Bilateral thoracic paravertebral block: potential and practice

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1 British Journal of Anaesthesia 106 (2): (2011) doi: /bja/aeq378 REVIEW ARTICLE Bilateral thoracic paravertebral block: potential and practice J. Richardson 1 *,P.A.Lönnqvist 2 and Z. Naja 3 1 Department of Pain and Anaesthetics, Bradford Royal Infirmary, Bradford BD9 6RJ, UK 2 Karolinska Institute, Stockholm, Sweden 3 Makassed General Hospital, Beirut, Lebanon * Corresponding author. docjohnnyr@hotmail.com Editor s key points Paravertebral blocks can provide good intra- and postoperative analgesia. Large doses may be required, but toxicity has not been reported. The incidence of complications and side-effect seems low. The limited evidence available is supportive of their use. Summary. Paravertebral nerve blocks (PVBs) can provide excellent intraoperative anaesthetic and postoperative analgesic conditions with less adverse effects and fewer contraindications than central neural blocks. Most published data are related to unilateral PVB, but its potential as a bilateral technique has been demonstrated. Bilateral PVB has been used successfully in the thoracic, abdominal, and pelvic regions, sometimes obviating the need for general anaesthesia. We have reviewed the use of bilateral PVB in association with surgery and chronic pain therapy. This covers 12 published studies with a total of 538 patients, and with varied methods and outcome measures. Despite the need for relatively large doses of local anaesthetics, there are no reports of systemic toxicity. The incidence of complications such as pneumothorax and hypotension is low. More studies on the use of bilateral PVB are required. Keywords: anaesthetic techniques; regional, paravertebral; pain; postoperative Thoracic paravertebral nerve blocks (PVBs) can provide highquality analgesia which can be used to great advantage for patients undergoing many types of surgery, and also for those suffering from trauma pain and chronic pain. Although most clinical reports and research relate to unilateral PVB, a diversity of publications challenges the assumption that it cannot be applied to midline surgery. Bilateral PVB has been successfully used in the thoracic, abdominal, and pelvic regions. This review gathers together these publications and suggests this block as an alternative to central neural blocks. This is a descriptive, narrative review as research studies are relatively few and their methods vary greatly. Paravertebral analgesia is produced by placing local anaesthetic (LA) alongside the vertebral column, close to the emergence of the spinal nerve. PVB was first described by Sellheim of Leipzig in 1905 as an alternative to central neural blocks for obstetrics, particularly Caesarean section. 12 Soon after, it was applied to upper abdominal surgery. 3 Bilateral PVB for surgical anaesthesia was probably in widespread use in the first half of the twentieth century, 2 but judging by publication rates, since then has almost died out. The paravertebral space This is a potential space, which is turned into a temporary cavity by fluid (e.g. LA) (Figs 1 4) forming a wedge-shaped space (Table 1). 4 Of the structures passing through the paravertebral space (PVS) (Table 2), the most important are the intercostal and sympathetic nerves. 4 Spread of LA alongside the spine to adjacent PVS, anterior to the transverse processes, produces multilevel block. 4 In addition to superior and inferior movement of injectate within the paravertebral gutter across the heads and necks of ribs, there are other potential sites of spread (Figs 1 4). Medial spread through the intervertebral foramen into the epidural space has been observed fluoroscopically. Surprisingly, its incidence in chronic pain patients was reported in one study to be 70%, with 31% of patients demonstrating exclusively epidural spread, 5 although almost all other studies and reviews have stated that this is a rare, or very rare event. 7 8 With multilevel bilateral thoracic PVB using a nerve stimulator-guided technique in 61 patients undergoing a total of 368 injections, we were unable to observe any clinical or radiological epidural or contralateral spread. 9 Lateral spread into the intercostal space can occur. Anterior spread will not occur unless the pleura is breached. Thoracic PVB comes about through deposition of LA outside ( posterior) to the parietal pleura: in the same tissue plane as the neurological structures. Intrapleural analgesia involves LA deposition between the two layers of pleurae: deep to the parietal pleura and superficial to the visceral pleura. Therefore, data relating to intrapleural analgesia are not relevant to PVB. Particularly after a thoracotomy, the spread of an intrapleural injection follows mainly a gravitational path. In a sitting patient, it will pool on the diaphragm, & The Author [2011]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please journals.permissions@oup.com

