|Year : 2014 | Volume
| Issue : 2 | Page : 70-74
Dexmedetomidine and propofol for monitored anesthesia care in the middle ear surgery
Reetu Verma1, Rajni Gupta1, VK Bhatia1, Jaishri Bogra1, SP Agarwal2
1 Department of Anaesthesiology and Critical Care, King George's Medical University, Lucknow, Uttar Pradesh, India
2 Department of ENT and Head and Neck Surgery, King George's Medical University, Lucknow, Uttar Pradesh, India
|Date of Web Publication||3-May-2014|
Department of Anaesthesiology and Critical Care, King George's Medical University, Lucknow, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Context: Local anaesthesia with sedation is a well established approach used for tympanoplasty. Dexmedetomidine is a new drug which acts on α2-adrenergic receptors in the dorsal horn of the spinal cord to produce analgesic effects. Aims: Efficacy and safety of intravenous dexmedetomidine in comparison to propofol. Setting and Design: Randomized controlled trial. Materials and Methods: Eighty patients were randomly allocated to receive either dexmedetomidine or propofol as intravenous bolus followed by the same in infusion supplemented with local anaesthesia for tympanoplasty. Statistical Analyses Used: Statistical Package for Social Sciences version 15.0. Results: Dexmedetomidine and propofol provides adequate sedation but the use of propofol is associated with more requirements of rescue analgesia and poor patient and surgeon satisfaction. Conclusion: These results suggest that dexmedetomidine provides adequate sedation with analgesia and good surgical and patient comfort without any adverse effects for patients undergoing tympanoplasty under local anaesthesia
Keywords: Dexmedetomidine, Propofol, Sedation, Surgery
|How to cite this article:|
Verma R, Gupta R, Bhatia V K, Bogra J, Agarwal S P. Dexmedetomidine and propofol for monitored anesthesia care in the middle ear surgery. Indian J Otol 2014;20:70-4
|How to cite this URL:|
Verma R, Gupta R, Bhatia V K, Bogra J, Agarwal S P. Dexmedetomidine and propofol for monitored anesthesia care in the middle ear surgery. Indian J Otol [serial online] 2014 [cited 2019 Apr 20];20:70-4. Available from: http://www.indianjotol.org/text.asp?2014/20/2/70/131872
| Introduction|| |
Tympanoplasty can be done both under local or general anesthesia. Some surgeons prefer using local anesthesia for middle ear surgery owing to various advantages such as less bleeding and being able to test hearing during the surgery itself. However, local anesthesia alone has been reported to be associated with anxiety, dizziness, claustrophobia, and earache; , hence, there is always a quest to find out an anesthetic drug, which can be used with local anesthetic block with maximum benefit and with minimum associated disadvantages. A variety of drugs are being used viz., propofol, benzodiazepines and opioids have been used for hypnosis, sedation and analgesia in the middle ear surgery in order to enhance the patient and surgical comfort; , however, none has been completely complication free. Among various complications reported are - over-sedation, respiratory depression, disorientation and hampered patient's cooperation during surgery. 
Dexmedetomidine (dexM), is a centrally acting α-2 receptor agonist with analgesic and conscious sedative effect without respiratory depression. It has been reported to significantly reduce the opioid requirements both during and after surgery. ,, In addition, dexM has a sympatholytic effect that can attenuate the stress response to surgery (tachycardia and hypertension) and maintains hemodynamic stability. , In the present study, we have compared dexM with propofol. Propofol is a widely used sedative-hypnotic with a rapid onset of action, short recovery time along with antiemetic and euphoric properties. 
Thus, the present study was planned to evaluate the efficacy of dexM as analgesic, sedative with its hemodynamic effects among patients undergoing tympanoplasty under monitored anesthesia care. Patient satisfaction, surgeon satisfaction and side-effects were the secondary outcome.
