European Journal of Cardiovascular Medicine

Effective airway management during general anaesthesia is a critical aspect of perioperative care, with endotracheal intubation considered the gold standard for securing the airway and preventing aspiration and hypoxia [1]. The success of intubation significantly depends on the quality of glottic visualisation during laryngoscopy. Traditional direct laryngoscopy relies on alignment of the oral, pharyngeal, and laryngeal axes to achieve a clear view of the vocal cords—a manoeuvre that can be challenging in certain populations, leading to increased intubation attempts, airway trauma, and morbidity [2].

Videolaryngoscopy (VL) has emerged as a significant advancement in airway management, enabling enhanced indirect visualisation of the glottis with reduced need for perfect anatomical alignment. Use of videolaryngoscopes has been associated with better glottic views, higher first-pass success rates, and reduced complications compared with direct laryngoscopy, particularly in difficult airway scenarios [3]. The McGrath videolaryngoscope, with its Macintosh-style blade and video capacity, represents one such device that combines ease of use with the benefits of indirect visualisation, facilitating improved intubation conditions even in patients with suboptimal airway anatomy.

External airway manipulation techniques, such as backwards-upward-rightward pressure (BURP) and jaw thrust, are commonly applied to further improve glottic visualisation during laryngoscopy. BURP, first described as a targeted manoeuvre to displace laryngeal structures to optimise view, has been shown in some studies to improve glottic exposure, although its effectiveness may vary with different devices and patient characteristics [4]. The jaw thrust manoeuvre improves airway patency by anterior displacement of the mandible and lifting of the tongue base, which can improve visualisation and facilitate intubation [5], and is often recommended as a first-line adjunct during videolaryngoscopy [6].

Comparative studies evaluating the effectiveness of BURP versus jaw thrust manoeuvres have shown mixed results. A recent randomised study using a C-MAC videolaryngoscope demonstrated that both BURP and jaw thrust improved glottic visualisation compared with the conventional technique, with jaw thrust resulting in shorter intubation times and higher ease of intubation scores [7]. Other investigations comparing modified jaw thrust with BURP techniques found that modified jaw thrust provided superior glottic views and shorter intubation times in operative airway systems other than McGrath [4]. Despite these findings, overall evidence remains somewhat heterogeneous, and direct comparisons specifically using the McGrath videolaryngoscope are limited.

Given the wide adoption of videolaryngoscopy in elective and difficult airway management, there is a need for focused evaluation of how external manoeuvres like jaw thrust and BURP influence glottic visualisation and intubation performance with individual videolaryngoscopes such as McGrath. This study, therefore, aims to compare these two manoeuvres with the conventional technique during McGrath videolaryngoscopy in adult patients undergoing elective surgery under general anaesthesia.

Effective airway management during general anaesthesia is a critical aspect of perioperative care, with endotracheal intubation considered the gold standard for securing the airway and preventing aspiration and hypoxia [1]. The success of intubation significantly depends on the quality of glottic visualisation during laryngoscopy. Traditional direct laryngoscopy relies on alignment of the oral, pharyngeal, and laryngeal axes to achieve a clear view of the vocal cords—a manoeuvre that can be challenging in certain populations, leading to increased intubation attempts, airway trauma, and morbidity [2].

Videolaryngoscopy (VL) has emerged as a significant advancement in airway management, enabling enhanced indirect visualisation of the glottis with reduced need for perfect anatomical alignment. Use of videolaryngoscopes has been associated with better glottic views, higher first-pass success rates, and reduced complications compared with direct laryngoscopy, particularly in difficult airway scenarios [3]. The McGrath videolaryngoscope, with its Macintosh-style blade and video capacity, represents one such device that combines ease of use with the benefits of indirect visualisation, facilitating improved intubation conditions even in patients with suboptimal airway anatomy.

External airway manipulation techniques, such as backwards-upward-rightward pressure (BURP) and jaw thrust, are commonly applied to further improve glottic visualisation during laryngoscopy. BURP, first described as a targeted manoeuvre to displace laryngeal structures to optimise view, has been shown in some studies to improve glottic exposure, although its effectiveness may vary with different devices and patient characteristics [4]. The jaw thrust manoeuvre improves airway patency by anterior displacement of the mandible and lifting of the tongue base, which can improve visualisation and facilitate intubation [5], and is often recommended as a first-line adjunct during videolaryngoscopy [6].

