Thoracic paravertebral block: a method of pain control

Comparison of the Efficacy Between Ultrasound-Guided Paravertebral Block and Erector Spinae Block for Postoperative Analgesia in Percutaneous Nephrolithotomy Using Levobupivacaine: A Prospective and Randomized Study

Introduction Various techniques have been developed in the current era of regional anesthesia practice. With the advent of ultrasound, the visualization of needle and pleura in real time enables a better outcome with negligible adverse events. This study was designed to compare the efficacy between ultrasound-guided erector spinae plane block (ESPB) and paravertebral block (PVB) in percutaneous nephrolithotomy (PCNL) for the duration of postoperative analgesia with levobupivacaine, a local anesthetic with higher lipid solubility, making it more potent and resulting in a longer duration of action. Methods This prospective randomized single-blinded study enrolled 50 patients of ASA grades I and II, aged between 20 and 60 years, who were scheduled for PCNL under general anesthesia. Patients were divided into two groups of 25 each: group ESPB and group PVB, and 25 mL of 0.25% levobupivacaine was administered to both groups. They were primarily evaluated for the duration of postoperative analgesia. Total rescue analgesic requirements, hemodynamic parameters, and any adverse effects were also assessed. Results Both ESPB and PVB provided a significant duration of analgesia postoperatively. Demographic characteristics in both groups were comparable. The duration of postoperative analgesia in group ESPB was 746 ± 58.6 minutes when compared to group PVB, which is 768 ± 68.6 minutes (p = 0.08). Intravenous (IV) paracetamol was used as a rescue analgesic. The doses used were also comparable in both groups, with the visual analog score (VAS) being high after around 12 hours of surgery. The total rescue analgesic requirement was similar in both groups (group ESPB, 2.0 ± 1.6; group PVB, 2.2 ± 1.4; p = 0.51). There were no significant hemodynamic or other adverse effects in either group. Conclusion We conclude that both ESPB and PVB using isobaric levobupivacaine 0.25% as a local anesthetic are equally efficacious in providing effective postoperative analgesia in patients undergoing PCNL under general anesthesia.

A Comparison of Analgesia After a Thoracoscopic Lung Cancer Operation with a Sustained Epidural Block and a Sustained Paravertebral Block: A Randomized Controlled Study

INTRODUCTION

This study aimed to compare the challenge of puncture and catheterization and the effect of postoperative analgesia of ultrasound-guided continuous thoracic paravertebral block and the continuous epidural analgesia in patients receiving thoracoscopic surgery for lung cancer.

METHODS

One-hundred and fifty patients received elective unilateral thoracoscopic surgery for lung cancer and were randomized into three groups; test group 1 (T group), test group 2 (P group), and the control group (E group). Both of the test groups received ultrasound-guided continuous thoracic paravertebral block (TPVB) while the control group received continuous epidural analgesia. After the operation, all the patients in the test groups received the same postoperative analgesia; loading dose 0.5 mg kg^-1, background dose 0.25 mg kg^-1 h^-1, patient controlled analgesia (PCA) 0.25 mg kg^-1, and a locking time of 60 min, while the patients in the control group received a loading dose of 5 ml, a background dose of 5 ml h^-1, and a locking time of 20 min. The outcomes of this study were the success rate of the puncture and catheter placement, the blocked segments, numerical rating scale (NRS) scores at rest and during coughing, and the segments with reduced or lost cold and pinpricking sensation.

RESULTS

The success rates of the puncture and catheterization in group T were the highest. Compared with group P, the failure rate of the puncture in group E was lower (p < 0.05), but the success rate of catheterization was higher (p < 0.05). The puncture time in group T was the shortest; there was no difference between group E and group T. The time of catheterization in group P was the longest, this was followed by group T, and was the fastest in group E. The stable time of the block level in group E was shorter than that in groups P and T, but was similar between groups P and T. The block level of all three groups in the 4 h postoperative period was similar (p > 0.05), while the 4 h postoperative levels of groups P and T were reduced significantly (p < 0.05).

