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Canadian Journal of Anesthesia 48:179-184 (2001)
© Canadian Anesthesiologists' Society, 2001
Obstetrical and Pediatric Anesthesia

Bilateral paravertebral block: a satisfactory alternative for labour analgesia

Vinod Nair, MD and Richard Henry, MBCHB FRCPC

From the Department of Anesthesiology, Queen's University, Kingston General Hospital, 76 Stuart Street, Kingston, Ontario, K7L 2V7 Canada.

Address correspondence to:Dr. Richard Henry, Phone: 613-548-7827; Fax: 613-548-1375; E-mail: henryr{at}kgh.kari.net


   Abstract
TOP
 Abstract
Paravertebral block technique
 Discussion
 Conclusion
 References
 
Purpose: To describe a new technique of paravertebral block for labour analgesia and to report the successful use of bilateral paravertebral block in four parturients with contraindications to conventional labour epidural analgesia.

Clinical Features: Four parturients with contraindications to lumbar epidural analgesia, who were seen either in consultation prenatally or after requesting analgesia when in labour, consented to paravertebral blocks for the management of first stage of labour pain. Bilateral paravertebral blocks were performed at T10-L1 level, initially blocking all four levels with 4 ml bupivacaine 0.5% with epinephrine 1:200000 and then reducing the number of levels blocked to two and finally one. With the entry point 2 cm lateral to the inferior edge of the T11 spinous process, a 22G spinal needle was advanced perpendicular to all planes until contact was made with the transverse /superior articular process of T12, at a depth of 3-5 cm. The needle was then walked superiorly (T11) and inferiorly (T12 nerve root) off the transverse/articular process and advanced 1.5 cm into the paravertebral space.

All four patients had relief of pain such that they were "comfortable" and able to cope with labour although they continued to experience deep pelvic and rectal pain. The patients tolerated the initiation of the blocks well, remained hemodynamically stable, and did not suffer any adverse effects.

Conclusion: Bilateral paravertebral block provides adequate analgesia for the first stage of labour and could be an alternative analgesic technique for some parturients with contraindications to conventional labour epidurals.

LUMBAR epidural analgesia has established itself as the gold standard for labour analgesia.1,2 In addition to the obvious analgesic benefits, the lumbar sympathectomy provided by an epidural may also speed up the first stage of labour.3 However, clinical contraindications (coagulopathy, anatomical abnormality and infection) and personnel/institutional limitations preclude some parturients from receiving an epidural.4,5 Alternatives to epidurals such as opioids and nitrous oxide provide inferior analgesia and are associated with a higher incidence of neonatal depression and adverse maternal psychological effects.2

Paravertebral block has been used to provide analgesia for a variety of pain problems.6,7 However, the only reports of their use for labour analgesia were in 1927 and 1933.8,9 We report the successful use of a modified technique for bilateral paravertebral blocks for labour analgesia in four patients who had contraindications to lumbar epidurals.


   Paravertebral block technique
TOP
 Abstract
 Paravertebral block technique
Discussion
 Conclusion
 References
 
The anatomical differences between the thoracic and lumbar vertebrae occur at the level of the T12 vertebral body. The T12 transverse process is smaller and more medial than its higher counterparts and is fused with the T12 superior articular process. Structurally, it resembles the superior articular processes of the lumbar vertebral bodies. (Figure 1Go) We used these boney prominences as our landmarks for paravertebral block at the T10-L1 level.



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  		FIGURE 1

 
Our goal was to deposit local anesthetic into the lateral aspect of the intervertebral foramen, the paravertebral space, to anesthetize the ventral nerve root and the sympathetic chain. (Figure 2Go) Local anesthetic deposited at this site spreads cephalad and caudad, covering 2-10 segments depending on the volume used.6 Although we initially injected all four of the T10 to L1 nerve roots bilaterally, we subsequently found that either a bilateral single level block of T11, or both T11 and T12 roots, provided an equally effective block for the first stage labour.



