Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 9  |  Issue : 2  |  Page : 207-211

Efficacy of dexmedetomidine as an anesthetic adjuvant for functional endoscopic sinus surgery under general anesthesia: A randomized-controlled study


1 Department of Anaesthesiology and Critical Care, Subharti Medical College, Swami Vivekanand University, Meerut, India
2 Department of Radiodiagnosis and Interventional Imaging, Subharti Medical College, Swami Vivekanand University, Meerut, India

Date of Submission05-May-2015
Date of Acceptance20-Oct-2015
Date of Web Publication11-May-2016

Correspondence Address:
Kumkum Gupta
108-109, Chanakyapuri, Shastri Nagar, Meerut - 250 004, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1687-7934.182259

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  Abstract 

Background
Functional endoscopic sinus surgery (FESS) requires effective control of bleeding for better visibility of the operating field and reduced risk of injury to the optic nerve or the internal carotid artery. Dexmedetomidine can provide controlled hypotension, analgesia, and sedation. The present study aimed to evaluate the clinical efficacy, safety, and advantages of dexmedetomidine as an anesthetic adjuvant for FESS.
Patients and methods
Fifty adult consented patients of comparable demographic profile, scheduled for FESS, were assigned randomly to two groups. Patients of group D received a loading dose of dexmedetomidine 1 mg/kg over 10 min, followed by an infusion at 0.4-0.7 mg/kg/h and patients of group C were administered an identical amount of saline solution. During the procedure, hemodynamic changes, intraoperative surgical grade of bleeding (on the basis of the Fromme-Boezaart scale), intraoperative fentanyl consumption, emergence time, and total recovery from anesthesia (Aldrete's score ≥9) were recorded.
Results
Patients of group D comparatively had a lower intraoperative heart rate and mean arterial blood pressure, along with a significantly lower bleeding score (P < 0.001). The mean intraoperative fentanyl consumption was significantly lower in patients of group D. Emergence time and time to achieve an Aldrete's score 9 or more were significantly lower in group C at 15 and 30 min postoperatively.
Conclusion
Dexmedetomidine has effectively provided the ideal oligemic surgical field during FESS and offers the inherent advantages of analgesia, sedation, and anesthetic-sparing effects.

Keywords: dexmedetomidine, functional endoscopic sinus surgery, oligemic surgical field


How to cite this article:
Gupta K, Gupta PK, Bhatia KS, Rastogi B, Pandey MN, Agarwal S. Efficacy of dexmedetomidine as an anesthetic adjuvant for functional endoscopic sinus surgery under general anesthesia: A randomized-controlled study. Ain-Shams J Anaesthesiol 2016;9:207-11

How to cite this URL:
Gupta K, Gupta PK, Bhatia KS, Rastogi B, Pandey MN, Agarwal S. Efficacy of dexmedetomidine as an anesthetic adjuvant for functional endoscopic sinus surgery under general anesthesia: A randomized-controlled study. Ain-Shams J Anaesthesiol [serial online] 2016 [cited 2021 Oct 23];9:207-11. Available from: http://www.asja.eg.net/text.asp?2016/9/2/207/182259


  Introduction Top


Functional endoscopic sinus surgery (FESS) is the treatment of choice for acute and chronic sinus pathologies and nasal polyp. This surgical intervention restores the drainage pathways and aeration of the paranasal sinus. There are many benefits of a well-performed endoscopic sinus surgery with appropriate indications, but major complications of orbital hematoma, injury to the optic nerve, cerebrospinal fluid fistula, and intracranial injuries could occur as bleeding reduces the visibility of the operative field. To minimize these complications, effective control of bleeding at the surgical site is required.

Various techniques to minimize bleeding during sinus surgery are head elevation of 30° (reverse Trendelenburg), infiltration or topical application of epinephrine, and electively controlled hypotension. Controlled hypotension is applied widely in several surgical interventions using different techniques [1].

Currently, many inhalational or intravenous anesthesia techniques, sympathetic antagonists, opioids, and direct-acting vasodilators are being evaluated to control intraoperative bleeding at the surgical site [2,3]. Although these pharmacological agents effectively lower the blood pressure, they are associated with delayed recovery from inhaled anesthetics, resistance to vasodilator or tachyphylaxis, and cyanide toxicity from nitroprusside. Esmolol and nitroglycerine precisely control the blood pressure because of their rapid onset and short duration of action, but unambiguous hemodynamic monitoring is required. An infusion of 10-20 mg/kg/h remifentanil is also useful, but is associated with the side effect of hyperalgesia [4,5]. Therefore, the choice of an ideal agent is still controversial.

