Nasal High Frequency Oscillation Ventilation(NHFOV) vs. Nasal Continuous Positive Airway Pressure(NCPAP) vs Nasal Intermittent Positive Pressure Ventilation（NIPPV） as Post-extubation Respiratory Support in Preterm Infants With Respiratory Distress Syndrome:a Multicenter Randomized Controlled Trial
Phase: NA
Conditions: Intubated Infants Were Intend to Extubation Using Noninvasive Ventilation Strategies
Sponsor: Daping Hospital and the Research Institute of Surgery of the Third Military Medical University

1
Nasal High Frequency Oscillation Ventilation(NHFOV) vs. 
Nasal Continuous Positive Airway Pressure(NCPAP) vs 
Nasal Intermittent Positive Pressure Ventilation（NIPPV） 
as Post-extubation Respiratory Support in Preterm Infants 
With 
Respiratory 
Distress 
Syndrome:a 
Multicenter 
Randomized Controlled Trial  
                   
(NCT03181958)
                  
2 September 2021

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ABSTRACT
Background.Various noninvasive respiratory support modalities are available in neonatal critical care 
in order to minimize invasive ventilation. Continuous positive airway pressure (CPAP) is the more 
commonly used but noninvasive positive pressure ventilation (NIPPV) seems more efficacious in the 
early post-extubation phase, although it is not clear if NIPPV may influence longterm outcomes. A 
recent alternative is noninvasive high frequency oscillatory ventilation (NHFOV) which might be 
useful especially in babies needing high constant distending pressure. Preterm neonates may receive 
these respiratory supports for several weeks.Nonetheless, no data are available for the longterm use of 
NIPPV and NHFOV; few data exist on NHFOV and clinical outcomes, although its safety and 
suitability are reported in a number of preliminary studies.
Methods.We designed a blinded, multicenter, three-arms, parallel, pragmatic, randomized, controlled 
trial with a superiority design, investigating the use of CPAP vs NIPPV vs NHFOV during the whole 
stay in neonatal intensive care units in China. Since safety data will also be analyzed it may be 
considered a phase II/III trial.Moreover, subgroup analyses will be performed on patients according to 
prespecified criteria based on their actual lung physiopathology: these subgroup analyses should be 
considered preliminary.At least 1440 neonates are supposed to be enrolled. The trial has been designed 
with the collaboration of international colleagues expert in NHFOV and the Data Monitoring Board is 
also composed by international experts.An interim safety analysis will be performed at the 50% of the 
enrolment. 
Discussion.The study is applying the best trial methodology to neonatal ventilation, a field where it is 
often difficult to do so for practical reasons.Nonetheless, ours is also a “physiological” trial, since 
interventions are applied based on physiological perspective, in order to use ventilatory techniques at 

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their best.The pragmatic design will increase generalizability of our results but subgroup analyses 
according to predefined physiopathological criteria are also previewed in order to have the advantages 
of an explanatory design.Since not all clinicians are well versed in all respiratory techniques, the 
training is pivotal.We intend to apply particular care to train the participating units: a specific 3-month 
period and several means have been dedicated to this end.
Trial registration: NCT03181958 (registered on June 9, 2017)
BACKGROUND 
1.General background
Respiratory distress syndrome (RDS) is the main cause of respiratory failure in preterm 
neonates, its incidence varying from 80% to 25% depending on gestational age. [1] When optimal 
prenatal care is provided, the best approach to treat RDS, according to several recent trials, [2,3] 
consists in providing continuous positive airway pressure (CPAP) from the first minutes of life using 
short binasal prongs or masks, [4,5] followed by early selective surfactant administration for babies 
with worsening oxygenation and/or increasing work of breathing. Any effort must be done to 
minimize the time under invasive mechanical ventilation (IMV). [6] Nonetheless, clinical trials have 
shown that a relevant proportion of preterm neonates fails this approach and eventually need IMV 
during their hospitalization. [7,8,9] The duration of IMV is a well known risk factor for the 
development of bronchopulmonary dysplasia (BPD) - a condition associated with significant 
morbidity and mortality. [10,11]
To minimize the need of IMV, various noninvasive respiratory support modalities are 
available in neonatal intensive care units (NICU). A systematic review has shown that non-
invasive positive pressure ventilation (NIPPV) reduces the need for IMV (within one week from 
extubation) more effectively than CPAP, although it is not clear if NIPPV may impact on the 

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longterm need for ventilation, BPD or mortality.[12] The main drawback of NIPPV is the lack of 
synchronization, which is difficult to achieve and is usually unavailable. A more recent alternative 
technique is noninvasive high frequency oscillatory ventilation (NHFOV) which consists on the 
application of a bias flow generating a continuous distending pressure with oscillations 
superimposed on spontaneous tidal breathing with no need for synchronization. The physiological, 
biological and clinical characteristics of NHFOV have been described elsewhere.[13]
To date, there is only one small observational uncontrolled study about the use of NHFOV 
after extubation in preterm infants.[14] Other relatively small case series or retrospective cohort 
studies suggested safety, feasibility and possible usefulness of NHFOV and have been reviewed 
elsewhere.[13] The only randomized trial published so far compared NHFOV to biphasic CPAP, 
in babies failing CPAP [15] and it has been criticized for methodological flaws and for not taking 
into account respiratory physiology. [16] An European survey showed that, despite the absence of 
large randomized clinical trials, NHFOV is quite widely used and no major side effects are 
reported, although large data about NHFOV safety are lacking. [17] This may be due to the 
relative NHFOV easiness of use but evidence- and physiology-based data are warranted about this 
technique.
2. Need for a physiology-driven trial
The noninvasive respiratory support policy may fail for several reasons such as, for instance, 
apneas, increasing work of breathing and worsening of parenchymal lung disorder. NHFOV might 
be beneficial in this latter case, that is in neonates needing lung recruitment with high distending 
pressure to open their lungs. This may be the case of extremely preterm, BPD-developing 
neonates who have increased airway resistances, while they are subjected to a deranged 
alveolarization and lung growth. Neonates presenting with respiratory acidosis may also benefit 
from NHFOV.