Comparative studies evaluating the effectiveness of BURP versus jaw thrust manoeuvres have shown mixed results. A recent randomised study using a C-MAC videolaryngoscope demonstrated that both BURP and jaw thrust improved glottic visualisation compared with the conventional technique, with jaw thrust resulting in shorter intubation times and higher ease of intubation scores [7]. Other investigations comparing modified jaw thrust with BURP techniques found that modified jaw thrust provided superior glottic views and shorter intubation times in operative airway systems other than McGrath [4]. Despite these findings, overall evidence remains somewhat heterogeneous, and direct comparisons specifically using the McGrath videolaryngoscope are limited.

Given the wide adoption of videolaryngoscopy in elective and difficult airway management, there is a need for focused evaluation of how external manoeuvres like jaw thrust and BURP influence glottic visualisation and intubation performance with individual videolaryngoscopes such as McGrath. This study, therefore, aims to compare these two manoeuvres with the conventional technique during McGrath videolaryngoscopy in adult patients undergoing elective surgery under general anaesthesia.

Demographic Characteristics:

A total of 135 participants were included in the study, with 45 participants in each group. The mean age was comparable across Group C (35.62 ± 13.04 years), Group J (33.69 ± 10.38 years), and Group B (35.16 ± 12.62 years), with an overall mean age of 34.82 ± 12.01 years, showing no statistically significant difference among the groups (p = 0.885). The median age and age range were also similar across the groups. Females constituted 57.78% of Group C, 51.11% of Group J, and 46.67% of Group B, while males accounted for 42.22%, 48.89%, and 53.33%, respectively. Overall, females represented 51.85% and males 48.15% of the study population. The sex distribution was comparable among the three groups, with no significant difference observed (p = 0.569), indicating that the groups were demographically comparable at baseline (Table 1).

Table 1: Demographic characteristics of the study population

Anthropometric Parameters:

The mean body weight was comparable across Group C (59.00 ± 10.24 kg), Group J (58.80 ± 9.90 kg), and Group B (61.04 ± 9.90 kg), with an overall mean weight of 59.61 ± 9.99 kg. No statistically significant difference in weight was observed among the groups (p = 0.780). Median weight and weight range were also similar across all groups. The mean height was 155.87 ± 4.20 cm in Group C, 157.13 ± 4.10 cm in Group J, and 157.73 ± 4.84 cm in Group B, with an overall mean height of 156.91 ± 4.43 cm. The difference in height among the groups was not statistically significant (p = 0.178). Median height and height range showed comparable distribution across the study groups, indicating uniform anthropometric characteristics at baseline (Table 2).

Table 2. Comparison of weight and height

The distribution of body mass index (BMI) was comparable across the three groups. Participants with BMI <18.5 kg/m² constituted 6.67% of Group C, 8.89% of Group J, and 4.44% of Group B, accounting for 6.67% of the total study population. The majority of participants were in the normal BMI category (18.5–24.99 kg/m²), comprising 48.89% in Group C, 53.33% in Group J, and 48.89% in Group B, with an overall proportion of 50.37%. Participants in the overweight category (25–29.99 kg/m²) represented 44.44% of Group C, 37.78% of Group J, and 46.67% of Group B, accounting for 42.96% of the total population.

The mean BMI was similar across the groups, being 24.25 ± 3.29 kg/m² in Group C, 23.58 ± 3.33 kg/m² in Group J, and 24.33 ± 2.79 kg/m² in Group B, with an overall mean BMI of 24.05 ± 3.14 kg/m², indicating comparable BMI distribution among the study groups (Table 3 and Figure 1).

Table 3. Body mass index (BMI) distribution

Figure 1: Comparison of mean body mass index (BMI, kg/m²) among study groups.

Glottic Visualisation:

Glottic visualisation parameters, including Modified Cormack–Lehane grade and Percentage of Glottic Opening score, were analysed using a within-subject repeated-measures framework, as each patient underwent assessment under all three manoeuvres. The Friedman test demonstrated a statistically significant overall difference in glottic visualisation across the conventional technique, jaw thrust manoeuvre, and BURP manoeuvre (p < 0.0001). Both jaw thrust and BURP manoeuvres were associated with improved glottic views compared with the conventional technique. No statistically significant difference was observed between jaw thrust and BURP manoeuvres on post-hoc analysis after adjustment for multiple comparisons (Tables 4, 5 and Figure 2). All reported percentages for glottic visualisation outcomes are based on the total number of patients (n = 135) assessed under each manoeuvre.

