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Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 12  |  Issue : 3  |  Page : 700-704  

Efficacy of dexmedetomidine added to ropivacaine infilteration on postoperative pain following spine surgeries: A randomized controlled study


Department of Anaesthesia, Swami Rama Himalayan University, Dehradun, Uttarakhand, India

Date of Web Publication11-Sep-2018

Correspondence Address:
Dr. Nidhi Kumar
Associate Professor, Department of Anaesthesia HIMS, SRHU Dehradun Uttarakhand
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/aer.AER_89_18

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   Abstract 

Context: With modern lifestyle, there has been a steep increase in the number of low back pain patients in clinical practice. Lumbar microdiscectomy is one of the most common surgeries performed for this problem. Postoperative pain management is extremely important aspect of such advanced surgical technique among which wound infiltration is an efficient method. Aims: The aim of the study was to compare the efficacy of dexmedetomidine added to ropivacaine verses plain ropivacaine following wound infiltration in terms of pain scores, requirement of rescue analgesia, and related adverse effects. Settings and Design: Randomized, prospective, controlled, double-blind study over a period of 1 year in a tertiary care hospital. Materials and Methods: Sixty patients scheduled for lumbar discectomy were randomly allocated into two groups. Group A received wound infiltration with 30 ml 0.2% ropivacaine before wound closure and Group B received wound infiltration with 1ug/kg dexmedetomidine added to 30 ml of 0.2% ropivacaine before wound closure. Data retrieved were demographic data, visual analog scores, postoperative pain scores, rescue analgesia by patient controlled analgesia pump, recovery profile, and adverse effects. Statistical Analysis Used: Data were analyzed using statistical software SPSS version 22. Mann–Whitney test, Kruskal–Wallis test, and Chi-square test were used as applicable. Results: Demographic data were comparable between the groups. Requirement of rescue analgesia was significantly less in Group B where combination of dexmedetomidine and ropivacaine was given. Conclusions: Dexmedetomidine provided effective postoperative analgesia and reduced fentanyl consumption when administered in wound infiltration with ropivacaine.

Keywords: Dexmedetomidine, postoperative analgesia, spine surgeries, wound infiltration


How to cite this article:
Deshwal R, Kumar N, Sharma JP, Kumar R. Efficacy of dexmedetomidine added to ropivacaine infilteration on postoperative pain following spine surgeries: A randomized controlled study. Anesth Essays Res 2018;12:700-4

How to cite this URL:
Deshwal R, Kumar N, Sharma JP, Kumar R. Efficacy of dexmedetomidine added to ropivacaine infilteration on postoperative pain following spine surgeries: A randomized controlled study. Anesth Essays Res [serial online] 2018 [cited 2018 Dec 13];12:700-4. Available from: http://www.aeronline.org/text.asp?2018/12/3/700/240881


   Introduction Top


Microdiscectomy is performed in symptomatic patients whose disabling pain and functional impairment have failed to respond to adequate trials of conservative treatment. Microdiscectomy has been reported to result in early recovery of patient and quick return to work, hence considered as the gold standard for treating disc prolapse.[1]

Postoperative pain after microdiscectomy differs from other types of pain in that it is usually transitory with progressive improvement during a relatively short time course. This renders the condition more easily amenable to therapy than is the case for chronic pain.[2]

Effective postoperative pain control is an essential component of surgical patient care. So far, continuous epidural analgesia has been a commonly used method, as this technique is superior to intravenous (IV) analgesia regarding pain quality and incidence of side effects.[3] Since surgical pain originates from the surgical wound, a rational approach to perioperative pain treatment would be the use of local anesthetics (LA) at the site of surgery.[4]

Infiltrating LA into the skin and subcutaneous tissue results in the spread of drug, thus blocking nociceptive inputs.[5] Dexmedetomidine is a selective α2 adrenoreceptor agonist used as a sedative and adjuvant anesthetic.[6] We hypothesized that adding dexmedetomidine to ropivacaine for wound infiltration could enhance the analgesic efficacy of ropivacaine. We designed this study with the aim of comparing the postoperative pain relief that could be achieved by adding dexmedetomidine as an adjuvant to ropivacaine for wound infiltration in patients undergoing microdiscectomy.


