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Ketosis, Immune Function and Metabolic Adaptation in Response to Short-term Fasting in Critical Illness (KETO-FAST)

28 agosto 2026 aggiornato da: Martin Sundstrom Rehal, Karolinska University Hospital

KETOsis, Immune Function and Metabolic Adaptation in Response to Short-Term Fasting in Critical Illness (KETO-FAST): A Translational Substudy of the FAST-ICU Cluster-randomized Cross-over Trial.

KETO-FAST is a pre-planned translational substudy of the FAST-ICU cluster-randomized cross-over trial. The substudy will characterize ketone body production and associated metabolic, autophagy-related, and immune cellular responses during the first 72 hours after intensive care unit admission in critically ill patients exposed to delayed nutrition compared with patients receiving standard care.

Patients enrolled in FAST-ICU at designated participating centers will undergo serial blood sampling during the first 72 hours after ICU admission. Plasma ketone body concentrations, targeted metabolomics, serum-induced cellular responses in vitro, leukocyte autophagy markers, and immune cell phenotypes and functional markers will be assessed. In addition, 10 healthy volunteers will perform a 72-hour fast with blood sampling to provide reference values from non-critically ill subjects.

Panoramica dello studio

Stato

Non ancora reclutamento

Condizioni

Intervento / Trattamento

Descrizione dettagliata

Early nutrition during critical illness remains controversial. Large randomized trials in intensive care unit patients have found no clear benefit and possible harm from full early feeding, while current guidelines recommend early hypocaloric nutrition. However, high-quality evidence comparing early hypocaloric nutrition with complete withholding of nutrition during the first days of critical illness is limited.

In healthy humans, short-term starvation induces ketone body production through fatty acid oxidation. Ketone bodies such as β-hydroxybutyrate and acetoacetate are energy substrates for organs including the heart and brain and may also act as signaling molecules involved in autophagy, mitochondrial metabolism, and immune function. In critical illness, however, the normal fasting response may be altered by stress metabolism, inflammation, insulin administration, corticosteroids, and organ dysfunction. The extent to which critically ill patients develop clinically relevant ketosis during short-term fasting remains uncertain.

The parent FAST-ICU trial is a cluster-randomized cross-over trial comparing two ICU nutrition strategies during the first 72 hours after ICU admission: delayed nutrition with no enteral or parenteral nutrition and no glucose-containing maintenance fluids, versus standard care including early enteral nutrition and maintenance glucose according to local practice. KETO-FAST uses this randomized exposure to study the biological response to short-term fasting in critically ill patients.

The primary objective of KETO-FAST is to compare plasma ketone body concentrations during the first 72 hours after ICU admission between patients exposed to delayed nutrition and patients receiving standard care. Secondary and exploratory objectives are to characterize associated changes in targeted metabolic pathways, serum-mediated cellular responses, leukocyte autophagy markers, and immune cell phenotypes and functional markers.

Tipo di studio

Interventistico

Iscrizione (Stimato)

200

Fase

  • Non applicabile

Contatti e Sedi

Questa sezione fornisce i recapiti di coloro che conducono lo studio e informazioni su dove viene condotto lo studio.

Contatto studio

Luoghi di studio

Criteri di partecipazione

I ricercatori cercano persone che corrispondano a una certa descrizione, chiamata criteri di ammissibilità. Alcuni esempi di questi criteri sono le condizioni generali di salute di una persona o trattamenti precedenti.

Criteri di ammissibilità

Età idonea allo studio

  • Adulto
  • Adulto più anziano

Accetta volontari sani

Sì

Descrizione

Inclusion Criteria:

  1. Adult (≥18 years).
  2. ICU admission (index admission to the participating ICU).

Exclusion Criteria:

  1. The patient requires intravenous glucose infusion, enteral nutrition or parenteral nutrition according to the attending clinician's assessment,
  2. Acute or acute-on-chronic liver failure
  3. Moderate hypernatremia ( >150 mmol/L)
  4. Diabetic ketoacidosis or hyperosmolar hyperglycemic state at admission,
  5. Pregnancy,
  6. Exclusive end-of-life care (no other treatment goal than comfort care for end of life),
  7. Organ donor,
  8. Prior enrolment in this trial during the same hospitalisation,
  9. Patients with a metabolic disease requiring specific diet and patients with clinical need for a ketogenic diet.
  10. Patients already enrolled in other interventional studies on nutrition, intravenous fluids, phosphate supplementation or hormonal therapies that influence glucose homeostasis.
  11. Inclusion not possible due to site-specific regulatory issues regarding the ethical approval or informed consent procedure.

Piano di studio

Questa sezione fornisce i dettagli del piano di studio, compreso il modo in cui lo studio è progettato e ciò che lo studio sta misurando.

Come è strutturato lo studio?

