|Year : 2020 | Volume
| Issue : 1 | Page : 9-13
Effect of adding of dexmedetomidine to local anesthesia in external dacryocystorhinostomy patients
Mohamed A Nassef1, Ahmed F Gabr2, Sameh A Ahmed3
1 Department of Ophthalmology, Fayoum University, Fayoum, Egypt
2 Department of Ophthalmology, Aswan University, Aswan, Egypt
3 Department of Anesthesiology and Intensive Care, Faculty of Medicine, Tanta University, Tanta, Egypt
|Date of Submission||18-Sep-2019|
|Date of Acceptance||12-Jan-2020|
|Date of Web Publication||15-May-2020|
FRCSEd, MD Ahmed F Gabr
19 Saif El-Dawla Street, Tanta
Source of Support: None, Conflict of Interest: None
Purpose The aim was to study the efficacy and safety of addition of dexmedetomidine to local anesthesia (LA) for patients undergoing external dacryocystorhinostomy (DCR).
Patients and methods A total of 70 adult patients who presented for external DCR were included in this prospective double-blinded study. They were randomly distributed into two equal groups. All patients received LA with 8 ml mixture, composed of 3.5 ml of lidocaine 2% without epinephrine and 3.5 ml of plain bupivacaine 0.5%. Either 1 ml normal saline (0.9%) or that containing 20 µg dexmedetomidine was added to the mixture for each group. The onset and the duration of sensory blockade as well as perioperative sedation were verified. Visual analog score was evaluated in the postoperative period till 12 h postoperatively. Anesthesia-related perioperative complications and patient satisfaction were also reported.
Results Dexmedetomidine added to a LA block in external DCR significantly decreased the onset of anesthesia to 2.23±2.11 min (P=0.015) and increased the duration of sensory block to 200.45±37.98 min (P=0.0001). In addition, it significantly decreased the postoperative pain score 6–8 h postoperatively (P<0.05). Moreover, increased sedation level and patient satisfaction were noted (P<0.05), without significant increase in the incidence of adverse effects or complications.
Conclusion Addition of low-dose dexmedetomidine to LA infiltration in external DCR hastens the onset and prolongs the effective period of the sensory block. Enhancement of postoperative analgesia, increased perioperative sedation. and improved satisfaction of the patients were achieved without significant complications.
Keywords: dacryocystorhinostomy, dexmedetomidine, local anesthesia
|How to cite this article:|
Nassef MA, Gabr AF, Ahmed SA. Effect of adding of dexmedetomidine to local anesthesia in external dacryocystorhinostomy patients. J Egypt Ophthalmol Soc 2020;113:9-13
|How to cite this URL:|
Nassef MA, Gabr AF, Ahmed SA. Effect of adding of dexmedetomidine to local anesthesia in external dacryocystorhinostomy patients. J Egypt Ophthalmol Soc [serial online] 2020 [cited 2020 Jun 5];113:9-13. Available from: http://www.jeos.eg.net/text.asp?2020/113/1/9/284339
| Introduction|| |
Traditionally, post-saccal obstruction of lacrimal passage is treated with external dacryocystorhinostomy (DCR) that is performed under general anesthesia. However, more recently, there has been a great shift toward carrying out the procedure under local anesthesia (LA) ,.
Although control of blood loss and inadequate block duration is a concern ,, LAs have many advantages, as their use is economic and associated with decreased systemic complications and prolonged postoperative pain-free period ,.
To enhance analgesic and sedative characteristics of LA, many agents such as dexmedetomidine could be added ,.
Although previous studies evaluated the addition of dexmedetomidine to many LA agents in different body regions, there is a lack of available studies evaluating its role in lacrimal region block ,,,,.
This work was intended to study addition of dexmedetomidine to LA for patients undergoing external DCR regarding the effect on sensory blockade, postoperative analgesia, as well as the occurrence of complications.
| Patients and methods|| |
In this prospective randomized study, 70 patients were randomized by an independent researcher who randomly allocated them into two groups of equal numbers (35 cards for dexmedetomidine and 35 for normal saline in closed opaque envelopes). Study protocols were all approved by the Ethics Committee. Patients aged 18 years or older, devoid of or with controlled systemic conditions and appointed for routine external DCR were included. Informed consents were obtained from the patients following full explanation about the nature of the medications used. This study was performed following the tenets of Declaration of Helsinki. Approval by the Institutional Review Board was acquired and confidentiality of study and patients data was assured.
Patients having local infection, previous orbital trauma, and allergic reaction or complications of the LA were excluded. Exclusion was extended also to those with coexistence of diagnosed coagulopathy, uncontrolled systemic disease, unconsciousness as well as uncooperative patients.
