The debate surrounding resuscitation fluid is heating up. I previously blogged about a review in NEJM here. A similar review appeared in the World Journal of Critical Care Medicine and is available as free full text. Below are some key issues from that review.
Assessing the need for fluid and monitoring the response
Traditional metrics such as CVP have recently been called into question. Novel approaches such as pulse pressure variation and echocardiographic assessment of IVC diameter and its respiratory variation are believed to be superior but supported mainly by low level data. How do we know that once subject to rigorous outcome based trials they won't go the way of the PA catheter? On the other hand the article points out that there is some value in measurement of tissue perfusion end points such as lactate. So, although how to assess volume is controversial, volume assessment remains important. Good old fashioned bedside clinical assessment, perhaps guided by lactate measurements, may be as good as anything we can do. Individualization of therapy is more important than, as termed in the paper, “generic resuscitation endpoints.”
Crystalloid versus colloid
This debate remains unsettled. We lack strong evidence that colloid, which is more expensive, is any better than crystalloid. The recently published ALBIOS trial raised interest in the use of albumin in severe sepsis and septic shock. However, this was not a comparative study of resuscitation fluids and the results were mixed. For a balanced discussion of ALBIOS see here. Finally, keep in mind special situations in which albumin is specifically recommended such as hepatorenal syndrome and spontaneous bacterial peritonitis. The harm associated with starch products is well known and has been discussed previously.
The past couple of years have seen a rising concern over whether balanced electrolyte solutions should be used instead of normal saline. Balanced solutions have long had theoretical appeal. More recently data are trickling in suggesting that balanced solutions are associated with better outcomes. Though not strong enough to mandate practice change they do warrant consideration in the choice of crystalloid in various situations.
How much fluid?
Recent findings suggest that the answer is time dependent. Under resuscitation is a concern in the early hours. However, net positive fluid balance over a longer period appears harmful. Stated simply, front load then back off. The authors of the review take it a step further by suggesting a third phase of active fluid removal later in the course of illness.