OACCM Advisor's Blog #5 - September 2012 - William T. McGee, M.D., M.H.A.

Defining the Volume Prescription in the Critically Ill.

The blog will follow my part of a symposium presented at the Society of Critical Care Medicine’s annual meeting this past February entitled “The Physiologic Optimization Program: Physiology Based Fluid Management”. This talk provides a conceptual framework for "the volume prescription."  The majority of data for my presentation addresses the perioperative manipulation of fluids for high risk patients. Importantly, however, the volume prescription requires close attention for the duration of the vulnerable period for patients which extends beyond the operating room and into the ICU.

Also you will find on the OACCM website an article my colleagues, Dr. Mailloux Jennifer Federici, and Dr. Freda recently published in the Journal of Nephrology that critically looks at the volume prescription in ICU patients receiving renal replacement therapy. Specifically, this article addresses physiologic volume management with discrete goals based on functional hemodynamics to manage the deresuscitation phase of critical illness.  The term DEVOLVE is introduced to describe deresuscitation of the volume overloaded patient, which is now seen as an increasingly important part of management of the critically ill.  There is emerging data beyond acute lung injury/ARDS (see FACTT N Engl J Med 2006; 354:2213-2224 ) http://www.ardsnet.org/studies/factt/study_synopsis that emphasizes the importance of the volume prescription for the critically ill.

The blog will now roughly follow the slides that you can view on the website:

This talk emphasizes not only the importance of using physiology to manage volume but also mentions the multitude of technologies that are available to accomplish this goal in 2012.  Local familiarity and expertise with these technologies should determine their use in your particular setting.  My only plea is that physiology be applied to the volume prescription.  This talk outlines why that is important. 

We know the issues around hemodynamic monitoring especially for the critically ill have been controversial even before the publication of Connors’ seminal article (JAMA 1996 Sept 18; 276(11):889-97) http://www.ncbi.nlm.nih.gov/pubmed/8782638 as part of the SUPPORT study back in 1996.  I do believe, however, that although a treatment protocol showing improved outcomes related to physiologic management will ultimately be the most important aspect encouraging broad application of these technologies; at a minimum volume management should be based  on physiology that involves no significant increased risk to the patient.  Unlike the PA catheter with its associated risk, the acquisition of hemodynamic data today is simpler and safer for patients.

I begin my presentation with an article published on October 27, 1994, the lead article in the New England Journal of Medicine entitled "Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso injuries” Bickell, et al. http://www.nejm.org/doi/full/10.1056/NEJM199410273311701  which examined the outcomes of delaying fluid resuscitation for a group of patients in whom rapid restoration of circulating blood volume was thought to be critically important.  More on this later.

The viewpoint article in Critical Care published this past year, entitled "A critique of fluid bolus resuscitation in severe sepsis” http://ccforum.com/content/16/1/302/abstract, Andrew Hilton and Rinaldo Bellomo authors, emphasizes the point that precise titration of volume in severe sepsis is better than current standard of care.

Intellectually when giving volume a simple question should be addressed, and that is: What is the impact on cardiac performance?  The answer to this question requires a cardiac performance measure as ultimately oxygen delivery is what we can control regarding organ perfusion and function.  Increasingly data shows that if there is no perfusion benefit to volume therapy excessive volume is likely to be harmful to the patient.

The beauty of using the data pair stroke volume and stroke volume variation is that it individualizes the Starling relationship and allows titrated therapy to achieve the maximum benefit from increasing preload without volume overload.  Simply stated it provides a goal for volume therapy and both interestingly and importantly allows for deresuscitation to proceed using the same targeted approach. (Slide 10)

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Another benefit beyond goal directed therapy, especially considering the multiple practitioners that may be involved in an individual patient’s care is standardization which, by itself, is likely to improve outcomes.

The physiologic optimization program which has been in use now in some form since 2005 provides a standard approach to the often perplexing questions around hypotension and oliguria.  For those patients who are not volume responsive (the right side of the algorithm; #1,2,3 Slide 13),

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the clinical impression along with the indexed stroke volume guides therapy.  I like using the indexed stroke volume to provide further standardization across patient body types being aware of two limitations.  One is that there is a broad range of normal so essentially we need to assess this on an individual basis.  Second the program has been designed to answer a clinical question.  We know much more about our patients than simply this data pair.  Practically speaking the physiologic optimization program is an aid to clinical decision making and is not meant to be used in isolation.

The focus for the remainder of this blog is the use of the Frank-Starling curve to remove volume during the post resuscitation phase of critical illness.  As you may imagine this application certainly is possible in any volume overloaded patient.  Assessment of an individualized Frank-Starling curve has not only simplified volume removal, but provides physiologic assurance that volume removal has not negatively impacted cardiac output and oxygen delivery.

This represents a significant advance in clinical critical care medicine!

The trauma/motor vehicle crash case presented in the following slides represents the use of the physiologic optimization program for both resuscitation of blood loss from traumatic injury and then volume removal utilizing the Frank - Starling mechanism to remove the excess fluid that was given during initial life-saving resuscitation.

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 If we illustrate this on the algorithm shown in Slide 18, we see on the left-hand side of the algorithm during the initial severe hemorrhagic shock with elevated SVV volume was given in significant amounts.  Ultimately, however, we overshot and the stroke index ultimately was supraphysiologic at 66 cc/bt/m2 and two courses of option now were undertaken.  Further IV fluid therapy was stopped and for this patient with acute lung injury diuretics were given.  The concept of goal-directed deresuscitation can now be practiced with great confidence.

