Fasting in critical illness: the role of ketonuria - a retrospective observational study.

Background: Metabolic acidosis is a frequent finding in patients admitted to the intensive care unit (ICU). It can be caused by prolonged fasting due to surgical procedures or by medical conditions that lead to starvation ketoacidosis (SKA). Early recognition and treatment of SKA could prevent several life-threatening complications, improving survival and reducing the ICU length of stay.

Methods: We retrospectively screened all medical records of patients admitted to the ICU (Maggiore Hospital, Bologna, North Italy) from May 2022 to April 2023. We included patients aged 18 years or older who presented ketonuria detected in the urine sample.

Results: We analyzed 190 patients with ketonuria at ICU admission. Postsurgical patients showed lower levels of albumin and a higher rate of shock compared to medical patients. Ketonuric patients with shock had a lower body mass index (BMI) compared to patients without shock (24 versus 26 kg/m2, respectively). There were no differences within groups regarding mortality and ICU readmission rate. Medical patients had a significantly higher ICU length of stay.

Conclusions: This retrospective observational descriptive study showed that patients with ketonuria, hypoalbuminemia, and low BMI at ICU admission have high risk of hemodynamic instability and shock. Surgical patients compared to medical patients are exposed to a catabolic trigger that could worsen a state of malnutrition and induce anabolic resistance; elective and urgent surgical patients did not differ in terms of risk of shock and mortality, probably due to the activation of this catabolic pathway. Early recognition and treatment of starvation ketoacidosis and perioperative nutritional optimization could reduce incidence of hemodynamic and metabolic complications.