|Ahead of print publication
Comparison between intravenous dexmedetomidine and spray as you go with 4% lignocaine versus intravenous fentanyl and transtracheal injection of 4% lignocaine for awake nasotracheal intubation with flexible vedioscope – A randomized single-blind prospective study
Miriyala Pavan Kumar, Madhusmita Patro, Sasmita Panigrahy, Soumya Samal, B Sai Kartheek
Department of Anaesthesiology and Critical Care, IMS and SUM Hospital, Bhubaneswar, Odisha, India
|Date of Submission||28-May-2021|
|Date of Acceptance||04-Jul-2021|
|Date of Web Publication||16-Dec-2021|
Department of Anaesthesiology and Critical Care, IMS and SUM Hospital, Bhubaneswar - 751 003, Odisha
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Awake fiber-optic bronchoscopy-guided intubation is the method of choice in difficult airway which requires effective airway anesthesia to ensure patient comfort and acceptance. Aims: This study was conducted to assess the quality of airway anesthesia, patient comfort during intubation, and postoperative satisfaction of patients. Settings: Patients posted for surgeries under general anesthesia with Mallampati Grade I and II in a medical college. Patients were followed in the operation theater and postoperative ward. Study Design: This was a prospective randomized single-blind study. Materials and Methods: Group D received intravenous (i.v.) dexmedetomidine 1 μg.kg−1 i.v. over 10 min and 3 ml of 4% lignocaine spray as you go (SAYGo). Group F received i.v. fentanyl 2 μg.kg−1 over 10 min and transtracheal injection 3 ml of 4% lignocaine. Parameters assessed were endoscopic time, intubating condition, vocal cord position, cough severity, comfort during intubation, postoperative patient satisfaction, and any adverse effects such as sore throat, hoarseness, unpleasant memories, and hemodynamic response during intubation. Statistical Analysis: Independent Student's t-test, Mann–Whitney, Chi-squared test, or Fisher's exact test were used. P ≤ 0.05 was considered statistically significant. Results: Intubating conditions, vocal cord position, cough severity, comfort during intubation, and postoperative patient satisfaction were statistically significant (P ≤ 0.05) in favor of Group D though endoscopic time was longer. Conclusion: IV dexmedetomidine with SAYGo is effective than IV fentanyl with transtracheal block for awake fiber-optic videoscopic intubation in terms of intubating conditions, vocal cord position, cough severity, comfort during intubation, and postoperative satisfaction of patients with significant attenuation of postintubation hemodynamic response and better preservation of respiration though endoscopic time is more.
Keywords: Awake intubation, dexmedetomidine, fentanyl, flexible videoscope, spray as you go, transtracheal block
|How to cite this URL:|
Kumar MP, Patro M, Panigrahy S, Samal S, Kartheek B S. Comparison between intravenous dexmedetomidine and spray as you go with 4% lignocaine versus intravenous fentanyl and transtracheal injection of 4% lignocaine for awake nasotracheal intubation with flexible vedioscope – A randomized single-blind prospective study. Anesth Essays Res [Epub ahead of print] [cited 2022 Jul 3]. Available from: https://www.aeronline.org/preprintarticle.asp?id=332713
| Introduction|| |
Administration of general anesthesia can be difficult during unanticipated difficult airway if the aiway is not secured before intubation. The gold standard in the management of patients with a suspected difficult airway is awake fiber-optic intubation (AFOI). AFOI is done after attaining “conscious sedation.” Conscious sedation is a state where the patient airway and spontaneous respiration is intact, but the airway reflexes are blunt. Appropriate anesthesia of nose, oropharynx, larynx, and trachea is a prerequisite for suppressing airway reflexes and preventing discomfort to the patient during intubation. Conscious sedation a technique, which is desirable not only to make the procedure more tolerable for patient's but due ensure optimal intubating conditions, especially in the presence of abnormal orolaryngopharyngeal anatomy and pathology. Deeper plain of sedation may result in loss of already compromised airway with serious consequences. The greatest challenge during AFOI is to provide adequate sedation and analgesia while maintaining a patent airway and ensuring spontaneous ventilation. A wide variety of techniques are used mostly in combinations for airway anesthesia which include topical, intravenous (i.v.), or as airway nerve blocks. To achieve these conditions, various pharmacological agents alone or with combination with local anesthetics and nerve blocks are chosen. An ideal sedative drug for AFOI should provide adequate anxiolysis, amnesia with a low incidence of recall of the procedure. It should have analgesic properties too, to suppress the gag and cough, and be safe and easy to titrate with minimal respiratory and cardiovascular side effects. Airway nerve blocks are frequently used as they provide rapid and deep anesthesia. i.v. agents including benzodiazepines, opioids, ketamine, propofol, and dexmedetomidine have been used alone or in combination. Lignocaine is the most commonly used local anesthetic.
