Table of Contents  
ORIGINAL ARTICLE
Year : 2015  |  Volume : 8  |  Issue : 2  |  Page : 259-264

Post-thoracotomy pain: three different analgesic modalities


Department of Anesthesia and Intensive Care, Faculty of Medicine, Mansoura University, Mansoura, Egypt

Date of Submission05-Dec-2014
Date of Acceptance22-Mar-2015
Date of Web Publication8-May-2015

Correspondence Address:
Ola T Abd el-Dayem
Anesthesia Department, Oncology Center, Mansoura University, Mansoura
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1687-7934.156712

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  Abstract 

Background
Pain following chest surgery is often underestimated and under treated which may lead to pulmonary dysfunction, prolonged stay, higher cost, potential development of chronic pain, and decreased patient satisfaction.
Purpose
The aim of this article is to compare thoracic paravertebral versus epidural thoracic block in the control of post-thoracotomy pain.
Patients and methods
Ninety patients subjected to thoracic surgery were enrolled in this study. They were randomly divided into three equal groups (30 patients each). In the control group (C group) we used intravenous analgesia (fentanyl). In both the thoracic epidural group (TEP group) and the thoracic paravertebral group (TPV group), bupivacaine (0.25%) in a dose of 0.5 mg/kg supplemented with fentanyl 1 μg/kg was used for perioperative analgesia. Assessment included the visual analogue scale for pain, number of patients who needed postoperative analgesia, and the total analgesic dose. Also pulmonary functions represented by forced vital capacity and forced expiratory volume in 1 s were recorded as baseline and at 24 and 48 h postoperatively.
Results
Visual analogue scale for pain was significantly lower in the TPV group compared with the other two groups, and at the same time it was lower in the TEP group compared with the control group. TEP analgesia was associated with significant hypotension compared with the other two groups. The number of patients who needed postoperative analgesia was lower in the TPV group than the other groups. Respiratory functions represented by forced vital capacity and forced expiratory volume in 1 s were better in TEP and TPV groups in comparison with the control group.
Conclusion
Thoracic paravertebral block (TPV) provides a higher quality control of postoperative pain than thoracic epidural (TEP) and systemic opioids.

Keywords: pain after thoracotomy, thoracic epidural, thoracic paravertebral, visual analogue scale


How to cite this article:
Abd el-Dayem OT, Atallah MM, Abdel Fattah MM. Post-thoracotomy pain: three different analgesic modalities. Ain-Shams J Anaesthesiol 2015;8:259-64

How to cite this URL:
Abd el-Dayem OT, Atallah MM, Abdel Fattah MM. Post-thoracotomy pain: three different analgesic modalities. Ain-Shams J Anaesthesiol [serial online] 2015 [cited 2019 Sep 15];8:259-64. Available from: http://www.asja.eg.net/text.asp?2015/8/2/259/156712


  Introduction Top


Unrelieved pain following chest surgery may lead to pulmonary dysfunction, prolonged stay, higher cost, potential development of chronic pain, and decreased patient satisfaction [1] . Epidural and paravertebral blocks (PVBs) have received much attention because they are associated with less sedation and early ambulation. They provide analgesia and greater preservation of lung function [2] .

The thoracic PVB consists of the administration of a local anesthetic solution close to the spinal cord nerve roots after their exit from the intervertebral foramen [3] with vertical diffusion lateral to the vertebral column between the parietal pleura and the end thoracic fascia [4] . It has, for some time, been argued that a thoracic PVB is safer, besides being more effective than an epidural, as a unilateral block may have fewer side effects on circulation and breathing [5] .

The aim of this study was to compare the efficacy of a neuroaxial block represented by thoracic paravertebral and thoracic epidural blocks for management of post-thoracotomy pain to systemic opioids as the control. Moreover, the effects of these techniques on the ventilatory function and hemodynamics were assessed.


  Patients and methods Top


This prospective study included 90 patients subjected to thoracotomy in Mansoura University Hospitals from April 2011 to March 2014. After the approval of the local ethical committee, a written consent was obtained from all patients who participated in the study.

Patients' refusal, local sepsis, pre-existing neurological deficit, and patients with a history of anaphylaxis to local anesthetics, coagulation disorder, or on regular analgesic therapy were excluded from this study.

