|Year : 2021 | Volume
| Issue : 4 | Page : 368-374
Efficacy of dexmedetomidine versus propofol in patients undergoing endoscopic transnasal transsphenoidal pituitary tumor resection
Maha Younis Youssef Abdallah1, Yasser Wafik Khafagy2, Mohamed Younes Yousef AbdAllah1
1 Department of Anesthesia and Surgical Intensive Care, Faculty of Medicine, Mansoura University, Mansoura, Egypt
2 Department of ENT, Faculty of Medicine, Mansoura University, Mansoura, Egypt
|Date of Submission||12-Dec-2021|
|Date of Acceptance||26-Jan-2022|
|Date of Web Publication||01-Mar-2022|
Dr. Maha Younis Youssef Abdallah
Departments of Anesthesia and Surgical Intensive Care, Faculty of Medicine, Mansoura University, Mansoura
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Dexmedetomidine is associated with good perioperative hemodynamics together with decreased opioid requirements. Furthermore, propofol has been used to achieve hypotensive anesthesia as a part of total intravenous anesthesia. Aims: This study was performed to compare dexmedetomidine and propofol on the adequacy of hypotensive anesthesia during transsphenoidal resection of pituitary tumors. Patients and Methods: A total of 110 cases were included in this prospective randomized study. They were randomized into two equal groups; Group D commenced on Dexmedetomidine, and Group P, which received propofol. Comparing intraoperative hemodynamic parameters and the Boezaart Bleeding Scale was our primary outcome. The secondary outcomes included isoflurane and propranolol consumption, recovery, postoperative analgesic profile. Statistical Analysis: IBM's SPSS Statistics (Statistical Package for the Social Sciences) for Windows (version 25, 2017) was used for the statistical analysis of the collected data. Shapiro–Wilk test was used to check the normality of the data distribution. The quantitative variables were expressed as mean and standard deviation, whereas the categorical variables were expressed as frequency and percentage. Independent sample t and Mann − Whitney tests were used for the comparison of parametric and nonparametric continuous data, respectively. For pair-wise comparison of data (within-subjects), the follow-up values were compared to their corresponding basal value using the paired samples t-test or Wilcoxon matched-pairs signed-ranks test. Fisher exact and Chi-square tests were used for inter-group comparison of nominal data using the crosstabs function. Results: Age, gender, body mass index, and systemic comorbidities did not significantly differ between the two groups. Furthermore, heart rate and blood pressure were comparable at baseline, during operation, and after extubation. Boezaart score, blood loss, isoflurane, and propranolol consumption were also comparable between the two groups. Group D expressed significantly longer emergence and extubation times than Group P. Nevertheless, cases in the same group expressed lower Visual Analog Scale values and postoperative analgesic requirements. Conclusion: Although Dexmedetomidine and propofol are associated with comparable intraoperative hemodynamic changes, the former drug appears to be superior regarding pain control, postoperative analgesic requirement.
Keywords: Dexmedetomidine, hypotensive anesthesia, pituitary surgery, propofol
|How to cite this article:|
Abdallah MY, Khafagy YW, AbdAllah MY. Efficacy of dexmedetomidine versus propofol in patients undergoing endoscopic transnasal transsphenoidal pituitary tumor resection. Anesth Essays Res 2021;15:368-74
|How to cite this URL:|
Abdallah MY, Khafagy YW, AbdAllah MY. Efficacy of dexmedetomidine versus propofol in patients undergoing endoscopic transnasal transsphenoidal pituitary tumor resection. Anesth Essays Res [serial online] 2021 [cited 2022 Nov 29];15:368-74. Available from: https://www.aeronline.org/text.asp?2021/15/4/368/338927
| Introduction|| |
Neuroanesthesia has some basic principles, including smooth induction, hemodynamic stability, maintaining cerebral perfusion and providing optimal operative conditions to facilitate good exposure for the surgeon. Smooth emergence is also as important as smooth induction as it allows the early assessment of the neurological functions after surgery.
