European Journal of Cardiovascular Medicine

Optimal head and neck positioning for intubation has been a topic of ongoing discussion in airway management, with evolving theories over the years. Initially, full head and neck extension on a flat surface was recommended. This approach was later refined to include head elevation, commonly known as the sniffing position, by placing a pillow under the occiput. The Sniffing Position [1] is widely recognized as the standard technique, characterized by approximately 35° of neck flexion and 15° of atlanto-occipital joint extension [2]. The three-axis alignment theory (TAAT) [3] provides the most accepted anatomical explanation for this positioning. Neck flexion in the Sniffing Position is achieved by elevating the head, typically using pillows or a head ring.

An alternative is the Modified Ramped Position, in which the bed is partially inclined at approximately 25°, with the head elevated so that the face remains parallel to the ceiling. The neck and torso are positioned at a 25° angle, while the legs remain parallel to the ceiling. To align the external auditory meatus with the sternal notch, pillows or towels may be adjusted. Once the desired positioning is achieved, the bed height is modified to optimize the patient’s mouth level for intubation [4].

Several studies indicate that head elevation enhances glottic visualization; however, there is no consensus on the exact elevation required [5]. A commonly used marker for optimal positioning is the horizontal alignment of the external auditory meatus with the sternal notch, a principle also applied in ramping, particularly for obese patients. The goal of these adjustments is to achieve optimal alignment of the oral, pharyngeal, and laryngeal axes, thereby facilitating intubation.

A key factor contributing to difficult intubation is poor glottic visualization during laryngoscopy. Enhancing the laryngoscopic view increases the likelihood of successful intubation, reduces the number of attempts required, and minimizes the need for alternative airway management techniques. Proper pre-induction positioning is therefore critical for intubation success [6]. Several studies highlight the impact of head and neck positioning in improving intubation outcomes, reducing tracheal trauma, and minimizing post-intubation complications.

This study aims to evaluate whether a custom pillow designed to achieve horizontal alignment of the external auditory meatus with the sternal notch leads to better glottic visualization and facilitates intubation compared to a fixed-height pillow. There is currently limited research in this area, and this study seeks to provide valuable insights into this aspect of airway management.

Research Question

Can we improve intubating conditions by Modified Ramped Position?

Objective

To compare the Glottic view using Cormack Lehane grading in Sniffing Position (by Fixed Pillow) and Modified Ramped Position (by Customized Pillow) and to compare the number of attempts taken for endotracheal intubation in both groups.

Study Design

A cross-sectional study was conducted to evaluate the effect of head and neck positioning on ease of intubation.

Study Setting

The study was carried out in the Department of Anaesthesiology at Government Medical College, Idukki, a tertiary care center in a rural setting.

Study Period

The study was conducted over a period of six months from the date of clearance from the Institutional Ethics Committee (IEC).

Study Participants

The study included two groups: Group A, in which patients were intubated in the sniffing position, and Group B, in which patients were intubated in the Modified Ramped Position. Patients classified under ASA (American Society of Anesthesiologists) classes 1, 2, and 3, aged above 18 years, undergoing elective surgery under general anesthesia, and who provided informed consent were included.

Exclusion Criteria

Patients who were pregnant, had a BMI greater than 35, had an unstable cervical spine, or had contraindications to conventional laryngoscopy or any drugs used in the study were excluded.

Sample Size Calculation

The sample size was calculated using the formula:

Sample size is calculated by using the formula

[Z (1-α/2) + Z (1-β) ] 2 = 7.9

According to a study conducted by Sarah Lotfi and et al

P 1 = 44.6

P 2 = 16

Q 1 = 55.4

Q 2 = 84

By using above values, sample size is 36 in each group.

Method of Data Collection

Institutional Ethical Committee and Institutional Research Committee approval were obtained before initiating the study. Informed written consent was obtained from all participants.

Preoperative evaluation was conducted in the Pre-Anesthesia Clinic. Standard monitoring devices, including electrocardiogram, pulse oximetry (SpO₂), and non-invasive blood pressure, were applied, and an intravenous cannula was placed. Patients were positioned either in the Sniffing Position (Group A) using a standard 4 cm head ring or in the Modified Ramped Position (Group B) using a Customized Pillow to achieve horizontal alignment of the external auditory meatus with the sternal notch.

