記住我
ORIGINAL ARTICLE
Year : 2023 | Volume
: 24
| Issue : 1 | Page : 65-71
Efficacy of dexmedetomidine as an adjuvant with ropivacaine in USG guided erector spinae plane block for modified radical mastectomy surgery- prospective randomized double blind controlled study
Indira Kumari, Sandeep Sharma, Sandeep Kumar Ola, Krishna Boliwal, Santosh Choudhary, Vidhu Yadav
Department of Anaesthesiology, RNT Medical College, Udaipur, Rajasthan, India
Correspondence Address:
Dr. Krishna Boliwal
402, Gold Coast Apartment Near Bansi Paan, Bhopalpur, Court Circle, Udaipur - 313 001, Rajasthan
India
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/TheIAForum.TheIAForum_2_23
Background and Aims: Modified radical mastectomy (MRM) is associated with considerable acute postoperative pain and even chronic persistent pain. Erector spinae plane block (ESPB) is interfascial block for thoracic analgesia. This study was planned to evaluate efficacy of dexmedetomidine as adjuvant with ropivacaine in ESPB for postoperative analgesia in MRM surgery.
Materials and Methods: In this prospective randomized double-blind controlled study, 60 American Society of Anesthesiologists Grade I and II female patients, aged 18–60 years scheduled for MRM surgery under general anesthesia were randomly allocated into Group R and RD to receive ultrasound (USG)-guided ESPB with 20 ml 0.375% ropivacaine and 1 μg/kg dexmedetomidine added to 20 ml 0.375% ropivacaine, respectively. Visual Analog Score (VAS) was recorded at 0, 2, 4, 6, 8, 10, 12, and 24 h postoperatively. Duration of analgesia together with total number and amount of analgesic drug required was recorded in first 24 h postoperatively. Patient's satisfaction score was recorded on 10-point scale. Chi-square test, t-test, and Wilcoxon signed-rank test were applied where deemed appropriate. P <0.05 was considered statistically significant.
Results: VAS score was less in Group RD at all measured time points postoperatively. Duration of analgesia was prolonged in Group RD (683.00 ± 83.99 min vs. 620.63 ± 70.42 min). Total number and amount of intravenous diclofenac (rescue analgesic) was lower in Group RD (1.13 ± 0.57 vs. 1.46 ± 0.57, 85.00 ± 42.85 vs. 110.00 ± 42.85). Patients in group RD were better satisfied with their anesthesia experience (8 [8–9] vs. 8 [7–8], P = 0.00194). Group RD demonstrated a lower heart rate, systolic blood pressure, diastolic blood pressure, and mean blood pressure intraoperatively.
Conclusion: Dexmedetomidine as an adjuvant to ropivacaine in USG-guided ESPB for MRM surgery leads to lower postoperative pain scores, prolongs postoperative analgesia, reduces postoperative rescue analgesics requirements, and provides better hemodynamic stability and good patient satisfaction.
Keywords: Dexmedetomidine, erector spinae plane block, postoperative analgesia, ropivacaine
Modified radical mastectomy (MRM) is one of the commonly performed breast surgeries. MRM is associated with considerable acute postoperative pain and restricted shoulder mobility which leads to poor recovery, prolonged hospital stay, and even increased liability to chronic persistent pain in the form of post mastectomy pain syndrome.[1]
One important way of reducing postmastectomy pain is by providing multimodal analgesia. Various analgesic techniques can attenuate postoperative acute pain as local anesthetic infiltration, thoracic epidural anesthesia (TEA), intercostal nerve block, thoracic paravertebral block (TPVB), and pectoral plane block.[2],[3] However, all these techniques have their own short comings and limitations. TEA has several adverse effects such as hypotension, motor blockade, hematoma, and abscess. TPVB has a chance of epidural spread, pneumothorax, and multiple injections are needed if more than 4 dermatome analgesia is required.[4] Intercostal nerve block also necessitates multiple injection and has more chances of local anesthetic toxicity and pleural puncture leading to pneumothorax.[3]
The erector spinae plane block (ESPB) is a newly defined interfascial regional anesthesia block for thoracic analgesia which can be performed by superficial or deep needle approach.[5] It has been recommended to use the deep needle approach as drug is deposited deep to erector spinae muscle near the transverse process and at the origin of dorsal and ventral rami.[6] Previous studies have reported effective postoperative pain reduction and reduced postoperative opioid consumption after radical mastectomy surgery with ESPB, using plain local anesthetic without adjuvants.[2],[5],[7]
Since it is not always feasible to admit patients to a ward with indwelling peripheral nerve catheters, it is imperative to employ methods to increase the duration of analgesia with single-shot peripheral nerve blocks.[8] Dexmedetomidine is a potent α2 agonist and is now emerging as an adjuvant to regional anesthesia and analgesia. It can prolong the duration of the nerve block anesthesia when used with local anesthetic, and only has a few side effects.[9]
However, to the best of our knowledge, very few studies have been done so far which evaluated the effect of dexmedetomidine as an adjuvant with ropivacaine in ESPB in patients undergoing MRM surgery. We hypothesize that addition of dexmedetomidine to ropivacaine in ESPB will reduce the requirement of rescue analgesic consumption postoperatively. Therefore, we planned this study to evaluate the efficacy of dexmedetomidine as an adjuvant with ropivacaine for postoperative analgesia in patients posted for MRM surgery with primary outcome measured being the rescue analgesic consumption over first 24 h postoperatively. Secondary outcomes measured were number of rescue analgesic doses required in first 24 h postoperatively, duration of analgesia, intraoperative hemodynamics, and adverse effects, if any.
