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UNBLOCKED SEGMENTS ESI EPIDURAL ANALGESIA FOR RELIEF OF PAIN IN LABOUR
Brit. J. Anaesth. (1972), 44, 676
UNBLOCKED SEGMENTS ESI EPIDURAL ANALGESIA FOR RELIEF OF PAIN IN LABOUR P. R. BROMAGE SUMMARY
Epidural analgesia is "spotty" in a small proportion of cases. One or more dermatomes may escape blockade and remain sensitive in an otherwise satisfactory field of analgesia. These unblocked segments are usually confined to one side, and are seldom bilateral, and they are most often seen in obstetrical patients. The phenomenon of patchy extradural anaesthesia was discussed by Bryce-Smith in 1954 with special reference to caudal anaesthesia. Shanks (1968) and Usubiaga, Dos Reis and Usubiaga (1970) have also considered the occurrence of spotty anaesthesia in spinal epidural blockade. More recently Ducrow (1971) recorded the incidence of unblocked segments in 920 obstetrical patients, using bupivacaine as the analgesic agent. In Ducrow's series the overall incidence of spotty or unilateral anaesthesia was 8.2 per cent, and the condition was persistent in 2.04 per cent in spite of repeated doses of bupivacaine. For practical purposes, a "spotty" regional anaesthetic is a failed anaesthetic. The patient experiences pain, and if the sensory input is sufficient the quality of agony is just as acute as if no anaesthesia existed in the neighbouring segments. Since local anaesthetics differ in their penetrance and efficiency, it is important for the anaesthetist to have some knowledge of the shortcomings or advantages of the various drugs he may choose from. This study compares the incidence of "spotty" or missed segments occurring among six different local anaesthetic agents, in a personally conducted series PHILIP
R.
BROMAGE,
M.B., F.F.A.RX.S.,
Royal Victoria
Hospital, Montreal, and Department of Anaesthesia, McGill University, Montreal, Canada.
of 433 continuous epidural anaesthetics for relief of pain in labour and vaginal delivery. METHOD
Epidural anaesthesia was induced when labour was established and painful. No other form of analgesia was employed. Epidural puncture was made at the 2nd lumbar interspace with a 17-gauge Tuohy needle. An air-filled syringe was used to identify the epidural space by the loss-of-resistance technique. The patients were usually in the right lateral position, with slight or moderate flexion of the spine. After identification of the epidural space two-thirds of the initial epidural dose was injected through the epidural needle. A vinyl catheter was then quickly inserted for a distance of about 4 cm in a cephalad direction, and the needle withdrawn. The patient was then rapidly turned on to the opposite side, and the remaining one-third of the initial dose injected through the catheter. Six different agents were tested: amethocaine, bupivacaine, and the hydrochloride and carbonated salts of lignocaine and prilocaine. Two concentrations were tested for each agent; the distribution of cases is shown in table I. Adrenaline was added freshly to all the test solutions, in a concentration of 1/200,000. Table II shows the dose schedule observed for the various solutions. The upper and lower margins of the analgesic segments were determined by pin-prick at frequent intervals, and a segment-time diagram of the analgesic area was constructed for each patient. The situation was reviewed if satisfactory analgesia was not established in 10-15 min. Failure of the block to rise to the 11th thoracic segment or above was
Downloaded from http://bja.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on May 28, 2015
The incidence of missed, unblocked segments during continuous epidural analgesia for relief of pain in labour and vaginal delivery was studied in 433 patients. Six different local anaesthetic agents were tested: the carbonated salts of lignocaine and prilocaine, and the hydrochloride salts of lignocaine, prilocaine, bupivacaine and amethocaine. The incidence of painful or unblocked segments ranged from 1 per cent with carbonated lignocaine, to 12.8 per cent with amethocaine hydrochloride, and it was four times higher with lignocaine hydrochloride than with carbonated lignocaine.
UNBLOCKED SEGMENTS IN EPIDURAL ANALGESIA TABLE I. Distribution of local anaesthetic agents employed in 433 continuous epidural blocks for relief of pain in labour. Agent
Hydrochloride salts Lignocaine
40 54 32 32
1%
43 32 30 32 56 35 31 16
•
2% 1% 2% 0.25% 0.5% 0.25% 0.5%
Prilocaine Bupivacaine Amethocaine
Total
433
Local anaesthetic dose regime for relief of pain in labour (ml).