Transsphenoidal resection of pituitary tumors is a common neurosurgical procedure, as it accounts for 20% of all intracranial operations in most neurosurgical centers. Anesthetic management for such cases represents a challenge to anesthesiologists as nasal speculum insertion during the procedure results in a strong nociceptive stimulation, leading to tachycardia and hypertension. This will lead to bleeding and difficult visualization of the operative field.,
Multiple drugs have been recommended to achieve controlled hypotension during neurosurgical procedures, including beta-blockers, sodium nitroprusside, nitroglycerine, increasing the doses of inhaled anesthetics, alpha-2 agonists, and magnesium sulfate.,,
Propofol, a widely used intravenous anesthetic agent, has been used to achieve hypotensive anesthesia due to its potent hypotensive action. Its short-term infusion is safe, and normal blood pressure is rapidly restored after its discontinuation.
Dexmedetomidine is a selective alpha-2 adrenergic receptor agonist that has sedative, analgesic, and anesthetic sparing effects without any negative impact on the respiratory center. It modulates pain signals transmission through acting on both spinal and supraspinal regions. It is also associated with decrease inhaled anesthetic requirements. In addition, in neurosurgical patients, it helps to stabilize intracranial pressure along with intraoperative hemodynamic stability, especially on intubation and extubation. It also allows earlier awakening due to decreased anesthetic and opioid consumption.,
According to our knowledge, there is a paucity of studies comparing the effects of dexmedetomidine and propofol on the adequacy of hypotensive anesthesia during transsphenoidal resection of pituitary tumors. Thus, we conducted the current study aiming to compare these two drugs on the adequacy of hypotensive anesthesia during transsphenoidal resection of pituitary tumors.
| Patients and Methods|| |
This is a prospective randomized study that was conducted at Mansoura University hospitals during the period of 2 years, starting from December 2019 to December 2021. The study was designed for adult cases aged between 18 and 65 years who were electively prepared for pituitary tumor resection. On the other hand, patients with Glasgow Coma Scale <15, American Society of Anesthesiologists physical status class score >II, preoperative hear rate <50 bpm, first- or second-degree heart block, allergy to the study medications, and pregnancy were excluded. In addition, patients commenced on beta-blockers, alpha-methyl dopa, clonidine, or other alpha-2 agonists were excluded.
The sample size was computed based on a previous study, where at the time of nasal speculum insertion, the increase in mean arterial pressure (MAP) was 9.4% in the Dexmedetomidine group, on G power to detect a difference of 20% in MAP between the propofol group and the dexmedetomidine group. The required sample size for α error of 0.05 and power of 80% was estimated to be 55 patients per group.
Before surgery, informed written consent was obtained from all of the participants after a detailed explanation of the details of the surgical procedure, pros and cons of each medication. Furthermore, the study gained approval from the Institutional Review Board of the faculty of medicine, Mansoura University with reference number R.21.09.1454 at November 20, 2021.
The included 110 cases were randomly allocated using a computer-generated randomization table into two equal groups; Group D, which included 55 cases which were commenced on dexmedetomidine (1 mcg. kg−1 over 10 min followed by a maintenance of 0.5 mcg. kg−1.h−1), and Group P which included the remaining 55 cases who received propofol (150 μg.kg−1.h−1 initially which was titrated to maintain MAP between 55 and 65 mmHg with stable hemodynamics). Both drugs were prepared by a staff nurse in an opaque syringe and an anesthesiologist who were blind to both drug and patient allocation.
On arrival at the neurosurgical operative theater, the standard patient monitoring was ensured, including noninvasive arterial pressure, pulse and oxygen saturation. In addition, an intravenous line was established. Before induction, midazolam (0.03 mg.kg−1) was given in all cases. Induction of anesthesia was done by propofol (0.5–2 mg.kg−1), whereas atracurium (0.5 mg.kg−1) was used for neuromuscular blockade. Then, direct laryngoscopy with insertion of the appropriate size endotracheal tube was done.
Anesthesia was maintained with air in oxygen (50%:50%) and isoflurane. Intermittent positive pressure ventilation with a tidal volume of 7–8 mL. kg body weight was done to maintain end-tidal carbon dioxide between 30 and 35 mm Hg. Furthermore, a moist cotton gauze was used to pack the posterior pharynx under direct laryngoscopy.
If any rise in the heart rate or mean blood pressure >20%, compared to the baseline, the initial isoflurane 0.5% end-tidal concentration was increased by 0.2% every 4 min up to a maximum of 2% end-tidal concentration. If no response was detected, either nitroglycerine (increment 0.1–0.25 mg) or propranolol (increment 0.5 up to 2 mg) was administered.
