Original Thoracic
Comparison of Transcutaneous Electrical Nerve Stimulation and Paravertebral Block for Postthoracotomy Pain Relief Elif Dogan Baki1 Gürhan Öz2 Serdar Kokulu1 Hasan Şenay1 Gökcen Doğan2
Alper Murat Ulaşlı3
1 Department of Anesthesiology and Reanimation, Faculty of
Medicine, Afyon Kocatepe University, Afyon, Turkey 2 Department of Thoracic Surgery, Faculty of Medicine, Afyon Kocatepe University, Afyon, Turkey 3 Department of Physical Medicine and Rehabilitation, Faculty of Medicine, Afyon Kocatepe University, Afyon, Turkey
Yüksel Ela1
Remziye Gul Sıvacı1
Address for correspondence Assistant Professor Elif Dogan Baki, Department of Anestheisology and Reanimation, Faculty of Medicine, Afyon Kocatepe University, Ali Cetinkaya Kampusu, Afyon-İzmir Karayolu 8 km, Afyon 03200, Turkey (e-mail: [email protected]).
Thorac Cardiovasc Surg 2015;63:514–518.
Abstract
Keywords
► analgesia ► thoracotomy ► paravertebral
Background Inadequate relief of postthoracotomy pain is a major reason of increased occurrence of postoperative complications. We aimed to investigate and compare the effects of transcutaneous electrical nerve stimulation (TENS) and paravertebral block (PVB) to relieve pain after thoracotomy procedures. Materials and Methods We studied 40 patients who underwent thoracotomy. Patients were randomly allocated to receive either PVB (group P, n ¼ 20) or TENS (group T, n ¼ 20) for postoperative pain. The electrodes of TENS were placed 2 cm under and 2 cm over the thoracotomy cut on both posterior and anterior sides. The surgeon inserted paravertebral catheters using direct vision at the end of the surgery. A patient-controlled analgesia (PCA) device was connected to all patients. Visual analog scales, patient demand, and consumption of tramadol were evaluated postoperatively. Results Mean visual analog scale (VAS) values were significantly lower in group P for all time points. The patients in group P needed lower amounts of opioid (tramadol) and the difference was statistically significant (258.4 13.52 mg vs. 314.4 8.65 mg, p ¼ 0.005). In addition, the number of demand attempts recorded from the PCA device was significantly lower in group P (14.95 13.64 vs. 26.7 17.34, respectively and p < 0.001). Conclusion TENS has beneficial effects for pain relief after thoracotomy, without any side effects; however, it cannot provide sufficient pain relief when compared with PVB.
Introduction A thoracotomy is reported to be one of the most painful surgical techniques.1 Different analgesic methods, such as, intercostal, paravertebral, interpleural, and epidural blocks, have been used to provide relieving pain after thoracotomy.2 Because postthoracotomy pain is completely unilateral and is usually associated with pain caused directly by the thoracotomy, a more peripheral and specific nerve block such as a
received July 11, 2014 accepted after revision November 28, 2014 published online February 16, 2015
paravertebral blockade can be used effectively for postoperative analgesia.3 This produces excellent results with a lower incidence of complications, including hypotension, urinary retention, respiratory problems, and postoperative nausea and vomiting.4,5 Sometimes it has been claimed that a paravertebral block (PVB) may give a similar level of analgesia as thoracic epidural analgesia.5 TENS is a noninvasive, widely accessible, and low-cost modality for pain control without any serious complications.
© 2015 Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0035-1544212. ISSN 0171-6425.
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514
TENS is also quite easy to perform and has been used to reduce postoperative pain related to several procedures, such as cardiac operations and thoracotomy,6 but its effects are controversial. The application of TENS has been demonstrated to reduce opioid and nonopioid analgesic intake after cardiothoracic surgeries and has helped obtain adequate pain control.7,8 These studies used TENS in addition to pharmacologic analgesia and compared this with placebo, or compared two different TENS application methods. The analgesic performance of TENS in addition to pharmacologic analgesia—to the best of our knowledge—has never been compared with an invasive technique performed in addition to pharmacologic analgesia after thoracotomy. Therefore, we aimed to investigate TENS as a means of adjunctive therapy in postthoracotomy pain control and compare it with thoracal PVB, an invasive and well-accepted analgesic method.
