Please select the eligibility criteria that correspond to the clinical trial below.
Title: Observational, Cross-over Study of the Positive Distending Pressure Generated by Humidified High Flow Nasal Cannula as Compared to Nasal Continuous Positive Airway Pressure
Brief Summary: The specific aims of this study are to evaluate the amount of high flow nasal cannula (HFNC) gas flow required to generate an equivalent positive distending pressure as that provided by nasal continuous positive airway pressure (NCPAP) of 6 cm H2O, assess the relationships between positive distending pressure, gas flow, oxygen requirement, and patient weight, and lastly, develop an appropriate protocol to be used in the NICU for transitioning patients from NCPAP to an equivalent amount of HFNC.


Options:
A: Inclusion Criteria:

* Preterm infants admitted to the NICU at University Hospital of North Norway, Tromsoe, Norway (single center study)

  * Gestational age (GA) \< 34 weeks
  * Corrected age \< 34 weeks
  * Receiving nasal CPAP for respiratory distress
  * Respiratory "stable": FiO2 \< 30%, pCO2 \< 8,5 kPa and pH \> 7.25.
* GA \< 29 weeks: Respiratory "stable" over last 72 h.
* GA 29-33 weeks: Respiratory "stable" over last 24 h.

Exclusion Criteria:

1. Congenital anomalies
2. Ongoing treatment for hypoglycemia or infection
3. Other intercurrent disease requiring frequent blood sampling
B: Inclusion Criteria:

1. Gestational age between 24 to 34 and 6/7 weeks assessed by the obstetrical team from dating of last menstural period or ultrasound and weight \>1000 g for the initial treatment of RDS or \<35 weeks post extubation or for apnea of prematurity
2. Infants with RDS who will need NRS as initial therapy or after extubation and for apnea of prematurity, 3. written informed consent.

Exclusion Criteria:

1. Significant morbidity apart from RDS including: cardiac disease (not including patent ductus arteriosus \[PDA\]), congenital malformation, or if they had cardiovascular or respiratory instability because of sepsis, anemia or severe intraventricular hemorrhage (IVH),
2. Parents refuse consent.
3. Unavailability of suitable ventilator.
C: Inclusion Criteria:

* Infants born greater than or equal to 28 weeks (28+0) and less than 37 weeks (36+6) gestation
* CPAP pressure of 5 cm H2O
* FiO2 requirement = or \<0.30
* Clinically stable on these CPAP parameters for 24 hours pre-randomization:

  * Respiratory rate less than 60
  * No significant chest recession
  * No apnea requiring bagging and/or
  * Not more than 6 apneas requiring stimulation in the preceding 24 h.
  * Average saturation \> or = 87%
  * Satisfactory ABG (pH\> 7.25, PCO2 \< 60, and Base deficit \< -8)

Exclusion Criteria:

* Life threatening congenital anomalies
* Congenital cyanotic heart diseases
* Congenital airway or chest wall abnormalities
* Pulmonary hypoplasia
* Known or suspected to have a neuromuscular disorder
* Congenital neurological disorder, severe IVH (grade 3 or 4), PVL and hydrocephalus
D: Inclusion Criteria:

* 1) receiving NCPAP ventilatory support at \> 72 hrs. of age and 2) requiring FiO2 21-50% on NCPAP.

Exclusion Criteria:

* FiO2 \>50%, presence of pneumothorax or pleural effusion, anatomical abnormalities of the airway, lungs, or esophagus, or cyanotic congenital heart defect.

Answer: D