Dettagli di progettazione

  • Scopo principale: Trattamento
  • Assegnazione: Randomizzato
  • Modello interventistico: Assegnazione incrociata
  • Mascheramento: Nessuno (etichetta aperta)

Armi e interventi

Gruppo di partecipanti / Arm
Intervento / Trattamento
Sperimentale: Intervention
Intensive care unit patients with policy allocation to delayed medical nutrition therapy in main study: no enteral nutrition, parenteral nutrition or maintenance glucose solutions for first 72 hours.

Intervention Policy (A): Withhold nutrition and glucose solutions (First 72 h)

  • No enteral nutrition (EN) and no parenteral nutrition (PN) for the first 72 hours from ICU admission time (t=0).
  • No glucose-containing maintenance IV solutions during the first 72 hours. Balanced crystalloids or normal saline permitted per clinical need.
  • 5% glucose solution permitted as vehicle for IV medications as necessary (according to local standard), or as treatment for hypernatremia
  • Oral intake permitted ad lib if the patient is awake, willing and able to eat safely.
  • Micronutrients: daily vitamins and trace elements are allowed per local practice.
  • Protein supplements are not allowed unless part of the standard oral diet.
  • Arterial or venous blood glucose measurement every 4h.
  • Rescue glucose will be administered according to local protocol.
  • After 72 hours, feeding transitions to usual care at clinician discretion (including EN/PN initiation and caloric/protein targets).
Comparatore attivo: Control
Intensive care unit patients with policy allocation to standard care in main study: nutritional management according to regular unit protocols.

Control Policy (B): Standard of Care

  • Initiation and advancement of EN/PN and use of glucose-containing maintenance fluids per local practice from admission.
  • Arterial or venous blood glucose measurement every 4h.
  • Insulin and glycaemic control per local protocols.
Comparatore attivo: Healthy reference controls
Healthy subjects undergoing 72 hour fast with same blood sampling procedure as in ICU.
72-hour fasting period with water and non-caloric beverages.

Cosa sta misurando lo studio?

Misure di risultato primarie

Misura del risultato
Misura Descrizione
Lasso di tempo
Between-group differences over time in plasma β-hydroxybutyrate and acetoacetate concentrations during the first 72 hours after ICU admission
Lasso di tempo: From ICU admission and up to 72 hours after ICU admission, using serial daily blood samples
Plasma β-hydroxybutyrate and acetoacetate concentrations will be measured in mmol/L in serial blood samples collected from ICU admission through 72 hours after admission. Cumulative concentrations of ketone bodies will be compared between the delayed-nutrition and standard-care groups over the measurement period. Results will be reported as between-group effect estimates over time, with 95% confidence intervals.
From ICU admission and up to 72 hours after ICU admission, using serial daily blood samples

Misure di risultato secondarie

Misura del risultato
Misura Descrizione
Lasso di tempo
Between-group difference in serum-induced autophagy flux in cultured cells
Lasso di tempo: Single serum sample collected on ICU day 3 or 4, depending on the time of ICU admission
Cultured cells will be incubated with serum collected from substudy participants. Autophagy flux will be quantified using prespecified cellular autophagy markers under paired conditions with and without pharmacological inhibition of lysosomal degradation. The resulting normalized autophagy-flux measure will be compared between the delayed-nutrition and standard-care groups and reported as a between-group effect estimate with a 95% confidence interval.
Single serum sample collected on ICU day 3 or 4, depending on the time of ICU admission
Between-group difference in normalized relative abundance of autophagy-related proteins in peripheral blood leukocytes assessed by Western blotting
Lasso di tempo: Single final substudy sample collected on ICU day 3 or 4, depending on the time of ICU admission
The relative abundance of prespecified autophagy-related proteins will be quantified in isolated peripheral blood leukocytes by Western blot densitometry and normalized to an appropriate loading control. For each protein marker, and for derived protein ratios where applicable, normalized values will be compared between the randomized groups and reported as a between-group effect estimate with a 95% confidence interval.
Single final substudy sample collected on ICU day 3 or 4, depending on the time of ICU admission
Between-group differences in frequencies of major peripheral blood immune-cell subsets assessed by multiparameter flow cytometry
Lasso di tempo: Single final substudy sample collected on ICU day 3 or 4, depending on the time of ICU admission
Multiparameter flow cytometry will be used to identify and quantify prespecified major immune-cell populations and phenotypic subsets relevant to critical illness and nutrient deprivation. Each subset will primarily be expressed as a percentage of its relevant parent cell population. Subset frequencies will be compared between the delayed-nutrition and standard-care groups and reported as between-group effect estimates with 95% confidence intervals.
Single final substudy sample collected on ICU day 3 or 4, depending on the time of ICU admission
Between-group differences in immune-cell phenotypes and marker expression assessed by multiparameter flow cytometry
Lasso di tempo: Single final substudy sample collected on ICU day 3 or 4, depending on the time of ICU admission
Prespecified peripheral blood immune-cell populations will be characterized by multiparameter flow cytometry. Outcomes will include the frequency of cell populations expressing markers related to immune activation, exhaustion or immune-checkpoint signalling, cellular metabolic state, and functional capacity, together with marker-expression intensity where applicable. Results for each prespecified cell population and marker will be compared between the delayed-nutrition and standard-care groups and reported as between-group effect estimates with 95% confidence intervals.
Single final substudy sample collected on ICU day 3 or 4, depending on the time of ICU admission
Between-group difference in normalized expression of prespecified autophagy-related genes in peripheral whole blood on ICU day 3 or 4, assessed by RNA sequencing
Lasso di tempo: Single blood sample collected on ICU day 3 or 4, depending on the time of ICU admission
RNA will be extracted from peripheral whole blood collected in EDTA tubes on ICU day 3 or 4. Expression of prespecified autophagy-related genes will be quantified using RNA sequencing and compared between the randomized groups. For each gene, the treatment effect will be reported as the between-group log2 fold change with a 95% confidence interval and a false-discovery-rate-adjusted P value.
Single blood sample collected on ICU day 3 or 4, depending on the time of ICU admission
Between-group differences in plasma concentrations of prespecified metabolites and pathway-level metabolomic measures during the first 72 hours after ICU admission
Lasso di tempo: From ICU admission and up to 72 hours after ICU admission, using serial daily blood samples
Targeted metabolomic analysis will quantify prespecified plasma metabolites related to metabolic pathways relevant to fasting and critical illness, including ketogenesis, fatty acid metabolism, amino acid metabolism, glycolysis, and the tricarboxylic acid cycle. Individual metabolite concentrations and predefined pathway-level summary measures, where applicable, will be compared between the delayed-nutrition and standard-care groups across the first 72 hours after ICU admission. Results will be reported as between-group effect estimates with 95% confidence intervals.
From ICU admission and up to 72 hours after ICU admission, using serial daily blood samples

