|Year : 2016 | Volume
| Issue : 2 | Page : 235-240
Effect of dexmedetomidine to attenuate the sympathetic response of laryngoscopy and intubation and perioperative hemodynamic stability in patients undergoing neurosurgery
Nilesh Maganbhai Solanki1, Rekha Nilesh Solanki2, Ritesh J Patel1, Ankur Garg1
1 Department of Anaesthesia, B. J. Medical College and Civil Hospital, Ahmedabad, Gujarat, India
2 Department of Anaesthesia, Gujarat Cancer Research Institutes, M. P. Shah Cancer Hospital, Civil Hospital, Asarwa, Ahmedabad, Gujarat, India
|Date of Web Publication||29-Sep-2016|
Nilesh Maganbhai Solanki
44 Devshrusti Bungalows-II, B/h Kena Bungalows, Motera Stadium Road, Motera, Sabarmati, Ahmedabad - 380 005, Gujarat
Source of Support: None, Conflict of Interest: None
Background and Aims: Dexmedetomidine is a selective α2 agonist used as an adjuvant to attenuate sympathetic response to laryngoscopy and tracheal intubation in general anesthesia. Recent studies have shown that dexmedetomidine decreases brain flow and cerebrospinal fluid pressure without cerebral ischemia. Hence, it is beneficial in neurosurgical procedures. This study was undertaken to analyze the efficacy of dexmedetomidine in neurosurgery for good perioperative hemodynamic stability with blunt sympathetic response to laryngoscopy and intubation.
Materials and Methods: Sixty, American Society of Anesthesiologists grades II-IV patients between 18 and 50 years of age undergoing craniotomy under general anesthesia were divided randomly into two groups (thirty patients in each group). Group D: Dexmedetomidine was given as a bolus dose of 1 μg/kg diluted to a total volume of 20 ml with normal saline (0.9%) for 10 min before the induction of anesthesia. Group C: The patients received a similar volume of normal saline.
Results: We observed a decrease in blood pressure and heart rate (HR) after intubation by dexmedetomidine, and they were highly significant on comparison (P < 0.0001). During intraoperative period, the patients in Group D had lower HR and blood pressure than baseline value as compared to Group C (P < 0.0001). We also observed decreased requirement of sevoflurane (33%) and fentanyl (45%) in Group D compared to Group C. Data were expressed as mean values ± standard deviation. P <0.05 was considered to be significant.
Conclusion: Dexmedetomidine blunted the hemodynamic stress response due to laryngoscopy and intubation and perioperative hemodynamic stability in patients undergoing neurosurgery.
Keywords: Dexmedetomidine, general anesthesia, laryngoscopy and intubation, neurosurgery
|How to cite this article:|
Solanki NM, Solanki RN, Patel RJ, Garg A. Effect of dexmedetomidine to attenuate the sympathetic response of laryngoscopy and intubation and perioperative hemodynamic stability in patients undergoing neurosurgery. Indian J Health Sci Biomed Res 2016;9:235-40
|How to cite this URL:|
Solanki NM, Solanki RN, Patel RJ, Garg A. Effect of dexmedetomidine to attenuate the sympathetic response of laryngoscopy and intubation and perioperative hemodynamic stability in patients undergoing neurosurgery. Indian J Health Sci Biomed Res [serial online] 2016 [cited 2020 Jul 14];9:235-40. Available from: http://www.ijournalhs.org/text.asp?2016/9/2/235/191280
| Introduction|| |
Laryngoscopy and endotracheal intubation due to sympathetic response increase the blood pressure and heart rate (HR), which is hazardous to those patients undergoing neurosurgery for brain tumor. , Hypertension during intubation in neurosurgical patients may be associated with an increase in intracranial pressure (ICP) and intracranial bleed, which may increase the morbidity in such patients and prolonged hospital stay. 
Dexmedetomidine is an α2 adrenergic receptor agonist, its sympatholytic and antinociceptive properties allow for hemodynamic stability at critical moments of neurosurgical stimulation. 
We studied to evaluate the efficacy of dexmedetomidine to attenuate the sympathetic response of laryngoscopy and intubation and perioperative hemodynamic stability in patients undergoing elective neurosurgical procedures.
| Materials and Methods|| |
After obtaining the Ethics Committee approval, this study was conducted in the neurosurgical operation theater in our institute, total 60 American Society of Anaesthesiologist (ASA) grades II-IV patients, aged 18-50 years, undergoing elective neurosurgical procedures under general anesthesia were enrolled in the present study. After taking informed consent, patients were classified randomly into two equal groups of thirty each. Patients with ASA Grade III/IV, age <18 years and >50 years, arrhythmias, heart blocks, drug allergy, pregnant and nursing women, and major hepatic, renal, or endocrine dysfunction were excluded from the study. Patients refusing to give consent for the study were also excluded.
