I have covered many things on this page, including resuscitation and fluid responsiveness. Fluid responsiveness is a patient being given a certain amount of fluid, or a passive leg raise to assess how that will increase the cardiac output/index or stroke volume. This post will discuss stroke volume variation (SVV) and how it predicts fluid responsiveness. The objective is to avoid drowning our patients with too much fluid. I have covered many aspects of my page’s Resuscitation and Fluid Responsiveness category here. There’s also an entire blog post on Fluid Resuscitation HERE that I’ve been working on.

What is Stroke Volume Variation (SVV)?

Stroke volume variation measures the change in stroke volume (SV) that occurs in respiration in patients. The heart-lung interaction induces this change. It is measured from the stroke volume component of the arterial waveforms and calculated. I’ll let you know more about the calculation shortly.

Why is Stroke Volume Variation important?

SVV is a dynamic form of assessing for volume responsiveness in patients on mechanical ventilation who need IV fluids resuscitation. It predicts the ability for there to be a change in the stroke volume with a fluid bolus. The major downside to this methodology is that you need some sort of device, such as pulse contour analysis or bioreactance, to sort this out. You’ll need an arterial line for pulse contour analysis (except for one particular device to my knowledge). I am familiar with one of these devices, although I will not divulge any further information for the sake of possible bias. Reemphasizing that patients need to be on mechanical ventilation is also essential.

What is the Stroke Volume Variation (SVV) Equation?

SVV= (SVmax – SVmin) / SVmean

SVV is calculated as the difference between the stroke volume on inspiration and expiration in the respiratory cycle. Fortunately, we don’t have to do it by hand these days. The machine/device does it for us, and we get a pretty number.

What Stroke Volume Variation (SVV) is considered “normal”?

Depending on the literature, a patient predicted to be volume responsive will have an SVV > 13% in most literature, but some will say > 10%. In my practice, I use the former. The normal range of stroke volume variation is < 13%. One could interpret the number that if it’s over 13%, they could potentially benefit from a fluid bolus.

Does SVV Predict Fluid Responsiveness?

A meta-analysis looked at 568 patients in 23 different studies using various devices. The correlation coefficient to fluid responsiveness was 0.718, meaning a “highly positive correlation.” The AUC of using SVV for fluid responsiveness is 0.84. 0.8-0.9 is considered “excellent”. It’s not all sunshine and roses, though. I know we’re rusty on our stats.

How is SVV measured?

There are various ways to assess the SVV:

• Arterial waveform analysis
• Pulse Contour Analysis
• Esophageal doppler
• Echocardiography (both TTE and TEE)

I have personally only used pulse-contour analysis technologies to obtain this measurement.

When was SVV first described in the literature?

The first study to describe stroke volume variation (SVV) that I found was back in 2002. That article was titled “Stroke volume variations for Assessment of cardiac responsiveness to volume loading in mechanically ventilated patients after cardiac surgery.” Here, they found that SVV was helpful in cardiac surgery patients. Its uses include the ability to “predict and continuously monitor effects of the volume administered as part of their hemodynamic management.”

Limitations of Stroke Volume Variation (SVV):

– needs to be on mechanical ventilation
– no cardiac arrhythmias
– tidal volume needs to be >8cc/kg of ideal body weight
– you need a fancy machine
– most devices need an arterial line
Part of the issue is that clinicians need to remember these limitations.

Stroke Volume Variation in Patients on Low Tidal Volumes

Stroke Volume Variation, also known as SVV, is a method to assess fluid responsiveness in critically ill patients.
Criteria to obtain an accurate stroke volume variation include that the patient needs to be on the vent and not spontaneously breathing.
They cannot have any cardiac arrhythmias.
They sometimes need an arterial line and always need a fancy device to measure the stroke volume variation.
If you have all your ducks in a row, using SVV is considered to be excellent, with an AUC of 0.84 based on a previous systematic review and meta-analysis.
This is using a threshold of >13% to be fluid responsive.
A caveat that was of utmost importance was that the patients should be set at a tidal volume at or greater than 8cc/kg.
I recently found a paper by Alvarado et al. that looked at numerous hemodynamic parameters to assess fluid responsiveness.
Using a threshold of 12, the authors found an AUC of 0.9 for patients in patients with low tidal volume.
Does this mean that we can throw out the tidal volume parameter?
What do you think in the comments.

Does SVV work on patients who are spontaneous breathing?

Stroke Volume Variation doesn’t work in patients who are spontaneously breathing. I have seen clinicians who are well respected where they’ve said that it works “to trend,” but I am not a fan of shortcuts. The AUC in those patients is 0.53 per the linked Zhang paper. Perner et al. found that this does not work with an AUROC of only 0.51. That means a coin flip is as accurate as SVV in determining fluid responsiveness.

Putting it all together

All in all, it’s another tool in the tool belt. We need as many as we can. I prefer this value to show up on a screen over numerous other parameters that require me to be at the bedside at x-minute intervals.

If you want to learn about pulse pressure variation, CLICK HERE.

Citations:

Reuter DA, Felbinger TW, Schmidt C, Kilger E, Goedje O, Lamm P, Goetz AE. Stroke volume variations for assessment of cardiac responsiveness to volume loading in mechanically ventilated patients after cardiac surgery. Intensive Care Med. 2002 Apr;28(4):392-8. doi: 10.1007/s00134-002-1211-z. Epub 2002 Mar 20. PMID: 11967591.
Link to NOT FREE Article

Zhang Z, Lu B, Sheng X, Jin N. Accuracy of stroke volume variation in predicting fluid responsiveness: a systematic review and meta-analysis. J Anesth. 2011 Dec;25(6):904-16. doi: 10.1007/s00540-011-1217-1. Epub 2011 Sep 4. PMID: 21892779.
Link to Abstract

Perner A, Faber T. Stroke volume variation does not predict fluid responsiveness in patients with septic shock on pressure support ventilation. Acta Anaesthesiol Scand. 2006 Oct;50(9):1068-73. doi: 10.1111/j.1399-6576.2006.01120.x. Epub 2006 Aug 25. PMID: 16939480.
Link to Article
Link to FULL FREE PDF

Vignon P, Repessé X, Bégot E, Léger J, Jacob C, Bouferrache K, Slama M, Prat G, Vieillard-Baron A. Comparison of Echocardiographic Indices Used to Predict Fluid Responsiveness in Ventilated Patients. Am J Respir Crit Care Med. 2017 Apr 15;195(8):1022-1032. doi: 10.1164/rccm.201604-0844OC. PMID: 27653798.
Link to Article
Link to FULL FREE PDF

Hofer CK, Cannesson M. Monitoring fluid responsiveness. Acta Anaesthesiol Taiwan. 2011 Jun;49(2):59-65. doi: 10.1016/j.aat.2011.05.001. Epub 2011 Jun 24. PMID: 21729812.
Link to Article
Link to FULL FREE PDF

Alvarado Sánchez JI, Caicedo Ruiz JD, Diaztagle Fernández JJ, Amaya Zuñiga WF, Ospina-Tascón GA, Cruz Martínez LE. Predictors of fluid responsiveness in critically ill patients mechanically ventilated at low tidal volumes: systematic review and meta-analysis. Ann Intensive Care. 2021 Feb 8;11(1):28. doi: 10.1186/s13613-021-00817-5. PMID: 33555488; PMCID: PMC7870741.
Link to Article
Link to FULL FREE PDF

Other Resources:
Jon-Emile Kenny, MD wrote a great review. Always love his work. SVV.
Alex Yartsev wrote a great review on his page “Deranged Physiology”

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