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  		FIGURE 2

 
Local anesthetic was infiltrated subcutaneously at the entry point 2 cm lateral to the inferior edge of the T11 spinous process with a 30G needle. A 22G, 9 cm (31/2 inch) spinal needle was then inserted and advanced perpendicular to all planes until contact was made with the transverse /superior articular process of T12, usually at a depth of 3-5 cm. (Figures 1,3GoGo) The needle was then walked superiorly (T11 nerve root) and inferiorly (T12 nerve root) off the transverse/articular process and advanced 1.5 cm. Care was taken not to direct the needle medially to avoid dural puncture. If bone was still contacted, the needle was directed slightly laterally. Aspiration for blood and cerebrospinal fluid was done prior to injecting local anesthetic in small aliquots. For continuous catheter techniques, a 17G Tuohy needle was used. The catheter was advanced just beyond the tip of the needle and the needle withdrawn. This procedure was repeated on the opposite side and a sterile dressing placed over the catheters.



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  		FIGURE 3

 
Case report #1
A 31-yr-old G3P0A2 was assessed by the Hematology Department during her pregnancy because of a history of bruising and prolonged bleeding. The coagulation profile, including tests for von Willebrand's disease and hemophilia, was normal, except for a prolonged bleeding time. No etiology for this was found. The hematologist recommended having packed red blood cells and platelets available in the event of a Cesarean section or post-partum hemorrhage. Options for labour analgesia were reviewed with the patient by Anesthesiology, including the risks of epidural hematoma and the possible use of paravertebral block.

She was admitted at 41 wk gestation for induction following an uneventful antenatal course. As labour progressed, she received three doses of 15 mg morphine im over eight hours. The membranes were artificially ruptured and oxytocin iv was required to augment labour, but was limited because of increasingly painful contractions. The patient requested paravertebral block.

Using the technique described, 32 ml bupivacaine 0.5% with epinephrine 1:200000 was injected at the level of T10 and T12 spinous processes bilaterally, infiltrating 4 ml above and below the T11 and L1 transverse/superior articular processes (i.e. T10, 11, 12 and L1 nerve root infiltration). The patient's pain was dramatically relieved within 10 min from 10/10 to 3/10. Blood pressure and heart rate remained stable.

Analgesia lasted nearly four hours, at which time supplemental analgesia was requested and was provided again with morphine. Six hours after the initial paravertebral block, the procedure was repeated using a 17G Tuohy needle for placement of bilateral catheters at T11. Twelve milliliters of the same solution were used on each side with excellent results.

After 12 hr of labour, the cervix was only dilated to 5 cm. Cesarean section was performed under general anesthesia for failure to progress and the paravertebral catheters were removed. A healthy male neonate was delivered with Apgar scores of 3 and 6. There were no complications noted from the paravertebral blocks.

Case report #2
A 27-yr-old primigravida presented in spontaneous labour at term. The patient had undergone neuroblastoma resection at the age of six months followed by numerous surgical procedures on her lower extremities and back which left her with leg weakness, arachnoiditis, and a neurogenic bladder. Analgesic options for labour, including paravertebral blocks, were discussed with the patient in consultation with Anesthesiology before the onset of labour.

Morphine, 15 mg im, and nitrous oxide 50% in oxygen provided adequate analgesia for the first stage of labour, and she achieved complete dilatation of her cervix with oxytocin augmentation. Then, she started to complain of severe back pain such that she was unable to push with her contractions and the oxytocin had to be discontinued. Supplemental analgesia was requested and paravertebral blocks were performed.

Paravertebral blocks were placed as in Case 1 using 5 ml bupivacaine 0.25% with 1:200000 epinephrine at each nerve root for a total of 40 ml. Hemodynamic stability was maintained and her pain score was reduced to 1/10. She fell asleep within 15 min and the oxytocin infusion was restarted.

Two hours later, the obstetrician performed a pudendal nerve block and delivered a healthy baby, with Apgar scores of 5 and 9, using mid-forceps. The third stage was complicated by an avulsed umbilical cord. Manual extraction of the placenta was completed hours later with the addition of another pudendal nerve block. No complications were encountered and the patient remained hemodynamically stable.

Case report #3
A 30-yr-old G3P1 at 40 wk gestation presented in spontaneous labour after an uncomplicated antenatal course. Her past medical history was significant for spina bifida occulta. Anesthesiology declined an epidural and provided PCA fentanyl ( 25 µg bolus, lockout five minutes, no basal infusion). After five hours, the patient began to complain of severe labour pain, rating it at 10/10 and was unable to cope with oxytocin augmentation. After consultation with the author, paravertebral blocks were offered, and the patient consented.

