Investigate the effects of fluid bolus therapy on Emergency department

Investigate the effects of fluid bolus therapy on Emergency department

Fluid therapy is commonly prescribed to patients in the Emergency Department. There is however increasing recognition that particularly in the treatment of critically ill patients, fluid therapy may have significant unintended side effects. Therefore the concept of a more goal-directed approach to fluid therapy with optimisation of intravascular volume and tissue perfusion has increasing research and clinical interest with some association with improved outcomes. This way, clinicians can then match intravascular volume status with a measure of contractility of the heart in order to optimise cardiovascular physiology as part of an overall approach to resuscitation.

The ability to assess intravascular fluid status and therefore fluid responsiveness within the emergency department however is difficult. Clinical examination unreliable and the insertion of gold-standard invasive devices such as a Swann-Ganz catheter both impractical and associated with a not-insignificant rate of complications. Instead, non-invasive, relatively inexpensive, versatile and repeatable devices which allow dynamic assessment of many emergency medicine clinical questions including intravascular fluid volume status can be helpful.

The Ultrasound Cardiac Output Measurement (USCOM) device is a continuous wave doppler ultrasound instrument which measures cardiac output (CO) by using an assumption that the diameter of the aortic and pulmonary valves has a robust relationship with patient height, and therefore makes CO measurement straightforward and convenient. The USCOM device has achieved similar agreement with invasive bolus thermodilution methods of CO measurement to other minimally- and non- invasive techniques[2]. The USCOM 1A is being increasingly used in critical care and emergency settings to give direct measurements of central haemodynamic variables.

We plan to use the USCOM device as part of clinical management to non-invasively measure physiological variables of patients presenting to the emergency department in order to examine the effect of intravenous fluid therapy on inotropy index and other physiological variables. We then plan to derive predictive models to determine the utility of inotropy index on predicting fluid responsiveness.