The final approach adopted in Advanced Cardiac Life Support (ACLS) guidelines as defined by the American Heart Association (AHA) and the European Resuscitation Council (ERC) is to minimize the time between chest compressions in cardiopulmonary resuscitation (CPR). Pulse and rhythm checks are recommended between chest compressions and it is stated that this period should not exceed 10 seconds.

All guidelines also state that in cases of low cardiac output or low blood pressure, even if electrocardiographic (ECG) rhythms can be obtained, pulse checks may still fail and an arterial pulse may not be felt during chest compressions. This difficulty in sensing the arterial pulse causes delays in the decision of cardiac arrest in the patient. For this reason, there are cases of cardiac arrest in which the initiation of CPR is delayed or not started at all.

The most common method for checking the pulse is manual palpation. However, since it is an operator-dependent method, it is affected by the experience of the healthcare personnel, the vital values of the patient, and anatomical differences. Therefore, more objective criteria are required to detect a pulse. A clinical study of the reliability of pulse checks showed that most healthcare professionals are unable to detect the presence or absence of a pulse. Another study showed that pulse alone is not sufficient to initiate CPR, and 50% of decisions to initiate CPR based on heart rate are incorrect. Therefore, more objective criteria have been sought to detect the presence of a pulse. For this purpose, evaluations were made regarding the presence of end-tidal carbon dioxide, cardiac echo, and organized rhythm.

Inclusion Criteria:

• All adult patients (over 18 years of age) with in-hospital or out-of-hospital cardiac arrest

Exclusion Criteria:

• Patients with traumatic arrest
• Conditions affecting carotid pulse palpation and/or USG application (patients with a history of carotid stenosis or dissection, patients undergoing neck surgery, patients with neck abscess hematoma)
• Pregnant arrest patients

patients over 18 years old

All data and statistical analyzes will be shared with academics and official institutions requesting the patient's names, provided that they remain confidential, after the permission of the institution.