European Journal of Cardiovascular Medicine

The airway comprises the nasal and oral cavities, pharynx, larynx, trachea, and major bronchi, serving as the channel for air to enter and exit the lungs. Maintaining a patent airway is essential for effective ventilation, and any compromise can be fatal.^[1] The gold standard for airway management is endotracheal intubation, commonly performed during general anaesthesia, unconsciousness, or respiratory failure.

Successful intubation primarily depends on the visualisation of the glottis during direct laryngoscopy. The Cormack-Lehane grading system,^[2] later modified by Yentis and Lee, assesses glottic visibility from complete (grade 1) to none (grade 4). Poor glottic view is associated with difficult intubation and can be worsened by factors like obesity, anatomical variations, and limited mouth opening.^[3] External laryngeal manipulation is often used to improve the glottic view in such cases.^[4]

Common external techniques include the BURP (Backward, Upward, Rightward Pressure) manoeuvre, jaw thrust, and cricoid pressure.^[5] Knill introduced the BURP technique in 1993 to enhance glottis visualisation during intubation,^[6] which showed significant improvements in some adult patient studies.^[7] The jaw thrust, described by F. von Esmarch in 1877,^[8] improves airway patency by anteriorly displacing the mandible, lifting the tongue, and preventing laryngeal collapse.^[9] Sellick’s cricoid pressure, introduced in 1961 to prevent regurgitation, has a debated role in improving glottic view.^[10] Studies have shown that combining BURP with cricoid pressure can sometimes worsen visualisation.^[11]

Despite their widespread use, the choice of technique often depends on clinician preference and institutional guidelines due to limited comparative data. Hence, this study aims to evaluate and compare the effectiveness of different laryngeal manipulation techniques in improving glottic visualisation during conventional laryngoscopy.

Aims and Objectives

This study aimed to evaluate and compare the effectiveness of various external laryngeal manoeuvres in improving the glottic view and facilitating successful intubation during video laryngoscopy. Specifically, the study seeks to compare the laryngoscopic view achieved using the conventional technique with that obtained through external laryngeal manipulations, including anterior manipulation of the cricoid cartilage, anterior mandibular displacement (jaw thrust), and the BURP manoeuvre. Additionally, the study aims to assess and compare the time required for successful intubation using each of these techniques to determine their relative efficiency and effectiveness during video laryngoscopy.

Study Design

This comparative study was conducted in the Department of Anaesthesiology and Critical Care, ACSR Medical College and Government General Hospital, over a period of 6 months from 07 February 2025 to 08 August 2025. The study involved 120 patients scheduled for elective surgeries requiring general anaesthesia with endotracheal intubation. Patients meeting the specified inclusion criteria were enrolled to evaluate and compare the effectiveness of different external laryngeal manoeuvres-namely anterior manipulation of the cricoid cartilage, anterior mandibular displacement (jaw thrust), and the BURP manoeuvre-against the conventional laryngoscopy technique. The study aimed to assess both the laryngoscopic view and the time taken for successful intubation using each technique during video laryngoscopy.

Inclusion and Exclusion Criteria

The study included patients aged 18 to 65 years, classified as ASA grade I or II, with no comorbidities, who provided written informed consent and were scheduled for elective surgery under general anaesthesia. Patients were excluded if they had a history of head or neck trauma or scarring, oral cavity pathology, maxillofacial anomalies, restricted neck movements, limited mouth opening, or obesity (BMI >30 kg/m²).

Sample Size Calculation

n=Z²x p x q / d²

Data Collection Tools

Primary data were collected through patient history, clinical examination, and intraoperative observations during intubation. Tools used included direct observation, structured interviews, clinical protocols, and standard airway assessment tests. A structured proforma was used to record preoperative airway assessment parameters, Cormack and Lehane grading, intubation time, and any complications.

Data Collection Procedure

Each patient underwent a preoperative airway assessment including, the modified Mallampati score, thyromental and sternomental distances, inter-incisor gap, and neck extension. Following standard anaesthetic induction, video laryngoscopy was performed using the conventional technique and three external laryngeal manoeuvres (cricoid manipulation, jaw thrust, and BURP), applied in random order by a blinded assistant. The glottic view was graded using the modified Cormack and Lehane scale by the same experienced anaesthesiologist. Tracheal intubation was then carried out with the assigned manoeuvre, and intubation time was measured from scope insertion to capnographic confirmation. Vital signs and signs of oropharyngeal trauma were recorded pre- and post-intubation.