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NHFOV may do so, because it allows to increase mean airway pressure (Paw) avoiding gas 
trapping and hypercarbia, thanks to the superimposed high frequency oscillations. NHFOV also 
provides the advantages of invasive high frequency oscillatory ventilation (no need for 
synchronization, high efficiency in CO2 removal, less volume/barotrauma) and nasal CPAP 
(noninvasive interface, oxygenation improvement by the increase in functional residual capacity 
through alveolar recruitment). Several animal and bench studies investigated the physiology and 
peculiarities of NHFOV [13] and these data should be used to conduct a physiology-guided trial in 
order to avoid errors done in the early trials about invasive high frequency ventilation. [16]
This study will be the first large trial aiming to compare CPAP vs NIPPV vs NHFOV in 
preterm neonates after surfactant replacement and during their entire NICU stay, to reduce the 
total need/duration of IMV. Noninvasive respiratory support is often used for several weeks, 
especially in extremely preterm neonates, but there are no clear data about the longterm effect of 
the different respiratory modalities and ours will be the first study in investigating this issue. Since 
there is a lack of formal data regarding NHFOV safety, some safety outcomes will also be 
considered. Specific subgroup analysis will be conducted for pre-specified groups of patients who 
may most likely benefit from NHFOV, according to the above-described physiological 
characteristics. 
METHODS AND DESIGN
1.Trial design
This will be a blinded, multi-center, three-arms, parallel, randomized, controlled trial with a 
superiority design, conducted in China. Since safety data will also be analyzed it may be 
considered a phase II/III trial. Since the trial will enroll all eligible patients irrespective of their 
lung mechanics/physiopathology and eligibility will be judged on the basis of simple clinical data 

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commonly used in daily NICU care, it may be considered as pragmatic trial. [18] In fact, no 
particular entry criteria or diagnostic procedure will be required to enroll patients; no biological 
samples will be collected and no additional measures will be taken. Conversely, since subgroup 
analyses will be performed on patients defined a posteriori according to their actual lung 
physiopathology, they should be considered explanatory subgroup (preliminary) analyses. [18] 
Results of subgroup analyses will anyway need confirmation in future, specifically designed trials. 
A total of 69 NICUs are included in this trial (Fig.1). All these NICUs belong to 30 provinces or 
cities or autonomous regions of Chinese mainland (apart from Tibet which has been excluded for 
the high altitude). The trial has been designed with the collaboration of an European investigator 
expert in NHFOV (DLD) and the Data Monitoring Board is also composed by independent 
international experts.
Figure 1. Neonatal Intensive Care Units participating to the trial. Different colors represent 
the number of NICU participating in each area.

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2. Study aim and Hypothesis
Our aim is to verify the hypothesis that NHFOV is more efficacious than CPAP or NIPPV to 
reduce the need for IMV in neonates born between 25 and 32 weeks’ gestation, after their first 
extubation and until their final NICU discharge.
3. Inclusion criteria
For a neonate to be included 4 criteria must be fulfilled: (1) gestational age (GA) between 25+0 
and 32+6 weeks (estimated on the postmenstrual date and early gestation ultrasonographic findings); 
(2) assisted with any type of endotracheal ventilation; (3) post-conceptional age < 36 weeks; (4) 
ready to be extubated for the first time (extubation readiness requires fulfilling of all the following 
criteria: a. having received at least one loading dose of 20 mg/kg and 5 mg/kg daily maintenance 
dose of caffeine citrate; b. pH>7.20 and PaCO260 mmHg (these may be evaluated by arterialized 
capillary blood gas analysis or appropriately calibrated transcutaneous monitors [19] – see appendix. 
Venous blood gas analysis cannot be used); c. Paw of 7-8 or 8-9 cmH 2O, in conventional and 
oscillatory ventilation, respectively; [6] d. FiO20.30; e. sufficient spontaneous breathing effort, as 
per clinical evaluation [20])
4. Exclusion criteria
Neonates who never needed intubation and IMV are not eligible for the study; similarly, a 
neonate randomized but never extubated is not eligible in the study. Moreover, neonates with at 
least one of the following criteria are also not eligible: (1) major congenital anomalies or 
chromosomal abnormalities; (2) neuromuscular diseases; (3) upper respiratory tract abnormalities; 
(4) need for surgery known before the the first extubation; (5) Grade IV-intraventricular hemorrhage 
(IVH) [21] occurring before the first extubation; (6) birth weight <600 g; (7) congenital lung 

8
diseases or malformations or pulmonary hypoplasia. More details are available in the appendix.
5. Randomization
Neonates will be randomized and assigned either to CPAP, NIPPV or NHFOV arms with a 
1:1:1 ratio, when patients fulfil all inclusion criteria and extubation is deemed imminent (anyway 
within 1h). Randomization cannot be done earlier. Simple randomization will be done according to 
a computer-generated random number table and will be posted in a specific secured website 24/7 
available. Twins will be allocated in the same treatment group. Infants randomized to one arm 
cannot crossover to the other or vice-versa during the study. Patients will remain under the assigned 
respiratory support until the weaning criteria will be met (see below). In case of intubation, when 
the baby will be extubated, he will receive again his original treatment according to randomization. 
This can be summarized by Fig.2.
Figure 2. Study flow-chart. Neonates will stay on the assigned intervention until the final weaning. 
No cross-over allowed. In case of intubation, when the baby will be extubated, he will receive again 
his original treatment according to randomization.

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6.Blinding
Blinding towards the caregivers is impossible and blinding towards the patients makes no 
sense. However, outcomes’ assessors will be blinded, as endpoints will be recorded by assessors 
not involved in patients’ care: they will review patients’ files masked for the type of treatment. An 
assessor per each participating NICU will be nominated. Moreover, investigators performing the 
final statistical analyses will also be blinded to the treatment allocation.
7. Primary outcomes
The primary outcomes will be: (1) duration of IMV (in days); (2) ventilator-free days (calculated 
as described in the appendix); (3) the number of reintubation. Neonates will be re-intubated if one 
of the following occurs: 
a. severe respiratory acidosis (defined as PaCO2>65 mmHg with pH<7.2); 
b. hypoxia refractory to study intervention (defined as SpO2<90%, with FiO2=0.4 and 
maximal pressures allowed in the study arm – see below) for at least 4h;
c. severe apnea (defined as recurrent apnea with >3 episodes/h associated with heart rate 
<100/min or a single episode of apnea requiring bag and mask ventilation, or associated 
with SpO2<85% and FiO2>0.6); 
d. pulmonary hemorrhage (defined as brightly blood tracheal secretion associated with 
sharp increase in oxygen and Paw and with the occurrence of “white lungs”, new infiltrates 
or consolidations at the chest X-rays or lung ultrasound); 
e. severe respiratory distress (defined as Silverman score >4) for at least 4h;
f. hemodynamic instability, defined as mean arterial pressure <10 th percentile of 
appropriate nomograms [22,23] or anyway need of dopamine (if >5 γ/Kg/min) or 

