This study compares two different methods of helping patients breathe by placing a tube in their airway (intubation) in an emergency setting. These methods are called Rapid Sequence Intubation (RSI) and Delayed Sequence Intubation (DSI).

The study focuses on adult patients who are still breathing on their own but need a breathing tube for medical reasons not related to an injury (non-trauma).

The main goal of the research is to compare:

• Oxygen levels before and after the procedure.
• The patient's vital signs (such as heart rate and blood pressure).
• The number of attempts needed to successfully place the tube and the time the procedure takes.
• Blood gas results and any complications that occur during or shortly after the procedure.
• Early survival (mortality) rates.

While there are previous studies on trauma patients or small observational reports, there is currently no large-scale, multicenter randomized controlled trial that includes all non-trauma adult patients.

What makes this study unique? Confirmation of Tube Placement: Researchers will use a specific measurement called end-tidal CO2 (etCO2) to confirm the tube is in the right place, a method not used in similar previous studies.

Assessing Difficulty: This study will use the Cormack-Lehane classification system to measure how difficult the intubation was for each patient.

Standardization: For the first time, breathing machine (ventilator) settings will be standardized for all patients in this type of study.

Real-World Practice: By involving all emergency department physicians as practitioners, the study aims to show how these methods work across a wide range of medical teams.

Inclusion Criteria:

1. Aged 18 years or older

2. Presence of spontaneous breathing.

3. No prediction of a difficult airway prior to intubation.

4. Requirement for advanced airway management.

5. Not in cardiac arrest.

6. Decided to intubate due to non-traumatic etiologies.

7. Planned intubation using ketamine for sedation and rocuronium for paralysis.

8. Decision to intubate due to one of the following clinical conditions:

   1. Acute Respiratory Failure: Patients with hypoxic or hypercapnic respiratory failure where adequate oxygenation cannot be achieved despite non-invasive ventilation.
   2. Inability to Protect the Airway: Altered level of consciousness or increased risk of pulmonary aspiration due to conditions such as upper gastrointestinal bleeding, ileus, volvulus, gastric outlet obstruction, hypersalivation, or hyperemesis.
   3. Shock States: Patients in any state of shock (hypovolemic, distributive, cardiogenic, obstructive) exhibiting severe altered mental status or declining respiratory status.
   4. Neuroprotection: Need to terminate ongoing seizures resistant to medical therapy (status epilepticus), or situations requiring strict control of arterial carbon dioxide (PaCO₂) levels to manage increased intracranial pressure (ICP) in non-traumatic conditions (such as intracranial hemorrhage or severe encephalopathy).

9. Obtaining informed consent from the patient or their legally authorized representative.

Exclusion Criteria:

1. Aged under 18 years.
2. Pregnancy.
3. Refusal to provide informed consent.
4. Cardiac arrest prior to intubation.
5. Anticipated difficult airway.
6. Intubation required due to traumatic etiologies.
7. Missing or incomplete patient data.
8. Patients assigned to the DSI protocol but for whom the decision to intubate was rescinded due to clinical improvement during the preoxygenation phase.
9. Use of a sedative agent other than ketamine for the RSI protocol.
10. Intubations performed by practitioners who have not received study-specific training on DSI and RSI protocols.
11. Duplicate enrollment due to recurrent presentations during the study period.

After publication and upon reasonable request

Data will be available beginning 6 months and ending 36 months after article publication.

Requests for data should be directed to the principal investigator. To gain access, data requestors will need to sign a data access agreement.