During acute coronary syndrome, the American College of Cardiology and the American Heart Association recommend oxygen delivery to patients with less than 90% oxygen saturation. Oxygen therapy in these patients for a duration of at least 6 hours, but also stipulates that it is reasonable to administer oxygen to all acute coronary syndrome patients during the first six hours following the presentation. Hyperoxia also has well-established risks.

Our research hypotheses are:

(I) that current practices tend to use high oxygen flows resulting in high SpO2 levels during acute coronary syndrome.

(II) there is a high rate of desaturation in patients with acute coronary syndrome and an automatic adaptation of oxygen flows may reduce this frequency.

(III) that excessive oxygenation targets have no advantage. Our hypothesis is that maintaining a SpO2 of 90 to 94% is at least equivalent when compared to higher saturation objectives (SpO2 of 94 to 100%) with regard to the occurrence of complications in the patient in acute coronary syndrome . We will use two SpO2 targets with the FreeO2 system, 92 and 97%.

Hypoxemia is a common problem encountered during acute coronary syndrome. During acute coronary syndrome, the American College of Cardiology and the American Heart Association recommend oxygen delivery to patients with less than 90% oxygen saturation. Oxygen therapy in these patients for a duration of at least 6 hours , but also stipulates that it is reasonable to administer oxygen to all acute coronary syndrome patients during the first six hours Following the presentation. However, the studies underlying these guidelines are few and far between, most of them having been done more than forty years ago.

Hyperoxia also has well-established risks.

Our research hypotheses are:

(I) that current practices tend to use high oxygen flows resulting in high SpO2 levels during acute coronary syndrome.

(II) there is a high rate of desaturation in patients with acute coronary syndrome and an automatic adaptation of oxygen flows may reduce this frequency. This will be our primary endpoint and will be tested with the use of the automated oxygen delivery system.

(III) that excessive oxygenation targets have no advantage. Our hypothesis is that maintaining a SpO2 of 90 to 94% is at least equivalent when compared to higher saturation objectives (SpO2 of 94 to 100%) with regard to the occurrence of complications in the patient in acute coronary syndrome . We will use two SpO2 targets with the FreeO2 system, 92 and 97%.

Inclusion Criteria:

• Patients should have a proven diagnosis of acute high risk coronary syndrome as defined by the American Heart Association:
• myocardial infarction with or without ST segment elevation: Ischemic changes in the electrocardiogram and positive cardiac biomarkers.
• or Unstable angina: Typical or atypical cardiac symptoms, Ischemic electrocardiographic changes, Normal cardiac biomarkers.

Exclusion Criteria:

• inclusion in another study refusing co-enrollment
• chronic obstructive pulmonary disease with CO2 retention
• sleep apnea-hypopnea syndrome with CPAP
• traumatic brain injury
• pregnancy
• Age <18 years
• Mechanical invasive or non-invasive ventilation
• patient needing more than 5 lpm of oxygen to have SpO2 > 95%