Br.J. Anaesth. (1978), 50, 171
EFFECTS OF ADRENALINE AND THE CONCENTRATION OF SOLUTION ON EXTRADURAL BLOCK WITH ETIDOCAINE F. P. BUCKLEY, D. G. LITTLEWOOD, B. G. COVIND AND D. B. SCOTT SUMMARY
The addition of adrenaline to a local anaesthetic solution reduces the plasma concentration of the drug and thus decreases its potential toxicity. In addition, a slower rate of absorption allows a greater uptake of local anaesthetic drug by nerves, an effect which should enhance the degree of block. Theoretically, a similar improvement in the frequency and duration of complete conduction blockade should be obtained by an increase in the total dose of drug administered. For the local anaesthetic agents of medium duration such as lignocaine, prilocaine and mepivacaine, the effects of adrenaline and the dosage of the drug appear to be well established (Crawford, 1964). Within limits an increase in dosage or the addition of adrenaline improves the quality and duration of anaesthesia. Studies of lignocaine for dental analgesia suggest that frequency of analgesia (number of successful blocks) can be improved more readily by the addition of adrenaline than by an increase in local anaesthetic concentration (Bjorn and Huldt, 1947). The data are more equivocal in the case of the longacting agents, bupivacaine and etidocaine. Lund, Cwik and Gannon (1974) demonstrated an increase in frequency and duration of adequate extradural block as the dose of etidocaine was increased from 100 to 300 mg. Similarly, more concentrated solutions of bupivacaine were shown to be more effective and last longer than dilute solutions (Littlewood et al., 1977) in extradural blocks for relief of pain in labour. Addition of adrenaline to etidocaine or bupivacaine for extradural blocks was of limited value for prolonging the duration of sensory analgesia (Moore et al., 1970; F. P. BUCKLEY, F.F.A.R.C.S.; D. G. LITTLEWOOD, F.F.A.R.C.S.; B. G. COVINO, M.D., PH.D.; D. B. SCOTT, M.D., M.R.C.P.E.,
F.F.A.R.C.S.; Department of Anaesthesia, Royal Infirmary, Edinburgh.
Bridenbaugh et al., 1974). The present study was carried out to determine the relative effects of the addition of adrenaline and variation in dosage of local anaesthetic on the duration and intensity of extradural block produced by etidocaine for lower abdominal surgery. METHODS
Forty adult females undergoing gynaecological operations through a sub-umbilical abdominal incision were studied (table I). Premedication comprised diamorphine 5 mg and atropine 0.6 mg given 1 h before operation. An extradural catheter was inserted into the second lumbar intervertebral space and (in most instances) left in situ for 24 h for the relief of pain after operation. Following the injection of 20 ml of the test solution of etidocaine, the patients were anaesthetized lightly with thiopentone followed by nitrous oxide 2 litre min" 1 , oxygen 1 litre min" 1 and halothane 0.5-1% using a circle system with carbon dioxide absorption. The extradural injection of etidocaine was given in a double-blind manner. The patients were allocated equally to four groups which received etidocaine 1% plain, 1% with adrenaline 1 : 200 000, 1.5% plain or 1.5% with adrenaline 1 : 200 000. During surgery, the block was assessed with regard to operative conditions, particularly the degree of muscle relaxation, and the development of arterial hypotension. To allow a quick recovery of consciousness at the completion of surgery the concentration of halothane was reduced as far as was compatible with the tolerance of an oral airway and face mask. In about half the patients this could be achieved without halothane. All the patients were responding to questions within a few minutes of the last skin
Downloaded from http://bja.oxfordjournals.org/ at University of Chicago on July 25, 2015
Forty patients allocated to four groups received extradural injections of etidocaine for the performance of lower abdominal surgery. Twenty millilitre of the 1 % or 1.5% solutions with or without adrenaline (1 : 200 000) was given in a double-blind manner. The addition of adrenaline to etidocaine did not significantly prolong the duration of analgesia, but it produced significantly more motor block. Etidocaine 1.5% caused significantly longer durations of analgesia and more motor block than the 1 % solution. The spread of sensory analgesia was similar with all four solutions of local anaesthetic agent.
