In Podcast 64, Paul Marik and I discussed the concept of Fluid Responsiveness, and then we had the amazing Jean-Francois Lanctot discussing his four-part assessment with ultrasound to determine fluid use in sepsis. After that talk, I definitely felt I needed to discuss some of these issues further. If you have not listened to those two podcasts, it may be beneficial to go back before listening to this one.

and what has come to me is that perhaps we have been conflating two concepts:

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Can the RV take it?

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Can the LV use it?

Perhaps the problem we have been having is that we are trying to blend these two questions into 1. Let's use that as our path to discuss this morass of volume-responsiveness

Fluid Challenge or PLR with CO measurements

Stress the System with PLR or Fluid Challenge

Passive Leg Raise

Worth mentioning, though it should be obvious, PLR demonstrates how ridiculous the practice of Trendelenberg Position for resuscitation

Fluid Challenge

500 ml crystalloid or colloid

10-Second Mini-Fluid Challenge

50 ml bolus over 10 seconds through a central line (Critical Care 2014;18:R108) change in VTI measured immediately afterwards

Then Measure the Response

Can Changes in MAP Predict Fluid Responsiveness?

[cite source='pubmed']22278593[/cite], [cite]20111858[/cite], [cite]22464162[/cite]

Most recent analysis states changes in MAP don't predict CI increase from fluid load in septic shock (Intensive Care Med (2012) 38:422–428)

The Cardiac Output Monitors

Marik's Comprehensive Review Article

and my buddy Seth Manoach wrote a nice review as well [cite source='pubmed']22537573[/cite]

NICOM - Bioreactance

* Marik studied 34 patients in the ICU with PLR, NICOM, SVV, and Carotid Flow (The use of NICOM (Bioreactance) and Carotid Doppler to determine volume responsiveness and blood flow redistribution following passive leg raising in hemodynamically unstable patients (Chest 2012 Marik et al.)

* Big validation study showed good accuracy (Intensive Care Med (2007) 33:1191–1194)

* There were a couple of small studies indicating inaccuracy, but when I looked into these--the authors may have had some conflicts

USCOM - Aorta Ultrasound

* Anaesthesia. 2012 Nov;67(11):1266-71.

PiCCO

* PCA + thermodilution

Pulse Contour Analysis Alone

* Bunch of studies keep going back and forth in the lit. I'm not sure if these track changes in afterload. They don't accurately track pressors/inopressors (Anesth Analg. 2011 Oct;113(4):751-7.)

ETCO2

* A PLR-induced increase in EtCO2 >5 % predicted a fluid induced increase in CI >15 % with sensitivity of 71 % (95 % confidence interval: 48–89 %) and specificity of 100 (82–100) %. (Intensive Care Med (2013) 39:93–100)

* Passive leg raise to etco2 (CCM 2014;42:1585)

Carotid and Brachial Artery Analyses

Search for the evidence on pubmed, it is emerging now

LVOT velocity time integral (VTI)

* Accurate in the hands of experts--kind of annoying to obtain