|Year : 2023 | Volume
| Issue : 1 | Page : 10-16
Comparison between dexmedetomidine and fentanyl on intubating condition to facilitate awake oral fibreoptic intubation under topical anaesthesia – A randomised controlled trial
Vishnu Panwar1, Sushil Krishnan2, Anil Kumar Sharma2
1 Department of Onco-Anesthesia and Palliative Medicine, Dr. BRAIRCH, AIIMS, New Delhi, India
2 Department of Anesthesia and Critical Care, Northern Railway Central Hospital, New Delhi, India
|Date of Submission||29-Jun-2022|
|Date of Acceptance||14-Mar-2023|
|Date of Web Publication||20-Apr-2023|
Department of Onco-Anesthesia and Palliative Medicine, Dr. BRAIRCH, AIIMS, Ansari Nagar, New Delhi
Source of Support: None, Conflict of Interest: None
Background and Aims: Awake fibreoptic intubation (AFOI) is the standard method of airway management in the anticipated difficult airway. While many drugs have been employed for sedation, there is no single drug that can be recommended as the drug of choice. Dexmedetomidine is characterised by effects of sedation, analgesia, amnesia and lack of respiratory depression. Hence, we hypothesised that dexmedetomidine should be suitable for AFOI and compared it to the control drug fentanyl. This study assesses the level of sedation and intubating conditions using dexmedetomidine or fentanyl during awake fibreoptic orotracheal intubation. Methods: Sixty adult patients, American Society of Anaesthesiology class I and II, who required orotracheal intubation during general anaesthesia with the normal airway were randomised to receive dexmedetomidine 0.6 μg/kg (Group A) or fentanyl 1.0 μg/kg (Group B) intravenous infusion for 10 min, after topical anaesthesia to the airway. A total of 60 patients were allocated, 30 patients in each group. The primary objective was to assess the intubating conditions with dexmedetomidine compared to fentanyl. Results: The intubation score for vocal cord movement (1.57 ± 0.68 in Group A vs 1.93 ± 0.75 in Group B) and cough (1.50 ± 0.78 in Group A vs 1.90 ± 0.72 in Group B), endoscopy score (2.17 ± 0.59 in Group A vs 2.47 ± 0.69 in Group B), sedation score (4.73 ± 0.5 in Group A vs 4.47 ± 0.57 in Group B) and patient satisfaction score (1.20 ± 0.41 in Group A vs 1.47 ± 0.68 in Group B) were statistically significant in patients receiving dexmedetomidine. During the procedure, there was a statistically and clinically significant increase in heart rate of 1.5% in Group A versus 22% in Group B, and an increase in mean arterial pressure of 1.95% in Group A versus and 10.27% in the Group B. Conclusion: Dexmedetomidine provided better intubation conditions than fentanyl, with greater haemodynamic stability, better sedation and greater patient satisfaction score compared to fentanyl during awake fibreoptic oral intubation.
Keywords: Awake sedation, dexmedetomidine, endoscopy score, fentanyl, fibreoptic intubation, intubation score, Observer Assessment of Alertness and Sedation Scale
|How to cite this article:|
Panwar V, Krishnan S, Sharma AK. Comparison between dexmedetomidine and fentanyl on intubating condition to facilitate awake oral fibreoptic intubation under topical anaesthesia – A randomised controlled trial. Airway 2023;6:10-6
|How to cite this URL:|
Panwar V, Krishnan S, Sharma AK. Comparison between dexmedetomidine and fentanyl on intubating condition to facilitate awake oral fibreoptic intubation under topical anaesthesia – A randomised controlled trial. Airway [serial online] 2023 [cited 2023 Jun 4];6:10-6. Available from: https://www.arwy.org/text.asp?2023/6/1/10/374363
| Introduction|| |
Among the recent innovations in the field of airway management, fibreoptic endotracheal intubation has had a tremendous impact on improving patient safety during a difficult intubation. An ideal intravenous sedation agent allows the patient to remain calm and fall asleep, if undisturbed, but at the same time, the patient will be easily arousable and capable of following verbal commands when spoken to.
