Bag-mask ventilation (BMV) is a fundamental airway management skill in anaesthesia and emergency medicine. It is the primary method of maintaining oxygenation and ventilation during induction of general anaesthesia, cardiopulmonary resuscitation, and unexpected difficult airway situations until a definitive airway is secured. Failure to provide effective mask ventilation can rapidly lead to hypoxaemia, hypercapnia, aspiration, cardiac arrest, and neurological injury. Effective one-hand BMV requires two key elements: a good face-mask seal and adequate jaw lift to maintain upper airway patency while delivering sufficient tidal volume with minimal air leak. Mask ventilation may be difficult in patients with obesity, facial hair, edentulous state, obstructive sleep apnoea, reduced mandibular mobility, or abnormal airway anatomy. Ventilation quality is also influenced by the operator's experience, hand size, grip strength, and mask-holding technique. The EC clamp technique is the traditional and most widely taught one-hand method. Although familiar and easy to perform, it may provide an inadequate mask seal and jaw thrust in difficult airways, leading to air leakage, lower tidal volume, operator fatigue, and gastric insufflation. The Thenar Eminence (TE) technique offers more even mask pressure and improved jaw lift but is primarily designed for two-handed ventilation, making one-handed use less ergonomic. The Hook grip is a newer one-hand technique in which the thenar eminence and thumb stabilize the mask while the remaining fingers hook beneath the mandible to provide a stronger jaw lift. This design may improve mask seal, airway patency, and ventilation while reducing operator fatigue. Early studies have reported better ventilation success and higher end-tidal carbon dioxide (EtCO₂) values with the Hook grip, but evidence remains limited, particularly in the Indian population. Therefore, this study compared the EC, Thenar Eminence, and Hook grip techniques in adult patients undergoing elective surgery under general anaesthesia. Ventilation quality was assessed using tidal volume, EtCO₂, chest rise, gastric distension, oxygen saturation, and haemodynamic parameters. We hypothesised that the Hook grip would provide superior ventilation with greater tidal volume, better EtCO₂, improved chest expansion, and less gastric distension, while maintaining haemodynamic stability. The findings may help anaesthesiologists select the most effective one-hand BMV technique for routine and emergency airway management.

Study Design and Setting This prospective comparative observational study was conducted in the Department of Anaesthesiology at a tertiary care teaching hospital after obtaining approval from the Institutional Ethics Committee (IEC Approval No:MPGI/IEC/outward No/68/2024) conducted in strict accordance with the ICMR National Ethical Guidelines for Biomedical and Health Research Involving Human Participants (2017) and the Declaration of Helsinki (2013 revision) and institutional guidelines.Written informed consent was obtained from all participants before enrolment. Study Population A total of 111 adult patients scheduled for elective surgical procedures under general anaesthesia were included in the study. Patients were allocated equally into three groups according to the one-hand bag-mask ventilation (BMV) technique used: • Group EC (n = 37): EC grip • Group TE (n = 37): Thenar Eminence grip • Group Hook (n = 37): Hook grip Inclusion Criteria Patients fulfilling all the following criteria were included: • Age 18–60 years • Either sex • American Society of Anesthesiologists (ASA) physical status I or II • Scheduled for elective surgery under general anaesthesia • Provided written informed consent Exclusion Criteria Patients were excluded if they had: • Anticipated difficult airway • Facial deformity or facial trauma • Edentulous state • Body mass index >30 kg/m² • Pregnancy • Increased risk of aspiration • Upper airway pathology • Requirement for rapid sequence induction • Refusal to participate Blinding:Single blind study. Observer blinded (data collector). Performer blinding impossible (technique-specific hand positioning). Sample Size The study included 111 patients (37 in each group). Sample