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Table of Contents
ORIGINAL ARTICLE
Year : 2021  |  Volume : 15  |  Issue : 1  |  Page : 45-49

Continuous wound infusion as an alternative to continuous epidural infusion for postoperative analgesia in renal transplant surgery: A prospective randomized controlled trial


1 Department of Anaesthesia and Intensive Care, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Renal Transplant Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Date of Submission20-Aug-2020
Date of Acceptance27-Jan-2021
Date of Web Publication31-Mar-2021

Correspondence Address:
Dr. Sameer Sethi
Department of Anaesthesia and Intensive care, Postgraduate Institute of Medical Education and Research, Chandigarh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijot.ijot_105_20

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  Abstract 


Background: Pain management is often challenging in patients undergoing renal transplant owing to the various comorbidities. Epidural analgesia is currently the standard technique but is not without complications. Continuous wound infusion (CWI) is emerging as a simple and effective technique of postoperative analgesia. Therefore, the purpose of our study was to compare the efficacy of CWI with continuous epidural infusion (CEI). Methods: Forty-two patients undergoing renal transplant surgery were randomized to receive either CEI or CWI. The visual analogue score at rest and on movement was assessed. Opioid consumption, patient satisfaction, and complications were also assessed. Results: The pain scores measured at rest 4, and 8 h postoperatively were significantly lower in the CWI group.(2.45 ± 1.317) in CWI versus (3.45 ± 1.050) in CEI, P = 0.012 at 4 h, and (1.95 ± 1.146) in CWI versus (2.75 ± 0.786) in CEI, P = 0.014 at 8 h. The pain scores at other time points were lower in the CWI group but not statistically significant. The morphine used in the first 8 h was significantly higher in the CEI group. There was a higher incidence of hypotension in the CEI group (P = 0.028). The patient satisfaction and other side effects were comparable between the groups. Conclusion: Continuous wound infiltration is an effective technique for postoperative analgesia in renal transplant surgery and can be used as an alternative to epidural analgesia.

Keywords: Continuous epidural infusion, continuous wound infusion, postoperative analgesia, renal transplant


How to cite this article:
Narayan V, Sethi S, Kajal K, Singh S. Continuous wound infusion as an alternative to continuous epidural infusion for postoperative analgesia in renal transplant surgery: A prospective randomized controlled trial. Indian J Transplant 2021;15:45-9

How to cite this URL:
Narayan V, Sethi S, Kajal K, Singh S. Continuous wound infusion as an alternative to continuous epidural infusion for postoperative analgesia in renal transplant surgery: A prospective randomized controlled trial. Indian J Transplant [serial online] 2021 [cited 2021 Jul 30];15:45-9. Available from: https://www.ijtonline.in/text.asp?2021/15/1/45/312745




  Introduction Top


Pain following renal transplant is usually of moderate severity. Pain management is often challenging owing to the various comorbidities and is therefore inadequately managed.[1] Epidural analgesia although popular, carries a risk of epidural hematoma especially in those with platelet dysfunction and from the residual effect of heparin from dialysis. Hemodynamic instability, especially in those with poorly controlled hypertension can compromise the renal graft perfusion. Moreover, the insertion of an epidural catheter is technically demanding and has a high failure rate.[2]

Excessive use of opioids can lead to adverse effects such as nausea, vomiting, ileus, constipation, urinary retention, pruritus, ventilatory depression, and sedation which can delay recovery.[3] To overcome these limitations, various other modalities of pain management are being explored such as the transversus abdominis plane block.[4],[5]

Infiltration of the wound with local anesthetics is another simple and effective method but is limited by its short duration of action. To overcome this limitation, wound infusion catheters have been developed to provide a continuous infusion of local anesthetics for an extended period of time. Direct infusion of local anesthetics in the wound provides analgesia by directly inhibiting the noxious potentials generated from the peripheral nerve fibers and also by attenuating the local inflammation.[6] Ropivacaine is the local anesthetic of choice as it is less lipophilic and hence has a lower incidence of penetrating larger myelinated nerve fibers and causing inadvertent motor blockade when administered epidurally. The low lipophilicity is also associated with lower cardiovascular and central nervous system depressant effects.[7] The safety and efficacy of using 0.2% ropivacaine at 10 ml/h in epidural and wound infusion have been studied.[8]

Continuous wound infiltration has been studied in caesarean section,[9] colorectal surgeries,[10] thoracotomy,[11] prostatectomy,[12] and hepato-pancreatico-biliary surgeries[13] with variable results but has not been studied in renal transplant recipients.