Materials and MethodsThis prospective randomized double-blind controlled study was conducted after taking approval from institutional ethical committee (RNT/STAT/IEC/2020/04) along with Clinical Trials Registry India registration (CTRI/2020/06/02560). Sixty American Society of Anesthesiologists (ASA) Grade I and II female patients, aged 18–60 years scheduled for MRM surgery under general anesthesia were allocated randomly to Groups R and RD according to computer-generated random number table [Figure 1]. Allocation to treatment groups was performed using the sealed opaque envelope technique. All patients and an investigator who was responsible for making study drug and postoperative follow-up were blinded to the randomization groups. Group R patients received ESPB with 20 ml of 0.375% Ropivacaine whereas Group RD patients received ESPB with 1 mcg/kg Dexmedetomidine added to 0.375% Ropivacaine upto total volume 20 ml. Ropin 0.75% 20ml ampoule and Dextomid 1 ml ampoule (100mcg/ml) ampoule, both from Neon laboratories Ltd were used for conducting the study.
Patients who had allergy to study drug, ASA III and higher, body mass index >35 kg/m2, coagulopathy or bleeding disorder, bradycardia, cardiac conduction block, psychiatric disease, pregnancy, infection at injection site, patients on β-adrenergic antagonist or antiplatelet drugs, and chronic analgesic usage were excluded from the study.
A pilot study conducted at our institution showed that the mean consumption of diclofenac sodium as rescue analgesic in patients undergoing MRM and receiving ESPB with ropivacaine 0.375% was 75 ± 28 mg in 24 h. We proposed that a reduction of requirement by 20 mg will be clinically significant. Therefore, for the present study, to have a power of 80% with α error of <0.05, 28 patients were required. To compensate for dropouts, 30 patients were included in each group.
All the patients under study were subjected to detailed preanesthetic evaluation which included detailed history taking, physical examination, and airway assessment. Written informed consent was obtained from all patients after explaining about the study purpose, advantages, and risks of procedure. During preoperative visits, all patients were familiarized with the use of Visual Analog Score (VAS) for pain assessment (0 = no pain, 10 = maximum imaginable pain).
Patients were kept nil by mouth for 6 h. All the patients were given tablet alprazolam 0.25 mg and capsule omeprazole 20 mg at 6 am on the day of surgery with sips of water. On arrival in preoperative area, intravenous (IV) access was secured with 18G IV cannula and standard monitoring was applied which included noninvasive blood pressure, electrocardiogram, and pulse oximetry.
The patients were then placed in sitting position. Under all aseptic precautions, transverse process of T4 vertebra was identified on operating site in paramedian sagittal orientation 2-3 cm lateral to midline by using a high frequency (5-13 MHz) linear probe of Ultrasound machine (Samsung, SAX7E). After identification of T4 transverse process and overlying Trapezius, Rhomboideus and Erector Spinae muscles, the targeted injection site was anaesthetized with 3-4 ml of 2% Lidocaine. A 120 mm, 22G needle (Stimuplex D: B Braun) was then inserted using in plane approach in cranial to caudal direction following same injection point until the tip lay in the interfascial plane deep to Erector Spinae muscle. Correct location of needle tip in the facial plane was then reconfirmed by injecting 0.5-1 ml saline and seeing the fluid lifting the erector spinae muscle off the transverse process while not distending the muscle. Study drugs were then injected according to group allocation and the distribution of drugs in both cranial and caudal direction was observed. After the block was performed, patients were asked to lie in supine position. Any block-related complications such as hypotension or vascular puncture were recorded. Then, patients were shifted to operation room.
Patients were premedicated with midazolam 1 mg, fentanyl 2 μg/kg, and diclofenac 75 mg intravenously. General anesthesia was induced with propofol 2 mg/kg IV and atracurium 0.5 mg/kg IV was administered to facilitate endotracheal intubation. Maintenance of anesthesia was achieved by isoflurane 0.8%–1% with oxygen and air mixture and intermittent dose of atracurium 0.1 mg/kg. Hemodynamic parameters were recorded just before induction and at 5, 15, 30, 45, 60, and 90 min post intubation. Thirty minutes before completion of surgery, ondansetron 4 mg IV was administered. After completion of surgery, residual neuromuscular block was reversed by neostigmine 2.5 mg with glycopyrrolate 0.5 mg IV and patients were then extubated. All patients were kept under observation in the ward for 24 h.
