SSMRF Seed Grant Supports A/Professor Konstantin Yastrebov’s CHAISE Investigation

In 2013, SSMRF supported Associate Professor Konstantin Yastrebov’s CHAISE (Comparative Haemodynamic Assessment: InvaSive and Echocardiographic techniques) investigation with a $25,000 Seed Grant.

Intravenous fluids are routinely and liberally used in emergency and critical care medicine. This therapy is essential in treating many types of shock and intensive care pathology. However, there is a growing body of evidence that administration of excessive amounts of intravenous fluids may result in harm and even death. Current clinical practice lacks precise methods to estimate strictly needed amount of fluids for each patient and relies on indirect signs and highly invasive haemodynamic measurements. Cardiac ultrasonography has been increasingly utilised in intensive care practice to assess fluids status. It gained popularity especially due to its non-invasive nature, ability to repeat studies at the patient’s bedside without side-effects.

CHAISE investigation compared several highly invasive methods and cardiac ultrasound in estimation of how well cardiovascular system is filled with blood in critically ill patients. This was the first study to examine relationship between echocardiography and mean systemic filling pressure (the gold standard for estimating amount of blood in each cardiovascular system). Fifty critically ill patients were eventually investigated in two major Sydney hospitals.

The most important finding of this study was the inability of neither basic nor highly advanced cardiac ultrasound performed at a single given time to accurately estimate fluid status in critically ill patients. The study however confirmed that cardiac ultrasound could reliably replace some highly invasive measurements for calculating estimates of filling.

These findings helped to change some aspects of teaching and widely accepted practice relating to the use of cardiac ultrasonography in guiding fluid therapy. While not all invasive measurements can be replaced with cardiac ultrasonography, it may reliably substitute some highly invasive techniques in research and clinical practice in order to calculate mean systemic filling pressure, largely expanding opportunities for haemodynamic monitoring.

The CHAISE study has been now completed and published on 17 March 2020 in Nature Scientific Reports article “Comparison of echocardiographic and invasive measures of volaemia and cardiac performance in critically ill patients”

The following information has been obtained from the article.

Method and Patients
Between February 2016 and November 2017, Associate Professor Konstantin Yastrebov’s and the CHAISE study research team enrolled 50 adult patients who were mechanically ventilated, sedated, and admitted to two university affiliated, multidisciplinary Intensive Care Units (ICUs) in Sydney who required invasive monitoring of arterial pressure, central venous pressure and cardiac output as part of routine care.

Results
“The study demonstrates good potential to expand the use of analogue mean systemic filling pressure and derived global heart efficiency based on non-invasive echocardiographic measures of cardiac output to a wider cohort of intensive care patients provided that adequate echocardiographic views can be obtained in addition to mean arterial pressure and invasive central venous pressure. Moderate correlations between invasive and echocardiographic measurements of cardiac output in our investigation are aligned with the previous reports that these techniques are not interchangeable in intensive care patients.”

“The study provides caution to clinicians using and relying on static echocardiographic parameters to estimate volume status of their patients, particularly in dynamic situations and under conditions of limited echocardiographic imaging.”

Conclusion
Static echocardiographic variables did not reliably reflect the volume state as defined by estimates of mean systemic filling pressure. There was no statistical or clinically robust relationship between static echocardiographic variables of cardiac systolic function and global heart efficiency. Echocardiography remains valuable in estimating volume state by the ability to measure cardiac output for the calculation of analogue mean systemic filling pressure.

Associate Professor Konstantin Yastrebov
MBBS (Hons), PhD, FCICM, FACRRM, DDU
Senior Specialist in Intensive Care
St George and Prince of Wales Hospitals
Head, Critical Care Echocardiography Program
The St George Hospital
Gray Street, Kogarah,
Sydney, NSW, 2217, Australia
Conjoined Appointee UNSW