Table 2 Interventions used in the 7 RCTs

Bottino 2018 [20]

Primary respiratory support/

Following extubation

nHFOV: Medin, Olching,

Germany;

nCPAP:

Interface: Short binasal prongs

nHFOV: Flow:7~10 L/min, Frequency: 10 Hz, Amplitude: set interval 10, I: E:1:1.

nCPAP:

NA

90~95%

Klotz 2017 [16]

Backup ventilatory support/

Primary respiratory support

nHFOV/nCPAP: Sophie, Stephan, Gaggenbach, Germany; Leoni plus,

Heinen+Löwenstein, Bad Ems, Germany

Interface: binasal prongs or nasal masks

nHFOV: Frequency: 10 Hz,

Amplitude: was set to achieve clearly visible oscillations of the chest,

MAP: nHFOV and nCPAP were

set at the level equal.

More than two episodes of apnea

or bradycardia per hour; respiratory acidosis with a pH < 7.10; or FiO2 > 0.6 to maintain a

SpO2 > 86%; hypercapnia with pCO2 > 70 mmHg.

86~96%

Lou 2017 [21]

Respiratory support after extubation

nHFOV: SLEbaby5000,

Germany.

nCPAP: Stephan, Germany.

Interface: Short binasal prongs

nHFOV: FiO₂: 0.35~0.40, Frequency: 6~12 Hz, MAP: 5~7 cmH2O, Amplitude: is 2 to 3 times that of MAP, specifically based on visible oscillations of the chest.

nCPAP: FiO₂: 0.30~0.40, PEEP: 4~6 cmH2O, Flow: 8~10 L/min.

More than 4 episodes of apnea per day, or saturation (SpO2) of < 85%, or paO₂ < 50 mmHg, or pCO₂ > 60 mm

Hg.

90~95%

Lou 2018 [22]

Primary respiratory support

nHFOV: SLEbaby5000,

Germany;

BP-CPAP: Fabian, Swiss.

Interface: Short binasal prongs

nHFOV: FiO₂: 0.30~0.40, Frequency: 6~12 Hz, MAP: 6~12 cmH2O, Amplitude: is 2 to 3 times that of MAP, specifically based on visible oscillations of the chest.

BP-CPAP: FiO₂: 0.30~0.40, lower/higher PEEP: 5/12~15 cmH2O.

More than 4 episodes of apnea per day, or when FIO₂ > 0.5, saturation (SpO2) of < 85%, or paO₂ < 50 mmHg, or pCO₂ > 60 mm

Hg.

90~95%

Malakian 2018 [23]

Primary respiratory support

nHFOV: Medin, Olching,

Germany;

nCPAP: Infant Flow-driver device

Interface: Short binasal prongs

nHFOV: MAP: 4~8 cmH₂O, Frequency: 5 Hz, Amplitude: MAP: 3 cmH₂O, FiO2:0.4~0.6.

nCPAP: PEEP: 4~8 cmH2O, FiO2:0.4~0.6

at least one of the following: pH ≤7.20 and PaCO2 ≥ 60 mmHg, PaO2 ≤ 50 mmHg with a fraction of inspired oxygen of ≥0.6 or recurrent

apnea with ≥3 episodes per hour associated with bradycardia, or a single episode of apnea that

required bag-and-mask ventilation

≥ 90%

Mukerji 2017 [24]

Following CPAP failure

nHFOV: Drager VN500, Lubeck, Germany;

BP-CPAP: SiPAP, Carefusion, USA.

Interface: Short binasal prongs or nasal masks

nHFOV: FiO₂: < 0.6, Frequency: 6~14 Hz, MAP: 8~10 cmH₂O, Amplitude: were adjusted to achieve palpable/visible chest vibrations.

BP-CPAP: FiO₂: < 0.6, lower/higher PEEP: 5~7/8~10 cmH₂O.

Intubation 7 days post randomization, Not specifically described.

90~95%

Zhu 2017 [25]

Primary respiratory support

nHFOV: Medin, Olching,

Germany;

nCPAP: Stephan, Germany

Interface: Binasal prongs

nHFOV: Flow:8~12 L/min, Frequency: 6~12 Hz, Amplitude: 7~10.

nCPAP: PEEP: 6 cmH2O.

PaCO2 > 60 mmHg with pH < 7.20, or more than 3 episodes of apnea per hour

that required bag and mask ventilation, or hypoxia (FiO2 > 0.5 with PaO2 < 50 mmHg), or pulmonary hemorrhage.

90~94%

Zhu 2017 [26]

Primary respiratory support

nHFOV: Medin, Olching,

Germany;

nCPAP: Fabian, Swiss

Interface: Binasal prongs

nHFOV: Flow:8~12 L/min, Frequency: 6~12 Hz, Amplitude: 6~10, FiO2:0.25~0.6.

nCPAP: PEEP: 5~8 cmH2O, FiO₂:0.25~0.6

FiO2 > 0.5 with PaO2 < 50 mmHg; PaCO2 > 60 mmHg with pH < 7.20; Frequent apnea episode (> 3/h)

88~93%