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dobutamine (if >5 γ/Kg/min) or any dose of noradrenaline, adrenaline, milrinone, nitric 
oxide or other pulmonary vasodilators.
g. cardio-respiratory arrest. 
8. Secondary outcomes
The secondary outcomes will be: (1) airleaks (pneumothorax and/or pneumomediastinum) 
occurred after the extubation; (2) BPD, defined according to the NICHD definition; [24]                   
(3) hemodynamically significant patent ductus arteriosus (PDA), defined according to local NICU 
protocols; (4) retinopathy of prematurity (ROP)> 2nd stage; [25] (5) necrotizing enterocolitis 
(NEC)≥ 2nd stage; [26] (6) IVH>2nd grade; [21] (7) need for postnatal steroids; (8) in-hospital 
mortality; (9) composite mortality/BPD; (10) weekly weight gain (in grams/d) for the first 4 weeks 
of life or until NICU discharge, whichever comes first.
9. Safety outcomes
The safety outcomes will be the following: (1) weekly number of vomiting/d; (2) weekly 
volume of gastric residual (ml/d); (3) weekly number of apneas/d; (4) nasal skin injury (weekly 
defined by a clinical score [27] as: 0 (zero, absence of injury), stage I (non-blanching erythema), 
stage II (superficial erosion), stage III (necrosis of full thickness of skin) – more details in the 
appendix). These outcomes will be averaged over each week for the first 4 weeks of life or until 
NICU discharge, whichever comes first. Finally, (5) Premature Infant Pain Profile (PIPP) score 
[28] will be considered (averaged from values available in the first 48h from the allocation to 
CPAP, NIPPV or NHFOV).
10. Study Intervention
When the neonate had fulfilled the extubation criteria, this latter will take place with a gentle 
intratracheal suction, following local protocols. Upper airways will then be suctioned and 
intervention will be started immediately as follows:

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10.1 Ventilators
-CPAP: CPAP will be provided by either variable flow or continuous flow devices, as 
there is no evidence that one type of CPAP generator would be better than any other.[29]
-NIPPV: NIPPV will be provided by any type of neonatal ventilator able to generate 
enough pressure according to the protocol (see below). Synchronization will not be 
applied, as many currently marketed neonatal ventilators do not provide it for NIPPV.[30]
-NHFOV: NHFOV will only be provided with piston/membrane oscillators able to provide 
an active expiratory phase (that is, Acutronic FABIAN-III, SLE 5000, Loweinstein Med 
LEONI+, Sensormedics 3100A). Other machines providing high frequency ventilations 
will not be used.
Before the beginning of the study all ventilators will be checked to ensure that there is no
malfunction.
10.2 Interfaces
CPAP, NIPPV and NHFOV will be administered through short, low-resistance binasal 
prongs and/or nasal masks, since these are supposed to be the best in terms of resistive 
charge and leaks. [4,5] Nasal prongs size will be chosen according to the nares’ diameter as 
the best fitting ones (the largest ones fitting the nares without blanching the surrounding 
tissues) and following manufacturer’s recommendations. Nasal masks will also be 
appropriately sized according to manufacturer’s recommendations. Alternating masks and 
prongs, according to clinical evaluation, is allowed in order to reduce the risk for nasal skin 
injury. Particular care (e.g.: pacifiers, positioning, nursing) will be applied to reduce leaks 
and improve patients’ comfort. These latters will be evaluated through a dedicated 30’ 
observation period when study intervention will be instigated. Non-pharmacological 
sedation with pacifiers and 33% glucose solution will be provided, when needed; no other 

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sedation will be allowed. RAMCannula® are not allowed in the trial due to their resistive 
charge and their relevant pressure leaks. [31,32]
10.3 Ventilatory management 
The three interventions will be managed as follows: 
-CPAP: Neonates assigned to the CPAP group were initiated on a pressure of 5 cmH
2O. 
CPAP can be raised in steps of 1 cmH2O up to 8 cmH2O. If this is not enough to maintain 
SpO2 between 90% and 95%, FiO2 will be increased up to 0.40.
-NIPPV: neonates assigned to the NIPPV group will be started with the following 
parameters: a) positive end-expiratory pressure (PEEP) of 4 cmH2O (can be raised in steps 
of 1 cmH2O to max 8 cmH2O, according to the oxygenation). b) Peak Inspiratory Pressure 
(PIP) of 15 cmH2O (can be raised in steps of 1 cmH2O to max 25 cmH2O, according to 
oxygenation, PaCO2 levels and the chest expansion); maximal allowed FiO2 will be 0.40 
and SpO2 targets will be 90-95%. c) inspiratory time (IT) will be 0.45 – 0.5 sec (according 
to clinicians’ evaluation of leaks and the appearance of the pressure curve: a small 
pressure plateau is required and flow may be set accordingly) and rate will be started at 
30 bpm (can be raised in steps of 5 bpm to max 50 bpm, according to PaCO2 levels). 
-NHFOV: neonates assigned to NHFOV will be started with the following boundaries,
   according to available physiological and mechanical data, as suggested elsewhere:[13] 
a) Paw of 10 cmH2O (can be changed in steps of 1 cmH2O within the range range 5-
16 cmH2O); Paw will be titrated (within the range) according to open lung strategy, 
performing alveolar recruitment, similar to what is done in invasive high frequency 
oscillatory ventilation targeting a FiO2≤25-30%, as published elsewhere.[33] Maximal 
allowed FiO2 will be 0.40 and SpO2 targets will be 90%-95%. b) frequency of 10Hz 
(can be changed in steps of 1Hz within the range 8-15Hz). c) Inspiratory time 50% 

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(1:1).[34] d) amplitude 25 cmH2O (can be changed in steps of 5 cmH2O within the 
range 25-50 cmH2O); [34,35] amplitude will be titrated according to PaCO2. It is not 
strictly necessary to have visible chest oscillations, as PaCO2 elimination during 
NHFOV also occurs in the upper airway dead space.[36] In case of hypercarbia, 
amplitude will be increased first and then frequency will be lowered (within the above-
described ranges), however, if nasal masks are used, the amplitude should be kept at the 
maximum and PaCO2 controlled by frequency titration, as oscillation amplitude using 
masks seems more dampened.[37]
11. Monitoring and concurrent treatments/diagnostic measures
PaCO2 will be measured using arterialized capillary blood gas analysis and/or 
transcutaneous monitoring according to local policies. Transcutaneous monitoring will be 
performed according to the American Association of Respiratory Care guidelines [19] and the 
manufacturer’s recommendations. Frequency of blood gas analysis will be decided by the 
attending clinicians. All neonates will be continuously monitored for SpO2, ECG, heart and 
respiratory rate. To avoid abdominal distention, a feeding tube will be placed in the stomach 
through the mouth and gas will be periodically aspirated according to nurses’ evaluation in all 
study arms. Moreover, the following treatments or tests will be provided: 
Heart ultrasound to evaluate cardiac morphology, pulmonary pressures and PDA, 
within the first 3d of life and subsequently repeated, if needed.
Cerebral ultrasound within 48h of life and weekly thereafter, until discharge, if 
needed.
Routine measures to prevent BPD; routine fluid/nutritional policy; routine caffeine 
therapy.
Placement of umbilical central venous catheter and/or peripherally inserted central 