CONCLUSION

The continuous analgesia technique of paravertebral space catheterization cannot replace the continuous epidural analgesia in thoracoscopic lung cancer surgery as the latter technique is still considered to be the gold standard.

TRIAL REGISTRATION

China Clinical Trial Registration Center identifier ChiCTR1900020973.

Chest Trauma: Current Recommendations for Rib Fractures, Pneumothorax, and Other Injuries

Purpose of Review

This article provides an overview of the common and important chest injuries that the anesthesiologist may encounter in patients following trauma including blunt injury, pneumothorax, hemothorax, blunt aortic injury, and blunt cardiac injury.

Recent Findings

Rib fractures are frequently associated with chest injury and are associated with significant pain and other complications. Regional anesthesia techniques combined with a multimodal analgesic strategy can improve patient outcomes and reduce complications. There is increasing evidence for paravertebral blocks for this indication, and the myofascial plane blocks are a popular emerging technique. Recent changes to recommended management of tension pneumothorax are also described.

Summary

Chest trauma is commonly encountered, and anesthesiologists have the potential to significantly improve morbidity and mortality in this group of patients.

Paravertebral block for radiologically inserted gastrostomy tube placement in amyotrophic lateral sclerosis

INTRODUCTION

Radiologically inserted gastrostomy (RIG) placement in patients with amyotrophic lateral sclerosis (ALS) carries risks related to periprocedural sedation and analgesia. To minimize these risks, we used a paravertebral block (PVB) technique for RIG placement.

METHODS

We retrospectively reviewed patients with ALS undergoing RIG placement under PVB between 2013 and 2017.

RESULTS

Ninety-nine patients with ALS underwent RIG placement under PVB. Median (range) age was 66 (28 to 86) years, ALS Functional Rating Scale-Revised score was 27 (6 to 45), and forced vital capacity was 47% (8%-79%) at time of RIG placement. Eighty-five (85.9%) patients underwent RIG placement as outpatients, with a mean postanesthesia care unit stay of 2.3 hours. The readmission rate was 4% at both 1 and 30 days postprocedure.

DISCUSSION

PVB for RIG placement has a low rate of adverse events and provides effective periprocedural analgesia in patients with ALS, the majority of whom can be treated as outpatients.

Effect of Perineural Dexamethasone With Bupivacaine in Single Space Paravertebral Block for Postoperative Analgesia in Elective Nephrectomy Cases: A Double-Blind Placebo-Controlled Trial

Various analgesic modalities have been tried to prolong the duration and to improve the quality of postoperative analgesia for the early rehabilitation and discharge from hospital after nephrectomy. Using local anaesthetic along with perineural steroids as adjuvant may prove promising for peripheral nerve block, especially paravertebral block (PVB). This article aims to assess the efficacy of dexamethasone with bupivacaine as adjuvant for single bolus injection of thoracic PVB in patients undergoing elective nephrectomy. Sixty patients of American Society of Anesthesiologists physical status I and II were randomly assigned to 2 groups of 30 patients each. Group D patients received 8 mg (2 mL) of dexamethasone mixed to 18 mL of 0.25% bupivacaine, whereas patients in group B received 18 mL of 0.25% bupivacaine and 2 mL of 0.9% saline as placebo to make a total volume of 20 mL infiltrated in PVB. Degree of analgesia achieved and duration of analgesia were recorded in each group along with total dose requirement of rescue analgesic and side effects in first 24 hours postoperatively. Group D patients with dexamethasone had VAS score of 0-3 after 09 minutes of block up to 610.48 ± 12.24 minutes and after 16 minutes up to 402.34 ± 28.12 minutes in another group B patient, respectively. The total dose of intravenous fentanyl in the first 24 hours postoperatively in group D was 98.6 ± 14.14 μg as compared with 147.6 ± 18.22 μg in group B. No other significant side effects were noted except for nausea and vomiting in 5 patients of placebo group. Dexamethasone, along with bupivacaine as adjunct for thoracic PVB, helps in improving the quality and enhancing the postoperative analgesia duration in patients undergoing nephrectomy.