The VAS was recorded at 0, 2, 4, 6, 8, 10, 12, and 24 h postoperatively. Diclofenac 75 mg was administered intravenously as rescue analgesic to patients with VAS score ≥4. Duration of analgesia (time from the injection of anesthetic solution to first request of rescue analgesic drug) together with the total number and amount of analgesic drug required was recorded in the first 24 h postoperatively. The patients were observed for any complications like postoperative nausea and vomiting (PONV), pneumothorax, local anesthetic toxicity, hypotension, and bradycardia. Hypotension was defined as systolic blood pressure (SBP) <90 mmHg or fall of >20% from baseline value and treated with mephentermine 6 mg IV. Bradycardia was defined as Heart rate (HR) <60/min or fall of >20% from baseline value and treated with atropine 0.6 mg IV. Patient satisfaction score was recorded on a 10-point scale where 1 = very dissatisfied and 10 = very satisfied.[10]
The data were entered into MS EXCEL and analyzed using SPSS version 20 (International Business Machine Statistical Package for the Social Sciences, New York, USA). The data were assessed for normality of distribution using the Shapiro–Wilk test. Categorical data were presented as number (proportion) and compared with Chi-square test. Continuous variables were presented as mean ± standard deviation and compared using t-test. Ordinal data were presented as median (interquartile range) and compared using Mann–Whitney U-test. P < 0.05 was considered statistically significant.
ResultsThe mean age and weight of patients along with duration of surgery in two groups were comparable [Table 1].
Total dose of IV diclofenac used as rescue analgesic (primary objective) was significantly lower in Group RD as compared to Group R (85.00 ± 42.85 vs. 110.00 ± 42.85, P = 0.028) [Table 2]. Total number of rescue analgesic doses in Group RD (1 [1–1]) was also less than Group R (1 [1–2], P = 0.015). Duration of analgesia was prolonged in Group RD (683.00 ± 83.99 min) as compared to Group R (620.63 ± 70.42 min) (P = 0.003). In both groups, VAS score remained below 4 at all point of time, although the difference was statically significant at all point of time [Table 3].
On comparing hemodynamic variables, we noted that heart rate (HR) was comparable in both groups at baseline and after blockade however, a statistically significant lower HR was noted in group RD when observations were noted just before induction and at other time interval thereafter [Figure 2]. Systolic blood pressure (SBP), Diastolic blood pressure (DBP) and mean blood pressure (MBP) also showed statistically significant lower values in group RD after blockade, just before induction and at other time intervals thereafter [Figure 2] and [Figure 3].
Figure 2: Comparison of HR and MBP between the two groups. HR: Heart rate, MBP: Mean blood pressure
Figure 3: Comparison of SBP and DBP between the two groups. SBP: Systolic blood pressure, DBP: Diastolic blood pressureThe patient satisfaction score was statistically significantly higher in Group RD as compared to Group R (8 [8–9] vs. 8 [7–8], P = 0.00194). There were no incidences of PONV, pneumothorax, bradycardia, hypotension and LA toxicity in both the groups.
DiscussionIn this study, we found a significant reduction in total consumption of intravenous diclofenac as a rescue analgesic in RD group. Duration of analgesia significantly increased with addition of dexmedetomidine with ropivacaine for ESPB. SBP, DBP and MBP were also noted to be lower in RD group. Moreover, patient satisfaction score was statistically significantly higher in Group RD as compared to Group R.
