level (P greater than 0.09). SEPs were abolished in only two patients at T6, and no patient had SEPs abolished at T10 or L1. The plasma concentrations of cortisol and glucose were significantly increased 20 min after surgical incision and remained increased throughout the study. No correlation was found between the block-induced decrease in the peak-to-peak amplitude at T6 or T10 and increase in plasma cortisol, except for a negative correlation at T10 and the initial increase in cortisol (Rs = 0.72, P = 0.03). In conclusion, thoracic epidural administration of 9 ml of etidocaine 1.5% does not provide total afferent somatic blockade assessed by SEP and the stress response to cholecystectomy.

SYSTEMIC FENTANYL ENHANCES THE SPREAD OF SPINAL ANALGESIA PRODUCED BY LIGNOCAINE

Seventy-one patients undergoing transurethral prostatectomy under spinal anaesthesia were allocated randomly to one of four groups; fentanyl-naloxone (F-Nal), fentanyl-normal saline (F-NS), normal saline-naloxone (NS-Nal), and normal saline-normal saline (NS-NS) group. Twenty minutes after subarachnoid injection of hyperbaric lignocaine 100 mg, we tested the level of spinal analgesia (pinprick sensation) and administered i.v. either fentanyl 100 micrograms (F-Nal and F-NS groups) or normal saline 2 ml (NS-Nal and NS-NS groups). Ten minutes later, we assessed the new levels of analgesia and administered i.v. either naloxone 0.4 mg (F-Nal and NS-Nal groups) or normal saline 1 ml (F-NS and NS-NS groups). The level of sensory block was reassessed 10 min after the naloxone or normal saline treatment. Ten minutes after i.v. administration of fentanyl or normal saline, the level of analgesia increased in the F-Nal and F-NS groups by 3.98 and 3.78 cm, respectively, and differed significantly compared with the NS-Nal and NS-NS groups (both P less than 0.01). Forty minutes after spinal block, the decrease in analgesia in the F-Nal group (3.97 cm) differed significantly from that in the other groups (P less than 0.01). Systemic fentanyl enhanced the spread of analgesia. This enhancement was antagonized by naloxone.

Individual predictability of repeated spinal anaesthesia with plain 0.5% bupivacaine

To evaluate the individual predictability of spinal anaesthesia, 10 patients (3 women and 7 men) scheduled for control cystoscopy were studied twice within 9 months. Lumbar puncture was performed in the midline at the L2/3 interspace with the patient in the sitting position using plain 0.5% bupivacaine at 37 degrees C. A non-parametric Spearman test showed that, on the basis of the first block, the predictability of the cephalad analgesic spread of the second anaesthesia was high up to 60 min after injection. Thereafter the predictability decreased. The predictability of the motor blockade was generally low. Six patients obtained complete motor blockade twice; the remaining four, once.

COMPARATIVE STUDY OF THE EFFECTS OF AIR OR SALINE TO IDENTIFY THE EXTRADURAL SPACE

Fifty women in labour were allocated randomly to receive either air or saline to assist in the identification of the extradural space by the loss of resistance technique. A study volume of 4 ml of air or saline was used before 0.5% bupivacaine 8 ml and the spread of analgesia was followed for 30 min. The first segment blocked, time of onset, number of blocked segments and height of block were comparable in the two groups. At 30 min, there were eight patients with an unblocked segment in the air group, compared with two in the saline group (P less than 0.01). All unblocked segments were blocked subsequently by further doses of bupivacaine. We conclude that air is more likely than saline to produce unblocked segments in the initiation of extradural analgesia in labour.

Motor and Sensory Blockade after Epidural Injection of Mepivacaine, Bupivacaine, and Etidocaine???A Double-Blind Study

In a double-blind study of epidural anesthesia, 30 young volunteers were given either 2% mepivacaine (400 mg), 0.5% bupivacaine (100 mg), or 1.5% etidocaine (300 mg), all solutions containing epinephrine (1:200,000). The spread of analgesia was equal in the groups, whereas the longest duration was noted in the etidocaine and bupivacaine groups. With use of a method for determining muscle force, motor blockade during anesthesia was recorded quantitatively for hip flexion, knee extension, and plantar flexion of the big toe. Onset of motor blockade was significantly more rapid with etidocaine than with bupivacaine and mepivacaine. All subjects given etidocaine developed complete motor blockade, but with the other local anesthetics 5%-33% of the initial muscle force remained. The least motor blockade was found in the L5-S2 segment (plantar flexion of the big toe). The duration of maximal motor blockade varied between 60 min (mepivacaine) and 360 min (etidocaine). With each of the three local anesthetics, motor function returned simultaneously in the three muscle groups tested. Complete restoration of muscle function occurred significantly later for etidocaine (600 min) than for bupivacaine (360 min) and mepivacaine (180 min). With etidocaine, the motor blockade outlasted the sensory blockade by 150 min. The Bromage scale corresponded to the motor blockade only during the first half of the regression phase. Not until 1-3 h after attainment of Bromage grade 0 was the muscle force of all movements restored (90% of control values).