2 Bilateral paravertebral blocks Fig 1 Bilateral PVB with X-ray contrast medium added to LA. Typical and optimal contrast medium distribution is shown. Fig 3 X-ray contrast medium injected alongside the vertebral column in a patient being treated for chronic pain has entered an intervertebral foramen and is seen in the contralateral PVS. Such extensive bilateral spread from a single unilateral injection is almost unique. Fig 2 Bilateral PVB with X-ray contrast medium added to LA. Typical and optimal contrast medium distribution is shown with the addition of some spread around the intercostal spaces on the left. and may actively contribute to impaired pulmonary function (LA is actively taken up by the diaphragm) Dependent chest drain losses of LA, which can be 30 40% with intrapleural blocks, 14 are much less with PVB. 10 This generally results in poor-quality analgesia and we, and others, 16 are of the opinion that intrapleural analgesia for postthoracotomy pain relief should be regarded as obsolete. Mechanism of action Anaesthesia occurs because of direct penetration of LA into the neurological structures contained within the PVS (Table 2) The spinal nerve, lacking both an epineurium and part of the perineurium and with only a thin membranous root sheath is easily penetrated by LA and hence easily and efficiently blocked Although mass Fig 4 A lateral view of the same patient as Figure 3. X-ray contrast medium is seen surrounding a number of spinal/intercostal nerves in their intervertebral foramen. movement of drug across further tissue planes is unnecessary for analgesia, movement of LA away from a correctly placed PVB, as described above, can contribute to analgesia. 165

3 Table 1 Boundaries of PVS Direction Posterior Anterior Medial Superior Inferior Lateral Notes Superior costotransverse ligament. Further lateral the posterior intercostal membrane Parietal pleura Postero-lateral aspect of the vertebra, intervertebral disc, intervertebral foramen Heads and necks of the ribs Limited by the crurae of the diaphragm, although not all authors agree 59 No limit, contiguous with the intercostal space Table 2 The neural structures in the PVS Nerve Anterior ramus of the intercostal nerve Posterior ramus of the intercostal nerve Sympathetic chain Rami communicantes Sinu-vertebral nerve Notes The spinal nerve only exists within the intervertebral foramen On the lateral/anterolateral vertebral body Gray and white The Nerve of Luska supplies a part of the intervertebral disc Quality of analgesia and theory of causation A high quality of block which can provide anaesthesia sufficient to carry out major surgery has been demonstrated in various anatomical sites Low postoperative pain scores and an opioid-sparing effect have also been shown. Inhibition of somatosensory-evoked potentials (SSEPs) by PVB at the injected level and multiple adjacent levels indicates that cerebral cortical responses can be effectively abolished with clinically acceptable doses of bupivacaine. 22 We are unaware of any studies which have shown equivalent inhibition of thoracic SSEPs with other regional anaesthetic techniques, including epidural and spinal anaesthesia, suggesting that block quality of PVB is unique. 22 With central neural blocks, the sympathetic chain is unaffected which is not the case with PVB. In one study, bupivacaine 0.5% (15 ml) produced a mean somatic block of five dermatomes accompanied by a mean sympathetic block of eight dermatomes, as evidenced by thermographic ipsilateral skin warming. 23 In another study, lidocaine 1% (22 ml) at T11 in 16 volunteers resulted in a unilateral somatic block of 12 (range 8 13) dermatomes and a sympathetic block, as indicated by ipsilateral skin warming, of at least six dermatomes. 24 We suggest that blockade of the sympathetic chain is important because afferent inputs which travel rostrally within this nerve pathway will be immune to the central neural block (no matter how profound). This quality of afferent block probably helps to explain the effect on acute and chronic pain by PVB PVB appears to inhibit the stress response to major surgery above the umbilicus, in contrast to the belief that for thoracic or upper abdominal surgery, the stress response is unpreventable by nerve blocks alone. 33 Good preservation of postoperative pulmonary function has been demonstrated, particularly in thoracotomy, which is a significant benefit over epidural analgesia. Bilateral PVB The use of bilateral PVB has been described in 541 patients in various study formats (Table 3). Good results have been demonstrated with a low level of reported side-effects and no serious complications. A variety of techniques, including loss of resistance, nerve stimulators, and ultrasound, have been used (Table 4). 