Materials and Methods The ethics committee of the Afyon Kocatepe University confirmed the study protocol on the 28th June 2012 with the number 131. Written informed consent was obtained from 40 patients undergoing elective thoracotomy. Before the surgery, patients were randomly assigned to get either PVB or TENS for the treatment of pain postoperatively using a sealed envelope system. Patients with cardiac disease, hepatic disease, renal failure, cardiac arrhythmia, coagulation disorders, allergy to local anesthetics or those fitted with a pacemaker, or with cerebral confusion were excluded. The visual analog scale (VAS) and the patient-controlled analgesia (PCA) device were clarified to all patients during preoperative visit. Patients in both groups received midazolam before surgical procedures. Anesthesia was induced by propofol 2 mg/kg, 1 mg/kg lidocaine, 2 µg/kg fentanyl, and tracheal intubation was facilitated with rocuronium 0.5 to 0.6 mg/kg. Maintenance of anesthesia was provided with 50% air and 1 to 2% sevoflurane in oxygen. Patients were given 100% oxygen during one-lung ventilation (OLV). Oxygen saturation, electrocardiogram, end-tidal carbon dioxide, invasive blood pressure, and central venous pressure were monitored throughout the surgery. Patient groups were assigned in the following way: Group T: Conventional TENS was used postoperatively for 24 hours continuously. The TENS system (System 2000, Biomedical Life Systems, Vista, California, United States) had two channels and four electrodes. It was run at 100-Hz frequency, voltage intervals of 100 milliseconds, and amplitude adjusted to such a way that it would not bother the patient and would be below the motor unit. The TENS electrodes were placed 2 cm under and 2 cm over the thoracotomy incision on both the anterior and posterior sides. Group P: PVB group; at the end of the surgery, the surgeon inserted paravertebral catheters using direct vision. A 16G Touhy needle was inserted at a distance of 5 cm from midline below incision interspace and the needle was advanced slowly until the tip bulged into potential space, which is called the paravertebral space, beneath the parietal pleura. The epidural catheter was passed through the needle and inserted inside the thoracic
Baki et al.
cavity. An extrapleural pocket of 4 to 5 cm was created using a curved clamp inserting below the parietal pleura. The catheter was placed below the parietal pleura and carefully taped in place. A loading dose of 10 mL of 0.5% bupivacaine was given. The catheter was then fitted to an epidural infusion pump and an infusion of local anesthetic þ opioid mixture (bupivacaine 0.5% þ 10 mL fentanyl þ 110 mL SF) was begun. We usually began at a rate of 5 to 10 mL/min (0.1 mL/kg/h), depending on the patient’s size, age, and performance status. After 24 hours postoperatively, the concentration of bupivacaine was decreased to 0.25%. At the end of the surgery, 1 g paracetamol and 1 mg/kg tramadol were given to all patients, and tramadol PCA (400 mg tramadol [8 mL] þ saline [92 cc]) with 10 mg continuous, 20-mg demand dose and 30-minute lockout time was set for all patients in recovery room and maintained throughout the postoperative period. The total and demand doses of tramadol and the given number of demands were recorded from the PCA device’ history 24 hours after the procedure. Supplementary doses given to patients were also recorded. In the intensive care unit (ICU), oxygen (2 L/min) with a nasal mask was given to all patients for 12 hours postoperatively. By an anesthesiologist, 10-cm VAS (0 ¼ no pain, 10 ¼ maximal pain) was used for the assessment of pain at the 2nd, 4th, 6th, 12th, and 24th hours in ICU at rest and during coughing. Routine use of intravenous paracetamol four times a day (intravenous infusion) and nonsteroidal anti-inflammatory drugs twice a day (intramuscular) were given for the rescue treatment when the VAS score was over 4 at rest and 6 during coughing in both groups. If their analgesia was adequate, rescue analgesics would not be given at their routine given times. When the patient noticed strong pain despite these treatments, intravenous infusion of meperidine 50 mg was given. Demographic data of the patients, such as age, sex, body mass index, and extent of surgical resection (e.g., lobectomy, cystectomy, wedge resection) were recorded. Spirometric measurements of respiratory functions, including forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity (FEV1/FVC) were noted preoperatively and at the fifth day postoperatively. Hemodynamic parameters including mean arterial pressures (MAP), heart rate (HR), and saturation of oxygen were noted during the first 24 hours and the 1st, 4th, 6th, 12th, and 24th hours postoperatively.
Statistics Analysis of statistics was done using IBM SPSS Statistics version 20. Data were expressed as mean SD. MannWhitney U test was used for comparing continuous variables and chi-square test was used for comparing categorical variables. Wilcoxon signed rank test was used for comparing pre- and postoperative variables. A p-value less than 0.05 was considered to show a statistically significant difference.
Results Forty patients with ASA physical status between I and III undergoing thoracotomy completed the study. Patient and Thoracic and Cardiovascular Surgeon
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No. 6/2015
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Comparison of TENS and PVB for Postthoracotomy Pain Relief
Comparison of TENS and PVB for Postthoracotomy Pain Relief
Baki et al.
Table 1 Demographic data and operation characteristics Group T (n ¼ 20)
Group P (n ¼ 20)
p
Sex (female/male), n
6/14
9/11
0.327a
Age (y)
50.05 13.34
53.85 18.90
0.279b
Height (cm)
69.25 7.29
72.15 8.80
0.122b
Weight (kg)
169.75 6.99
169.15 7.78
0.719b
Duration of operation (min)
197 59.12
175.75 47.79
0.201b
Duration of OLV (min)
113 39.88
108.50 37.03
0.660b
Lobectomy
7
8
0.772
Cystectomy
9
8
Wedge resection
2
3
Pneumonectomy
2
1
Surgical procedure
Abbreviations: Group P, group paravertebral; group T, group TENS; OLV, one-lung ventilation. Note: Data expressed as mean SD. a Data expressed as Chi-square test. b Data expressed as Mann–Whitney U-test.