size estimation was based on previous published studies(Balafar et al, Soleimanpour et al) comparing one-hand bag-mask ventilation techniques and was calculated to achieve adequate statistical power for detecting significant differences in ventilation quality. Procedure Standard fasting guidelines were followed. After arrival in the operating room, routine monitoring including electrocardiography (ECG), non-invasive blood pressure (NIBP), pulse oximetry (SpO₂), and capnography was instituted. All patients received standard anaesthetic induction according to institutional protocol. Following induction and achievement of adequate muscle relaxation, one-hand bag-mask ventilation was performed using the allocated technique by an experienced anaesthesiologist. Appropriate-sized face masks and breathing circuits were used in all patients. Ventilation was maintained with 100% oxygen using controlled manual ventilation for three minutes before tracheal intubation. Study Techniques EC Grip The thumb and index finger formed a "C" around the face mask while the middle, ring, and little fingers lifted the mandible to form an "E," thereby maintaining mask seal and airway patency. Thenar Eminence (TE) Grip The thenar eminence and thumb were used to stabilize the mask while the remaining fingers elevated the mandible to achieve jaw thrust and maintain airway patency. Hook Grip The thenar eminence and thumb rested over the mask, while the remaining fingers were hooked beneath the angle of the mandible to provide effective jaw lift and mask seal. Outcome Measures Primary Outcome The quality of one-hand bag-mask ventilation was assessed by: • Delivered tidal volume (mL) • End-tidal carbon dioxide (EtCO₂) Secondary Outcomes The following parameters were also evaluated: • Adequacy of chest rise • Gastric distension • Oxygen saturation (SpO₂) • Heart rate • Systolic blood pressure • Diastolic blood pressure All variables were recorded at 1, 2, and 3 minutes after initiation of bag-mask ventilation. Statistical Analysis Data were entered into Microsoft Excel and analysed using appropriate statistical software. Continuous variables were expressed as mean ± standard deviation (SD), whereas categorical variables were expressed as frequencies and percentages. One-way analysis of variance (ANOVA) was used for comparison of continuous variables among the three groups, followed by post-hoc analysis where appropriate. Categorical variables were compared using the Chi-square test or Fisher's exact test. A p-value <0.05 was considered statistically significant.

Table 1: Comparison of Baseline Demographic and Airway Characteristics Among Study Groups Variable EC Group (n=37) TE Group (n=37) Hook Group (n=37) P value Interpretation Age (years) 38.22 ± 15.37 42.05 ± 10.83 35.70 ± 14.62 0.140 Not significant Sex (Male/Female) 14/23 (37.8%/62.2%) 21/16 (56.8%/43.2%) 20/17 (54.1%/45.9%) 0.212 Not significant BMI (kg/m²) 21.54 ± 1.45 20.97 ± 1.24 21.41 ± 1.42 0.182 Not significant Mallampati Grade I 12 (32.4%) 11 (29.7%) 13 (35.1%) 0.999 Not significant Mallampati Grade II 18 (48.6%) 19 (51.4%) 18 (48.6%) 0.999 Not significant Mallampati Grade III 6 (16.2%) 6 (16.2%) 5 (13.5%) 0.999 Not significant Mallampati Grade IV 1 (2.7%) 1 (2.7%) 1 (2.7%) 0.999 Not significant The three study groups were comparable with respect to baseline demographic characteristics (age, sex, and BMI) and airway assessment (Mallampati classification), with no statistically significant differences observed between the groups (p > 0.05). This indicates successful baseline matching prior to intervention. Table 2: Comparison of ventilation parameters among the three groups Parameter Time EC Group (Mean ± SD) TE Group (Mean ± SD) Hook Group (Mean ± SD) P value Tidal Volume (mL) 1 min 324.70 ± 29.91 243.51 ± 43.40 343.68 ± 50.76 <0.001 2 min 316.81 ± 38.37 262.11 ± 32.34 341.95 ± 34.01 <0.001 3 min 320.81 ± 34.71 258.97 ± 39.73 352.16 ± 37.40 <0.001 EtCO₂ (mmHg) 1 min 28.68 ± 2.70 27.73 ± 3.58 28.89 ± 2.13 0.184 2 min 28.78 ± 2.41 27.54 ± 3.65 29.19 ± 2.60 0.046 3 min 29.43 ± 1.97 27.73 ± 3.72 29.84 ± 2.33 0.003 The Hook technique demonstrated significantly higher tidal volumes at all three time points (p < 0.001). Although EtCO₂ values were comparable at 1 