Carotid Artery Blood Flow in Young Children Aged 0-5 Years in Relation to Blood Pressure and Cardiac Output During Anesthesia and Surgery

Blood pressure is routinely used as a surrogate for cardiovascular status during pediatric anesthesia. However, arterial blood pressure represents only one component of the circulation and may not directly reflect cardiac output or blood flow to individual organs. This is particularly relevant in infants and young children, in whom cardiovascular physiology and normal blood pressure values change substantially with age.

Blood flow in the common carotid artery can be assessed non-invasively using Doppler ultrasound. Because the carotid arteries contribute substantially to cerebral blood supply, measurement of carotid artery blood flow may provide additional information about changes in organ-directed blood flow during anesthesia. The CARFLOW study will investigate the relationship between Doppler ultrasound-derived common carotid artery blood flow, arterial blood pressure, and cardiac output in young children undergoing anesthesia and surgery.

Common carotid artery blood flow will be assessed using Doppler ultrasound, with the ultrasound probe positioned over the right common carotid artery just above the clavicle. Measurements will be obtained before induction of anesthesia, after induction and securing of the airway, and repeatedly during anesthesia. Additional measurements will be performed when blood pressure decreases below a predefined threshold and following clinically indicated treatment intended to increase blood pressure. Blood pressure monitoring and all decisions regarding treatment will remain part of routine clinical care.

In children managed with tracheal intubation, cardiac output will also be assessed using a non-invasive capnodynamic method based on controlled variations in carbon dioxide elimination during mechanical ventilation. This will allow simultaneous assessment of carotid artery blood flow, blood pressure, and cardiac output.

The study is intended to characterize how carotid artery blood flow varies during anesthesia in young children and how these changes relate to changes in blood pressure and cardiac output. The collected measurements will also provide data for describing carotid artery blood flow across the studied age range and may contribute to the development of reference values for carotid artery blood flow during pediatric anesthesia.