operation characteristics were shown in ►Table 1. No significant differences were found between the groups regarding age, sex, weight, height of the patients, duration of the operation, duration of OLV, or type of surgical procedure (►Table 1). The variations of the VAS for pain at rest and during coughing between the groups at the first day of the postoperative period are shown in ►Figs. 1 and 2, respectively. Mean VAS values were significantly lower in group P at all time points assessed, both at rest and while coughing. Group P patients required less opioid than group T patients and the difference was statistically significant (258.4 13.52 mg vs. 314.4 8.65 mg, p ¼ 0.005). Furthermore, the number of demand attempts recorded from the PCA device was significantly lower in group P (14.95 13.64 vs. 26.7 17.34, respectively, and p < 0.001). All the patients in group T needed an additional dose of analgesics postoperatively; however, 15 of 20 patients needed additional analgesics in
Fig. 1 Comparison of visual analog scale (VAS) during rest between groups at 2nd, 4th, 6th, 12th, and 24th hours (p < 0.01 at 2nd, 4th, 6th, 12th, and p < 0.05 at 24th hour). Thoracic and Cardiovascular Surgeon
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group P. Meperidine was not used as an additional analgesic in both groups. FEV1 and FEV1/FVC values measured on the preoperative day and at the postoperative fifth day are shown in ►Table 2. Preoperatively, FEV1 and FEV1/FVC values were similar in both groups (p ¼ 0.612 and p ¼ 0.270, respectively). Group P experienced a nonsignificant decrease in FEV1 (p ¼ 0.147) but a significant increase in FEV1/FVC (p ¼ 0.001). However, in group T the decrease in FEV1 and increase in FEV1/FVC were both statistically significant (p < 0.001). At the postoperative fifth day, though the mean FEV1 value was nonsignificantly higher in group P, FEV1/FVC was significantly higher in group T (p ¼ 0.124, and p ¼ 0.017, respectively). Hemodynamic parameters of MAP and HR were lower in group P, but the differences were not significant (p > 0.05 for all) (►Figs. 3 and 4).
Discussion Poor pain control after thoracotomy operations may manifest with patient being unable to take adequate breaths and to cough forcibly, and finally this leads to retained secretions, atelectasis, hypoxemia, and infection.5 This emphasizes the importance of postthoracotomy analgesia. Paravertebral nerve block is a frequently used invasive method of postthoracotomy analgesia, though TENS offers some advantages, such as being noninvasive, nonaddictive, portable, and simple to use, and has been shown to reduce postoperative analgesic consumption.9 To the best of our knowledge, no study in the literature compares the effectiveness of these two treatment modalities for postoperative pain relief. The main findings of the current study include the following: (1) Patients who received PVB experienced less pain both at rest and while coughing and needed less opioid analgesic; (2) hemodynamic parameters did not differ among groups; however, FEV1/FVC
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Fig. 2 Comparison between the groups of visual analog scale (VAS) when coughing. p< 0.001 at all time points.
was significantly higher in patients who received TENS postoperatively. Erdogan et al10 investigated the TENS efficacy on postthoracotomy pain and respiratory function. The authors reported that patients for whom TENS was used in addition to intercostal nerve blockade had greater improvement in pulmonary function with less opioid requirements. Their VAS scores were less than 3 at rest and less than 5 when coughing at the 6 hour postoperatively. In our study, VAS scores were between 6 and 3 when coughing and between 5 and 2 at rest in the TENS group, whereas they were between 5 and 2 when coughing and between 3 and 1 at rest in group P after 6 hours postoperatively. Intercostal nerve blockage was used in both groups (control and TENS) intraoperatively. Perhaps this could explain the lower pain scores of patients in the early postoperative period. We used additional analgesics in both groups when VAS scores were more than 3. All the patients in group T needed an additional dose of analgesics postoperatively; however, 15 of 20 patients needed additional analgesic in group P. Unfortunately, we did not record how much and at what time this was given, which is one of the limitation of our study. The other limitations were that although we continued the analgesic treatments of TENS and paravertebral infusion (gradually decreased the concentration of local anesthetics) for 4 days, we recorded data only for the first 24 hours and also we did not mention complications related to pain, such as atelectasis in this study. We did not notice any side effect or intolerance except for minimal, unimportant discomfort due to TENS treatment in accordance with previous studies.10,11 Hemodynamic parameters were not significantly different between the groups.
Baki et al.
