Tidal volume according to the 4-point sealing forces of a bag-valve-mask: an adult respiratory arrest simulator-based prospective, descriptive study

Abstract

Background For adequate ventilation during bag-valve-mask ventilation, rescuers should ensure a proper mask seal using the one-handed or two-handed technique. Little is known about the magnitude of sealing forces of a bag-valve-mask needed for adequate ventilation. This study aimed to explore the effect of the 4-point sealing forces of a bag-valve-mask on tidal volume while using the one-handed technique, focusing on the moderating effect of C length (the distance from the thumb to the index finger in the C shape of the one-hand EC grip). Methods A prospective, descriptive simulation study was conducted. A convenience sample of 125 undergraduate paramedic students from two universities was recruited. A self-reported questionnaire was used to collect subjective variables. Tidal volumes, 4-point sealing forces of the mask, peak pressure, and C length of the C shape in the one-hand EC grip were measured using the mechanical lung model under a simulated adult respiratory arrest. Hierarchical regression analysis was used to determine the moderating effect of C length on tidal volume in bag-valve-mask ventilation. Results The average C length, peak pressure, and tidal volume were 7.54 (± 1.85) cm, 11.62 (± 5.40) cmH2O, and 321.66 (± 135.18) mL, respectively. The average range of the 4-point sealing forces was 0.03–0.69 N. The apex sealing force was the weakest among the 4-point sealing forces. Hierarchical regression analysis demonstrated that tidal volume accounted for 62.7% of the variance by C length, peak pressure, and apex sealing force during bag-valve-mask ventilation (F = 9.676, p < 0.001). C length moderated the effect of the apex sealing force and peak pressure on the tidal volume, meaning the higher the peak pressure and apex sealing force, the more the tidal volume and the longer the C length. Conclusion This first simulation study measuring the 4-point sealing forces during bag-valve-mask ventilation provides effective advice that can be adopted in clinical practice without side effects and underpins the importance of continuous retraining and assessment focused on individual physical characteristics, such as C length and bag-valve-mask sealing forces.

Potential Maneuvers for Providing Optimal Tidal Volume Using the One-Handed EC Technique

“…Among the 4-spot adhesion strengths, the force at the bottom contact point was lower than that measured at the right and left of the mask. However, the bottom sealing force was the highest and that the apex sealing force was the weakest, which was in line with the results of Uhm and Kim [ 24 ]. Given the paucity of investigations that analyzed the 4-spot adhesion strength between the mask and face, it was difficult to explain the disparities between the findings.…”

“…This was the result of controlling for gender, grade, and orientation of the hand that sealed the mask. This result is in the same context as a study that emphasized a higher sealing force between the thumb and index finger compared to the existing EC technique [ 11 ] and a study that the ventilation increased as the distance between the thumb and index finger increased [ 20 , 24 ]. However, to accurately identify the cause of these results, follow-up studies are needed.…”

Effects of weights applied to the apex of a bag-valve-mask and pinch strength on tidal volume: a prospective simulation study

“…Although previous studies have reported that the factors affecting effective ventilation were sex, height, weight, C length in the E–C technique, handgrip power, hand width, hand length 11 , 16 , 17 , it is difficult to confirm which factors affect BVM ventilation, especially because few follow-up studies use the same variables. Nevertheless, the rescuer’s hand function is important for appropriate ventilation because BVM bagging with the E–C technique requires the hands 11 , 18 .…”

“…To provide appropriate ventilation without side effects, the mask in BVM was improved so that the entire mask could be controlled with one hand by making a power grip on the mask apex to seal the mask to the face well 13 , and the BVM was modified by adding a supplemental internal handle 12 and external handle 14 or using the pediatric BVM for adults 15 . In addition, a study measuring the 4-spot adhesion strength (sealing forces measured at the bottom, left side, right side and apex of the mask) between a mask and a manikin’s face using the E–C technique demonstrated that the tidal volume (Vt) increases when the apex sealing force during BVM ventilation increases 16 . However, it is difficult to apply more force to the apex of the mask when using a one-handed E–C technique for ventilating the patient; therefore, it is necessary to consider shifting the center of gravity to the apex of the mask.…”

“…Based on the results of our previous studies 16 , 20 , we further investigated the effect of ventilation by weighing the apical area for mask adhesion and measuring the pinch strength required to maintain the E–C technique. Thus, this study aims to identify the varying effects on Vt according to four weights (0 g, 100 g, 200 g, 300 g) applied to the apical area of the mask and pinch strength.…”