Included patients had full ophthalmological and preoperative anesthetic assessments. They were randomly divided into two groups. Each patient was given lacrimal block composed of combination of equal quantities of lidocaine 2% (Xylocaine; AstraZeneca, Cambridge, UK) and bupivacaine 0.5% (Marcaine; AstraZeneca). For group A, 1 ml of 0.9% NaCl was added to act as control, whereas 1 ml of normal saline containing 20 µg dexmedetomidine (Precedex; Hospira, Lake Forest, Illinois, USA) was added to group B. The anesthetic mixture was arranged in identical syringes and introduced in sealed package by an independent anesthesiologist.
Perioperatively, oxygen saturation, blood pressure, and ECG were monitored, and oxygen supply to the patients was maintained through nasal cannula. Equal injections of LA (2 ml each) were given to infratrochlear area, infraorbital area, 5 mm above the medial canthal tendon to a depth of 15–20 mm, and subcutaneously beneath the site of incision at the side of the nose  ([Figure 1]). Tetracaine-oxymetazoline nasal spray (Kovanaze; Renatus, USA) was used in the ipsilateral nasal cavity to produce anesthesia and decongestion of the nasal mucosa.
|Figure 1 Injection sites of local anesthesia. (a) Infratrochlear region; (b) injection above medial palpebral ligament; (c) infraorbital region; (d) incision site.|
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Evaluation of the sensory block was started 1, 3, 5, 7, 9, and 10 min following injection of the LA mixture by the abolishment of the pinprick reflex. Failure of abolishment of the pinprick reflex within 20 min was considered as a failure of the block, which required conversion to general anesthesia, and the patient is excluded. The time lapse between complete injection of LA till abolishment of pinprick test (sensory block onset time) and intermission between that time and the commencement of postoperative pain (duration of the sensory block) were assessed.
Postoperatively, the visual analog score (VAS) was used for assessment of pain severity. Evaluation was done at first 4 and then every 2 h up to 12 h postoperatively. VAS scores greater than or equal to 4 justified the use of 1000 mg paracetamol (Perfalgan; Bristol-Myers Squibb, USA) by intravenous infusion every 6 h.
Perioperative complications and intraoperative blood loss were reported. Pain on injection, nausea and vomiting, bradycardia (decrease in the heart rate below 50 beats/min), hypotension (decrease in the baseline value 20% or more), and hypoxemia (decrease in the oxygen saturation below 90%) were monitored. Bradycardia was managed by intravenous atropine sulfate 0.3 mg (Atropine; Misr Co., Cairo, Egypt), whereas hypotension was managed by ephedrine sulfate 10 mg intravenous (Ephedrine; Misr Co.) and intravenous infusion of lactated Ringer solution.
Assessment of sedation level perioperatively was done using the Ramsay sedation score measured quarter hourly during surgery, then every 2 h for 12 h after completion of surgery .
Degree of patient satisfaction was evaluated 12 h postoperatively using scale composed of four points by asking the patients to give score of their satisfaction regarding postoperative analgesia.
Calculation of sample size was carried out referring to earlier studies ,. The result of this study was statistically analyzed using the arithmetic mean, SD, the unpaired Student t-test, Mann–Whitney test, and Fisher’s exact test when appropriate. P value less than 0.05 was considered significant. All tests were done using SPSS (Version 16.0; SPSS Inc., Chicago, Illinois, USA).
| Results|| |
A total of 70 patients fulfilling the inclusion criteria were randomly allocated to either control group or dexmedetomidine group, with successful obtaining of all the required data from the studied patients.
No significant differences were found between both the groups regarding surgical characteristics of the patients. Grave complications had not been encountered in both groups with statistically insignificant difference regarding frequency of minor incidents such as nausea, vomiting, soreness at site of local injection, hypotension, and/or bradycardia (P>0.5). There were also no significant differences between patients of both groups regarding mean blood loss ([Table 1]).
Compared with the control, sensory block onset took place significantly more rapidly, and its duration was significantly prolonged in dexmedetomidine group (P=0.015 and 0.0001, respectively).
Furthermore, VAS had been found to be significantly lower postoperatively in dexmedetomidine group compared with the control one. This occurred at sixth and eighth hour, with P values of 0.009 and 0.002, respectively. Immediately postoperatively and after 1, 2, 4, 10, and 12 h postoperatively, no significant differences in VAS score were found (P˃0.05) ([Table 2]).
|Table 2 Characteristic features of the sensory block and the postoperative pain in the studied groups|
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The Ramsay sedation score was used to evaluate patient’s sedation. Patients in the dexmedetomidine group had statistically significant increase in sedation level compared with the patients in the control group at 30 and 45 min intraoperatively, as well as at second hour, fourth hour, sixth hour, and eighth hour postoperatively (P<0.004 and <0.0001). No significant differences were noted between sedation level of the patients at 15 min as well as 10 and 12 h following surgery (P˃0.05).