Declined functional residual capacity and the vital capacity values were found after thoracotomy procedures and pain has been shown as a major contributing factor.12 In a metaanalysis of trials assessing the pulmonary function following thoracic surgery, the most effective analgesic method for preservation of spirometric function was PVB.13 Our spirometric values recorded on the fifth day postoperatively were higher than the preoperative values and this increase was significant in the TENS group. Also, we found that PVB reduced postoperative pain and opioid requirements, but TENS was not as effective as PVB against severe postoperative pain. Likewise, Benedetti and collegues14 showed that TENS is effective in relieving mild or moderate acute postthoracotomy pain associated with muscle-sparing thoracotomy, median sternotomy, and video-assisted thoracoscopic surgery. PVBs are performed using several approaches, varying from a percutaneous needle below or above the transverse vertebral process for single shot or prolonged catheter infusion to visually guided placement of a catheter during surgery. Richardson et al15 compared epidural and paravertebral bupivacaine on postthoracotomy pain, respiratory function, and stress responses. Lower morphine consumptions and VAS values were reported in paravertebral group in their study. Continuous PVB has also been demonstrated to provide excellent postoperative analgesia when compared with single-shot paravertebral or intrapleural blocks after thoracotomy.16 In the study by Perttunen et al,17 extradural, paravertebral and intercostal blocks for postthoracotomy pain were compared; similar levels of pain, opioid consumptions, and respiratory function were noted in the three groups. PVB technique can be inserted under direct vision of the surgeon before the end of surgical procedures, it does not delay surgery as thoracal epidural block does, and saves precious time in the operating room. In the current study paravertebral catheters were placed by the surgeon at the end of the operation. The amount and concentration of local anesthetics performed in neuraxial blocks vary depending on the physician and institute. Because we did not have the chance to monitor local anesthetics plasma levels, we chose using the management of the amount in the literature.15 Meissner mentioned the use of TENS and acupuncture in his review, and found that the number of new high-quality studies on acupuncture and TENS in postoperative pain is restricted. As these techniques obviously do no harm, their use as adjunctive pain treatment approaches should be considered if conventional techniques fail.18 In our study,
Table 2 Pre- and postoperative 5th day FEV1 and FEV1/FVC values of treatment groups
FEV1 FEV1/FVC
Preoperative
Postoperative 5th day
Group P
2.94 0.86
2.81 0.69
Group T
3.07 0.78
2.52 0.9
Group P
75.31 8.65
79.45 9.38
Group T
79.3 7.32
85.9 6.78
Abbreviations: FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity. Note: Data expressed as mean SD, FEV1, and FEV1/FVC. Thoracic and Cardiovascular Surgeon
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Comparison of TENS and PVB for Postthoracotomy Pain Relief
Comparison of TENS and PVB for Postthoracotomy Pain Relief
4
5
6
Fig. 3 Mean arterial pressure (mm Hg). No significant differences between the groups regarding mean arterial pressure measured on the 1st, 4th, 8th, 12th, and 24th hours after the operation (p > 0.05).
7
8
9
10
11
Fig. 4 Heart rates of the groups. No significant differences were measured on the 1st, 4th, 8th, 12th, or 24th hours after the operation (p > 0.05).
TENS has beneficial effects for pain relief after thoracotomy without any side effects; however, it cannot provide sufficient pain relief when compared with PVB. Conflict of Interest None declared.
12
13
14
15
References
16
1 Tiippana E, Nilsson E, Kalso E. Post-thoracotomy pain after thoracic
epidural analgesia: a prospective follow-up study. Acta Anaesthesiol Scand 2003;47(4):433–438 2 Yegin A, Erdogan A, Kayacan N, Karslı B. Early postoperative pain management after thoracic surgery; pre- and postoperative versus postoperative epidural analgesia: a randomised study. Eur J Cardiothorac Surg 2003;24(3):420–424 3 Casati A, Alessandrini P, Nuzzi M, et al. A prospective, randomized, blinded comparison between continuous thoracic paravertebral
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18
Baki et al. and epidural infusion of 0.2% ropivacaine after lung resection surgery. Eur J Anaesthesiol 2006;23(12):999–1004 Kaiser AM, Zollinger A, De Lorenzi D, Largiadèr F, Weder W. Prospective, randomized comparison of extrapleural versus epidural analgesia for postthoracotomy pain. Ann Thorac Surg 1998; 66(2):367–372 Powell ES, Cook D, Pearce AC, et al; UKPOS Investigators. A prospective, multicentre, observational cohort study of analgesia and outcome after pneumonectomy. Br J Anaesth 2011;106(3): 364–370 Carrol EN, Badura AS. Focal intense brief transcutaneous electric nerve stimulation for treatment of radicular and postthoracotomy pain. Arch Phys Med Rehabil 2001;82(2):262–264 Solak O, Emmiler M, Ela Y, et al. Comparison of continuous and intermittent transcutaneous electrical nerve stimulation in postoperative pain management after coronary artery bypass grafting: a randomized, placebo-controlled prospective study. Heart Surg Forum 2009;12(5):E266–E271 Solak O, Turna A, Pekçolaklar A, et