Dexmedetomidine is highly selective and specific alpha 2 adrenoreceptor agonist and has properties making it suitable for AFOI. In addition to hemodynamic stability and anxiolytic and analgesic properties, it leads to sedation while maintaining easy arousability. Dexmedetomidine demonstrates minimal respiratory depression even at higher doses and also decreases salivary secretions, which is desirable during AFOI. Fentanyl is used for the induction of general anesthesia to reduce pain and intubation response endotracheal tube (ETT) passage. Fentanyl belongs to an opioid group of family, which helps in reducing the pain by working on the μ type of opioid receptors. Opioids inhibit voltage-gated calcium channels and also activate inwardly rectifying potassium channels. Lee et al. have used fentanyl infusion with other agents as an analgesic for AFOI. AFOI can be associated with intense nociceptive stimulation, especially during passage of the ETT through the nose and the larynx. While pure sedatives provide anxiolysis and amnesia and may help to smooth the intubation process, they cannot substitute for adequate airway topicalization with a local anesthetic.
In “spray-as-you-go” (SAYGo) technique, a local anesthetic agent is sprayed along the path of the airway while advancing the fiber-optic bronchoscope (FOB). This can be done using an epidural catheter inserted through the side port of the FOB or syringe containing a local anesthetic drug. Airway nerve block is considered to be the gold standard for AFOI. The nerves blocked are, namely, glossopharyngeal, superior laryngeal, and recurrent laryngeal nerves, this helps in anesthetizing the entire upper airway till the carina. But sometimes, distorted anatomy, massive neck swelling, traumatic injury to head and neck, and local infection mandate us to think about alternate techniques of airway anesthesia without local nerve blocks.
Thus, this study was conducted to compare the endoscopic time, intubating condition, vocal cord position, cough severity, patient comfort during intubation, and postoperative satisfaction of patients receiving i.v. dexmedetomidine and SAYGo technique with 4% lignocaine versus i.v. fentanyl and transtracheal injection of 4% lignocaine for awake nasotracheal intubation with flexible videoscope. Novelty of our study was that 4% lignocaine was never used in any previous study for AFOI.
| Materials and Methods|| |
This prospective randomized single-blind study was followed as per the Institutional Ethical Committee (DMR/IMS.SH/SOA/180244/07.06.2019) guidelines. This research was done following the ethical principles for medical research involving human subjects in accordance with the Helsinki Declaration 2013 over a period of 8 months (July 1, 2019–February 29, 2020). Written informed consent was obtained from each patient for participation in the study and use of the data for research and educational purpose. Only the participants were blinded to the drug group. This study adhered to CONSORT guidelines (http://www.consort-statement.org).
Sample size calculation
In a pilot study done on ten patients each, the required sample size was calculated to be 40 patients to demonstrate a 30% difference in postoperative patient score with a power of 0.8 and Type 1 error of 0.05. To allow for study error, a total of 60 patients were included in the study.
Randomization and allocation concealment
Randomization was done into two equal Groups D and F, each of 30 with allocation ratio being 1:1 by using computer generated randomization list. The group sequence was concealed in sealed opaque envelopes which were on the day of surgery.