   Materials and Methods Top


After Institutional Ethical Committee approval and patient's informed written consent, this prospective, randomized, controlled, double-blind study was conducted on 60 patients of either sex, patients physical status American Society of Anesthesiologists (ASA) Classes I and II between 18 and 60 years of age posted for microdiscectomy surgeries. The study was conducted in the tertiary care hospital over a period of 1 year.

Inclusion criteria were symptomatic patients whose disabling pain has failed to respond to conservative treatment and patients with unilevel disc prolapse. Exclusion criteria included patients with body mass index more than 30 kg/m2, presence of cardiac disease, psychiatric illness so as to unable to understand pain scores and patient controlled analgesia (PCA) pumps, allergy to the drug being used, and patients on chronic analgesics.

Randomization into one of the two groups (Group A or group B) was based on a computer-generated random table. The details of the series were unknown to the investigators, surgeon, and patient. The group assignments were kept in a set of envelope with only the case number on the outside. Before surgery, the appropriate numbered envelope was opened by the nurse not included in the study; the card inside determined whether the patient would be in Group A or Group B. Ropivacaine or ropivacaine with dexmedetomidine was then prepared by the nurse with sterile gloves in the form of syringes labeled with the case number. For every patient, a new vial of ropivacaine and dexmedetomidine was opened.

Group A received infiltration of 30 ml 0.2% ropivacaine at the surgical site before closure of the wound. Group B received infiltration of 30 ml 0.2% ropivacaine and 1 μg/kg of dexmedetomidine at the surgical site before wound closure.

All selected patients underwent routine preanesthetic evaluation which included complete history, physical examination, and routine laboratory investigations. The patients were explained about the procedure of wound infiltration, visual analog scale (VAS), and PCA pump.

One night before the surgery, patients were premedicated with oral alprazolam 0.5 mg, oral ranitidine 150 mg, and metoclopromide 10 mg. These drugs were repeated with small sips of water 2 h before the surgery. Skin sensitivity test with local anesthetic solution to be used in the patient was done in preanesthetic area.

Patients were preoxygenated with 100% oxygen for 3 min and fentanyl 2 μg/kg IV, followed by propofol 2 mg/kg IV was given. After confirming bag mask ventilation, patients were given vecuronium 0.1 mg/kg IV. Intermittent positive pressure ventilation was done for 3 min, after which endotracheal intubation using a laryngoscope and appropriate size endotracheal tube was done. Correct placement of endotracheal tube was confirmed with capnography and patients were put on controlled ventilation with appropriate settings using Dragger Fabius GS Workstation. Patients were maintained on a combination of oxygen, nitrous oxide, and sevoflurane at 1–1.5 MAC with a flow of 2 l/min. Incremental doses of fentanyl as 1 μg/kg was given every hour intraoperatively.

Intraoperative monitoring included electrocardiogram, noninvasive blood pressure, oxygen saturation, and end-tidal carbon dioxide through the use of monitor Vista 120.

Before the incision was sutured, the test drug which was previously prepared was infiltrated into the tissue around the incision including muscle and subcutaneous tissue. This was done by the operating surgeon under all aseptic precautions. To minimize surgeon and anaesthetist bias, both were kept same for all the cases. After completion of the surgery, patients were reversed with 100% oxygen. Neostigmine and glycopyrrolate were both given in weight appropriate dosage.

Postoperative breakthrough pain was relieved by PCA pump using fentanyl through IV route which was set to deliver 25 μg IV dose of fentanyl with a lockout interval of 15 min and maximum dose of 400 μg in any 4 h period and with no continuous background infusion.

After surgery, patients were evaluated by the VAS score (0 – no pain, 1–3 mild pain, 4–7 moderate pain, and 8–10 severe or worst imaginable pain) and postoperative pain score (PPS) (0 = no pain; 1 = moderate pain only when moving; 2 = moderate pain at rest, severe pain when moving; and 3 = constant severe pain) which were recorded at time 0 min, 30 min, 1 h, 2 h, 4 h, 6 h, 12 h, and 24 h postoperatively. The pain scores were used to evaluate the quality of analgesia in two situations “static pain” when the patients were restricted in bed, without moving and “dynamic pain” when the patient was made to log roll in his bed 6 h after operation.