Dexmedetomidine, a selective a2 agonist, is used as an adjuvant to general anesthesia for sedation, analgesia, and hemodynamic stability with no postoperative respiratory depression. It is valuable because of its analgesic and anesthetic-sparing effects [6].

The present study aimed to evaluate the clinical efficacy, safety, and advantages of dexmedetomidine, a highly selective a2-adrenoceptor agonist, in providing an ideal oligemic surgical field during FESS and sparing of analgesic and anesthetic agents.


  Patients and methods Top


After receiving approval from the Institution Ethical Committee and obtaining written informed consent, 50 adult patients of American Society of Anesthesiologists (ASA) physical status I and II of both sexes, aged 18-58 years, weighing 45-65 kg, scheduled for elective FESS were enrolled for this prospective double-blind randomized-controlled study. All patients were assessed clinically by chest radiography, ECG, and basal laboratory tests. Patients of ASA III and over, patients with a history of any cardiac or respiratory disease, hypertension, obesity (BMI >26 kg/m 2 ), hepatic or renal dysfunction, bleeding diathesis, abnormal prothrombin time, patients receiving b-blockers, sedatives, opioids, hypnotics, on cardiovascular medication, or those who had used NSAIDs within 7 days of surgery were excluded from the study. None of the patients had received general anesthesia previously.

Patients were divided into two equal comparable groups of 25 patients each by a computer-generated random number table. Patients of group D received a loading dose of dexmedetomidine 1 mg/kg over 10 min, followed by an infusion at 0.4-0.7 mg/kg/h and patients of group C were administered identical amounts of saline solution. In both groups, infusion was continued until 10 min from the end of the surgery. The study drug solution was prepared by an anesthesiologist who was blinded to the study protocol and was not involved in data collection. The anesthetic technique was standardized and FESS was performed by the same surgical team to ensure consistency in the estimation of the surgical field. The surgeon and resident anesthesiologist were also blinded to the treatment regimen.

Patients received lactated Ringer solution through an 18 G intravenous cannula and intramuscular glycopyrrolate (0.2 mg) was administered to all patients. On arrival to the operation theater, the baseline parameters of blood pressure, heart rate, oxygen saturation, temperature, and ECG were recorded and study drug infusion was started according to the randomization schedule. Patients were premedicated intravenously with ondansetron (4 mg), midazolam (2 mg), and fentanyl (2 mg/kg). After preoxygenation, anesthesia was induced with propofol 1.5-2 mg/kg supplemented if necessary by 0.2 mg/kg aliquots until loss of verbal command. Direct laryngoscopy and tracheal intubation with an adequate-sized cuffed endotracheal tube was facilitated with vecuronium bromide (0.1 mg/kg) and oropharyngeal packing was performed. Ventilation was mechanically controlled using a closed circuit with 60% nitrous oxide in oxygen to maintain end tidal carbon dioxide (EtCO 2 ) pressure at 32-36 mmHg and anesthesia was maintained with isoflurane. Cottonoids soaked with epinephrine 1 : 80 000 were inserted into nasal passages by the surgeon and the patients were placed in a 30° reverse Trendelenburg position.

Intraoperatively, the heart rate, blood pressure, ECG, EtCO 2 concentration, and peripheral pulse oximetry (SpO 2 ) were monitored and recorded at every 5 min intervals until the end of surgery. During the surgery, the infusion rate and dial concentration of isoflurane (0.8-1.5) were adjusted according to patient response to achieve a systolic blood pressure between 95 to 105 mmHg. Any additional fentanyl consumption was recorded. Bradycardia (heart rate<60 beats/min) was treated with intravenous atropine 0.5 mg.

During the procedure, the quality of the surgical field was assessed by the surgeon every 15 min with a predefined scale on the basis of Fromme-Boezaart scale: 0, no bleeding; 1, minimum bleeding and no suction required; 2, mild bleeding and occasional suction required; 3, moderate bleeding and frequent suction required; 4, severe bleeding and compromised surgical field and continuous suction required; 5, massive bleeding - dissection cannot be performed. The ideal category scale values for surgical conditions were predetermined to be 1 and 2 [5].

