Carotid Ultrasound in Sepsis and Hypotension (CUSH)

MGH Ultrasound

Septic shock is a common presentation to the emergency department and critical care units that is associated with high mortality and severe organ impairment. In the early stage of septic shock, there is often not enough fluid in the blood vessels and this impairs delivery of oxygen to vital organs including brain, lungs, heart and kidneys. Therefore, giving patients fluids directly into their blood vessels intravenously (IV) is one of the critical actions in initial treatment of patients with septic shock. The patients’ responses to the initial IV fluid therapy is variable; almost half of these patients fail to adequately respond to the fluid therapy. Occasionally, in cases with preexisting heart failure, and in those with severe respiratory problems, too much fluid can be dangerous as it may spill over into the lungs and make it harder for patients to breathe.

In this study, we propose the use of ultrasound of the arteries in the neck as a means of determining how much fluid a patient has in their vessels, and whether additional fluid is likely to help or harm the patient. Advanced ultrasound of the heart is sometimes used for these purposes but requires extensive training and specialized techniques. Carotid ultrasound, on the other hand, is an easy to learn technique performed with standard equipment that is easily accessible to most emergency and critical care physicians. In this technique we look at the blood vessels in the neck and by measuring flow patterns we can infer information about the patient’s blood volume status. Previously, we studied the use of carotid ultrasound and flow to detect patients’ volume status in a different setting. The time required to complete a cycle is proportionally related to the amount of fluid that pumped into the carotid artery. A lower volume will pump in a shorter time and a larger volume will need more time to be ejected and to complete a cardiac cycle.

We will monitor the carotid blood flow over the duration of resuscitation to evaluate response to IV fluids. Repeating this measurement allows for the detection of the time required for a full volume restoration. We hypothesize that within conventionally defined septic shock, there are distinct hemodynamic profiles as detected by ultrasound that have prognostic and therapeutic implications.

A standardized protocol will be followed to measure carotid flow time and volume at the baseline and after a raising patients’ leg (which may also predict fluid responsiveness in these patients by transmitting blood from legs to the heart). We will repeat the ultrasound exams after IV fluids. We will identify which patients appropriately responded to IV fluids, which patients needed additional pharmacologic support of their blood pressure, and which patients received too much fluid.

We will identify patients who will have a proper blood flow time and volume, and will compare major adverse outcomes and mortality between those who responded fast to the fluid and those who failed to improve their carotid blood flow.

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