486
P a r a v e r t e b r a l S y m p a t h e t i c Block for Labor
Anesth Analg 57-486-490,197X
Lumbar Sympathetic Block with Bupivacaine: Analgesia for Labor RAMON V. MEGUIAR, LT, MC, USNR" A. SCOTT WHEELER, LCDR, MC, USNRt Portsmouth, Virginia$
Forty primigravidas were given a bilateral paravertebral lumbar sympathetic block during stage I of labor using 10 cc of 0.5% bupivacitine and 1:200,000 epinephrine on each side. Good analgesia was obtained in 38 patients with maximal effect 7.5 -f. 3 minutes after hlockade. Maternal mean blood pressure and pulse were unchanged, fetal well-being was not compromised, and labor progressed rapidly. Twenty-eight patients delivered prior to resolution of the block, while in the remaining 12 patients pain returned before delivery with analgesia having lasted 283 t 103 minutes. In the former 28 patients, analgesia for expulsion was provided by pudendal, saddle block, or infiltrat ion analgesia, whereas continuous lumbar epidural or caudal analgesia was utilized when
I?
ARAVERTEBRAL lumbar svmpathetic block was first described for use in obstetrics in 1927.1 However, the mechanism of action was not greatly appreciated until 1933, when ('leland demonstrated that uterine and cervical visceral afferent sensory fibers join the sympathetic chain at L2-3.' Later authors reported the ease of administration of para\ ertebral sympathetic block, its reliability for producing analgesia during labor, and a low incidence of maternal side effects:' In addition, Hunter used tokodynamometry to demonstrate acceleration of the first stage of labor in 20 of 39 parturients given sympathetic blocks.' Significant detrimental fetal effects have not been reported."
Although sympathetic-block analgesia is
remission preceded s t a g e 11. I n comparison t o continuous lumbar epidural analgesia, t h e procedure is technically more difficult, generally more painful, and requires a second anesthetic for delivery. It is concluded that bilateral paravertebral lumbar sympathetic block with bupivacaine provides reliable analgesia of long duration with a low incidence of undesirable side effects. However, its primary usefulness is in cases where continuous lumbar epidural analgesia is refused or contraindicated. Key \Vords-ANESTHESIA, obstetric. ANESTHETIC TECHNICS, sympathetic block. SYMPATHETIC NERVOUS SYSTEM, paravertebral sympathetic block. ANESTHETICS, local, bupivacaine.
efficacious and relatively safe, its usefulness has been precluded by the short duration of action obtained with local anesthetic agents available in the past. We have re-examined the technic using the long-acting local anesthetic bupivacaine hydrochloride. Our results corroborate those cited before, except that in contradistinction to the earlier reports, the duration of analgesia with 0.5% bupivacaine was usually long enough. This report describes clinical features of this anesthetic technic in 40 parturients.
METHODS Forty primigravidas with a mean age of 21.7 years and a mean gestation of 40 weeks received a bilateral paravertebral lumbar
"Resident in Obstetrics and Gynecology ;Stafl Anesthesiologist. Present address: Assistant Professor of Anesthesia, Bowman Gray School of Medicine. Winston-Salem, North Carolina 27103
:Ikpartments of Anesthesiology and Obstetrics and Gynecology, Naval Regional Medical Center, Portsmouth, Virqinia 23508 This study has been sponsored and supported by the Bureau of Medicine and Surgery, Clinical Investigation Program No. CR 08-7-45. 'The opinions or assertions contained herein are those of the authors a n d are not to br construed a s official or reflecting viens of the Department of the Navy or of the Department of Defense. Addiess reprint requests to Dr. Wheeler. Section of Obstetric nnd Gynecologic Anesthesia, Forsyth Memorial Hospital. 3333 SIlas Creek Parkway, Winston-Salem, North Carolina 27103. Accepted for publication: May 4, 1978
Anesth Analg :a7:486-490. 1978
Meguiar and Wheeler
487
sympathetic block during the first stage of tem from zero to 3, with zero representing labor. They were all ASA I patients8 and no analgesia and 3 representing complete had unremarkable gestational histories ex- uterine analgesia. Scores of 2 or 3 were cept for a single patient at 28 weeks’ gesta- considered to represent satisfactory analgetion with premature rupture of membranes sia. The time from injection of the local and early chorioamnionitis. Thirty-three pa- anesthetic to complete cervical dilatation tients were in the active phase of labor, as was noted, as was the time to recurrence of described by Friedman,Qwhen cervical dila- abdominal or back discomfort. Anesthesia tation was 4 to 5 cm with uterine contrac- for delivery was provided by pudendal, lotions occurring every 3 minutes and lasting cal-infiltration, or saddle-block analgesia. more than 30 seconds. The