Both blood pressure and pulse were measured and monitored. It has been recorded at the following time points; baseline, before intubation, after intubation, insertion of a nasal speculum, at 15 min, 30 min, then after 30 min till the end of the surgery, preextubation, and postextubation.
Suppose hypotension was detected, defined as systolic blood pressure <90 mmHg, ephedrine 5 mg was given intravenously. Besides, bradycardia, defined as heart rate <50 bpm, was managed by intravenous atropine (0.02 mg.kg−1).
Boezaart Bleeding Scale was used to evaluate the quality of surgical field regarding blood loss as follows; (0) virtually bloodless field, (1) slight oozing for which suctioning is not essential, (2) mild bleeding requiring occasional suctioning without interference with the surgical field, (3) moderate bleeding requiring usual suctioning that improves the visual field, (4) heavy bleeding with frequent suctioning, and the surgical field worsens after suction is removed, (5) severe uncontrollable bleeding faster than suctioning.
Blood loss, fluid intake, and urine output were measured and recorded. Both propofol and dexmedetomidine were discontinued 10 min before the end of the surgery, which was defined as the time point when the neurosurgeon removed the nasal speculum. After that, isoflurane was ceased, and neuromuscular blockade was reversed by neostigmine and atropine. The total doses of isoflurane, propranolol, and nitroglycerine were calculated and recorded. The total isoflurane dose was calculated as recommended by Biro.
In addition, both emergence and extubation times were recorded. Emergence time was defined as the time interval between isoflurane discontinuation and time to spontaneous eye opening in response to a verbal command. Extubation time was defined as the time interval between isoflurane and extubation.
All patients were then moved to the neurosurgery intensive care unit (ICU), where observation was continued by an investigator and an ICU nurse, neither of whom was aware of the anesthetic regimen. Postoperative pain was evaluated by the Visual Analog Scale (VAS), with 0 for no pain and 10 for the worst pain ever.
Comparing intraoperative hemodynamic parameters along with the Boezaart Bleeding Scale were our primary outcomes. The secondary outcomes included inhalational anesthetic requirement, hypotensive agent doses required, emergence time, extubation time, postoperative pain, and analgesic requirements.
IBM's Statistical Package for the Social Sciences (SPSS) statistics for Windows (version 25, 2017) (IBM corporation, Armonk, NY, USA) was used for the statistical analysis of the collected data. Shapiro–Wilk test was used to check the normality of the data distribution. Quantitative variables were expressed as mean and standard deviation, whereas categorical variables were expressed as frequency and percentage. Independent sample T and Mann − Whitney tests were used for the comparison of parametric and nonparametric continuous data, respectively. For pair-wise comparison of data (within-subjects), the follow-up values were compared to their corresponding basal value using the paired samples t-test or Wilcoxon matched-pairs signed-ranks test. Fisher exact and Chi-square tests were used for inter-group comparison of nominal data using the crosstabs function.
| Results|| |
Both age and gender were not significantly different between the two groups (P = 0.640 and 0.565 respectively). The mean age of the included cases was 46.62 and 45.75 years in groups D and P, respectively. Males represented 58.2 and 52.7% of the included population in both groups, respectively. In addition, the mean values of body mass index were 30.1 and 29.77 kg.m2 in the study groups, respectively (P = 0.693). Diabetes mellitus was present in 3.6% and 9.1% of cases, whereas hypertension was prevalent in 20% and 18.2% of cases in the same groups, respectively. Operative time did not significantly differ between the study groups (160.91 and 153 min, respectively, – P = 0.155). [Table 1] illustrates these data.
|Table 1: Demographic characteristics, medical history and operative duration of the study groups|
Click here to view
Basal, intraoperative, and postextubation heart rate measurements were statistically comparable between the two groups (P > 0.05). These data are illustrated in [Table 2].
|Table 2: Basal and follow-up values of the study groups' heart rate (beat/min)|
Click here to view
Mean arterial blood pressure values did not significantly differ between the two groups at baseline or during drug infusion. [Table 3] illustrates these data.
|Table 3: Basal and follow-up values of mean arterial pressure (mmHg) of the study groups|
Click here to view
The mean values of Boezaart score were significantly lower in Group D than Group P (1.43 vs. 1.57 respectively– P = 0.033). In addition, propranolol consumption showed a significant decrease in Group D (P < 0.001). Nevertheless, isoflurane consumption and blood loss showed no significant difference when comparing the same groups. Furthermore, neither intraoperative fluid intake nor urine output was significantly different between the two groups (P = 0.616 and 0.225, respectively).