al. Transcutaneous electric nerve stimulation for the treatment of postthoracotomy pain: a randomized prospective study. Thorac Cardiovasc Surg 2007; 55(3):182–185 Bjordal JM, Johnson MI, Ljunggreen AE. Transcutaneous electrical nerve stimulation (TENS) can reduce postoperative analgesic consumption. A meta-analysis with assessment of optimal treatment parameters for postoperative pain. Eur J Pain 2003;7(2): 181–188 Erdogan M, Erdogan A, Erbil N, Karakaya HK, Demircan A. Prospective, Randomized, Placebo-controlled Study of the Effect of TENS on postthoracotomy pain and pulmonary function. World J Surg 2005;29(12):1563–1570 Naaman SC, Stein RB, Thomas C. Minimizing discomfort with surface neuromuscular stimulation. Neurorehabil Neural Repair 2000;14(3):223–228 Daly DJ, Myles PS. Update on the role of paravertebral blocks for thoracic surgery: are they worth it? Curr Opin Anaesthesiol 2009; 22(1):38–43 Richardson J, Sabanathan S, Shah R. Post-thoracotomy spirometric lung function: the effect of analgesia. A review. J Cardiovasc Surg (Torino) 1999;40(3):445–456 Benedetti F, Amanzio M, Casadio C, et al. Control of postoperative pain by transcutaneous electrical nerve stimulation after thoracic operations. Ann Thorac Surg 1997;63(3):773–776 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 postthoracotomy pain, pulmonary function and stress responses. Br J Anaesth 1999;83(3):387–392 Richardson J, Sabanathan S, Mearns AJ, Shah RD, Goulden C. A prospective, randomized comparison of interpleural and paravertebral analgesia in thoracic surgery. Br J Anaesth 1995;75(4): 405–408 Perttunen K, Nilsson E, Heinonen J, Hirvisalo EL, Salo JA, Kalso E. Extradural, paravertebral and intercostal nerve blocks for postthoracotomy pain. Br J Anaesth 1995;75(5):541–547 Winfried Meissner. The role of acupuncture and transcutaneouselectrical nerve stimulation for postoperative pain control. Curr Opin Anaesthesiol 2000;22:623–626
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Comparison of Transcutaneous Electrical Nerve Stimulation and Paravertebral Block for Postthoracotomy Pain Relief Elif Dogan Baki1 Gürhan Öz2 Serdar Kokulu1 Hasan Şenay1 Gökcen Doğan2
Alper Murat Ulaşlı3
1 Department of Anesthesiology and Reanimation, Faculty of
Medicine, Afyon Kocatepe University, Afyon, Turkey 2 Department of Thoracic Surgery, Faculty of Medicine, Afyon Kocatepe University, Afyon, Turkey 3 Department of Physical Medicine and Rehabilitation, Faculty of Medicine, Afyon Kocatepe University, Afyon, Turkey
Yüksel Ela1
Remziye Gul Sıvacı1
Address for correspondence Assistant Professor Elif Dogan Baki, Department of Anestheisology and Reanimation, Faculty of Medicine, Afyon Kocatepe University, Ali Cetinkaya Kampusu, Afyon-İzmir Karayolu 8 km, Afyon 03200, Turkey (e-mail: [email protected]).
Thorac Cardiovasc Surg 2015;63:514–518.
Abstract
Keywords
► analgesia ► thoracotomy ► paravertebral
Background Inadequate relief of postthoracotomy pain is a major reason of increased occurrence of postoperative complications. We aimed to investigate and compare the effects of transcutaneous electrical nerve stimulation (TENS) and paravertebral block (PVB) to relieve pain after thoracotomy procedures. Materials and Methods We studied 40 patients who underwent thoracotomy. Patients were randomly allocated to receive either PVB (group P, n ¼ 20) or TENS (group T, n ¼ 20) for postoperative pain. The electrodes of TENS were placed 2 cm under and 2 cm over the thoracotomy cut on both posterior and anterior sides. The surgeon inserted paravertebral catheters using direct vision at the end of the surgery. A patient-controlled analgesia (PCA) device was connected to all patients. Visual analog scales, patient demand, and consumption of tramadol were evaluated postoperatively. Results Mean visual analog scale (VAS) values were significantly lower in group P for all time points. The patients in group P needed lower amounts of opioid (tramadol) and the difference was statistically significant (258.4 13.52 mg vs. 314.4 8.65 mg, p ¼ 0.005). In addition, the number of demand attempts recorded from the PCA device was significantly lower in group P (14.95 13.64 vs. 26.7 17.34, respectively and p < 0.001). Conclusion TENS has beneficial effects for pain relief after thoracotomy, without any side effects; however, it cannot provide sufficient pain relief when compared with PVB.
Introduction A thoracotomy is reported to be one of the most painful surgical techniques.1 Different analgesic methods, such as, intercostal, paravertebral, interpleural, and epidural blocks, have been used to provide relieving pain after thoracotomy.2 Because postthoracotomy pain is completely unilateral and is usually associated with pain caused directly by the thoracotomy, a more peripheral and specific nerve block such as a
received July 11, 2014 accepted after revision November 28, 2014 published online February 16, 2015
paravertebral blockade can be used effectively for postoperative analgesia.3 This produces excellent results with a lower incidence of complications, including hypotension, urinary retention, respiratory problems, and postoperative nausea and vomiting.4,5 Sometimes it has been claimed that a paravertebral block (PVB) may give a similar level of analgesia as thoracic epidural analgesia.5 TENS is a noninvasive, widely accessible, and low-cost modality for pain control without any serious complications.