Statistical Analysis

Statistical analysis was conducted using the SPSS (Statistical Package for the Social Sciences) software. Categorical data were expressed as frequencies and percentages, while quantitative data were presented as mean, median, and maximum values. To compare the means of variables between different groups, independent ‘t’ tests and ANOVA were applied. Graphical representations were created using Microsoft Excel 2010. A p-value of less than 0.05 was considered statistically significant.

Table 1 illustrates the age distribution among the four study groups.

Table 2 observes gender distribution, showing more females in Group 1 and more males in other groups.

Table 3 presents the weight statistics, with Group 4 showing the highest average weight.

Table 4 summarizes inter-incisor gap, where most patients had >4 cm across groups.

Table 5 illustrates Mallampati grading, showing Grade II as the most common across groups.

Table 6 shows the time taken for intubation, lowest in Group 4 and highest in Group 1.

Table 7 reports the number of intubation attempts, with Group 3 showing all successful on first attempt.

The primary factor influencing subsequent tracheal intubations during direct laryngoscopy is glottis visualisation. External laryngeal manipulations are typically the first and easiest approaches to facilitate the view during the initial intubation attempt in the event of complications.^[12] The BURP manoeuvre, Sellick's manoeuvre, and jaw thrust are some of the well-known external laryngeal manipulation techniques that are widely employed to enhance glottis vision and ease of tracheal intubation.^[5]

Knill developed the BURP procedure in 1993 to enhance the glottis vision during tracheal intubation.^[6] Some authors tested the effectiveness of this procedure on adult patients. During attempts at endotracheal intubation, they showed a noticeably improved view of the glottis in that cohort.^[7] Sellick first described the cricoid pressure procedure in 1961, primarily to prevent potential regurgitation. Additionally, it was applied to enhance glottis vision.^[10] Its effectiveness in improving laryngoscopic view is debatable because some authors claim that the view got worse after this manoeuvre.^[13] Snider et al. attempted to evaluate the effects of combining the BURP procedure with cricoid pressure in the meantime, and they discovered that this combination significantly degraded the view in many instances.^[11]

The effectiveness of the BURP, jaw thrust and Sellick manoeuvres in this demographic has not been thoroughly researched. There is still a dearth of information on this subject. This observational trial's objective was to compare the laryngoscopic view and time taken for successful intubation by conventional technique and external laryngeal manoeuvres (cricoid pressure, jaw thrust and BURP manoeuvre) during video laryngoscopy.

A total of 120 patients were analysed, divided into 4 equal groups. Group 1: Standard or conventional laryngoscopy technique. Group 2: Anterior manipulation of cricoid cartilage. Group 3: Anterior mandibular displacement of jaw. Group 4: BURP manoeuvre.

Age: The average age in Group 1 was 45.37 years. Comparable age values were noted in the other groups and consistent with the mean age of the conventional group (48.7 years) in Lee AR et al.^[14] and BURP (45.1) and Jaw thrust (48.2). Corda D et al.^[15] reported a higher mean age of 66 years, while Soltani A et al.^[16] reported a mean of 4.4 years in paediatric patients.

Gender: Group 1 had more females, while Groups 2, 3, and 4 had more males. Lee AR et al.^[14] reported similar gender distributions across groups. In the study by Corda D et al.^[15] 53% were males. Soltani A et al.^[16] also reported male predominance (68.7%).

Weight: Average weights in Groups 1 to 4 ranged from 63.03 kg to 66.63 kg. These values align with Lee AR et al.^[14] who noted mean weights of 65.5 kg (conventional), 63.4 kg (BURP), and 66.9 kg (Jaw thrust). Corda D et al.^[15] reported a higher mean weight of 81 kg, while Soltani A et al.^[16] reported 15.7 kg for paediatric subjects. Wilson et al.^[17] identified obesity as a predictor of difficult intubation.

ASA: ASA grades I and II were most common across all groups, with Group 3 showing the highest proportion of Grade I (70%).