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The slide with multiple Frank-Starling curves further emphasizes the ability to individualize patients based on their own physiology.  The role of clinical judgment in determining what an appropriate cardiac output should be relative to the clinical situation is especially important for patients with wet lungs.

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Liberal volume therapy has been the mainstay of caring for the critically ill.  Throughout my career over the past 25 years, the concept that IV fluids are harmless encourages this thinking.  Intellectually, however, it is clear that the only benefit of fluids for the majority of our patients are improved cardiac performance as measured by the stroke volume.

Table 5 shows the outcome for the experiment in penetrating torso injuries according to treatment group.  The delayed resuscitation group who received the least fluids had less blood loss, shorter hospital stays and better survival.  The next slide is composite data from the FACTT trial revealing no mortality difference based on fluid strategy; liberal with a high CVP or wedge pressure target or conservative with a low CVP or wedge pressure target. However, importantly a two day difference in ventilation, two days less in the ICU and two days less in the hospital was achieved with furosemide and  a conservative fluid strategy; targeting a lower CVP < 4 mmHg or a pulmonary capillary wedge pressure < 9 mmHg.  Furthermore, this approach which in my reading of the literature represents the largest study ever done to examine the effects of Lasix on a population with severe sepsis and acute lung injury, there was no increase in acute kidney injury. This occurred despite a major difference in volume management of approximately a liter a day for the first seven days in the study.  The following slide reiterates the association between fluid balance and mortality

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The "Mortality after fluid bolus in African children with severe infection” published in the New England Journal of Medicine, June 30th 2011 was one of the most interesting studies that I reviewed last year.  Although management of children in Africa is significantly different than how we would manage children with severe infection in United States and the study has been criticized because of this, I believe it is well designed to show the impact of excess fluid therapy on outcome simply because other than antimicrobial therapy and volume therapy there were few if any higher technical interventions on these children, emphasizing the importance of appropriate volume therapy.  Fluid boluses increased 48-hour mortality significantly in critically ill children with impaired perfusion.  I strongly recommend reading this article and the accompanying editorial to all of you.  http://www.nejm.org/doi/full/10.1056/NEJMoa1101549

The impact of fluid balance was also evaluated in regards to patients with acute renal failure and again fluid balance was associated with increased mortality.

I think the data is clear that both inadequate and excessive fluid administration have great potential to negatively impact patient outcome.

The following observational study "Importance of fluid management in acute lung injury secondary to septic shock” is an observational study published in Chest in 2009 http://www.ncbi.nlm.nih.gov/pubmed/19318675.   It highlights the importance of getting the fluid prescription right both during the resuscitation phase, which they term AIFR for aggressive initial fluid resuscitation, and in the deresuscitation phase, which they term CLFM conservative late fluid management.  The following slide exams multivariate analysis of the independent risk factors for mortality.  If the patient was not resuscitated aggressively upfront they were five times as likely to die.  Just as important if volume was not removed after the initial resuscitation phase; conservative late fluid management, CLFM, not achieved, the patient was six times as likely to die.  I included several slides from this manuscript that was published in Chest to emphasize the importance of fluid management on mortality.

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Finally, our paper which is now available on the website addresses the application of the Frank-Starling mechanism on deresuscitation in patients with renal failure in the ICU.  http://www.ncbi.nlm.nih.gov/pubmed/22241635
Our study looked at goal-directed deresuscitation using renal replacement therapy in critically ill patients.  The concept for us is this allows confidence with the volume prescription, eliminates guesswork, and finally provides a standard for what is often an arbitrary decision regarding fluid management.

The conclusions of our study in Slide 37, show that if the SVV was less than 13% volume was able to be removed.  Similarly, if the stroke volume index was greater than 35cc/bt/m2 thosepatients were also able to undergo volume removal

 

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Clearly, similar targets can be applied in a population of patients without renal failure using diuretic therapy.  Slide 39 superimposes the data from Murphy and Schramm on volume management and acute lung injury secondary to septic shock on the physiologic optimization program for the critically ill.


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We have delivered hemodynamic management using a protocol based on physiology.  Hopefully I have presented enough data to make the point that therapy based on physiology is better than guessing and that volume management has great potential to impact patient outcome.

I hope you have found this description of goal-directed volume therapy, "the volume prescription” useful to your practice.  Please do not hesitate to ask your questions of me through the website.

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January, 2012 - Blog # 4 - Dr. McGee on Hemodynamics

September , 2011 - Blog # 3 - Dr. McGee on Hemodynamics

June , 2011 - Blog # 2 - Dr. McGee on Hemodynamics

May , 2011 - Blog # 1 - Dr. McGee on Hemodynamics

William T. McGee, M.D., MHA, FCCP is Associate Professor of Medicine and Surgery at Tufts University School of Medicine, Boston, Massachusetts.  His interests are in ARDS, vascular access (pulmonary artery catheterization), sepsis, nutrition, and nosocomial pneumonia.  He has published > 67 papers, chapters and abstracts.  He is the principal investigator for clinical trials studying the efficacy and safety of rfPAF-AH for the prevention of ARDS in patients with severe sepsis.  He is a three-time recipient of Excellence in Teaching Award from Tufts University School of Medicine, the Society of Critical Care Medicine Internal Medicine Specialty Award for “Influence of Insurance Status on Pulmonary Artery Catheter Use” and The Presidential Citation Award from the Society of Critical Care Medicine for outstanding contribution to the Society.  He is a Director for the Fundamentals of Critical Care Support Course for the Society of Critical Care Medicine.  Dr. McGee is also a reviewer for several critical care journals. 

McGee