This clinical trial will be carried out as a national multicenter observational cohort trial in Turkey. Our starting point is the need to triage postoperative patients daily due to the limited intensive care unit (ICU) bed capacity. Our hypothesis is that patients requiring emergency or unplanned ICU admission generally meet the ICU admission criteria. However, postoperative patients admitted to the ICU for planned reasons often do not meet the ICU admission criteria and can be monitored in a lower-level unit (Postoperative Care Unit - PACU) for close observation purposes.

The primary aim is to assess the efficient utilization of ICU beds. We try to compare the treatments provided during ICU follow-up, for planned and unplanned patients requiring ICU admission. Our secondary outcome is to identify criteria that can predict ICU indications based on patients' preoperative characteristics and evaluate the postoperative complications according to the Clavien-Dindo classification.

Our aim is to categorize patients admitted to the ICU into two groups: planned and unplanned/emergency cases and compare the necessity of ICU care between these two groups. The need for ICU treatment will be determined based on the criteria established in the following* study. The presence of any of these criteria will indicate the need for ICU admission, while the absence of these criteria may identify patients admitted to the ICU only for monitoring purposes (i.e., unnecessary ICU admissions).

Surgical cases involving patients over 18 years of age requiring postoperative intensive care will be included (including patients who were admitted urgently, or patients that is planned but not admitted to ICU after the surgery).

Cardiac surgery cases, outpatient cases, pediatric surgery cases, patients undergoing surgery while hospitalized in the ICU, patients undergoing only interventional procedures, and those who do not provide consent will be excluded from the study.

Inclusion Criteria:

• Age ≥ 18 years
• Major elective/emergency surgical procedures
• Planned, unplanned, emergent surgical procedures, planned but not admitted to the ICU after the operation.
• Patients who planned but not transferred to the ICU will also be followed/ included postoperatively
• Informed Consent
• Major surgeries will be targeted within the broad subgroup domains of gynecology, neurosurgery, thoracic, urology, orthopedics/trauma, and abdominal surgery.
• Unplanned but admitted to ICU after surgery in 48 hrs.

Exclusion Criteria:

• Day-case surgery
• Cardiac surgery
• Pediatric surgery
• Patients who were already staying in ICU and planned to be operated on
• Denial of informed consent
• All interventional procedures

The study population consists of patients requiring intensive care treatment in the postoperative period.

The study population comprises individuals who have undergone surgery and require intensive care, regardless of whether their admission to the ICU was planned or unplanned.