minute (p = 0.184), the Hook group showed significantly higher EtCO₂ values at 2 and 3 minutes, indicating more effective ventilation. Table 3: Comparison of clinical indicators of ventilation Parameter Time EC Group TE Group Hook Group P value Adequate Chest Rise (%) 1 min 100.0 100.0 100.0 1.000 2 min 78.4 40.5 97.3 <0.001 3 min 91.9 48.6 97.3 <0.001 Gastric Distension Present (%) 1 min 27.0 70.3 2.7 <0.001 All three techniques achieved adequate chest rise during the first minute of ventilation. However, from the second minute onwards, the Hook technique demonstrated significantly better chest expansion compared with the EC and TE techniques (p < 0.001). Gastric distension was least frequent with the Hook grip (2.7%) and highest with the TE technique (70.3%) (p < 0.001). Table 4: Comparison of oxygen saturation and haemodynamic parameters Parameter Time EC Group (Mean ± SD) TE Group (Mean ± SD) Hook Group (Mean ± SD) P value SpO₂ (%) 1 min 100.00 ± 0.00 99.57 ± 0.50 99.78 ± 0.42 <0.001 2 min 99.68 ± 0.47 99.30 ± 0.46 99.78 ± 0.42 <0.001 3 min 99.78 ± 0.42 99.08 ± 0.55 99.76 ± 0.43 <0.001 Heart Rate (beats/min) 1 min 96.97 ± 10.87 101.16 ± 14.82 96.32 ± 10.12 0.160 2 min 98.27 ± 11.42 101.86 ± 14.65 99.11 ± 10.51 0.353 3 min 96.81 ± 11.40 101.65 ± 14.82 96.51 ± 10.32 0.137 Systolic Blood Pressure (mmHg) 1 min 130.97 ± 12.95 136.86 ± 15.57 126.08 ± 8.45 0.001 2 min 131.03 ± 13.18 136.76 ± 15.46 125.62 ± 8.16 <0.001 3 min 131.24 ± 12.81 136.41 ± 15.14 125.14 ± 8.17 0.001 Diastolic Blood Pressure (mmHg) 1 min 81.57 ± 10.87 84.00 ± 9.94 83.46 ± 6.61 0.502 2 min 83.95 ± 7.86 81.92 ± 9.14 81.54 ± 5.82 0.411 3 min 82.76 ± 7.69 81.84 ± 9.12 80.65 ± 5.62 0.493 Oxygen saturation remained above 99% in all three groups throughout the study. Heart rate and diastolic blood pressure did not differ significantly among the groups. Although systolic blood pressure showed statistically significant differences, all values remained within clinically acceptable limits. Overall Findings The Hook grip consistently demonstrated superior performance compared with the EC and Thenar Eminence techniques. It produced significantly higher tidal volumes, improved EtCO₂ values, superior chest rise, and the lowest incidence of gastric distension while maintaining comparable oxygen saturation and haemodynamic stability. The EC grip performed better than the TE technique for most ventilation parameters, whereas the TE technique demonstrated the poorest overall performance

Bag-mask ventilation (BMV) is a fundamental airway management skill that ensures adequate oxygenation during induction of anaesthesia, emergency airway management, and cardiopulmonary resuscitation. The effectiveness of one-hand BMV largely depends on achieving a proper mask seal while maintaining airway patency through an adequate jaw lift. This prospective comparative study evaluated three commonly used one-hand techniques—EC, Thenar Eminence (TE), and Hook grip—and found that the Hook grip provided the most effective ventilation. Baseline demographic characteristics and airway parameters were comparable among the three groups, indicating that differences in outcomes were attributable to the ventilation technique rather than patient-related factors. The primary outcome, tidal volume, was significantly higher with the Hook grip at all time points. At three minutes, the Hook technique achieved a mean tidal volume of 352.16 ± 37.40 mL, compared with 320.81 ± 34.71 mL in the EC group and 258.97 ± 39.73 mL in the TE group (p < 0.001). This suggests that the Hook grip provides a better face-mask seal and more effective jaw lift, thereby reducing air leakage and improving ventilation. The design of the Hook grip, which combines firm mask support with effective mandibular elevation, may explain its superior performance. End-tidal carbon dioxide (EtCO₂), an objective indicator of alveolar ventilation, also favoured the Hook technique. Although no significant difference was observed at one minute, EtCO₂ values were significantly higher in the Hook group at two and three minutes. These findings correspond well with the higher tidal volumes achieved and indicate more efficient ventilation. The absence of an early difference is likely due to similar ventilation immediately