In addition, Group D expressed significantly longer emergence and extubation times than Group P. However, cases in the same group expressed significantly higher VAS values (P = 0.018) and a higher postoperative analgesic requirement (P = 0.04). [Table 4] summarizes these data.
|Table 4: Intra-operative isoflurane, propranolol and nitroglycerine consumption, Boezaart score, fluid intake, urine output, blood loss, emergence and extubation times, postoperative Visual Analog Scale score and morphine requirements of the study groups|
Click here to view
| Discussion|| |
As earlier clinical investigations have pointed to the efficacy of Dexmedetomidine as a sedative in critically ill patients, newer studies have focused on the efficacy of alpha-2 receptor agonists as adjuvants to neuroanesthesia. Dexmedetomidine has multiple favorable clinical effects, including hemodynamic stability, neuroprotection, lack of respiratory depression without interference with intraoperative neurophysiological monitoring. These pros suggest that dexmedetomidine could be useful in the management of neurosurgical patients.
The current study was conducted at Mansoura University Hospitals, aiming to compare Dexmedetomidine and propofol on the adequacy of hypotensive anesthesia during transsphenoidal resection of pituitary tumors. A total of 110 cases was included, and they were divided into two groups; Group D (55 cases), which was commenced on Dexmedetomidine, and Group P (55 cases), which received Propofol.
No significant differences were detected between the two study groups as regard demographic characteristics, and that should nullify any bias that may have skewed results in favor of one group rather than the other one. Moshiri et al. also conducted a study in 2017, which handled the same perspective as ours, but in endoscopic sinus surgeries, reported no significant difference between the two groups regarding most of the preoperative data, which confirms our findings.
In the current study, both groups expressed comparable heart rate and blood pressure findings at baseline, during operation or after extubation. Similarly, Godbole et al., reported almost no significant difference between propofol and Dexmedetomidine regarding heart rate or blood pressure. Their study compared the same pharmacological agents regarding maintaining hypotensive anesthesia during ENT surgeries. Another study stated that both drugs were successful in maintaining hypotension. However, more reduction of heart rate was encountered in the propofol group.
Cardiovascular response in the form of tachycardia and hypertension is frequently encountered in multiple intracranial surgical procedures. About 50%–90% of such cases require perioperative antihypertensive agents to control blood pressure., Due to severe nociceptive stimuli experienced by the patients during transsphenoidal pituitary surgeries, the anesthesiologist often encounters perturbations in heart rate and blood pressure during multiple surgical stages. This will require increasing the depth of anesthesia or increasing opioid administration, leading to hypotension with a compromise of the cerebral circulation. Besides, these maneuvers are associated with prolonged recovery time.,
In intragroup comparison, one should notice the significant decrease in the MAP and heart rates during operation compared to the baseline. In line with our findings, Bala et al. reported that dexmedetomidine administration was associated with a significant decrease in mean arterial blood pressure and heart rate compared to controls despite being comparable at baseline. Batra et al. also reported that both heart rate and blood pressure readings had lower values in the dexmedetomidine group than controls throughout most intraoperative readings. However, both groups had no significant difference before operation. Moreover, other studies have confirmed our findings regarding the effectiveness of dexmedetomidine in maintaining hemodynamic stability in pituitary surgeries.,
Multiple previous studies have confirmed the efficacy of dexmedetomidine in attenuating the changes in intraoperative hemodynamics. Therefore, it gained great popularity in neurosurgical procedures.,, Its central and peripheral actions could explain these effects. In the central nervous system, it decreases the sympathetic outflow. In addition, it blocks peripheral ganglia. The previous mechanisms could explain its protective effect on hemodynamic changes during neurosurgical procedures.
The previous reports emphasize the importance of dexmedetomidine as adjunctive to general anesthesia in such cases, as it decreases the occurrence of hypertensive episodes, which can lead to bleeding, edema, worsened surgical field, and increased intracranial pressure.
When it comes to propofol and its effects on hemodynamics in the current study, it had similar effects to dexmedetomidine. Propofol is also known to induce bradycardia in humans due to sympathetic inhibition. It also induces hypotension through decreasing cardiac output and systemic vascular resistance. This drug has a unique advantage; when the heart rate increases due to blood pressure decrease, it is decreased through suppression of the baroreceptor reflex. The previous facts are in line with our findings.