467 Drugs and doses Richardson et al. Bupivacaine and lidocaine, both with and without epinephrine, are the most frequently studied, although most relate to unilateral PVB either with a single bolus or multiple injections. We have been unable to find any clinical reports of central nervous system or cardiovascular toxicity due to excessive systemic LA levels. This is an important consideration as substantial amounts of LA are required for bolus dosing and infusion with bilateral PVB. We recommend the use of levobupivacaine or ropivacaine for bilateral block. The maximum plasma concentration (Cpmax) obtained with a bolus of bupivacaine 0.5% (20 ml) was 1.45 (0.32) mg ml 21 with a median (range) time to Cpmax (tcpmax) of 25 (10 60) min. 39 After the initial peak with the bolus injection, there was a gradual increase to a mean (SEM) peak concentration of 4.92 (0.7) mg ml 21 at 48 h (5 96) with no clinical toxicity. Similar levels were found in a previous study using these methods, but with a higher concentration of the (less toxic) S-enantiomer. 40 An investigation measured bupivacaine plasma concentrations during a 5 day postoperative infusion of racemic bupivacaine using this same dose regime. 41 Despite successive increases in total plasma bupivacaine concentration, with an average plasma level at or close to what is generally believed to be the threshold for early systemic toxicity (2.5 mg ml 21 ) on postoperative day 4, the free unbound concentration of bupivacaine was stable throughout the 5 day period at a non-toxic level of 0.1 mg ml 21. This was explained by a simultaneous increase in alpha-1 acid glycoprotein, the main protein responsible for protein binding of LA, as part of the postoperative acute phase response after surgical trauma. A case series of 20 paediatric patients with a median age range of 5.3 weeks given a bolus of bupivacaine 0.25% (1.25 mg kg 21 ) followed by infusion of bupivacaine 0.25% (0.5 mg kg 21 h 21 ) for 24 h for post-thoracotomy pain relief found safe peak concentrations during the loading dose and during infusion. 42 A study of 22 even smaller infants 166

4 Bilateral paravertebral blocks Table 3 Bilateral applications. P, prospective; R, randomized; T, trial; GA, general anaesthesia; Bilat, bilateral; Retro, retrospective; Bupiv, bupivacaine; Ropiv, ropivacaine; Lido, lidocaine; PONV, postoperative nausea and vomiting; sig, significant; CVS, cardiovascular system; GIT, gastrointestinal tract; Stim, nerve stimulator-guided; US, ultrasound-guided; epi, epinephrine; PC, personal communication (S. Desai, 2010) Ref. Indication Type of study, patients Techniques Outcome Adverse effects 9 Thorax and abdominal surgery PRT, 61 (368 blocks) 19 Ventral hernia repair P comparative 30 vs PVB each side Block spread better with multiple injections. Pain not relevant to this study Stim T9 T11 lido, epi, bupiv, fentanyl, and clonidine 60 Abdominoplasty 4 case reports, GA Ropiv between T6 and T10 61 Day-case breast augmentation 62 Abdominal aortic aneurysm P, 100 Bilat T4, 2 15 ml ropiv 0.75%, max 225 mg+sedation P case series, 8 GA T10 bolus bupiv 0.5% (12.5 ml) bilat then continuous infusion for 4 days 63 Labour Case report, 4 4 levels T10 L1. Each bupiv 0.5% (4 ml) and epi 1: , then 2 blocks then 1 64 Bilateral reduction mammoplasty 46 Laparoscopic cholecystectomy Case report, 1 GA PR. 30 BPVB and GA vs 30 GA 65 Bilateral thoracotomy Case study, One 11 months old. GA 47 Adults and children, mixed major GIT surgery 66 Major intra-abdominal surgery 67 Myofascial chronic postoperative thoracic pain PC Thoraco-abdominal lung, gut, and vascular surgery P study of complication rates, 196. No GA Bilat catheters T3. 15 ml 0.5% ropiv and epi then infusions 0.2% Stim BPVB T5 6 lido, epi, bupiv, fentanyl, and clonidine Bupiv 0.25%, 0.5 ml kg 21 bilat then infusion 0.125% 0.2 ml kg 21 h 21 for 60 h Multiple levels, stim. Lido, epi, bupiv, fentanyl and clonidine mixture Hospital stay shorter with PVB [2.3 days (SD 1.3) vs (4.1) (3.0)]. Less pain and supplemental analgesia with PVB (P,0.001). PONV less (3.3% vs 26.7%) (P,0.05). PVB good patient acceptance in 90% Postop opiates avoided Successful surgical anaesthesia/ postop analgesia: 87/94%. Good pain scoring. PONV 10%. Vasopressors in 6% Good CVS stability with aortic clamping and declamping. Good pain control in all Abdominal pain relieved, deep pelvic and rectal pain continued. CVS stable No postoperative pain or need for analgesics Pain scores sig less with BPVB (P,0.05) at 6, 12, 24, 36, 48, and 72 h. Supplemental analgesics sig less (P,0.05). Less PONV Effective pain relief. Serum bupiv concentrations below toxic levels See Table 5 P, 101, GA Ropiv bolus then infusion Probably improved postop pain and reduced opioid requirement Case report, 1 Stim bupiv, clonidine Total pain relief with repeated injections 24 m follow-up Retro, 8, GA US, bolus 0.25% bupiv then infusions Excellent pain relief on deep breathing and coughing in all. Seven mobilized early One preconvulsion, 10 bradycardia, hypotension Accidental sedation in 1 undergoing thoracotomy reported satisfactory concentrations. 