BRITISH JOURNAL OF ANAESTHESIA
172
TABLE I. Age, height, weight and duration of surgery in the four groups of patients
Patient group (etidocaine concn)
No. of patients
Age
(yr)
Height (cm)
Weight (kg)
Duration of surgery (min)
10
41.9 + 3.8
159.7 ±2.3
62.4 ±2.3
55.0 ±3.4
10
41.2±1.9
158.6 ±1.6
72.1 ±4.1
67.5 ±4.4
10
38.6 ±1.6
157.7 ±1.5
66.3 ±3.4
62.0 ±5.9
10
36.7 + 2.9
158.3 ±2.9
58.2 ±3.9*
62.5 + 8.0
1% plain (200 mg) 1% with adrenaline (200 mg) 1.5% plain (300 mg) 1.5% with adrenaline (300 mg)
* Statistically significantly different from group receiving 1 % with adrenaline.
RESULTS
By analysis of variance there were no significant differences between the four groups of patients in terms of the means of age, height and duration of operation, but the group receiving etidocaine 1% + adrenaline 1 : 200 000 was significantly heavier than the group receiving 1.5% etidocaine with adrenaline (table I). In all patients an adequate extradural block was obtained as judged from the operating conditions. All the patients awoke promptly after surgery and there was no significant difference between the times to the first assessment in all the four groups (table II). The extent of the sensory block was similar in all four groups and on average it reached the level of the 5th-6th thoracic dermatome. The duration of complete analgesia (the time from
TABLE I I . Mean times from extradural injection to the first assessment (while extradural block was still effective), the second assessment (when abdominal pain appeared) and the third assessment (when further analgesia was required)
Mean time (min) to Patient group (drug concn)
1st assessment
2nd assessment
3rd assessment
1% plain (200 mg) 1% with adrenaline (200 mg) 1.5% plain (300 mg) 1.5% with adrenaline (300 mg)
88.5±5.3
167 + 27.0
261±33.0
93.5±7.5
164±16.0
240+17.3
96.0±6.5
180±13.5
306±22.8
94.3±7.2
191+26.9
318±30.0
injection to the second assessment) was greater in those patients receiving 1.5% etidocaine (185 min) than in those receiving 1% (165 min), but was not significantly affected by the addition of adrenaline. In all groups the extent of the sensory block present at the time of the second assessment was similar. The time from injection to the third assessment when further analgesia was required (the duration of clinically useful analgesia) was greater in those patients who received 1.5% etidocaine (312 min) than those receiving 1% (250 min), and this time was unaffected by the presence or absence of adrenaline. In assessing motor blockade statistically it was decided to group together scores of 0 and 1 (complete or almost complete paralysis) and 2 and 3 (slight or no paralysis) and perform a x2 test. This revealed (table III) that: (a) The frequency of profound motor block was always greater when adrenaline was added regardless
Downloaded from http://bja.oxfordjournals.org/ at University of Chicago on July 25, 2015
stitch. A neurological assessment was made 20-40 min after surgery, when the patient was fully co-operative and while the block was still fully effective. The extent of cutaneous analgesia was assessed by firm pinching with tissue forceps. Motor power in the lower limbs was quantified on a four-point scale: 0 = no movement, 1 = slight movement, 2 = moderate movement, 3 = normal movement. The movements tested were flexion and extension of the great toe, ankle, knee and hip. Following this initial assessment the patients were visited at 20-min intervals and asked if they had any pain (however slight) which required further analgesia. When pain appeared, a second assessment of the block was performed. When either the patient or the assessor considered that further analgesia was required, a third and final assessment was made. Such analgesia was obtained by an additional extradural injection or with an opiate.