Ultrasound-guided single- vs double-level thoracic paravertebral block for postoperative analgesia in total mastectomy with axillary clearance

OBJECTIVES

Thoracic paravertebral block (TPVB) for breast surgery reduces acute and chronic postoperative pain. Using ultrasound for administering the block makes it easier, with its administration at multiple levels decreasing the number of unblocked segments. We conducted this study to evaluate the efficacy and safety of single- vs double-level ultrasound-guided TPVB in patients undergoing total mastectomy with axillary clearance under general anesthesia.

DESIGN

This is a prospective, randomized study.

SETTING

Recovery room and operation theater.

PATIENTS

Sixty ASA I and II patients, aged 18 to 60 years, who were scheduled to undergo total mastectomy with axillary clearance under general anesthesia were enrolled in the study.

INTERVENTIONS

Patients received either single- (group S) or double-level (group D) ultrasound-guided TPVB at T4 or at T2 and T5 levels, respectively, using 0.3 mL/kg of 0.5% ropivacaine.

MEASUREMENTS

Primary outcome measure was 24-hour analgesic consumption, and secondary outcomes included number of segments blocked, postoperative pain scores, time to first request for rescue analgesic, and any side effects.

RESULTS

The mean total amount of rescue analgesic given in group S was 175.3 ± 70 mg and in group D was 115.7 ± 48 mg (P = .002). Median number of segments showing less sensation to pinprick was 3 in group S and 4 in group D (P < .001). The mean time to first request for rescue analgesic was 533 ± 124 minutes in group S and was 611 ± 214 minutes in group D (P = .118).

CONCLUSION

Patients receiving double-level TPVB had significantly less 24-hour analgesic consumption in the postoperative period than those in the single-level TPVB group. This could be due to decreased pain sensation to pinprick in significantly greater number of segments in the double-level TPVB group.

Thermal imaging evaluation of paravertebral block for mastectomy in high risk patient: case report

Thoracic paravertebral block is the technique of injecting local anesthetic adjacent to the thoracic vertebra close to where the spinal nerves emerge from the intervertebral foramina. It is effective in treating acute and chronic pain of unilateral origin from the chest and abdomen. This technique causes pain relief with pulmonary function preservation and great hemodynamic stability. 66 year old woman (156 cm, 80 kg, BMI 32) with chronic right heart failure, hypertension and obesity, on chronic oxygen therapy was presented for elective mastectomy due to breast cancer. She suffered from severe COPD and also bullous emphysema. FVC 1.59 l; FEV1 0.55 l; FEV1%FVC 34.6. The paravertebral block was performed using the multi-shot percutaneous technique with additional light general anesthesia. For confirmation, of proper analgesia range, control of temperature changes, using FLIR i7 infrared camera, was performed. Control photos were made 20 min after the blockade and then 10 min later. Infrared photo showed rise of temperature reading in every marked region. There were no hemodynamic and pulmonary complications postoperatively. Paravertebral block in combination with sedation creates excellent conditions for breast surgery procedures. Additional temperature changes monitoring performed with infrared camera may confirm proper range of analgesia needed to perform surgery. Great cardiovascular stability and very good pulmonary function preservation make this method excellent for high risk patients. Low complication rate is additional advantage. In our opinion this method is recommendable.

Continuous paravertebral infusion of ropivacaine with or without fentanyl for pain relief in unilateral multiple fractured ribs

Background:

Continuous thoracic paravertebral block (TPVB) provides effective analgesia for unilateral multiple fractured ribs (MFR). However, prolonged infusion of local anaesthetic (LA) in high doses can predispose to risk of LA toxicity, which may be reduced by using safer drugs or drug combinations. This study was conducted to assess efficacy and safety of paravertebral infusion of ropivacaine and adrenaline with or without fentanyl to provide analgesia to patients with unilateral MFR.