remaining 7 pa- Continuous lumbar epidural or caudal tients were in the latent phase or had a dys- Flocks were administered when the symfunctional labor pattern. All patients under- pathetic block remitted prior to the second went continuous electronic monitoring of stage of labor. Neonatal Apgar scores were fetal heart rates and uterine contractions assigned at 1 and 5 minutes. Data were (Corometrics type I11 B) for at least 30 analyzed with Student’s t-test for paired minutes before sympathetic block. Fetal samples. Significance was assumed when heart rates were measured with scalp elec- p20%, reduction in madegree cephalad direction to identify the ternal blood pressure occurred in 2 patients, second lumbar transverse process. The nee- both of whom were in the supine position for dle was then withdrawn to the skin and vaginal examinations. The blood pressure redirected beneath and 4.5 cm beyond the returned to normal upon resumption of the transverse process with a 10-degree mesiad lateral position. The mean increase in skin angle. If the vertebral body was encoun- temperature of the lower extremity, 4.5 c tered, the needle was withdrawn and redi- 1.8 C, was achieved within 25 minutes. rected laterally 5 to 10 degrees. Ten milliAt the time of blockade, the mean cervilitres of 0.5% bupivacaine hydrochloride cal dilatation of the 33 patients in active with 1:200,000 epinephrine were injected on labor was 4.8 2 0.9 cm. There was no each side. change in the frequency of contractions, and Patients were then returned to the lateral the mean time from block to complete cerposition. The time from injection of the vical dilatation was 158 ? 92 minutes. In second side to maximum or complete uter- addition, mean fetal heart rates were not ine analgesia was noted. Frequency of con- changed, and a significant alteration in the tractions, maternal blood pressure and pulse, baseline variability of fetal heart rates was fetal heart rate, and skin temperature of not seen in any patient. However, 1 patient the lower extremity were recorded every 5 required cesarean section for sustained fetal minutes after blockade. Quality of maternal bradycardia occurring 150 minutes after the analgesia was ascertained by a scoring sys- block. This event was believed by the at-
488
Paravertebral Sympathetic Block for Labor
tending obstetrician to be secondary to umbilical-cord compression and unrelated to sympathetic block. This infant’s Apgar scores were 8 and 9. Apgar scores for the entire group were 7.9 ? 1.3 and 9.0 2 0.8 at 1 and 5 minutes, respectively.
DISCUSSION Pain in the first stage of labor is largely due to distention of the cervix and lower uterine segment. The sensory fibers from the uterus and cervix travel with sympathetic nerves passing through the posterior cervical plexus Frankenhauser’s plexus) and the superior hypogastric plexus to enter the sympathetic chain a t L2-3. They then ascend in the paravertebral sympathetic chain to enter the spinal cord via the white rami communicantes a t the 11th and 12th thoracic levels.’.’ 1 Therefore, a conduction blockade of the sympathetic chain at the 2nd lumbar vertebra prevents transmission of afferent sensory impulses from the cervix and uterus and will provide analgesia during labor.? r, The primary limitation to lumbar sympathetic block for labor has in the past been ihe short duration of analgesia. Shumacker et a1 obtained analgesia with 0.5% tetracaine, but the maximum duration was 4 hours.:: Various concentrations of procaine and piperocaine yield an average duration of 90 minutes;: lidocaine produces analgesia for 90 to 180 minutes.” We utilized bupivacaine because of its long duration of action, i t s reliable sensory blockade, and its appsrently low placental transfer.’:’-lT Our results show that 0.5% bupivacaine with 1:200,000 epinephrine ensures a more acceptable duration of analgesia, for the mean analgesia time of 283 minutes far exceeds that of all previously studied agents. The effect of epinephrine on duration of sympathetic blockade with bupivacaine is questionable. In epidural blockade, epinephrine decreases the rate of maternal absorption of bupivacaine but does not prolong its effect.’’ We used epinephrine with the intention of lessening t h e absorption and placental transfer of bupivacaine, not to prolong its duration of action. Notable features of bupivacaine sympathetic block were the rapid onset of action and high success rate of analgesia. Failure to obtain suitable analgesia in 2 of 40 patients compares favorably with a success rate of “over 90”/0,” as noted by Bonica.” Since this technic produces no motor block-
Anc,sth Antilg
,>7.4M~4WI,1978