173
EXTRADURAL BLOCK WITH ETIDOCAINE TABLE I I I . Mean scores of motor block in the four groups of patients. Eight movements in the lower limbs were assessed (extension and flexion at the hip, knee, ankle and great toe) and scored: 0 = no movement, 1 = slight movement, 2 = moderate movement and 3 = normal movement. In parentheses are the number of patients in each group who were substantially paralysed (0 or 1 for most movements) in the lower limbs
Mean score of eight movements at Patient group (drug concn)
2nd
3rd
assessment
assessment
0.5 (8)
1.1 (5)
2.2 (2)
0.2 (9)
0.6 (8)
2.0 (3)
0.1 (9)
0.8 (7)
2.3 (2)
0.0 (10)
0.4 (8)
1.4 (5)
t>
CJ
O
s
• 1 -
of the concentration of etidocaine. This was statistically significant at the first assessment with 1% etidocaine (/>
EFFECTS OF ADRENALINE AND THE CONCENTRATION OF SOLUTION ON EXTRADURAL BLOCK WITH ETIDOCAINE F. P. BUCKLEY, D. G. LITTLEWOOD, B. G. COVIND AND D. B. SCOTT SUMMARY
The addition of adrenaline to a local anaesthetic solution reduces the plasma concentration of the drug and thus decreases its potential toxicity. In addition, a slower rate of absorption allows a greater uptake of local anaesthetic drug by nerves, an effect which should enhance the degree of block. Theoretically, a similar improvement in the frequency and duration of complete conduction blockade should be obtained by an increase in the total dose of drug administered. For the local anaesthetic agents of medium duration such as lignocaine, prilocaine and mepivacaine, the effects of adrenaline and the dosage of the drug appear to be well established (Crawford, 1964). Within limits an increase in dosage or the addition of adrenaline improves the quality and duration of anaesthesia. Studies of lignocaine for dental analgesia suggest that frequency of analgesia (number of successful blocks) can be improved more readily by the addition of adrenaline than by an increase in local anaesthetic concentration (Bjorn and Huldt, 1947). The data are more equivocal in the case of the longacting agents, bupivacaine and etidocaine. Lund, Cwik and Gannon (1974) demonstrated an increase in frequency and duration of adequate extradural block as the dose of etidocaine was increased from 100 to 300 mg. Similarly, more concentrated solutions of bupivacaine were shown to be more effective and last longer than dilute solutions (Littlewood et al., 1977) in extradural blocks for relief of pain in labour. Addition of adrenaline to etidocaine or bupivacaine for extradural blocks was of limited value for prolonging the duration of sensory analgesia (Moore et al., 1970; F. P. BUCKLEY, F.F.A.R.C.S.; D. G. LITTLEWOOD, F.F.A.R.C.S.; B. G. COVINO, M.D., PH.D.; D. B. SCOTT, M.D., M.R.C.P.E.,
F.F.A.R.C.S.; Department of Anaesthesia, Royal Infirmary, Edinburgh.
Bridenbaugh et al., 1974). The present study was carried out to determine the relative effects of the addition of adrenaline and variation in dosage of local anaesthetic on the duration and intensity of extradural block produced by etidocaine for lower abdominal surgery. METHODS
Forty adult females undergoing gynaecological operations through a sub-umbilical abdominal incision were studied (table I). Premedication comprised diamorphine 5 mg and atropine 0.6 mg given 1 h before operation. An extradural catheter was inserted into the second lumbar intervertebral space and (in most instances) left in situ for 24 h for the relief of pain after operation. Following the injection of 20 ml of the test solution of etidocaine, the patients were anaesthetized lightly with thiopentone followed by nitrous oxide 2 litre min" 1 , oxygen 1 litre min" 1 and halothane 0.5-1% using a circle system with carbon dioxide absorption. The extradural injection of etidocaine was given in a double-blind manner. The patients were allocated equally to four groups which received etidocaine 1% plain, 1% with adrenaline 1 : 200 000, 1.5% plain or 1.5% with adrenaline 1 : 200 000. During surgery, the block was assessed with regard to operative conditions, particularly the degree of muscle relaxation, and the development of arterial hypotension. To allow a quick recovery of consciousness at the completion of surgery the concentration of halothane was reduced as far as was compatible with the tolerance of an oral airway and face mask. In about half the patients this could be achieved without halothane. All the patients were responding to questions within a few minutes of the last skin
Downloaded from http://bja.oxfordjournals.org/ at University of Chicago on July 25, 2015
Forty patients allocated to four groups received extradural injections of etidocaine for the performance of lower abdominal surgery. Twenty millilitre of the 1 % or 1.5% solutions with or without adrenaline (1 : 200 000) was given in a double-blind manner. The addition of adrenaline to etidocaine did not significantly prolong the duration of analgesia, but it produced significantly more motor block. Etidocaine 1.5% caused significantly longer durations of analgesia and more motor block than the 1 % solution. The spread of sensory analgesia was similar with all four solutions of local anaesthetic agent.