The Effect of Maternal Lateral Position or Position Change on Epidural Anesthesia and Plasma Bupivacaine Concentrations

Forty patients scheduled for elective cesarean section were studied. Epidural administration of 0.5% bupivacaine, 95-135 mg, was performed with the patients in right lateral decubitus position. In randomized order, half of the patients remained on the same side for 30 minutes. The other half were turned to the left lateral decubitus position for 30 minutes immediately after the epidural injection. Then all patients were turned to the left lateral “tilt” position for surgery. The spread of analgesia was tested by pinprick, and plasma bupivacaine concentrations were measured from mother and infant. The differences in the spread of anesthesia between the groups and sides (mean maximum cephalad spread was T4-T5) of the patients were small and not significant. Neither were there differences in plasma bupivacaine concentrations between the groups.

Individual predictability of repeated spinal anaesthesia with isobaric bupivacaine.

To evaluate the individual predictability of the spread of spinal anaesthesia, an analysis of 38 patients who had had at least two spinal blocks within 4 years was performed. All spinal blocks were done with the patients in the lateral position at the midline in the interspace LIII-IV, injecting 3 ml of isobaric 0.5% bupivacaine. Regression analysis showed that the predictability of the maximal analgesic spread of the second anaesthesia from the first anaesthesia was highly significant (P less than 0.0001). Therefore, if a higher or lower level of the block is required, another method for the forthcoming anaesthesia may be needed. The reasons for this phenomenon could not be clarified in this retrospective study.

Spread of local anesthetics in the epidural space.

The range of analgesic spread of lumbar epidural analgesia was investigated in 200 surgical patients (ASA class i＆ii)who were divided into three groups. There were 100 patients in group I and 50 patients each in groups ii＆iii. Epidural anesthesia was performed using 15 ml, 20 ml＆15 ml of 2% lidocaine for patients in group I, group ii and group iii respectively. Group iii consisted of 50 pregnant women who were specially selected while the patients in group I and group ii were randomly chosen. The segmental dose requirement(SDR)was plotted separately against age in years, and height in cm. A comparison of the differences among three groups was also made. Ageneral trend towards a smaller dose requirement was found with relation to an increase of age and a decrease in body height and pregnancy. The relationship between age, height and dose requirement revealed statistical significance. However, the segmental dose requirement was greatest in group ii and smallest in group I , both of which suggest that the segmental dose requirement increases with administration of larger doses. Therefore, the range of the epidural spread could not be predicted with merely controlling the dose administration. We found that it was difficult to obtain a reasonably wide analgesic field for young patients even by injecting larger doses of libocaine. In contrast, and unexpected wide range of analgesia could be developed with comparatively smaller doses of lidocaine in the elderly patients.

Analgesic dose-response relation in cervical epidural block.

The relationship between the age and the spread of analgesia from different epidural anesthetic doses was examined by studying analgesic dose responses in cervical epidural analgesia. Two different anesthetic doses (5 ml or 10 ml) of 2% mepivacaine were injected into the cervical epidural space at a constant pressure (80 mmHg) using an intravenous apparatus, and the spread of analgesia to pinprick was assessed. The significant correlation was found between the patient's age and the number of spinal segments blocked (5 ml : r = 0.8498, P < 0.01, 10 ml : r = 0.5988, P < 0.01). The inverse linear relationship was found between the patient's age and the segmental dose requirement (5 ml : r = -0.6754, P < 0.01, 10 ml : r = -0.5784, P < 0.01). Patients under 39 years of age showed a direct relationship between the dose injected and the number of spinal segments blocked, enabling prediction of the number of segments blocked with a given dose of local anesthetic. Doubling the epidural dose approximately doubled the number of spinal segments blocked. The analgesic dose-response relation in patients over 60 years of age differed from that in patients under 39 years of age and doubling the epidural dose did not double the number of spinal segments blocked. Progressively more extensive analgesia was obtained from a given dose of local anesthetic with advancing age. It was difficult to limit the extent of analgesia by injecting a smaller dose of local anaesthetic in the elderly.