In the current study, the mean values of the Boezaart score were comparable between the two groups. These effects are secondary to better hypotensive anesthesia with both agents, leading to decreased tissue oozing during surgical dissection, especially in narrow surgical fields like those encountered in neurosurgical practice.
Multiple studies have documented that better surgical field visibility is directly related to hypotensive anesthesia and heart rate., As both agents had comparable heart rates and MAP during operation, we expected to find comparable results regarding surgical field quality. This was also evident in our study's blood loss, which was comparable between the two groups.
Similar to our findings, Moshiri et al. et al. reported no significant difference between the two groups regarding bleeding score (P = 0.490), which had mean values of 1.14 and 1.24 in the Dexmedetomidine and propofol groups, respectively.
Moreover, other authors confirmed the efficacy of propofol infusion in improving the quality of the surgical field through deliberate hypotension. However, this study was conducted on patients undergoing endoscopic sinus surgery.
In our study, Group D had comparable isoflurane consumption between the two study groups. Dexmedetomidine is associated with decreased inhalation anesthetic requirement because of its α-2 agonist actions, which inhibit noradrenergic transmission., Its sedative effect is associated with a 35%–50% reduction in intraoperative isoflurane requirements. This was documented in three previous studies that reported that dexmedetomidine administration led to decreased inhalation anesthetic intake.,, Of course, this will lead to a faster and better recovery from anesthesia, allowing early assessment of the patient's neurological functions after the operation.
In the current study, propranolol administration was comparable between the two study groups. This is secondary to the obtained heart rate and blood pressure measurements during surgery. It was comparable between the two groups, which led to a more or less similar propranolol dose between the two groups.
Our findings revealed that Group P expressed significantly shorter emergence and extubation times than Group D. Both early emergence and tracheal extubation are crucial for neurosurgical anesthesia. Similarly, Gunes et al. noted delayed recovery after intracranial surgery in patients administered dexmedetomidine.
Moshiri et al. reported comparable recovery time between both agents (P = 0.166), which had mean values of 32.52 and 29.9 min in the dexmedetomidine and propofol groups, respectively.
On the contrary, Tanskanen et al. and Ilhan et al. also noted that the dexmedetomidine infusion was associated with faster recovery from general anesthesia. They also reported no cases with respiratory depression that may delay patient recovery.,
When it comes to postoperative pain, Group D expressed significantly lower VAS values and lower postoperative analgesic requirements. In the same context, a previous study has reported that the analgesic effects of dexmedetomidine are not negligible, as it was associated with a significant decrease in the perioperative opioid consumption in cases undergoing minor surgeries. This analgesic effect is mediated through alpha-2 receptors located at the spinal cord and the supraspinal and peripheral sites. This, in turn, will impact postoperative analgesic consumption, which showed a significant decrease in the same group.
All in all, one should notice the comparable intraoperative effects of both drugs. Dexmedetomidine had the upper hand on the postoperative analgesic profile, while propofol showed its superiority in the recovery profile. Another point that should be considered is that propofol needs frequent change in the rate of infusion according to blood pressure measurements, which was needed in the other group. This added another advantage to the dexmedetomidine.
Our study has multiple limitations; first, it is a single center study that included a relatively small sample size. Furthermore, the efficacy of dexmedetomidine in patients with preexisting heart disease should have been studied. In addition, stress hormone levels (like cortisol) should have been evaluated as well. These drawbacks should be well covered in the upcoming studies.
| Conclusion|| |
Based on our findings, although dexmedetomidine and propofol are associated with comparable intraoperative hemodynamic changes and blood loss, the former drug appears to be superior regarding pain control, postoperative analgesic requirement.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Batra A, Verma R, Bhatia VK, Chandra G, Bhushan S. Dexmedetomidine as an anesthetic adjuvant in intracranial surgery. Anesth Essays Res 2017;11:309-13.
] [Full text]
Horvat A, Kolak J, Gopcević A, Ilej M, Zivko G. Anesthetic management of patients undergoing pituitary surgery. Acta Clin Croat 2011;50:209-16.
Nemergut EC, Dumont AS, Barry UT, Laws ER. Perioperative management of patients undergoing transsphenoidal pituitary surgery. Anesth Anal 2005;101:1170-81.