BRITISH JOURNAL OF ANAESTHESIA
172
TABLE I. Age, height, weight and duration of surgery in the four groups of patients
Patient group (etidocaine concn)
No. of patients
Age
(yr)
Height (cm)
Weight (kg)
Duration of surgery (min)
10
41.9 + 3.8
159.7 ±2.3
62.4 ±2.3
55.0 ±3.4
10
41.2±1.9
158.6 ±1.6
72.1 ±4.1
67.5 ±4.4
10
38.6 ±1.6
157.7 ±1.5
66.3 ±3.4
62.0 ±5.9
10
36.7 + 2.9
158.3 ±2.9
58.2 ±3.9*
62.5 + 8.0
1% plain (200 mg) 1% with adrenaline (200 mg) 1.5% plain (300 mg) 1.5% with adrenaline (300 mg)
* Statistically significantly different from group receiving 1 % with adrenaline.
RESULTS
By analysis of variance there were no significant differences between the four groups of patients in terms of the means of age, height and duration of operation, but the group receiving etidocaine 1% + adrenaline 1 : 200 000 was significantly heavier than the group receiving 1.5% etidocaine with adrenaline (table I). In all patients an adequate extradural block was obtained as judged from the operating conditions. All the patients awoke promptly after surgery and there was no significant difference between the times to the first assessment in all the four groups (table II). The extent of the sensory block was similar in all four groups and on average it reached the level of the 5th-6th thoracic dermatome. The duration of complete analgesia (the time from
TABLE I I . Mean times from extradural injection to the first assessment (while extradural block was still effective), the second assessment (when abdominal pain appeared) and the third assessment (when further analgesia was required)
Mean time (min) to Patient group (drug concn)
1st assessment
2nd assessment
3rd assessment
1% plain (200 mg) 1% with adrenaline (200 mg) 1.5% plain (300 mg) 1.5% with adrenaline (300 mg)
88.5±5.3
167 + 27.0
261±33.0
93.5±7.5
164±16.0
240+17.3
96.0±6.5
180±13.5
306±22.8
94.3±7.2
191+26.9
318±30.0
injection to the second assessment) was greater in those patients receiving 1.5% etidocaine (185 min) than in those receiving 1% (165 min), but was not significantly affected by the addition of adrenaline. In all groups the extent of the sensory block present at the time of the second assessment was similar. The time from injection to the third assessment when further analgesia was required (the duration of clinically useful analgesia) was greater in those patients who received 1.5% etidocaine (312 min) than those receiving 1% (250 min), and this time was unaffected by the presence or absence of adrenaline. In assessing motor blockade statistically it was decided to group together scores of 0 and 1 (complete or almost complete paralysis) and 2 and 3 (slight or no paralysis) and perform a x2 test. This revealed (table III) that: (a) The frequency of profound motor block was always greater when adrenaline was added regardless
Downloaded from http://bja.oxfordjournals.org/ at University of Chicago on July 25, 2015
stitch. A neurological assessment was made 20-40 min after surgery, when the patient was fully co-operative and while the block was still fully effective. The extent of cutaneous analgesia was assessed by firm pinching with tissue forceps. Motor power in the lower limbs was quantified on a four-point scale: 0 = no movement, 1 = slight movement, 2 = moderate movement, 3 = normal movement. The movements tested were flexion and extension of the great toe, ankle, knee and hip. Following this initial assessment the patients were visited at 20-min intervals and asked if they had any pain (however slight) which required further analgesia. When pain appeared, a second assessment of the block was performed. When either the patient or the assessor considered that further analgesia was required, a third and final assessment was made. Such analgesia was obtained by an additional extradural injection or with an opiate.
173
EXTRADURAL BLOCK WITH ETIDOCAINE TABLE I I I . Mean scores of motor block in the four groups of patients. Eight movements in the lower limbs were assessed (extension and flexion at the hip, knee, ankle and great toe) and scored: 0 = no movement, 1 = slight movement, 2 = moderate movement and 3 = normal movement. In parentheses are the number of patients in each group who were substantially paralysed (0 or 1 for most movements) in the lower limbs
Mean score of eight movements at Patient group (drug concn)
2nd
3rd
assessment
assessment
0.5 (8)
1.1 (5)
2.2 (2)
0.2 (9)
0.6 (8)
2.0 (3)
0.1 (9)
0.8 (7)
2.3 (2)
0.0 (10)
0.4 (8)
1.4 (5)
t>
CJ
O
s
• 1 -
of the concentration of etidocaine. This was statistically significant at the first assessment with 1% etidocaine (/>
