Postoperative delirium is an acute syndrome of mental deterioration characterized by acute onset and fluctuating course during the day. Very frequent delirium is a presage of other serious comorbidities i.e.: sepsis, acute kidney injury, circulatory and/or respiratory failure. A detailed knowledge of symptoms and early diagnose of delirium increase the chances of early therapy. To what extent the occurrence of postoperative delirium influences hospital therapy in the Cardiac Surgical Postoperative ICU in University Clinical Centre in Gdańsk is unknown so far.

Study type: prospective, observational cohort study. Facility: tertiary, university hospital Methods: Patients will undergo routine, continuous observation for symptoms of delirium by a trained nursing staff. Occurrence of delirium, Delirium Observation Screening Scale (DOSS) grading, and therapy will by annotated on case record forms (CRFs) every 12 hours. Additionally, collected will be known risk factors of delirium: schedule type, age, arterial hypertension, atrial fibrillation, body mass index (BMI), angiotensin converting enzyme (ACE) inhibitors / angiotensin receptor blockers (ARBs) therapy, hearing loss, dementia, peripheral artery disease, myocardial infarction, depression, diabetes, corona virus disease 2019 (COVID19) infection and/or vaccination; and outcome data: hospital-LOS, prolonged sedation, antipsychotic therapy, surgical reintervention, hours on mechanical ventilation (HOV), number of tracheal intubations, length of consciousness disorders, blood product transfusions, cardiopulmonary resuscitation (CPR), renal replacement therapy (RRT), mechanical circulatory support (MCS), duration of catecholamine support, ICU readmissions, new antibiotic therapies, 30-day mortality.

Statistical methods: Delirium morbidity and risk will be calculated from two-by-two table. Associations between delirium and secondary outcome measures will be evaluated by simple and logistic regression with use of ANOVA test for continuous variables with homogeneous distribution, or Kruskal-Wallis test for continuous variables with non-homogeneous distribution, or categorical variables. Significant will be considered results with p<0.05.

A period of one year was assumed sufficient to draw conclusions on the primary endpoints of the study.

Inclusion Criteria:

• Adult patients (>18 y.a.), undergoing cardiac surgery, who will sign an informed consent to participate in the study.

Exclusion Criteria:

• Deny to sign or absence of an informed consent.

Gender will be reported as declared by the subjects.

All adult patients undergoing elective/emergency cardiac surgery will be considered eligible.

Anonymized patients data are planned to be uploaded into a public data repository (ZENODO.com) after data completion.