Table 4. Modified Cormack–Lehane (MCL) grade distribution with different airway manoeuvres (within-subject analysis, n = 135)

Table 5. Percentage of Glottic Opening (POGO) score distribution

Figure 2: Distribution of Percentage of Glottic Opening (POGO) scores among study groups.

Intubation Characteristics:

The mean laryngoscopy time was 17.16 ± 4.01 seconds in Group C, 16.07 ± 4.46 seconds in Group J, and 15.96 ± 3.83 seconds in Group B. Median laryngoscopy time and range were comparable across the three groups. Statistical analysis showed no significant difference in laryngoscopy time among the groups (p = 0.289) (Table 6 and Figure 3).

The mean intubation time was 24.36 ± 3.73 seconds in Group C, 13.49 ± 1.63 seconds in Group J, and 12.22 ± 1.24 seconds in Group B. Median intubation time and range showed a similar pattern across the groups. Statistical analysis demonstrated a significant difference in intubation time among the three groups (p < 0.0001). Pairwise comparison revealed significant differences between Group C and Group J (p < 0.0001), Group C and Group B (p < 0.0001), and between Group J and Group B (p = 0.014) (Table 7 and Figure 4).

Table 6. Laryngoscopy time (seconds)

Figure 3: Comparison of mean laryngoscopy time (seconds) among study groups.

Table 7. Intubation time (seconds)

Figure 4: Comparison of mean intubation time (seconds) among study groups.

Ease of Intubation:

Ease of insertion was graded as easy in 86.67% of Group C, while all participants in Group J and Group B (100% each) had easy insertion. Slight difficulty was observed only in Group C (13.33%). The difference in ease of insertion among the groups was statistically significant (p = 0.003). Pairwise comparison showed significant differences between Group C and Group J (p = 0.026) and between Group C and Group B (p = 0.026), while no significant difference was observed between Group J and Group B (Table 8).

Table 8. Ease of insertion grade (IDS-based)

Airway Trauma:

Blood staining on the laryngoscope blade was not observed in any participant across Group C, Group J, or Group B. In all three groups, 100% of cases showed absence of blood staining, indicating no airway trauma related to laryngoscope blade use during the procedure.

Table 9. Blood staining on the laryngoscope blade

This prospective randomised study evaluated the influence of two commonly used external airway manoeuvres, jaw thrust and backwards–upward–rightward pressure (BURP), on glottic visualisation and intubation characteristics during McGrath videolaryngoscopy. The principal findings demonstrate that both manoeuvres significantly improved glottic visualisation, reflected by superior Modified Cormack–Lehane (MCL) grades and higher Percentage of Glottic Opening (POGO) scores, when compared with the conventional technique. These improvements were accompanied by reduced intubation time and improved ease of insertion, while laryngoscopy time and airway trauma remained comparable across groups. Importantly, jaw thrust and BURP were equally effective in enhancing glottic exposure.

Glottic visualisation: MCL grade and POGO score:

Although videolaryngoscopy provides indirect visualisation of the larynx and reduces dependence on alignment of airway axes, glottic exposure may still be compromised by posterior displacement of the tongue, epiglottis, or laryngeal structures. In the present study, both jaw thrust and BURP significantly improved MCL grade and POGO score compared with the conventional technique, indicating superior laryngeal exposure.

The jaw thrust manoeuvre improves glottic visualisation primarily by anterior displacement of the mandible, which lifts the tongue base away from the posterior pharyngeal wall and indirectly elevates the epiglottis, thereby increasing the retrolingual space [6]. BURP, in contrast, acts directly on the laryngeal framework by repositioning the thyroid cartilage posteriorly, cephalad, and slightly laterally, aligning the glottic opening more favourably with the visual axis of the videolaryngoscope [8]. The absence of a significant difference between jaw thrust and BURP in terms of MCL grade and POGO score suggests that both manoeuvres are equally effective in optimising the glottic view when used with the McGrath videolaryngoscope. These findings are consistent with earlier studies evaluating external airway manipulation during videolaryngoscopy. Corda et al. demonstrated significant improvement in glottic visualisation with jaw thrust during GlideScope videolaryngoscopy [9]. Similarly, Lee et al. reported improved laryngeal views with both jaw thrust and BURP using the Clarus Video System [4]. More recently, Jain et al. observed significant improvement in glottic visualisation with both manoeuvres compared with the conventional technique during C-MAC videolaryngoscopy, with no clinically meaningful difference between jaw thrust and BURP [7]. The present study extends these observations specifically to the McGrath videolaryngoscope, for which comparative data remain limited.

