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Dynamic Measures of Intravascular Volume Assessment
The resuscitation of a patient in shock often requires the administration of intravenous fluid. Excessive fluid resuscitation can lead to worsening pulmonary edema, systemic edema, acid-base disturbances, as well as many other complications. There are a myriad of techniques to try and figure out if the patient needs more intravascular volume, but each has it’s pitfalls.
Recently, experts have recommend that we move away from using static measures of preload assessment such as central venous pressure (CVP) and instead focus on using dynamic measures for volume responsiveness.
Volume Responsiveness Defined: An increase of stroke volume of 10-15% after a 500 mL IV crystalloid bolus over 10-15 minutes.
Below is a chart describing key values, requirements, and contraindications for each of these dynamic measures of non-invasive intravascular volume assessment.
Important notes: PPV and SVV require the patient to be intubated with controlled tidal volumes. Arrhythmias and right heart failure make many of these measures invalid (except for PLR). Other methods of assessment not discussed include systolic pressure variation, left ventricular outflow track velocity time integral (LVOT VTI), and end-expiratory occlusion pressure (EEO).
Bottom Line: None of these measures are perfect and shouldn't be used in isolation to determine if the patient’s “tank is full”. Combine clinical judgment with these measures to get a best estimate of whether or not to give that next fluid bolus.
Reference
1. Enomoto TM, Harder L. Dynamic indices of preload. Crit Care Clin. 2010;26(2):307-21,
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