Epidural pressure and its relation to spread of epidural analgesia.

The relationships between the epidural pressures following the injection of local anesthetic solution and the spread of epidural analgesia were investigated. In 46 patients, 15 ml of 2% mepivacaine was injected into the lumbar epidural space at a constant rate (1 ml/sec) using an electropowered syringe pump. Injection pressures and residual pressures were recorded and the spread of analgesia to pinprick was assessed. The changes of the epidural pressures during and following the injection of a volume of local anesthetic solution in old subjects were significantly smaller than those in young subjects (P < 0.05). The spread of analgesia closely correlated with the epidural pressures during and following the injection of local anesthetic solution. The most close correlation was found between the epidural pressure immediately after the completion of injection and the spread of analgesia (r = -0.5659, P < 0.001). In conclusion, the lower the terminal injection pressure and the residual pressures associated with higher age, the wider the spread of epidural analgesia.

Spinal anaesthesia with hyperbaric tetracaine: effect of age and body mass.

To discover the influence of age and body mass on spinal analgesia with hyperbaric tetracaine, 60 patients (17-82 years) were administered a subarachnoid injection of 15 mg tetracaine in 3 ml of 5% glucose. The patients were in the lateral position during the injection and in the supine position thereafter. The maximal spread of analgesia (mean T4, range T1-T11) did not correlate with age or body mass. Any variable studied was not significantly different for the different age groups. In 29 patients (48%) the block required supplementation with fentanyl or general anaesthesia (five patients). Tourniquet-induced pain occurred in eight patients (28% of patients with tourniquet). Decreases in systolic arterial blood pressure, greater than 30% of the preanaesthetic value, correlated with the level of analgesia and were more frequent in patients over 50 years (P less than 0.01). Severe hypotension and bradycardia with transient serious changes in QRS-complexes occurred in one patient (analgesia level, T3). In conclusion, 15 mg of hyperbaric tetracaine provided a relatively high sensory spinal blockade without correlating with age or body mass. Supplementation of analgesia during surgery was needed in almost half of the patient material.

Spread of epidural analgesia following a constant pressure injection--an investigation of relationships between locus of injection, epidural pressure and spread of analgesia.

(1) The spread of epidural analgesia following injection of 15 ml of 2% mepivacaine was 17.3 +/- 0.6, 14.3 +/- 0.4, and 13.3 +/- 0.7 spinal segments in cervical, thoracic, and lumbar epidural analgesia, respectively. The patient's age showed significant correlation with the spread of epidural analgesia in cervical (r = 0.5776, p < 0.001), thoracic (r = 0.3758, p < 0.01), and lumbar area (r = 0.8195, p < 0.001). The spread of cervical epidural analgesia was more caudad than cephalad (p < 0.05), but in lumbar epidural analgesia it was more cephalad than caudad (p < 0.05). There was no difference between the cephalad and caudad spread in thoracic epidural analgesia. (2) The epidural pressure immediately after injection of 15 ml of 2% mepivacaine into the lumbar epidural space at a constant pressure (80 mmHg) correlated to the patient's age (r = -0.5714, p < 0.001) and the spread of analgesia (r = -0.3904, p < 0.05). The lower epidural pressure associated with higher age, the wider spread of analgesia. There was no significant correlation between the residual pressure at 60 seconds and the age or the spread of analgesia.

The spread of caudal analgesia in children: a mathematical model.

A mathematical model correlating the spread of analgesia to the dose of local anaesthetic and to age or body weight was found analysing the data of 763 caudal blocks in children from age one day to twelve years. Two graphs have been plotted: (1) spread of analgesia, dose, age and (2) spread of analgesia, dose, weight. Both age and weight can be used as predictors to determine the desired level of analgesia, but weight is more useful in very young patients while age is a better guide in older children.

Barbotage and spinal anaesthesia The effect of barbotage on the spread of analgesia during isobaric spinal anaesthesia

Barbotage and spinal anaesthesia The effect of barbotage on the spread of analgesia during isobaric spinal anaesthesia

Restricted spread of analgesia following epidural blood patch.

Restricted spread of analgesia following epidural blood patch.