14
venous lines. Placement of arterial lines if needed, according to local policies.
Routine therapies according to local policies (i.e.: antibiotics, PDA closure drugs…).
In general, routine medical care and nursing will not be changed because of the study, out of 
the trial intervention; the clinical care will be identical in the three study arms. No additional blood 
samples are required for this study.
12. Weaning from study interventions
The study intervention will be progressively weaned, according to clinical evaluation and 
respecting the following guidelines: 
oin the CPAP arm, pressure will be reduced by 1 cmH
2O steps down to a minimum of 
3 cmH2O;  
oin the NIPPV arm, PIP and PEEP will be reduced by 1 cmH
2O steps down to a 
minimum of 3 and 5 cmH2O, respectively. Similarly, frequency will be reduced to a 
minimum level of 20 bpm in steps of 5 bpm.
oin the NHFOV arm, amplitude will be reduced to the minimum initial level of 20 
cmH2O and Paw will be reduced by 1 cmH2O down to a minimum of 3-5 cmH2O 
(depending on the ventilator used). 
The study intervention (CPAP, NIPPV or NHFOV) will be stopped when the above-described 
minimum parameters are reached and maintained for at least 48h with the following: (1) FiO2≤0.25; 
(2) Silverman score <3; (3) no apneas or bradycardia without spontaneous recovery. If a baby will 
desaturate (SpO2<85% with FiO2>25%) or has relevant dyspnea (Silverman≧3) or more than 3 
apneas/d, the intervention (CPAP, NIPPV or NHFOV) will be restarted for at least 48h and then re-
evaluated. The end of study intervention may occur at any time during hospitalization if the above 
described criteria are met. When study interventions end, the neonate may be placed under low flow 
oxygen therapy (max 1 L/min), if needed, according to clinicians’ evaluation and local protocols. 

15
Anyway, when a post-conceptional age of 36 weeks is reached, if the patient still needs noninvasive 
respiratory support, he/she will be shifted to CPAP and managed according to clinical evaluation 
and local policies.
13. End of the study
A patient may exit from the study for any of the following reasons:
1. Death.
2. In any case, when the 36 weeks’ post-conceptional age is reached.
3. If parents or guardians withdraw an already given consent for the participation (in that 
case the patient will keep receiving the whole routine clinical care; data acquired will 
be immediately destroyed).
14. Training
Since not all clinicians are well versed in all respiratory techniques and, particularly, NHFOV 
is a relatively new technique, the training is capital for the trial success. The protocol will be diffused 
between participating centers at least 3 months before the study begins. One investigator (YS) will 
explain the study protocol in an in-person meeting with all investigators. During the 3 months, 
clinicians will familiarize with the protocol and the respiratory techniques and an expert in NHFOV 
(DLD) will be available to solve any doubt. A dedicated social media chat has been set to facilitate 
these contacts. Moreover, an expert in NHFOV (DLD) will conduct a webinar teaching about the 
technique and will personally visit some participating NICUs. These actions will happen during 
Oct-Dec 2017. The trial is supposed to actually start in January 2018.
15. Sample size calculation
It is difficult to calculate a sample size, since this is the first trial to investigate CPAP vs 
NIPPV vs NHFOV in post-extubation phase in preterm babies. However, a previous prospective, 
cohort, non-randomized, pilot study comparing post-extubation NIPPV and NHFOV in preterm 

16
neonates provided data about the primary outcome “duration of mechanical ventilation”. This 
study showed a reduction of 30% for babies receiving NHFOV, as compared to those treated 
with NIPPV.[38] A randomized trial of NIPPV vs CPAP by Ramanathan et al. showed a similar 
reduction.[39] Since these trials have not the same design of ours, we decide to be more prudent 
and we aimed a difference of 20% in the duration of mechanical ventilation. Considering an alpha-
error of 0.05 (with a Bonferroni correction at 0.017) and a power of 95%, 480 neonates should be 
enrolled in each arm (with a 1:1:1 design). Thus, a total of at least 1440 neonates will be enrolled. 
Sample size calculation has been performed with GPower3.1.9.3.[40]
16. Data collection
All data can be obtained from the clinical notes. Data will be recorded in real time on web-
based case report forms provided by OpenCDMS. The website will be tested with fictitious data 
before the actual enrolment. Data will be entered by an assessor per each center. Assessors will be 
research nurses or local investigators blinded to the study intervention and not involved in 
patients’ care. Access to the form will be secured and patients will be de-identified. Clinical 
information will be collected at the following time-points:
1. Before the intervention begins: information on eligibility; baseline clinical informations, 
respiratory diagnosis, critical risk index for babies-II (CRIB-II) score.[41]
2. Following study intervention: ventilatory parameters, SpO2, blood gas values before the 
extubation if available. PaO2, PaCO2, SpO2 and pH between 6h and 24h from the extubation. 
3. Follow-up: NICU length stay, duration of IMV, number of reintubation, ventilator free 
days, duration of oxygen therapy, duration of the study intervention (CPAP, NIPPV or NHFOV), 
airleaks, PDA, BPD, ROP >2nd stage, NEC≥2nd stage, IVH>2nd grade, need for postnatal steroids, 
in-hospital mortality, composite mortality/BPD, weekly weight gain (in grams/d) for the first 4 
weeks of life or until NICU discharge, whichever comes first. Moreover, the following safety data 

