Fluid Responsiveness Through the Corrected Carotid Flow Time, Before and After Sternotomy

Perioperative fluid management is used to maintain the perfusion of vital organs, prevent hypovolemia, inadequate tissue perfusion, and tissue edema, and cardiovascular complications caused by the infusion of large amounts of blood and blood products. Optimal fluid management improves postoperative outcomes. However, excessive or inadequate fluid infusion increases morbidity. Traditional fluid therapy strategies are divided into three groups: liberal fluid therapy, restrictive fluid therapy, and goal-directed therapy (GDT). Fluid responsiveness refers to a patient's hemodynamic response to intravenous fluid loading and is defined as an increase of 10% or more in stroke volume (SV) or cardiac output (CO). Various parameters are used to assess fluid responsiveness. Static parameters have limited accuracy in predicting fluid responsiveness. Dynamic parameters such as stroke volume variation (SVV), pulse pressure variation (PPV), passive leg raising test (PLR), and end-expiratory occlusion test (EEOT) have been found to be more reliable in assessing fluid responsiveness. The pulse contour analysis method (PCA) continuously measures cardiac output by analyzing the arterial pressure waveform. The ProAQT/PulsioFlex system measures cardiac output by analyzing the arterial waveform without requiring calibration. Lung recruitment maneuvers (LRM) are techniques used in mechanically ventilated patients to prevent atelectasis and improve oxygenation. They have also been shown to assist in assessing fluid responsiveness. LRM methods include sustained inflation (SI), increased PEEP pressure, increased tidal volume, and targeted recruitment. The temporary increase in intrathoracic pressure during LRM can affect stroke volume variation and be used to assess fluid responsiveness. Corrected carotid flow time (FTc) is a non-invasive parameter calculated by normalizing the systolic ejection time in the carotid artery to heart rate. FTc can be measured using Doppler ultrasound. It is