after induction before differences between techniques became evident. Clinical assessment further confirmed these findings. Adequate chest rise was observed in all patients during the first minute; however, from the second minute onwards, the Hook grip maintained significantly better chest expansion than both the EC and TE techniques. At three minutes, adequate chest rise was present in 97.3% of patients in the Hook group compared with 91.9% in the EC group and 48.6% in the TE group (p < 0.001). These results indicate that the Hook grip provides more consistent ventilation during sustained one-hand mask ventilation. Another important observation was the markedly lower incidence of gastric distension with the Hook technique. Gastric insufflation occurred in only 2.7% of patients, compared with 27.0% in the EC group and 70.3% in the TE group. Reduced gastric insufflation is clinically important because it lowers the risk of regurgitation, aspiration, and impaired ventilation due to diaphragmatic elevation. The improved mask seal achieved with the Hook grip probably accounts for this advantage. All three techniques maintained oxygen saturation above 99% throughout the study. Although statistically significant differences in SpO₂ and systolic blood pressure were observed, these changes were small and not clinically relevant. Heart rate and diastolic blood pressure remained comparable among the groups, indicating that the superior ventilation achieved with the Hook grip was not associated with adverse haemodynamic effects. The present findings are in agreement with Balafar et al., who also reported superior ventilation success with the Hook grip compared with the EC and TE techniques. Their study demonstrated improved mask seal and ventilation efficiency with the Hook technique, findings that are consistent with the higher tidal volumes, better EtCO₂ values, improved chest rise, and lower gastric distension observed in the present study. Previous studies have similarly shown that inadequate jaw lift and poor mask seal are the main causes of ineffective one-hand BMV, and the Hook grip appears to overcome these limitations by providing a stronger mandibular lift while maintaining an effective seal. The study has several strengths, including its prospective design, equal group allocation, standardized anaesthetic protocol, and the use of both objective (tidal volume and EtCO₂) and clinical (chest rise and gastric distension) measures of ventilation. However, it also has limitations. Being a single-centre study involving only adults with anticipated normal airways, the findings may not be generalisable to obese patients, difficult airways, or emergency settings. In addition, operator fatigue and ease of learning were not evaluated. In conclusion, the Hook grip demonstrated superior performance among the three one-hand BMV techniques. It provided higher tidal volumes, better EtCO₂ values, improved chest rise, and the lowest incidence of gastric distension while maintaining stable haemodynamics and oxygenation. These findings suggest that the Hook grip may be considered the preferred one-hand bag-mask ventilation technique and should be incorporated into airway management training and routine anaesthetic practice. Strengths of the Study • Prospective comparative study with equal allocation of participants. • Standardised anaesthetic protocol and ventilation conditions. • Objective assessment using tidal volume and waveform capnography. • Simultaneous evaluation of clinical and physiological indicators of ventilation. • Direct comparison of three commonly used one-hand BMV techniques. Limitations • Single-centre study. • Moderate sample size. • Only adult patients with anticipated normal airways were included. • Difficult airway and obese patients were excluded. • Operator fatigue and ease of learning were not assessed.

The Hook grip was superior to the conventional EC and Thenar Eminence techniques for one-hand bag-mask ventilation. It produced significantly higher tidal volumes, improved EtCO₂ values, superior chest expansion, and the lowest incidence of gastric insufflation while maintaining satisfactory oxygenation and haemodynamic stability

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