Comparison of the Effect of Left Head Rotation versus the Direct Epiglottis Lifting Technique on Glottic View during C-MAC Videolaryngoscopy in Patients with Difficult Airway

Abstract

Background and Aims:

Optimal glottic visualization is fundamental for safe intubation in patients with difficult airways. We aimed to compare the effectiveness of left head rotation (LeHeR) versus the direct epiglottis lifting technique using the C-MAC D-blade videolaryngoscope in improving glottic view during intubation in adult patients with difficult airways.

Methods:

In this prospective, randomized, double-blinded trial, 60 adult patients were allocated equally to receive LeHeR (Group L) or direct epiglottis lifting (Group E) technique for intubation. After standardized induction, videolaryngoscopy with C-MAC D blade was done, and the best glottic view was captured. The second glottic image was taken following LeHeR in Group L and direct epiglottis lifting in Group E. Percentage of glottic opening (POGO) in both images was compared later by an anonymized anesthesiologist. Change in POGO, ease and time to intubation, hemodynamic responses, and desaturation < 95% were compared in both groups.

Results:

Demographics and baseline airway variables were comparable. Both maneuvers significantly improved intragroup POGO scores (P ≤ 0.001). The median second POGO was higher with epiglottis lifting than LeHeR technique (100 [interquartile range 75–100] vs. 75 [75–100], P = 0.03). Improvement in glottic view occurred in 96.7% of patients in Group E versus 63.3% in Group L (P = 0.002). Time to intubation (33 ± 12 vs. 31 ± 10 s), ease of intubation, hemodynamics, and incidence of desaturation were comparable.

Conclusion:

Direct epiglottis lifting with C-MAC videolaryngoscope D blade provided significantly improved glottic visualization compared to LeHeR with comparable intubation time in patients with difficult airway.

INTRODUCTION

Optimal glottic visualization is crucial for successful tracheal intubation, especially in challenging airways, where inadequate views can lead to intubation delays and desaturation.[1,2] While video laryngoscopy has improved airway management in patients with difficult airways, glottic visualization could remain inadequate in some cases.[,4,5,6] To overcome this, simple maneuvers such as backward, upward, rightward pressure maneuver,[7,8] head-and-neck elevation beyond the sniffing position,[9] left head rotation (LeHeR) position,[10,11] and direct epiglottis lifting techniques[12] have been recommended as techniques with potential benefits. However, a direct comparison of the usefulness of the LeHeR position and the direct epiglottis lifting technique on glottic view during C-MAC videolaryngoscopy in patients with difficult airways remains an unexplored area in the existing literature.

The primary objective of the present study was a comparison of improvement in glottic view as assessed with the percentage of glottic opening (POGO) score during indirect laryngoscopy using C-MAC video laryngoscope in patients with difficult airway in LeHeR position versus direct epiglottis lifting technique. The secondary objectives included assessment of ease of intubation, time taken for intubation, use of bougie, need for external neck manipulation or cuff inflation-deflation for proper alignment of the endotracheal tube to glottis, hemodynamic responses during intubation, and incidence of desaturation to <95% in both groups.

METHODS

The study was a prospective randomized, double-blinded trial, which was conducted after obtaining ethical committee clearance certificate (IEC-AIMS-2025-ANES-091 dated May 7, 2025) and registering in Clinical Trial Registry India (CTRI/2025/05/086843). Randomization was done using computer-generated random sequence of numbers. Allocation was concealed using opaque sealed envelopes. The study procedures were conformed to the Declaration of Helsinki (2013), and written informed consent was obtained from all participants, which explicitly covered the use of their anonymized clinical data for research and educational purposes.