PCA pump press number and total fentanyl consumption in 24 h postoperatively were recorded in both the groups.

Recovery profile in terms of time of extubation in minutes after completion of surgery, time when patient starts following verbal command and orientation time were recorded. Sedation was measured by Ramsay Sedation Score RSS (Grade 1 – patient appears anxious, agitated, or restless, Grade 2 – patient is cooperative, tranquil, and oriented, Grade 3 – patient responds to verbal command, Grade 4 – patient is asleep and shows response only to light, glabellar tap, or loud auditory stimuli, Grade 5 – patient is asleep and sluggish response to above, and Grade 6 – patient is asleep and shows no response to above).[7]

Adverse effects if any were noted, including nausea and/or vomiting, were treated with ondansetron 0.1 mg/kg IV. Hypotension (mean arterial pressure <20% of baseline or <60 mmHg) was treated with an infusion of normal saline and if necessary an IV injection of ephedrine 5–10 mg incremental doses was administrated. Bradycardia (heart rate <60 beats/min) was treated with i.v atropine 0.01–0.02 mg/kg bolus.

In the present study, primary objective was to assess VAS pain score (static and dynamic) and total fentanyl consumption in 24 h postoperatively. Secondary outcomes included PPS score, recovery profile of the patient, level of sedation, and adverse effects.

Data were analyzed using statistical software SPSS version 22 (IBM, SPSS statistical base: SPSS South Asia Pvt. Ltd, Bengluru, Karnataka, India). Qualitative data were expressed in terms of frequency and percentage. Quantitative data were expressed in terms of median interquartile ratio (IQR). Hemodynamic changes were assessed by repeated measure ANOVA. Extubation time was compared by one-way ANOVA. Adverse effects were tested by Chi-square test and P < 0.05 was considered statistically significant. Pain/VAS was compared by Kruskal–Wallis test.


   Results Top


A total of 62 patients were included in the study. One patient in the placebo group declined to participate in the postoperative period, and in one patient of the same group, the data collection was incomplete. Thus, sixty patients completed the study protocol [Figure 1]. Both groups were similar with respect to patient's demographic characteristics, patient's physical status (ASA), and duration of surgery [Table 1]. Patients receiving dexmedetomidine by infiltration had significantly lower VAS scores at rest [Table 2]. On analyzing VAS dynamic scores postoperatively for 24 h, it was observed to be significantly decreased (P< 0.05) in patients receiving dexmedetomidine [Table 3]. High scores for PPS were seen in Group A (Median IQR 2.5 [1.0–3.0]) while subjects in Group B had lower scores (Median IQR 1.0 [1.0–2.0]).
Figure 1: Consort flow diagram

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Table 1: Demographic characteristics and duration of surgery

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Table 2: Comparison of static visual analog scale score (median interquartile range) between two groups at different time interval

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Table 3: Comparison of dynamic visual analog scale score between two groups at different time interval

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Fentanyl consumption during the first 24 h was significantly less in Group B than in Group A [Table 4]. As far as sedation is concerned, none of the patients in both the groups had a sedation score (median IQR) more than 3.0 (2.0–4.0). Recovery profile [Table 5] was comparable in both the groups. No side effects such as hypotension and bradycardia were seen in both the groups. No incidence of nausea, vomiting, respiratory depression, and neurological deficit was present in the first 24 h. No incidence of wound infection was seen till the day of suture removal.
Table 4: Fentanyl consumption in μg and total patient controlled analgesia pushes in 24 h

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Table 5: Recovery profile of both groups

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   Discussion Top


The study demonstrated an overall significant analgesic efficacy of dexmedetomidine given in infiltration with ropivacaine in spine surgeries. On analyzing VAS static and dynamic scores postoperatively for 24 h, it was observed to be significantly decreased (P< 0.05) in Group B as compared to Group A signifying good pain control in patients receiving dexmedetomidine. A recent study done by Abd El-Hamid AM et al. compared the postoperative analgesic effect of IV dexmedetomidine with a combination of dexmedetomidine and bupivacaine wound infiltration for lower segment cesarean section. According to them, surgical wound infiltration is a better technique as it avoids the adverse hemodynamic effects of IV administration of drugs. Additional analgesic requirement and total demand for PCA pump were higher in control group which did not receive dexmedetomidine.[8]

