Changes in carotid corrected flow time in guiding fluid resuscitation in septic patients

Abstract

Introduction Accurate estimation of intravascular volume status is important in the resuscitation of patients in ICUs. Although intensive fluid therapy in patients with life-threatening volume depletion can prevent death and end-organ damage, volume overload is known to result in increased mortality, morbidity, and duration of hospital stay. Ultrasonography has become a common diagnostic choice in assessment of fluid status in septic patients. This method is noninvasive, easy to learn, and provides real-time assessment at the patient’s bedside. Various ultrasound modalities have been developed to provide accurate and minimally invasive assessment of volume status. In this regard, one of the most promising methods is the evaluation of the blood flow velocity waveform in the descending thoracic aorta via a nonimaging Doppler probe. This modality is based on calculating the systolic flow time with cycle time correction [corrected flow time (FTc)]. FTc is known to be directly associated with volume status. FTc measurement in carotid artery is a completely noninvasive and much more feasible approach. Aim To compare the use of ultrasonography in the measurement of the changes in carotid FTc with echocardiography in the assessment of changes in heart dynamics to assess changes in volume status before and after passive leg raising (PLR) in septic patients. Patients and methods A total of 40 septic patients, including 18 (45.5%) patients as fluid responders and 22 (54.5%) patients as nonfluid responders, were included. Increased FTc by 7 ms, as well as 10% increase in stroke volume was considered to be fluid responsive. Results Our study results showed that 45.5% (n=18) of study population were fluid responders. The PLR test could assess fluid responsiveness with a specificity of 100% and sensitivity of 95% at a cutoff of 10.6% change in CO to predict fluid responsiveness. The study showed a statistically significant moderate positive correlation between CCA FTc and the percent of change in CO measured by echocardiography. An agreement analysis was formed. We concluded that there was a strong relation between change in carotid corrected blood flow and change in COP before and after PLR, with P value less than 0.001. Therefore, we can use this parameter to predict fluid responsiveness after PLR. Conclusions Carotid artery blood flow is a promising noninvasive and easy-to-perform tool for the evaluation of fluid responsiveness in critically ill septic patients. The PLR maneuver has demonstrated excellent performance for predicting fluid responsiveness. It is simple to perform but requires a reliable system of carotid corrected blood flow (COP) monitoring able to quantify the short-term changes.