January 16, 2013 | Leave a Comment
Guest Lecture Series by Dr. Andrew Shaw of Duke University on January 16, 2013.
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Dr. Shaw begins his talk with a brief history of the dilemma surrounding the optimal fluid resuscitation strategy. Since 1832 (eighteen thirty two) physicians have been struggling with the type and amount of fluid that should be administered for resuscitative efforts. Back then, it was believed that too much fluid administration was a bad thing, but studies did not show negative effects of over-resuscitation. This lack of negative effects was probably due to the study designs, in that the risk of adverse effects from over-resuscitation occurs weeks to months later, rather than days later.
Studies have now been showing that all organ systems are adversely affected by over-resuscitation. Most of these adverse effects occur well later than the end-point of previous investigations. A 2010 Nature Review Nephrology meta-analysis highlighted a number of studies that indicate damage to different organ systems with over-resuscitation. In fact, Payne et al (Crit Care 2008) showed a 20% increase in mortality each day that a patient in acute renal failure is positive by 1 liter!
Today’s lecture, however, was not about the optimal volume of fluid to be given, or how to determine the amount of volume needed. Rather, the talk was focused primary on the type of fluid to be given.
Recent data suggest that it is chloride that is associated with worsening survival rates and higher incidences of acute renal failure requiring renal replacement therapy (RRT). In a retrospective study by Dr. Shaw (Annals of Surgery 2012), intra-abdominal surgical patients receiving 0.9% saline versus plasma-lyte (considered a balanced solution) required more PRBC transfusions and had a higher rate of RRT. Indeed Yunos et al (JAMA 2012) showed that ICU patients receiving a chloride-restrictive solution (like Ringer Lactate or plasma-lyte) had a lower risk of developing acute renal failure based on the RIFLE and AKIN criteria.
Shaw then turned his attention to the debate between crystalloids and colloids. Although colloids are not commonly prescribed in the US, it turns out that even today, the most common resuscitative fluid administered worldwide are colloids (specifically, hydroxyethyl starch – HES). In the SAFE-TRIPS cross-sectional study of 391 ICUs across 25 nations (~ 2000 patients), the choice of resuscitative fluid is geographic, despite no evidence that colloids decrease mortality. In the SAFE trial (NEJM 2004), there was no difference in mortality between saline administration and albumin administration. While most physicians view these results in a positive way (i.e., albumin is just as good as saline), Shaw views these results as negative (i.e., albumin and saline are equally as bad to solutions considered “more balanced”). This perspective is supported by data from the FEAST Trial (NEJM 2011) that was halted early because of worse outcomes (45% increase risk of death) in children receiving both saline or albumin compared to receiving no bolus fluid resuscitation at all (OR 1.45, 95% CI 1.13-1.86).
Finally, Shaw turns his attention to starch — specifically hydroxyethyl starch (HES), hetastarch, and pentastarch. In the VISEP trial (NEJM 2008) there was a dose-dependent increase in need for dialysis and risk for death in the pentastarch arm (versus the Ringer Lactate arm) at 90 days. The 6 S trial (NEJM 2012) showed a decrease in survival as early as 3 weeks with the use of HES versus Ringer Acetate.
Take home points:
— don’t use colloids over crystalloids, especially albumin and starch-based solutions. there simply isn’t enough data in favor of albumin or starch-solutions over crystalloids
— 0.9% saline has been the preferred resuscitative fluid for decades, but may be falling out of favor given its increase risk for developing dialysis-dependent ARF compared to “balanced solutions” (those with lower chlorides)
— it’s still not clear if solutions that are low in chloride are beneficial because of the low chloride, or because they contain other solutes not found in 0.9% saline (like Mg, acetate, gluconate) or because of lower sodium concentrations.
— we still don’t have a dose-dependent curve that illustrates the risk of ARF (requiring dialysis) with differing concentrations of chloride in a resuscitative solution