Sat27November0445PM 30

Which of the following measurements is the most accurate method of predicting fluid responsiveness?

(Please select 1 option)

Central venous pressure measurement in a ventilated patient

Pulse pressure variation (PPV) in a spontaneously breathing patient

Change in superior vena cava diameter in a spontaneously breathing patient

Change in stroke volume following passive straight leg raise Correct

Stroke volume variation (SVV) in a patient in fast atrial fibrillation

Explanation

Dynamic tests of fluid responsiveness include pulse pressure variation (PPV), stroke volume variation (SVV), superior vena cava diameter variation (threshold 36%) and the end-expiratory occlusion test.

PPV is derived peripherally from the arterial pressure waveform.

Stroke volume variation (SVV) is peripherally derived through pulse contour analysis of the arterial waveform. Both PPV and SVV have a threshold of 12% but are of limited value because they are not be used in patients who are spontaneous breathing, have cardiac arrhythmias (i.e. atrial fibrillation) and in ventilated patients with low tidal volumes and lung compliance. Similarly, superior vena cava diameter variation is only accurate in ventilated patients.

The accuracy of tests of fluid responsiveness can be determined by calculating the area under the receiver operating characteristic curve (UROC). This is obtained by plotting the sensitivity of the parameter in predicting fluid responsiveness vs. 1-specificity.

Using CVP, LVEDA, SVV and PPV under optimal conditions the ability to determine the need for fluid is best with PPV>SVV>LVEDA and then CVP.

The passive leg raising (PLR) manoeuvre is a method of altering left and right ventricular preload in conjunction with real-time measurement of stroke volume. It is simple, quick, relatively unbiased, and accurate bedside test to guide fluid management and to potentially avoid fluid overload. The diagnostic threshold is about 10% change in stroke volume.

Central venous pressure (CVP) is a static test of preload (not preload responsiveness) and a key determinant of cardiac function. The left ventricular end-diastolic area (LVEDA) is an alternative static test of fluid responsiveness and derived using echocardiography.

Reference:

Prediction of fluid responsiveness: an update.

Xavier Monnet, Paul E. Marik and Jean-Louis Teboul

Annals of Intensive Care 2016. 6:111

Answer Statistics

1

3%

2

6%

3

4%

4

88%

5

1%

Times answered: 340