• Return of spontaneous circulation (ROSC) [ Time Frame: Day 0 ]
  Proportion of patients who's recovered a spontaneous circulation after CPR
• Alive at hospital admission [ Time Frame: Day 0 ]
  Vital status at hospital admission
• Survival to hospital discharge [ Time Frame: up to 30 days ]
  Vital status at hospital discharge
• Survival at 30 days [ Time Frame: 30 days ]
  Vital status at 30 days
• Neurological functional status [ Time Frame: Day 30 ]
  As measured by using the modified Rankin Scale (mRS). A score equal to 0 = no symptoms at all, A score equal to 1 = no significant disability, despite symptoms ; able to carry out all usual duties and activities A score equal to 2 = slight disability ; unable to carry out all previous activities but able to look after own affairs A score equal to 3 = moderate disability ; requiring some help, but able to walk without assistance A score equal to 4 = moderately severe disbility ; unable to walk without assistance and unable to attend to own bodily needs without assistance A score equal to 5 = severe disability ; bedridden, incontinent and requiring constant nursing care and attention We consired to a score less or equal to 3 will be considered as favourable neurologic outcome
• First recorded rhythm [ Time Frame: Day 0 ]
  First recorded rhythm and rhythm recorded by EMS (asystole, ryhtme without pulse, ventricular fibrillation or ventricular tacycardia and spontaneous circulation)
• Changes in heart rhythm from ventricular fibrillation (VF) [ Time Frame: Day 0 ]
  Proportion of patients who's with changes in heart rhythm from VF to non-VF rhythm and vice versa during the EMS intervention
• Signs of life [ Time Frame: Day 0 ]
  Presence of agonal respirations and other signs of life (pupillary response, movement during CPR) recorded by ALS
• Re-arrest rates [ Time Frame: Day 0 ]
  We calculated the proportion of patients who's recovered another cardiac arrest during CPR (supported by ALS and EMS)
• Non-invasive arterial O2 [ Time Frame: Day 0 ]
  Non-invasive arterial O2 saturation values during CPR recorded by EMS
• End-tidal carbon dioxide (ETCO2) after CPR initiation [ Time Frame: Day 0 ]
  We compared the difference in ETCO2 values between baseline (i.e., within 2 minutes of CPR initiation) and repeated (i.e., within 4 minutes of CPR initiation) measures during the CPR (recorded by ALS and EMS intervention)
• Non-invasive cerebral oximetry (rsO2) [ Time Frame: Day 0 ]
  Non-invasive cerebral oximetry (rsO2) values during CPR repeated (i.e., within 4 minutes of CPR initiation) measures recorded by ALS and EMS intervention
• Left Ventricular (LV) function [ Time Frame: Day 0 ]
  LV function will be measured by echocardiography within 12 hours of ROSC at hospital
• Non-invasive measurement of blood pressure [ Time Frame: Day 0 ]
  Non-invasive measurement of blood (systolic, diastolic and mean blood pressure) pressure during CPR
• Intubation difficulty [ Time Frame: Day 0 ]
  Intubation difficulty assessed by the Intubation Difficulty Scale score. Score equal at 0 will be considered to easy intubation, score between 0 and 5 will be considered to slight difficulty, score more than 5 will be considered to moderate to major difficulty and score equal to infinite will be considered to impossible intubation
• Neuron specific enolase [ Time Frame: Day 0 and 24hours ]
  Serum Neuron specific enolase was measured at admission and 24h after hospital admission
• S100 protein [ Time Frame: Day 0 and 24hours ]
  Serum S100 protein was measured- at admission and 24h after hospital admission
• Arterial Blood gases [ Time Frame: Day 0 ]
  Arterial blood gases (PaO2 partial pressure of oxygen, PCO2 partial pressure of cardon dioxide, pH, HCO3- bicarbonates and SaO2 oxygen saturation) were measured at hospital admission
• Serum lactate concentration [ Time Frame: Day 0 ]
  The serum lactate concentration was measured at hospital admission
• Serum d-dimer concentration [ Time Frame: Day 0 and 24hours ]
  Serum d-dimer concentration was measured at 4hour and 24 hour after admission
• Troponin C serum concentration [ Time Frame: Day 0 and 24hours ]
  Troponin C serum concentration was measured at 4hour and 24 hour after admission
• Creatinine concentration [ Time Frame: Day 0 and 24hours ]
  Serum creatinine concentration was measured at 4hour and 24 hour after admission
• Transaminases concentration [ Time Frame: Day 0 and 24hours ]
  Serum transaminases concentration (ASAT: aspartate aminotransferases and ALAT: alanine aminotransferases) were measured at 4hour and 24 hour after admission
• Imaging [ Time Frame: 12 hours ]
  Head CT will be performed within 12 hours of ROSC. Analysis will include the white to gray matter ratio
• End-tidal carbon dioxide between witnessed and unwitnessed cardiac arrest out-of-hospital cardiac arrest [ Time Frame: Day 0 ]
  We compared the difference in maximum ETCO2 during CPR between values recorded for witnessed and unwitnessed cardiac arrest
• ROSC for witnessed and unwitnessed cardiac arrest [ Time Frame: Day 0 ]
  Proportion of patients who's recovered a spontaneous circulation after CPR between witnessed and unwitnessed cardiac arrest
• Survival to hospital admission for witnessed and unwitnessed cardiac arrest [ Time Frame: Day 0 ]
  Vital status at hospital admission between witnessed and unwitnessed cardiac arrest
• Survival to hospital discharge for witnessed and unwitnessed cardiac arrest [ Time Frame: Up to 30 days ]
  Vital status at hospital discharge between witnessed and unwitnessed cardiac arrest
• Neurological functional status between witnessed and unwitnessed cardiac arrest [ Time Frame: Up to 30 days ]
  As measured by using the modified Rankin Scale (mRS). A score equal to 0 = no symptoms at all, A score equal to 1 = no significant disability, despite symptoms ; able to carry out all usual duties and activities A score equal to 2 = slight disability ; unable to carry out all previous activities but able to look after own affairs A score equal to 3 = moderate disability ; requiring some help, but able to walk without assistance A score equal to 4 = moderately severe disbility ; unable to walk without assistance and unable to attend to own bodily needs without assistance A score equal to 5 = severe disability ; bedridden, incontinent and requiring constant nursing care and attention We consired to a score less or equal to 3 will be considered as favourable neurologic outcome