17
will be recorded: weekly number of vomiting/d, weekly volume of gastric residual (ml/d); weekly 
number of apneas/d; nasal skin injury (weekly defined by a 1-2-3 clinical score [27]). These 
outcomes will be averaged over each week for the first 4 weeks of life or until NICU discharge, 
whichever comes first. Finally, PIPP score [28] will be recorded in the first 48h from the 
allocation. Abdominal circumference at 48h and 96h from the instigation of CPAP, NIPPV or 
NHFOV will also be recorded.
17. Statistics
Data analysis will be performed blindly to the type of treatment received. An intention-to-
treat analysis will be applied. An interim analysis will be performed at 50% of the enrolment by 
the Data Monitoring Board. First, data will be checked for normality using Kolmogorov-Smirnov 
test and results will be presented as odds ratio (OR) and 95% confidence interval (CI) or adjusted 
OR and 95%CI, and mean ± standard deviation or median [quartiles], as appropriate.
Univariate logistic or linear regressions will be performed, according to the type of variable, 
as appropriate. Univariate Cox’s proportional regression will be used for mortality and the 
duration of IMV. Multivariate regressions will also be performed for selected outcomes, if needed 
(that is, if a baseline characteristic differs between the two arms with a p<0.2 at the univariate 
analysis the results will be adjusted for that variable). For each multivariate analysis, 
multicollinearity will be previously checked considering condition index of Eigenvalues and 
Variance Inflation Factor.[42,43] p-values <0.05 will be considered statistically significant.
The following sub-group analysis will be performed:
1. Analysis for babies 28 weeks’ gestation.
2. Analysis for babies who have been invasively ventilated for at least 1 week from birth.
3. Analysis for babies with PaCO2>50mmHg before the extubation or at the 6h or 24h after 
extubation.

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17. Data Monitoring Board 
The Data Monitoring Board will analyze all data in an interim analysis at 50% of the trial 
enrolment. The board will be composed by one epidemiologist, three international neonatologists 
or pediatric intensivists experts in respiratory care and one Chinese neonatologist not involved in 
patients’ care.
DISCUSSION
1.On the trial methods 
Ours is a study trying to apply the best trial methodology to neonatal mechanical ventilation, a 
field where it is often difficult to do so for practical reasons (blinding difficulties, long study times, 
difficult recruitment, lack of funding). Nonetheless, ours is also a “physiological” trials, since 
interventions are applied based on physiological perspective, in order to achieve the best use of the 
different ventilatory techniques. This has been often neglected in the past, but we are exploiting the 
previous bench and in vivo mechanical data [13] in order to optimize the use of NHFOV. Therefore, 
we hope to provide high quality data, although further trials may be required, as this is the first large 
trial on NHFOV. 
Moreover, we applied a pragmatic design in order to increase generalizability of our 
results.[18] This means enrolling many babies in the common daily NICU care, irrespective of their 
actual mechanical and biological lung condition, without any particular test prior to enrolment. 
However, a pragmatic design may also lead to dilute the effect of the interventions and mask their 
effect on a particular type of patients. This is the reason why we also previewed three subgroup 
analyses according to predefined criteria in order to identify patients (a posteriori) for their 

19
physiopathological characteristics. Thus, in the subgroup analyses we intend to have also the 
advantages of an explanatory design.[18] However, results of these subgroup analyses, if promising, 
will unavoidably require further confirmation in subsequent specifically designed trials. 
2. Ethical considerations
This trial is worth to be conducted given the uncertainty about the superiority of one 
respiratory technique over the others, especially for babies at highest risk. Moreover, NHFOV 
might be actually superior to the other techniques, as we may hypothesize this from the currently 
available data.[13] NHFOV has been already studied in preliminary cross-over trials, in bench and 
animal studies,[13] while invasive HFOV is often used for severe respiratory failure. NIPPV has 
been studied in several randomized controlled trials enrolling smaller population and/or without 
triple comparison against CPAP and NHFOV.[12] Thus, the tested interventions are not totally 
new and there is a great drive towards noninvasive ventilation in NICU care: this study is a new 
step within this framework. 
Thus, the risks for babies are minimized and the monitoring will quickly report any possible 
problem. Out of the studied intervention, the participation to the study will not change the routine 
clinical assistance. Data will be anonymously recorded and secured and accessible only to the 
investigators and to the parents/guardians. In no case the recorded data will be used for purposes 
out of those specified in the trial protocol. Moreover, the trial is only funded by a public Chinese 
research program, thus it will not have external industrial influences and has the merit to try filling 
the lack of public funding for neonatal ventilation trials.[44]
3.Publication policy
Study results will be presented to each investigator by teleconference and/or e-mail. If 
possible an investigator meeting in occasion of one of the major congresses in the field of 
pediatrics or critical care (the European Society for Pediatric Research or European Society 

20
for Pediatric and Neonatal Intensive Care Congresses or the Pediatric Academic Societies 
Meeting) will be organized. Data will be also partially presented at these meetings. 
Abstracts and manuscripts will be circulated between all investigators for revision and will 
be approved by all authors in their final version. All manuscripts will be authored by a 
group authorship: full results will be published in a major journal in the field of pediatrics 
or critical care. Authorship criteria of the International Committee of Medical Journal 
Editors will be followed.
4.Appendix
4.1 Clarifications for exclusion criteria
Neonates who never needed intubation and IMV are not eligible for the study; similarly, 
a neonate randomized but never extubated is not eligible. This means that, if a randomized 
neonate is not actually extubated within 1h, because there has been a worsening of his 
conditions or death, he is excluded from the study. Randomization must be done as close as 
possible to the extubation, once all inclusion criteria are fulfilled (see above), and anyway 
within 1h from the actual extubation.
Some exclusion criteria are represented by congenital disorders. When a patient is 
affected by these disorders his biology and physiology are significantly deranged: they are 
not eligible and will not be randomized. If the condition has been discovered/suspected after 
the randomization but before the study inclusion (that is, before extubation), they will not 
receive the study intervention and will not entry in the study. If one of these conditions is 
diagnosed after the inclusion in the study, the neonate will be excluded a posteriori. This is 
the case of neonates with major congenital anomalies, chromosomal abnormalities, 
neuromuscular diseases, congenital upper respiratory tract abnormalities and congenital lung 
diseases or malformations or hypoplasia. Examples of these conditions are: genetic 
syndromes, surfactant protein deficiency, congenital adenomatous pulmonary 
malformations, congenital diaphragmatic hernia or sequestration, congenital hypoventilation 

