Structural firefighters are trained to alter their breathing pattern to minimize the use of air in their self-contained breathing apparatus (SCBA) in the event they become trapped. PURPOSE: The purpose of this study was to measure the effects of different breathing patterns on ventilation (VE) to determine if skip breathing (SB) and deep breathing (DB), with and without simultaneously controlled breathing frequency (fb) and tidal volume (TV) decreased VE without decreasing blood oxygen saturation levels (SpO2). METHODS: Sixteen college-aged participants took part in five different 10 min breathing trials consisting of normal breathing (NB), DB, SB, deep breathing modified (DBM) and skip breathing modified (SBM). During all five trials, TV, fb, VE, respiratory exchange ratio (RER), SpO2, and end tidal CO2 (EtCO2) were measured. Participants were instructed to take deeper breaths during the DB trial, and follow a firefighter SB protocol during the SB trial. For both the DBM and SBM trials, the participants were instructed to have a fb half that of their fb during their NB trial, and a TV 1.5 times that of their TV during their NB trial. The difference between DBM and SBM, was that the SBM breathing cycle consisted of two inhales and one exhale, whereas during DBM each cycle consisted of an inhale and an exhale. RESULTS: VE differed significantly among the different breathing techniques (P < 0.001). Specifically, VE (mean ± sd) during NB (9.20 ± 1.93), DB (11.30 ± 4.64), and SB (9.74 ± 3.66) were significantly greater than VE during DBM (6.72 ± 1.20) and SBM (7.04 ± 1.34) (P < 0.01). However, none of the five breathing techniques significantly altered SpO2 (P = 0.56). CONCLUSION: increasing TV from baseline by a greater amount than decreasing fb from baseline during DBM and SBM resulted in a lower VE compared to NB. Importantly, the lower VE achieved with DBM would save 49.6 L of air during a 20 min period of entrapment and extend the air supply 7 min and 23 s. Similarly, the lower VE achieved during SBM would save 43.2 L of air during a 20 min period of entrapment and extend the air supply 6 min and 8 s. Only DBM and SBM have the potential to prolong one's air supply when using a self-contained breathing apparatus.

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