Regarding patient satisfaction with the perioperative analgesia, dexmedetomidine group was superior to control group regarding this aspect (P=0.0012).
| Discussion|| |
Dexmedetomidine mechanism of loco-regional analgesia is not fully understood till now. It is thought that its analgesic effect is carried out through both central and peripheral mechanisms . Centrally at the dorsal root neuron, it acts through substance P release inhibition at the nociceptive pathway and stimulation of the α-2 adrenergic receptors at the locus coeruleus . Peripherally, it decreases norepinephrine release at the peripheral nerve fibers through stimulation of peripheral α-2 adrenergic receptors, resulting in abolishment of the nerve fiber action potential .
Dexmedetomidine in loco-regional anesthesia use in regional anesthesia in a dose of 20–100µg was reported to be safe by previous animal and human studies ,,,. Multiple available studies revealed the prolonged sensory block and improved postoperative analgesia when combining dexmedetomidine with different LA techniques, as in local intravenous anesthesia  and in axillary brachial plexus block .
In the present study, the use of 20 µg dexmedetomidine in addition to LA agents as a local infiltration anesthesia for patients undergoing external DCR was found to reduce the onset of sensory blockade and extend its duration significantly. Pain score was decreased 6 and 8 h postoperatively, with increased level of patients’ sedation and satisfaction.
Ghali et al.  evaluated dexmedetomidine use with sub-tenon block in vitreoretinal surgeries and reported significantly longer motor and sensory block duration compared with levobupivacaine alone, with significantly higher levels of sedation intraoperatively as well as after12 h postoperatively. They also declared provision of more effective postoperative analgesia with dexmedetomidine use. Similar results were obtained with addition of dexmedetomidine 20 µg to LA agents during peribulbar block in patients with vitreoretinal surgeries .
Furthermore, using dexmedetomidine in neuraxial anesthesia was evaluated by many trials that founded prolonged sensory block and improved postoperative analgesia with its use, such as Yousef et al. , in combined spinal epidural anesthesia, Mohta et al.  in paravertebral block, Vorobeichik et al.  in brachial plexus nerve blocks, Zeng et al.  in epidural analgesia, Zhao et al.  in epidural labor analgesia, and Das et al.  in spinal anesthesia. Additionally, several systematic reviews discussing the additional effect of adjuvant dexmedetomidine were found to support the findings of the current study ,,.On the contrary, some investigators reported no additional effect on sensory block duration with the use of dexmedetomidine in addition to lidocaine in total intravenous anesthesia . Moreover, others assessed additive dexmedetomidine in supraclavicular brachial plexus block and found it to delay the onset of sensory block, though it improved the postoperative analgesia .
In this study and as reported previously, addition of dexmedetomidine to LAs was not associated with significant higher risk of complications, such as bradycardia, hypotension, nausea and vomiting, or increased blood loss. Moreover, the mean blood loss in the studied groups did not vary from the range of previously published blood loss reports for external DCR under local anesthesia ,,.
Relatively low availability of research studies assessing the role of dexmedetomidine in LA in ophthalmic field as well as using a single dose of dexmedetomidine without evaluating different dose regimens are among the number of limitations of the study.
| Conclusion|| |
Addition of low-dose dexmedetomidine to LA infiltration for patients who presented for external DCR hastens the onset and prolongs the effective period of the sensory block. Enhancement of postoperative analgesia, increased perioperative sedation, and improved satisfaction of the patients were achieved without significant complications.
The authors acknowledge the staff members of Ibn Sina Eye Center, Tanta, Egypt, for their technical help and support.
The research was funded by the resources of Ophthalmology Department, Faculty of Medicine, Fayoum University.
Mohamed A Nassef made a contribution in design, definition of intellectual content of study, the collection of the data, manuscript editing, and manuscript review; Ahmed F. Gabr contributed in the design, in literature search, data acquisition, manuscript preparation, and manuscript editing, besides being the main surgeon; Sameh A. Ahmed participated in ensuring the intellectual content of the study, data analysis, statistical analysis, manuscript editing, and manuscript review, besides his role as the main anesthesiologist.
The manuscript has been read and approved by all the authors, the requirements for authorship have been met, and each author believes that the manuscript represents honest work.
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[Table 1], [Table 2]