This study is a multi-center, double blind, randomized controlled trial of inhaled nitric oxide (iNO) in children and adults with cardiac arrest (CA). The purpose of this pilot study is to test the feasibility of rapidly randomizing patients to iNO or sham treatment during cardiopulmonary resuscitation (CPR) or shortly after return of circulation (ROC) and evaluate blood biomarkers associated with iNO compared to sham. Return of circulation may refer to return of spontaneous circulation (ROSC) or ROC through extracorporeal cardiopulmonary resuscitation (E-CPR).

Background: Sudden cardiac arrest is a leading cause of death and neurological handicaps but there is no neuroprotective drug which improves outcome. Recently we discovered a blood biomarker of response to a neuroprotective therapy in our pre-clinical model of cerebral ischemia-reperfusion injury. Biomarkers will likely be used, in the future, to assess response to specific neuroprotective drugs and to help titrate drug dose and duration in individual patients.

Inhaled nitric oxide (iNO) has recently been shown to improve return of spontaneous circulation, survival, and neurological outcome in animal models of cardiac arrest. We have therefore started a pilot randomized controlled trial (RCT) and translational biology study of iNO in children and adults with cardiac arrest. This study will help us design future fully powered RCTs of iNO. We will use methods, from our pre-clinical model, to discover blood biomarkers of response to therapy.

Objectives: In patients with cardiac arrest: (1) Test the safety and feasibility of rapidly randomizing patients to iNO or sham during chest compressions, or shortly after return of circulation (ROC), either spontaneous or by extracorporeal life support. (2) Maintain blinding and measure study outcomes for 6 months post-arrest. (3) Use immunoassays, mass spectrometry and fluorometric assays to determine the differences in serum protein, nitrite, and nitrate biomarker concentrations between the two intervention groups and discover blood biomarkers of therapeutic response to iNO.

Patient population and sample size: Pediatric and adult (total N=40) patients with cardiac arrest admitted to 8 intensive care units (ICUs) at 4 hospitals: SickKids, University Health Network - Toronto General Hospital (TGH) and Toronto Western Hospital (TWH) and Unity Health - St. Michael's Hospital (SMH).

Methods: All patients meeting eligibility criteria will be enrolled, during chest compressions or within 6 hours of ROC, using deferred consent. Patients will be randomized to iNO or sham procedures, using a Redcap screening and randomization tool. Registered respiratory therapists will rapidly start the study gas using our blinded study apparatus. Inhaled NO will be started at a dose of 80 ppm via the endotracheal or tracheostomy tube during chest compressions and reduced to, or started at, 20 ppm after ROC. The iNO or sham procedures will be continued for 72 hours, and weaned off over 12 hours, or stopped earlier if the patient is extubated or dies. Using the Utstein data template for cardiac arrest research, we will collect data into an electronic case report form and Oracle database. Survival, cerebral performance category scores and quality of life scores will be assessed at 1 and 6 months following cardiac arrest. Data and documentation will be reviewed intermittently to ensure that we are compliant with Health Canada guidelines for drug trials.

Serum is being collected and banked at 4 time points following cardiac arrest. The concentrations of biomarkers will be measured and compared between the 2 intervention groups.

Progress: This study is funded by the Heart and Stroke Foundation of Canada.

Inclusion Criteria:

To be eligible to participate in this study, an individual must meet all the following criteria:

1. Aged 1 day* to 80 years on the day the study intervention is started
2. In-hospital or out-of-hospital CA with CPR > 5 minutes
3. It is possible to randomize and start the iNO or sham during CPR or within 5 hours of ROC**
4. Mechanically ventilated in a study site ICU

Note: *Age 1 day is defined as 24 hours and a minimum corrected gestational age ≥ 38 weeks.

Note: **ROC refers to either ROSC or ROC via extracorporeal cardiopulmonary resuscitation (E-CPR).

Exclusion Criteria:

An individual who meets any of the following criteria will be excluded from participation in this study:

1. Unwitnessed cardiac arrest
2. Cardiac arrest due to birth asphyxia
3. Pre-arrest poor neurologic function*
4. Already receiving iNO at the time of CA
5. Any condition or diagnosis, in the opinion of the PI, Co-Investigators, or MRPs, in which iNO would have adverse effects on physiology or where the cardiac anatomy and physiology has not yet been adequately assessed
6. Any condition or diagnosis, in the opinion of the PI, Co-Investigators, or MRPs, in which iNO would be indicated as therapy post-arrest
7. CPR duration > 45 minutes; if less than 18 years old, in-hospital CPR duration > 60 minutes**
8. Known pregnancy***
9. Terminal illness ʈ

Note: * Poor neurologic function is defined as CPC ≥ 4 or PCPC ≥ 4.

Note: **CPR duration is defined as total cumulative duration of CPR (i.e., if a patient has multiple arrests with CPR, the duration of these will be added); patients who undergo E-CPR will not be excluded, to maximize recruitment for this feasibility trial.

Note: ***B-HCG screening is not required for enrollment in women of reproductive age, but testing will occur as soon as possible (within 6 hours of enrollment).

Patients who are cannulated to ECMO for cardiorespiratory support will NOT be excluded a priori.

ʈ The MRP knew that the patient was dying pre-arrest

All de-identified individual participant data (IPD) that underlie results in a publication will be shared upon request. The study protocol, and statistical analysis plan will be shared starting 6 months after publication upon request in writing.

Requests for IPD will be reviewed by the study PI and SickKids institute. IPD will be provided to researchers interested in furthering academia and research development only. IPD requests may also be subjected to SickKids' institutional agreements/contracts. IPD mechanism of sharing and types of analysis/data shared will be directed and determined by SickKids' institutional research contracts requirements

6 months after publication

Requests for IPD will be reviewed by the study PI and SickKids institute. IPD will be provided to researchers interested in furthering academia and research development only. IPD requests may also be subjected to SickKids' institutional agreements/contracts. IPD mechanism of sharing and types of analysis/data shared will be directed and determined by SickKids' institutional research contracts requirements.

The nitric oxide delivery device is covered with a secure shroud and Respiratory Therapists (RTs) are able to safely administer the nitric oxide or sham and document nitric oxide dose and their delivery device checks and monitor for adverse effects according to there clinical standard of care throughout the study intervention. The RTs also document whether there has been a unmasking of the intervention every 12 hours.