Methods:

Thirty adults, having ≥3 unilateral MFR, with no significant trauma outside chest wall, were studied. All received bolus of 0.5% ropivacaine 0.3 ml/kg through paravertebral catheter, followed by either 0.1-0.2 ml/kg/hr infusion of ropivacaine 0.375% with adrenaline 5 μg/ml in group RA or ropivacaine 0.2% with adrenaline 5 μg/ml and fentanyl 2 μg/ml in group RAF. Rescue analgesia was provided by IV morphine.

Results:

Statistical analysis was performed using unpaired Student t-test, Chi-square test and repeated measures ANOVA. After TPVB, VAS scores, respiratory rate and PEFR improved in both groups with no significant inter-group differences. Duration of ropivacaine infusion, morphine requirements, length of ICU and hospital stay, incidence of pulmonary complications and opioid-related side-effects were similar in both groups. Ropivacaine requirement was higher in group RA than group RAF. No patient showed signs of LA toxicity.

Conclusion:

Continuous paravertebral infusion of ropivacaine 0.375% with adrenaline 5 μg/ml at 0.1-0.2 ml/kg/hr provided effective and safe analgesia to patients with unilateral MFR. Addition of fentanyl 2 μg/ml allowed reduction of ropivacaine concentration to 0.2% without decreasing efficacy or increasing opioid-related side-effects.

The location of paravertebral catheters placed using the landmark technique

The aim of this prospective clinical study was to evaluate the location of paravertebral catheters that were placed using the classical landmark puncture technique and to correlate the distribution of contrast dye injected through the catheters with the extent of somatic block. Paravertebral catheter placement was attempted in 31 patients after video-assisted thoracic surgery. In one patient, an ultrasound-guided approach was chosen after failed catheter placement using the landmark method. A fluoroscopic examination in two planes using contrast dye was followed by injection of local anaesthetic and subsequent clinical testing of the extent of the anaesthetised area. In nine patients (29%), spread of contrast dye was not seen within the paravertebral space as intended. Misplaced catheters were in the epidural space (three patients), in the erector spinae musculature (five patients), and in the pleural space (one patient). There was also a discrepancy between the radiological findings and the observed distribution of loss of sensation. We have demonstrated an unacceptably high misplacement rate of paravertebral catheters using the landmark method. Additional research is required to compare the efficacy and safety of continuous paravertebral block using ultrasound-guided techniques or surgical inserted catheters.

Post-operative pain and analgesic requirements after paravertebral block for mastectomy: A randomized controlled trial of different concentrations of bupivacaine and fentanyl

Background:

Paravertebral block (PVB) is useful for post-operative analgesia after breast surgery. Bupivacaine is used for PVB at higher concentrations (0.5%), which may lead to systemic toxicity after absorption. Therefore, we proposed to evaluate the efficacy of lower concentrations of bupivacaine with and without fentanyl for thoracic PVB in patients undergoing surgery for carcinoma breast.

Methods:

Forty-eight patients scheduled for surgery for breast cancer were enrolled in this prospective, randomized, double-blinded, placebo-controlled trial and were allocated to one of four groups: 0.25% bupivacaine with epinephrine 5 mcg/ ml, 0.25% bupivacaine + epinephrine 5 mcg/ ml with 2 mcg/ml fentanyl, 0.5% bupivacaine + epinephrine 5 mcg/ml or isotonic saline. PVB was performed and 0.3 ml/kg of the test drug was administered before induction of general anaesthesia. The primary outcome assessed was post-operative analgesic requirement for a period of 24 h. Secondary outcome measures were post-operative pain scores at rest and on movement of the arm, latency to first opioid, post-operative nausea and vomiting, quality of sleep, ability to move arm and patient satisfaction.