Inter-incisor gap: Most patients had a gap >4 cm. Wilson et al.^[22] defined <5 cm as predictive of difficulty. Khan et al.^[18] supported <4.5 cm as a difficult predictor. This study aligns with previous findings, suggesting a cut-off of 38 mm.

Mallampati grade: Grade II was most common (40.8%), followed by III, I, and IV. These findings are in agreement with Lee AR et al.^[14] and Corda D et al.^[15] The Mallampati test is a validated predictor of difficult airways,^[19] with scores >2 linked to increased difficulty.^[20]

Thyromental distance: Most patients had a thyromental distance of 6–6.5 cm. One patient in Group 4 had <6 cm. Mean values from Lee AR et al.^[14] and Corda D et al.^[15] ranged between 5.5 and 8.3 cm. A threshold of <6.5 cm is considered predictive of difficult intubation by Khan et al.^[18] consistent with prior findings.^[20]

Upper lip bite test: Most patients (62.5%) had Grade I. Only one had Grade IV. These values are similar to Corda D et al.^[15]

Intubation duration: Group 1 took the longest (88.23s) and Group 4 the shortest (26.53s). Lee AR et al.^[14] reported 20s (conventional), 22s (BURP), and 14s (jaw thrust).

Intubation attempts: Success on the first attempt was highest in Groups 3 and 4. Lee AR et al.^[14] reported similar findings. However, the difference was not statistically significant.

Failed intubation: Group 1 had the most failed attempts (46.7%). None occurred in Groups 3 and 4. Lee AR et al.^[14] similarly found failures primarily in conventional and BURP groups.

CL grade: Group 4 (BURP) showed the best CL grades with 91.7% Grade I. In comparison, Group 1 had the most Grade III/IV. Lee AR et al.^[14] and Cormack-Lehane's original scale^[21] support these findings. Mallampati, interincisor gap, and thyromental distance were also noted as indirect predictors.^[19]

BURP: The BURP manoeuvre significantly improved intubation conditions and reduced time. Knill et al.^[6] and Takahata et al.^[5] support its effectiveness in visualising the glottis and enabling successful intubation. Mohseni M et al.^[22] also found BURP enhanced glottic exposure.

Jaw Thrust: Jaw thrust was effective in improving laryngeal view and reducing time. It repositions the base of the tongue and epiglottis, as shown by Murashima et al.^[23] Modified jaw thrust is especially helpful in restricted airway situations and complements video-assisted techniques.^[24]

Cricoid Pressure: Originally described by Sellick, cricoid pressure prevents regurgitation.^[25] However, its impact on glottic view is debated, requiring proper technique and understanding of anatomy.

Videolaryngoscopy: Video laryngoscopy improves success rates and glottic views, as shown by Jungbauer A. et al.^[26] and supported by Chemsian RV et al.^[27] Hossfeld B et al.^[28] It is also a preferred teaching tool due to its ease of use and clarity of view.

In summary, the BURP and jaw thrust manoeuvres provide significantly improved outcomes in laryngoscopic view and intubation success. Video laryngoscopy further enhances these effects, confirming its role in modern airway management.

Limitations

This study has several limitations. It was randomized with a relatively small sample size and conducted in a tertiary care referral hospital, which limits the generalizability of findings to broader populations. All participants were Indian adults over 18, making it difficult to extrapolate results to Western populations due to anthropometric differences. Imaging modalities like ultrasound, CT, and MRI could not be used in cases of difficult intubation, limiting anatomical assessment. Key variables like neck circumference and head-neck mobility were not adequately captured, and the study relied on limited criteria to define difficult intubation without using standardized scoring systems. Additionally, operator preference and skill influenced the use of intubation devices, complicating comparative analysis of their effectiveness.

In conclusion, this study demonstrates that external laryngeal manoeuvres, particularly the BURP technique, significantly improve intubation success rates, reduce intubation time, and enhance laryngeal view during video laryngoscopy compared to the conventional method. Among the techniques studied, the BURP manoeuvre proved most effective, with all patients successfully intubated on the first attempt and the shortest average intubation time. Video laryngoscopy further enhanced visualization and coordination, reinforcing its value in managing difficult airways and improving overall intubation outcomes.

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