A Pilot Study Comparing Oxygen Delivery Via Helmet Interface Versus High Flow Nasal Cannula
A Pilot Study Comparing Oxygen Delivery Via Helmet Interface Versus High Flow Nasal Cannula
Our main objective is to collect feasibility data on helmet NIPPV and other clinical elements
 in to eventually prepare for a full scale randomized trial based on findings of this pilot
 study.
Patients with acute hypoxemia leading to respiratory failure are frequently supported by
 endotracheal intubation and mechanical ventilation. Unfortunately an invasive approach to
 support is associated with risks of lung injury, infection, need for heavy sedation, and
 increased mortality. Non-invasive oxygen delivery, by mask (BiPAP or CPAP), high flow nasal
 cannula or helmet interface, is better tolerated and reduces risks associated with invasive
 mechanical ventilation. A growing body of medical literature and clinical experience suggests
 that non-invasive oxygen delivery can prevent the need for endotracheal intubation in some
 patients. This proposal will compare two different modes of non-invasive oxygen delivery:
 helmet and high flow nasal cannula.
Inclusion Criteria:

 1. Age ≥ 18 years

 2. AHRF defined as:

 A ratio of partial pressure of oxygen (PaO2) to fraction of inspired oxygen (FiO2)
 between 100 - 250 mm Hg while breathing O2 from Venturi mask, or other delivery system
 that allows quantification of FiO2 such as Mask-NIPPV or HFNC.

 When no arterial blood gas (ABG) result available, use transcutaneous oxygen
 saturation measurement (SpO2) to impute PaO2 (Appendix A.2 for Table of PaO2 / FiO2
 imputed from SpO2 [Brown 2017]. If no oxygenation data prior to use of Mask-NIPPV or
 HFNC are available, then P/F ratio 100 - 250 on Mask-NIPPV or HFNC meets this
 criterion.

 3. Respiratory rate (RR) ≥24 /min and/or subjective shortness of breath (Modified Borg
 Dyspnea Scale ≥ 2)

 Exclusion Criteria:

 1. P/F Ratio < 100 (Severe ARDS) on quantifiable FiO2

 2. More than 24 hours has elapsed since the patient met criteria for AHRF (Inclusion #2
 and 3, above)

 3. Urgent need for intubation

 Criteria for intubation:

 i. RR>40 ii. Lack of improvement of respiratory muscle fatigue iii. Copious tracheal
 secretions that require frequent suctioning iv. Acidosis with a potential Hydrogen
 (pH) <7.35 v. Acute hypercarbia (PaCO2 > 45 mm Hg) vi. SpO2 < 88% for more than 5
 minutes despite FiO2 and non-invasive support vii. Respiratory or cardiac arrest viii.
 Glasgow Coma Scale ≤ 8

 4. Contraindication to HFNC, Helmet-NIPPV, or Mask-NIPPV

 5. Upper airway obstruction, facial trauma

 6. Copious secretions, airway bleeding, epistaxis or vomiting

 7. Primary cause of respiratory failure is exacerbation of chronic obstructive pulmonary
 disease (COPD) or asthma

 8. Elevated intracranial pressure >20 mm Hg

 9. Home mechanical ventilation except for CPAP/BiPAP used solely for sleep disordered
 breathing

 10. Persistent hemodynamic instability (systolic blood pressure (SBP)<90 or mean arterial
 pressure (MAP)<60 despite IV fluid resuscitation, or norepinephrine dose > 0.1
 mcg/kg/min or equivalent vasopressor dose)

 11. Plan for procedure during which NIPPV or HFNC is contraindicated. Okay to enroll if
 procedure is complete and AHRF persists within 24 hours.

 12. Absence of airway protective gag reflex or cough

 13. Tracheostomy

 14. Lack of informed consent

 15. Pregnancy

 16. Actual body weight exceeding 1 kg per cm of height

 17. Diffuse alveolar hemorrhage

 18. Severe acute pancreatitis as etiology for hypoxemia

 19. Recent upper gastrointestinal surgical anastomosis within the past 30 days

 20. Enrollment in another clinical trial within the past 30 days

 21. Unsuitable for non-invasive ventilation in the judgment of the treating MD

 22. Decision to withhold life-sustaining treatment. Patients with Do-Not-Resuscitate (DNR)
 or No Cardiopulmonary resuscitation (No CPR) order may be enrolled.

 23. Do not intubate order