ade, patients can move about freely and can “bear down” effectively in the second stage of labor. In addition, the progression of labor is rapid, a s evidenced by the mean block to complete cervical dilatation time of 158 minutes seen in the 33 patients in active labor. This finding compares favorably with the duration of labor noted after continuous lumbar epidural analgesia with 0.5% bupivacaine.’:’ Moreover, adverse effects of the technic on fetal heart rate were not observed. Thus, bupivacaine sympathetic block would apparently be more advantageous than paracervical block anesthesia, which has frequently been associated with fetal bradycardia.’” 2 1 Bonica quotes a 15 to 20% incidence of “mild hypotension” after lumbar sympathetic blocks.” In our study, the 5% incidence of maternal hypotension, which responded rapidly to position change, is most acceptable. Our incidence of hypotension may be lower because patients were hydrated before blockade and because they were placed in the lateral position after blockade. Although bilateral paravertebral sympathetic block can usually be completed within 10 minutes, it is generally more painful and technically more difficult than lumbar epidural analgesia. In addition, the use of sympathetic block for labor necessitates the ndministration of a second anesthetic for delivery. Continuous lumbar epidural analgesia not only provides good analgesia for vaginal delivery but also ensures successful anesthesia for cesarean section when necessary. Although the duration of analgesia with bupivacaine sympathetic block exceeds that observed after single-dose epidural blockade with bupivacaine,’!’ 1 2 the duration of analgesia was still insufficient in 30% of our patients. This finding substantiates our usual preference for continuous epidural anesthesia, especially for pitocininduced labors, which have unpredictable durations. A s a result, our use of continuous lumbar epidural anesthesia and sympathetic blocks for labor has approximated a ratio of 10 to 1. We use sympathetic blockade primarily when epidural analgesia is contraindicated or refused. For example, one patient in this study underwent lumbar fusion 4 years prior to admission, making epidural blockade impossible. Two patients were nurses who refused spinal and epidural anesthesia but consented to sympathetic blockade. While
Anesth Analg 57:486-490, 1978
not allowing the lumbar epidural block with 0.5% other mechanism stage I of labor.
Meguiar and Wheeler
flexibility of continuous anesthesia, sympathetic bupivacaine provides anto achieve analgesia for
Perineal analgesia for stage I1 is usually provided a€ter paravertebral sympathetic block with pudendal or saddle-block anesthesia. Pudendal blockade is preferred for spontaneous deliveries, whereas saddle block is utilized when forceps are indicated. We encourage our obstetricians to initiate puc’,endal anesthesia in the labor room when perineal discomfort becomes disconcerting.
It is noteworthy that total spinal anesthesia has been reported in 2 patients receiving lumbar sympathetic blockade.23 Meticulous attention to detail should prevent this complication. Inadvertent penetration into the retroperitoneal space with subsequent hemorrhage has been reported in 3 patients who received a series of paravertebral blocks for treatment of peripheral vascular disease.24 This complication was not mentioned in the literature we reviewed of lumbar sympathetic blocks for labor. Our incidence of intravascular needle placement is approximately 2%; hemorrhagic sequellae have not occurred. Furthermore, symptoms of maternal local anesthetic toxicity have not been encountered to date (in 325 cases). Due to possible increases in uterine contractility,7 caution should be exercised regarding the use of this anesthetic technic in parturients with tetanic labor patterns or with evidence oi uteroplacental insufficiency. In conclusion, bilateral paravertebral lumbar sympathetic blockade with 0.5% bupivacaine and 1:200,000 epinephrine is an effective anesthetic technic for labor, yielding a high incidence of good uterine analgesia. The duration of sensory blockade with bupivacaine greatly exceeds the duration of blockade seen with other local anesthetic agents. In our study, uterine analgesia persisted throughout delivery in 70% of our primigravid patients. Labor progresses well, and the block is not commonly associated with maternal or fetal complications. However, hypotension can occur, and blood presLure must be monitored. Since continuous lumbar epidural analgesia is less painful, technically less difficult, and can be extended to provide analgesia for vaginal or abdominal delivery, bupivacaine sympathetic blockade is primarily utilized when continuous lumbar epidural analgesia is contraindicated.
489
ACKNOWLEDGMENT The authors wish to thank Francis M. James, 111, MD, Professor of Anesthesia, Bowman Gray School of Medicine, and Mrs. Judy A. King for their assistance in the preparation of the manuscript.