The research methodology was prospectively randomized with the help of computer-generated coded envelopes, and the patients were divided into two groups: Group D and Group C.
In the operation room after establishing intravenous (IV) access, the baseline parameters were observed and recorded, which included HR, noninvasive blood pressure, electrocardiogram, pulse oximetry (SpO 2 ), and end-tidal carbon dioxide (EtCO 2 ). The patients were premedicated with IV doses of injection glycopyrrolate 0.2 mg, injection ondansetron 4 mg, and injection fentanyl 1 μg/kg. Patients in Group D received injection dexmedetomidine as a bolus dose of 1 μg/kg diluted to a total volume of 20 ml with normal saline (0.9%) for 10 min through an infusion pump prior to the induction of anesthesia. Patients in Group C received 20 ml of 0.9% saline for10 min. A subjective sedation score, derived from Ramsay's sedation score, was employed for the purpose of the evaluation of sedation effect in both groups.  Induction was done with injection thiopentone (4-6 mg/kg), which was sufficient to abolish eyelash reflex, followed by 0.1 mg/kg of injection vecuronium bromide to provide neuromuscular blockage. Thereafter, laryngoscopy was performed with a Macintosh laryngoscope, and endotracheal intubation was performed with a cuffed endotracheal tube of appropriate size. The hemodynamic parameters were recorded immediately after intubation and 1 min, 5, 10, and 15 min after intubation till the completion of the surgery. Response to skin incision was also observed and recorded in a similar manner. Anesthesia was maintained with nitrous oxide in oxygen 60:40% and sevoflurane (1-1.5%). During perioperative period, an incremental dose of fentanyl was given in Group C to maintain hemodynamic stability. Ventilation was adjusted to maintain an EtCO 2 value between 30 and 35 mmHg. The EtCO 2 values were kept between 30 and 35 in cases with a probability of increased ICP secondary to their pathology. Injection mannitol was administered wherever required at a dose of 1-1.5 g/kg after 15 min of intubation. Any hypotension (systolic blood pressure [SBP] <20% baseline) was managed according to the status of central venous pressure (CVP). If CVP was low, a fluid bolus of normal saline of 250-300 ml was administered. If hypotension did not respond to fluid administration, injection mephentermine 3 mg IV was administered. If hypotension did not respond to two repeat doses of mephentermine, other means were sought as per the need. Any incidence of bradycardia (HR <50/min) was treated with injection atropine 300 μg IV.
The sevoflurane was used in lowest possible concentration necessary to keep the blood pressure and HR within 20% limits of patient's preoperative baseline values. On completion of the surgery, the neuromuscular blockade was reversed with injection neostigmine0.05 mg/kg and injection glycopyrrolate 0.01 mg/kg intravenously, and the patients were extubated when they were able to obey simple commands.
In this study, the sample size was calculated using the formula n = 4 pq/E 2 , which is based on Hardy-Weinberg principle. In this formula, P is the prevalence of craniotomy at our institute.
Sixty patients were allocated randomly to two equal groups (thirty patients/group). Data were expressed as mean values ± standard deviation. Categorical variables were analyzed using Chi-square test with Yate's correction and Fisher's exact test (two-tailed) as appropriate. Continuous variables were tested using an unpaired Student's t-test. Statistical calculations were carried out using Microsoft Office Excel 2010 and Graph Pad Prism 6.05 (QuickCalc) software (GraphPad software Inc., La Jolla CA, USA). P <0.05 was considered to be statistically significant, P < 0.001 was taken as highly significant, and P > 0.05 was regarded as nonsignificant.
| Results|| |
No statistically significant difference was observed in both the groups regarding age, sex, weight, ASA grade and duration of surgery [Table 1]. Dexmedetomidine was well tolerated, and no drug-related adverse events were observed. After receiving dexmedetomidine, the patients were drowsy, but arousable [Table 2]. Majority of the patients in both groups underwent glioma and meningioma surgeries [Table 3].
Primary outcome of the study
There was no difference in baseline hemodynamic parameters among the groups (P = 0.2883). After intubation, an increase in HR was observed in Group C compared to Group D. Similarly, after extubation, the trends were same (P < 0.0001). In the intraoperative period, the reference value was taken as 30 min after intubation. During intraoperative period, the patients in Group D had lower HRs than baseline value as compared to Group C (P < 0.0001), which was highly significant [Table 4]. In Group C, there was a statistically highly significant change in SBP and diastolic blood pressure (DBP) after intubation, during intraoperative period, and after extubation (P < 0.0001) [Table 5] and [Table 6].
Secondary outcomes of the study
The mean sleep dose of injection thiopentone required in Group C was 6 mg/kg, while it was 4.5 mg/kg in Group D. The decrease in the dose requirement was by 25% in Group D as compared to Group C.
The average inspiratory concentration of sevoflurane required during anesthetic maintenance was 1.5% in Group C and 1% in Group D. A decrease of 33% was observed in Group D compared to Group C [Table 7].
