Why Cardiac Preload?

It’s the holy grail for ICU fluid management.

You get called in because the patient’s Blood Pressure (BP) is low. Should you give fluids? BP, urine output, lactate, and cardiac output numbers are available, but these indirect methods provide little insight into cardiac performance and can be misleading targets for resuscitation.

Without knowing Preload right then and there, you are forced to make a decision and direct fluid therapy based on inadequate information. Without knowing if RV function is normal or not, just pushing volume may cause more harm than good.

How do you know what is right for the patient?

grouped preload measured annotated

Consider the therapeutic value of seeing the heart directly.

Preload is cardiac filling, the amount the heart is stretched before pumping. The best measurement of Preload is the size of the left ventricle (LV) just before contracting, or LV end diastolic volume (LVEDV). LVEDV is the holy grail in hemodynamic management, since that’s what determines everything else, including BP and cardiac output. Hemodynamic Ultrasound provides a very simple measure, namely LVEDA (left ventricular end diastolic area), which is a well studied and immediately useful measure of cardiac filling in critically ill patients.

Because if you can’t see the heart…

Direct visualization of the heart shows changes in cardiac function faster than any surrogate markers of end organ perfusion.  And if you can’t see the heart, there’s the added risk of falling down a cascade:

  • Indirect data: misidentify the cause
  • Imprecise therapy: assumption-led decisions
  • Prolonged instability: prolonged LOS
  • Poor clinical outcomes: lower survival rates

Click here for a video of our fluid management algorithm.