Change in End-Tidal Co₂ After Mini-Fluid Challenge to Determine Fluid Responsiveness.

Area of Science:

• Critical Care Medicine
• Hemodynamics
• Mechanical Ventilation

Background:

• Distributive shock is a significant cause of mortality in intensive care units (ICUs).
• Intravenous fluid resuscitation is crucial for improving cardiac output and organ perfusion in distributive shock.
• Noninvasive methods to assess fluid responsiveness are needed for optimizing resuscitation strategies.

Purpose of the Study:

• To evaluate the predictive value of changes in end-tidal carbon dioxide (ΔETco2) after a mini-fluid challenge for fluid responsiveness.
• To determine if ΔETco2 can serve as a noninvasive marker for guiding fluid administration in mechanically ventilated patients with distributive shock.

Main Methods:

• A single-center prospective study conducted in a medical ICU from 2019 to 2021.
• Thirty-eight mechanically ventilated patients with distributive shock were included.
• Fluid responsiveness was assessed using bioreactance, with a ≥10% increase in stroke volume index (SVI) defining responsiveness. Changes in ETco2 (ΔETco2) after a 250 mL fluid bolus were measured.

Main Results:

• The sensitivity of ΔETco2 ≥ 2 mm Hg for predicting fluid responsiveness (ΔSVI ≥ 10%) was 20.0%, with a specificity of 91.3%.
• The area under the receiver operating characteristic curve was 0.62, indicating limited discriminatory power.
• These results suggest a poor performance of ΔETco2 in identifying fluid responders.

Conclusions:

• A ΔETco2 of ≥ 2 mm Hg following a mini-fluid challenge demonstrates limited accuracy in predicting fluid responsiveness in intubated patients with distributive shock.
• The findings indicate that this method is not a reliable noninvasive tool for guiding fluid resuscitation in this patient population.
• Further research may be needed to identify more effective noninvasive predictors of fluid responsiveness in distributive shock.