On the day before surgery all patients were evaluated clinically and all routine investigations were done. They were trained for the use of visual analogue scale (VAS) for pain (0 = no pain and 10 = worst pain imaginable). Basal readings of forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV 1 ) were recorded and oral diazepam 5 mg was administered to all patients. Patients were divided randomly into three equal groups (using the closed envelop method). The control group (C group) which depends on systemic opioids, included 30 patients who received preoperative intravenous fentanyl 3 μg/kg followed by incremental doses (one-fifth the initial dose each) every 60 min till the end of the surgery. The thoracic paravertebral group (TPV group) included 30 patients who received 0.5 mg/kg, 0.25% isobaric bupivacaine. While, the third group, the thoracic epidural group (TEP group) included 30 patients who received the same dose with the same concentration of bupivacaine through the thoracic epidural space. Fentanyl in a dose of 1 μg/kg was added for injection in TEP and TPV groups.

On arrival at the operating room all patients received 2-3 mg intravenous midazolam and they were monitored using peripheral pulse oximetry, five-lead ECG, and a noninvasive blood pressure cuff. A venous line was established using a 16-G intravenous cannula. Also, an arterial line was inserted under local infiltration (2% lidocaine).

In the TPV group, paravertebral blockade was done after placement of the patient in the sitting position with the neck and upper back flexed as much as possible, the block was performed at T6-T8 ipsilateral to the thoracotomy according to the technique described by Eason and Wyatt in 1979 [6] . After sterilization of the back of the patient, local infiltration of the skin with lidocaine 1% was performed at the point of skin puncture which is nearly 3 cm from the anatomical midline. The needle was then advanced at 90° to the skin in all planes to strike the transverse process or the head of the rib at a depth of ~2.5-3.5 cm. Then the needle was walked over the top of the transverse process or the rib. Loss of resistance was used as the needle passed through the costo-transverse ligament. Once the placement of the needle is certain, an epidural catheter (23 G) was advanced through the needle (20 G) 3-5 cm beyond the needle tip. A test dose of 3 ml of 2% lidocaine with 1 : 200 000 adrenaline was injected through the catheter to rule out accidental intrathecal or intravascular placement. Activation of the block was done using a bolus dose of bupivacaine 0.25% in a dose of 0.2 ml/kg with magnesium sulfate 1 mg/kg through the catheter.

In the TEP group, epidural blockade was done after placement of the patient in the sitting position with the neck and upper back flexed as much as possible. The spinous process of T7 was identified at the inferior angle of the scapula and an X mark was drawn on the skin 1-1.5 cm lateral to this spinous process. After sterilization of the back of the patient, local infiltration of the skin and subcutaneous tissues with lidocaine (1%) was performed with a thin needle and the depth of the lamina was identified. The epidural needle (Toughie needle 18 G) with a stylet was advanced into the lamina with the bevel directed cephalically and medially at a 45° angle followed by walking the lamina until the ligament was seated; the epidural space was identified by the loss of resistance technique using saline and a catheter passed 3-4 cm beyond the needle tip. Activation of the epidural block was done using a bolus dose of bupivacaine 0.25% in a dose of 0.2 ml/kg with magnesium sulfate 1 mg/kg through the catheter.

Anesthesia was induced with intravenous propofol 2 mg/kg or until the loss of verbal contact depending on the age. Tracheal intubation was facilitated with intravenous rocuronium 0.8 mg/kg. The control group received intravenous fentanyl 3 μg/kg. Anesthesia was maintained with 1-1.5% isoflurane and incremental doses of rocuronium (fifth initial dose) and ventilation was controlled mechanically and adjusted to maintain the end-tidal carbon dioxide at 30-35 mmHg. At the end of the surgical procedure, the residual neuromuscular block was reversed with neostigmine 0.04 mg/kg and atropine 0.02 mg/kg. Patients received intravenous 30 mg ketorolac, were extubated on the table, and shifted to the postoperative care unit.

Pain scoring was done every 2 h till 24 h postoperatively. As soon as VAS greater than 4 a dose of 5 ml of 0.25% bupivacaine was injected through the catheter into PVB and TEA groups. Patients of the control group received intravenous fentanyl 0.5-1 μg/kg. In any patient of the three studied groups intravenous fentanyl 1 μg/kg was given when VAS was kept higher than 6. FVC and FEV 1 were recorded at 24 and 48 h postoperatively. Number of patients who required postoperative analgesia, the total dose of analgesic used, patient satisfaction, and any side effects were also recorded.

Statistical analysis

The collected data was organized, tabulated, and statistically analyzed using SPSS software (SPSS Inc. Released 2007, SPSS for Windows, Version 16, Chicago, USA). VAS scores of the patients were analyzed using the Mann-Whitney U-test. One way analysis of variance test was done, followed by post-hoc test least significant difference for intergroup's comparisons. For qualitative data, the number and percent distribution was calculated and χ2 -test was used as a test of significance. A P-value less than 0.05 was considered statistically significant. A sample of 30 patients per group was required, with 99% power to detect the differences and a two-sided a error of 0.05.


