Table 1 Lung volumes and distribution of ventilation under face mask and helmet NIV
| Â | Patient 1 | Patient 2 | ||||
|---|---|---|---|---|---|---|
Clinical history: | 61-year-old female with metastatic small cell lung cancer admitted to the ICU for sepsis and acute hypoxemic respiratory failure | 69-year-old female with acute myelogenous leukaemia admitted to ICU for acute hypoxemic respiratory failure | ||||
| Â | Face mask NIV | Transition (no NIV) | Helmet NIV | Face mask NIV | Transition (no NIV) | Helmet NIV |
 Ventilator | Draeger V500 | n/a | Draeger V500 | BiPap Vision | n/a | Draeger V500 |
 NIV setting (IPAP/EPAP), cm H2O | 12/8 | n/a | 12/8 | 10/8 | n/a | 10/8 |
 Tidal impedance variation (mean, SD) | 1404 (93) | 773 (202) | 1163 (259) | 2123 (259) | 1724 (487) | 2564 (245) |
 Tidal volume, ml (mean, SD) | 392 (26) | 216 (56) | 325 (72) | 375 (46) | 310 (86) | 462 (43) |
 End-expiratory lung impedance (mean, SD) | 550 (126) | 234 (83) | 3022 (147) | 3623 (128) | 1956 (559) | 5203 (212) |
 Computed end-expiratory lung volume above FRC, ml (mean, SE) | 88 (34) | Reference | 778 (38) | 253 (134) | Reference | 574 (140) |
 Proportion of tidal impedance in variation in dorsal lung region (%) | 56 | 50 | 57 | 45 | 42 | 57 |
 Respiratory rate (min−1) | 24 | 31 | 25 | 33 | 32 | 34 |
 Peripheral oxygen saturation (%) | 92 | n/a | 96 | 93 | n/a | 95 |
 Set FiO2* | 0.55 | n/a | 0.4 | 0.5 | n/a | 0.4 |