Annals of Intensive Care 16 (2026) 100074
Contents lists available at ScienceDirect
Annals of Intensive Care
journal homepage: www.elsevier.com/locate/aicoj
Review
Unnecessary fluid therapy in patients with shock: Five classic fluid pitfalls
and five ways to do it better
Martin Vanden Eedea, Niels Van Regenmortelb,c,*
a
Ziekenhuis aan de Stroom Campus Middelheim, Department of Emergency Medicine, Lindendreef 1, 2020 Antwerpen, Belgium
b
Ziekenhuis aan de Stroom Campus Cadix, Department of Intensive Care Medicine, Kempenstraat 100, 2030 Antwerp, Belgium
c
Antwerp University Hospital, Department of Intensive Care Medicine, Drie Eikenstraat 655, 2650 Edegem, Belgium
ARTICLE INFO ABSTRACT
Keywords: Intravenous fluid therapy remains a cornerstone of shock management, yet is frequently misapplied.
Shock Unnecessary administration can lead to avoidable harm, including fluid accumulation, electrolyte
Fluid therapy disturbances, and delayed recovery. Despite good intentions, clinicians often fall into predictable patterns
Fluid overload that drive overinfusion. Recognizing and correcting these habits is an important step toward safer and more
Maintenance fluids
effective fluid management, which may contribute to better patient outcomes.
Resuscitation fluids
Sepsis
This narrative review highlights five recurring pitfalls in fluid management: confusion between
Pathophysiology resuscitation, maintenance, and replacement indications; failure to account for hidden fluid sources;
Volume status underestimation of the impact of sodium burdens; reflexive fluid administration in response to misinterpreted
Fluid stewardship markers such as hyperlactatemia, low central venous pressure or reduced urine output; and finally, a narrow
focus on fluid responsiveness without consideration of fluid tolerance.
To address these challenges, we propose a pragmatic, physiology-based approach to fluid stewardship. Key
strategies include adopting a phase-based model for fluid therapy, minimizing unnecessary sodium and
chloride exposure, interpreting fluid balance data with caution, initiating early vasopressor support when
appropriate, and employing structured de-resuscitation (and preventive) strategies rather than relying solely
on loop diuretics.
Thoughtful, physiology-driven fluid therapy requires more than reflexes, fixed volumes and flowcharts, it
demands context-sensitive, physiology-informed decision-making. By recognizing common mistakes and
adopting simple yet powerful principles, clinicians can shift from automatic to analytic and from flood to
finesse.
Background Historically, early goal-directed therapy was considered standard
of care, guided by protocols aiming to optimize arterial oxygen
Intravenous fluid therapy is often initiated with the best intentions. delivery. In practice, this often translated into rapid fluid administra-
However, when resuscitation fluids are administered without clear tion and a focus on urine output as surrogate indicators of treatment
physiological targets, or when maintenance fluids are misused in the success. A continuous stream of evidence in recent years has shown
context of shock, these good intentions can harm the patient. that various aspects of fluid therapy—such as fluid type, sodium
content, dosing strategies and guiding parameters such as fluid
responsiveness—can influence outcomes and that inappropriate or
Abbreviations: AKI, acute kidney injury; CVP, central venous pressure; DPB,
excessive fluid administration may be harmful in ICU patients
diastolic blood pressure; EVLW, extravascular lung water; FR, fluid
responsiveness; FT, fluid tolerance; GEDV, global end diastolic volume;
Injudicious fluid administration has been linked to fluid accumulation
IAP, intra-abdominal pressure; ICU, intensive care unit; IV, intravenous; IVC, syndrome with longer durations of mechanical ventilation, increased
inferior vena cava; PAOP, pulmonary artery occlusion pressure; PCO2 gap, risk of acute kidney injury, and prolonged hospital stays [1].
central venous–arterial pCO2 gradient; RRT, renal replacement therapy; US, This review, summarized in Fig. 1, highlights common misconcep-
ultrasound; VEXUS, venous excess ultrasound score. tions and frequently overlooked insights, and proposes practical
* Corresponding author at: Ziekenhuis aan de Stroom Campus Cadix, Department of guiding principles to help avoid these classic pitfalls.
Intensive Care Medicine, Kempenstraat 100, 2030 Antwerp, Belgium.