REFERENCES 1. Dellepiane G, Badino P: L’anestesia paravertebrale in obstetrica e ginecologia. La Clinica Obstetrica. Riv Obstet GinecoI Pediatr 29:537-558, 1927 2. Cleland J G P : Paravertebral anesthesia in obstetrics. Surg Gynecol Obstet 57: 51-62, 1933 3. Shumacker HB, Manahan CP, Hellman LM: Sympathetic anesthesia in labor. Am J Obstet Gynecol 45:129, 1943 4. Reich AM: Paravertebral lumbar sympathetic block in labor. Am J Obstet Gynecol 61:1263-1276, 1951
5. Jarvis Shl: Paravertebral sympathetic nerve block: a method for the safe and painless conduct of labor. Am J Obstet Gynecol 47:335-342, 1944 Lumbar sympathetic block, in actice of Obstetric Analgesia and Anesthesia. Philadelphia, F.A. Davis Company, 1969, pp 520-526 7. Hunter CA: Uterine motility studies during labor. Am J Obstet Gynecol 65:681-666, 1963 8. Dripps RD, Eckenhoff J E , Vandam LD: Introduction to Anesthesia: The Principles of Safe Practice. Fourth edition. Philadelphia, W. B. Saunders, 1972, pp 5-7 9. Friedman EA: Primigravid labor: a graphicostatistical analysis. Obstet Gynec 6 :567-589, 1955 10. Moore DC: Paravertebral block of the second lumbar sympathetic ganglia, in Anesthetic Techniques for Obstetrical Anesthesia and Analgesia. Springfield, Illinois, Charles C Thomas, 1964, pp 325-128
11. Pritchard JA, MacDonald PC: Williams Obstetrics. Fifteenth edition. New York, AppletonCentury-Crofts, 1976, p p 358-359 12. Riekse J M : Terminal obstetrical anesthesia by means of lumbar sympathetic paravertebral block. Am J Obstet Gynecol 78:411-414, 1959 13. Burt RAP: The foetal and maternal pharmacology of some of the drugs used for the relief of pain in labor. Br J Anaesth 43:824-836, 1971 14. Moore DC, Bridenbaugh LD, Bridenbaugh PO, et al: Bupivacaine hydrochloride: a summary of investigational use in 3,274 cases. Anesth Analg 50: 856-872, 1971 15. Covino BG: Local anesthesia. Part 2. N Engl J Med 286: 1035.1042, 1972 16. Belfrrrge P, Berlin A, Baabe N, et al: Lumbar epidural analgesia with bupivacaine in labor. Drug concentrations in maternal and neonatal blood a t birth and delivery: the first day of life. Am J Obstet Gynecol 123:839-844, 1975 17. Thomas J, Long G, Moore G, et al: Plasma
490
Paravertebral Sympathetic Block for Labor
Anesth Analg
-,i ihf, 490, 1978
protein binding and placental transfer of bupivacaine. Clin Pharmacol Ther 19:426-434, 1976
with bupivacaine. Can Med Assoc J 110:1363-1365, 1974
18. Reynolds F, Taylor G: Plasma concentralions oi bupivacaine during continuous epidural analgesia in labor: the effects of adrenaline. Br J Anaesth 43:436-439, 1971
22. Littlewood DG, Scott DB, Wilson J. et al: Comparative anaesthetic properties of various local anaesthetic agents in extradural block for labour. Br J Anaesth 49:75-79, 1977
19. Browne RA, Catton DV: The use of hupivacame in labor, Can Anaesth Soc J 18:23-32, 1971
23. Gay GR, Evans J A : Total spinal anesthesia following lumbar paravertebral block: a potentially lethal complication. Anesth Analg 50.344-348, 1971
20. Freeman RK, Gutierrez NA, Ray ML, et al: Fetal cardiac response to paracervical block. Am J Obstet Gynecol 113:583-597, 1972 21. Baskett TF, Carson RM: Paracervical block
24. 1,earned LO. Cahool RF: Retroperitoneal hemorrhage as a complication of lumbar paravertebral injections: report of three cases. Anestbesiology 12:391-396, 1951
PREOPERATIVE ORAL ANTACID THERAPY Presence of a gastric pH of less than 2.5 and a volume greater than 25 ml identifies patients “at risk” of developing perioperative acid-aspiration pneumonitis. Preoperative oral antacid therapy has been used effectively to reduce the number of emergency obstetric patients “at risk.” Thirty-three nonobstetric adult patients requiring emergency surgery were selected to determine whether the protective effects of antacid therapy could also be derived i n this group. Fourteen patients who received 30 ml of combined magnesium and aluminum hydroxide antacid had 3 gastric pH (mean 2 SD) of 6.46 c 0.5 a n d gastric volume of 21.5 ? 3.6 ml, with none “at risk,” whereas 19 control patients had a mean pH of 3.71 5 0 43 a n d gastric volume of 71.5 c 16.5 m l with 42% “at risk.” These data suggest that preoperative antacid therapy should reduce the incidence of acid aspiration a n d subsequent morbidity and mortality i n patients requiring emergency surgery. (White F A , Clark RB, Thompson D S : Preoperative oral antacid therapy f o r
patients requiring emergency surgery. South M e d J 71:177-179, 1978)
P a r a v e r t e b r a l S y m p a t h e t i c Block for Labor
Anesth Analg 57-486-490,197X
Lumbar Sympathetic Block with Bupivacaine: Analgesia for Labor RAMON V. MEGUIAR, LT, MC, USNR" A. SCOTT WHEELER, LCDR, MC, USNRt Portsmouth, Virginia$
Forty primigravidas were given a bilateral paravertebral lumbar sympathetic block during stage I of labor using 10 cc of 0.5% bupivacitine and 1:200,000 epinephrine on each side. Good analgesia was obtained in 38 patients with maximal effect 7.5 -f. 3 minutes after hlockade. Maternal mean blood pressure and pulse were unchanged, fetal well-being was not compromised, and labor progressed rapidly. Twenty-eight patients delivered prior to resolution of the block, while in the remaining 12 patients pain returned before delivery with analgesia having lasted 283 t 103 minutes. In the former 28 patients, analgesia for expulsion was provided by pudendal, saddle block, or infiltrat ion analgesia, whereas continuous lumbar epidural or caudal analgesia was utilized when
I?