Inclusion criteria were sixty patients of age group from 18 to 65 years of both sexes, belonging to American Society of Anesthesiologists (ASA) physical status Class I and II posted for surgeries under general anesthesia at our institution with Malampatti Class I and II.
Patients who did not provide consent, with body mass index more than 30 kg.m2, had an allergy to any study drug, and hemodynamically unstable; pregnant patients; and patients with abnormal coagulation profile and ASA physical status Class III and IV were excluded from the surgery.
Group D received i.v. dexmedetomidine 1 μg.kg−1 intravenously over 10 min and 3 ml of 4% plain lignocaine as SAYGo. Group F received i.v. fentanyl 2 ug.kg−1 10 min and transtracheal injection 3 ml of 4% plain lignocaine.
A detailed history, physical examination, and routine investigations were done for all the patients. Patients who have met inclusion criteria were explained about the procedure. All the patients of both the study groups were advised to maintain nil per oral for 8 h before the surgery. The patients were connected to ASA physical status standard monitoring devices which included electrocardiography, pulse oximeter (SpO2), and a noninvasive blood pressure cuff in the operation theater. Baseline mean arterial pressure (MAP), heart rate (HR), and pulse oximetry (SpO2) were monitored. i.v. access was secured with an 18G cannula and i.v. fluid was started. All the patients were given nebulization with 2% lignocaine 2 ml and xylometazoline 0.1% nasal drops, two drops in each nostril were given. All the patients were premedicated with glycopyrrolate 0.004 mg.kg−1 i.v. and midazolam 0.05 mg.kg−1 i.v., ondansetron 0.08 mg.kg−1 i.v. and pantoprazole 40 mg i.v. Patients of Group D received dexmedetomidine 1 ug.kg−1 over 10 min i.v. and 3 ml of 4% lidocaine was instilled through fiber-optic videoscope as SAYGo. Group F patients received fentanyl 2 μg.kg−1 i.v. over 10 min along with 3 ml of 4% lidocaine as transtracheal block.
The patient was lying in the supine position. The fiber-optic flexible videoscope (AmbuR aScope™ 3 Regular 5.0/2.2) was checked for illumination and the more patent nostril was chosen for nasal fiber-optic intubation, the other nostril was used for oxygen insufflation. After desired sedation level as per Ramsay sedation score ≥2, a well-lubricated and sterile fiber-optic videoscope was introduced with appropriate size cuffed flexometallic ETT with an internal diameter of 8.0 or 7.0 mm (for males and females, respectively). The videoscope was passed through the glottic opening and after visualization of tracheal rings and the carina, the ETT was railroaded over the videoscope into the trachea and was secured 3–4 cm above the carina. The position of the ETT was further confirmed by chest auscultation and capnography and cuff inflated. Propofol 2 mg.kg−1 i.v. and vecuronium bromide 0.1 mg.kg−1 i.v. were used to induce general anesthesia and establish mechanical ventilation.
Any changes in the SpO2 <95% for more than 10 s were planned to be treated with supplemental oxygen. Any changes in MAP <20% of baseline were treated with i.v. fluids and ephedrine 6 mg i.v. in titrated doses. Any changes in heart rate <60/min were treated with atropine (0.02 mg.kg‒1) i.v. Postoperative patient satisfaction was assessed the day after surgery.
Primary outcomes observed were endoscopic time (time taken from the introduction of fiber-optic videoscope tip through the nostril till visualization of the glottis), intubating condition, vocal cord position, cough severity, comfort during intubation, and postoperative patient satisfaction. Scoring system is shown in [Table 1].
Secondary outcomes observed were postintubation heart rate, MAP, pulse oximetry (SpO2), and adverse effects such as laryngospasm, bronchospasm, desaturation, and postoperative sore throat.