All infusions were discontinued 10 min before the end of surgery. When spontaneous breathing movements began, the residual neuromuscular blockade was reversed with neostigmine (2.5 mg) and glycopyrrolate (0.5 mg). Patients were extubated after observing adequate motor recovery and tidal volume during spontaneous breathing. Emergence time, defined as the interval between the discontinuation of anesthetics to response of eye opening to verbal command, was observed and recorded.

After full recovery, patients were transferred to the postanesthesia care unit and monitored for respiratory depression (respiratory rate <8 breaths/min), hemodynamic changes, nausea/vomiting, shivering, or any other drug-induced side effects. Postoperative recovery was evaluated using a modified Aldrete's score (0-10) and time needed to achieve 9 or more was recorded. Patients were also asked about recalling intraoperative events or any sign of awareness [7].

The sample size was based on initial pilot observations which indicated that approximately 20-22 patients had to be included in each group to detect a 20% decrease in bleeding in the dexmedetomidine group with a type 1 error of 0.05 and a power of 90%. Assuming a 5% dropout rate, the final sample size was set at 50 patients.

Statistical analysis

The recorded data are presented in a table format and expressed as mean ± SD or numbers of patients. Statistical analysis was carried out using Microsoft Excel and Stat Graphic Centurion 16 for windows (Statpoint Technologies Inc, Warrenton, Virginia). The demographic data for categorical variables were compared using the c2 -test. Statistical significance in time-related variables was analyzed using Student's t-test. A P value of less than 0.05 was considered statistically significant.


  Results Top


The present study was successfully completed on 50 adult consented patients and data of all patients were included for analysis. In this study, the efficacy of intravenous dexmedetomidine in reducing the bleeding during FESS was examined as well as its safety and advantages.

The demographic data of age, sex, weight, ASA physical status, and duration of surgery were comparable between the groups [Table 1]. The induction dose of propofol was significantly lower in group D than group C (1.67 ± 0.34 vs. 2.13 ± 0.49 mg/kg, respectively).
Table 1 Demographic characteristics of 50 patients

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Baseline values of the mean heart rate were comparable between the groups, but intraoperatively, there was a statistically significant reduction in the mean heart rate compared with the baseline value in group D (P < 0.05), with bradycardia (heart rate <60 beats/min) found in two patients, who promptly responded to intravenous atropine 0.5 mg. After extubation, the heart rate was found to be higher in patients of the control group (97.15 ± 12.17 vs. 87.4 ± 2.36 beats/min), but patients of group D did not show much variation in their mean heart rate values [Table 2].
Table 2 Changes in heart rate during anesthesia

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The baseline mean systolic blood pressure was comparable between the groups, but it was lower during surgery in patients of group D, with no statistically significant difference. No episode of hypotension was observed in any patient during the study period. After discontinuation of study drug infusion at the end of surgery and after recovery, blood pressure was significantly lower in group D (112.43 ± 15.7 vs. 133.37 ± 14.6 mmHg; P < 0.05). No reflex tachycardia was observed, but only one patient in group D experienced rebound hypertension [Table 3].
Table 3 Changes in systolic blood pressure during anesthesia

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The mean intraoperative fentanyl consumption in group D was significantly less compared with the control group (32.8 ± 3.2 vs. 65.3 ± 5.7 mg). Patients of group D needed less amount of isoflurane (dial concentration at 0.6-1) to maintain the systolic blood pressure compared with patients of group C, for whom dial concentration of isoflurane at 1-1.5 was necessary to maintain the desired level of blood pressure.

During FESS, surgeons experienced an ideal surgical site of grades 1 and 2 (minimum bleeding with sporadic suction) in 21 (84%) patients of group D, whereas no patients of the control group showed much reduction of bleeding at the surgical site despite a low systemic blood pressure. The difference in bleeding at the surgical site was statistically significant between the two groups [Table 4].
Table 4 Assessment of intraoperative bleeding (N = 50 patients)

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The emergence time (5.7 ± 1.63 vs. 8.7 ± 2.35 min) and time needed to achieve 9 or more of a modified Aldrete's score (8.9 ± 3.29 vs. 10.6±3.74 min) were significantly shorter in patients of the control group (P < 0.01) Respiratory rate and peripheral oxygen saturation (SpO 2 ) were comparable with no episode of desaturation at any time. No side effect of dexmedetomidine was observed during the study period.