ARAVERTEBRAL lumbar svmpathetic block was first described for use in obstetrics in 1927.1 However, the mechanism of action was not greatly appreciated until 1933, when ('leland demonstrated that uterine and cervical visceral afferent sensory fibers join the sympathetic chain at L2-3.' Later authors reported the ease of administration of para\ ertebral sympathetic block, its reliability for producing analgesia during labor, and a low incidence of maternal side effects:' In addition, Hunter used tokodynamometry to demonstrate acceleration of the first stage of labor in 20 of 39 parturients given sympathetic blocks.' Significant detrimental fetal effects have not been reported."
Although sympathetic-block analgesia is
remission preceded s t a g e 11. I n comparison t o continuous lumbar epidural analgesia, t h e procedure is technically more difficult, generally more painful, and requires a second anesthetic for delivery. It is concluded that bilateral paravertebral lumbar sympathetic block with bupivacaine provides reliable analgesia of long duration with a low incidence of undesirable side effects. However, its primary usefulness is in cases where continuous lumbar epidural analgesia is refused or contraindicated. Key \Vords-ANESTHESIA, obstetric. ANESTHETIC TECHNICS, sympathetic block. SYMPATHETIC NERVOUS SYSTEM, paravertebral sympathetic block. ANESTHETICS, local, bupivacaine.
efficacious and relatively safe, its usefulness has been precluded by the short duration of action obtained with local anesthetic agents available in the past. We have re-examined the technic using the long-acting local anesthetic bupivacaine hydrochloride. Our results corroborate those cited before, except that in contradistinction to the earlier reports, the duration of analgesia with 0.5% bupivacaine was usually long enough. This report describes clinical features of this anesthetic technic in 40 parturients.
METHODS Forty primigravidas with a mean age of 21.7 years and a mean gestation of 40 weeks received a bilateral paravertebral lumbar
"Resident in Obstetrics and Gynecology ;Stafl Anesthesiologist. Present address: Assistant Professor of Anesthesia, Bowman Gray School of Medicine. Winston-Salem, North Carolina 27103
:Ikpartments of Anesthesiology and Obstetrics and Gynecology, Naval Regional Medical Center, Portsmouth, Virqinia 23508 This study has been sponsored and supported by the Bureau of Medicine and Surgery, Clinical Investigation Program No. CR 08-7-45. 'The opinions or assertions contained herein are those of the authors a n d are not to br construed a s official or reflecting viens of the Department of the Navy or of the Department of Defense. Addiess reprint requests to Dr. Wheeler. Section of Obstetric nnd Gynecologic Anesthesia, Forsyth Memorial Hospital. 3333 SIlas Creek Parkway, Winston-Salem, North Carolina 27103. Accepted for publication: May 4, 1978
Anesth Analg :a7:486-490. 1978
Meguiar and Wheeler
487
sympathetic block during the first stage of tem from zero to 3, with zero representing labor. They were all ASA I patients8 and no analgesia and 3 representing complete had unremarkable gestational histories ex- uterine analgesia. Scores of 2 or 3 were cept for a single patient at 28 weeks’ gesta- considered to represent satisfactory analgetion with premature rupture of membranes sia. The time from injection of the local and early chorioamnionitis. Thirty-three pa- anesthetic to complete cervical dilatation tients were in the active phase of labor, as was noted, as was the time to recurrence of described by Friedman,Qwhen cervical dila- abdominal or back discomfort. Anesthesia tation was 4 to 5 cm with uterine contrac- for delivery was provided by pudendal, lotions occurring every 3 minutes and lasting cal-infiltration, or saddle-block analgesia. more than 30 seconds. The remaining 7 pa- Continuous lumbar epidural or caudal tients were in the latent phase or had a dys- Flocks were administered when the symfunctional labor pattern. All patients under- pathetic block remitted prior to the second went continuous electronic monitoring of stage of labor. Neonatal Apgar scores were fetal heart rates and uterine contractions assigned at 1 and 5 minutes. Data were (Corometrics type I11 B) for at least 30 analyzed with Student’s t-test for paired minutes before sympathetic block. Fetal samples. Significance was assumed when heart rates were measured with scalp elec- p20%, reduction in madegree cephalad direction to identify the ternal blood