Singh et al. studied the effect of adding dexmedetomidine with bupivacaine in wound infiltration in abdominal hysterectomy and found that dexmedetomidine in a dose of 1.0 μg/kg provided superior pain relief and decreased analgesic demand in postoperative period compared to wound infiltration with bupivacaine alone.[9]

The mechanisms of the analgesic actions of α2 agonists have not been fully elucidated. It acts on both supraspinal and spinal levels to modulate the transmission of nociceptive signals in the central nervous system.[10] α2-agonists also act peripherally to reduce nociceptive transmission, leading to analgesia. The activation of inwardly rectifying G1-protein-gated potassium channels results in membrane hyperpolarization, decreasing the firing rate of excitable cells. This is considered a significant mechanism of the inhibitory neuronal actions of α2-adrenoceptor agonists. Another prominent physiologic action ascribed to α2-adrenoceptors is their reduction of calcium conductance into cells, thus inhibiting neurotransmitter release. This effect involves the direct regulation of calcium entry through N-type voltage-gated calcium channels.[11]

Assessment of postoperative pain by counting the PCA pump-press number and total fentanyl consumption in 24 h showed that, in the fi rst 2 h postoperatively, there were no pump press numbers in Group B. The total number of pushes were significantly less in Group B. The total fentanyl consumption in 24 h was 62% less in dexmedetomidine group.

As the postoperative pain is complex problem, it is almost impossible to control pain with unimodal approaches. Rational approach to the treatment of postoperative pain is, therefore, to combine different treatment modalities, working at different pain mechanisms, to improve analgesia, and potentially to reduce side effects.

A recent study conducted by Forastiere et al. confirmed that wound infiltration as a part of multimodal approach was efficient in the patients undergoing open nephrectomy with intercostals incision.[12] Our results are in accordance with the work done by Kang H et al, who studied the effect of dexmedetomidine added to preemptive ropivacaine infi ltration on postoperative pain after inguinal herniorraphy. They found that the VAS scores were lower in dexmedetomidine group (RD) than in placebo group (RO) in 24 h postoperatively.[6]

Wound infiltration is an accepted method of postoperative analgesia in the invasive and painful procedures such as cesarean delivery, orthopedic procedures, lumbar spine surgery, after hip and knee replacement, shoulder surgery, and cardiothoracic surgical procedures. It is currently an important part of multimodal pain treatment.[13],[14]

In our study, the purpose of using PCA pump postoperatively combined with infiltration technique was to provide early mobilization which improves outcome by shortening length of hospital stay.

In our study, patients in Group B had a sedation score of 2 and 3 and were cooperative and tranquil probably because they were pain free. However, Group A patients had a sedation score of 1 and 2 and were anxious and agitated. This is in agreement with the work of Abd El-Hamid AM et al, who found similar sedation scores in infiltrated dexmedetomidine group as in ours.[8] Activation of the α2-adrenoceptor in the brain and spinal cord inhibits neuronal firing, causing hypotension and bradycardia, but in our study, the incidence of hypotension and bradycardia was not seen in both the groups. Dogrul and Uzbay demonstrated that topical administration of clonidine elicits antinociception by blocking the emerging pain signals at peripheral terminals through α2-adrenoreceptors without producing the undesirable central side effects observed after systemic administration.[15]

The time to verbal response and extubation time were similar in Group A and B. In Group B, patients had greater overall stability and pain control in the postoperative period.

There was no incidence of surgical wound infection as observed in patients till the time of suture cutting. Although only a few authors presented the data on the postoperative surgical complications, no one of them confirmed significant positive correlation between wound instillation and infections.[16] However, LA increases wound perfusion and oxygenation enhancing wound healing.[5]

The limitations of our study are lack of pain control analysis over more than 24 h. Second single-dose local anesthetic and dexmedetomidine analysis was done instead of multiple dose analysis.


