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Reduction of Oxygen After Car...

Reduction of Oxygen After Cardiac Arrest

Last Updated: 2025-10-02

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

TERMINATED

Clinical Phase

Total Enrollment

428 participants

Study Classification

INTERVENTIONAL

Study Start Date

2017-12-11

Study Completion Date

2020-08-05

Brief Summary

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The Reduction of oxygen after cardiac arrest (EXACT) is a multi-centre, randomised, controlled trial (RCT) to determine whether reducing oxygen administration to target an oxygen saturation of 90-94%, compared to 98-100%, as soon as possible following successful resuscitation from OHCA improves outcome at hospital discharge.

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Detailed Description

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Currently out-of-hospital cardiac arrest (OHCA) patients who achieve ROSC are routinely ventilated with the highest fraction of inspired oxygen (FiO2) possible (i.e. FiO2 1.0 or 100% oxygen) until admission to an intensive care unit (ICU) - usually a period of 2 to 6 hours post-ROSC.

Post-ROSC oxygen therapy begins in the field by emergency medical services (EMS). EMS typically deliver a high flow of oxygen at rate of \>10L/min (\~100% oxygen), and use a pulse oximeter to monitor oxygen levels (SpO2). Normal SpO2 levels are considered to be 94% to 100%. The delivery of 100% oxygen is then usually continued throughout a patient's stay in the emergency department (ED) and during any diagnostic testing (e.g. computed tomography scans and cardiac angiography). During this time, oxygen is delivered to patients who remain unconscious via a mechanical ventilator, with levels continuously monitored by pulse oximetry and periodically by a blood test called an arterial blood gas (ABG). The ABG measurements include the oxygen pressure in the blood (PaO2) in mmHg. Once a patient is admitted to the ICU, the PaO2 is assessed and the oxygen fraction is typically reduced and then titrated (reduced or increased) on the ventilator to achieve a normal level of PaO2 ("normoxia") of between 80-100mmHg.

The administration of 100% oxygen for the first hours after resuscitation is based largely on convention and not on any supportive clinical data. It has been thought that maximizing oxygen delivery for several hours might be beneficial in a patient who has suffered profound deprivation of oxygen supply ("hypoxia") during a cardiac arrest. In addition, if a lower fraction of inspired oxygen is delivered, there is a perceived risk that the patient might become hypoxic (i.e. SpO2 \<90% or PaO2 \<80mmHg). Until recently, there has been no particular reason to recommend a decrease in oxygen delivery to the post-arrest patient prior to admission to ICU.

However, recent systematic reviews of compelling experimental data and supportive human observational studies indicate that the administration of 100% oxygen can create "hyperoxic" levels in the early post arrest period which may lead to additional neurological injury, and thus result in worse clinical outcome. No randomised control trials have yet tested titrating oxygen administration to lower but normal levels (i.e. "normoxia").

EXACT is a Phase 3 multi-centre, randomised, controlled trial (RCT) aiming to determine whether reducing oxygen administration to target an oxygen saturation of 90-94%, compared to 98-100%, as soon as possible following successful resuscitation from OHCA improves outcome at hospital discharge.

Conditions

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Out-of-Hospital Cardiac Arrest

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

TREATMENT

Blinding Strategy

TRIPLE

Participants Investigators Outcome Assessors

Study Groups

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target SpO2 98-100%

Post ROSC oxygen titrated to maintain SpO2 between 98-100%

Group Type ACTIVE_COMPARATOR

target SpO2 98-100%

Intervention Type OTHER

Prehospital, post-ROSC oxygen maintained at ≥10L/minute of oxygen (equivalent to \~100% oxygen) into SGA/ETT if hand ventilated or 100% (i.e. FiO2 of 1.0) oxygen settings if mechanically ventilated. Patients will continue on treatment to handover in the ED. Between arrival at ED and first ABG in ICU, the oxygen setting may then be decreased provided SpO2 is maintained between 98-100%.

target SpO2 90-94%

Post ROSC oxygen titrated to maintain SpO2 between 90-94%

Group Type EXPERIMENTAL

target SpO2 90-94%

Intervention Type OTHER

Prehospital, post-ROSC oxygen reduced initially to 4L/minute (i.e. approximately 70% oxygen) into SGA/ETT if hand ventilated or an air mix setting if mechanically ventilated. If oxygen saturation remains ≥94% for 5 minutes, the oxygen flow rate will be further reduced to 2L/minute (i.e. approximately 46% oxygen) and hand ventilated to target an oxygen saturation between 90-94%. This treatment will continue to patient handover in the emergency department. Between arrival at ED and first ABG in ICU, oxygen will be titrated to target a oxygen saturation of 90-94%.

Interventions

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target SpO2 98-100%

Intervention Type OTHER

target SpO2 90-94%

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

* Adults (age 18 years or older)
* Out-of-hospital cardiac arrest of presumed cardiac cause
* All cardiac arrest rhythms
* Unconscious (Glasgow Coma Scale \<9)
* Return of spontaneous circulation
* Pulse oximeter measures oxygen saturation at ≥95% with oxygen flow set at \>10L/min or FiO2 at 100%
* Patient has an endotracheal tube (ETT) or supraglottic airway (SGA) (e.g. laryngeal mask airway -LMA) and is spontaneously breathing or ventilated
* Transport is planned to a participating hospital

Exclusion Criteria

* Female who is known or suspected to be pregnant
* Dependent on others for activities of daily living (i.e. facilitated care or nursing home residents)
* "Not for Resuscitation" order or Advanced Care Directives in place
* Pre-existing oxygen therapy (i.e. for COPD)
* Cardiac arrest due to drowning, trauma or hanging

Minimum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Responsible Party

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Professor Stephen Bernard

Professor

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Stephen Bernard

Role: PRINCIPAL_INVESTIGATOR

Ambulance Victoria

Locations

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Royal Adelaide Hospital

Adelaide, South Australia, Australia

Site Status

The Queen Elizabeth Hospital

Adelaide, South Australia, Australia

Site Status

SA Ambulance Service

Adelaide, South Australia, Australia

Site Status