  Results Top


Patient characteristics and surgical data were comparable in the three study groups ([Table 1]). VAS was significantly lower in the TPV group than the other two groups up to 24 h postoperatively. However VAS was significantly lower in the TEP group than in the C group at 12, 16, and 24 h recorded times ([Table 2]). All patients of the control group (C group) required supplemental postoperative analgesics, compared with only 16 patients in the TEP group and 12 patients in the TPV group. Time of the first postoperative analgesic need was significantly longer in TEP and TPV compared with the C group (P < 0.05). The total amount of analgesic requirements was significantly less in TEP and TPV than in the C group (P < 0.05) ([Table 3]).
Table 1 Demographic data

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Table 2 Visual analogue score of the studied groups in the postoperative period

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Table 3 Number of patients needing postoperative analgesia, time of first analgesic requirement, and total dose of intravenous analgesic used in the postoperative 48 h

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In the postoperative period, there was a statistically significant increase in the FVC ([Table 4]), and in the FEV 1 in both TEP and TPV groups in comparison with the C group ([Table 5]).
Table 4 The preoperative forced vital capacity (FVC 0), FVC 24 h postoperatively (FVC 24), and FVC reading at postoperative 48 h (FVC 48)

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Table 5 The preoperative reading of forced expiratory volume in 1 s (FEV1 0) and FEV1 after postoperative 24 and 48 h

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Intraoperatively, the mean blood pressure was significantly decreased in the TEP group than in the C group throughout the surgery. There was a significant decrease in mean arterial blood pressure in the TEP group compared with the TPV group at the start of surgery, 15, 45, and 120 min from the start of surgery ([Table 6]). Postoperatively, nine patients in the TEP group suffered from hypotension that was treated with intravenous ephedrine in 5-10 mg increments and this was of statistical significance compared with the other two groups. Postoperative vomiting was significantly more in the C group (seven patients) compared with the other two groups. Regarding patients' satisfaction, there was no statistically significant difference between the three studied groups ([Table 7]).
Table 6 Intraoperative mean arterial blood pressure in mmHg between the three groups

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Table 7 Incidence of postoperative vomiting and hypotension intraoperative use of ephedrine and patient satisfaction in the studied groups

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  Discussion Top


Thoracotomy is a severely painful surgical procedure [1],[2] . Moreover pain after thoracic surgery may promote pulmonary complications preventing airways secretions from clearing, in turn, favoring bronchial obstruction, atelectasis, and pneumonia [5] . The nociceptive pathways responsible for post-thoracotomy pain are not completely understood, but the intercostal nerves, the phrenic nerve, and the vagus nerve have all been implicated. The placement and presence of thoracic tubes, rib retraction with or without damage or trapping of the intercostal nerves, and surgical incisions are all causal elements for these inputs [7] .

Several methods for the treatment of post-thoracotomy pain have been proposed with varying success: intercostal block, interpleural analgesia, cryoanalgesia, lumbar epidural, thoracic epidural, PVB, intravenous opiates, NSAIDs, and transcutaneous nerve stimulation [8] . Epidural analgesia has been considered for quite some time to be the gold standard for acute post-thoracotomy pain treatment. However, there are risks associated with the technique such as dural puncture, neurological injury, and paraplegia [9] .

PVB, which was first performed in 1905 to produce abdominal analgesia, is an alternative technique to thoracic epidural analgesia; both being used as methods to control postoperative thoracotomy pain. The administration of a local anesthetic in the paravertebral space achieves a block of the intercostal nerves, their communicating branches, and the corresponding sympathetic chain, which implies a significant sensory and sympathetic block. The extent of the sympathetic block will depend on the volume of anesthetic solution administered [10] .

The summary of outcome of this study revealed that the thoracic epidural (TEP) and thoracic paravertebral (TPV) provide comparable postoperative analgesia superior to systemic opioids (C) following thoracotomy. Incidence of hypotension was evident in the TEP group. Nausea±vomiting was more in the C group. Pulmonary function improved in TEP and TPV groups compared to the C group. Patient's satisfaction is comparable in all studied groups.

In the present study, the preoperative TPV reduced the prevalence and severity of pain as detected by a significantly lower VAS score in the first 24 h and a significant decrease in the number of patients who needed postoperative analgesia compared with TEP or the control group.

This could be explained by the relatively low vascularity of the paravertebral space which limits the local anesthetic diffusion and allows prolonged sensory block and effective postoperative pain relief [11] .