Results:

The patient characteristics and anaesthetic technique were comparable among the groups. The rescue analgesic consumption as well as cumulative pain scores at rest and on movement were significantly less in 0.25% bupivacaine+epinephrine with fentanyl and 0.5% bupivacaine+epinephrine groups (P<0.05). The average duration of analgesia was found to be 18 h after either 0.25% bupivacaine with epinephrine+fentanyl or 0.5% bupivacaine with epinephrine.

Conclusions:

Lower concentrations of bupivacaine can be combined with fentanyl to achieve analgesic efficacy similar to bupivacaine at higher concentrations, decreasing the risk of toxicity in PVB.

Paravertebral blocks

PVB remains an underused block. It is easy to perform reliable and effective blocks for a wide variety of applications both for acute or chronic pain. As evidence continues to be published showing the advantages of PVB versus traditional methods of pain control, it is hoped that PVB will become part of the standard repertoire of blocks used in teaching hospitals and in private practice.

Paravertebral blocks

Paravertebral blocks have been demonstrated to represent an interesting alternative to epidural, especially for the management of perioperative and trauma pain. Initially performed mostly as single-shot blocks for breast surgery, thoracotomy, and hernia repairs in adults and children, presently these blocks are also used for placement of a paravertebral catheter, either unilateral or bilateral. Although complications associated with the performance of these blocks are infrequent, the use of ultrasound-guided approaches, which allow performing the block under direct vision, is becoming the standard in most groups performing these blocks routinely.

Unintended epidural placement of a thoracic paravertebral catheter in a patient with severe chest trauma

OBJECTIVE

Severe pain can lead to ventilatory compromise in patients with multiple rib fractures. Regional anesthetic techniques, including continuous thoracic paravertebral and thoracic epidural blocks, can be useful in reducing this pain and subsequent morbidity due to respiratory compromise. Thoracic paravertebral block can result in significant complications. Presumed epidural spread of injected medication has been described with thoracic paravertebral block. High-quality radiographic images of an attempted placement of a thoracic paravertebral catheter in the epidural space have not been reported. We present these images to highlight the occurrence of this complication.

SETTINGS AND PATIENTS

In this case, we report an attempted placement of a thoracic paravertebral catheter that passed into the epidural space. High-fidelity, three-dimensional computer tomography images and the management of the unintended epidural catheterization are presented.

RESULTS AND CONCLUSIONS

In the setting of severe chest trauma, the potential risk of unintended placement of an intended thoracic paravertebral catheter in the epidural space is graphically illustrated as a potential risk of this procedure.

Unrecognized contralateral intrapleural catheter: bilateral blockade may obscure detection of failed epidural catheterization

Thoracic epidural analgesia has been widely used to reduce both postoperative and posttraumatic pain. We describe a case of inadvertent right-sided interpleural catheter placement and pneumothorax during attempted epidural catheter placement for left-sided rib fractures that went unrecognized because of bilateral blockade and adequate analgesia.

Bilateral paravertebral blockade for conventional cardiac surgery

This prospective observational study aimed to assess the feasibility and efficacy of bilateral continuous paravertebral blockade combined with general anaesthesia in "on-pump" cardiac surgery. One hundred and eleven elective patients had two paravertebral catheters inserted: one either side of the midline within 2.5 cm of the spinous process of the third or fourth thoracic vertebrae, through which a mixture of ropivacaine and fentanyl was infused during and after surgery. In the first 47 patients, haemodynamic and analgesia data were recorded. In all patients, time to tracheal extubation, length of stay in the intensive care unit and the hospital, morbidity and mortality, and any complication attributable to the regional blockade were recorded. The technique was associated with good haemodynamic stability, good postoperative analgesia and short times to tracheal extubation, with few significant complications.