E-mail address: (N. Van Regenmortel).
https://dx.doi.org/10.1016/j.aicoj.2026.100074
Received 1 December 2025; Received in revised form 8 March 2026; Accepted 29 April 2026
2110-5820/© 2026 The Authors. Published by Elsevier Masson SAS on behalf of Société de Réanimation de Langue Française (French Intensive Care Society). This is
an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
, [(Fig._1)TD$IG]M. Vanden Eede and N. Van Regenmortel Annals of Intensive Care 16 (2026) 100074
Fig. 1. Five classic fluid pitfalls and five ways to do it better.
Five classic pitfalls in fluid therapy Underestimating hidden fluid sources
Confusing the distinct purposes of resuscitation, maintenance, and While fluid resuscitation often draws the most attention, it
replacement fluids represents only a small part of the total fluid volume ICU patients
receive. In practice, resuscitation fluids account for a mere 6–10%
In the high-stakes environment of shock, the administration of [5,6]. Frequently overlooked are background fluids, or “fluid creep” –
intravenous fluids is often viewed as universally beneficial, but this a term that encompasses flushes, line patency fluids and medication
assumption is dangerously flawed. A common clinical error is the diluents – which account for roughly one third of water and sodium
failure to distinguish between the three different reasons for which burdens administered to ICU patients. Fluid creep can easily provide
intravenous fluids are prescribed: resuscitation fluids in case of shock, enough daily fluid to make maintenance fluids redundant—but this
maintenance fluids to cover basic needs and replacement fluids to overlap often goes unrecognized. An observational study found that
correct past or ongoing fluid losses. These are three very distinct ICU patients received a median of 645 mL of these hidden fluids and
indications and should be in separate mental buckets, each with their an additional 2592 mL of discretionary fluids over just 24 h [7].
own considerations. While it is increasingly accepted that resuscita- Failing to account for this hidden volume could turn your
tion fluids must be isotonic and administered as a rapid bolus, it is maintenance strategy into an accidental flood.
often overlooked that maintenance fluids should closely match the Our advice: Always account for fluid creep (and implement this in
water and electrolyte requirements of a healthy human diet. fluid balance calculations). It may render additional maintenance or
Typically, these needs include approximately 25–30 mL/kg/day of even replacement fluids unnecessary.
water (making maintenance fluids unnecessary when other fluid
sources or oral intake are sufficient), 1 mmol/kg/day of sodium and Focusing on volume while overlooking sodium as the driver of fluid
potassiumand 50−100 g of glucose [2,3]. Replacement fluids cover accumulation
losses that may originate from various sources [4]. Fluids used to
replace these losses should closely match the composition of the fluid While the sheer volume of fluid administered in the ICU often gets
lost. Using the same fluid to treat all types of losses will inevitably the blame for fluid overload, excessive sodium intake may play an
disrupt homeostasis. Table 1 summarizes the composition of various even more important role. From a physiological standpoint, the
types of fluid losses and provides corresponding recommendations for kidneys regulate water balance efficiently and rapidly, yet respond
fluid replacement. A further contributor to fluid accumulation is the surprisingly slowly to changes in sodium intake. Classic experiments
common omission of stop dates or reassessment intervals in demonstrated that, in healthy individuals, increasing sodium intake
maintenance and replacement prescriptions. Maintenance and from 0.5 g/day to 3.2 g/day (a common amount in many parts of the
replacement fluid orders often continue unnoticed for days, with world) required roughly five days for the kidneys to re-establish
no automatic trigger to stop or review them: a “set it and forget it” sodium balance, a relatively slow adaptive process despite the
approach. Without clear tracking and accountability, fluid accumu- kidneys’ high filtration capacity [8]. During this period, fluid
lates quietly, making meaningful fluid stewardship nearly impossible. retention led to a weight gain of over 1 kg. Once the sodium load
Our advice: Clearly differentiate between resuscitation, mainte- was reduced, shedding this weight took just as long. It is readily
nance, and replacement fluids, as each fulfills a distinct physiological apparent that even isotonic fluids— including balanced alternatives to
purpose. Avoid using a one-size-fits-all approach, which can disrupt NaCl 0.9%—can exceed a patient’s typical daily sodium intake with no
homeostasis and unnecessarily increase electrolyte load. more than one liter [9].