• Return of spontaneous circulation (ROSC) [ Time Frame: Day 0 ]
  Proportion of patients who's recovered a spontaneous circulation after CPR
• Alive at hospital admission [ Time Frame: Day 0 ]
  Vital status at hospital admission
• Survival to hospital discharge [ Time Frame: up to 30 days ]
  Vital status at hospital discharge
• Survival at 30 days [ Time Frame: 30 days ]
  Vital status at 30 days
• Neurological functional status [ Time Frame: Day 30 ]
  As measured by using the modified Rankin Scale (a mRS score less or equal to 3 will be considered as favourable neurologic outcome)
• First recorded rhythm [ Time Frame: Day 0 ]
  First recorded rhythm and rhythm recorded by EMS (asystole, ryhtme without pulse, ventricular fibrillation or ventricular tacycardia and spontaneous circulation)
• Changes in heart rhythm from ventricular fibrillation (VF) [ Time Frame: Day 0 ]
  Proportion of patients who's with changes in heart rhythm from VF to non-VF rhythm and vice versa during the EMS intervention
• Signs of life [ Time Frame: Day 0 ]
  Presence of agonal respirations and other signs of life (pupillary response, movement during CPR) recorded by ALS
• Re-arrest rates [ Time Frame: Day 0 ]
  We calculated the proportion of patients who's recovered another cardiac arrest during CPR (supported by ALS and EMS)
• Non-invasive arterial O2 [ Time Frame: Day 0 ]
  Non-invasive arterial O2 saturation values during CPR recorded by EMS
• End-tidal carbon dioxide (ETCO2) [ Time Frame: Day 0 ]
  We compared the difference in ETCO2 values between baseline (i.e., within 2 minutes of CPR initiation) and repeated (i.e., within 4 minutes of CPR initiation) measures during the CPR (recorded by ALS and EMS intervention)
• Non-invasive cerebral oximetry (rsO2) [ Time Frame: Day 0 ]
  Non-invasive cerebral oximetry (rsO2) values during CPR repeated (i.e., within 4 minutes of CPR initiation) measures recorded by ALS and EMS intervention
• Left Ventricular (LV) function [ Time Frame: Day 0 ]
  LV function will be measured by echocardiography within 12 hours of ROSC at hospital
• Non-invasive measurement of blood pressure [ Time Frame: Day 0 ]
  Non-invasive measurement of blood (systolic, diastolic and mean blood pressure) pressure during CPR
• Intubation difficulty [ Time Frame: Day 0 ]
  Intubation difficulty assessed by the Intubation Difficulty Scale score. Score equal at 0 will be considered to easy intubation, score between 0 and 5 will be considered to slight difficulty, score more than 5 will be considered to moderate to major difficulty and score equal to infinite will be considered to impossible intubation
• Neuron specific enolase [ Time Frame: Day 0 and 24hours ]
  Serum Neuron specific enolase was measured at admission and 24h after hospital admission
• S100 protein [ Time Frame: Day 0 and 24hours ]
  Serum S100 protein was measured- at admission and 24h after hospital admission
• Arterial Blood gases [ Time Frame: Day 0 ]
  Arterial blood gases (PaO2 partial pressure of oxygen, PCO2 partial pressure of cardon dioxide, pH, HCO3- bicarbonates and SaO2 oxygen saturation) were measured at hospital admission
• Serum lactate [ Time Frame: Day 0 ]
  Serum lactate was measured at hospital admission
• Serum d-dimer [ Time Frame: Day 0 and 24hours ]
  Serum d-dimer was measured at 4hour and 24 hour after admission
• Troponin C [ Time Frame: Day 0 and 24hours ]
  Troponin C was measured at 4hour and 24 hour after admission
• Creatinine [ Time Frame: Day 0 and 24hours ]
  creatinine, ASAT and ALAT were measured at 4hour and 24 hour after admission
• Transaminases [ Time Frame: Day 0 and 24hours ]
  The transaminases (ASAT: aspartate aminotransferases and ALAT: alanine aminotransferases) were measured at 4hour and 24 hour after admission
• Imaging [ Time Frame: 12 hours ]
  Head CT will be performed within 12 hours of ROSC. Analysis will include the white to gray matter ratio