   Conclusions Top


Single shot wound infiltration technique proved to be better in relation to its cost-effectiveness, lesser opioid consumption, and improved pain relief. Dexmedetomidine infiltration appears to be a promising and safe adjunct for postoperative pain control in spine surgeries with preserved hemodynamic stability and lack of sedation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Apostolides PJ, Jacobowitz R, Sonntag VK. Lumbar discectomy microdiscectomy: “the gold standard”. Clin Neurosurg 1996;43:228-38.  Back to cited text no. 1
    
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Schoenfeld AJ, Weiner BK. Treatment of lumbar disc herniation: Evidence-based practice. Int J Gen Med 2010;3:209-14.  Back to cited text no. 2
    
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Rodgers A, Walker N, Schug S, McKee A, Kehlet H, van Zundert A, et al. Reduction of postoperative mortality and morbidity with epidural or spinal anaesthesia: Results from overview of randomised trials. BMJ 2000;321:1493.  Back to cited text no. 3
    
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Kristensen B, Karacan H, Agerlin M, Nimb L, Stentoft J, Tuxø J, et al. High-volume infiltration analgesia in major lumbar spine surgery. J Anesth Clin Res 2014;5:450.  Back to cited text no. 4
    
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Singh A, Jindal P, Khurana G, Kumar R. Post-operative effectiveness of continuous wound infiltration, continuous epidural infusion and intravenous patient-controlled analgesia on post-operative pain management in patients undergoing spinal surgery. Indian J Anaesth 2017;61:562-9.  Back to cited text no. 5
[PUBMED]  [Full text]  
6.
Kang H. The effect of dexmedetomidine added to preemptive ropivacaine infiltration on post-operative pain after inguinal herniorrhaphy. Eur Surg 2012;44:274-80.  Back to cited text no. 6
    
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Ramsay MA. Acute postoperative pain management. Proc (Bayl Univ Med Cent) 2000;13:244-7.  Back to cited text no. 7
    
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Abd El-Hamid AM, Alrabiey MI, Abd El-Fattah MH. A comparison of the postoperative analgesic effects of intravenous dexmedetomidine with a combination of dexmedetomidine and bupivacaine wound infiltration for lower segment cesarean section: A prospective, randomized study. Ain Shams J Anaesthesiol 2016;9:235-9.  Back to cited text no. 8
    
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Singh S, Prasad C. Post-operative analgesic effect of dexmedetomidine administration in wound infiltration for abdominal hysterectomy: A randomised control study. Indian J Anaesth 2017;61:494-8.  Back to cited text no. 9
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10.
Nakamura M, Ferreira SH. Peripheral analgesic action of clonidine: Mediation by release of endogenous enkephalin-like substances. Eur J Pharmacol 1988;146:223-8.  Back to cited text no. 10
    
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Birnbaumer L, Abramowitz J, Brown AM. Receptor-effector coupling by G proteins. Biochim Biophys Acta 1990;1031:163-224.  Back to cited text no. 11
    
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Forastiere E, Sofra M, Giannarelli D, Fabrizi L, Simone G. Effectiveness of continuous wound infusion of 0.5% ropivacaine by on-Q pain relief system for postoperative pain management after open nephrectomy. Br J Anaesth 2008;101:841-7.  Back to cited text no. 12
    
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Bianconi M, Ferraro L, Traina GC, Zanoli G, Antonelli T, Guberti A, et al. Pharmacokinetics and efficacy of ropivacaine continuous wound instillation after joint replacement surgery. Br J Anaesth 2003;91:830-5.  Back to cited text no. 13
    
14.
Stringer BW, Singhania AK, Sudhakar JE, Brink RB. Serum and wound drain ropivacaine concentrations after wound infiltration in joint arthroplasty. J Arthroplasty 2007;22:884-92.  Back to cited text no. 14
    
15.
Dogrul A, Uzbay IT. Topical clonidine antinociception. Pain 2004;111:385-91.  Back to cited text no. 15
    
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Kvolik S, Kristek J, Sakic K, Takac I, Gulam D. A wound infiltration as a method of potoperative analgesia. Period Boil 2009;111:241-6.  Back to cited text no. 16
    


    Figures

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    Tables

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



 

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