Bilateral single-shot paravertebral blocks were performed above (T11 nerve root) and below (T12 nerve root) the T12 transverse/articular processes, with 7.5 ml bupivacaine 0.5% with epinephrine 1:200000 at each root (total 30 ml). The pain score decreased to 5/10 within 10 min, with residual suprapubic pain. The PCA fentanyl was left with the patient but was used minimally.

Three hours later, the pain recurred, mainly in the perineal and suprapubic areas. The large fetus was noted to be in the OP position. The blocks were repeated with 20 ml of the same solution deposited above and below T11 bilaterally. Again, her pain settled within 10 min. However, despite oxytocin augmentation, the fetal head did not engage and a Cesarean section was performed under general anesthesia for failure to progress. A healthy 3730 g, female neonate with Apgar scores of 4 and 9 was delivered.

Case report #4
This 33-yr-old G2P1 presented at term after an uneventful antenatal course with right upper quadrant pain. She was subsequently diagnosed with HELLP syndrome. As labour progressed she requested analgesia. Given the degree of thrombocytopenia (platelet count 41 x 109•L–1), Anesthesiology declined an epidural. Other means of analgesia were discussed and the patient consented to bilateral paravertebral block. In anticipation of a prolonged labour, bilateral paravertebral catheters were inserted at T11 as described above. Fifteen milliliters of bupivacaine 0.5% with epinephrine 1:200000 were injected into each catheter. She remained hemodynamically stable, and felt comfortable within 15 min. A female neonate was delivered with Apgar scores of 9 and 9 about 90 min after initiation of the block. There were no complications.

Paravertebral blocks provided three to four hours of analgesia for the first stage of labour, and controlled the back pain associated with contractions well. All four patients experienced a rapid diminution of their labour pain from an unbearable 10/10 to a tolerable 1-5/10. Their back pain, in particular, was completely relieved and they were able to cope with the residual pelvic pressure. Perineal pressure from the fetal head and second stage labour pain were not blocked by this technique, requiring supplemental opioids and/or pudendal nerve blocks in some cases. All of the patients experienced abdominal sensory deficit, no significant hemodynamic changes were observed and none of them required urinary bladder catheterization. Our patients were satisfied with the performance of the block and would undergo paravertebral blocks again if an epidural remained contraindicated. On follow-up the first day post-partum, none of them had any residual neurological symptoms.


   Discussion
TOP
 Abstract
 Paravertebral block technique
 Discussion
Conclusion
 References
 
We initiated paravertebral blocks for labour with four blocks bilaterally and evolved to using single level bilateral injections with acceptable results. Paravertebral catheters with continuous infusion of local anesthetic could be used if labour is anticipated to continue for longer than three hours. We considered using bupivacaine 0.1 - 0.25% plain at 5 ml•hr-1 bilaterally as the initial infusion rate, using separate infusion pumps. Furthermore, the infusion could be continued for post-Cesarean section analgesia for the first 24 hr.

The first reported use of paravertebral block by Hugo Sellheim in 1905 claimed to avoid the potential cardiovascular collapse associated with spinal anesthesia.10 Dellepiane and Badino in 19278 and Cleland in 19339 described the use of paravertebral blocks in labour for the management of first stage labour pain. Dellepiane developed an intricate technique for blocking the hypogastric plexus and although they were successful in abolishing the pain of uterine contractions, the technique was too difficult and considered impractical for routine use. Cleland, using animal experiments as the basis for his arguments, hypothesized that the uterine afferent roots in the human are in the eleventh and twelfth thoracic nerve roots. He then reported on five cases of paravertebral nerve blocks using 5 ml novocaine 1% at T11 and T12 bilaterally for first stage labour pain, using a supplemental caudal block for the perineal pain of second stage labour.

There are no other reports of regional anesthesia in labour until lumbar sympathetic blocks (LSB) for labour analgesia were explored in the 1940s. They were found to provide good analgesia for the first stage of labour, minimal motor weakness, and "rapid dilatation of the cervix", reducing the duration of the first stage of labour.11–13 Two subsequent trials published in 1978 and 1999, confirmed the efficacy of LSB for labour but found them to be technically more difficult and more painful to perform with a higher risk for serious complications than lumbar epidurals.14,15

Anatomically, the thoracic paravertebral space is defined posteriorly by the superior costotransverse ligament, anteriorly by the parietal pleura, medially by the postero-lateral aspect of the vertebral body, the intervertebral disc and the intervertebral foramen, and laterally by the posterior intercostal membrane.6 (Figure 2Go) In the lumbar region, the psoas muscle provides the anterior border and it has been considered an impediment to spread of local anesthetic to the lumbar region.16 However, spread does occur via the medial and lateral arcuate ligaments of the diaphragm, by the epidural space, and by communications anterior to the vertebral bodies.17,18 Structures in the paravertebral space include the spinal nerve, dorsal ramus, rami communicantes, and anteriorly, the sympathetic chain.