Elevation of the head and thorax, also known as Head-up cardiopulmonary resuscitation (HUP CPR), has been studied extensively in pigs in ventricular fibrillation (VF). HUP combined with active compression decompression and impedance threshold device (ACD+ITD) CPR improves vital organ perfusion and results in a doubling of cerebral perfusion when compared with the same method of CPR in the flat or horizontal plane. HUP CPR enhances the drainage of venous blood from the brain, lowers central venous pressures, reduces intracranial pressures during the decompression phase of CPR, redistributes blood flow through the lungs during CPR, and may reduce brain edema. These mechanisms collectively contribute to improved blood flow and less injury to the brain during CPR. These benefits are due in large part to the effects of gravity on the physiology of HUP CPR. Importantly, HUP CPR is dependent upon a means of generating enough forward flow to adequately pump blood "uphill" to the brain.

In this proposed pilot study, CPR will be performed manually before the patient is placed on a controlled mechanical elevation device (Elegard, Minnesota Resuscitation Solutions LLC, USA). An ITD-16 (ResQPOD-16, Zoll, USA) will be placed on the patient's airway before the head is elevated. Automated CPR will be initiated as soon as feasible using a new automated CPR mechanical compression device that provides full active compression-decompression CPR (LUCAS-AD, Stryker, USA).

The proposed feasibility clinical study will be the first ever to test the fully integrated system of ACD+ITD HUP CPR.

Elevation of the head and thorax, also known as Head-up cardiopulmonary resuscitation (HUP CPR), has been studied extensively in pigs in ventricular fibrillation (VF). HUP combined with active compression decompression and impedance threshold device (ACD+ITD) CPR improves vital organ perfusion and results in a doubling of cerebral perfusion when compared with the same method of CPR in the flat or horizontal plane. HUP CPR enhances the drainage of venous blood from the brain, lowers central venous pressures, reduces intracranial pressures during the decompression phase of CPR, redistributes blood flow through the lungs during CPR, and may reduce brain edema. These mechanisms collectively contribute to improved blood flow and less injury to the brain during CPR. These benefits are due in large part to the effects of gravity on the physiology of HUP CPR. Importantly, HUP CPR is dependent upon a means of generating enough forward flow to adequately pump blood "uphill" to the brain.