pressure occurred in 2 patients, second lumbar transverse process. The nee- both of whom were in the supine position for dle was then withdrawn to the skin and vaginal examinations. The blood pressure redirected beneath and 4.5 cm beyond the returned to normal upon resumption of the transverse process with a 10-degree mesiad lateral position. The mean increase in skin angle. If the vertebral body was encoun- temperature of the lower extremity, 4.5 c tered, the needle was withdrawn and redi- 1.8 C, was achieved within 25 minutes. rected laterally 5 to 10 degrees. Ten milliAt the time of blockade, the mean cervilitres of 0.5% bupivacaine hydrochloride cal dilatation of the 33 patients in active with 1:200,000 epinephrine were injected on labor was 4.8 2 0.9 cm. There was no each side. change in the frequency of contractions, and Patients were then returned to the lateral the mean time from block to complete cerposition. The time from injection of the vical dilatation was 158 ? 92 minutes. In second side to maximum or complete uter- addition, mean fetal heart rates were not ine analgesia was noted. Frequency of con- changed, and a significant alteration in the tractions, maternal blood pressure and pulse, baseline variability of fetal heart rates was fetal heart rate, and skin temperature of not seen in any patient. However, 1 patient the lower extremity were recorded every 5 required cesarean section for sustained fetal minutes after blockade. Quality of maternal bradycardia occurring 150 minutes after the analgesia was ascertained by a scoring sys- block. This event was believed by the at-
488
Paravertebral Sympathetic Block for Labor
tending obstetrician to be secondary to umbilical-cord compression and unrelated to sympathetic block. This infant’s Apgar scores were 8 and 9. Apgar scores for the entire group were 7.9 ? 1.3 and 9.0 2 0.8 at 1 and 5 minutes, respectively.
DISCUSSION Pain in the first stage of labor is largely due to distention of the cervix and lower uterine segment. The sensory fibers from the uterus and cervix travel with sympathetic nerves passing through the posterior cervical plexus Frankenhauser’s plexus) and the superior hypogastric plexus to enter the sympathetic chain a t L2-3. They then ascend in the paravertebral sympathetic chain to enter the spinal cord via the white rami communicantes a t the 11th and 12th thoracic levels.’.’ 1 Therefore, a conduction blockade of the sympathetic chain at the 2nd lumbar vertebra prevents transmission of afferent sensory impulses from the cervix and uterus and will provide analgesia during labor.? r, The primary limitation to lumbar sympathetic block for labor has in the past been ihe short duration of analgesia. Shumacker et a1 obtained analgesia with 0.5% tetracaine, but the maximum duration was 4 hours.:: Various concentrations of procaine and piperocaine yield an average duration of 90 minutes;: lidocaine produces analgesia for 90 to 180 minutes.” We utilized bupivacaine because of its long duration of action, i t s reliable sensory blockade, and its appsrently low placental transfer.’:’-lT Our results show that 0.5% bupivacaine with 1:200,000 epinephrine ensures a more acceptable duration of analgesia, for the mean analgesia time of 283 minutes far exceeds that of all previously studied agents. The effect of epinephrine on duration of sympathetic blockade with bupivacaine is questionable. In epidural blockade, epinephrine decreases the rate of maternal absorption of bupivacaine but does not prolong its effect.’’ We used epinephrine with the intention of lessening t h e absorption and placental transfer of bupivacaine, not to prolong its duration of action. Notable features of bupivacaine sympathetic block were the rapid onset of action and high success rate of analgesia. Failure to obtain suitable analgesia in 2 of 40 patients compares favorably with a success rate of “over 90”/0,” as noted by Bonica.” Since this technic produces no motor block-
Anc,sth Antilg
,>7.4M~4WI,1978