In addition, the requirement of injection fentanyl was 1.8 μg/kg in Group C as compared to 1 μg/kg in Group D. Patients in Group D required 45% of reduced dose of fentanyl as compared to Group C patients.
Bradycardia (HR <50/min) was observed in only two patients receiving dexmedetomidine, which responded to the administration of IV atropine 300 μg. This fall in HR was not associated with a decrease in blood pressure. No other side effects were observed in Group C.
The duration of recovery was similar in both the groups. All the patients were immediately able to obey commands upon arrival into recovery room.
In the recovery room, two patients in Group D and one patient in Group C experienced nausea. None of the patients complained of any discomfort after operation.
| Discussion|| |
The goals of neuroanesthesia are to provide good operating condition without sudden increases in ICP or acute brain swelling. Hemodynamic pressor response to laryngoscopy and intubation has been a constant problem for anesthesiologists, and multiple pharmacological agents have been used to counteract this. Tracheal intubation is associated with increases in arterial pressure, HR, and plasma catecholamine concentrations. 
Blood pressure elevations during direct laryngoscopy for tracheal intubation begin to manifest after 15 s and reach the peak if laryngoscopy is continued for 30-45 s. However, in situations when a rapid laryngoscopy is not assured or when a high-risk patient is involved (coronary artery disease, intracranial hypertension, and intracranial aneurysm), it would seem prudent to attenuate blood pressure surges that are pharmacologically associated with laryngoscopy and intubation.
α2 agonists are known to reduce anesthetic requirements, and because of sympatholytic properties, to afford hemodynamic stability during the intraoperative period.  Dexmedetomidine decreases plasma epinephrine and norepinephrine levels perioperatively.  In addition, dexmedetomidine-loading infusion showed its efficacy and safety to several kinds of operative patients by decreasing the hemodynamic response to endotracheal intubation, catecholamine discharge, and surgical stress, thus providing hemodynamic stability. ,,
Dexmedetomidine has a high α2 agonist activity to decrease the plasma catecholamine levels and to suppress the release of catecholamines.  The use of dexmedetomidine is more effective than esmolol in preventing hypertensive response to laryngoscopy and intubation in neurosurgical patients. 
The use of dexmedetomidine is more effective compared to fentanyl to attenuate HR response to laryngoscopy and intubation. 
In intracranial surgery, increase or decrease in blood pressure may cause bleeding or edema or predispose the patient to cerebral ischemia. Dexmedetomidine blunted pressure response to intubation and emergence from anesthesia with preserved respiratory function in patients with intracranial tumors undergoing craniotomy. , Tanskanen et al. in their study using dexmedetomidine as an anesthetic adjuvant for intracranial tumor concluded that there was an increased perioperative hemodynamic stability in patients undergoing brain tumor surgery without postoperative respiratory depression.  Dexmedetomidine with a loading dosage of 1 μg/kg may induce more serious respiratory depression, and sometimes, headache and intracranial tumor in patients. 
We observed that dexmedetomidine blunted the stress response to laryngoscopy and provided a better perioperative hemodynamic stability in patients undergoing neurosurgery.
Dexmedetomidine, as a preanesthetic medication and intraoperative infusion, decreases intraoperative anesthetic requirement. It has a significant opioid and anesthetic-sparing property. It significantly attenuates sympathoadrenal response to tracheal intubation. 
Dexmedetomidine has been shown to reduce the minimum alveolar concentration of inhalational anesthetics and the requirement of perioperative fentanyl.  Intraoperative infusion of dexmedetomidine reduces perioperative analgesic requirements.  Dexmedetomidine used as an adjuvant to attenuate the pressor response to intubation, surgery, and extubation decreased the dose of opioids and isoflurane in patients undergoing general anesthesia. 
In our study, the dose requirement of thiopentone was reduced by 25% in Group D as compared to Group C. Similarly, concentrations of fentanyl and sevoflurane were decreased by 45% and 33%, respectively.
Gunes et al.  studied the infusion of dexmedetomidine as an adjuvant for a comparison of sevoflurane, desflurane, or isoflurane anesthesia in patients undergoing supratentorial craniotomy. The concentrations of anesthetic agents were lower throughout the study period than during the initial period. In the sevoflurane-dexmedetomidine group, the sevoflurane concentration was reduced by a mean of 50% from the induction of anesthesia to dural closure. Similarly, concentrations of desflurane and isoflurane were decreased by approximately 36% and 40%, respectively.
| Conclusion|| |
Dexmedetomidine, an adjuvant, is used to attenuate sympathetic response to laryngoscopy and tracheal intubation with good perioperative hemodynamic stability and to decrease the anesthetic requirements in patients undergoing craniotomy. Dexmedetomidine offers a unique combination of sedation, anxiolysis, and analgesia, without respiratory depression.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]