Persistent Thirst and Its Clinical Correlates in Critically Ill Adults: A Prospective Observational Study

Thirst is a common and distressing symptom among critically ill patients, yet it is often under-assessed and inadequately managed in intensive care units (ICUs). Evidence on changes in thirst during ICU stay and factors associated with its persistence remains limited.

To examine changes in thirst intensity during ICU stay and identify clinical factors associated with persistent thirst in critically ill adults.

In this prospective observational study in South Korea, thirst intensity was assessed using an 11-point numeric rating scale within 72 h of ICU admission (T1) and within 24 h prior to ICU discharge (T2). Persistent thirst was defined as a T2 score of ≥ 4. Univariable and multivariable logistic regression analyses identified factors associated with persistent thirst, and linear regression examined factors associated with thirst intensity at T1.

Mean thirst intensity significantly decreased from T1 to T2 (4.69 ± 2.93 vs. 1.93 ± 2.46, p < 0.001). However, persistent thirst was observed in 22.5% (16/71) of patients. In multivariable analysis, invasive mechanical ventilation (adjusted OR 5.16, 95% CI 1.18-22.53, p = 0.029) was independently associated with persistent thirst, whereas early net fluid balance showed an inverse association (adjusted OR 0.85, 95% CI 0.76-0.94, p = 0.002). No clinical factor was independently associated with thirst intensity at T1.

Although thirst intensity decreased during ICU stay, persistent thirst remained relevant in a subset of critically ill patients. Invasive mechanical ventilation and negative fluid balance were independently associated with persistent thirst, highlighting the need for systematic assessment and targeted management.

Thirst assessment should be incorporated into nursing practice, particularly for patients receiving invasive mechanical ventilation and those experiencing negative fluid balance. Early identification of high-risk patients may facilitate timely implementation of individualized, non-fluid-based comfort interventions while maintaining appropriate fluid management.