ade, patients can move about freely and can “bear down” effectively in the second stage of labor. In addition, the progression of labor is rapid, a s evidenced by the mean block to complete cervical dilatation time of 158 minutes seen in the 33 patients in active labor. This finding compares favorably with the duration of labor noted after continuous lumbar epidural analgesia with 0.5% bupivacaine.’:’ Moreover, adverse effects of the technic on fetal heart rate were not observed. Thus, bupivacaine sympathetic block would apparently be more advantageous than paracervical block anesthesia, which has frequently been associated with fetal bradycardia.’” 2 1 Bonica quotes a 15 to 20% incidence of “mild hypotension” after lumbar sympathetic blocks.” In our study, the 5% incidence of maternal hypotension, which responded rapidly to position change, is most acceptable. Our incidence of hypotension may be lower because patients were hydrated before blockade and because they were placed in the lateral position after blockade. Although bilateral paravertebral sympathetic block can usually be completed within 10 minutes, it is generally more painful and technically more difficult than lumbar epidural analgesia. In addition, the use of sympathetic block for labor necessitates the ndministration of a second anesthetic for delivery. Continuous lumbar epidural analgesia not only provides good analgesia for vaginal delivery but also ensures successful anesthesia for cesarean section when necessary. Although the duration of analgesia with bupivacaine sympathetic block exceeds that observed after single-dose epidural blockade with bupivacaine,’!’ 1 2 the duration of analgesia was still insufficient in 30% of our patients. This finding substantiates our usual preference for continuous epidural anesthesia, especially for pitocininduced labors, which have unpredictable durations. A s a result, our use of continuous lumbar epidural anesthesia and sympathetic blocks for labor has approximated a ratio of 10 to 1. We use sympathetic blockade primarily when epidural analgesia is contraindicated or refused. For example, one patient in this study underwent lumbar fusion 4 years prior to admission, making epidural blockade impossible. Two patients were nurses who refused spinal and epidural anesthesia but consented to sympathetic blockade. While
Anesth Analg 57:486-490, 1978
not allowing the lumbar epidural block with 0.5% other mechanism stage I of labor.
Meguiar and Wheeler
flexibility of continuous anesthesia, sympathetic bupivacaine provides anto achieve analgesia for
Perineal analgesia for stage I1 is usually provided a€ter paravertebral sympathetic block with pudendal or saddle-block anesthesia. Pudendal blockade is preferred for spontaneous deliveries, whereas saddle block is utilized when forceps are indicated. We encourage our obstetricians to initiate puc’,endal anesthesia in the labor room when perineal discomfort becomes disconcerting.
It is noteworthy that total spinal anesthesia has been reported in 2 patients receiving lumbar sympathetic blockade.23 Meticulous attention to detail should prevent this complication. Inadvertent penetration into the retroperitoneal space with subsequent hemorrhage has been reported in 3 patients who received a series of paravertebral blocks for treatment of peripheral vascular disease.24 This complication was not mentioned in the literature we reviewed of lumbar sympathetic blocks for labor. Our incidence of intravascular needle placement is approximately 2%; hemorrhagic sequellae have not occurred. Furthermore, symptoms of maternal local anesthetic toxicity have not been encountered to date (in 325 cases). Due to possible increases in uterine contractility,7 caution should be exercised regarding the use of this anesthetic technic in parturients with tetanic labor patterns or with evidence oi uteroplacental insufficiency. In conclusion, bilateral paravertebral lumbar sympathetic blockade with 0.5% bupivacaine and 1:200,000 epinephrine is an effective anesthetic technic for labor, yielding a high incidence of good uterine analgesia. The duration of sensory blockade with bupivacaine greatly exceeds the duration of blockade seen with other local anesthetic agents. In our study, uterine analgesia persisted throughout delivery in 70% of our primigravid patients. Labor progresses well, and the block is not commonly associated with maternal or fetal complications. However, hypotension can occur, and blood presLure must be monitored. Since continuous lumbar epidural analgesia is less painful, technically less difficult, and can be extended to provide analgesia for vaginal or abdominal delivery, bupivacaine sympathetic blockade is primarily utilized when continuous lumbar epidural analgesia is contraindicated.
489
ACKNOWLEDGMENT The authors wish to thank Francis M. James, 111, MD, Professor of Anesthesia, Bowman Gray School of Medicine, and Mrs. Judy A. King for their assistance in the preparation of the manuscript.