The anatomical landmarks used to identify the paravertebral space include the transverse process, the vertebral body, and the lamina of the vertebrae.6,7,19 The classic approach utilizes the transverse process as the bony landmark, approaching from 3-4 cm lateral to the midline, with the needle advanced perpendicular to all skin planes.6 After contact with the transverse process, the needle is redirected above or below with a medial direction, until contact is made with the vertebral body. Shaw (1952) and Bonica (1959), aiming to reduce the incidence of pneumothorax and dural puncture, described the paralaminar technique.19,20 Needle entry is 1-1.5 cm lateral to midline and directed perpendicular to all skin planes until contact is made with the lamina, from which the needle is then walked laterally and advanced 1 cm further. Tenicela and Pollan (1990) described the ‘paravertebral-peridural' technique.21 Starting 3 cm lateral to the midline, the needle is advanced at a 45 angle medially towards the lamina. Upon contact, the needle is walked off the lateral edge of the lamina by redirecting the needle closer to the perpendicular, restricting advancement of the needle to 1.0-1.5 cm beyond the lamina.

We have simplified the paravertebral technique further. The 12th thoracic transverse processes are structurally similar to the superior articular processes of the lumbar vertebrae, while the lumbar transverse processes are deeper to skin, narrower and longer than their thoracic counterparts. The lumbar superior articular processes are only 1.5-2 cm lateral to midline and approximately 0.5-1.0 cm closer to the skin surface than their corresponding transverse processes. (Figures 1,3GoGo)

We aim to make contact with the transverse process of T11 and the superior articular process of T12 and L1, and then redirect the needle cephalad or caudad from this bony landmark while maintaining the needle in the same sagittal plane. Advancing 1.5 cm beyond the bony landmark places the needle tip well into the medial aspect of the paravertebral space. This technique remains the same, even with the transition from thoracic to lumbar vertebral anatomy. (Figure 1Go)

The failure rate for paravertebral blocks performed in surgical patients was found to be 10%, with the following incidence of complications: hypotension (4.6%), vascular puncture (3.8%), pleural puncture (1.1%), and pneumothorax (0.5%).22 The incidence of urinary retention and hypotension was lower with paravertebral blocks compared to epidurals in thoracotomy patients.23 There has been one report of a total spinal as a consequence of a paravertebral block using the transverse process as the landmark.24 Should vessel puncture occur, the consequences of a hematoma in the paravertebral space are unknown. Based on the work of Saito et al., although a paravertebral hematoma may possibly track back into the epidural space, blood is more likely to spread away from the vertebral foramina.17


   Conclusion
TOP
 Abstract
 Paravertebral block technique
 Discussion
 Conclusion
References
 
Lumbar epidural analgesia has become the standard for labour analgesia. In situations where an epidural is contraindicated, current alternatives can fall short in providing adequate pain relief. LSBs have been used as an alternative with success, but are technically demanding and therefore not suitable for general use. Our case series exemplifies four such scenarios where epidurals were absolutely or relatively contraindicated. Paravertebral blocks were used with good results for the management of the first stage of labour, and offer a useful alternative for some parturients with contraindications to epidurals. Given the ease of performance, degree of analgesia, and stable hemodynamics this procedure warrants further investigation as an alternative or supplement to parenteral opioids and/or nitrous oxide.

Further scrutiny is required in order to confirm the role and safety of paravertebral blocks when epidurals are contraindicated. The optimum number of levels injected, and the optimum concentration and volume of local anesthetic required needs to be determined.


   Acknowledgments
 
The authors would like to acknowledge Drs. Hugh Brown and Ron Seegobin who taught us the paravertebral technique and encouraged this work. We also thank Dr. Alison Froese for her insightful editorial advice.

Accepted for publication October 30, 2000.