Preoxygenation was performed with 100% oxygen for three minutes using a close-fitting mask. Standard intravenous induction was carried out using fentanyl (2 µg/kg), propofol (2 mg/kg), and succinylcholine (1.5 mg/kg) for muscle relaxation. After 60 seconds of ventilation, direct laryngoscopy and endotracheal intubation were performed by a senior anesthesiologist.

The Cormack-Lehane grade observed during laryngoscopy, the number of intubation attempts, and the use of additional airway assistance (such as a bougie, stylet, or external laryngeal manipulation) were recorded.

Study Variables

• Independent Variables: Age, sex, weight, height, and modified Mallampati classification.
• Outcome Variables: Cormack-Lehane grade, number of intubation attempts, and the need for pillow adjustment to facilitate successful intubation.

Outcome Measurement

The primary outcome was the comparison of Cormack-Lehane grades between the two groups. Secondary outcomes included the number of intubation attempts and the need for additional airway assistance.

Tool and Technique

A structured proforma was used to collect data systematically.

Data Analysis

Data were entered into MS Excel and analyzed using SPSS software. Quantitative variables were expressed as mean and standard deviation, while categorical variables were expressed as proportions. Chi-square test was used to analyze categorical variables. A p-value of less than 0.05 was considered statistically significant. All analyses used SPSS (Statistical Package for the Social Sciences) software version 26.

Ethical Considerations

The study was conducted only after obtaining clearance from the Institutional Ethics Committee (IEC). Informed consent was obtained from all participants, ensuring confidentiality and adherence to ethical guidelines.

Budget Involved

No additional budget was required for the study.

Expected Outcome

It was anticipated that intubation in the Modified Ramped Position would result in improved glottic visualization and ease of intubation compared to the sniffing position.

Demographic Characteristics

The study included a total of 72 participants, with a mean age of 41.08 ± 13.00 years (range: 17–62 years). Females comprised 55.6% (n=40) of the study population, while males accounted for 44.4% (n=32). Regarding BMI distribution, 52.8% (n=38) had normal weight, 31.9% (n=23) were overweight, 6.9% (n=5) were obese, and 8.3% (n=6) were underweight. The majority of participants belonged to ASA Class 1 (73.6%), followed by ASA Class 2 (25.0%) and ASA Class 3 (1.4%). Participants were evenly distributed between Group A (sniffing position) and Group B (Customized Pillow position), each comprising 50% (n=36) of the study population.

Table 1: Demographic Characteristics

Mean ± SD of Continuous Variables

The mean BMI was 24.20 ± 4.00 kg/m², ranging from 17.28 to 36.16 kg/m². This indicates that the study population included individuals across different BMI categories, from underweight to obese.

Table 2: Mean ± SD of Continuous Variables

3. Cormack-Lehane (CL) grades between Group A (FP) and Group B (CP).

The Cormack-Lehane (CL) grade distribution between Group A (Fixed Pillow - FP) and Group B (Customised Pillow - CP) showed a statistically significant difference (p = 0.012). In CL Grade 1, which represents the best visualisation, 20 cases (45.5%) were in Group A (FP) and 24 cases (54.5%) were in Group B (CP), indicating a better airway view in the CP group. For CL Grade 2A, 1 case (12.5%) was in Group A (FP) and 7 cases (87.5%) were in Group B (CP), again suggesting superior visualisation in the CP group. In CL Grade 2B, representing poor visualisation, 12 cases (80%) were in Group A (FP), while only 3 cases (20%) were in Group B (CP). Finally, in CL Grade 3, indicating the most difficult intubations, 3 cases (60%) were in Group A (FP) and 2 cases (40%) were in Group B (CP). Overall, the Customised Pillow (CP) group demonstrated significantly better airway visualisation, as indicated by higher proportions of Grade 1 and 2A, making it the preferred choice for easier intubation.

5. Use of assistance tools (Bougie, BURP, Bougie + BURP, Not used) between the two groups.

The use of assistance tools also differed significantly between the groups (p = 0.032). Bougie was required in 1 case (20.0%) in FP and 4 cases (80.0%) in CP, while Bougie + BURP was needed in 5 cases (100.0%) in FP and none (0.0%) in CP. The use of BURP alone was required in 3 cases (75.0%) in FP and 1 case (25.0%) in CP. Importantly, the number of cases where no assistance was needed (Nil) was significantly higher in CP (31 cases, 53.4%) compared to FP (27 cases, 46.6%), reflecting easier intubation in the CP group. These findings suggest that the Customised Pillow (CP) group required less airway support, demonstrating its advantage in optimizing head and neck positioning.