Animal studies have shown that HUP CPR must be performed in a specific manner to be effective. For example, conventional standard CPR is insufficient, by itself, for effective HUP CPR. Additional means to enhance circulation are needed, such as concurrent use of the ITD and ACD CPR devices. ACD+ITD CPR alone has been shown to improve hemodynamics and survival with favorable neurologic outcome in several human randomized control trials. Animal studies have shown that HUP CPR is best with the combination of ACD+ITD CPR. Studies have shown that CPR must be initiated before elevating the head. Studies have also shown that HUP CPR is dependent upon the time it takes to elevate the head to the HUP. Elevation of the head and thorax should optimally take place over a 2-minute period of time from a flat position to the maximum head up elevation level in order to optimize cerebral perfusion pressures. Too rapid an elevation of the head and thorax can result in a reduction in cerebral arterial pressure when compared with flat CPR.

In this proposed pilot study, CPR will be performed manually before the patient is placed on a controlled mechanical elevation device (Elegard, Minnesota Resuscitation Solutions LLC, USA). An ITD-16 (ResQPOD-16, Zoll, USA) will be placed on the patient's airway before the head is elevated. Automated CPR will be initiated as soon as feasible using a new automated CPR mechanical compression device that provides full active compression-decompression CPR (LUCAS-AD, Stryker, USA).

The proposed feasibility clinical study will be the first ever to test the fully integrated system of ACD+ITD HUP CPR.

• Device: Head UP Position

  CPR will be performed manually before the patient is placed on a controlled mechanical elevation device who raises the head and thorax, also known as the head-up position (HUP-Elegard, Minnesota Resuscitation Solutions LLC, USA).

  Rescuers will perform CPR as continuously as possible during the placement of the Elegard, with a <10 second pause in chest compressions during the placement of this device. After performing (LUCAS AD + ITD CPR, see other interventions below) for 2 minutes with the head in the 'flat' position, the Elegard device will be turned on and the head will begin to rise as long as the patient is being treated with the ResQPOD-16 and the LUCAS AD. The head will be elevated to approximately 22 cm from the ground to the back of the occiput.

• Device: Impedance Threshold Device
  An an impedance threshold device ITD-16 (ResQPOD-16, Zoll, USA) will be placed on the patient's airway before the head is elevated.
• Device: New Automated CPR
  Automated CPR will be initiated as soon as feasible using a new automated CPR mechanical compression device that provides full active compression-decompression CPR (LUCAS-AD, Stryker, USA).

• No Intervention: Control Group

  During the pre-intervention period, patients will receive standard CPR in the two study groups. Standard CPR will be performed according to the current guidelines.

  The only changes in current practice for the control will be the monitoring of EtCO2 and cerebral oxymetry as early as possible for the firefighter. ETCO2 will be recorded using a small portable ETCO2 monitor (EMMA, Masimo, USA). EMS first responders will receive a specific training in both group to use, recording, and reporting of ETCO2 value during CPR. This device has CE mark (see related CE mark and user manual). Cerebral oximetry will be recorded using a new small portable device (HR500, Nonin, USA). This device allows using an easy to use adhesive sensor with remote Bluetooth connection to a smartphone sized monitor.

• Active Comparator: Assigned Intervention
  During the post-intervention period, patients assigned in the intervention group will receive the evaluated intervention (i.e., HUP and ACD-ITD CPR HUP using the 3 devices in combinations, Elegard, Lucas AD and ITD-16)
  Interventions:

  • Device: Head UP Position
  • Device: Impedance Threshold Device
  • Device: New Automated CPR

Inclusion Criteria:

• Age > 18 years old on enrollment
• Witnessed out-of-hospital cardiac arrest

Exclusion Criteria:

• Obvious pregnancy at inclusion
• Cardiac arrest of traumatic origin (including drowning or hanging)
• Cardiac arrest for which resuscitation seems unjustified (inevitable death, terminally ill irreversible condition, too long duration of cardiac arrest, advance personal directives of no-resuscitation)