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Table 1 Modelling details for breathing sequences

From: Contemporary portable oxygen concentrators and diverse breathing behaviours -- a bench comparison

Scenario and modelling guidanceBreath rate
EffortNasal Tidal VolumeRin / Rex
cmH2O/ L/sec
mL/ cmH2O
COPD patient, onset of exertion: Progressive increase in breath rate, inspiratory effort amplitude, and expiratory effort contribution, guided by references [13, 14].20–34Figure 2(b)234 mL–700 mL (100% nasal)8 / 1375
Low demand COPD patient at rest: Lower-than-typical volume for adult COPD. From Fig. 1 of reference [15], the lowest minute ventilation for an awake COPD patient in this cohort was 5.1L/min. A chronic stable COPD resting breath rate of 17/min was adopted [16].17Figure 2(a) dashed curve304 mL
(100% nasal)
6 / 1175
COPD patient, reduced nasal fraction: Sleeping COPD patient with average minute ventilation, breathing through both nose and mouth. Oronasal breath partitioning guided by Fig. 4 of [17]: for their subjects over 45 years old, oral proportion was 51% (median) or 45% (mean). An oral proportion within this span was used: 47%. Median ventilation for a COPD patient during REM sleep: 5.9 L/min from Fig. 1 of reference [15]. Mean breath rate during REM for nocturnal desaturators, Fig. 3 of [15]: 17.6/min. Compliance reduced and resistance increased consistent with supine posture and sleep [18].17.6Figure 2(a) solid curve182 mL
(53% nasal, total VT of 343 mL)
12/ 1565
  1. Rin, inspiratory resistance, cmH2O/ L/sec; Rex, expiratory resistance, cmH2O/ L/sec; Crs, compliance of the respiratory system, mL/cmH2O; REM, rapid eye movement; VT, tidal volume