The purpose of our study was to compare continuous wound infusion (CWI) with continuous epidural infiltration in renal transplant recipients. We hypothesized that CWI would provide better analgesia when compared with continuous epidural infusion (CEI).


  Methods Top


The study was approved by the Institutional Ethics Committee: NK/3869/MD/289. The study was registered under CTRI: REF/2017/11/016052. It was a single center, open label, randomized controlled trial conducted in a tertiary care hospital. It included patients aged 18–65 years undergoing renal transplant surgery. Patients refusing consent, INR >1.2, platelet count <100 000, allergy to local anesthetics, opioid addiction, and psychiatric disorders were excluded from the study.

After obtaining informed written consent, the patients were randomly allocated to CEI or CWI group using a computer-generated sequence. A preanesthetic evaluation was done the evening prior to surgery. The patients were trained to use the patient-controlled analgesia (PCA) pump and report pain using the visual analog scale (VAS).

CEI group: A 20-gauge epidural catheter was placed in the L1-L2 interspace prior to the induction of anesthesia. The proper placement of the catheter was confirmed by a standard test dose of 3 ml of 2% lignocaine with 5 μ/ml adrenaline. At the end of the surgery, a bolus of 10 ml of 0.2% ropivacaine was given, followed by an infusion at the rate of 10 ml/h. Hypotension following the bolus was treated with boluses of intravenous (IV) phenylephrine.

CWI group: A 60 cm Infiltralong catheter (Pajunk®, Germany) with multiple holes along the first 15 cm of its length was inserted using a 19 gauge split cannula, in the preperitoneal plane of the wound [Figure 1]. The patency of the holes was checked by flushing the catheter with saline before inserting it. After the closure of the wound, a 10 ml bolus of 0.2% ropivacaine was administered, followed by an infusion at 10 ml/h using a syringe pump.
Figure 1: Wound infiltration catheter placed along the length of the wound

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General anesthesia was induced with fentanyl 2 μg/kg, propofol 1–2 mg/kg, atracurium 0.5 mg/kg to facilitate endotracheal intubation. Oxygen, nitrous oxide, and 1%–2% isoflurane was used for maintaining anaesthesia. Muscle relaxant was repeated as and when necessary. 0.5 μg/kg fentanyl was repeated if the procedure exceeded 2 h or if there was tachycardia >100/min. Toward the end of the surgery, 1 g IV paracetamol and 4 mg IV ondansetron was administered. The patients were shifted to the renal transplant intensive care unit on emergence for care. All patients received IV PCA set to deliver 1 mg morphine per dose with a lockout interval of 20 min with no background infusion. Both epidural and wound catheters were removed after 48 h.

The VAS score was assessed at 4, 8, 12, 24, and 48 h after surgery, both at rest and during moving or coughing. The scores ranged from 0 to 10 with 0 signifying no pain and 10 being the worst imaginable pain. Patient satisfaction was measured at the end of 48 h on a 3 point Likert scale, 1-satisfactory, complete pain relief, 2-inadequate, moderate pain relief, and 3-unsatisfactory, and poor pain relief.

Total fentanyl used intraoperatively and 4 hourly postoperative morphine use was noted. Complications such as postoperative nausea and vomiting (PONV), pruritus, were recorded as present or absent. Respiratory rate <12/min was considered as respiratory depression and bradycardia as heart rate (HR) <50/min. Any catheter-related complications such as infection were noted.

Hypotension was considered as fall in blood pressure (BP) >20% from baseline or systolic BP <90 mmHg. Hypotension was managed with boluses if IV phenylephrine 50–100 μg. If the hypotension was attributed to hypovolemia owing to brisk diuresis often seen following transplant, fluid boluses were given. In case of persistent hypotension, the epidural infusion rate was halved and if severe, the infusion was discontinued.

Statistical analysis

Sample size was calculated based on the study by Bertoglio et al.[8] To detect a difference of 30% in the VAS scale between the groups, with an alpha error of 0.05 and a power of 80%, 18 patients were required for each group. However, 20 patients were allocated to each group, allowing a dropout rate of 10%. All data, such as age, HR, systolic blood pressure, diastolic blood pressure, and morphine consumption (in mg), were tabulated and checked for normalcy by Kolmogorov–Smirnov tests of normality. Discrete categorical data were tabulated as number or percentage. Continuous data normally distributed were represented as mean and standard deviation or median and interquartile range. Statistical analyses of VAS pain intensity difference between the groups were done by unpaired Student's t-test. The incidence of side effects and other complications and patient satisfaction were compared by the Chi-square test. Binary logistic regression was applied to find out any association of VAS scores and strongly predictable variables (P < 0.10 in univariate analysis) between study groups. P < 0.05 was considered as statistically significant at a 95% confidence interval. Statistical analysis was conducted using IBM® Statistical Package for Social Science version 22.0, IBM Corp., Armonk, NY, USA.