Altre misure di risultato

Misura del risultato
Misura Descrizione
Lasso di tempo
Between-group differences in point-of-care whole-blood β-hydroxybutyrate concentration during the first 72 hours after ICU admission
Lasso di tempo: From ICU admission and up to 72 hours after ICU admission, using serial daily blood samples
Whole-blood β-hydroxybutyrate concentration will be measured in mmol/L using a point-of-care ketone analyzer at participating sites where this measurement is available. Measurements obtained from ICU admission through 72 hours will be compared between the delayed-nutrition and standard-care groups. Results will be reported for individual sampling time points and as an overall between-group effect across the measurement period, with 95% confidence intervals.
From ICU admission and up to 72 hours after ICU admission, using serial daily blood samples

Collaboratori e investigatori

Qui è dove troverai le persone e le organizzazioni coinvolte in questo studio.

Sponsor

Collaboratori

Investigatori

  • Cattedra di studio: Olav Rooyackers, PhD, Karolinska University Hospital/Karolinska Institute
  • Investigatore principale: Martin Sundström Rehal, MD PhD, Karolinska University Hospital/Karolinska Institutet

Studiare le date dei record

Queste date tengono traccia dell'avanzamento della registrazione dello studio e dell'invio dei risultati di sintesi a ClinicalTrials.gov. I record degli studi e i risultati riportati vengono esaminati dalla National Library of Medicine (NLM) per assicurarsi che soddisfino specifici standard di controllo della qualità prima di essere pubblicati sul sito Web pubblico.

Studia le date principali

Inizio studio (Stimato)

31 agosto 2026

Completamento primario (Stimato)

31 luglio 2027

Completamento dello studio (Stimato)

31 luglio 2027

Date di iscrizione allo studio

Primo inviato

13 luglio 2026

Primo inviato che soddisfa i criteri di controllo qualità

29 luglio 2026

Primo Inserito (Effettivo)

31 luglio 2026

Aggiornamenti dei record di studio

Ultimo aggiornamento pubblicato (Effettivo)

1 settembre 2026

Ultimo aggiornamento inviato che soddisfa i criteri QC

28 agosto 2026

Ultimo verificato

1 agosto 2026

Maggiori informazioni

Termini relativi a questo studio

Altri numeri di identificazione dello studio

  • K 2026-5194
  • ISRCTN16339579 (Identificatore di registro: ISRCTN)

Piano per i dati dei singoli partecipanti (IPD)

Hai intenzione di condividere i dati dei singoli partecipanti (IPD)?

SÌ

Descrizione del piano IPD

De-identified individual participant data may be made available after publication of the main substudy results upon reasonable request and according to applicable ethical approvals, data protection regulations, biobanking regulations, and material transfer agreements. Omics data sharing will be governed by participant consent, ethical approval, and applicable data protection requirements.

Informazioni su farmaci e dispositivi, documenti di studio

Studia un prodotto farmaceutico regolamentato dalla FDA degli Stati Uniti

No

Studia un dispositivo regolamentato dalla FDA degli Stati Uniti

No

Queste informazioni sono state recuperate direttamente dal sito web clinicaltrials.gov senza alcuna modifica. In caso di richieste di modifica, rimozione o aggiornamento dei dettagli dello studio, contattare register@clinicaltrials.gov. Non appena verrà implementata una modifica su clinicaltrials.gov, questa verrà aggiornata automaticamente anche sul nostro sito web .