21
syndrome, pulmonary hypoplasia or any metabolic disease. Same applies for the need for 
surgery anticipated antenatally or before the first extubation, as this is usually related to 
congenital malformations. These neonates are not eligible and will not be randomized. If the 
condition has been discovered/suspected after the randomization but before the study 
inclusion (that is, before extubation) they will not receive the study intervention and will not 
entry in the study. If a surgery will be needed later during the NICU hospitalization for other 
reasons (for instance for PDA ligation or NEC), the patient will regularly continue the trial. 
Conditions needing surgery will be noticed amongst the outcomes.
Grade IV-IVH known before the first extubation is a significant risk factor for prognosis 
and for quality of life. Continuing the NICU care in this situation may be considered 
unethical, depending to different local settings, cultures, ethical and religious beliefs. This 
may significantly impact on the trial outcomes. These neonates are not eligible and will not 
be randomized. If grade IV-IVH has been discovered/suspected after the randomization but 
before the study inclusion (that is, before extubation), they will not receive the study 
intervention and will not entry in the study. If Grade IV-IVH will be diagnosed after the 
study inclusion, the patient will continue the study regularly and this will be noticed 
amongst the outcomes.
4.2 List of study definitions/assessments (in alphabetical order) 
Antenatal steroids. Antenatal steroid prophylaxis will be considered complete if two 12 mg-
doses of betamethasone 24h apart and between 1 day and 7 days before the delivery had been 
given.
Blood gas analysis. Blood gas values may only be obtained in following three ways (venous 
blood gas analysis is not allowed in the study).
-Arterial blood from indwelling arterial lines, if one of these was placed for clinical 
reasons. As these are likely to be unavailable in the majority of cases, the following 
two alternative techniques may be used.
-Arterialized capillary blood gas analysis is performed, warming a patient’s heel for 
10’ and collecting 200 µL of blood into a heparinized micro-tube. This must be 

22
analyzed by a blood gas analyzer within 5’. Blood gas analysis will be obtained upon 
attending neonatologist decision.
-Transcutaneous blood gas monitoring will be performed according to American 
Associations of Respiratory Care guidelines [19] and the device manufacturer’s 
recommendations and using an electrode temperature of 44 °C for a short time (max 
10-15min). Particular care must be provided to avoid skin injury in extremely 
preterm neonates: in some cases, a temperature of 42°C may be more suitable.
BPD definition [24] for neonates 32 weeks’ gestation , as described in Fig.3. 
Figure 3. Current bronchopulmonary dysplasia definition [24]. The figure represents the 
algorythms to apply the definition only in babies 32 weeks’ gestation, as these are those 
enrolled in the trial.  

23
Clinical Risk Index for Babies (CRIB-II) score. [41] This is an estimator of the clinical 
severity at the NICU admission. CRIB-II score considers 4 variables: birth weight, GA, base 
excess within the 1sth of life and temperature at the admission. An online tool will be used to 
calculate the score.
Time on CPAP/NIPPV/NHFOV. Number of days spent under these respiratory supports will 
be registered and rounded to the closest entire number.
Gestational age (GA). GA is determined based on last menstrual period or early ultrasound 
scan (within the first trimester). If a discrepancy of more than 2 weeks exists, the early 
ultrasound scan will be chosen. 
Nasal injuries. These are classified by using a clinical score [26] as stage I (non-blanching 
erythema), stage II (superficial erosion), stage III (necrosis of full thickness of skin) in the skin 
area in contact with nasal prongs, as described elsewhere [27]. The score will be 0 (zero), in 
case of absence of any injury.
Premature Infant Pain Profile (PIPP) score, as described elsewhere. [28]
Pulmonary hypoplasia. This will be clinically defined if anamnestic (prenatal findings: small 
lung volume), imaging (diffuse chest x-ray opacity or hypo-density) and clinical data 
(extremely low gestational age, olygo-anhydramnios, severe pulmonary hypertension, 
refractory hypoxia) are present. Pulmonary hypoplasia usually does not allow survival.
Respiratory main diagnosis. A respiratory main diagnosis that required IMV (surfactant 
administration) has to be given according to the following criteria. RDS: respiratory distress 
appearing within the first 24h of life, with complete, sustained, and prompt response to 
surfactant or lung recruitment or both; additional non-mandatory criteria are lung imaging 
(chest X-rays or ultrasound, according to local policies) supporting the diagnosis or lamellar 
body counts≤30 000/mm³, or both.[45] Pneumonia: broncho-alveolar lavage fluid or blood 
positive culture or C-reactive protein and/or procalcitonin beyond the normal values, together 

24
with radiological signs of infection(infiltrates and/or consolidation and/or loss of aeration).[46] 
Sepsis (international pediatric sepsis definition): presence of systemic inflammatory 
response syndrome (SIRS) together with a suspected or proven (by positive culture, tissue 
stain, or polymerase chain reaction test) infection caused by any pathogen or a clinical 
syndrome associated with a high probability of infection.[47] Infection is suspected according 
to anamnesis, clinical exam, imaging or laboratory tests.[47] Evidence of SIRS is given by the 
presence of at least two of the following four criteria, one of which must be abnormal 
temperature or leukocytes: 
Core temperature >38.5°C or <36°C. 
Tachycardia, defined as a mean heart >180 bpm in the absence of 
external stimulus, chronic drugs, or painful stimuli; or otherwise 
unexplained persistent elevation over a 0.5- to 4-hr time period OR 
bradycardia, defined as a mean heart rate <100 bpm in the absence of 
external vagal stimulus, -blocker drugs, or congenital heart disease; or 
otherwise unexplained persistent depression over a 0.5-hr time period. 
Mean respiratory rate >60/min or need for IMV for an acute process 
not related to underlying neuromuscular disease or the receipt of 
general anesthesia. 
Leukocyte count elevated or depressed or 10% immature neutrophils.  
Meconium aspiration syndrome (MAS): presence of meconium-stained amniotic fluid and 
secretions upon tracheal suctioning with onset of respiratory distress early from birth and chest 
X-rays or lung ultrasound typical for MAS.[48] Neonatal ARDS: defined as per the 
international Montreux definition.[45]
Ventilator free days defined as the number of days spent in the NICU without IMV. One point 
is given for each day during the NICU stay that patients are both alive and free of mechanical 
ventilation; in case of death, zero days will be given.[49]

25
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30
LIST OF ABBREVIATIONS
ARDS: acute respiratory distress syndrome; BPD: bronchopulmonary dysplasia; CI: confidence 
interval; CPAP: continuous positive airway pressure; CRIB-II: critical risk index for babies-II; 
GA: gestational age; IMV: invasive mechanical; IVH: intraventricular hemorrhage; MAS: 
meconium aspiration syndrome; NEC: necrotizing enterocolitis; NHFOV: noninvasive high 
frequency oscillatory ventilation; NICU: neonatal intensive care unit; NIPPV: noninvasive 
positive pressure ventilation; OR: odds ratio; PDA: patent ductus arteriosus; Paw: mean airway 
pressure; PIPP: Premature Infant Pain Profile; ROP: retinopathy of prematurity; RDS: respiratory 
distress syndrome; SIRS: systemic inflammatory response syndrome.
DECLARATIONS
Ethics approval and consent to participate
The trial has been approved by the Ethical Committee of the Third Affiliated Hospital of Third 
Military Medical University – Human Research Protection Program (with the n.201721) and 
informed consent will be obtained from parents or guardians antenatally or upon NICU admission. 
The trial is registered in the clinicaltrial.gov registry (ID:NCT03181958) and will be performed in 
accordance with the approved guidelines and regulations of the participating institutions. 
Consent for publication
Not applicable
Availability of data and material
Not applicable for the study protocol. The datasets used and/or analysed during the trial will be 
made available from the corresponding author on reasonable request.
Competing interests
D. De Luca has received research support, travel grants and/or consultancy fee from Carefusion 