43 The median age was 1.5 weeks with a range of 1 day to 20.4 weeks and the doses of bupivacaine given were 0.25% (1.25 mg kg 21 ) followed by bupivacaine 0.125% with epinephrine at a rate of 0.2 ml kg 21 h 21 for 48 h. In a comparison of plain bupivacaine 0.25% with bupivacaine 0.25% with epinephrine 1: given as a bolus dose of 1 mg kg 21 to thoracotomy patients, 44 the Cpmax ranged from to 1.08 mg ml 21 (median 0.705) in the bupivacaine with epinephrine group, compared with mg ml 21 (median 0.918) in the plain bupivacaine group. The median (range) tcpmax was 5 min (5 20) for both groups. Lowering of maximal plasma bupivacaine concentrations with epinephrine containing solutions and is obviously desirable in bilateral PVB. The use of adjuncts with LA for PVB for patients undergoing thoracotomy has recently been reviewed. 45 Opioids 167

5 Richardson et al. Table 4 Techniques Technique Reference Loss of resistance 68 Simple advancement over or under transverse 18 process for cm Nerve stimulator 9846 Pressure monitoring 69 X-ray direct vision Used in chronic pain Direct vision at thoracotomy/thoracoscopy Ultrasound-guided Table 5 Complication rates (%). *Nerve stimulator used for block placement Multicentre prospective 367 children and adults 73 Prospective 620 adults, 42 children 47 Unilateral block, n5466 (%) Bilateral block, n5196 (%) Failure rate * Hypotension (3.9) 7 (3.6) Vascular (5.4) 17 (8.7) puncture Pleural puncture (0.8) 4 (2.0) Pneumothorax (0.2) 2 (1.0) Urinary retention Not reported Not reported Haematoma 9 (1.9) 6 (3.1) Signs of epidural 5 (1.1) 1 (0.5) or intrathecal spread Pain at puncture 5 (1.1) 3 (1.5) site Total spinal One case report 74 and clonidine may be helpful in improving the block quality and duration. The extent of dermatomal spread of LA is variable. In children, lidocaine 1% with epinephrine was found to spread on average 0.07 ml kg 21 segment In adults, mean spread was found to be 2 ml segment 21 for lidocaine 1% 24 and 3 ml segment 21 for bupivacaine 0.5%. 23 However, another study 50 found no correlation between spread and dose. A study using radio-opaque dye suggested ml kg 21 segment There are a number of potential or relative contraindications to the use of PVB, including coagulation disorders and anticoagulation, tumour in the PVS, and empyema. General anaesthesia is not a contra-indication. In the presence of chest deformity, the use of imaging is recommended. No additional nursing skills or observations are necessary other than those required for the routine care of postoperative patients. PVB is not an indication for admission to high-dependency care. Side-effects and complications Studies and reviews of the incidence of sideeffects and complications generally agree that these are low and acceptable. There are three specific potential drawbacks to the bilateral use of PVB. These are the potential for high blood concentrations of LA and the risk of hypotension and pneumothorax. Data relating to LA toxicity have been presented above. The overall success rate for unilateral blocks is 94%. 47 In two studies measuring cardiovascular variables in the absence of fluid loading, one with a unilateral mean somatic and sympathetic block of five and eight dermatomes, respectively, 23 and the other resulting in 12 and six dermatomes, respectively, 24 found no clinically significant postural changes in the variables measured. These studies are supportive of the cardiovascular safety when used bilaterally. We did not find any clinical reports of morbidity due to profound sympathetic blockade. With unilateral PVB, the risk of accidental pleural puncture was 0.8% and the subsequent development of a pneumothorax occurred in 0.5% of the total patient population This risk compares favourably with other regional anaesthesia techniques, for example, intercostal nerve blocks, and is thus not a strong argument for avoiding this technique. A recalculation of the pneumothorax rate from an earlier study 47 based on the number of blocks carried out rather than by patients treated, suggested that the worst risk rate of a bilateral pneumothorax would be 1 in A study of more than 1000 PVB reported no pneumothoraces using the classical multilevel approach with caudal angulation of the needle 1 cm below the transverse process. 52 It is recommended that inferior angulation of the needle is important in providing a more firm endpoint and reducing risk. 51 Urinary problems are very rare, 35 and even with bilateral PVB, this has not been reported (Table 5). Discussion We advocate that bilateral PVB be considered as a reasonable replacement for epidural analgesia for midline surgery. Where central neural blocks are contraindicated, for example, in anti-coagulated patients, those with systemic sepsis, or where epidural catheterization is technically impossible, bilateral PVB is a suitable alternative. This decision is aided by the increasing use of spontaneous breathing techniques with a laryngeal mask, as opposed to paralysis and intermittent positive pressure ventilation, which may reduce the risks of a significant pneumothorax. Excellence in anaesthesia and perioperative medicine demands the use of regional anaesthesia and analgesia in any situation where pain and the neuroendocrine 168