Statistical analysis was done using the Statistical package for the social sciences, version 23, SPSS inc., Chicago, Ilionois, USA. Shapiro–Wilk test was used for test for normality to distribute numeric data into parametric and nonparametric. Parametric data were compared independent t-test and nonparametric data using Mann–Whitney U-test. Categorical data were compared between two groups using Chi-square test or Fisher's exact test. Numerical data were expressed as mean and standard deviation and categorical data as numbers and percentage. All analyses were two tailed and the results were discussed on a 5% level of significance, i.e., P ≤ 0.05 was considered statistically significant.
| Results|| |
All the 60 patients enrolled in the study were analyzed [Figure 1]. Demographic profile was comparable in terms of age, sex, weight, and ASA physical status in both fentanyl and dexmedetomidine groups [Table 2]. Baseline heart rate, MAP, and oxygen saturation were found to be statistically insignificant between the groups [Table 3]. In Group F (n = 30), five patients had the best intubating conditions score 1 (optimal condition), 23 patients had the intubating conditions score 2 (sub-optimal) two patients had intubating conditions score 3 (difficult conditions) In Group D (n = 30), 15 patients had the best intubating conditions score (score 1), 15 patients had intubating conditions (score 2), no patients had the intubating conditions (score 3), and 50% of the patients had the best intubating condition score of 1, whereas 16.7% of the patients in Group F had intubating conditions score of 1. P = 0.008 which is <0.05 is statistically significant. Thus, the intubating conditions were significantly favorable in Group D than Group F [Table 4].
|Table 3: Baseline heartrate, mean arterial pressure and oxygen saturation|
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[Table 5] shows vocal cord position in which 63.3% of patients in Group D had glottis open, whereas only 30% of patients had glottis open (P < 0.05). In Group F (n = 30), three patients had no cough (score 1), 16 patients had slight cough (score 2), and 11 patients had verbal objections (score 3). In Group D (n = 30), six patients had no cough (score 1), 21 patients had slight cough (score 2), and three patients had verbal objection (score 3). No patients from both the groups had severe cough (score >4 cough in sequence), 53.3% of the patients in Group F had cough score 2, and 36.7% of patients had cough score 3, while 56.8% of the patients in Group D had cough score 2 and only 10% of patients had cough score 3. Cough severity score was significantly lower in dexmedetomidine [Table 6]. The comfort during intubation was significantly favorable in Group D than Group F, as shown in [Table 7]. Only three patients had the score 1 (no reaction), 12 patients had score 2 (grimacing), and 15 patients had score 3 (verbal objection) in Group F. In Group D (n = 30), 13 patients had score 1 (no reaction) which is the best score for comfort of patient during intubation, 13 patients had score 2 (grimacing), and four patients score 3 (verbal objection). No patients from both the groups had score 4 which is defensive movements by patients during intubation. About 81.3% of the patients in Group D had the best comfort during intubation with score of 1, whereas only 18.8% of the patients in Group F had a score of 1. P = 0.002 is statistically significant.
In Group F, five patients had excellent (score 1), while in Group D, eight patients had excellent (score 1) postoperative satisfaction. In Group F, 11 patients (36.7%) had good (score 2) postoperative satisfaction, whereas 20 patients (66.7%) had good (score 2) postoperative satisfaction. In Group F, 14 patients had fair (score 3), while in Group D, only two patients. P = 0.02 is statistically significant [Table 8]. The endoscopic time was statistically more in Group D as compared to Group F [Table 9]. Postintubation heart rate and MAP were significantly low in Group D as compared to Group F. The mean postintubation SpO2 for Group F was 97.1% and the mean of postintubation SpO2 for Group D was 98.23%. P = 0.01 which is < 0.05 is statistically significant [Table 10]. None of the patients had any adverse effects such as laryngospasm, bronchospasm, desaturation, or postoperative sore throat.
