Can you deliver accurate tidal volume by manual resuscitator?

One of the problems with manual resuscitators is the difficulty in achieving accurate volume delivery. The volume delivered to the patient varies by the physical characteristics of the person and method. This study was designed to compare tidal volumes delivered by the squeezing method, physical characteristics and education and practice levels.

114 individuals trained in basic life support and bag-valve-mask ventilation participated in this study. Individual characteristics were obtained by the observer and the education and practice level were described by the subjects. Ventilation was delivered with a manual resuscitator connected to a microspirometer and volumes were measured. Subjects completed three procedures: one-handed, two-handed and two-handed half-compression.

The mean (standard deviation) volumes for the one-handed method were 592.84 ml (SD 117.39), two-handed 644.24 ml (SD 144.7) and two-handed half-compression 458.31 ml (SD 120.91) (p<0.01). Tidal volume delivered by two hands was significantly greater than that delivered by one hand (r = 0.398, p<0.01). The physical aspects including hand size, volume and grip power had no correlation with the volume delivered. There were slight increases in tidal volume with education and practice, but correlation was weak (r = 0.213, r = 0.281, r = 0.131, p<0.01).

The tidal volume delivered by a manual resuscitator shows large variations. There were significant differences in the volume delivered by compression methods, but physical characteristics are not a predictor of tidal volume delivery. The manual resuscitator is not a suitable device for accurate ventilation.