SPINAL ANAESTHESIA FOR CAESAREAN SECTION: The use of 0.5% bupivacaine

Subarachnoid anaesthesia was induced with 0.5% bupivacaine 2-3.5 ml in 33 women scheduled for elective Caesarean section. Three patients failed to develop adequate analgesia with bupivacaine but were managed satisfactorily with heavy cinchocaine. All the other patients developed adequate analgesia eventually. Since the spread of analgesia was uniquely dependent on posture a new hypothesis is presented to explain the distribution of intrathecal anaesthetic drugs in late pregnancy.

EFFECT OF POSTURE AND SOME C.S.F. CHARACTERISTICS ON SPINAL ANAESTHESIA WITH ISOBARIC 0.5% BUPIVACAINE

The effect of the sitting position (0, 2.5, 5.0 or 7.5 min), during and after the injection of 3 ml of 0.5% isobaric bupivacaine-HCl, on the segmental spread of spinal analgesia was studied in 40 patients. Ten patients injected in the lateral horizontal position acted as controls. The spread of analgesia was significantly greater in those who sat for 2.5 min or more compared with those who were immediately put in the supine position. Prolongation of the sitting time did not produce a higher analgesic block. The motor block was complete in all patients; its duration was significantly longer in the horizontal group than in all the sitting groups. There was no significant correlation between the different c.s.f. indices (pressure, protein and chloride ion concentration pH, and specific gravity) and the spinal block.

SPINAL ANALGESIA WITH HYPERBARIC BUPIVACAINE: EFFECTS OF VOLUME OF SOLUTION

The effects of 0.5% bupivacaine 1.5, 2 and 3 ml in 8% glucose was compared in a double-blind study involving 30 patients undergoing spinal analgesia. The time to the onset of maximum segmental spread of analgesia was approximately 15 min for all three volumes. Cephalad spread of analgesia was related to the volume used: 1.5 ml reached T10, 2 ml T8 and 3 ml T7. The duration of analgesia increased with increasing volume, 3 ml producing analgesia in T8-T12 for 1.5-2 h, and in the lumbar region for 2.5-3 h. Increasing the volume increased the extent of motor blockade and speeded up its onset. Significant decreases in arterial pressure were observed in the 2- and 3-ml groups. The changes in heart rate were moderate and not correlated with the amount of drug. Spinal headache occurred in two patients.

EFFECTS OF EXTRADURAL BLOCK: COMPARISON OF THE PROPERTIES, CIRCULATORY EFFECTS AND PHARMACOKINETICS OF ETIDOCAINE AND BUPIVACAINE

Five healthy, unmedicated male volunteers, aged 19-25 yr, participated in a double-blind, crossover study. Each subject received, on separate occasions and via a catheter placed at L2, 1.5% etiodocaine HCl20 ml with adrenaline 5 mug/ml, or 0.75% bupivacaine HCl 20 ml with adrenaline 5 mug/ml for extradural analgesia. In addition, in order to calculate the absorption rate of the local anaesthetic agent, each subject received on two further occasions etidocaine HCl 75 mg and bupivacaine HCl 75 mg respectively by i.v. infusion, over a period of 10 min. Spread of sensory analgesia to four segments above and below the site of injection was faster with etidocaine (13 +/- 3 min) (mean +/- SD) than with bupivacaine (22 +/- 8 min). Two-segment regression occurred later for bupivacaine (260 +/- 57 min) than for etidocaine (180 +/- 96 min). Caudal spread of analgesia was more extensive with etidocaine than with bupivacaine. The onset of motor blockade tended to be faster with etidocaine (5.8 +/- 3.0 min), than with bupivacaine (10.0 +/- 3.5 min); regression of motor blockade by one unit was longer with etidocaine (306 +/- 103 min) than bupivacaine (238 +/- 75 min). Sudomotor block occurred earlier with etidocaine (4.0 +/- 2.1 min) than bupivacaine (13.7 +/- 4.8 min). Significant changes in cardiac stroke work and stroke volume occurred. For etidocaine these measurements remained below control values for 120-210 min after injection. The mean maximum arterial plasma concentration of etidocaine was 1.52 +/- 0.64 mug/ml, at 14 +/- 2 min and of bupivacaine was 1.35 +/- 0.63 mug/ml, achieved at 20 +/- 4 min. The systemic absorption of both drugs occurred in a biphasic pattern with a fast and slow half-life of 0.3 and approximately 8 h respectively.