Incidence and Associated Risk Factors of ARC in the Trauma Critically Ill Older Than 50 Years Old

This single-center prospective cohort study conducted at the adult trauma ICU of the Montreal General Hospital (MGH) affiliated with the McGill University Health Centre (MUHC) aims to determine the incidence and associated risk factors of augmented renal clearance (ARC) in critically ill trauma patients of 50 years old and above.

Patients aged 50 years or older admitted to the ICU for traumatic brain injury (TBI) and/or polytrauma between January 2021 and October 2021 will be screened for study enrollment according to inclusion and exclusion criteria.

Research hypothesis :

* Critically ill trauma patients aged 50 years or older admitted to the ICU present an augmented renal clearance;
* A set of factors could predict, to a certain extent, the risk of developing ARC in critically ill trauma patients aged 50 years or older admitted to the ICU.

ARC will be assessed for every patient based on daily 8-hour urine collections started within the first 24 hours of ICU admission and daily serum creatinine concentrations. The first seven days will consist of daily urinary collection while only biweekly samples (days 10 and 14) will be collected for the second week. Since ARC is a time-sensitive event, the use of a deferred consent will allow for urine collection to begin as soon as possible after admission. All other data required for the study (demographic and other clinically relevant data) will be collected retrospectively once consent from surrogate or patient has been obtained. Data will be collected from study enrollment up until one of the following events : 1) Day 14 of ICU stay ; 2) ICU discharge; 3) AKI onset; 4) institution of RRT; 5) Removal of urinary catheter; 6) Withdrawal of informed consent; 7) Death; whichever occurs first.

Data regarding demographic variables including age, gender, anthropometric measurements, admission diagnosis, nature of injuries, comorbidities, and length of stay (LOS) will be obtained through the patient's medical records as well as the clinical information system. Data concerning ventilation and 24-hour fluid balance will be obtained through nursing records. Information regarding drug therapy (e.g., vasopressor and antibiotic use) will be obtained through the MUHC software. The Injury Severity Score (ISS) score will be compiled from the local Trauma Registry, while the Sequential Organ Failure Assessment (SOFA) score will be calculated directly.

Eligibility Criteria:
Inclusion Criteria:

* Admission to the ICU for isolated traumatic brain injury (TBI), polytrauma without TBI or combined polytrauma and TBI
* Expected ICU length of stay of more than 24 hours
* Age of ≥ 50 years old at the time of admission
* Serum creatinine ≤ 120 μmol/L at the time of admission
* Presence of an indwelling urinary catheter
* Consent is obtained from the patient or its surrogate decision-maker within 7 days of ICU admission

Exclusion Criteria:

* History of renal replacement therapy (RRT) (intermittent dialysis or peritoneal dialysis), nephrectomy or renal transplant
* Patient developing acute kidney injury (AKI)
* ICU physician considered patient unsuitable for enrollment due to poor prognosis
* Burn-related trauma
* Patient is admitted \> 48 hours post-traumatic event