Efficacy of Nebulized Dexmedetomidine and Lignocaine Inhalation versus Lignocaine Alone as Premedication for Flexible Fiber-optic Bronchoscopy under Sedation: A Randomized Comparative Study

Abstract

Introduction:

Airway management is an integral part of general anesthesia, allowing ventilation and oxygenation and working as a mode for delivering anesthetic gases. Awake fiber-optic-guided intubation is an essential component of airway management in difficult cases. We aim to study the benefits of nebulized dexmedetomidine with lignocaine over lignocaine alone for anesthetizing the airway for flexible fiber-optic bronchoscopy.

Materials and Methods:

In the study, after written informed consent, 50 patients were randomly allocated into two equal groups of 25 each. The intervention group received dexmedetomidine with lignocaine nebulization, while the control group received lignocaine nebulization alone. Baseline pulse rate, blood pressure, and, at regular intervals, cough, sedation, and pain scores were recorded along with the patient satisfaction score. Parametric data were analyzed by the Student’s t-test, while nonparametric data were analyzed by the Wilcoxon Mann–Whitney U test.

Results:

Out of a total of 54 patients, 4 patients did not give consent to participate in the study. The demographic profile was comparable in both groups. The pulse rate was comparable in both groups throughout the procedure; however, 10 min after the procedure, the pulse rate in the lignocaine group was (mean ± standard deviation) 114.2 ± 11.52, while in the intervention group, it was 87.32 ± 7.24 with a P = 0.027. The mean blood pressure was comparable throughout the procedure. The cough score yielded a Z-score of −5.12 and a P < 0.00001 favoring the dexmedetomidine group. Similarly, Richmond agitation-sedation score and Visual Analog Scale (VAS) also favored the intervention group, with P < 0.00054 and P < 0.00001 in RASS and VAS, respectively. Patient satisfaction score analysis found a Z-score of −5.29 and a P < 0.00001.

Conclusion:

The overall results favored dexmedetomidine with lignocaine nebulization over lignocaine alone for anesthetizing airways for flexible fiber-optic bronchoscopy.

INTRODUCTION

Airway management is an integral part of general anesthesia, allowing ventilation and oxygenation, and working as a mode for delivering anesthetic gases. Different approaches to achieve airway management have progressed from blind intubation to direct and video laryngoscopy and intubating a fiber-optic bronchoscope.

The intubating fiber-optic bronchoscope was first described in 1967 by Murphy.[1] Fiber-optic intubation is an effective technique for establishing airway access in both anticipated and unanticipated difficult airways. It has become a mainstay of difficult airway management in awake, sedated, and anesthetized patients.

Awake fiber-optic guided intubation causes discomfort to the patients; thus, it is essential to anesthetize the airway sufficiently before performing fiber-optic intubation to ensure the patient’s comfort and cooperation. Adequate anesthesia prevents cough and gag reflexes, increases patient cooperation, and prevents undesirable hemodynamic changes. There are various techniques of airway block, such as transtracheal block, superior laryngeal nerve block, glossopharyngeal nerve block, gargling with local anesthetics, spray as you go, using spraying of local anesthetics through the fiber-optic channel, and nebulization.

Nebulization with local anesthetics is also a technique used for achieving airway anesthesia.[2] As the patient nebulizes, the drug gets deposited in the form of mists over the buccal mucosa, thereby anesthetizing upper airway structures such as the nasopharynx, oropharynx, and larynx.[3] Nebulization is a simple technique that only requires a minimum of skills and knowledge of the anatomy and is a time-saving process. Furthermore, with this technique, the fear of needle injections and pain is lowered. A randomized controlled trial by Gu et al. concluded that nebulized dexmedetomidine for flexible fiber-optic bronchoscopy significantly reduces the incidence of cough and shortens recovery time.[4]

In this study, we compared the two nebulization techniques, namely, nebulization with lignocaine alone and nebulization with lignocaine with dexmedetomidine, in premedication for awake fiber-optic intubation.