We have used propofol as another drug for the comparison because it is the drug, which is widely used for monitored anesthesia care.
| Materials and Methods|| |
After obtaining approval from Institutional Committee and informed patient consent, 80 American Society of Anesthesiologists (ASA) I-II patients, aged 18-60 years, who were planned for tympanoplasty under local anesthesia were enrolled in the study. Those having severe cardiac disease, 2 nd or 3 rd degree heart block, chronic obstructive lung disease, renal and hepatic insufficiency, endocrine, metabolic or central nervous system disorders, pregnant and lactating female, any drug allergy, α-2-agonist or antagonist therapy taken, and active upper respiratory infection, were excluded from the study. Routine monitoring was performed with electrocardiogram, SPO 2 and noninvasive blood pressure monitoring. Intraoperatively, all the patients received 2 L/min oxygen via nasal catheters. All the patients were premedicated with injection glycopyrrolate. 2 mg and injection fentanyl 1 μg/kg. The patients were randomly allocated into two groups.
Group A: Was the dexM group. They received a loading dose of 1 μg/kg (infusion was given over 10 min) and an infusion was continued during the operation at a rate of 0.4 μg/kg/h (dexM was diluted in 0.9% normal saline to a concentration of 4 μg/ml in 50 ml syringe).
Group B: Was the propofol group. They received a loading dose of injection propofol 75 μg/kg/min intravenously (i.v.) (infusion was given over 10 min), and an infusion was continued during the operation at the rate of 50 μg/kg/min.
Dexmedetomidine or propofol was prepared by one of the authors and administered by using a syringe infusion pump.
After achieving a Ramsay sedation score of 3, operative field was infiltrated with lignocaine 2% and 1/100,000 epinephrine (2:1 v/v) and the surgery was started. Patient's response to local anesthetic infiltration was evaluated for pain and body movement. Pain was recorded on 10-point verbal scale where, 0 indicated no discomfort and 10 indicated maximum discomfort). A rescue bolus of fentanyl 1 μg/kg was given to all those patients responding with the pain score >4 or showing movement during infiltration.
All the patients were under monitored anesthesia care for hemodynamic parameters. Sedation scores were noted using Ramsay sedation scale (RSS) [Table 1]. Analgesia level was recorded using visual analog scale on a scale of 0-10 (0 = no pain, 10 = worst pain). All these parameters were recorded intraoperatively as well as postoperatively. Per operative parameters viz., mean arterial pressure (MAP), heart rate (HR) and peripheral oxygen saturation (SPO 2 ) were recorded at 5 min intervals for the first 15 min and after that at every 15 min interval. During the procedure, study drug infusion rate was varied to maintain a deep level of sedation (RSS of 3, tested at 5-10 min intervals) and normal cardiovascular and respiratory variables (i.e., respiratory rate >12 breaths/min, SpO 2 >94%). Sedation was stopped if the respiratory rate was less than 12 bpm or SPO 2 <94%. If a patient was not adequately sedated through drug titration and complained pain, rescue injection fentanyl 1 μg/kg was given. If any of the patient required more than a single dose of rescue analgesic he/she was excluded from the study. MAP <60 mm of Hg was considered as unwanted hypotension and supplemented with fluid boluses. If the patient did not respond to this then injection mephentermine 6 mg was given, and infusion rate was reduced to half. HR <50 bpm was considered as bradycardia and infusion rate was reduced to half and injection atropine 0.5 mg was given and as per requirement.
The study drug was stopped at the end of surgery and patients were shifted to post anesthesia care unit (PACU). Subjects remained in the PACU at least for 1 h and discharged to postoperative ward ensuring that the patient had achieved an Aldrete score of 10. Vital signs were recorded every 5 min for the first 15 min, then every 15 min while the patient remained in PACU. The RSS and pain scores were assessed every 15 min while the patient was in the PACU. Just before the discharge from PACU, patients were asked to rate their satisfaction with sedation on seven-point Likert like verbal rating scale [Figure 1] and pain on a visual analog scale that was explained to patient on the preoperative visit. Surgeon satisfaction was also recorded postoperatively as he was also asked to rate their experience with comfort during operation using a seven-point Likert like verbal rating scale.
|Figure 1: Seven-point Likert like verbal rating scale for patient or surgeon satisfaction|
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Adverse events were noted as nausea, vomiting, dry mouth, hypotension (MAP <60 mmHg), bradycardia (HR <50 bpm), and hypoventilation (SPO 2 <94%).
Data were analyzed using Statistical Package for Social Sciences version 15.0 (Themis and Neon). Independent sample's t-test was used to compare the parametric data, whereas categorical data were compared using Chi-square test. Fisher exact test was used wherever, the expected frequency of a cell was <5. Confidence level of the study was kept at 95%; hence a P < 0.05 indicated a statistically significant association.
| Results|| |
As in propofol group, 3 patients required more than a single dose of rescue analgesic and in dexM group for 1 patient surgery time was more than 1 h and hence these 4 patients were excluded from the study. So at the end data were available for 76 patients.