There are contradictory data regarding the analgesic efficacy of TPV as compared with TEP. Two recent meta-analyses concluded that the evidence globally suggests that extrapleural paravertebral analgesia through an indwelling catheter is roughly equivalent to that of thoracic epidural analgesia. One of the limitations of the meta-analyses of these studies, however, is the variability of the techniques used, thus leading the authors of both reviews to suggest that further prospective trials are required to adequately address the issue [12],[13] . In contrast, Richardson and colleagues reported superior analgesia with continuous paravertebral infusion (CPI) of 0.5% bupivacaine compared with continuous TEA with 0.25% bupivacaine. In addition, these authors suggested that there are fewer postoperative complications with CPI. One limitation pointed out by the authors in the Richardson study is the fact that more concentrated bupivacaine was used in the CPI compared with the TEA [14] . Although the data appear to suggest that epidural and paravertebral modalities with local anesthetic only provide comparable analgesia, the findings of the Richardson study suggested that further investigation may be warranted and that local anesthetic concentration may play a role. This study examined this issue using a direct comparison of the techniques with equivalent local anesthetic concentrations.

The incidence of vomiting in patients in PVB and TEA was less pronounced than those patients in the C group. This is in accordance with previous studies [15],[16] . This may be explained by the fact that in the PVB and TEA patients, we administered no opioids and continuous infusion of bupivacaine was used for analgesia.

In this study, the PVB was associated with less hemodynamic changes than the thoracic epidural as demonstrated by the incidence of hypotension. In agreement with these results, Kumar and Rajendran [17] reported that hypotension was more common with the thoracic epidural than the PVB. They explained that due to the bilateral sympathetic block which occurs with the thoracic epidural and leads to peripheral vasodilatation, decrease in total peripheral resistance and hence a decrease in blood pressure results. Richardson and colleagues compared thoracic epidural analgesia and thoracic PVBs following thoracotomies, and found that the efficacy of the two methods was similar.

However, the incidence of secondary effects in the form of nausea, vomiting, hypotension, and urine retention was higher in the epidural group [14] .

Mean heart rate and blood pressure were significantly increased in the C group than the two regional techniques at the start of surgery, because the regional blockade could better suppress the stress response than the systemic application of intravenous analgesics [18],[19] . Hypotension was mild (less than 30% of the preoperative value) in PVB and control groups. On the other hand, hypotension was severe in 11 patients (33.3%) of the TEA group that needed ephedrine for its correction.

As regards pulmonary functions, our results showed that the PVB and the epidural block are comparable in terms of analgesic quality, although the PVB is associated with a lower incidence of pulmonary complications. A systematic review and meta-analysis of randomized studies was recently published comparing the analgesic efficacy of PVBs and thoracic epidurals for thoracotomies.

The results showed an absence of significant differences with respect to the quality of the analgesic used at all time periods of observation. However, they did observe a significant reduction in the incidence of pulmonary complications, defined as the presence of pneumonia or atelectasis, in the group that received thoracic PVBs (odds ratio 0.36; 95% confidence interval 0.14-0.92). Respiratory function, which was evaluated as the percent change in peak flow, or FEV 1 , also improved significantly in the paravertebral group with respect to the epidural group at 24 h postoperation. The improvement was attributed to the unilateral nature of the block in the case of PVBs, as opposed to the bilateral nature of the epidural, given that respiratory mechanics are better preserved in the first case [13] .


  Conclusion Top


The thoracic PVB (TPV) provides a higher quality control of postoperative pain than the thoracic epidural (TEP) and systemic opioids. The technical simplicity, efficacy, few side effects, high tolerance level, and few contraindications of TPV could project it as the method of choice for this type of surgery.


  Acknowledgements Top


Conflicts of interest

None declared.



 
  References Top

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Joshi GP, Bonnet F, Shah R, et al. A systematic review of randomized trials evaluating regional techniques for post- thoracotomy analgesia. Anesth Analg 2008; 107:1026-1040.  Back to cited text no. 12
    
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Davies RG, Myles PS, Graham JM. A comparison of the analgesic efficacy and side-effects of paravertebral vs epidural blockade for thoracotomy - a systematic eview and meta-analysis of randomized trials. Br J Anaesth 2006; 96:418-426.  Back to cited text no. 13
    
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Richardson J, Sabanathan S, Jones J, Shah RD, Cheema S, Mearns AJ. A prospective, randomized comparison of preoperative and continuous balanced epidural or paravertebral bupivacaine on post-thoracotomy pain, pulmonary function and stress responses. Br J Anaesth 1999; 83:387-392.  Back to cited text no. 14
    
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Kumar TS, Rajendran R. Comparative evaluation of thoracic epidural versus thoracic para vertebral block for post thoracotomy pain relief with 0.25% bupivacaine. ndian J Anesth 2003; 47:269-274.  Back to cited text no. 17
    
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]



 

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