|Table 10: Postintubation heartrate, mean arterial pressure and oxygen saturation|
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| Discussion|| |
The invention of the flexible FOB in 1966 by Dr. ShigetoIkeda and endotracheal intubation by Dr. Peter Murphy in 1967 made a revolution in airway management., Regional anesthesia for the airway along with i.v. sedation makes AFOI comfortable and acceptable for patients but has also afforded anesthesiologists better control over intubation conditions. Nebulization of local anesthetics is another promising technique in which the airway is anesthetized completely without the need for multiple painful injections. It deposits fine droplets of local anesthetic directly over the mucosa, thus anesthetizing it and obviating the necessity for multiple painful injections. Furthermore, this technique requires less detailed knowledge of anatomy, less specialist skills, and fewer experience; it also can be utilized in cases of massive neck swelling where nerve block cannot be performed. However, it has some disadvantages including the need for large doses of local anesthetic (due to wastage during administration), a better chance of failure, and a delayed onset of action. As a cornerstone in managing difficult airways, the FOB is often used to apply local anesthetics to the airway in a “SAYGo” method. This method can provide flexibility in selectively anesthetizing the airway and is a suitable choice for most awake intubations. Adequate airway topical anesthesia generally determines the ease and comfort of AFOI. Airway topical anesthesia was achieved with the SAYGo technique previously described. The goals for the drug administration are patient comfort, cooperation, amnesia, hemodynamic stability, and blunt airway reflexes and maintain a patent airway with spontaneous ventilation.
Dexmedetomidine is a highly selective, centrally acting α-2 agonist. It acts on presynaptic α-2 receptors to supply feedback causing less neurotransmitter (norepinephrine and epinephrine) available at postsynaptic α-1 receptors. It produces hypnosis, amnesia analgesia, anxiolysis, sympatholysis, and antisialagogue effects, all of which are desirable during AFOI. Dexmedetomidine induces sedation involving activation of endogenous sleep-promoting pathway through the postsynaptic α-2 receptors within the locus ceruleus, which modulates wakefulness. It is of interest because it possesses sedative, anxiolytic, analgesic, and sympatholytic properties during awake intubation without affecting the respiratory function. The feasibility of dexmedetomidine has been recently studied either as a sole sedative agent or as an adjuvant during AFOI. Fentanyl is a phenylpiperidine derivative of synthetic opioids, which provides mild sedation and analgesia along with hemodynamic stability, which are beneficial for AFOI, but there is a risk of respiratory depression, nausea, vomiting, and chest wall rigidity. Sometimes due to variation in anatomy, nerve blocks of airway become impossible. Dexmedetomidine has been considered useful for AFOI for its sedative, anxiolytic, analgesic, sympatholytic properties, and reducing patient's discomfort, without depressing respiratory function and having a negligible impact on the cardiovascular system. SAYGo technique also provides adequate supraglottic and infraglottic anesthesia. Hence, we conducted this study to evaluate the efficacy of dexmedetomidine and SAYGo method for AFOI in comparison to fentanyl and transtracheal block.
No failure of intubation was there in either group. Intubating condition was significantly (P < 0.05) better in dexmedetomidine group as compared to fentanyl group. None of the patient in Group D was found to have difficult intubating conditions. Hence, i.v. dexmedetomidine along with SAYGo with 4% lignocaine provides better tolerance than i.v. fentanyl with 4% of lignocaine transtracheal block. Chu et al. had observed better tolerance of endotracheal intubation without upper airway obstruction and respiratory depression in the dexmedetomidine group (1 ug.kg‒1) compared with the fentanyl group (1 ug.kg‒1). In a study, 56 patients undergoing cervical fixation were divided into two groups of 26 patients for AFOI. The test group received dexmedetomidine infusion and the control group received normal saline. They reported that the group receiving dexmedetomidine infusion in addition to topical anesthesia during AFOI remained more comfortable than the group with airway block alone. Vocal cord position was more optimal for intubation in Group D. Glottis was completely relaxed in 67.9% of patients with dexmedetomidine group as compared to 32.1% in fentanyl group. Tsai et al. found that dexmedetomidine group had more favorable intubation score for vocal cord movement than the propofol group. Patient comfort was assessed by cough severity and comfort during intubation. Cough score of ≤2 was considered to be ideal for awake videoscopic intubation. Group D showed less cough score than Group F (P < 0.05). Comfort during intubation was significantly better with dexmedetomidine and SAYGo with lignocaine as compared to fentanyl and transtracheal block (P = 0.002). Bergese et al. noted that dexmedetomidine at 1 μg.kg‒1 bolus was safe and beneficial for patients undergoing AFOI even without airway nerve block or topical anesthesia. Sayeed et al. observed that comfort scores were comparable in both the groups which differed from our results. Agrawal et al. also found similar comfort levels in the two groups. In a randomized double-blind study, the authors compare the effectiveness of sufentanil with midazolam and dexmedetomidine with midazolam for conscious sedation for AFOI together with a “SAYGo” method. In this study, the results were found to be comparable for the two groups in terms of patient's tolerance and intubating conditions.