40 54
0 1
0 0
1.06
32 32
0 1
1 0
3.12
43 32
1 2
0 0
4.0
30 32
4 2
1 1
12.5
56 35
5 2
1 0
8.8
31 16
2 1
2 1
12.8
2nd stage
1st stage
2%
2% HCI 4 _ a 8 HCI CO, . , CO 2 0.25% 4-8
Lignocaine-CO, 1% ' 2% Prilocaine-CO, 1% 2% Lignocaine HC1 1% 2% Prilocaine HC1 1% 2% Bupivacaine HC1 0.25% 0.5% Amethocaine HC1 0.25% 0.5%
Prilo. HCI
13 12
4-6
6-14
5-12
3-6
6-12
5-9
0.5% 4-6
0.25% 6-14
0. 5% 5-12
corrected by a further increment of local anaesthetic injected up the epidural catheter, but the initial adjustment was not recorded as a "missed segment" if the outcome was successful. A missed or unblocked segment was defined as: (1) failure of the block to rise to the 11th thoracic dermatome on both sides, after an adequate initial dose of local anaesthetic, or (2) appreciation of pain in one or more segments below the 11th thoracic dermatome. Completely unilateral anaesthesia was attributed to misplacement of the epidural catheter, and if correctable by replacing the catheter, was not counted among the "missed segment" group. Unblocked segments that remained resistant to repeated incremental injections of local anaesthetic were counted as "persistent unblocked segments". RESULTS
The incidence of unblocked segments is shown in table III, and a graphic comparison is made in figure 1. The highest proportion of unblocked segments was found with amethocaine and prilocaine hydrochloride, and the lowest with carbonated lignocaine. The incidence of unblocked segments was
11 YvCh Persistent 10
2 9
I
1 Temporary
Bupiv.
I
I• I 7 6
Tetr.
i
1
Lido.
CO 2
Q.
HCI 4
Prilo.
3 2
Lido.
1
FIG. 1. Incidence of unblocked or painful segments in continuous epidural analgesia for relief of pain in labour. Lido = Lidocaine (lignocaine) Prilo = Prilocaine (Citanest) Bupiv. = bupivacaine (Marcain) Tetr. = tetracaine (amethocaine)
about four times higher with the hydrochloride salts of lignocaine and prilocaine than with the carbonated salts. The carbonated local anaesthetics seem to possess the potency required to overcome resistant unblocked segments. For example: CASE N O . 35C
In this patient analgesia was induced by a colleague, and this case is not included in the main series. Leftsided anaesthesia persisted in spite of three successive
Downloaded from http://bja.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on May 28, 2015
1% 2% 1% • 2%.
in 433 delivery.
Temporary Persistent Total n unblocked unblocked incidence (%)
Agent
Prilocaine
Lignocaine Prilocaine Lignocaine Prilocaine Amethocaine
TABLE III. Incidence of unblocked segments cases of continuous epidural analgesia for vaginal
No.
Carbonated salts Lignocaine
TABLE II.
677
678
BRITISH JOURNAL OF ANAESTHESIA
doses of 2% mepivacaine, with the right side downwards. Without altering the position of the epidural catheter, 3 ml of 2% carbonated lignocaine was injected. In 10 min anaesthesia spread to the unblocked side, and anaesthesia became symmetrical, reaching to the 10th thoracic dermatome on both sides.