2
Contents lists available at ScienceDirect
Annals of Intensive Care
journal homepage: www.elsevier.com/locate/aicoj
Review
Unnecessary fluid therapy in patients with shock: Five classic fluid pitfalls
and five ways to do it better
Martin Vanden Eedea, Niels Van Regenmortelb,c,*
a
Ziekenhuis aan de Stroom Campus Middelheim, Department of Emergency Medicine, Lindendreef 1, 2020 Antwerpen, Belgium
b
Ziekenhuis aan de Stroom Campus Cadix, Department of Intensive Care Medicine, Kempenstraat 100, 2030 Antwerp, Belgium
c
Antwerp University Hospital, Department of Intensive Care Medicine, Drie Eikenstraat 655, 2650 Edegem, Belgium
ARTICLE INFO ABSTRACT
Keywords: Intravenous fluid therapy remains a cornerstone of shock management, yet is frequently misapplied.
Shock Unnecessary administration can lead to avoidable harm, including fluid accumulation, electrolyte
Fluid therapy disturbances, and delayed recovery. Despite good intentions, clinicians often fall into predictable patterns
Fluid overload that drive overinfusion. Recognizing and correcting these habits is an important step toward safer and more
Maintenance fluids
effective fluid management, which may contribute to better patient outcomes.
Resuscitation fluids
Sepsis
This narrative review highlights five recurring pitfalls in fluid management: confusion between
Pathophysiology resuscitation, maintenance, and replacement indications; failure to account for hidden fluid sources;
Volume status underestimation of the impact of sodium burdens; reflexive fluid administration in response to misinterpreted
Fluid stewardship markers such as hyperlactatemia, low central venous pressure or reduced urine output; and finally, a narrow
focus on fluid responsiveness without consideration of fluid tolerance.
To address these challenges, we propose a pragmatic, physiology-based approach to fluid stewardship. Key
strategies include adopting a phase-based model for fluid therapy, minimizing unnecessary sodium and
chloride exposure, interpreting fluid balance data with caution, initiating early vasopressor support when
appropriate, and employing structured de-resuscitation (and preventive) strategies rather than relying solely
on loop diuretics.
Thoughtful, physiology-driven fluid therapy requires more than reflexes, fixed volumes and flowcharts, it
demands context-sensitive, physiology-informed decision-making. By recognizing common mistakes and
adopting simple yet powerful principles, clinicians can shift from automatic to analytic and from flood to
finesse.
Background Historically, early goal-directed therapy was considered standard
of care, guided by protocols aiming to optimize arterial oxygen
Intravenous fluid therapy is often initiated with the best intentions. delivery. In practice, this often translated into rapid fluid administra-
However, when resuscitation fluids are administered without clear tion and a focus on urine output as surrogate indicators of treatment
physiological targets, or when maintenance fluids are misused in the success. A continuous stream of evidence in recent years has shown
context of shock, these good intentions can harm the patient. that various aspects of fluid therapy—such as fluid type, sodium
content, dosing strategies and guiding parameters such as fluid
responsiveness—can influence outcomes and that inappropriate or
Abbreviations: AKI, acute kidney injury; CVP, central venous pressure; DPB,
excessive fluid administration may be harmful in ICU patients
diastolic blood pressure; EVLW, extravascular lung water; FR, fluid
responsiveness; FT, fluid tolerance; GEDV, global end diastolic volume;
Injudicious fluid administration has been linked to fluid accumulation
IAP, intra-abdominal pressure; ICU, intensive care unit; IV, intravenous; IVC, syndrome with longer durations of mechanical ventilation, increased
inferior vena cava; PAOP, pulmonary artery occlusion pressure; PCO2 gap, risk of acute kidney injury, and prolonged hospital stays [1].
central venous–arterial pCO2 gradient; RRT, renal replacement therapy; US, This review, summarized in Fig. 1, highlights common misconcep-
ultrasound; VEXUS, venous excess ultrasound score. tions and frequently overlooked insights, and proposes practical
* Corresponding author at: Ziekenhuis aan de Stroom Campus Cadix, Department of guiding principles to help avoid these classic pitfalls.
Intensive Care Medicine, Kempenstraat 100, 2030 Antwerp, Belgium.