Patient consent

The patient consent has been taken for participation in the study and for publication of clinical details and images. Patients understand that the names, initials would not be published, and all standard protocols will be followed to conceal their identity.

Ethics statement

The study was approved by institutional ethics committee. No: INT/IEC/2017/1225. All protocols were followed as per Declaration of Helsinki.


  Results Top


A total of 42 patients were recruited to the study. One patient from the CWI group underwent re-exploration, during which the wound catheter had to be removed and hence was excluded from the study. One patient from the CEI group was excluded due to persistent hypotension necessitating the discontinuation of the epidural infusion. Twenty patients from each group were then assessed [Figure 2].
Figure 2: CONSORT diagram showing 42 participants allocated to continuous wound infusion and continuous epidural infusion, groups

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All patients were the American Society of Anesthesiologists III with end-stage renal disease. Age, sex, weight, height, and body mass index were comparable between the two groups as shown in [Table 1].
Table 1: Baseline characteristics of patients

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The VAS scores were significantly lower in the CWI group compared to CEI at 4 and 8 h postoperatively during both rest and movement [Table 2], [Table 3] and [Figure 3], [Figure 4]. The VAS measured subsequently, although lower in the CWI group, was not statistically significant.
Table 2: Visual analogue scores at rest

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Table 3: Visual analog score with movement

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Figure 3: Comparison of Visual Analogue Scale scores at rest

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Figure 4: Comparison of Visual Analogue Scale scores during movement

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Fentanyl used intraoperatively was comparable between the two groups. The morphine used in the first 8 h was significantly lower in the CWI group compared to the CEI group. The dose of morphine between 8 and 48 h was lower in the CWI group but not statistically significant [Table 4] and [Figure 5].
Table 4: Opioid consumption

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Figure 5: Comparison of postoperative morphine use

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The hemodynamics and patient satisfaction with the regimen were also not statistically significant as shown in [Table 5].
Table 5: Patient satisfaction scores

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The incidence of PONV was comparable between the two groups and managed with IV ondansetron. There were no complaints of pruritus or respiratory depression. There was a higher incidence of hypotension in the CEI group (8 vs. 2 in CWI, P = 0.028). One patient in the CWI group developed a hematoma at the incision site which was evacuated uneventfully. None of the patients developed wound infection [Table 6].
Table 6: Postoperative complications

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  Discussion Top


To the best of our knowledge, our study was the first to compare the postoperative analgesia provided by CWI with the epidural infusion in renal transplant recipients. A standard right iliac incision was employed in all cases. There was uniformity with respect to the length of the incision, duration, and type of surgery. This study demonstrates the superiority of CWI with epidural infusion in the first eight hours postoperatively and equally efficacious to epidural from 8 to 48 h postoperatively. The intensity of pain is higher in the immediate postoperative period and inadequate analgesia can lead to discomfort and anxiety. Patients in both groups had minimal pain (VAS 0–1) after 24 h postoperatively.

The morphine used through IV PCA was also significantly higher in the CEI group in the first 8 h postoperatively. The patient satisfaction with the analgesic regimen was not statistically significant between the two groups.

The lack of efficacy of wound infusion shown in previous studies may be attributed to the subcutaneous placement of the catheter, signifying the contribution of peritoneal irritation to postoperative pain. We chose to place the catheter in the preperitoneal plane based on a study by Beaussier et al.[10] This finding is supported in a recent meta-analysis by Mungroop et al.,[14] comparing preperitoneal and subcutaneous wound infusion in which preperitoneal placement of the wound catheters was found to provide superior analgesia in abdominal surgeries.

Hypotension is a known complication of epidural and the incidence was significantly higher in the CEI group; however, it was managed immediately and adequately and therefore there was no difference in the overall hemodynamics of the two groups. The use of wound infusion is beneficial in this subset of patients as hypotension can be detrimental to the functioning of the newly grafted kidney.

The dose of morphine used was not high in the two groups. There were no instances of respiratory depression. The incidence of PONV was comparable between the groups. There were no complaints of pruritus. None of the patients in the CEI group developed inadvertent sensory or motor blockade.

The dose of ropivacaine used in the study was 20 mg/h. We did not measure the plasma levels of ropivacaine but none of the patients developed any features of local anesthetic systemic toxicity. A study by Gottschalk et al.[15] comparing high (18.75 mg/h) and low (10/mg h) doses of ropivacaine in shoulder arthroscopies, the plasma ropivacaine levels always remained below the toxic threshold.

