COVID19 Critical Care

Importance of Hemodynamic Monitoring

Patients admitted for critical care are typically either suffering from single/multiple organ failure or at least considered to be at risk. This includes patients who have undergone major surgery and/or trauma. Importantly though, it includes patients with a range of physiological challenges induced by, for example, acute viral infection such as Covid19.

A major contributary factor to organ failure is hemodynamic instability. This is because it is likely to result in a mismatch between oxygen delivery and demand.

Therapeutic approaches to COVID-19 are rapidly evolving. In recent days the American College of Cardiologists has issued its own bulletin discussing the risk of complications in COVID-19 patients with underlying cardiovascular conditions. The guidance states that “for patients with heart failure or volume overload conditions, copious fluid administration for viral infection should be used cautiously and carefully monitored.”

This implies the need for close control over circulating fluid status and avoidance of hemodynamic instability. Hemodynamic instability in practice derives from a variation in circulating volume (e.g. hypovolaemia), cardiac function, and/or vascular tone (e.g. vasoplegic shock in sepsis).

Covid19 patients: achieving hemodynamic stability

Clinicians can achieve the desirable goal of hemodynamic stability by adopting a host of measures. These include regular clinical examination and monitoring of basic vital parameters (heart rate, blood pressure, central venous pressure, peripheral and central venous oxygen saturation, and respiratory variables) and urine output. But when these fail, hemodynamic monitoring is the best tool to safely and effectively guide fluid management and vasopressor/inotropic support.

Critical care origins of EDM+

It’s no coincidence that the esophageal Doppler technique embodied in Deltex’s EDM+ system was developed by one of the world’s leading intensive care doctors, Professor Mervyn Singer of University Hospital London. He subsequently created a nomogram for converting the Doppler data into recognizable cardiac output parameters. Indeed it was Prof Singer who originally suggested using the Frank-Starling Law-derived 10% stroke volume algorithm to underpin the administration of fluid. The Stroke Volume Optimisation (SVO) protocol normalizes stroke volume without the risk of fluid overload.

Deltex’s EDM+ system collects its data directly from the descending aorta in real time. As such it is the only system that has the precision necessary to guide a 10% SVO protocol. This is why the application of Doppler is the very definition of hemodynamic management