Endotracheal intubation is a fundamental procedure in airway management, with the patient’s head and neck position playing a crucial role in optimizing glottic visualization and ease of intubation. Traditionally, the Sniffing Position (SP) has been considered the gold standard for improving laryngeal exposure. However, recent studies have explored the Modified Ramped Position (MRP) as a potentially superior alternative, particularly in patients with obesity and other difficult airway conditions. The present study aimed to compare glottic visualization using Cormack-Lehane (CL) grading and the number of intubation attempts required in the Sniffing Position versus a Customized Pillow position (a form of MRP).

Demographic Comparisons

Our study included 72 participants with a mean age of 41.08 ± 13.00 years (range: 17–62 years), with a gender distribution of 55.6% females and 44.4% males. The majority of participants had a normal BMI (52.8%), with 31.9% classified as overweight, 6.9% as obese, and 8.3% as underweight. The distribution of ASA classification was predominantly Class 1 (73.6%), followed by Class 2 (25.0%) and Class 3 (1.4%).

The demographic characteristics in our study align closely with those reported by Sindhuja et al. (2024), who conducted a similar study on 160 participants. Their findings emphasized that mask ventilation was easier in the MRP group (79.6%) compared to the SP group (63.4%, p = 0.023), reinforcing the hypothesis that airway management is facilitated by an elevated head position.

Glottic Visualization Using Cormack-Lehane Grading

A significant finding in our study was the improved glottic visualization in the Customized Pillow position compared to the sniffing position. CL Grade 1 (best visualization) was observed in 54.5% of cases in the Customized Pillow group, compared to 45.5% in the sniffing position. Similarly, for CL Grade 2A, 87.5% of cases were in the Customized Pillow position, whereas only 12.5% were in the sniffing position. The more difficult grades, CL 2B and CL 3, were predominantly seen in the Sniffing Position (80% and 60%, respectively), compared to lower rates in the Customized Pillow position (20% and 40%, respectively).

Jung et al. (2022) conducted a randomized crossover study among emergency medicine students and reported similar findings, noting that the Modified Ramped Position provided better glottic visualization and improved the ease of intubation. Likewise, Lotfi et al. (2023) demonstrated that the modified RAMP roll significantly reduced intubation difficulty and procedure duration (p = 0.019). These results corroborate our findings that the Customized Pillow position enhances glottic exposure, reducing the likelihood of requiring multiple intubation attempts.

Conversely, Alimian et al. (2021) found no significant differences in laryngoscopy grade, ventilation score, or number of intubation attempts between RAMP and a modified RAMP position in morbidly obese patients. This discrepancy suggests that while MRP may be beneficial in non-morbidly obese individuals, its effectiveness in morbidly obese populations may be limited.

Use of Airway Assistance Tools

The requirement for airway assistance tools also differed significantly between groups (p = 0.032). Bougie was used in 20% of cases in the Sniffing Position group but was required in 80% of cases in the Customized Pillow group. Interestingly, the Bougie + BURP maneuver was exclusively needed in the Sniffing Position group (100%), while none in the Customized Pillow group required it. Additionally, a significantly higher proportion of cases required no assistance in the Customized Pillow position (53.4%) compared to the Sniffing Position (46.6%), further supporting the improved ease of intubation in the MRP group.

These findings align with Sindhuja et al. (2024), who reported a lower incidence of high Intubation Difficulty Scale (IDS) scores (>5) in the MRP group (3.2%) compared to the Sniffing Position group (4.3%). However, Semler et al. (2017) found contrasting results, reporting that the ramped position increased the incidence of difficult intubation (12.3% vs. 4.6%, p = 0.04) and decreased the first-attempt success rate (76.2% vs. 85.4%, p = 0.02). It is important to note that their study focused on critically ill adults, which may account for the increased difficulty in intubation.

Clinical Implications and Study Limitations

The findings from our study suggest that the Modified Ramped Position, particularly using a Customized Pillow, may offer superior glottic visualization and easier intubation compared to the traditional sniffing position. This could be particularly beneficial for patients with higher BMIs and those with potentially difficult airways. However, discrepancies in the literature suggest that patient characteristics, including morbid obesity and critical illness, may influence the efficacy of these positioning strategies.