Acute pain management of patients with multiple fractured ribs

BACKGROUND

Multiple rib fracture causes severe pain that can seriously compromise respiratory mechanics and exacerbate underlying lung injury and pre-existing respiratory disease, predisposing to respiratory failure. The cornerstone of management is early institution of effective pain relief, the subject of this review.

METHODS

A MEDLINE search was conducted for the years 1966 through and up to December 2002 for human studies written in English using the keywords "rib fractures", "analgesia", "blunt chest trauma", "thoracic injury", and "nerve block". The reference list of key articles was also searched for relevant articles. The various analgesic techniques used in patients with multiple fractured ribs were summarized.

RESULTS

Analgesia could be provided using systemic opioids, transcutaneous electrical nerve stimulation or non steroidal anti-inflammatory drugs. Alternatively, regional analgesic techniques such as intercostal nerve block, epidural analgesia, intrathecal opioids, interpleural analgesia and thoracic paravertebral block have been used effectively. Although invasive, in general, regional blocks tend to be more effective than systemic opioids, and produce less systemic side effects.

CONCLUSION

Based on current evidence it is difficult to recommend a single method that can be safely and effectively used for analgesia in all circumstances in patients with multiple fractured ribs. By understanding the strengths and weaknesses of each analgesic technique, the clinician can weigh the risks and benefits and individualize pain management based on the clinical setting and the extent of trauma.

Continuous thoracic paravertebral infusion of bupivacaine for pain management in patients with multiple fractured ribs

STUDY OBJECTIVE

To evaluate the efficacy of a continuous thoracic paravertebral infusion of bupivacaine for pain management in patients with unilateral multiple fractured ribs (MFR).

DESIGN

Prospective nonrandomized case series.

SETTING

Multidisciplinary tertiary hospital.

PATIENTS

Fifteen patients with unilateral MFR.

INTERVENTIONS

Insertion of a catheter into the thoracic paravertebral space. We administered an initial injection of 0.3 mL/kg (1.5 mg/kg) bupivacaine 0.5% with 1:200,000 epinephrine followed 30 min later by an infusion of bupivacaine 0.25% at 0.1 to 0.2 mL/kg/h for 4 days.

MEASUREMENTS AND RESULTS

The following parameters were measured during the initial assessment before thoracic paravertebral block (TPVB), 30 min after the initial injection, and during follow-up on day 1 and day 4 after commencing the infusion of bupivacaine: visual analog pain score at rest and during coughing; respiratory rate; arterial oxygen saturation (SaO(2)); bedside spirometry (ie, FVC, FEV(1), FEV(1)/FVC ratio, and peak expiratory flow rate [PEFR]); arterial blood gas measurements; and O(2) index (ie, PaO(2)/fraction of inspired oxygen ratio). There were significant improvements in pain scores (at rest, p = 0.002; during coughing, p = 0.001), respiratory rate (p < 0.0001), FVC (p = 0.007), PEFR (p = 0.01), SaO(2) (p = 0.04), and O(2) index (p = 0.01) 30 min after the initial injection, which were sustained for the 4 days that the thoracic paravertebral infusion was in use (p < 0.05). PaCO(2) did not change significantly after the initial injection, but on day 4 it was significantly lower than the post-TPVB value (p = 0.04). One patient had an inadvertent epidural injection, and another developed transient ipsilateral Horner syndrome with sensory changes in the arm. No patient exhibited clinical signs of inadvertent intravascular injection or local anesthetic toxicity.

CONCLUSION

Our results confirmed that continuous thoracic paravertebral infusion of bupivacaine is a simple and effective method of providing continuous pain relief in patients with unilateral MFR. It also produced a sustained improvement in respiratory parameters and oxygenation.

Continuous infusion is superior to bolus doses with thoracic paravertebral blocks after thoracotomies

OBJECTIVES

This study was designed to determine whether a continuous thoracic paravertebral infusion of bupivacaine (continuous TPVI) offers a higher quality of analgesia than a bolus regimen after thoracotomy.