MATERIALS AND METHODS

The study proposal obtained clearance from the Institutional Ethics Committee, followed by registration in the Clinical Trial Registry of India (CTRI no. CTRI/2022/03/041532) prospectively. The study adhered to the World Medical Association Declaration of Helsinki on ethical principles for medical research involving human subjects. The study followed CONSORT 2010 updated guidelines for reporting parallel group randomized trials. The CONSORT flow diagram is shown in Figure 1, and the detailed consort checklist is in the supplementary file. Informed consents were taken from study participants before recruitment.

Figure 1.

CONSORT flow diagram

The study was designed as a randomized controlled trial after taking informed consent from the patient. The study question was: Is dexmedetomidine added to lidocaine nebulization in the airway before flexible bronchoscopy beneficial compared to lidocaine nebulization without dexmedetomidine? Based on this question frame, the primary objective was to determine the efficacy of nebulization with dexmedetomidine and lignocaine over lignocaine alone, along with sedation, for flexible fiber-optic bronchoscopy. The secondary objective includes a comparison of patient comfort before and after bronchoscopy, postprocedural patient vitals, including pulse rate, systolic blood pressure, mean arterial pressure, secretions, coughing, the Richmond agitation-sedation score (RASS), and a comparison of the requirements of rescue analgesia, sedatives, and pain score after the procedure to minimize the need for rescue induction by laryngoscopy and to achieve postprocedural patient satisfaction.

Based on the previous data on fiber-optic intubation in our institution, the sample size was calculated with a type 1 error of 0.05 and a power of study of 0.80 with outcome percentages in two treatment arms of 33% and 73%, respectively, the sample size was calculated as 46. Taking attrition of 10% the corrected sample size came out to be 50, which is 25 in each group. The calculated sample size is 50, which was divided into two groups of 25 each. Patients were randomized into two groups (25 each) by computer-generated random numbers. The random allocation sequence was disclosed at the time of the procedure. Group D patients were nebulized with a mixture of 4 mL of 4% lignocaine and injection dexmedetomidine (1 mg/kg). Group L patients were nebulized with a mixture of 4 mL of 4% lignocaine mixed with saline. The volume of both solutions was kept constant at 6 ml. Inclusion criteria for the study were ASA physical status grades I and II, belonging to the age range of 18–50 years, and posted for elective surgery under general anesthesia who required orotracheal or nasotracheal intubation. Those patients who had a history of bleeding diathesis, loss of consciousness, cervical spine instability, obesity with a body mass index >30 kg/m², and anticipated difficult intubation on examination were excluded from the study. The data that were collected were pulse rate, mean arterial pressure, and oxygen saturation at baseline (5 min and 10 min). Any episode of coughing or gag reflex during the procedure and the sedation score were recorded. After 6 h of extubation, a Visual Analog Scale (VAS) of 0–10 was used to determine the pain score, and the patient satisfaction score was recorded.

Statistical analysis was performed using SPSS 20 software (IBM SPSS Statistics version 20.0.2.0 (20), Chicago, IL, USA). Continuous variables were expressed as means ± standard deviation, and categorical variables were expressed as proportions. A Student’s t-test was used to analyze parametric data. For nonparametric variables, the Wilcoxon-Mann–Whitney test was performed. P < 0.05 was considered statistically significant.

RESULTS

Out of a total of 54 patients, 4 patients did not give consent to participate in the study. The maximum number of patients in Group D is in the age group 31–40 years (n = 10, 40%), and in Group L, both age groups 31–40 years and 41–50 years had a similar maximum number of patients (n = 10, 40%). The age distribution in different age groups was not comparable, as the P = 0.844 (>0.05%). The demographic profile is shown in Table 1.

Table 1.

Demographic profile

Age (years)	Group-D (n=25), n (%)	Group-L (n=25), n (%)
18–30	6 (24)	5 (20)
31–40	10 (40)	10 (40)
41–50	9 (36)	10 (40)
Mean±SD	37.8±8.83	37.4±8.31
P	0.844

SD=Standard deviation

A comparison of pulse rates at various intervals in Group D and Group L is shown in Table 2.

Table 2.