Downloaded from http://bja.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on May 28, 2015
recommended as a suitable agent for obstetrical anaesthesia. Bupivacaine also had a high incidence of unblocked segments in this series. However, it should be remembered that bupivacaine possesses the peculiar advantage of producing very little motor paralysis in relation to the degree of sensory DISCUSSION anaesthesia (Bromage, 1969), and for this reason it The cause of unblocked segments is still speculative. deserves special consideration for relief of pain in Bryce-Smith (1954) suggested that a missed seg- labour and vaginal delivery. ment could be attributed to failure of the anaestheWith the orthodox hydrochloride salts of lignotic solution to escape from the intervertebral foracaine and prilocaine the incidence of unblocked segmen in sufficient amount to bathe an adequate ments was four times greater than with the carbolength of the paravertebral nerve. The existence of nated solutions. The 2% carbonated solutions caused epidural membranes and adhesions has been invoked an excessive degree of motor block, but the 1% to account for the limited spread of blockade, and carbonated solutions appeared to have an ideal X-ray evidence tends to support this idea (Shanks, balance of controlled power and efficiency, producing 1968). Usubiaga, Dos Reis and Usubiaga (1970) uniform dependable anaesthesia without excessive postulated that sensory block might be ineffective motor involvement. if the catheter tip came to lie in the anterior instead These findings give strong support to the view of the posterior part of the epidural space. At term the epidural veins are distended beyond their normal that carbonated local anaesthetics should be given diameter, and this may be an additional factor a wider clinical trial, particularly in obstetrical limiting the spread of diffusion of local anaesthetics anaesthesia. during labour. REFERENCES Whatever the cause, it is apparent from the data Bromage, P. R. (1969). An evaluation of bupivacaine in epidural analgesia for obstetrics. Canad. Anaesth. Soc. that solutions with high penetrance are more likely J., 16, 46. to produce efficient, homogenous and satisfactory Bryce-Smith, R. (1954). The spread of solutions in the blockade, than drugs with relatively poor penetrating extradural space. Anaesthesia, 9, 201. qualities. Ducrow, M. (1971). The occurrence of unblocked segments during continuous lumbar epidural analgesia In regional anaesthesia for obstetrics there is a for relief of pain in labour. Brit. J. Anaesth., 43, 1172. very narrow margin between success and failure, Shanks, C. A. (1968). Four cases of unilateral epidural and "partial" successes scarcely exist. The mother analgesia. Brit. J. Anaesth., 40, 999. either experiences complete relief or she experiences Shnider, S. M., and Way, E. L. (1968). Plasma levels of lidocaine (Xylocaine) in mother and newborn pain if one or more segments escape blockade. following obstetrical conduction anesthesia: clinical There is nothing in between. Motor blockade must applications. Anesthesiology, 29, 951. be avoided as far as possible, so that labour can Usubiaga, J. E., Dos Reis, A., and Usubiaga, L. E. (1970). Epidural misplacement of catheters and proceed normally with unimpaired expulsive powers. mechanisms of unilateral blockade. Anesthesiology, 32, And finally, for the sake of the baby, dosage must 158. be kept to a minimum since the newborn's physical performance is impaired by high circulating conSEGMENTS NON-BLOQUES LORS DE centrations of local anaesthetics (Shnider and Way, L'ANALGESIE EPIDURALE POUR LE 1968). SOULAGEMENT DES DOULEURS DU TRAVAIL These clinical constraints impose a severe test, SOMMAIRE both upon details of technique and upon the drugs L'incidence de segments manques, non-bloques durant selected. Therefore, if technical details can be stan- l'analgesie epidurale continue pour le soulagement des de travail et de l'accouchement par voie vaginale, dardized, the resulting success or failure rates douleurs a ete etudiee chez quatre cent et trente trois patients. Six represent a reasonably valid scale for ranking the agents differents d'anssthisie locale ont ete testes; les carbonates de lignocaine et prilocaine et les hydrochlorures efficiency of the agents that are used. de lignocaine, prilocaine, bupivacaine et amethocaine. From table II and figure 1 it is clear that the L'incidence de segments douloureux ou non-bloques incidence of failure (in terms of unblocked seg- variait de 1 pourcent avec le carbonate de lignocaine a 12,8 pourcent avec l'hydrochlorure d'amethocaine, et ments) varies widely between the different agents etait quatre fois plus eleve avec Phydrochlorure de lignotested. Amethocaine scores poorly, and it is not caine qu'avec le carbonate de lignocaine.