An ideal agent for awake sedation would have the following features – it would be short-acting or reversible, with little or no respiratory depression, would ensure haemodynamic stability, with no or few significant side effects. Few agents have been used for sedation during awake fibreoptic bronchoscope (FOB), but all have their limitations. These include opioids, benzodiazepines, propofol, ketamine or combinations of the above. Fentanyl is a phenylpiperidine derivative of a synthetic opioid, which provides sedation and analgesia along with haemodynamic stability, which is beneficial for awake fibreoptic intubation (AFOI), but there is a risk of respiratory depression, nausea, vomiting, itching and chest wall rigidity.
Dexmedetomidine, an α2-adrenoreceptor agonist, could be a valuable drug for use during fibreoptic intubation as it induces sedation and analgesia without depressing respiratory function. Given in the appropriate doses, the cardiovascular effects can be tailored to maintain haemodynamic stability. Furthermore, patients commonly report xerostomia which is helpful in smooth fiberoscopy and intubation. It produces sedation, anxiolysis, amnesia and facilitates patient cooperation. These effects should thus make dexmedetomidine highly desirable for AFOI. Side effects like hypotension, bradycardia and dry mouth are reported. There is also a paucity of existing data in the Indian setting for this purpose.
The dose of dexmedetomidine used for sedation is 1 μg/kg i.v. over 10 min for AFOI in many studies. Based on preliminary information from pilot cases, we hypothesise that dexmedetomidine in a dose of 0.6 μg/kg i.v. will be a safer and more efficacious choice compared to the standard drug fentanyl in a dose of 1 μg/kg i.v. for AFOI.
Our aim of the study was to evaluate the efficacy of dexmedetomidine for sedation in AFOI. Our primary objective is to assess the intubation condition with dexmedetomidine compared to fentanyl.
The secondary objectives were to compare sedation levels between dexmedetomidine and fentanyl; to compare haemodynamic parameters like blood pressure, and heart rate and respiratory parameters like oxygen saturation during sedation; to assess patient satisfaction score; any adverse outcome (hoarseness, sore throat and bronchospasm); the amount of lignocaine used for the topicalisation of the airway and the amount of intravenous propofol used as a rescue drug for sedation.
| Methods|| |
The study was conducted after obtaining approval from the Institutional ethical committee. It was planned as a randomised, double-blind, prospective study. Based on previous study results, we required 28 subjects in each group to demonstrate a 10% difference in the intubation score with a power of 0.9 and a type one error of 0.05. We, therefore, enrolled 60 patients, 30 in each group.
Patients of the age group of 20–70 years, American Society of Anaesthesiology physical status I and II who were planned to undergo elective surgery under general anaesthesia were included. The procedure was properly explained, and written informed consent was taken. Patients with anticipated difficult airway, Mallampati grading >3 and thyromental distance <6.5 cm, history of bleeding diathesis, severe bradycardia, raised intracranial pressure, uncontrolled seizure disorder, known psychiatric illness, elevated liver enzymes two times more than the upper normal limit and pregnant women were excluded from the study.
Patients were randomly allocated using computer-generated random numbers and were divided into two groups. Group A – Dexmedetomidine group (n = 30) and Group B – Fentanyl group (n = 30). Allocation concealment was done using sealed opaque envelopes. The 'study drug' was prepared and coded by an anaesthesiologist who was not concerned with patient management and data collection. Both the anaesthesiologists who administered the drug as well as who did data collection were blinded to the drug administered. Bronchoscopy was performed by a single anaesthesiologist on all patients.
All patients were given a tablet of ranitidine 150 mg orally at 6 am on the day of surgery. Intramuscular glycopyrrolate 0.2 mg was given 45 min before the procedure. The study drug was prepared as 200 μg (2 ml) of dexmedetomidine (dextomid 200 μg –2 ml, Neon, India) in 50 ml of 0.9% saline in Group A and 200 μg (4 ml) of fentanyl citrate (Verfen, 50 μg/ml –2 ml, Verve, India) in 50 ml of 0.9% saline in Group B.