Comparison of pulse rate between Group L and Group D

Pulse rate in beats per min	Group-L (mean±SD)	Group-D (mean±SD)	P
Baseline	90.44±22.47	84.6±13.95	0.023
At start of procedure	94.92±16.45	88.64±18.82	0.51
At 5 min	104.92±11.78	88.4±15.64	0.17
At 10 min	114.2±11.52	87.32±7.24	0.027

SD=Standard deviation

The mean atrial pressure did not show any significant variation between the groups, as shown in Table 3.

Table 3.

Comparison of mean atrial pressure at various intervals in Groups D and L

	Group-L	Group-D	P
Baseline	82.56±10.35	75.72±12.07	0.45
At start of procedure	88.04±12.05	76.92±12.25	0.93
At 5 min	95.8±11.06	78.44±10.50	0.80
At 10 min	94.96±10.80	77.92±10.92	0.95

Cough score: The cough scores were measured as no cough to severe cough depending on episodes of cough and scores ranging from 1 to 4, as shown in Table 4. The data analyzed by applying the Mann–Whitney U-test obtained a highly significant trend toward the use of dexmedetomidine in such patients.

Table 4.

Cough score and analysis

Score	Cough	Episodes of cough
1	No cough
2	Mild	≤2 cough
3	Moderate	3–5 cough
4	Severe	>5 cough
	Group-L	Group-D
Sum of ranks	368.5	856.5
Mean of ranks	14.74	35.69
Expected sum of ranks	625	600
Expected mean of ranks	25	25
Expected U value	300	300

On applying the Mann–Whitney U-test to the cough score data between Groups D and L.

The U value is 43.5. The Z score is − 5.12. The P < 0.00001. The result is significant at P < 0.05.

Richmond agitation-sedation score: RASS is a 10-point score ranging from +4 “combative” to −5 “unarousable.”[5] The analysis of the score is shown in Table 5, with highly significant results for Group D.

Table 5.

Richmond agitation-sedation score analysis of Group D and Group L

	Group-L	Group-D
Sum of ranks	451.5	773.5
Mean of ranks	18.06	32.23
Expected sum of ranks	600	625
Expected mean of ranks	25	25
U	473.5	126.5
Expected U value	300	300

On applying Mann–Whitney U-test to data of sedation score between Group D and Group L, the U value is 126.5. The Z-score is −3.46. The P < 0.00054. The result is significant at P < 0.05.

Patient satisfaction score: The patient satisfaction score is highly significant toward Group D, as shown in Table 6.

Table 6.

Patient satisfaction score between the groups

	Group-L	Group-D
Sum of ranks	360	865
Mean of ranks	14.4	36.04
Expected sum of ranks	625	600
Expected mean of ranks	25	25
Expected U value	565	300

On applying the Mann–Whitney U-test to the data of the sedation score between Groups D and L, the U value is 35, and the Z-score is −5.29. The P < 0.00001. The result is significant at P < 0.05.

VAS score: The VAS analyzed for Groups D and L is shown in Table 7. Again, results are significant in favor of the use of dexmedetomidine for nebulization with lignocaine.

Table 7.

Analysis of Visual Analog Scale in Group D and Group L

	Group-L	Group-D
Sum of ranks	335	890
Mean of ranks	13.4	37.04
Expected sum of ranks	625	600
Expected mean of ranks	25	25
Expected U value	590	300

On applying the Mann–Whitney U-test to the VAS score data between Groups D and L, the U value is 10. The Z score is −5.79. The P < 0.00001. The result is significant at P < 0.05.

DISCUSSION

Innovations and developments in anesthesia have resulted in remarkable improvements in various aspects of airway management. A flexible fiber-optic bronchoscope was invented in 1996 by Dr. Shigeto Ikeda, and Dr. Peter Murphy used it for endotracheal intubation in 1967. Hassanein A et al used lignocaine nebulisation technique for fiberoptic bronchoscopy.[6]

Different airway anesthesia techniques have been compared by several authors. In 2000, Kundra et al. compared nebulized lignocaine 4% with a combined regional nerve block for awake fiber-optic nasotracheal intubation in 48 adult patients and found that combined regional blocks with nebulization were superior to blocks alone.[7]

In our study, both groups showed a demographic similarity. The mean duration of surgery was not significant. VAS scores were significantly lower in Group D compared to Group L, with a P < 0.05. The Richmond Agitation-Sedation Scale was significantly higher in Group D compared to Group L, with P < 0.05. Postprocedure patient satisfaction was higher in Group D compared with Group L with a P < 0.05, better hemodynamic stability, and lower VAS scores in group dexmedetomidine with lignocaine as compared to group lidocaine alone.