UNBLOCKED SEGMENTS IN EPIDURAL ANALGESIA NICHTBLOCKIERTE SEGMENTE BEI DER EPIDURALANALGESIE ZUR SCHMERZBEKAMPFUNG WAHREND DER ENTBINDUNG
679
SEGMENTOS NO BLOQUEADOS EN LA ANALGESIA EPIDURAL PARA ALIVIAR EL DOLOR DEL PARTO RESUMEK
Die Haufigkeit ausgesparter, nichtblockierter Segmente unter einer kontinuierlichen Epiduralanasthesie zur Schmerzbekampfung wahrend der Wehen und der vaginalen Entbindung wurde bei 433 Patientinnen untersucht. Sechs verschiedene Lokalanasthetica wurden gepriift; die Carbonatsalze von Lignocain und Prilocain sowie die Hydrochloridsalze von Lignocain, Prilocain, Bupivacain und Amethocain. Die Haufigkeit des Aufretens schmerzempfindlicher, oder nichtblockierter Segmente schwankte zwischen 1% bei Lignocaincarbonat und 12,8% bei Amethocainhydrochlorid und war bei dem Hydrochlorid des Lignocains viermal grosser als bei Lignocaincarbonat.
Fue estudiada en cuatrocientas treinta y tres pacientes la frecuencia de segmentos perdidos no bloqueados durante la analgesia epidural continua para aliviar el dolor del parto y nacimiento vaginal. Fueron probados seis anestesicos locales diferentes: las sales carbonatadas de lignocaina y prilocaina, y las sales hidrocloradas de lignocaina, prilocaina, bupivacaina y ametocaina. La frecuencia de segmentos dolorosos o no bloqueados vario entre el 1 por ciento con lignocaina carbonatada hasta el 12,8 por ciento con clorhidrato de ametocaina, y fue cuatro veces mayor con clorhidrato de lignocaina que con lignocaina carbonatada.
6th INTERNATIONAL ANAESTHESIA POSTGRADUATE COURSE Vienaa, May 21 to 25, 1973 This Course is devoted to the subject of "The activities of the anaesthetist beyond the operating theatre" and consists of practical and theoretical lectures. Enquiries please address to: Frl. E. Maurer, c/o Wiener Medizinische Akademie, Alser Strasse 4, A-1090 Wien, Austria.
Downloaded from http://bja.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on May 28, 2015
ZUSAMMENFASSUNG
UNBLOCKED SEGMENTS ESI EPIDURAL ANALGESIA FOR RELIEF OF PAIN IN LABOUR P. R. BROMAGE SUMMARY
Epidural analgesia is "spotty" in a small proportion of cases. One or more dermatomes may escape blockade and remain sensitive in an otherwise satisfactory field of analgesia. These unblocked segments are usually confined to one side, and are seldom bilateral, and they are most often seen in obstetrical patients. The phenomenon of patchy extradural anaesthesia was discussed by Bryce-Smith in 1954 with special reference to caudal anaesthesia. Shanks (1968) and Usubiaga, Dos Reis and Usubiaga (1970) have also considered the occurrence of spotty anaesthesia in spinal epidural blockade. More recently Ducrow (1971) recorded the incidence of unblocked segments in 920 obstetrical patients, using bupivacaine as the analgesic agent. In Ducrow's series the overall incidence of spotty or unilateral anaesthesia was 8.2 per cent, and the condition was persistent in 2.04 per cent in spite of repeated doses of bupivacaine. For practical purposes, a "spotty" regional anaesthetic is a failed anaesthetic. The patient experiences pain, and if the sensory input is sufficient the quality of agony is just as acute as if no anaesthesia existed in the neighbouring segments. Since local anaesthetics differ in their penetrance and efficiency, it is important for the anaesthetist to have some knowledge of the shortcomings or advantages of the various drugs he may choose from. This study compares the incidence of "spotty" or missed segments occurring among six different local anaesthetic agents, in a personally conducted series PHILIP
R.