31
(now Vyaire), Acutronic and Maquet. Those are industries producing ventilators for neonatal 
ventilations. These companies are not involved at all in the study and will have have any role in 
the conduct of the study; collection, management, analysis, and interpretation of the data; 
preparation, review, approval of the manuscript or decision to submit it for publication.
Funding
The trial is initiated and planned by the researchers and funded by Scientific Research Projects 
unit of Chongqing (Project- cstc2016shms-ztzx13001). Only this public funding will be used for 
the study, teleconferences, DMB meeting and for publication costs. 
This is a non-promoted study and investigators did not receive and will not receive any fee from 
any industry. In no way industry or commercially interested subjects will have access to the data, 
before their publication. 
Authors’ contribution
Both authors equally contributed to the protocol preparation and the paper writing. All authors 
read and approved the final manuscript.
Acknowledgements
NASal OscillatioN post-Extubation (NASONE) study group
A total of 69 Chinese NICUs and 114 investigators members of the study group.
1．Principal Investigator: Shi Yuan*, Jianhui Wang, Department of Neonatology, Children's 
Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child 
Development and Disorders, Key Laboratory of Pediatrics in Chongqing; Department of 
Pediatrics, Daping hospital of Third Military Medical University. Chongqing, 400042, China. 
2．Chen Long, Department of Pediatrics, Daping hospital of Third Military Medical University, 
Chongqing, 400042, China.
3.Xingwang Zhu, Huanhuan Li, Department of Neonatology JiulongpoPeople's Hospital; 
Department of Neonatology, Children's Hospital of Chongqing Medical University,Ministry of 
Education Key Laboratory of Child Development and Disorders, Key Laboratory of Pediatrics in 
Chongqing. Chongqing, 400042,China.

32
4. Xiaoyun Zhong, Sijie Song, Department of neonatology, Chongqing Women and Children 
Health Hospital. Chongqing, 401147, China.
5．Zhang Lan, Department of Pediatrics, Anhui province affiliated Hospital of Anhui medical 
university. Heifei, Anhui, 230000, China.
6．Li Li, Department of Neonatology, Children's Hospital of The Capital Institute of Pediatrics. 
Beijing, 100020, China. 
7. Huiqiang Liu, Xiaomei Tong, Department of Pediatrics, Third Hospital, Peking University. 
Beijing, 100191, China.
8.Xiaojing Xu, LiFeng Cui, Department of Neonatology, the first affiliated hospital of Tsinghua 
University. Beijing, 1000016, China.
9.Ming Yi, Zhoujie Peng , Department of Neonatology, Women and children's hospital, branch of 
Chongqing sanxia central hospital. Wanzhou, Chongqing, 404000,China. 
10. Li Jie, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Chongqing 
Medical University. Chongqing, 400000,China.
11.Dongmei Chen, Weifeng Zhang, Department of Neonatal Intensive Care Unit, Quanzhou 
Children's Hospital. Quanzhou,Fujian,362000,China 
12.Xinzhu Lin, Department of Neonatology, Maternal and Child Health Care Hospital of Xiamen. 
Xiamen,Fujian,361001, China.
13.Wang Bin, Neonatology and Pediatrics Department, Zhujiang Hospital, Southern Medical 
University. Guangzhou,Guangdong, 510000, China.
14.Weimin Huang, Guangliang Bi, Department of Neonatology, Nanfang Hospital, Southern 
Medical University. Guangzhou, Guangdong,510515, China
15.Shaoru He, Yumei Liu, Department of Neonatology, Guangdong Academy of Medical 
Science/Guangdong General Hospital. Guangzhou,Guangdong,510080, China，
16.Yang Jie, Gao Weiwei, Department of Neonatology, Guangdong Women and Children 
Hospital. Guangzhou, Guangdong,510010,China.
17.Wuhua Liang, Yaoxun Wu, Department of Neonatology, Women and Children's Health 

33
Hospital of Yulin. Yulin, Guangxi Zhuang Autonomous Region, 537000,China.
18.Xinnian Pan, Qiufen Wei, Department of Neonatology, Maternal and Children health care 
hospital of Guangxi Zhuang Autonomous Region. Nanning, Guangxi Zhuang Autonomous Region 
530003,China .
19.Yujun Chen, Bingmei Wei, Department of Pediatrics, the Second Affiliated Hospital of 
Guangxi Medical University. Nanning, Guangxi Zhuang Autonomous Region,530007,China .
20.Ling Liu, Department of Neonatology, Guiyang Maternal and Child Health Care Hospital. 
Guiyang, Guizhou, 550003,China.
21.Xinghui Zheng, Department of Neonatology, The first people's Hospital of Zunyi. Zunyi, 
Guizhou, 563000,China.
22.Ding Xu, Wang Fan, Department of Neonatology, the Second Hospital of Lanzhou University. 
Lanzhou, Gansu, 730030, China.
23.Bin Yi, Jingyun Shi, Department of neonatology, GanSu provencial Maternity and Child Care 
hospital. Lanzhou, GanSu, 730050,China.
24.Yuning Li, Li Jiang, Department of Pediatrics, The First Hospital of Lanzou University. 
Lanzhou,Gansu,730000,China.
25. Chunming Jiang, Department of Neonatology,The First Affiliated Hospital of Harbin Medical 
University. Harbin, Heilongjiang, 150000, China. 
26.Chenghe Tang, Department of Neonatology, The First Affiliated Hospital of Xinxiang Medical 
University. Xingxiang, Henan, 453100, China. 
27.Hong Xiong, Huiqing Sun, Wenqing Kang, Dapeng Liu, Neonatal Intensive Care Unit and 
Department of Neonatology, Zhengzhou Children's Hospital, the Children's Hospital of 
Zhengzhou University. Zhengzhou,Henan, 450018, China. 
28.Falin Xu, Department of Neonatology,The Third affiliated Hospital of Zhengzhou University. 
Zhengzhou, Henan 450052, China.           
29.Xing Kaihui, Yang Ning, Department of Neonatal Intensive Care Unit, the Maternal and child 
health hospital of Hainan province. Haikou, Hainan, 570206, China.
30.Fang Liu, Shaoguang Lv, Department of Neonatal Intensive Care Unit, Bethune International 

