Comparison between physiological effects of noninvasive ventilation (NIV) and high-flow nasal cannula (HFNC)
| NIV | HFNC | HFNC–NIV | ||
| Median (IQR) | Median (IQR) | Median (95% CI) | p-value# | |
| VT global (units) | 3161 (1884–3805) | 2323 (1497–2891) | −678.0 (−947.5– −322.0) | 0.001 |
| VT ROI1 (units) | 887 (657–1033) | 590 (464–774) | −204.5 (−279.5– −122.0) | 0.0007 |
| VT ROI2 (units) | 686 (413–925) | 445 (262–656) | −214.0 (−309.0– −130.0) | 0.0003 |
| VT ROI3 (units) | 743 (498–1008) | 589 (271–909) | −118.5 (−221.5–0.0) | 0.04 |
| VT ROI4 (units) | 444 (318–861) | 450 (286–664) | −93.5 (−200.0–7.5) | 0.06 |
| VT consolidation (units) | 778 (338–1002) | 489 (198–783) | −133.0 (−215.0– −53.5) | 0.004 |
| EELI global (units) | 4083 (2928–5134) | 2921 (1706–4850) | −570.5 (−1649.5–824.0) | 0.4 |
| EELI ROI1 (units) | 842 (646–1144) | 562 (215–1000) | −329.0 (−570.5– −110.0) | 0.01 |
| EELI ROI2 (units) | 960 (469–1406) | 408 (355–1152) | −174.0 (−563.0–79.5) | 0.1 |
| EELI ROI3 (units) | 767 (336–1124) | 618 (370–1251) | −101.0 (−487.0–476.0) | 0.5 |
| EELI ROI4 (units) | 846 (488–971) | 447 (373–738) | −196.0 (−491.5–733.0) | 0.4 |
| EELI consolidation (units) | 899 (767–1144) | 486 (381–946) | −322.5 (−588.5–178.5) | 0.1 |
| Respiratory rate (breaths·min−1) | 24 (22–27) | 23 (21–26) | −2 (−4–4) | 0.6 |
| SpO2/FiO2 ratio | 167 (143–200) | 163 (140–200) | −4.5 (−15.5– −2.0) | 0.001 |
| SpO2 (%) | 100 (98–100) | 97 (96–100) | −2 (−3–0) | 0.010 |
| Heart rate (beats·min−1) | 84 (68–98) | 90 (78–104) | 1 (−2–5) | 0.8 |
| SBP (mmHg) | 119 (108–131) | 125 (113–137) | 3 (−1–11) | 0.2 |
| MAP (mmHg) | 80 (76–89) | 85 (77–94) | 2 (−3–5) | 0.6 |
| Dyspnoea score (0–10) | 5 (0–5) | 5 (2–5) | 0 (−1–1) | 0.7 |
| Patient comfort score (0–10) | 4 (2–5) | 5 (4–7) | 0 (−1–4) | 0.7 |
Bold type represents statistical significance. IQR: interquartile range; VT: tidal volume variation; ROI: region of interest; EELI: end-expiratory lung impedance; SpO2: pulse oxygen saturation; FiO2: inspiratory oxygen fraction; SBP: systolic blood pressure; MAP: mean arterial pressure. #: Wilcoxon signed rank test.