The wound infusion catheter used in the study is a multi-holed catheter with 60 holes placed 360° around and along the first 15 cm of its length and thus ensuring the uniform spread of the local anesthetic in the wound. The catheter was placed by the surgeon before the closure of the wound. The insertion of an epidural requires some degree of skill and expertise. The simplicity in the insertion of the wound catheter is an advantage especially in the obese and those with difficult spine anatomy, thoracic epidurals, and previous spine surgeries. It also obviates the discomfort caused when placing an epidural and the needle phobia which are the main reasons for the refusal of epidurals. However, there were no failed epidurals or premature removal in our study.

An indwelling wound catheter is a concern in transplant recipients receiving immunosuppression. Nevertheless, none of our patients developed wound infection.

The CWI can also be used in vascular surgeries where heparin is used in the perioperative period, contraindicating the use of neuraxial techniques. It can also be used in patients with altered hepatic function duration of action of opioids will be prolonged and coagulopathies which increase the bleeding risk with regional techniques. As the wound catheter is placed at the end of the surgery, it can be employed in cases when laparoscopic surgeries get converted to open surgeries.

Limitation of the study

A limitation of the study is that the wound catheter can be placed only at the end of surgery and hence cannot contribute to intraoperative analgesia. To make both the groups comparable, the epidural infusion was commenced only at the end of surgery.

Our study included patients with chronic kidney disease who are more susceptible to hemodynamic instability. The hypovolemia resulting from the brisk diuresis following the transplant combined with epidural could have contributed to the higher incidence of hypotension in this group.

The other limitation of the study is that blinding was not used. We did not use a sham wound catheter in the epidural group to enable the assessment infection resulting from an indwelling wound catheter.


  Conclusion Top


Continuous wound infiltration is a safe and effective technique and is better than epidural in the early postoperative period. Moreover, it can be used as an alternative to epidural more so in renal transplant recipients who present with platelet dysfunction and have a higher incidence of hemodynamic instability.

Financial support and sponsorship

Received institutional research grant for purchase of wound infusion catheters.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Freir NM, Murphy C, Mugawar M, Linnane A, Cunningham AJ. Transversus abdominis plane block for analgesia in renal transplantation: A randomized controlled trial. Anesth Analg 2012;115:953-7.  Back to cited text no. 4
    
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Farag E, Guirguis MN, Helou M, Dalton JE, Ngo F, Ghobrial M, et al. Continuous transversus abdominis plane block catheter analgesia for postoperative pain control in renal transplant. J Anesth 2015;29:4-8.  Back to cited text no. 5
    
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8.
Bertoglio S, Fabiani F, Negri PD, Corcione A, Merlo DF, Cafiero F, et al. The postoperative analgesic efficacy of preperitoneal continuous wound infusion compared to epidural continuous infusion with local anesthetics after colorectal cancer surgery: A randomized controlled multicenter study. Anesth Analg 2012;115:1442-50.  Back to cited text no. 8
    
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Ranta PO, Ala-Kokko TI, Kukkonen JE, Ohtonen PP, Raudaskoski TH, Reponen PK, et al. Incisional and epidural analgesia after caesarean delivery: A prospective, placebo-controlled, randomised clinical study. Int J Obstet Anesth. 2006;15:189-94.  Back to cited text no. 9
    
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Beaussier M, El'Ayoubi H, Schiffer E, Rollin M, Parc Y, Mazoit JX, et al. Continuous preperitoneal infusion of ropivacaine provides effective analgesia and accelerates recovery after colorectal surgery: A randomized, double-blind, placebo-controlled study. Anesthesiology 2007;107:561-8.  Back to cited text no. 10
    
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Mungroop TH, Veelo DP, Busch OR, van Dieren S, van Gulik TM, Karsten TM, et al. Continuous wound infiltration versus epidural analgesia after hepato-pancreato-biliary surgery (POP-UP): A randomised controlled, open-label, non-inferiority trial. Lancet Gastroenterol Hepatol 2016;1:105-13.  Back to cited text no. 13
    
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Mungroop TH, Bond MJ, Lirk P, Busch OR, Hollmann MW, Veelo DP, et al. Preperitoneal or subcutaneous wound catheters as alternative for epidural analgesia in abdominal surgery: A systematic review and meta-analysis. Ann Surg 2019;269:252-60.  Back to cited text no. 14
    
15.
Gottschalk A, Burmeister MA, Radtke P, Krieg M, Farokhzad F, Kreissl S, et al. Continuous wound infiltration with ropivacaine reduces pain and analgesic requirement after shoulder surgery. Anesth Analg 2003;97:1086-91.  Back to cited text no. 15
    


    Figures

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