Intensive care units are inevitable for high risk surgery and/or high risk patients i.e. patients with severe preconditions. However, usually the capacity of these units is limited such that at times elective surgery has to be postponed if there is no ICU capacity.

The aim of this study is to investigate potential influence/risk factors important for ICU admission in a university hospital in Germany and develop a risk score. In a second phase the risk score for ICU admission will be validated.

It is one of the core duties of anesthesiologists in our hospital to identify patients with high risk for a post-surgery ICU stay upon hospital admission. We do know that there are two types of factors influencing the possibility of an ICU admission: The patient centered risk e.g. severe preconditions and the surgery centered risk depending on the type of surgery with sometimes high possibility for perioperative complications i.e. bleeding, hemodynamic instability, pulmonary complications etc. However, we do not know the effect size of these factors and, equally important, how they are correlated with one another.

The aim of this study is to model the risk of an ICU stay by patient centered and surgery centered influence factors. If a good model is obtained, this can be utilized for allocating ICU capacities in an objective fashion. The study consists of two phases. In the first phase model selection is performed. In the second phase the developed model will be validated on independent data. Data will be gathered by a data collection sheet completed by the responsible anesthesiologists in all elective and emergency surgery during a specific period of time.

Inclusion Criteria:

• All patients ≥ 18 years receiving surgery in the time frame of data collection with ASA classification status I-IV

Exclusion Criteria:

• Patients < 18 years
• ASA classification status > IV

All patients meeting inclusion criteria and receiving elective or emergency surgery