6 Bilateral paravertebral blocks stress response to trauma makes significant demands. This must balance the effect of surgical trauma and the overall condition of the patient. Thus, in a patient with significant organ damage, it would support the decision to use a regional nerve block even for more minor procedures. The type of block and when to apply it requires maturity of judgement. Published data indicate that PVB is effective and safe, although more data on bilateral PVBs is required. New data suggest additional benefits of this block. Tissue oxygen tension in latissimus dorsi flaps for breast reconstruction has been shown to be increased by PVB as opposed to opioid analgesia. 53 Chronic pain after thoracotomy 29 and breast surgery has been shown to be reduced. 28 Breast cancer recurrence may be lowered. 54 Preservation of postoperative pulmonary function and prevention of pulmonary complications are impressive The relationship of regional anaesthesia to wound healing, chronic postoperative pain, and cancer recurrence rates with this and other blocks is important. PVBs are relatively simple to perform, but nerve stimulation and more recently refinement of ultrasound afford the practitioner greater confidence. 55 With few contraindications, no requirement for additional postoperative care, and a low side-effect profile (especially hypotension), this form of afferent blockade readily offers a basis for accelerated postoperative mobilization regimes. Conflict of interest None declared. References 1 Bonica JJ. 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7 Richardson et al. analgesia does not affect vascular endothelial growth factor and prostaglandin E 2. Anesth Analg 2005; 100: Hall GM, Desborough JP. Interleukin-6 and the metabolic response to surgery. Br J Anaesth 1992; 69: Richardson J, Sabanathan S, Mearns AJ, et al. Efficacy of preemptive analgesia and continuous extrapleural intercostal nerve block on postthoracotomy pain and pulmonary mechanics. J Cardiovasc Surg 1994; 35: Davies RG, Myles PS, Graham JM. A comparison of the analgesic efficacy and side effects of paravertebral vs epidural blockade for thoracotomy a systemic review and meta-analysis of randomized trials. Br J Anaesth 2006; 96: Kaiser AM, Zollinger A, De Lorenzi D, et al. Prospective randomised comparison of extrapleural versus epidural analgesia for postthoracotomy pain. Ann Thorac Surg 1998; 66: Richardson J, Sabanathan S, Shah R. Postthoracotomy spirometric lung function: the effect of analgesia. A review. 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Bilateral thoracic paravertebral block for abdominoplasty. J Clin Anesth 2008; 1: Cooter RD, Rudkin GE, Gardiner SE, Phty B. Day case breast augmentation under paravertebral blockade. A prospective study of 100 patients. Aesth Plast Surg 2007; 31: Richardson J, Vowden P, Sabanathan S. Bilateral paravertebral analgesia for major abdominal vascular surgery: a preliminary report. Anaesthesia 1995; 50: Nair V, Henry R. Bilateral paravertebral block: a satisfactory alternative for labour analgesia. Can J Anaesth 2001; 48: Buckenmaier CC III, Steele SM, Nielsen KC, Martin AH, Klein SM. Bilateral continuous paravertebral catheters for reduction mammoplasty. Acta Anaesthesiol Scand 2002; 46: Karmakar MK, Booker PD, Franks R. Bilateral continuous paravertebral block used for postoperative analgesia in an infant having bilateral thoracotomy. Paediatr Anaesth 2007; 7: Burns DA, Ben-David B, Chelly JE, Greensmith JE. 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8 Bilateral paravertebral blocks 71 Luyet C, Eichenberger U, Greif R, et al. Ultrasound-guided paravertebral puncture and placement of catheters in human cadavers: an imaging study. Br J Anaesth 2009; 102: Pusch F, Wilding E, Klimscha W, Weinstabl C. Sonographic measurement of needle depth in paravertebral blocks in women. Br J Anaesth 2000; 85: Lönnqvist PA, MacKenzie J, Soni AK, Conacher ID. Paravertebral blockade: failure rate and complications. Anaesthesia 1995; 50: Gay GR, Evans JA. Total spinal anaesthesia following lumbar paravertebral block: a potentially lethal complication. Anesth Analg 1971; 50: