Timing of Complications in the First 24 Hours After Admission to a Postoperative (POSTICU-24)

Evaluation of the Temporal Distribution and Severity of Complications Within the First 24 Hours in Patients Admitted to the Postoperative Intensive Care Unit

The optimal duration and intensity of intensive care monitoring after surgery is largely determined by clinical experience rather than by objective, time-based evidence. This prospective observational cohort study aims to determine how frequently clinically significant complications occur in adult patients admitted to a postoperative intensive care unit (ICU), and - more specifically - when they occur during the first 24 hours after ICU admission. Patients will be followed under standard clinical care, with no additional intervention.

The time of ICU admission is defined as hour 0. Complications are recorded with their exact time of first onset, and cumulative incidence is calculated for the predefined windows 0-2, 2-6, 6-8, 8-12 and 12-24 hours. The study will assess whether complications cluster in the early postoperative period (first 6-8 hours) and what proportion of the total 24-hour complication burden this early window represents. A separate analysis will determine how often patients who remain complication-free during the first 6 hours subsequently develop a new, clinically significant complication. The findings are intended to inform evidence-based decisions about the required duration of close postoperative ICU monitoring

Study Overview

• Status: Recruiting
• Conditions: Postoperative Care

Detailed Description

Design and setting This is a single-centre, prospective, observational cohort study conducted in the postoperative (surgical) intensive care unit of the Department of Anesthesiology and Reanimation of a tertiary training and research hospital. Population Consecutive adult patients (>=18 years) admitted to the ICU for postoperative monitoring after elective or emergency surgery will be enrolled. No study-specific intervention is performed; all patients receive standard clinical care. All data are extracted from routinely collected clinical records: patient charts, anaesthesia records, ICU observation forms, hourly nursing charts, monitor recordings and laboratory results. Time definition The moment of ICU admission is defined as hour 0. All patients are followed from this reference point. Systematic assessments are performed at 0-2, 2-6, 6-8, 8-12 and 12-24 hours. In addition, hourly nursing and monitor records are used to determine the timing of each complication as precisely as possible (hour and, where available, minute level). For every complication, the time of first onset is recorded separately. Data collected Demographic and preoperative data (age, sex, height, weight, body mass index, ASA physical status, comorbidities, preoperative laboratory values, chronic medication); intraoperative data (surgical specialty and procedure type, elective vs emergency status, duration of surgery, anaesthetic technique, intraoperative hypotension or arrhythmia, fluid and blood product administration, vasopressor/inotrope requirement, extubation status); and postoperative ICU monitoring parameters recorded within each time window (heart rate, mean arterial pressure, vasopressor/inotrope use and dose changes, SpO2, respiratory rate, mode of oxygen therapy, mechanical ventilation status, reintubation, hourly urine output, serum creatinine, level of consciousness, sedation/agitation level, delirium assessment where applicable, arterial blood gas, haemoglobin/haematocrit, troponin and lactate where available). Complication assessment Complications are assessed against predefined objective criteria. Only events that are clinically significant and/or require intervention are recorded as complications. For each complication, the time of first onset, the diagnostic criterion applied, the requirement for clinical intervention and whether the event was recurrent are recorded separately.

Where a patient develops more than one complication, each is recorded as a separate event and the time of the first complication is additionally analysed. Predefined complication categories are: acute kidney injury, cardiac arrhythmia, respiratory complications, haemodynamic instability, neurological complications, bleeding and transfusion requirement, and infectious complications. Complication severity is graded using the Clavien-Dindo classification. Complication types, timing of onset and early-window complication rates are analysed separately for each group. 7. Study Design Study Type Observational Observational Study Model Cohort be calculated for the 0-6, 0-8, 8-12 and 12-24 hour windows. Early complication development (first 6-8 hours) will be defined as a binary variable and its capacity to represent the total complication burden will be analysed. Independent risk factors will be identified by logistic regression, with Cox regression where time-dependent effects require assessment. Results will be reported with odds ratios and 95% confidence intervals. Ethics The study will be conducted in accordance with the Declaration of Helsinki and the principles of Good Clinical Practice. All data will be anonymised. The study involves no additional intervention and poses no risk to participants.

• Study Type: Observational
• Enrollment (Estimated): 480

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Istanbul, Turkey (Türkiye), 34303
    • Recruiting
    • Health Science University İstanbul Kanuni Sultan Süleyman Education and Training Hospital
    • Contact: Engin İhsan Turan, MD; Phone Number: +905382431114; Email: enginihsan@hotmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

Adult patients admitted to the postoperative (surgical) intensive care unit of a tertiary training and research hospital for postoperative monitoring following elective or emergency surgery.

Description

Inclusion Criteria:

• Age 18 years or older
• Underwent elective or emergency surgery
• Admitted to the intensive care unit for postoperative monitoring after surgery
• Monitored in the ICU for at least 24 hours, or sufficient clinical data available for the first 24 hours of monitoring
• Time of ICU admission and course of monitoring reliably documented

Exclusion Criteria:

• Age under 18 years
• Pre-existing active organ failure before surgery (for example preoperative acute kidney injury, sustained arrhythmia, requirement for invasive mechanical ventilation)
• Admitted to the ICU because of continuing critical illness rather than for monitoring of new postoperative complications
• Already an ICU inpatient before surgery and readmitted to the ICU postoperatively
• Time of complication onset cannot be reliably determined, or records are inadequate
• Incomplete data for the first 24 hours of ICU monitoring
• Terminal illness managed with a palliative approach

Study Plan

How is the study designed?

Design Details

• Observational Models: COHORT
• Time Perspectives: PROSPECTIVE

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Postoperative ICU cohort; Adult patients admitted to the postoperative (surgical) intensive care unit for routine postoperative monitoring following elective or emergency surgery. No study intervention is applied; patients are observed under standard clinical care for the first 24 hours after ICU admission. Prespecified subgroup analyses are performed by surgical specialty.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cumulative incidence of clinically significant postoperative complications by time	Number and percentage of patients developing at least one predefined, clinically significant postoperative complication within each time window after ICU admission (0-2, 2-6, 6-8, 8-12 and 12-24 hours). Complication categories are acute kidney injury,arrhythmia, respiratory complications, haemodynamic instability, neurological complications, bleeding requiring transfusion, and infectious complications. Only events meeting predefined objective diagnostic criteria and judged clinically significant and/or requiring intervention are counted.	First 24 hours after ICU admission

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to first complication	Time in hours from ICU admission to onset of the first clinically significant complication	24 hour
New complications after an event-free first 6 hours	Proportion of patients free of any clinically significant complication during the first 6 hours who subsequently develop a new clinically significant complication.	6 to 24 hours
Complication severity	Severity of each recorded complication graded by the Clavien-Dindo classification	24 hours
Complication type and timing by surgical specialty	Distribution of complication categories and time of first onset, analysed separately for each surgical specialty subgroup	24 hours
Independent risk factors for complication development	Patient and perioperative variables independently associated with complication development	24 hours

Collaborators and Investigators

• Sponsor: Kanuni Sultan Suleyman Training and Research Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): September 9, 2026
• Primary Completion (Estimated): September 9, 2027
• Study Completion (Estimated): September 10, 2027

Study Registration Dates

• First Submitted: September 28, 2026
• First Submitted That Met QC Criteria: September 28, 2026
• First Posted (Actual): October 2, 2026

Study Record Updates

• Last Update Posted (Actual): October 2, 2026
• Last Update Submitted That Met QC Criteria: September 28, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: complications

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No