Comparing Fluid Responsiveness Assessment Methods in Patients With Impaired Consciousness

"In mechanical ventilation, the Inferior Vena Cava's maximum diameter (IVCmax) is measured at peak inspiration, and minimum diameter (IVCmin) at expiration's end. The Distensibility Index (IVCDI) is calculated as \[(IVCmax - IVCmin) / IVCmin\] × 100%. In spontaneous breathing, IVCmax is the diameter at expiration's end, and IVCmin at inspiration's end. The Collapse Index (IVCCI) is \[(IVCmax - IVCmin) / IVCmax\] × 100%.~Clinically, an IVCDI/IVCCI ≥ 18% indicates a 'responder'. Values \< 18% denote 'non-responders'."

"In our protocol, patients lie flat, connected to a saline-filled system for intravenous infusion via a central venous catheter. The system, starting from the subclavian catheter, extends to the 2nd to 3rd intercostal space at the mid-axillary line. The tube's end is raised perpendicular to the bed until saline flow stops, marking the liquid level. The height from the mid-axillary line to this point is measured in millimeters. If the liquid column falls below the mid-axillary line, indicating continuous flow, the CVP is negative, and the catheter is closed to block air entry. CVP readings are taken at exhalation's end.~CVP interpretation:~* CVP ≤ 12 mmHg (16.3 cm H2O) indicates a responder.~* CVP \> 12 mmHg (16.3 cm H2O) indicates a non-responder."

"In our protocol, the patient starts flat for initial CVP measurement. Then, the bed is tilted to 45 degrees for the first measurements: Systolic/Diastolic Blood Pressure, Mean Arterial Pressure, and Pulse Pressure (Systolic - Diastolic). Next, the bed is adjusted to elevate the feet, creating a 135-degree angle between torso and legs. After 90 seconds, the second set of measurements, including CVP, is taken. The patient is then returned to the initial position.~Interpreting results:~A responder is indicated by:~* Over 10% Pulse Pressure (PP) increase in the second measurement;~* The ratio of PP change to CVP change (∆PP / ∆CVP) \> 1;~* Second measurement CVP ≤ 12 mmHg (16.3 cm H2O).~A non-responder is indicated by the presence at least one of the following:~* Less than 10% PP increase in the second measurement;~* The ratio of PP change to CVP change (∆PP / ∆CVP) ≤ 1;~* Second measurement CVP \> 12 mmHg (16.3 cm H2O)."

"In our clinical procedure, patients start horizontally for initial measurements: Systolic, Diastolic, Mean Arterial, Pulse Blood Pressures, and Central Venous Pressure (CVP). Then, they receive a balanced crystalloid solution at 4 ml/kg body weight at maximum permissible infusion rate. After infusion, a second measurement set identical to the first is taken.~Interpretation:~A responder is indicated by:~* Pulse Pressure (PP) increase \> 10% in second measurement;~* Ratio of PP change to CVP change (∆PP / ∆CVP) \> 1;~* Second CVP measurement ≤ 12 mmHg (16.3 cm H2O).~A non-responder is indicated by the presence at least one of the following:~* PP increase \< 10% in second measurement;~* Ratio of PP change to CVP change (∆PP / ∆CVP) ≤ 1;~* Second CVP measurement \> 12 mmHg (16.3 cm H2O)."

After assessing infusion therapy responsiveness, patients receive balanced crystalloid solutions at 1000 ml, infused at 15 ml/kg/hour, accounting for any prior infusions. Effectiveness evaluation follows, involving cardiac output reassessment (initially measured upon study enrollment). Effectiveness is determined by a ≥10% increase in cardiac output in the second measurement compared to the first. This is quantified as: \[(CO(after) - CO(before)) / CO(before)\] × 100% ≥ 10%, where CO(after) is the post-infusion cardiac output and CO(before) the pre-infusion output.