One limitation of our study is the relatively small sample size (n=72), which may limit generalizability. Additionally, patient-specific anatomical variations were not extensively analyzed, which may have influenced intubation difficulty. Further research with larger cohorts and stratification based on BMI and comorbidities would be valuable in refining airway management protocols.

In conclusion, our study supports the use of a Modified Ramped Position (Customized Pillow) as an effective alternative to the Sniffing Position for endotracheal intubation. This position was associated with improved glottic visualization, reduced CL grades, and a decreased need for airway assistance tools. These findings are consistent with those reported by Jung et al. (2022), Lotfi et al. (2023), and Sindhuja et al. (2024). However, conflicting results from Semler et al. (2017) highlight the importance of considering patient population and clinical context when selecting intubation positioning strategies. Future studies should focus on validating these findings in larger and more diverse populations, particularly among critically ill and morbidly obese patients, to further refine best practices in airway management.

Conflict of interest: Nil

1. Magill Iw. Endotracheal Anesthesia. The American Journal Of Surgery 1936;34(3):450–5.
2. Horton Wa, Fahy L, Charters P. Defining A Standard Intubating Position Using “Angle Finder.” British Journal Of Anaesthesia 1989;62(1):6–12.
3. Bannister F. Direct Laryngoscopy And Tracheal Intubation. The Lancet 1944;244(6325):651–4.
4. Lebowitz PW, Shay H, Straker T, Rubin D, Bodner S. Shoulder and head elevation improves laryngoscopic view for tracheal intubation in nonobese as well as obese individuals. Journal of Clinical Anesthesia 2012;24(2):104–8.
5. Sullivan CB, Peterson J, Hoffman H. Optimal positioning to image the subglottis during transnasal flexible laryngoscopy
6. Lotfi S, Mohamadi MS, Ahmadi A, Rezvani S, Sehat M, Tabaraii R. Success rates of endotracheal intubation using the standard method versus the modified-ramped position. Ann Med Surg (Lond). 2023 Sep 27;85(11):5491-5496. doi: 10.1097/MS9.0000000000001331. PMID: 37915676; PMCID: PMC10617870.
7. Semler MW, Janz DR, Russell DW, Casey JD, Lentz RJ, Zouk AN, deBoisblanc BP, Santanilla JI, Khan YA, Joffe AM, Stigler WS, Rice TW; Check-UP Investigators(∗); Pragmatic Critical Care Research Group. A Multicenter, Randomized Trial of Ramped Position vs Sniffing Position During Endotracheal Intubation of Critically Ill Adults. Chest. 2017 Oct;152(4):712-722. doi: 10.1016/j.chest.2017.03.061. Epub 2017 May 6. PMID: 28487139; PMCID: PMC5812765.
8. Alimian M, Zaman B, Seyed Siamdoust SA, Nikoubakht N, Rounasi R. Comparison of RAMP and New Modified RAMP Positioning in Laryngoscopic View During Intubation in Patients with Morbid Obesity: A Randomized Clinical Trial. Anesth Pain Med. 2021 Jun 29;11(3):e114508. doi: 10.5812/aapm.114508. PMID: 34540638; PMCID: PMC8438731.
9. Lotfi, Sarah MDa; Mohamadi, Mohamad sepehr MDb; Ahmadi, Abbas MDb; Rezvani, Sourena MDb; Sehat, Malihe MDb; Tabaraii, Reihane MDb. Success rates of endotracheal intubation using the standard method versus the modified-ramped position. Annals of Medicine & Surgery 85(11):p 5491-5496, November 2023. | DOI: 10.1097/MS9.0000000000001331
10. Sindhuja, Anala; Bangera, Ananda. Modified Ramped Position: Is It the New Hope to Overcome Unanticipated Difficult Airway? A Comparative Study. Journal of Datta Meghe Institute of Medical Sciences University 19(4):p 677-685, Oct–Dec 2024. | DOI: 10.4103/jdmimsu.jdmimsu_246_24
11. Jung S, Jung JH, Yun SW. Efficiency of Modified Ramped Position during the endotracheal intubation. InProceedings of the Korean Institute of Information and Commucation Sciences Conference 2022 (pp. 306-308). The Korea Institute of Information and Commucation Engineering.