On arrival in the operation theatre, baseline blood pressure, heart rate and oxygen saturation were recorded. Intravascular access was secured, and nasal oxygen (2 L/min) using nasal prongs was applied in all the patients. Each patient received a loading dose of either dexmedetomidine (0.6 μg/kg) or fentanyl (1.0 μg/kg) intravenous infusion for 10 min. During this period, the patient's airway was topicalised with nebulisation of 5 ml of 4% lignocaine (dose = 200 mg). At the end of nebulisation, a single puff of topical xylocaine 10% was given in the hypopharynx (dose = 10 mg).
After the test drug was infused, the sedation level was evaluated by the Observer's Assessment of Alertness/ Sedation Scale (OAA/S). A single designated anaesthesiologist performed AFOI via an Ovassapian airway with a 7.5 mm endotracheal tube (ETT) in males or 7.0 mm cuffed ETT in females. Once the glottic structures were identified, additional boluses of 2 ml of 2% xylocaine were injected into the trachea via the working channel of FOB as required using spray-as-you-go technique. It was ensured that the total dose of 9 mg/kg lignocaine was not exceeded. After adequate anaesthesia of the glottis structures was achieved, the FOB was maneuvered across the vocal cords into the trachea and positioned just above the carina. If the required intubating condition was not present (vocal cord score >3, cough score >3, limb movement >3), then rescue sedation with 10 mg boluses of propofol iv was administered as required. The ETT was railroaded over the FOB into the trachea 2–3 cm above the carina. The cuff was inflated, the FOB was withdrawn, the ETT was connected to the breathing circuit and tracheal intubation further confirmed by capnography. After that confirmation, general anaesthesia was induced with intravenous (iv) propofol and atracurium was administered iv, and surgery was allowed to proceed.
One observer recorded endoscopy and sedation scores as well as haemodynamic and respiratory parameters during the procedure (baseline, after sedation, after bronchoscopy, immediately after intubation and 2 min after intubation). Intravenous boluses of phenylephrine 50 mcg and atropine 0.6 mg were used to treat episodes of hypotension (fall in BP > 20 % of baseline value) and bradycardia (HR <60 beats/minute) respectively.
Sedation was measured with the Observer's assessment of Alertness/Sedation (OAA/S) Scale at the end of drug infusion as follows: responds readily to name spoken in normal tone (awake/alert), 5 points; lethargic response to name spoken in a normal tone, 4 points; responds only after the name is spoken loudly or repeatedly, 3 points; responds after mild prodding or shaking, 2 points and does not respond to mild prodding or shaking, 1 point.
Endoscopy score was used to assess the ease of bronchoscopy as follows: grimacing, 1; localising, 2; coughing on lignocaine via scope, 3; coughing on entering glottic space, 4; prolonged coughing, 5.
The intubation score was used for assessing the ease of intubation.
- Vocal cord movement: 1 = Open; 2 = Moving; 3 = Closing; 4 = Closed
- Cough: 1 = None; 2 = Slight; 3 = Moderate; 4 = Severe
- Limb movement: 1 = None; 2 = Slight; 3 = Moderate; 4 = Severe.
Intubation time (starting of fibreoptic bronchoscopy to confirmation of tracheal intubation with capnography) and intubation attempts were noted.
Patient satisfaction score was assessed using a 3-point Likert scale (1 = Excellent, 2 = Good, 3 = Bad), recorded 24 h after intubation. Excellent means the patient found the procedure comfortable, good means the patient found the procedure tolerable and bad means the patient recalled the procedure causing discomfort.
Statistical analysis of the data collected was performed using the software package SPSS (Statistical Package for the Social Sciences, Chicago, IL, USA) 17. Normally distributed variables were tested with a t-test and ordinal variables, or not normally distributed variables, were analysed with the Mann–Whitney U-test, Fisher's exact test for 2 × 2 tables was used and all tests were two-tailed with a confidence level of 95% (P < 0.05).
| Results|| |
We screened 103 patients, out of which 43 patients were excluded due to not meeting the inclusion criteria and not giving consent. Total 60 patients were studied [Figure 1]. The demographic profiles (age, weight, and sex distribution) were comparable between the two groups [Table 1].