REFERENCES 1. Dellepiane G, Badino P: L’anestesia paravertebrale in obstetrica e ginecologia. La Clinica Obstetrica. Riv Obstet GinecoI Pediatr 29:537-558, 1927 2. Cleland J G P : Paravertebral anesthesia in obstetrics. Surg Gynecol Obstet 57: 51-62, 1933 3. Shumacker HB, Manahan CP, Hellman LM: Sympathetic anesthesia in labor. Am J Obstet Gynecol 45:129, 1943 4. Reich AM: Paravertebral lumbar sympathetic block in labor. Am J Obstet Gynecol 61:1263-1276, 1951
5. Jarvis Shl: Paravertebral sympathetic nerve block: a method for the safe and painless conduct of labor. Am J Obstet Gynecol 47:335-342, 1944 Lumbar sympathetic block, in actice of Obstetric Analgesia and Anesthesia. Philadelphia, F.A. Davis Company, 1969, pp 520-526 7. Hunter CA: Uterine motility studies during labor. Am J Obstet Gynecol 65:681-666, 1963 8. Dripps RD, Eckenhoff J E , Vandam LD: Introduction to Anesthesia: The Principles of Safe Practice. Fourth edition. Philadelphia, W. B. Saunders, 1972, pp 5-7 9. Friedman EA: Primigravid labor: a graphicostatistical analysis. Obstet Gynec 6 :567-589, 1955 10. Moore DC: Paravertebral block of the second lumbar sympathetic ganglia, in Anesthetic Techniques for Obstetrical Anesthesia and Analgesia. Springfield, Illinois, Charles C Thomas, 1964, pp 325-128
11. Pritchard JA, MacDonald PC: Williams Obstetrics. Fifteenth edition. New York, AppletonCentury-Crofts, 1976, p p 358-359 12. Riekse J M : Terminal obstetrical anesthesia by means of lumbar sympathetic paravertebral block. Am J Obstet Gynecol 78:411-414, 1959 13. Burt RAP: The foetal and maternal pharmacology of some of the drugs used for the relief of pain in labor. Br J Anaesth 43:824-836, 1971 14. Moore DC, Bridenbaugh LD, Bridenbaugh PO, et al: Bupivacaine hydrochloride: a summary of investigational use in 3,274 cases. Anesth Analg 50: 856-872, 1971 15. Covino BG: Local anesthesia. Part 2. N Engl J Med 286: 1035.1042, 1972 16. Belfrrrge P, Berlin A, Baabe N, et al: Lumbar epidural analgesia with bupivacaine in labor. Drug concentrations in maternal and neonatal blood a t birth and delivery: the first day of life. Am J Obstet Gynecol 123:839-844, 1975 17. Thomas J, Long G, Moore G, et al: Plasma
490
Paravertebral Sympathetic Block for Labor
Anesth Analg
-,i ihf, 490, 1978
protein binding and placental transfer of bupivacaine. Clin Pharmacol Ther 19:426-434, 1976
with bupivacaine. Can Med Assoc J 110:1363-1365, 1974
18. Reynolds F, Taylor G: Plasma concentralions oi bupivacaine during continuous epidural analgesia in labor: the effects of adrenaline. Br J Anaesth 43:436-439, 1971
22. Littlewood DG, Scott DB, Wilson J. et al: Comparative anaesthetic properties of various local anaesthetic agents in extradural block for labour. Br J Anaesth 49:75-79, 1977
19. Browne RA, Catton DV: The use of hupivacame in labor, Can Anaesth Soc J 18:23-32, 1971
23. Gay GR, Evans J A : Total spinal anesthesia following lumbar paravertebral block: a potentially lethal complication. Anesth Analg 50.344-348, 1971
20. Freeman RK, Gutierrez NA, Ray ML, et al: Fetal cardiac response to paracervical block. Am J Obstet Gynecol 113:583-597, 1972 21. Baskett TF, Carson RM: Paracervical block
24. 1,earned LO. Cahool RF: Retroperitoneal hemorrhage as a complication of lumbar paravertebral injections: report of three cases. Anestbesiology 12:391-396, 1951
PREOPERATIVE ORAL ANTACID THERAPY Presence of a gastric pH of less than 2.5 and a volume greater than 25 ml identifies patients “at risk” of developing perioperative acid-aspiration pneumonitis. Preoperative oral antacid therapy has been used effectively to reduce the number of emergency obstetric patients “at risk.” Thirty-three nonobstetric adult patients requiring emergency surgery were selected to determine whether the protective effects of antacid therapy could also be derived i n this group. Fourteen patients who received 30 ml of combined magnesium and aluminum hydroxide antacid had 3 gastric pH (mean 2 SD) of 6.46 c 0.5 a n d gastric volume of 21.5 ? 3.6 ml, with none “at risk,” whereas 19 control patients had a mean pH of 3.71 5 0 43 a n d gastric volume of 71.5 c 16.5 m l with 42% “at risk.” These data suggest that preoperative antacid therapy should reduce the incidence of acid aspiration a n d subsequent morbidity and mortality i n patients requiring emergency surgery. (White F A , Clark RB, Thompson D S : Preoperative oral antacid therapy f o r
patients requiring emergency surgery. South M e d J 71:177-179, 1978)