© 2015 Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0035-1544212. ISSN 0171-6425.
Downloaded by: University of Iowa Libraries. Copyrighted material.
514
TENS is also quite easy to perform and has been used to reduce postoperative pain related to several procedures, such as cardiac operations and thoracotomy,6 but its effects are controversial. The application of TENS has been demonstrated to reduce opioid and nonopioid analgesic intake after cardiothoracic surgeries and has helped obtain adequate pain control.7,8 These studies used TENS in addition to pharmacologic analgesia and compared this with placebo, or compared two different TENS application methods. The analgesic performance of TENS in addition to pharmacologic analgesia—to the best of our knowledge—has never been compared with an invasive technique performed in addition to pharmacologic analgesia after thoracotomy. Therefore, we aimed to investigate TENS as a means of adjunctive therapy in postthoracotomy pain control and compare it with thoracal PVB, an invasive and well-accepted analgesic method.
Materials and Methods The ethics committee of the Afyon Kocatepe University confirmed the study protocol on the 28th June 2012 with the number 131. Written informed consent was obtained from 40 patients undergoing elective thoracotomy. Before the surgery, patients were randomly assigned to get either PVB or TENS for the treatment of pain postoperatively using a sealed envelope system. Patients with cardiac disease, hepatic disease, renal failure, cardiac arrhythmia, coagulation disorders, allergy to local anesthetics or those fitted with a pacemaker, or with cerebral confusion were excluded. The visual analog scale (VAS) and the patient-controlled analgesia (PCA) device were clarified to all patients during preoperative visit. Patients in both groups received midazolam before surgical procedures. Anesthesia was induced by propofol 2 mg/kg, 1 mg/kg lidocaine, 2 µg/kg fentanyl, and tracheal intubation was facilitated with rocuronium 0.5 to 0.6 mg/kg. Maintenance of anesthesia was provided with 50% air and 1 to 2% sevoflurane in oxygen. Patients were given 100% oxygen during one-lung ventilation (OLV). Oxygen saturation, electrocardiogram, end-tidal carbon dioxide, invasive blood pressure, and central venous pressure were monitored throughout the surgery. Patient groups were assigned in the following way: Group T: Conventional TENS was used postoperatively for 24 hours continuously. The TENS system (System 2000, Biomedical Life Systems, Vista, California, United States) had two channels and four electrodes. It was run at 100-Hz frequency, voltage intervals of 100 milliseconds, and amplitude adjusted to such a way that it would not bother the patient and would be below the motor unit. The TENS electrodes were placed 2 cm under and 2 cm over the thoracotomy incision on both the anterior and posterior sides. Group P: PVB group; at the end of the surgery, the surgeon inserted paravertebral catheters using direct vision. A 16G Touhy needle was inserted at a distance of 5 cm from midline below incision interspace and the needle was advanced slowly until the tip bulged into potential space, which is called the paravertebral space, beneath the parietal pleura. The epidural catheter was passed through the needle and inserted inside the thoracic
Baki et al.
cavity. An extrapleural pocket of 4 to 5 cm was created using a curved clamp inserting below the parietal pleura. The catheter was placed below the parietal pleura and carefully taped in place. A loading dose of 10 mL of 0.5% bupivacaine was given. The catheter was then fitted to an epidural infusion pump and an infusion of local anesthetic þ opioid mixture (bupivacaine 0.5% þ 10 mL fentanyl þ 110 mL SF) was begun. We usually began at a rate of 5 to 10 mL/min (0.1 mL/kg/h), depending on the patient’s size, age, and performance status. After 24 hours postoperatively, the concentration of bupivacaine was decreased to 0.25%. At the end of the surgery, 1 g paracetamol and 1 mg/kg tramadol were given to all patients, and tramadol PCA (400 mg tramadol [8 mL] þ saline [92 cc]) with 10 mg continuous, 20-mg demand dose and 30-minute lockout time was set for all patients in recovery room and maintained throughout the postoperative period. The total and demand doses of tramadol and the given number of demands were recorded from the PCA device’ history 24 hours after the procedure. Supplementary doses given to patients were also recorded. In the intensive care unit (ICU), oxygen (2 L/min) with a nasal mask was given to all patients for 12 hours postoperatively. By an anesthesiologist, 10-cm VAS (0 ¼ no pain, 10 ¼ maximal pain) was used for the assessment of pain at the 2nd, 4th, 6th, 12th, and 24th hours in ICU at rest and during coughing. Routine use of intravenous paracetamol four times a day (intravenous infusion) and nonsteroidal anti-inflammatory drugs twice a day (intramuscular) were given for the rescue treatment when the VAS score was over 4 at rest and 6 during coughing in both groups. If their analgesia was adequate, rescue analgesics would not be given at their routine given times. When the patient noticed strong pain despite these treatments, intravenous infusion of meperidine 50 mg was given. Demographic data of the patients, such as age, sex, body mass index, and extent of surgical resection (e.g., lobectomy, cystectomy, wedge resection) were recorded. Spirometric measurements of respiratory functions, including forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity (FEV1/FVC) were noted preoperatively and at the fifth day postoperatively. Hemodynamic parameters including mean arterial pressures (MAP), heart rate (HR), and saturation of oxygen were noted during the first 24 hours and the 1st, 4th, 6th, 12th, and 24th hours postoperatively.