DESIGN

A prospective and randomized study.

SETTING

It was conducted by an anesthesiology and pain clinic department in a university hospital.

PARTICIPANTS

Thirty patients were included in this study.

INTERVENTIONS

As postoperative analgesia, the patients received either 20 mL of 0.375% bupivacaine every 6 hours (n = 15; bolus group), or a loading dose of 15 mL of 0.375% bupivacaine, plus an infusion of 5 mL of 0.25% bupivacaine every hour (n = 15; infusion group).

MEASUREMENTS AND MAIN RESULTS

Pain intensity was assessed at rest and on movement (coughing) at 0, 1, 4, 10, 20, and 48 hours by means of the visual analog scale. The need for additional rescue analgesia, bupivacaine plasma concentration in the infusion group, blockade level (pinprick), and vital signs were also recorded. There were no significant differences regarding the additional rescue analgesia, vital signs, and pinprick level. However, the pain scores were significantly higher in the bolus group at rest and on movement (p < 0.01). The bupivacaine plasma concentration was low with a Cmax of 1.841 +/- 0.20 micrograms/mL at 15 hours. No systemic toxicity or other side effects were seen.

CONCLUSION

Results suggest that continuous TPVI provides better pain control than the bolus regimen after this kind of surgery.

Thoracic paravertebral analgesia

Thoracic paravertebral nerve blockade, although once widely practised, has now only a few centres which contribute to the literature. Data production has, however, continued and this review correlates this new information with existing knowledge. Its history, taxonomy, anatomy, indications, techniques, mechanisms of analgesia, efficacy, contraindications, toxicity, side effects and complications are reviewed. Thoracic paravertebral analgesia is advocated for surgical procedures of the thorax and abdomen, especially wherever the afferent input is predominantly unilateral eg. thoracotomy, cholecystectomy and nephrectomy. It is also of benefit in the prevention and management of chronic pain. It is a simple undertaking with impressive efficacy. Plasma local anaesthetic levels are acceptable and its side effect and complication rates are low. No mortality has been reported. For unilateral surgery of the chest or truck, thoracic paravertebral analgesia should be considered as the afferent block of choice. For bilateral surgery, its efficacy may be limited by the doses of local anaesthetic which could safely be used and further study in this area in particular is required. This form of afferent blockade deserves greater consideration and investigation.

[Analgesia after thoracotomy by extrapleural administration of continuous bupivacaine]

This study was aimed to assess the efficiency and the side effects of a continuous administration of bupivacaine into the paravertebral space. Twenty patients, ranked ASA 2 or 3, with a mean age of 57.9 years, and having had a posterolateral thoracotomy for resection of lung tissue, were randomly assigned to one of two groups, B or C. At the end of the surgical procedure, a 22 gauge catheter was inserted into the paravertebral extrapleural space, at T4 levels As soon as pain occurred during recovery (T0), the patients were given two-hourly intravenous boluses of buprenorphine. The patients in group B were also given, through the paravertebral catheter, a 20 ml bolus of 0.25% bupivacaine, followed by a continuous steady rate infusion (10 ml.h-1). Group C patients were given normal saline in the same way. All patients could improve their analgesia with 0.05 ml boluses of buprenorphine given by an auto-analgesia pump (Pharmacia). The following parameters were assessed during the 72 h which followed the first injection: pain with a visual analogic scale, quality of sedation (5 grades), heart and breathing rate, systolic and diastolic blood pressure, arterial blood gases. In group B, plasma bupivacaine concentrations were measured throughout the infusion, and for an 8-hour period after its end. The statistical analysis included 15 patients only, as the catheter had moved into the chest cavity in the other 5. Analgesia was qualified to be adequate by all patients, but there was no statistically significant difference in the amounts of self-administered buprenorphine between groups B and C.(ABSTRACT TRUNCATED AT 250 WORDS)