E-mail address: (N. Van Regenmortel).
https://dx.doi.org/10.1016/j.aicoj.2026.100074
Received 1 December 2025; Received in revised form 8 March 2026; Accepted 29 April 2026
2110-5820/© 2026 The Authors. Published by Elsevier Masson SAS on behalf of Société de Réanimation de Langue Française (French Intensive Care Society). This is
an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
, [(Fig._1)TD$IG]M. Vanden Eede and N. Van Regenmortel Annals of Intensive Care 16 (2026) 100074
Fig. 1. Five classic fluid pitfalls and five ways to do it better.
Five classic pitfalls in fluid therapy Underestimating hidden fluid sources
Confusing the distinct purposes of resuscitation, maintenance, and While fluid resuscitation often draws the most attention, it
replacement fluids represents only a small part of the total fluid volume ICU patients
receive. In practice, resuscitation fluids account for a mere 6–10%
In the high-stakes environment of shock, the administration of [5,6]. Frequently overlooked are background fluids, or “fluid creep” –
intravenous fluids is often viewed as universally beneficial, but this a term that encompasses flushes, line patency fluids and medication
assumption is dangerously flawed. A common clinical error is the diluents – which account for roughly one third of water and sodium
failure to distinguish between the three different reasons for which burdens administered to ICU patients. Fluid creep can easily provide
intravenous fluids are prescribed: resuscitation fluids in case of shock, enough daily fluid to make maintenance fluids redundant—but this
maintenance fluids to cover basic needs and replacement fluids to overlap often goes unrecognized. An observational study found that
correct past or ongoing fluid losses. These are three very distinct ICU patients received a median of 645 mL of these hidden fluids and
indications and should be in separate mental buckets, each with their an additional 2592 mL of discretionary fluids over just 24 h [7].
own considerations. While it is increasingly accepted that resuscita- Failing to account for this hidden volume could turn your
tion fluids must be isotonic and administered as a rapid bolus, it is maintenance strategy into an accidental flood.
often overlooked that maintenance fluids should closely match the Our advice: Always account for fluid creep (and implement this in
water and electrolyte requirements of a healthy human diet. fluid balance calculations). It may render additional maintenance or
Typically, these needs include approximately 25–30 mL/kg/day of even replacement fluids unnecessary.
water (making maintenance fluids unnecessary when other fluid
sources or oral intake are sufficient), 1 mmol/kg/day of sodium and Focusing on volume while overlooking sodium as the driver of fluid
potassiumand 50−100 g of glucose [2,3]. Replacement fluids cover accumulation
losses that may originate from various sources [4]. Fluids used to
replace these losses should closely match the composition of the fluid While the sheer volume of fluid administered in the ICU often gets
lost. Using the same fluid to treat all types of losses will inevitably the blame for fluid overload, excessive sodium intake may play an
disrupt homeostasis. Table 1 summarizes the composition of various even more important role. From a physiological standpoint, the
types of fluid losses and provides corresponding recommendations for kidneys regulate water balance efficiently and rapidly, yet respond
fluid replacement. A further contributor to fluid accumulation is the surprisingly slowly to changes in sodium intake. Classic experiments
common omission of stop dates or reassessment intervals in demonstrated that, in healthy individuals, increasing sodium intake
maintenance and replacement prescriptions. Maintenance and from 0.5 g/day to 3.2 g/day (a common amount in many parts of the
replacement fluid orders often continue unnoticed for days, with world) required roughly five days for the kidneys to re-establish
no automatic trigger to stop or review them: a “set it and forget it” sodium balance, a relatively slow adaptive process despite the
approach. Without clear tracking and accountability, fluid accumu- kidneys’ high filtration capacity [8]. During this period, fluid
lates quietly, making meaningful fluid stewardship nearly impossible. retention led to a weight gain of over 1 kg. Once the sodium load
Our advice: Clearly differentiate between resuscitation, mainte- was reduced, shedding this weight took just as long. It is readily
nance, and replacement fluids, as each fulfills a distinct physiological apparent that even isotonic fluids— including balanced alternatives to
purpose. Avoid using a one-size-fits-all approach, which can disrupt NaCl 0.9%—can exceed a patient’s typical daily sodium intake with no
homeostasis and unnecessarily increase electrolyte load. more than one liter [9].
2