34
Peace Hospital. Shijiazhuang, Hebei,050082, China.
31.Liu Hanchu, Yuan Wenchao, Department of Neonatology, Wuhan Children’s Hospital, Tongji 
Medical College, Huazhong University of Science & Technology. Wuhan, Hubei,43000 ,China.
32.Rui Cheng, Shen Xian, Department of Neonatology, Children's Hospital of Nanjing Medical 
University. Nanjing, Jiangsu, 210008, China.
33.Hui Wu, Department of Neonatology, the First Hospital of Jilin University. Changchun, 
Jilin,130021, China. 
34.Laishuan Wang, Department of neonatology, Children's hospital of Fudan University. 
Shanghai, 201102, China.
35.Zhenying Yang, Zhang Xiao, Department of Neonatology, Maternal and Children's Healthcare 
Hospital of Taian. Taian,Shandong,271000,China. 
36. Xue Jiang, Department of neonatal intensive care unit, the second hospital of Shandong 
University. Jinan, Shandong, 250033, China. 
37.Zhankui Li, Department of Neonatology, North-West Women and Children's Hospital(maternal 
and Children's Healthcare Hospital of Shaanxi Province). Xian, Shanxi,710061, China.
38.Rong Ju, Wang Jin, Department of Neonatal Intensive Care Unit, the Women and Children's 
\Center Hospital of Chengdu. Chengdu, Sichuan, 610000, China.
39.Wenbin Dong, Department of Newborn Medicine, the Affiliated Hospital of Southwest 
Medical University. Luzhou,Sichuan,646000,China.
40. Ye Xiaoxiu, Department of Newborn Medicine,Hospital Affiliated to Southwest Medical 
University. Luzhou, Sichuan,646000, China.
41.Benqing Wu. Department of Neonatology, Shenzhen People's hospital/the Second Medical 
College of Jinan University.Shenzhen,Guangdong,518020,China. 
42.Zheng Jun, Tian Xiuying, Department of Neonatology, Tianjin Central Hospital of Obstetrics 
and Gynecology. Tianjin,300100, China.
43.Mingxia Li, Yanping Zhu, Department of Neonatology, the first affiliated hospital of Xinjiang 
Medical University. Urumqi, Xinjiang Uygur Autonomous Region ,830011, China.
44.Nuerya Rejiafu, Li Long, Department of Neonatology, People's Hospital of Xinjiang Uygur 

35
Autonomous Region. Urumqi, Xinjiang Uygur Autonomous Region 830001, China.
45.Yangfang Li, Canlin He, Department of neonatology, children's hospital of Kunming medical 
university. Kunming,Yunnan,650228,China.
46.Li Li, HongYing Mi, Pediatric Department, the first people's hospital of Yunnan province. 
Kunming,Yunnan, 650032, China. 
47.Liang Kun, Department of Pediatrics, the first affiliated hospital of Kunming Medical 
University. Kunming,Yunnan,650032,China. 
48.Hong Cao, Linglin Xia, Department of Neonatal Intensive Care Unit, Yan'an Hospital 
Affiliated to Kunming Medical University. Kunming,Yunnan,650032,China.
49.Chuanfeng Li, Department of Neonatology, Women and Children's Health Hospital of Qujing. 
Qujing,Yunnan,655000,China.
50.Zhaoqing Yin, Su Le, Department of neonatology,The people's hospital of Dehong autonomous 
prefecture. Mangshi, Yunnan, 678400, China.
51.Yanxiang Cheng, Department of Neonatology, Yinchuan No.1 people's Hospital Affiliated of 
Ningxia Medical University. Yinchuan, Ningxia,750000,China
52.Liping Shi, Wang Chenhong, Department of Neonatal Intensive Care Unit, The Children's 
Hospital of Zhejiang University School of Medicine. Hangzhou, Zhejiang,310000, China.
53.Jiajun Zhu, Department of Neonatology, Women's Hospital, School of Medicine, Zhejiang 
University. Hangzhou,Zhejiang,310000,China.
54.Zhang Xuefeng, Department of Neonatology, 302 Military hospital of china, People Liberation 
Army of China. Beijing,100000, China.
55.XiRong Gao, Bo Lv, Department of Neonatology, Hunan Children's hospital. Changsha, 
Hunan,410007,China.
56.Liu Chongde, Wang Xiaorong, Department of Neonatology,Women and Children's Hospital of 
Qinghai. Xining, Qinghai,810007,China. 
57.Chen Liping, Li Lin, Department of Neonatology, Jiangxi Provincial Children's Hospital. 
Nanchang,Jiangxi,330006,China.
58.Zhang Chunli, Department of Neonatology,Inner Mongolia People's Hospital. Hohhot, Inner 

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Mongolia,010000,China.
59.Chen Jia, Department of Neonatology, Mianyang central hospital. Mianyang, Sichuan,621000, 
China. 
60.Qiyu Li, Department of Pediatrics, 202 Military hospital of People's Liberation Army of China, 
Shenyang, Liaoning,110000,China.       
61.Lv Qin, Yanhong Li, Infant Intensive Care Unit, Ningbo women and children hospital. Ningbo, 
Zhejiang,315010, China. 
62.Yong Ji,bYanjiang Chen, NICU, Children’s hospital of Shanxi. Taiyuan, Shanxi,030000, 
China. 
63.Jianhua Sun, Jun Bu, Department of Neonatology, Shanghai Children’s Medical Center. 
Shanghai,200127,China. 
64.Danni Zhong, Zongyan Gao, Department of Pediatrics,The First Affiliated Hospital of Guangxi 
Medical University. Nanning, Guangxi Zhuang Autonomous Region,530021, China. 
65.Han Shuping, Xiaohui Chen, Department of Pediatrics, Obstetrics and Gynecology Hospital of 
Affiliated to Nanjing Medical University. Nanjing, Jiangsu, 210001, China.
66. Caiyun Gao, Hongbin Zhu, Pediatric Department, Qinhuangdao maternal and child health care 
hospital. Qinhuangdao, Hebei, 066000, China.
67.Zhenguang Li, Hongwei Wu, Pediatric Department, Xuzhou Children Hospital. Xuzhou, 
Jingsu, 221000, China. 
68.Xiuyong Cheng, Pediatric Department, The first affiliated hospital of Zhengzhou university, 
Zhengzhou, Henan,450000,China. 
69.Juhua Li, Department of Pediatrics, Xianyang children’s Hospital. 
Xianyang,Shanxi,712021,China. 

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