BROMAGE,
M.B., F.F.A.RX.S.,
Royal Victoria
Hospital, Montreal, and Department of Anaesthesia, McGill University, Montreal, Canada.
of 433 continuous epidural anaesthetics for relief of pain in labour and vaginal delivery. METHOD
Epidural anaesthesia was induced when labour was established and painful. No other form of analgesia was employed. Epidural puncture was made at the 2nd lumbar interspace with a 17-gauge Tuohy needle. An air-filled syringe was used to identify the epidural space by the loss-of-resistance technique. The patients were usually in the right lateral position, with slight or moderate flexion of the spine. After identification of the epidural space two-thirds of the initial epidural dose was injected through the epidural needle. A vinyl catheter was then quickly inserted for a distance of about 4 cm in a cephalad direction, and the needle withdrawn. The patient was then rapidly turned on to the opposite side, and the remaining one-third of the initial dose injected through the catheter. Six different agents were tested: amethocaine, bupivacaine, and the hydrochloride and carbonated salts of lignocaine and prilocaine. Two concentrations were tested for each agent; the distribution of cases is shown in table I. Adrenaline was added freshly to all the test solutions, in a concentration of 1/200,000. Table II shows the dose schedule observed for the various solutions. The upper and lower margins of the analgesic segments were determined by pin-prick at frequent intervals, and a segment-time diagram of the analgesic area was constructed for each patient. The situation was reviewed if satisfactory analgesia was not established in 10-15 min. Failure of the block to rise to the 11th thoracic segment or above was
Downloaded from http://bja.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on May 28, 2015
The incidence of missed, unblocked segments during continuous epidural analgesia for relief of pain in labour and vaginal delivery was studied in 433 patients. Six different local anaesthetic agents were tested: the carbonated salts of lignocaine and prilocaine, and the hydrochloride salts of lignocaine, prilocaine, bupivacaine and amethocaine. The incidence of painful or unblocked segments ranged from 1 per cent with carbonated lignocaine, to 12.8 per cent with amethocaine hydrochloride, and it was four times higher with lignocaine hydrochloride than with carbonated lignocaine.
UNBLOCKED SEGMENTS IN EPIDURAL ANALGESIA TABLE I. Distribution of local anaesthetic agents employed in 433 continuous epidural blocks for relief of pain in labour. Agent
Hydrochloride salts Lignocaine
40 54 32 32
1%
43 32 30 32 56 35 31 16
•
2% 1% 2% 0.25% 0.5% 0.25% 0.5%
Prilocaine Bupivacaine Amethocaine
Total
433
Local anaesthetic dose regime for relief of pain in labour (ml).
40 54
0 1
0 0
1.06
32 32
0 1
1 0
3.12
43 32
1 2
0 0
4.0
30 32
4 2
1 1
12.5
56 35
5 2
1 0
8.8
31 16
2 1
2 1
12.8
2nd stage
1st stage
2%
2% HCI 4 _ a 8 HCI CO, . , CO 2 0.25% 4-8
Lignocaine-CO, 1% ' 2% Prilocaine-CO, 1% 2% Lignocaine HC1 1% 2% Prilocaine HC1 1% 2% Bupivacaine HC1 0.25% 0.5% Amethocaine HC1 0.25% 0.5%
Prilo. HCI
13 12
4-6
6-14
5-12
3-6
6-12
5-9
0.5% 4-6
0.25% 6-14
0. 5% 5-12
corrected by a further increment of local anaesthetic injected up the epidural catheter, but the initial adjustment was not recorded as a "missed segment" if the outcome was successful. A missed or unblocked segment was defined as: (1) failure of the block to rise to the 11th thoracic dermatome on both sides, after an adequate initial dose of local anaesthetic, or (2) appreciation of pain in one or more segments below the 11th thoracic dermatome. Completely unilateral anaesthesia was attributed to misplacement of the epidural catheter, and if correctable by replacing the catheter, was not counted among the "missed segment" group. Unblocked segments that remained resistant to repeated incremental injections of local anaesthetic were counted as "persistent unblocked segments". RESULTS
The incidence of unblocked segments is shown in table III, and a graphic comparison is made in figure 1. The highest proportion of unblocked segments was found with amethocaine and prilocaine hydrochloride, and the lowest with carbonated lignocaine. The incidence of unblocked segments was
11 YvCh Persistent 10
2 9
I
1 Temporary
Bupiv.
I
I• I 7 6
Tetr.
i
1
Lido.
CO 2
Q.
HCI 4
Prilo.
3 2
Lido.
