Precision and Practicality in Fluid Responsiveness

• In ICU
• Thu, 19 Mar 2026

At the 45th ISICEM in Brussels, Prof Sheila Myatra spoke about fluid responsiveness in ICU patients with acute circulatory failure, emphasising its critical role in guiding safe and effective fluid therapy. While intravenous fluids are a first-line intervention, only around 50% of patients are true fluid responders, meaning their cardiac output increases by at least 15% after fluid administration. Both over-resuscitation (leading to increased morbidity and mortality) and under-resuscitation (resulting in poor perfusion) carry significant risks, making accurate assessment essential.

Fluid responsiveness should not be assessed at initial ICU presentation, as most patients in shock initially respond to fluids. Instead, it should be evaluated after initial resuscitation, when clinicians must decide whether to administer more fluids or initiate vasopressors. At this stage, clinical parameters alone are insufficient, and specific tests are required—though these can be complex and time-consuming.

Prof Myatra reviewed key methods for assessing fluid responsiveness, their limitations, and recent advances. She also highlighted new consensus guidelines from the European Society of Intensive Care Medicine, which aim to standardise practice and provide practical bedside guidance. A central recommendation is the use of the passive leg raising test, which is widely applicable and avoids many limitations of heart–lung interaction-based tests (e.g. issues with low tidal volume, arrhythmias, or poor lung compliance). Other recommended tests include the end-expiratory occlusion test, mini-fluid challenge, and the tidal volume challenge developed by her team.

Fluid responsiveness is only one factor in decision-making and does not automatically justify further fluid administration. Even in responders, clinicians must weigh the risks of additional fluids; if risks are high, vasopressors may be a safer alternative. Despite available methods, fluid administration in practice remains variable and often arbitrary, with many clinicians not routinely assessing responsiveness at the bedside, highlighting the need for guidelines and greater awareness.

The complexity and resource requirements of current tests, particularly the need for real-time cardiac output monitoring, limit their use in some settings. This underscores the need for simpler, cost-effective, and reliable bedside tools. The tidal volume challenge addresses this gap, especially as modern ICU practice favours lower tidal volumes (≈6 ml/kg), where traditional measures like PPV and SVV become unreliable. It is particularly valuable in resource-limited environments where avoiding unnecessary fluid and mechanical ventilation is crucial.

Overall, Prof Myatra stressed that fluid responsiveness testing must be used thoughtfully, integrated with risk assessment, and supported by simpler, more accessible methods to improve patient outcomes.

Source: ISICEM
Image Credit: iStock