There were two groups of patients, Group L and Group E. Following a detailed preanesthesia checkup, the patients were kept fasting 6 h for solids and 2 h for clear fluids. In the theater, standard preinduction monitors were attached. All patients received a standardized anesthesia care. All patients were given glycopyrrolate 0.2 mg, midazolam 2 mg, fentanyl 2 µg/kg intravenously, and were induced with propofol 1.5–2 mg/kg till the loss of response to verbal commands. Suxamethonium 2 mg/kg was given after ensuring mask ventilation. After 1 min, the more patent nose was decongested with oxymetazoline drops, and dollops of lignocaine jelly were applied. Indirect laryngoscopy was performed using C-MAC video laryngoscope D blade with the head in the sniffing position. An image of the best glottic view was taken in this position in both groups. The patients with a 100% POGO score were excluded from the study. In Group L, the patient’s head was then rotated to 45° to the left side and the image of the best glottic view was captured. In Group E, following 1^st laryngoscopy, the laryngoscope blade was advanced to the undersurface of the epiglottis. The epiglottis was then directly lifted with the laryngoscope blade, and the image of the best glottic view was taken. Each patient had two images of the glottis, which were stored in the C-MAC monitor.

The patients were then nasally intubated with an appropriately sized nasal Ring–Adair–Elwyn tube. Any difficulty in aligning the tube with glottic opening was managed with external neck manipulation, cuff inflation-deflation, or with the use of Magill’s forceps in that order. Correct tracheal placement of the endotracheal tube was confirmed with the appearance of regular end-tidal carbon dioxide waveforms. Anesthesia was maintained with isoflurane 1%–1.5% in an air oxygen mixture with positive pressure ventilation and intermittent muscle relaxants and supplemental opioids.

All intubations were performed by anesthesiologists with more than 3 years of experience in videolaryngoscope-aided nasal intubations. Heart rate and mean arterial pressure were recorded before and after induction, 1, 3, 5, and 10 min after intubation. The ease of intubation was noted as easy, moderate, difficult, and unattainable. Patients with failed intubation were intubated with a hybrid technique using a fiberoptic bronchoscope.

After data collection, the images of the glottic opening of each patient in pairs were transferred from the C-MAC monitor to a laptop and numbered as the first image and the second image. The patents were anonymized by assigning a unique, false number to each patient. The sequence of the pair of images was randomized to further prevent the assessor from identifying the group from which the pair of images originated. A single, experienced anesthesiologist, who was blinded to the group allocation, independently assessed all glottic images, and the following parameters were noted such as initial POGO score, POGO score in the second image, whether there was an improvement or not, and if yes, the degree of improvement. A separate key was used to decode the false numbers and link the assessments back to the original patient data after the entire assessment process was complete.

All data are presented as mean and standard deviation, or as frequency and percentage, as applicable. For demographic and baseline airway characteristics, continuous variables were compared between the two groups using the independent samples t-test. Categorical variables were analyzed with the Chi-square test or Fisher’s exact test, as appropriate. For intragroup comparisons of POGO scores, the Wilcoxon signed-rank test was utilized, while the Mann–Whitney U test was used for intergroup comparisons. A P < 0.05 was considered statistically significant. Statistical analysis was performed using a commercially available statistical software package (SPSS version 25.0, IBM Corp., Armonk, NY, USA).

RESULTS

Data from sixty patients were analyzed [Figure 1]. There were no statistically significant differences between Group L and Group E for age, Body Mass Index, gender distribution, or American Society of Anesthesiologists Physical Status score [Table 1]. No significant differences were found between the groups for baseline airway parameters, which included mouth opening, thyromental distance, Mallampati score, and head extension [P > 0.05, Table 2].

Figure 1.

CONSORT flow diagram

Table 1.

Comparison of demographics, and American Society of Anesthesiologists Physical Status

Variable	Group L, mean±SD	Group E, mean±SD	P
Age (years)	53.93±17.21	57.93±17.91	0.290
BMI	24.82±4.42	23.72±4.15	0.324
Male	20±66.7	15±50	0.190
Female	10±33.3	15±50
ASA PS 2	11±36.7	20±66.7	0.796
ASA PS 3	19±63.3	10±33.3

ASA PS=American Society of Anesthesiologists Physical Status, BMI=Body mass index, SD=Standard deviation

Table 2.