Lim M, Williams D, Maartens N. Anaesthesia for pituitary surgery. J Clin Neurosci 2006;13:413-8.
Shams T, El Bahnasawe NS, Abu-Samra M, El-Masry R. Induced hypotension for functional endoscopic sinus surgery: A comparative study of dexmedetomidine versus esmolol. Saudi J Anaesth 2013;7:175-80.
Srivastava U, Dupargude AB, Kumar D, Joshi K, Gupta A. Controlled hypotension for functional endoscopic sinus surgery: Comparison of esmolol and nitroglycerine. Indian J Otolaryngol Head Neck Surg 2013;65:440-4.
Zhou W, Chen X, Hou R, Shen B. Clinical study of controlled hypotension with magnesium sulphate during functional endoscopic sinus surgery. J Shanghai Jiaotong Univ (Medical Science) 2009;29:1502-5.
Barak M, Yoav L, Abu el-Naaj I. Hypotensive anesthesia versus normotensive anesthesia during major maxillofacial surgery: A review of the literature. ScientificWorldJournal 2015;2015:480728.
Liu Y, Liang F, Liu X, Shao X, Jiang N, Gan X. Dexmedetomidine reduces perioperative opioid consumption and postoperative pain intensity in neurosurgery: A meta-analysis. J Neurosurg Anesthesiol 2018;30:146-55.
Gerlach AT, Dasta JF. Dexmedetomidine: An updated review. Ann Pharmacother 2007;41:245-54.
Lee S. Dexmedetomidine: Present and future directions. Korean J Anesthesiol 2019;72:323-30.
Bala R, Chaturvedi A, Pandia MP, Bithal PK. Intraoperative dexmedetomidine maintains hemodynamic stability and hastens postoperative recovery in patients undergoing transsphenoidal pituitary surgery. J Neurosci Rural Pract 2019;10:599-605.
Boezaart AP, van der Merwe J, Coetzee A. Comparison of sodium nitroprusside- and esmolol-induced controlled hypotension for functional endoscopic sinus surgery. Can J Anaesth 1995;42:373-6.
Biro P. Calculation of volatile anaesthetics consumption from agent concentration and fresh gas flow. Acta Anaesthesiol Scand 2014;58:968-72.
Orhon ZN, Devrim S, Celik M, Dogan Y, Yildirim A, Basok EK. Comparison of recovery profiles of propofol and sevoflurane anesthesia with bispectral index monitoring in percutaneous nephrolithotomy. Korean J Anesthesiol 2013;64:223-8.
Agoliati A, Dexter F, Lok J, Masursky D, Sarwar MF, Stuart SB, et al.
Meta-analysis of average and variability of time to extubation comparing isoflurane with desflurane or isoflurane with sevoflurane. Anesth Anal 2010;110:1433-9.
Heller GZ, Manuguerra M, Chow R. How to analyze the visual analogue scale: Myths, truths and clinical relevance. Scand J Pain 2016;13:67-75.
Schwarz A, Nossaman B, Carollo D, Ramadhyani U. Dexmedetomidine for neurosurgical procedures. Curr Anesthesiol Rep 2013;3:205-9.
Moshiri E, Modir H, Yazdi B, Susanabadi A, Salehjafari N. Comparison of the effects of propofol and Dexmedetomidine on controlled hypotension and bleeding during endoscopic sinus surgery. Ann Trop Med Public Health 2017;10:721-5. [Full text]
Godbole RD, Bhattacharya B, Saleem T, Patil S, Resoju R, Patil P. A comparative study between propofol and dexmedetomidine for hypotensive anesthesia in ENT surgeries in Indian phenotype. J Med Sci 2019;5:81-7.
Sturaitis M, Kroin J, Swamidoss CP, Moric M. Effects of intraoperative dexmedetomidine infusion on hemodynamic stability during brain tumor resection. Anesthesiology 2002;97:A310.
Tanskanen PE, Kyttä JV, Randell TT, Aantaa RE. Dexmedetomidine as an anaesthetic adjuvant in patients undergoing intracranial tumour surgery: A double-blind, randomized and placebo-controlled study. Br J Anaesth 2006;97:658-65.
Gopalakrishna KN, Dash PK, Chatterjee N, Easwer HV, Ganesamoorthi A. Dexmedetomidine as an anesthetic adjuvant in patients undergoing transsphenoidal resection of pituitary tumor. J Neurosurg Anesthesiol 2015;27:209-15.
