Please select the eligibility criteria that correspond to the clinical trial below.
Title: Comparison of Regional Ventilation Pattern During High Flow Nasal Cannula Between Conventional Low Flow System Nasal Cannula in Patients With Mild to Moderate Hypoxia
Brief Summary: High-flow nasal cannula (HFNC) that uses heated and humidified oxygen was recently introduced for bedside care. It has been shown to be associated with reduced risks of tracheal intubation rates and mortality in adult hypoxic patients.

The mechanisms of the effects of HFNC are thought to be related to the favorable effects of the heated and humidified gas, the high-flow rate used to minimize the entrainment of room air, and an increase in the ventilation efficiency, including the elimination of nasopharyngeal dead space, positive end-expiratory pressure (PEEP) effects, and improvements in paradoxical abdominal movement. Regarding the effects on lung volume, global ventilation in the lungs increases during HFNC, which is thought to attribute to PEEP effects. However, how regional ventilation is affected during HFNC in comparison with conventional NC remains unknown.

Because PEEP in mechanically ventilated patients improves the regional homogeneity of ventilation, investigators postulated that HFNC via PEEP effects would result in more homogeneous regional distributions in the ventilation changes. Investigators therefore assessed global and regional ventilation in patients with hypoxia receiving care via HFNC using electric impedance tomography and compared these results with conventional nasal cannula.


Options:
A: Inclusion Criteria:

* Presence of chronic obstructive pulmonary disease (COPD) and acute hypercapnic respiratory failure;
* 7.25 \< pH \< 7.35;
* Arterial Partial pressure of carbon dioxide (PaCO2) equal or greater than 55 mmHg;
* Age \> 18 years/old

Exclusion Criteria:

* Invasive mechanical ventilation in the last 60 days
* Use of any form of noninvasive ventilation or high flow oxygen through nasal cannula (HFNT) prior to study enrollment after the onset of acute hypercapnic respiratory failure (AHRF);
* Noninvasive home care ventilation;
* Unstable clinical condition (need for vasopressors for \>24 h, acute coronary syndrome or life-threatening arrhythmias);
* Refusal of treatment;
* Agitation (RASS \>= +2) or non-cooperation (Kelly Matthay \>=5);
* Failure of more than two organs;
* Cardiac arrest;
* Respiratory arrest requiring tracheal intubation;
* Recent trauma or burns of the neck and face;
* Pregnancy;
* Refusal of consent;
* Inclusion in other research protocols.
B: Inclusion Criteria:

* Duration of mechanical ventilation prior to extubation at least 24h
* Planned extubation decided by the physician in charge of the patient after success of a weaning trial
* Patients at high risk of reintubation according to the following criteria: patients older than 65 years, or those having any underlying chronic cardiac or lung disease.

Exclusion Criteria:

* Patient admitted for traumatic brain injury
* Periphal neuromuscular disease as reason for intubation
* Usual lon-term treatment with NIV for chronic desease
* Usual lon-term treatment with CPAP for obstructive apneas syndrome
* Contraindication to NIV
* Unplanned extubation
* Do-not-reintubated order at time of extubation
* Terminal extubation for end of life
* People under legal protection
* Opposition to participate
C: Inclusion Criteria:

* Age \>20 years
* Subjective dyspnea in room air
* SaO2\< 90% in room air
* Oxygen requirement for nasal cannula \< 6 L/m

Exclusion Criteria:

* Unstable vital signs

  * SBP \<90 mmHg
  * DBP \< 60 mmHg
  * Heart rate \> 120 bpm
  * Respiratory rate \> 30 bpm
  * Persistent dyspnea under oxygen therapy using NC
* Severe hypoxia

  * PaO2/FiO2\< 200 mmHg
* Unable to cooperate

  * Delirium
  * Reduced cognitive function
D: Inclusion Criteria:

* Hypoxemic and no hypercapnic acute respiratory failure :
* severe dyspnea at rest with a respiratory rate \>25 breaths/min
* PaO2/FiO2 \<300
* PaCO2 \<45 mmHg,

Exclusion Criteria:

* age \<18 years
* NPPV contraindications
* past history of respiratory chronic disease (COPD, cystic fibrosis...)
* cardiac pulmonary edema
* Pre-defined intubation
* other than respiratory organ failure : systolic pressure \<90 mmHg,current treatment with epinephrine or norepinephrine, decreased level of consciousness ( Glasgow score ≤ 12)
* profound aplasia (white cells count \<1000/mm 3)

Answer: C