Original Investigation 

Caring for the Critically Ill Patient

Fluid Therapy in Mechanically Ventilated Critically Ill Adult Patients

Siebe G. Blok, Harm-Jan de Grooth, Luigi Pisani, et al

JAMA Published Online: October 14, 2026

doi: 10.1001/jama.2026.21291

Key Points

Question  How is fluid therapy administered in mechanically ventilated critically ill patients?

Findings  In this cohort study of 2454 mechanically ventilated adults in 41 countries, median daily fluid input was 3.0 L on the first day of intubation with neutral fluid balance after day 3. Maintenance accounted for 32% and creep fluid (to deliver medications and maintain catheter patency) accounted for 31%; resuscitation fluid accounted for 16%, and substantial variation in fluid therapy across sites persisted after case-mix adjustment.

Meaning  These findings highlight opportunities for harmonizing fluid therapy across centers and extend fluid stewardship beyond resuscitation to maintenance and creep fluids.

Abstract

Importance  Fluid therapy is ubiquitous in the intensive care unit (ICU) but carries risks, especially in mechanically ventilated patients. Contemporary global practice across dose, indication, and type is unknown.

Objective  To characterize ICU fluid practices in mechanically ventilated adults.

Design, Setting, and Participants  International prospective observational cohort study between April 2024 and July 2025, across 206 ICUs in 41 countries on 6 continents. Consecutive adult patients receiving invasive mechanical ventilation within 3 days of ICU admission and ventilated 24 hours or more. Exclusion criteria were age younger than 16 years and transfer under mechanical ventilation from another ICU.

Exposures  Fluid volume, indication, and type after intubation.

Main Outcomes and Measures  Key measures included (1) total infused volume and daily fluid balance over 7 days after intubation; (2) the indication for fluid therapy over the first 3 days after intubation; (3) the proportion of total administered fluid volume attributable to each fluid type over the first 3 days after intubation.

Results  Among 2454 patients analyzed (median age, 63 years [IQR, 49-73 years]; 63.6% [1560] male), median daily fluid input peaked on day 1 at 3.0 L (IQR, 2.2-4.0 L) and declined to 2.6 L (IQR, 1.8-3.5 L) through day 6. Daily fluid balance (median, 0.9 L; IQR, 0.1-1.9 L on day 1) decreased to less than 0.3 L (IQR, −0.5 to 1.2 L) by day 3 and remained near-neutral through day 6. Maintenance and replacement fluids (to meet daily requirements and to correct ongoing losses; 31.9%) and creep fluids (to deliver medications and maintain catheter patency; 30.9%) were the primary indications, whereas resuscitation (to restore circulating blood volume; 16.0%) accounted for a smaller proportion. Isotonic balanced crystalloids (48.9%) and isotonic saline (0.9% sodium chloride) (27.0%) were common; colloids were rare (1.3%). Substantial between-site variation persisted after adjustment for case-mix.

Conclusions and Relevance  In this prospective international cohort study, fluid therapy varied widely among mechanically ventilated critically ill patients, with maintenance and creep fluids—rather than resuscitation fluids—accounting for most total volume.