Ali Z, Prabhakar H, Bithal PK, Dash HH. Bispectral index-guided administration of anesthesia for transsphenoidal resection of pituitary tumors: A comparison of 3 anesthetic techniques. J Neurosurg Anesthesiol 2009;21:10-5.
Salimi A, Sharifi G, Bahrani H, Mohajerani SA, Jafari A, Safari F, et al.
Dexmedetomidine could enhance surgical satisfaction in Trans-sphenoidal resection of pituitary adenoma. J Neurosurg Sci 2017;61:46-52.
Yildiz M, Tavlan A, Tuncer S, Reisli R, Yosunkaya A, Otelcioglu S. Effect of dexmedetomidine on haemodynamic responses to laryngoscopy and intubation: Perioperative haemodynamics and anaesthetic requirements. Drugs R D 2006;7:43-52.
Uyar AS, Yagmurdur H, Fidan Y, Topkaya C, Basar H. Dexmedetomidine attenuates the hemodynamic and neuroendocrinal responses to skull-pin head-holder application during craniotomy. J Neurosurg Anesthesiol 2008;20:174-9.
Bekker A, Sturaitis M, Bloom M, Moric M, Golfinos J, Parker E, et al.
The effect of dexmedetomidine on perioperative hemodynamics in patients undergoing craniotomy. Anesth Analg 2008;107:1340-7.
Kanaya N, Hirata N, Kurosawa S, Nakayama M, Namiki A. Differential effects of propofol and sevoflurane on heart rate variability. Anesthesiology 2003;98:34-40.
Ebert TJ, Muzi M, Berens R, Goff D, Kampine JP. Sympathetic responses to induction of anesthesia in humans with propofol or etomidate. J Am Soc Anesthesiol 1992;76:725-33.
Nair S, Collins M, Hung P, Rees G, Close D, Wormald PJ. The effect of β-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope 2004;114:1042-6.
Marzban S, Haddadi S, Mahmoudi Nia H, Heidarzadeh A, Nemati S, Naderi Nabi B. Comparison of surgical conditions during propofol or isoflurane anesthesia for endoscopic sinus surgery. Anesth Pain Med 2013;3:234-8.
Boonmak P, Boonmak S, Laopaiboon M. Deliberate hypotension with propofol under anaesthesia for functional endoscopic sinus surgery (FESS). Cochrane Database Syst Rev 2016;10:CD006623.
Muniyappa RB, Rajappa GC, Govindswamy S, Thamanna PP. Effect of dexmedetomidine bolus dose on isoflurane consumption in surgical patients under general anesthesia. Anesth Essays Res 2016;10:649-54.
] [Full text]
Weerink MA, Struys MM, Hannivoort LN, Barends CR, Absalom AR, Colin P. Clinical pharmacokinetics and pharmacodynamics of dexmedetomidine. Clin Pharmacokinet 2017;56:893-913.
Gertler R, Brown HC, Mitchell DH, Silvius EN, editors. Dexmedetomidine: A novel sedative-analgesic agent. In: Baylor University Medical Center Proceedings. Bumc Proceedings Taylor & Francis; 2001;14:13-21.
Nunes RR, Cavalcante SL. Influence of dexmedetomidine upon sevoflurane end-expiratory concentration. Evaluation by bispectral index, suppression rate and electroencephalographic power spectral analysis. Rev Bras Anestesiol 2002;52:133-45.
Magalhães E, Govêia CS, Ladeira LC, Espíndola BV. Relationship between dexmedetomidine continuous infusion and end-tidal sevoflurane concentration, monitored by bispectral analysis. Rev Bras Anestesiol 2004;54:303-10.
Günes Y, Gündüz M, Özcengiz D, Özbek H, Isik G. Dexmedetomidine-remifentanil or propofol-remifentanil anesthesia in patients undergoing intracranial surgery. Neurosurg Q 2005;15:122-6.
Ilhan O, Koruk S, Serin G, Erkutlu I, Oner U. Dexmedetomidine in the supratentorial craniotomy. Eurasian J Med 2010;42:61-5.
Coursin DB, Coursin DB, Maccioli GA. Dexmedetomidine. Curr Opin Crit Care 2001;7:221-6.
[Table 1], [Table 2], [Table 3], [Table 4]