   References
TOP
 Abstract
 Paravertebral block technique
 Discussion
 Conclusion
 References
 
1 Chestnut DH, McGrath JM, Vincent RD Jr, et al. Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are in spontaneous labor? Anesthesiology 1994; 80: 1201–8.[Medline]

2 Halpern SH, Leighton BL, Ohlsson A, Barrett JFR, Rice A. Effect of epidural vs parenteral opioid analgesia on the progress of labour: A meta-analysis. JAMA 1998; 280: 2105–10.[Abstract/Free Full Text]

3 Leighton BL, Halpern SH, Wilson DB. Lumbar sympathetic blocks speed early and second stage induced labor in nulliparous women. Anesthesiology 1999; 90: 1039–46.[Medline]

4 Brown DL. Spinal, epidural and caudal anesthesia. In: Miller RD (Ed.). Anesthesia 5th ed. New York: Churchill Livingstone Inc., 2000: 1492.

5 Macario A, Scibetta WC, Navarro J, Riley E. Analgesia for labor pain. A cost model. Anesthesiology 2000; 92: 841–50.[Medline]

6 Richardson J, Lönnqvist PA. Thoracic paravertebral block. Br J Anaesth 1998; 81: 230–8.[Free Full Text]

7 Eason MJ, Wyatt R. Paravertebral thoracic block - a reappraisal. Anaesthesia 1979; 34: 638–42.[Medline]

8 Dellepiane G, Badino P. L'anestesia paravertebrale in ostetricia e ginecologia. La Clinica Ostetrica 1927; 29: 537–58.

9 Clelend JGP. Paravertebral anaesthesia in obstetrics. Experimental and clinical basis. Surg Gynecol Obstet 1933; 57: 51–62.

10 Mandl F. Paravertebral Block. New York: Grune and Stratton, 1946.

11 Shumacker HB, Manahan CP, Hellman LM. Sympathetic anesthesia in labor. Am J Obstet Gynecol 1943; 45: 129.

12 Jarvis SM. Paravertebral sympathetic nerve block, a method for the safe and painless conduct of labor. Am J Obstet Gynecol 1944; 47: 335–42.

13 Reich AM. Paravertebral lumbar sympathetic block in labor. A report on 500 deliveries by a fractional procedure producing continuous conduction anesthesia. Am J Obstet Gynecol 1951; 61: 1263–76.

14 Meguiar RV, Wheeler AS. Lumbar sympathetic block with bupivacaine: analgesia for labor. Anesth Analg 1978; 57: 486–92.[Abstract/Free Full Text]

15 Suelto MD, Shaw DB. Labor analgesia with paravertebral lumbar sympathetic block. Reg Anesth Pain Med 1999; 24: 179–81.[Medline]

16 Lönnqvist PA, Hildingsson U. The caudal boundary of the paravertebral space. A study in human cadavers. Anaesthesia 1992; 47: 1051–2.[Medline]

17 Saito T, Den S, Tanuma K, Tanuma Y, Carney E, Carlsson C. Anatomical bases for paravertebral anesthetic block: fluid communication between the thoracic and lumbar paravertebral regions. Surg Radiol Anat 1999; 21: 359–63.[Medline]

18 Karmakar MK, Kwok WH, Kew J. Thoracic paravertebral block: radiological evidence of contralateral spread anterior to the vertebral bodies. Br J Anaesth 2000; 84: 263–5.[Abstract/Free Full Text]

19 Bonica JJ, Butler SH. Local anaesthesia and regional blocks. In: Wall PD, Melzack R (Eds.) Textbook of Pain, 3rd ed. New York: Churchill Livingstone Inc., 1994: 1013.

20 Shaw WM, Hollis NY. Medial approach for paravertebral somatic nerve block. JAMA 1952; 148: 742–4.

21 Tenicela R, Pollan SB. Paravertebral-peridural block technique: a unilateral thoracic block. Clin J Pain 1990; 6: 227–34.[Medline]

22 Lönnqvist PA, MacKenzie J, Soni AK, Conacher ID. Paravertebral block. Failure rate and complications. Anaesthesia 1995; 50: 813–5.[Medline]

23 Matthews PJ, Govenden V. Comparison of continuous paravertebral and extradural infusions of bupivicaine for pain relief after thoracotomy. Br J Anaesth 1989; 62: 204–5.[Abstract/Free Full Text]

24 Gay GR, Evans JA. Total spinal anesthesia following lumbar paravertebral block: a potentially lethal complication. Anesth Analg 1971; 50: 344–8.[Free Full Text]




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