Statistics Analysis of statistics was done using IBM SPSS Statistics version 20. Data were expressed as mean SD. MannWhitney U test was used for comparing continuous variables and chi-square test was used for comparing categorical variables. Wilcoxon signed rank test was used for comparing pre- and postoperative variables. A p-value less than 0.05 was considered to show a statistically significant difference.
Results Forty patients with ASA physical status between I and III undergoing thoracotomy completed the study. Patient and Thoracic and Cardiovascular Surgeon
Vol. 63
No. 6/2015
515
Downloaded by: University of Iowa Libraries. Copyrighted material.
Comparison of TENS and PVB for Postthoracotomy Pain Relief
Comparison of TENS and PVB for Postthoracotomy Pain Relief
Baki et al.
Table 1 Demographic data and operation characteristics Group T (n ¼ 20)
Group P (n ¼ 20)
p
Sex (female/male), n
6/14
9/11
0.327a
Age (y)
50.05 13.34
53.85 18.90
0.279b
Height (cm)
69.25 7.29
72.15 8.80
0.122b
Weight (kg)
169.75 6.99
169.15 7.78
0.719b
Duration of operation (min)
197 59.12
175.75 47.79
0.201b
Duration of OLV (min)
113 39.88
108.50 37.03
0.660b
Lobectomy
7
8
0.772
Cystectomy
9
8
Wedge resection
2
3
Pneumonectomy
2
1
Surgical procedure
Abbreviations: Group P, group paravertebral; group T, group TENS; OLV, one-lung ventilation. Note: Data expressed as mean SD. a Data expressed as Chi-square test. b Data expressed as Mann–Whitney U-test.
operation characteristics were shown in ►Table 1. No significant differences were found between the groups regarding age, sex, weight, height of the patients, duration of the operation, duration of OLV, or type of surgical procedure (►Table 1). The variations of the VAS for pain at rest and during coughing between the groups at the first day of the postoperative period are shown in ►Figs. 1 and 2, respectively. Mean VAS values were significantly lower in group P at all time points assessed, both at rest and while coughing. Group P patients required less opioid than group T patients and the difference was statistically significant (258.4 13.52 mg vs. 314.4 8.65 mg, p ¼ 0.005). Furthermore, the number of demand attempts recorded from the PCA device was significantly lower in group P (14.95 13.64 vs. 26.7 17.34, respectively, and p < 0.001). All the patients in group T needed an additional dose of analgesics postoperatively; however, 15 of 20 patients needed additional analgesics in
Fig. 1 Comparison of visual analog scale (VAS) during rest between groups at 2nd, 4th, 6th, 12th, and 24th hours (p < 0.01 at 2nd, 4th, 6th, 12th, and p < 0.05 at 24th hour). Thoracic and Cardiovascular Surgeon
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group P. Meperidine was not used as an additional analgesic in both groups. FEV1 and FEV1/FVC values measured on the preoperative day and at the postoperative fifth day are shown in ►Table 2. Preoperatively, FEV1 and FEV1/FVC values were similar in both groups (p ¼ 0.612 and p ¼ 0.270, respectively). Group P experienced a nonsignificant decrease in FEV1 (p ¼ 0.147) but a significant increase in FEV1/FVC (p ¼ 0.001). However, in group T the decrease in FEV1 and increase in FEV1/FVC were both statistically significant (p < 0.001). At the postoperative fifth day, though the mean FEV1 value was nonsignificantly higher in group P, FEV1/FVC was significantly higher in group T (p ¼ 0.124, and p ¼ 0.017, respectively). Hemodynamic parameters of MAP and HR were lower in group P, but the differences were not significant (p > 0.05 for all) (►Figs. 3 and 4).
Discussion Poor pain control after thoracotomy operations may manifest with patient being unable to take adequate breaths and to cough forcibly, and finally this leads to retained secretions, atelectasis, hypoxemia, and infection.5 This emphasizes the importance of postthoracotomy analgesia. Paravertebral nerve block is a frequently used invasive method of postthoracotomy analgesia, though TENS offers some advantages, such as being noninvasive, nonaddictive, portable, and simple to use, and has been shown to reduce postoperative analgesic consumption.9 To the best of our knowledge, no study in the literature compares the effectiveness of these two treatment modalities for postoperative pain relief. The main findings of the current study include the following: (1) Patients who received PVB experienced less pain both at rest and while coughing and needed less opioid analgesic; (2) hemodynamic parameters did not differ among groups; however, FEV1/FVC
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Fig. 2 Comparison between the groups of visual analog scale (VAS) when coughing. p< 0.001 at all time points.