Intubation characteristics and ease of insertion:

While laryngoscopy time was comparable across all groups, intubation time was significantly reduced with both jaw thrust and BURP compared with the conventional technique. This distinction is clinically relevant, as laryngoscopy time reflects the duration required to obtain the best glottic view, whereas intubation time reflects the ease and efficiency of advancing the endotracheal tube through the vocal cords. Improved glottic visualisation with jaw thrust and BURP likely reduced the need for tube manipulation, redirection, or optimisation manoeuvres, thereby shortening intubation time.

Ease of insertion, assessed using an Intubation Difficulty Scale–based grading, was also significantly better with both manoeuvres. Improved ease of insertion is a critical determinant of first-pass success, which has been shown to reduce airway-related complications and adverse events during anaesthesia [10]. Although a small difference in intubation time was observed between jaw thrust and BURP, the magnitude of this difference is unlikely to be clinically significant and may reflect subtle variations in laryngeal stabilisation during tube advancement rather than a true superiority of one manoeuvre over the other.

Previous studies have reported heterogeneous findings regarding intubation time. Jain et al. observed marginally shorter intubation times with jaw thrust compared with BURP during videolaryngoscopy [7], whereas other studies have reported comparable intubation performance between the two manoeuvres [4]. Differences in videolaryngoscope design, blade curvature, camera position, and operator familiarity may account for these variations across studies.

Laryngoscopy time and airway trauma:

The lack of a significant difference in laryngoscopy time among the three groups suggests that the application of jaw thrust or BURP does not prolong the process of obtaining an optimal glottic view. This finding aligns with earlier reports indicating that external airway manoeuvres primarily enhance view quality rather than increase procedural complexity [9].

Airway trauma, assessed by the presence of blood staining on the laryngoscope blade, was absent in all groups. Videolaryngoscopy is associated with reduced force on upper airway structures compared with direct laryngoscopy, and the addition of gentle external manoeuvres does not appear to increase mucosal injury when applied appropriately. This supports the safety of both jaw thrust and BURP as adjuncts during videolaryngoscopic intubation in patients with anticipated normal airways [11,12].

Clinical relevance:

Improved glottic visualisation, reduced intubation time, and enhanced ease of insertion have important clinical implications. Shorter intubation time may reduce the risk of hypoxaemia, particularly in patients with limited oxygen reserve, while improved ease of insertion can enhance first-pass success and overall airway safety. Given their simplicity, minimal risk, and effectiveness, both jaw thrust and BURP can be readily incorporated into routine videolaryngoscopic practice to optimise intubation conditions.

Limitations of the study:

This study was conducted at a single tertiary care centre, which may limit the generalisability of the findings to other clinical settings. Only adult patients with anticipated normal airways undergoing elective surgery were included; therefore, the results may not be applicable to patients with predicted difficult airways, emergency situations, or paediatric populations. The study was not blinded to the operator performing laryngoscopy, which could have introduced observer bias, although assessment of glottic visualisation was performed by a blinded anaesthesiologist using recorded images. Additionally, all intubations were performed by experienced anaesthesiologists, and the findings may differ with operators of varying levels of expertise.

Both jaw thrust and BURP manoeuvres significantly improve glottic visualisation during McGrath videolaryngoscopy when compared with the conventional technique. These manoeuvres also result in improved intubation characteristics, particularly reduced intubation time and greater ease of insertion, without causing haemodynamic instability or airway trauma. Jaw thrust and BURP manoeuvres were found to demonstrate comparable clinical effectiveness in enhancing glottic visualisation and intubation performance. Incorporation of these simple external airway manoeuvres during videolaryngoscopic intubation may improve intubation efficiency and safety in adult patients undergoing elective surgery.

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