Postoperative analgesia in breast surgery is difficult due to extensive nature of surgery and complex innervation of the breast.[11] Opioids, Paracetamol and Nonsteroidal antiinflammatory drugs have been administered as parentral analgesics but they have their own limitations. Opioids can cause nausea, vomiting, pruritus, and respiratory depression when they are used solely for analgesia.[12]
Regional anesthesia has a promising role in pain management after breast surgeries. A novel paraspinal regional anesthesia technique of ESPB, first described by Forero M et al,[6] promises to provide effective visceral as well as somatic analgesia after carcinoma of breast surgeries.[13]
ESPB offers many advantages. The point of injection is distant from the adjoining pleura, neuroaxis, and large vascular structures, thus imparting safety.[14] Performing the block is technically easy due to ultrasonographic targeting of transverse process. Moreover, the extent of erector spinae muscle through cervical, thoracic, and lumbar areas contributes to multiple dermatomal anesthesia of concerned side even with a single unilateral injection of 20–30 ml in adults.[15]
Cadaveric studies have shown that block at T5 level is sufficient to have unilateral multidermatomal sensory block ranging from T1 to L3.[16] Median and lateral pectoral nerves which are thought to be responsible for postmastectomy pain syndrome are not blocked by ESPB, if performed at a lower thoracic level (T5 or below). Hence, we decided to administer ESPB at T4 level and achieved adequate analgesia in our study. This may be possible due to selection of a higher injection point (level above T5) and injection of high volume of drug which might possibly have led to blockage of lateral and medial pectoral nerve along with the ventral and dorsal branches of the spinal nerves with adjoining communicating branches of the sympathetic chain.[17]
Various local anesthetics like Bupivacaine,[18],[19] Levobupivacaine,[20] Ropivacaine,[21] have been used for ESPB but duration of analgesia is for limited period. Hence various adjuvants like magnesium sulphate,[22] fentanyl,[23] morphine[24] and centrally acting α2 agonist like dexmedetomidine,[25] clonidine[26] are added to local anesthetics to prolong the duration of analgesia. We decided to evaluate analgesic efficacy of dexmedetomidine as an adjuvant to 0.375% ropivacaine in USG-guided ESPB for MRM surgery.
In our study, a significant reduction in total consumption of intravenous diclofenac as rescue analgesic was noted on adding dexmedetomidine to ropivacaine for ESPB. Our results find support in study conducted by Wang et al.[21] and Gao et al.[8] who observed a reduced rescue analgesic consumption in dexmedetomidine-ropivacaine group postoperatively. Decrease in requirement of rescue analgesics may lead to lesser side effects and a reduced economic burden for the hospital. Dexmedetomidine, an alpha 2 adrenergic receptor agonist causes a dose-dependent inhibition of C and Aα-pain fibers when applied directly to peripheral nervous system. It also acts on the locus ceruleus area, inhibiting nociceptive neurotransmission through the posterior horn of the spinal cord. Moreover, it also acts on the presynaptic membrane, inhibiting the release of norepinephrine, which in turn induces hyperpolarization and inhibits pain signals to the brain.[9]
In the present study, patients in ropivacaine-dexmedetomidine group had lower VAS scores postoperatively indicating a better pain control when dexmedetomidine was used as adjuvant in ESPB. Our study further corroborates earlier evidence from studies by Gao Z et al[8] on ESPB for VATS and Wang X et al[21]on ESPB for MRM surgery who reported a lower VAS scores when dexmedetomidine was added to ropivacaine.
In the present study, the duration of analgesia was prolonged on adding dexmedetomidine to ropivacaine in ESPB. Gao et al.[8] had also reported similar findings. Prolongation of pain free period facilitates early ambulation, early commencement of feeding and possibly early discharge from hospital, thus improving overall quality of patient care and recovery.
In the present study, patients in Group RD demonstrated a lower HR, SBP, DBP, and MBP as compared to Group R. However, this decrease in hemodynamic parameters was not clinically worrisome and required no therapeutic intervention. Similar lower values of hemodynamic variables were noted in studies conducted by Wang X et al[21] on ESPB with ropivacaine –dexmedetomidine combination and Gad M et al[20] on serratus plane block with levobupivacaine-dexmedetomidine combination. Dexmedetomidine has an antisympathetic effect and reduces the plasma catecholamines level. This leads to lowering of blood pressure and HR and thus provides hemodynamic stability.
In our study patients in group RD were better satisfied with their anesthesia experience. Gad M et al[20] also reported a better patient's satisfaction score in dexmedetomidine-levobupivacaine group compared with levobupivacaine group and control group in their study on serratus plane block for MRM surgery. Singh S et al[2] also noted in their study that patients who received US-Guided ESPB were more satisfied than control group.
Our study had few limitations. Intraoperative fentanyl consumption and depth of anesthesia were not assessed. Immediately after performance of block, general anesthesia was administered. Hence, dermatomal areas blocked and success rate of block could not be immediately assessed. Different doses of dexmedetomidine were not compared; hence, optimal dose of dexmedetomidine could not be determined. Plasma concentration of dexmedetomidine was not determined; hence, it could not be determined whether its action is due to systemic absorption or pure local effects. Manual injection of local anesthetic may have affected the spreading of local anesthetic due to different infusion rates and pressure.
In future studies, different additives, types, volume, and concentration of local anesthetic should be compared. Moreover, ESPB should be compared to other regional anesthesia techniques to identify optimal technique for chest surgeries.
ConclusionWe concluded that addition of 1mcg/kg of dexmedetomidine to 0.375% Ropivacaine in USG guided ESPB for MRM Surgery leads to lower postoperative pain scores, prolongs postoperative analgesia, delay time of request for first rescue analgesics, reduces postoperative rescue analgesics requirements and provides better hemodynamic stability along with providing good patients satisfaction without any adverse effects.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
留言 (0)