was significantly higher in patients who received TENS postoperatively. Erdogan et al10 investigated the TENS efficacy on postthoracotomy pain and respiratory function. The authors reported that patients for whom TENS was used in addition to intercostal nerve blockade had greater improvement in pulmonary function with less opioid requirements. Their VAS scores were less than 3 at rest and less than 5 when coughing at the 6 hour postoperatively. In our study, VAS scores were between 6 and 3 when coughing and between 5 and 2 at rest in the TENS group, whereas they were between 5 and 2 when coughing and between 3 and 1 at rest in group P after 6 hours postoperatively. Intercostal nerve blockage was used in both groups (control and TENS) intraoperatively. Perhaps this could explain the lower pain scores of patients in the early postoperative period. We used additional analgesics in both groups when VAS scores were more than 3. All the patients in group T needed an additional dose of analgesics postoperatively; however, 15 of 20 patients needed additional analgesic in group P. Unfortunately, we did not record how much and at what time this was given, which is one of the limitation of our study. The other limitations were that although we continued the analgesic treatments of TENS and paravertebral infusion (gradually decreased the concentration of local anesthetics) for 4 days, we recorded data only for the first 24 hours and also we did not mention complications related to pain, such as atelectasis in this study. We did not notice any side effect or intolerance except for minimal, unimportant discomfort due to TENS treatment in accordance with previous studies.10,11 Hemodynamic parameters were not significantly different between the groups.
Baki et al.
Declined functional residual capacity and the vital capacity values were found after thoracotomy procedures and pain has been shown as a major contributing factor.12 In a metaanalysis of trials assessing the pulmonary function following thoracic surgery, the most effective analgesic method for preservation of spirometric function was PVB.13 Our spirometric values recorded on the fifth day postoperatively were higher than the preoperative values and this increase was significant in the TENS group. Also, we found that PVB reduced postoperative pain and opioid requirements, but TENS was not as effective as PVB against severe postoperative pain. Likewise, Benedetti and collegues14 showed that TENS is effective in relieving mild or moderate acute postthoracotomy pain associated with muscle-sparing thoracotomy, median sternotomy, and video-assisted thoracoscopic surgery. PVBs are performed using several approaches, varying from a percutaneous needle below or above the transverse vertebral process for single shot or prolonged catheter infusion to visually guided placement of a catheter during surgery. Richardson et al15 compared epidural and paravertebral bupivacaine on postthoracotomy pain, respiratory function, and stress responses. Lower morphine consumptions and VAS values were reported in paravertebral group in their study. Continuous PVB has also been demonstrated to provide excellent postoperative analgesia when compared with single-shot paravertebral or intrapleural blocks after thoracotomy.16 In the study by Perttunen et al,17 extradural, paravertebral and intercostal blocks for postthoracotomy pain were compared; similar levels of pain, opioid consumptions, and respiratory function were noted in the three groups. PVB technique can be inserted under direct vision of the surgeon before the end of surgical procedures, it does not delay surgery as thoracal epidural block does, and saves precious time in the operating room. In the current study paravertebral catheters were placed by the surgeon at the end of the operation. The amount and concentration of local anesthetics performed in neuraxial blocks vary depending on the physician and institute. Because we did not have the chance to monitor local anesthetics plasma levels, we chose using the management of the amount in the literature.15 Meissner mentioned the use of TENS and acupuncture in his review, and found that the number of new high-quality studies on acupuncture and TENS in postoperative pain is restricted. As these techniques obviously do no harm, their use as adjunctive pain treatment approaches should be considered if conventional techniques fail.18 In our study,
Table 2 Pre- and postoperative 5th day FEV1 and FEV1/FVC values of treatment groups
FEV1 FEV1/FVC
Preoperative
Postoperative 5th day
Group P
2.94 0.86
2.81 0.69
Group T
3.07 0.78
2.52 0.9
Group P
75.31 8.65
79.45 9.38
Group T
79.3 7.32
85.9 6.78
Abbreviations: FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity. Note: Data expressed as mean SD, FEV1, and FEV1/FVC. Thoracic and Cardiovascular Surgeon
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Comparison of TENS and PVB for Postthoracotomy Pain Relief
Comparison of TENS and PVB for Postthoracotomy Pain Relief
4
5
6
Fig. 3 Mean arterial pressure (mm Hg). No significant differences between the groups regarding mean arterial pressure measured on the 1st, 4th, 8th, 12th, and 24th hours after the operation (p > 0.05).
7
8
9
10
11
Fig. 4 Heart rates of the groups. No significant differences were measured on the 1st, 4th, 8th, 12th, or 24th hours after the operation (p > 0.05).
TENS has beneficial effects for pain relief after thoracotomy without any side effects; however, it cannot provide sufficient pain relief when compared with PVB. Conflict of Interest None declared.
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13
14
15
References
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epidural analgesia: a prospective follow-up study. Acta Anaesthesiol Scand 2003;47(4):433–438 2 Yegin A, Erdogan A, Kayacan N, Karslı B. Early postoperative pain management after thoracic surgery; pre- and postoperative versus postoperative epidural analgesia: a randomised study. Eur J Cardiothorac Surg 2003;24(3):420–424 3 Casati A, Alessandrini P, Nuzzi M, et al. A prospective, randomized, blinded comparison between continuous thoracic paravertebral
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