Table 1.
Basic characteristics of the included studies.
| Study | Study type | Country | Settings | Patients | Delivery device | Humidifier | Flow rate (L/min) | FiO2 |
|---|---|---|---|---|---|---|---|---|
| Chandel [9] | Multi-centered observational cohort study | USA | ICU | COVID-19 | Fisher & Paykel Optiflow™ system | MR810 heated humidifier | N/a | N/a |
| Calligaro [11] | Multi-centered observational study | South Africa | ICU | COVID-19 | Hamilton C1 Ventilator, AIRVO™ (Fisher & Paykel) or Inspire O2 FLO | N/a | 50–60 L/min | 0.8–1.0 |
| Hu [4] | Retrospective observational study | China | Respiratory wards | COVID-19 | AIRVO2, Fisher & Paykel | N/a | 30 L/min | 1.0 |
| Panadero [14] | Retrospective observational study | Spain | Intermediate Respiratory Care Unit (IRCU) | COVID-19 | AIRVO2, Fisher & Paykel | N/a | 50–60 L/min | N/a |
| Xu [13] | Mulitcenter retrospective observational study | China | ICU | COVID-19 | Fisher & Paykel | N/a | 30 L/min | N/a |
| Vega ML [7] | Retrospective observational study | Italy | Respiratory wards | COVID-19 | N/a | N/a | 50–60 L/min | N/a |
| Blez [12] | Prospective observational study | France | ICU | COVID-19 | Optiflow® | MR810 heated humidified | 60 L/min | 1.0 |
| Zucman [10] | Retrospective observational study | France | ICU | COVID-19 | Fisher & Paykel | N/a | 50 L/min | 0.8 |
ICU: intensive care unit; COVID-19: coronavirus disease 2019; FiO2: fraction of inspired oxygen; N/a- not available.