Comparison of mouth opening, thyromental distance, Mallampati score, and head extension

Variable	Group L, mean±SD	Group E, mean±SD	P
Mouth opening (cm)	2.58±0.52	2.50±0.49	0.515
TMD (cm)	6.19±0.27	6.25±0.25	0.383
MP 3	17 (56.7)	17 (56.7)	1.00
MP 4	13 (43.3)	13 (43.3)
Normal head extension	28 (93.3)	27 (90.0)	0.640
Restricted head extension	2 (6.7)	3 (10.0)

TDM=Thyromental distance, MP=Mallampati, SD=Standard deviation

The mean time to intubate was 30.63 ± 10.05 s for Group L and 33.03 ± 11.87 s for Group E, a difference that was not statistically significant (P = 0.402). The ease of intubation also showed no significant difference (P = 0.426). However, a significant difference was observed in the percentage of patients with an improvement in glottic opening. This was noted in 96.7% of patients in Group E versus 63.3% in Group L [P = 0.002, Table 3].

Table 3.

Comparison of time to intubate, ease of intubation, and percentage of patients with improvement of glottic opening

Variable	Group L, mean±SD	Group E, mean±SD	P
Time to intubate (s)	30.63±10.05	33.03±11.87	0.402
Ease of intubation
Easy	20 (66.7)	17 (56.7)	0.426
Moderate	10 (33.3)	13 (43.3)
Comparison of percentage of patients with improvement of glottic opening
Yes	19 (63.3)	29 (96.7)	0.002
No	11 (36.7)	1 (3.3)

SD=Standard deviation

Intragroup POGO score analysis showed a statistically significant improvement in POGO scores in both Group L and Group E (P = 0.001 and P < 0.001, respectively). The intergroup comparison showed no significant difference for the first POGO score (P = 0.87), but a statistically significant difference for the second POGO score (P = 0.03), which was higher in Group E [Table 4].

Table 4.

Intragroup analysis of improvement in percentage of glottic opening score in Group L and Group E

Intragroup analysis of POGO in Group L
Variable	Sniffing, median (IQR)	After left head rotation, median (IQR)	P
POGO score	50.0 (25–75)	75 (75–100)	0.001
Intragroup analysis of POGO in Group E
Variable	Sniffing	After the epiglottis lift	P
POGO score	50 (25–75)	100 (75–100)	<0.001
Intergroup comparison of POGO score
Variable	Group L	Group E	P
1st POGO	50 (25–75)	50.0 (25–75)	0.87
2nd POGO	75 (75–100)	100 (75–100)	0.03

POGO=Percentage of glottic opening, IQR=Interquartile range

No statistically significant differences were found between the groups at any measured time point for either heart rate or MAP [Table 5]. No patient in either group had desaturation to <95%, or airway trauma. There was no failed intubation in either group, and all patients were intubated on the first attempt itself.

Table 5.

Comparison of hemodynamic variables

Time	Group L, mean±SD	Group E, mean±SD	P
Comparison of mean heart rates
Baseline	83.20±11.79	82.50±13.09	0.829
1 min after intubation	82.20±15.17	85.07±13.59	0.594
3 min after intubation	80.53±16.23	84.27±13.52	0.337
5 min after intubation	103.57±129.73	84.90±13.65	0.359
10 min after intubation	82.10±19.26	86.83±21.13	0.386
Comparison of mean arterial pressures
Baseline	94.13±19.79	99.03±18.17	0.225
1 min after intubation	90.97±19.26	93.80±19.40	0.573
3 min after intubation	84.77±15.38	89.77±15.59	0.216
5 min after intubation	87.90±14.85	82.87±15.39	0.230
10 min after intubation	86.80±13.28	83.17±11.42	0.261

SD=Standard deviation

DISCUSSION

Our findings indicate that while both LeHeR and direct epiglottis lifting techniques were successful in achieving intubation, the epiglottis lifting maneuver (Group E) resulted in a significantly superior improvement in glottic visualization, as evidenced by a higher second POGO score and a greater percentage of patients experiencing an improvement in their glottic opening compared with LeHeR position (96.7% vs. 63.3%).