  Discussion Top


The development of a nasal endoscope has facilitated the surgical treatment (FESS) of acute and chronic sinus pathologies when conservative treatment fails. The procedure perpetuates the mucociliary clearance mechanism and conserves the normal nonobstructing anatomic structures. However, major or minor complications could occur as bleeding reduces the visibility of the operative field and hampers the surgical intervention.

Previous studies showed that different opioids could achieve an oligemic surgical field, but the clearance of remifentanil was the most rapid, with side effects of nausea, vomiting, respiratory depression, pruritus, sinus bradycardia, and hypotension [4,5]. Preoperative steroid administration in cases of severe nasal polyposis improves visibility because of its anti-inflammatory and antiedematous effect [8]. Topical vasoconstrictors are applied to decrease mucosal congestion and bleeding, but hypertension and tachycardia may occur. Controlled hypotension is commonly used nowadays to achieve a bloodless operative field.

Premedication with intravenous dexmedetomidine before induction of anesthesia has significantly decreased the heart rate, blood pressure, and bleeding at the surgical site, which is attributed to the known sympatholytic effects of a2-adrenergic agonists. They regulate the autonomic and cardiovascular systems by acting on blood vessels, where they mediate vasoconstriction, and on sympathetic terminals, it attenuates the heart rate and blood pressure by inhibiting norepinephrine release [6].

The efficacy of dexmedetomidine in providing an ideal surgical field during controlled hypotension has been reported previously during middle ear and maxillofacial surgery. Its hemodynamic effects are predictable and dose dependent. Many studies have investigated the effects of dexmedetomidine before induction of anesthesia and reported a significant reduction in heart rate and blood pressure [9,10].

The optimal anesthetic technique seems to be relative bradycardia with associated hypotension. Ulger et al. [11] compared dexmedetomidine with nitroglycerin to achieve controlled hypotension in patients scheduled for middle ear surgeries. The infusion rate of drugs was titrated to maintain a mean arterial pressure between 65 and 75 mmHg. They concluded that dexmedetomidine was better in maintaining hemodynamic stability and a drier surgical field, and did not cause reflex tachycardia or rebound hypertension [11]. In the present study, there was no need to increase the infusion rate of dexmedetomidine as it was sufficient to achieve a moderately controlled hypotension. No reflex tachycardia was observed, but only one patient experienced rebound hypertension.

Guven et al. [12] and Goksu et al. [13] reported better hemodynamic stability, visual analog scale for pain, clear surgical field, and few side effects when dexmedetomidine was administered for FESS. In the present study, the efficacy of dexmedetomidine in reducing the bleeding of the surgical site was examined. There was a significant improvement in the quality of the surgical field and an ideal surgical field was achieved in 86% of patients of group D with little bleeding that did not hamper the surgical procedure.

Dexmedetomidine exerts sedative and analgesic sparing effects through central actions in the locus coeruleus and in the dorsal horn of the spinal cord. In the present study, the induction dose of propofol was significantly lower in patients of group D, which is in agreement with the results of other workers who reported that dexmedetomidine caused a reduction in the overall dose of propofol required to produce loss of consciousness and verbal command [14].

Dexmedetomidine provided analgesia through binding in the spinal cord. In the present study, intraoperative fentanyl consumption was significantly less in group D compared with the control group. Several other studies also concluded that perioperative use of dexmedetomidine is associated with a significant decrease in the consumption of inhalational agents and analgesia in a dose-dependent manner [9,10]. We used isoflurane as the main anesthetic agent and its requirement was also reduced to maintain the anesthetic depth. Synergism between isoflurane and dexmedetomidine was observed in our study.

Coughing on the tracheal tube during awakening will increase venous pressure and may cause postoperative bleeding; thus, deep extubation with smooth recovery is preferable. Guler et al. [15] found that the increase in blood pressure and heart rate during extubation is decreased and the quality of extubation is improved by dexmedetomidine.

Dexmedetomidine was associated with significantly longer emergence time and time to total recovery from anesthesia. Richa et al. [16] reported a significantly slower extubation time in patients receiving dexmedetomidine compared with those receiving remifentanil for controlled hypotension. In the present study, patients of the dexmedetomidine group had slower but smooth emergence from anesthesia compared with the control group [17].


  Conclusion Top


Dexmedetomidine with isoflurane was effective and safe to provide an oligemic surgical field during FESS. It offered many inherent advantages of analgesia, sedation, and anesthetic-sparing effect. However, dexmedetomidine was associated with longer but smoother recovery time from anesthesia.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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    Tables

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


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