The two groups were matched for age, sex, body weight, ASA grade, and duration of surgery [Table 2].
Time to achieve adequate RSS was 9.5 ± 1.4 min in P group, whereas in D group, it was 14.5 ± 1.7 min thus showing a significant difference between two groups (P < 0.001).
Group D had significantly lower incidence of local anaesthesia injection pain and significantly longer time till demand of rescue analgesic as compared to Group P (P = 0.002). A total of 15 (37.5%) patients in P group could not be sedated using specified protocol as they complained of pain and had to be supplemented with injection fentanyl. However, in D group only 4 (10%) patients required injection fentanyl thus showing a significant difference between two groups (P = 0.008). Both patient satisfaction and surgeon satisfaction were significantly better in D group when compared to P group (P < 0.001) [Table 3].
Mean arterial pressure and HR values during sedation and recovery were significantly lower than those at baseline in both groups [Figure 2] and [Figure 3], but intraoperative MAP (P < 0.001) was significantly lower in P group as compared to D group. A total of 10 (20%) patient in P group and 2 (5%) in D group developed hypotension (MAP < 60 mm Hg), which was managed by either giving fluid or injection mephentrimine. Two patients in dexM group had bradycardia and these patients were successfully treated with 0.5 mg i.v., atropine. Respiratory rate (>12/min) and SPO 2 (>94%) were maintained in both the groups with no incidence of respiratory depression in either of the two groups. A total of 8 (20%) patients in D group and 5 (12.5%) patient in group P complained of dry mouth in the postoperative period. Statistically, a significant difference between two groups was observed only for episodes of hypotension (P = 0.025) [Table 4].
| Discussion|| |
There have been several reports on the successful use of dexM as the primary sedative drug for orthopedic, ophthalmic, dental, and plastic surgery, and for diagnostic procedures. Due to its analgesic properties, cooperative sedation and lack of respiratory depression, dexM is increasingly being used as a sedative for monitored anesthesia care. ,,
In the present study, we have demonstrated that both dexM and propofol provide adequate levels of sedation without clinically significant respiratory depression in the perioperative period, but use of propofol is associated with increased requirement of intraoperative rescue analgesic and increased hemodynamic instability (hypotension).
We compared the dexM with propofol infusion because propofol is the drug that has been used commonly in past for monitored anaesthesia care. However use of propofol has been associated with local anesthetic injection pain, more incidence of breakthrough pain, patient discomfort or patient movement. , We, also observed the same that patient in propofol group had more incidence of local anesthetic injection pain.
Patients in the dexM group had lower pain scores as well as reduced requirement of rescue analgesic intraoperatively and postoperatively, which is consistent with the findings of Arain and Ebert  We also observed that more patients in P group required injection fentanyl as rescue analgesic in comparison to D group that explains the analgesic property of dexM.
As dexM inhibits the central sympathetic outflow and inhibits the norepinephrine release by stimulation of α-2 adrenoceptor, , it is expected to decrease MAP as observed by Kaygusuz et al.  and Ghali et al.  in their studies. However, we observed that patients receiving propofol had significantly decreased levels of MAP as same observed by Arain and Ebert  This may be due to the powerful inhibitory effect of propofol on sympathetic outflow. 
We also observed that, two patients in dexM group developed bradycardia, which were successfully managed with injection atropine. An increase in vagal activity may also be involved in the hemodynamic effects of dexM. 
Both surgeon comfort and patient satisfaction regarding sedation was more in D group. But Ghali et al.  observed in their study that surgeon satisfaction was equal for both groups as they compared the dexM with propofol for vitreoretinal surgery under subtenon's anesthesia and the reason may be the different type of surgery.
Dry mouth is a known side effect of α-2 agonist. We also observed that more patients (20%) in D group complained of dry mouth postoperatively as compared to those in P group (12.5%) but this difference was not significant statistically. This may be because of use of glycopyrrolate injection in pre medication.
| Conclusion|| |
On the basis of the findings of the present study, dexM seems to be a better drug for monitored anesthesia care with minimal hemodynamic instability when compared to propofol.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]