Endoscopic time is described as the time taken from the introduction of fiber-optic videoscope tip through the nostril till visualization of the glottis. It was significantly more in Group D than Group F. SAYGo method requires time for topical absorption of local anesthetics. 2%–4% lidocaine applied to the airway mucosa begins to produce topical anesthesia in about 1 min. Gupta et al. who reported a mean intubation time of 123 (46.7) s in a nerve block group and 200.4 (72.4) s during a nebulization group (P = 0.047). However, Reasoner et al. found no significant difference in intubation time between nerve block and topical anesthesia groups, and the intubation time was longer than in any other study. Postoperative patient satisfaction was significantly better with Group D in our study. About 61.5% of patients were extremely satisfied with i.v. dexmedetomidine and SAYGo technique as compared with 38.5% in fentanyl group and transtracheal block. Dexmedetomidine being sedative, anxiolytic, analgesic, and amnestic provides better patient comfort and satisfaction. Mondal et al. observed higher sedation scores with dexmedetomidine group than fentanyl group with better tolerance for AFOI.
Our study suggests that saturation is better maintained with dexmedetomidine, as mean SpO2 was significantly more in Group D. Dexmedetomidine induces conscious sedation by activating the endogenous sleep-promoting pathway. Patients sedated with dexmedetomidine are awakened more easily when stimulated than those sedated with midazolam; in addition, they experience little respiratory depression., In a systematic review, He et al. have shown that dexmedetomidine reduces participant's discomfort with no significant differences in airway obstruction, low oxygen levels, or management of cardiovascular adverse events noted during AFOI compared with control groups. Bailey et al. observed that fentanyl alone produced hypoxemia in half of the subjects and significant depression of the ventilatory response to carbon dioxide but did not produce apnea. Mondal et al. also observed that the incidence of desaturation was less in dexmedetomidine group (four patients) than fentanyl Group F (25 patients). Ryu et al. also showed less incidence of desaturation with dexmedetomidine than remifentanil.
In our study, there was significant attenuation of postintubation hemodynamic response in Group D as compared to Group F. Both mean heart rate (P = 0.001) and MAP (P = 0.03) were decreased in patients receiving i.v. dexmedetomidine and SAYGo technique following intubation as compared to i.v. fentanyl and transtracheal block. This can be attributed to dexmedetomidine causing decreased noradrenaline release, decreased centrally mediated sympathetic tone, and increased vagal activity. Also maybe, SAYGo technique with 2% lignocaine provides adequate topical anesthesia of the airway. Mondal et al. also observed that patients of dexmedetomidine group showed better hemodynamic stability. Initial HR and MAP were similar in both groups. A study reported unaltered hemodynamics even in higher doses of dexmedetomidine infusion. The limitation of our study is being a single-blind study, the chance of observational bias is there. Furthermore, tolerance to intubation of each individual patient may differ, adding bias to the study.
| Conclusion|| |
Injection dexmedetomidine (1 ug.kg‒1 over 10 min) i.v. with SAYGo technique is effective than injection fentanyl (2 ug.kg‒1 over 10 min) i.v. with transtracheal block for awake fiber-optic videoscopic intubation in terms of intubating conditions, vocal cord position, cough severity, comfort during intubation, and postoperative patient satisfaction with significant attenuation of postintubation hemodynamic response and better preservation of respiration though endoscopic time is more.
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Conflicts of interest
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10]