The study by Gu et al. suggested that nebulized dexmedetomidine–lidocaine inhalation as a premedication for flexible bronchoscopy was well tolerated during bronchoscopies performed under moderate sedation and was associated with a reduced incidence of moderate to severe coughing, a shorter recovery time, and reduced vasoconstrictor consumption.[4] In our study, we compared nebulized dexmedetomidine–lidocaine with nebulized lidocaine alone and got similar results for cough with a z-score of −5.12 and a P < 0.00001. Nebulized dexmedetomidine has greater bioavailability in the oropharynx, thus resulting in direct action with fewer adverse effects.[8]

Nebulization has not been recommended as a technique for delivering lidocaine to the airways, as there is a lack of definite evidence of cough suppression with lignocaine. However, studies have shown nebulized lignocaine provides sufficient anesthesia for diagnostic transnasal tracheoscopy. In the study conducted by Dreher et al., nebulized versus standard local application of lidocaine during flexible bronchoscopy suggested that endobronchial administration of lidocaine during bronchoscopy through nebulizer was found to be well tolerated and safe and was associated with reduced lidocaine and fentanyl dosages.[9]

In a similar study conducted by Müller et al., nebulization versus standard application for topical anesthesia during flexible bronchoscopy under moderate sedation suggested endobronchial administration through nebulization was well tolerated during bronchoscopies under moderate sedation and associated with better airway anesthesia, better oxygenation, and reduced lidocaine consumption.[10]

In our study, we used nebulization with 4% lidocaine and nebulization with lidocaine at 4% along with dexmedetomidine at 1 µg/kg. In our study, there was one failure of intubation in Group L, in which rescue intubation by direct laryngoscope was done. In our study, the intubating conditions were better in Group D compared to Group L, similar to the study of Gu et al.[4]

We compared patient comfort between the study groups, cough severity, patient satisfaction, sedation, and VAS scores. Patient comfort was higher in the group with dexmedetomidine. The VAS score was lower in Group D. Similarly, RASS was in favor of Group D, with a Z-score of −3.46 and a P = 0.00054. Similar findings were seen in a study done by Gaikawad et al.[11] The hemodynamic parameters were more stable in the dexmedetomidine group. No patient required any pharmacological intervention in any group.

In our study, we found that the oxygen saturation was comparable between both groups. All patients received supplemental oxygen through the working channel of the fiber-optic bronchoscope.

In our study, patient satisfaction scores recorded 6 h after extubation were higher in group dexmedetomidine than in group lidocaine. No other side effects such as bradycardia, arrhythmia, bronchospasm, or seizures due to lignocaine toxicity were observed in either group.

In conclusion, our study revealed that airway anesthesia using nebulization with dexmedetomidine and lidocaine inhalation can be effectively used for fiber-optic bronchoscopy under sedation in terms of patient comfort. Nebulization is a feasible process, and no complications related to nebulization have been observed.

We believe that the limitation of this study is that the endpoints could have been more elaborated, hence we were unable to detect adverse reactions. The optimal concentration of dexmedetomidine and lidocaine could not be determined. Our study did not include patients with difficult airways; hence, the results cannot be directly extrapolated to patients with difficult airways or the use of fiber-optics for difficult airways.

CONCLUSION

In our study, we compared the quality of airway anesthesia using cough scores, sedation, pain, and patient comfort and satisfaction. Nebulization with dexmedetomidine and lignocaine was found to be more efficacious compared to lignocaine alone.

Nebulized dexmedetomidine–lidocaine inhalation as a premedication for flexible fiber-optic bronchoscopy can be used effectively for bronchoscopy and intubation under moderate sedation. Nebulization of local anesthetics prevents multiple injections and does not require expert hands. It is easy to administer anesthetic agents through nebulization, which has greater bioavailability and is more patient-friendly. Local anesthetics fortified with dexmedetomidine provide better sedation, a lesser cough, and lower pain scores.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.