1
FIG. 1. Incidence of unblocked or painful segments in continuous epidural analgesia for relief of pain in labour. Lido = Lidocaine (lignocaine) Prilo = Prilocaine (Citanest) Bupiv. = bupivacaine (Marcain) Tetr. = tetracaine (amethocaine)
about four times higher with the hydrochloride salts of lignocaine and prilocaine than with the carbonated salts. The carbonated local anaesthetics seem to possess the potency required to overcome resistant unblocked segments. For example: CASE N O . 35C
In this patient analgesia was induced by a colleague, and this case is not included in the main series. Leftsided anaesthesia persisted in spite of three successive
Downloaded from http://bja.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on May 28, 2015
1% 2% 1% • 2%.
in 433 delivery.
Temporary Persistent Total n unblocked unblocked incidence (%)
Agent
Prilocaine
Lignocaine Prilocaine Lignocaine Prilocaine Amethocaine
TABLE III. Incidence of unblocked segments cases of continuous epidural analgesia for vaginal
No.
Carbonated salts Lignocaine
TABLE II.
677
678
BRITISH JOURNAL OF ANAESTHESIA
doses of 2% mepivacaine, with the right side downwards. Without altering the position of the epidural catheter, 3 ml of 2% carbonated lignocaine was injected. In 10 min anaesthesia spread to the unblocked side, and anaesthesia became symmetrical, reaching to the 10th thoracic dermatome on both sides.
Downloaded from http://bja.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on May 28, 2015
recommended as a suitable agent for obstetrical anaesthesia. Bupivacaine also had a high incidence of unblocked segments in this series. However, it should be remembered that bupivacaine possesses the peculiar advantage of producing very little motor paralysis in relation to the degree of sensory DISCUSSION anaesthesia (Bromage, 1969), and for this reason it The cause of unblocked segments is still speculative. deserves special consideration for relief of pain in Bryce-Smith (1954) suggested that a missed seg- labour and vaginal delivery. ment could be attributed to failure of the anaestheWith the orthodox hydrochloride salts of lignotic solution to escape from the intervertebral foracaine and prilocaine the incidence of unblocked segmen in sufficient amount to bathe an adequate ments was four times greater than with the carbolength of the paravertebral nerve. The existence of nated solutions. The 2% carbonated solutions caused epidural membranes and adhesions has been invoked an excessive degree of motor block, but the 1% to account for the limited spread of blockade, and carbonated solutions appeared to have an ideal X-ray evidence tends to support this idea (Shanks, balance of controlled power and efficiency, producing 1968). Usubiaga, Dos Reis and Usubiaga (1970) uniform dependable anaesthesia without excessive postulated that sensory block might be ineffective motor involvement. if the catheter tip came to lie in the anterior instead These findings give strong support to the view of the posterior part of the epidural space. At term the epidural veins are distended beyond their normal that carbonated local anaesthetics should be given diameter, and this may be an additional factor a wider clinical trial, particularly in obstetrical limiting the spread of diffusion of local anaesthetics anaesthesia. during labour. REFERENCES Whatever the cause, it is apparent from the data Bromage, P. R. (1969). An evaluation of bupivacaine in epidural analgesia for obstetrics. Canad. Anaesth. Soc. that solutions with high penetrance are more likely J., 16, 46. to produce efficient, homogenous and satisfactory Bryce-Smith, R. (1954). The spread of solutions in the blockade, than drugs with relatively poor penetrating extradural space. Anaesthesia, 9, 201. qualities. Ducrow, M. (1971). The occurrence of unblocked segments during continuous lumbar epidural analgesia In regional anaesthesia for obstetrics there is a for relief of pain in labour. Brit. J. Anaesth., 43, 1172. very narrow margin between success and failure, Shanks, C. A. (1968). Four cases of unilateral epidural and "partial" successes scarcely exist. The mother analgesia. Brit. J. Anaesth., 40, 999. either experiences complete relief or she experiences Shnider, S. M., and Way, E. L. (1968). Plasma levels of lidocaine (Xylocaine) in mother and newborn pain if one or more segments escape blockade. following obstetrical conduction anesthesia: clinical There is nothing in between. Motor blockade must applications. Anesthesiology, 29, 951. be avoided as far as possible, so that labour can Usubiaga, J. E., Dos Reis, A., and Usubiaga, L. E. (1970). Epidural misplacement of catheters and proceed normally with unimpaired expulsive powers. mechanisms of unilateral blockade. Anesthesiology, 32, And finally, for the sake of the baby, dosage must 158. be kept to a minimum since the newborn's physical performance is impaired by high circulating conSEGMENTS NON-BLOQUES LORS DE centrations of local anaesthetics (Shnider and Way, L'ANALGESIE EPIDURALE POUR LE 1968). SOULAGEMENT DES DOULEURS DU TRAVAIL These clinical constraints impose a severe test, SOMMAIRE both upon details of technique and upon the drugs L'incidence de segments manques, non-bloques durant selected. Therefore, if technical details can be stan- l'analgesie epidurale continue pour le soulagement des de travail et de l'accouchement par voie vaginale, dardized, the resulting success or failure rates douleurs a ete etudiee chez quatre cent et trente trois patients. Six represent a reasonably valid scale for ranking the agents differents d'anssthisie locale ont ete testes; les carbonates de lignocaine et prilocaine et les hydrochlorures efficiency of the agents that are used. de lignocaine, prilocaine, bupivacaine et amethocaine. From table II and figure 1 it is clear that the L'incidence de segments douloureux ou non-bloques incidence of failure (in terms of unblocked seg- variait de 1 pourcent avec le carbonate de lignocaine a 12,8 pourcent avec l'hydrochlorure d'amethocaine, et ments) varies widely between the different agents etait quatre fois plus eleve avec Phydrochlorure de lignotested. Amethocaine scores poorly, and it is not caine qu'avec le carbonate de lignocaine.
UNBLOCKED SEGMENTS IN EPIDURAL ANALGESIA NICHTBLOCKIERTE SEGMENTE BEI DER EPIDURALANALGESIE ZUR SCHMERZBEKAMPFUNG WAHREND DER ENTBINDUNG
679
SEGMENTOS NO BLOQUEADOS EN LA ANALGESIA EPIDURAL PARA ALIVIAR EL DOLOR DEL PARTO RESUMEK
Die Haufigkeit ausgesparter, nichtblockierter Segmente unter einer kontinuierlichen Epiduralanasthesie zur Schmerzbekampfung wahrend der Wehen und der vaginalen Entbindung wurde bei 433 Patientinnen untersucht. Sechs verschiedene Lokalanasthetica wurden gepriift; die Carbonatsalze von Lignocain und Prilocain sowie die Hydrochloridsalze von Lignocain, Prilocain, Bupivacain und Amethocain. Die Haufigkeit des Aufretens schmerzempfindlicher, oder nichtblockierter Segmente schwankte zwischen 1% bei Lignocaincarbonat und 12,8% bei Amethocainhydrochlorid und war bei dem Hydrochlorid des Lignocains viermal grosser als bei Lignocaincarbonat.
Fue estudiada en cuatrocientas treinta y tres pacientes la frecuencia de segmentos perdidos no bloqueados durante la analgesia epidural continua para aliviar el dolor del parto y nacimiento vaginal. Fueron probados seis anestesicos locales diferentes: las sales carbonatadas de lignocaina y prilocaina, y las sales hidrocloradas de lignocaina, prilocaina, bupivacaina y ametocaina. La frecuencia de segmentos dolorosos o no bloqueados vario entre el 1 por ciento con lignocaina carbonatada hasta el 12,8 por ciento con clorhidrato de ametocaina, y fue cuatro veces mayor con clorhidrato de lignocaina que con lignocaina carbonatada.
6th INTERNATIONAL ANAESTHESIA POSTGRADUATE COURSE Vienaa, May 21 to 25, 1973 This Course is devoted to the subject of "The activities of the anaesthetist beyond the operating theatre" and consists of practical and theoretical lectures. Enquiries please address to: Frl. E. Maurer, c/o Wiener Medizinische Akademie, Alser Strasse 4, A-1090 Wien, Austria.
Downloaded from http://bja.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on May 28, 2015
ZUSAMMENFASSUNG