The mean endoscopy score in Group A (dexmedetomidine group) was 2.17 ± 0.59 and in Group B (fentanyl group), it was 2.47 ± 0.69 (P = 0.03). It means bronchoscopy was more comfortable in the dexmedetomidine group than the fentanyl group [Table 2].
The intubation score consists of vocal cord movement, coughing and limb movement. Vocal cord movement score was 1.57 ± 0.68 and 1.93 ± 0.75 in Groups A and B, respectively (P = 0.02). Coughing scores were 1.50 ± 0.78 and 1.90 ± 0.72 in Groups A and B, respectively (P = 0.02). Limb movement score was 1.20 ± 0.48 and 1.37 ± 0.61 in Groups A and B, respectively (P = 0.124) [Table 2].
The mean sedation score in the dexmedetomidine group was 4.73 ± 0.5, while 4.47 ± 0.57 in the fentanyl group (P = 0.02) [Table 2].
Baseline parameters such as heart rate, mean arterial pressure and oxygen saturation (SpO2) were comparable between the two groups. During the procedure increase in mean heart rate was observed in both groups. It increased by 1.22% in the dexmedetomidine group and by 20.08% in the fentanyl group (P = 0.003) [Table 3]. During intubation, mean arterial pressure maximally increased by 2.06% in the dexmedetomidine group and by 11.75% in the fentanyl group from baseline (P = 0.008) [Table 4].
There was a fall in mean SpO2 during intubation from the baseline value in both groups up to 98.50% (P < 0.01) in the dexmedetomidine group and up to 98.17% (P < 0.01) in the fentanyl group, although it was clinically not significant. The mean time for intubation was 4.53 ± 1.74 min in the dexmedetomidine group, while in the fentanyl group, it was 4.63 ± 2.17 min (P = 0.42). Mean intubation attempts were 1.10 and 1.20 in the dexmedetomidine and fentanyl groups, respectively.
The total dose of lignocaine used in the dexmedetomidine group was 260 ± 13.65 mg, while in the fentanyl group, it was 270 ± 20.34 mg (P = 0.014) and the total dose of propofol used in the dexmedetomidine group was 14.67 ± 25.29 mg while in the fentanyl group, it was 23.00 ± 27.81 mg (P = 0.11). In dexmedetomidine group, 8 patients, while fentanyl group 13 patients received rescue propofol.
Two patients (6.67%) complained of sore throat in the dexmedetomidine group, while in the fentanyl group, 3 (10%) patients had a sore throat. 2 (6.67%) patients in the dexmedetomidine group and 4 (13.33%) patients in fentanyl group complained of hoarseness in the postoperative period. No incidence of intraoperative complications such as bleeding, bronchospasm and postoperative nausea and vomiting, were observed in both groups. None of the cases required active intervention.
Twenty-three patients out of 30 patients experienced AFOI with dexmedetomidine sedation as excellent, the mean patient satisfaction score in the dexmedetomidine group was 1.20 ± 0.41 while it was 1.47 ± 0.68 in the fentanyl group (P = 0.03) [Table 5].
| Discussion|| |
AFOI is the gold standard for anticipated difficult airway management till now. It is well tolerated when done under sedation. Various drugs have been studied for their sedation effects during AFOI. The role of fentanyl is already well-known for awake sedation during FOB with some side effects. Dexmedetomidine is a relatively newer drug, and its use for sedation during AFOI is emerging.,, We found that dexmedetomidine (0.6 μg/kg i.v.) for AFOI produced better intubating conditions, greater haemodynamic stability, provided better sedation and was associated with higher patient satisfaction scores compared to fentanyl.