LeHeR maneuver works by shifting the tongue and soft tissues to the left due to gravity and increasing the cross-sectional area of the upper airway. This causes lateral displacement of the esophagus, thus potentially enhancing both glottic visualization and airway patency.[10,11] Clinical studies and case reports show that LeHeR can significantly improve the Cormack–Lehane grade from poor to favorable views during direct laryngoscopy,[10,11,13] as well as improves POGO scores from 25% to 75% in patients with difficult airways while using C-MAC videolaryngoscope D blade.[14,15]

Direct epiglottis lifting involves placing the tip of the laryngoscope blade, typically a straight (Miller) blade or a curved blade, directly beneath the epiglottis and lifting it up to elevate the epiglottis and expose the glottis.[12,16,17] This technique offers an unobstructed view of the vocal cords in patients with a large, floppy, or posteriorly positioned epiglottis, as well as in situations where indirect lifting does not provide adequate visualization.[12,16] Direct lifting is especially valuable in difficult airways, during video laryngoscopy, and when the glottis cannot be adequately visualized using standard methods.[12,16,18]

Indirect epiglottis lifting uses a curved (Macintosh) blade placed in the vallecula, so that upward lifting transmits force via the hyoepiglottic ligament to elevate the epiglottis indirectly.[16,17,19] This method does not contact the epiglottis itself and is the standard approach for routine adult laryngoscopy, and provides sufficient exposure in normal airway anatomy.[16,17] Indirect lifting may be of limited use in difficult airway cases with anatomical variations or where the epiglottis is floppy. In such situations, conversion to the direct technique is recommended.[12,16,18]

Oh et al.[16] compared direct versus indirect epiglottis lifting using video laryngoscopy within the same patient and concluded that direct lifting resulted in significantly better glottic exposure as measured with the POGO score. Wünsch et al. showed that direct epiglottis lifting improved POGO by ~ 50%, a result noninferior to conversion to hyperangulated videolaryngoscopy while using Macintosh videolaryngoscopy, and suggested that combining direct epiglottis lifting with hyperangulated blades yielded the greatest improvement.[12]

Direct epiglottis lifting technique has been shown to shorten the time required for intubation compared to intubation without this maneuver (22–24 vs. 31 s). This technique can be taught easily as a straightforward adjunct in managing difficult airways. An intubation success rate of 100% was shown with the epiglottis lifting technique, compared to lower rates without this technique.[20] Moreover, the effectiveness of direct epiglottis lifting does not depend as much on the operator’s specific familiarity than with the different alternative head positions described. LeHeR technique may yield better results with familiarity and knowledge about the maneuver. Intubation with the head rotated to one side may pose difficulty for those who are not used to the LeHeR technique.

A significant limitation of our study is the relatively small sample size of 30 patients in each group, which may limit the generalizability of our findings. Furthermore, this was a single-center study, and the results may not be reproducible in different clinical settings with varying levels of operator experience. Future multicenter studies with larger cohorts are warranted to validate these findings. Despite these limitations, our study provides valuable evidence that the direct epiglottis lifting technique is a simple and effective maneuver for enhancing glottic visualization during C-MAC videolaryngoscopy. Therefore, we recommend incorporating a deliberate epiglottic lift into the C-MAC technique to optimize laryngeal visualization in patients with anticipated difficult airways during intubation.

CONCLUSION

In adult patients with a difficult airway, the direct epiglottis-lifting technique yielded a significantly greater improvement in glottic exposure as reflected by the proportion of patients achieving a higher POGO score (96.7% vs. 63.3%) and improved POGO score during intubation with C-MAC videolaryngoscope as compared with the left-head rotation technique. The two maneuvers were comparable with respect to intubation time, perceived ease of intubation, and hemodynamic responses.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.