We compared intravenous dexmedetomidine (0.6 μg/kg) for the facilitation of AFOI with fentanyl (1 μg/kg). After a study of pilot cases with 1 μg/kg dexmedetomidine infusion, we found profound hypotension and bradycardia in patients, which tally with the study by Avitsian et al. Recently, Cattano et al. showed that using a small loading dose of dexmedetomidine (0.4 μg/kg over 10 min) provides adequate sedation for AFOI. Hence, we decided to use a 0.6 μg/kg dose of dexmedetomidine in our patients. Even on this dose, we found a mild fall in blood pressure and pulse rate, but this was beneficial in our patients because it gave haemodynamically stable patients.
Patients in the dexmedetomidine group responded well when their name was spoken in a normal tone, while patients in the fentanyl group had a lethargic response (P = 0.02). The studies conducted by Shimabukuro and Satoh et al., Yildiz et al. and Mondal et al. had similar results, but an exact comparison could not be made due to the use of different sedation scales.,,
The endoscopy score was better in the dexmedetomidine, which is similar to a study conducted by Hu et al.
The intubation score in our study is slightly lower than Tsai et al. study, which could be explained by the use of a low dose of dexmedetomidine.
The intubation scores in our study were also similar to the study conducted by Chu, Mondal and Bergese et al.,, However, they did not use the same intubation scores so an exact comparison could not be made. The combined effect of dexmedetomidine and glycopyrrolate in our study decreased airway secretions and the use of local anaesthetics effectively reduced the incidence of coughing and gag reflex.
At the time of intubation, statistically significant rise in heart rate was noted in the fentanyl group (P = 0.00275). Similar findings were found in the study conducted by Chu, Yildiz and Scheinin et al.,,
In dexmedetomidine, group mean arterial pressure (MAP) increased during bronchoscopy and intubation, which was not statistically significant, but in the fentanyl group, there was a significant rise in MAP during AFOI (P = 0.008). In our study, the maximum average increase (vs baseline) in systolic blood pressure was 3% and 0.084% in diastolic blood pressure in dexmedetomidine. The patients remain more haemodynamically stable in our study compared to the Scheinin et al. study due to the topicalisation of the airway.
A clinically insignificant change in oxygen saturation was noted during the airway instrumentation. Similar findings were seen in the study using dexmedetomidine conducted by Scher and Gitlin et al.
The total amount of lignocaine used in dexmedetomidine group patients was lower than that in the fentanyl group. Efthimiou et al., in their study, used 9.3 mg/kg of lignocaine without clinical evidence of any toxicity. In our study, the total dose of lignocaine used was 5 mg/kg, which is within the therapeutic range. The lower amount of lignocaine used in dexmedetomidine group patients was probably due to better sedation level, hence better intubation scores and better cooperation of the patient achieved during AFOI.
Patient satisfaction score was better in the dexmedetomidine group compared to the fentanyl group. The better sedation and amnesia in the dexmedetomidine group probably made our patients better satisfied with the procedure. In the study conducted by Chu and Hu et al. most patients rated the satisfaction score as excellent and good, which is similar to our study.,
Special features of our study include a lower dose of dexmedetomidine used, so we did not encounter a profound fall in haemodynamic variables, with an adequate level of sedation. We calculated both the endoscopy score and intubation score, so it differentiated the ease of bronchoscopy and intubation both in the dexmedetomidine and fentanyl groups. We also calculated doses of lignocaine and rescue doses of propofol used.
A limitation of our study was that creating a comparable sedation state for the patient using two drugs of different classes was difficult. We attempted to override this difficulty by using the OASS sedation score, but it was still obvious that the nature of sedation differed in the two groups. Further, our study was performed in patients with no anticipated difficulty in airway management.
| Conclusion|| |
Our study found that dexmedetomidine used at a dose of 0.6mcg/kg provided more haemodynamic stability, a favorable sedation level, and better intubating condition than fentanyl for facilitation of awake oral fiberoptic intubation. Patients sedated with dexmedetomidine required a low dose of a local anaesthetic to topicalise the airway and had a better satisfaction score compared to fentanyl.
We concluded that a lower dose of dexmedetomidine is a better option available for the facilitation of awake fiberoptic intubation than fentanyl.
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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]