ORIGINAL ARTICLE Cell Impermeant-based Low-volume Resuscitation in Hemorrhagic Shock A Biological Basis for Injury Involving Cell Swelling Dan Parrish, MD, ∗ Susanne L. Lindell, BSN, ∗ Heather Reichstetter, LVT, ∗ Michel Aboutanos, MD, ∗ and Martin J. Mangino, PhD ∗ †‡ Objective: To determine the role of cell swelling in severe hemorrhagic shock and resuscitation injury. Background: Circulatory shock induces the loss of energy-dependent volume control mechanisms. As water enters ischemic cells, they swell, die, and compress nearby vascular structures, which further aggravates ischemia by reducing local microcirculatory flow and oxygenation. Loading the interstitial space with cell impermeant molecules prevents water movement into the cell by passive biophysical osmotic effects, which prevents swelling injury and no-reflow. Methods: Adult rats were hemorrhaged to a pressure of 30 to 35 mmHg, held there until the plasma lactate reached 10 mM, and given a low-volume resus- citation (LVR) (10%–20% blood volume) with saline or various cell imper- meants (sorbitol, raffinose, trehalose, gluconate, and polyethylene glycol-20k (PEG-20k). When lactate again reached 10 mM after LVR, full resuscitation was started with crystalloid and red cells. One hour after full resuscitation, the rats were euthanized. Capillary blood flow was measured by the colored microsphere technique. Results: Impermeants prevented ischemia-induced cell swelling in liver tis- sue and dramatically improved LVR outcomes in shocked rats. Small cell impermeants and PEG-20k in LVR solutions increased tolerance to the low flow state by two and fivefold, respectively, normalized arterial pressure dur- ing LVR, and lowered plasma lactate after full resuscitation, relative to saline. This was accompanied by higher capillary blood flow with cell impermeants. Conclusions: Ischemia-induced lethal cell swelling during hemorrhagic shock is a key mediator of resuscitation injury, which can be prevented by cell impermeants in low-volume resuscitation solutions. Keywords: gluconate, Ischemia, osmotic effects, polyethylene glycol, resus- citation (Ann Surg 2015;00:1–8) D eaths due to injury in the United States reached more than 171,000 and costs more than $400 billion a year in health care costs and lost productivity in 2010. 1 Deaths from trauma are the num- ber 1 cause of death for people younger than 44 years in the United States and the third leading cause of death overall for all age groups. Trauma accounts for about 30% of all life years lost in the United From the Departments of ∗ Surgery, †Emergency Medicine, and ‡Physiology and Biophysics, Division of Acute Care Surgery, Virginia Commonwealth Univer- sity, Medical College of Virginia Campus, Richmond, VA. Disclosure: Supported by grants from the National Institutes of Health R01 DK087737 and the Department of Defense W81XWH-12-1-0599 to Dr Mangino. There were no conflicts of interest to declare. Reprints: Martin J. Mangino, PhD, Virginia Commonwealth University, Medi- cal College of Virginia Campus, Department of Surgery, Division of Acute Care Surgery, 1101 E. Marshall Street, Richmond, VA 23298. E-mail: mjmangino@vcu.edu. Copyright C  2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0003-4932/15/00000-0001 DOI: 10.1097/SLA.0000000000001049 States, compared to cancer (16%), heart disease (12%), and human immunodeficiency virus (2%). 2 For all traumatic injuries, hemor- rhagic shock is responsible for more than 35% of prehospital deaths and more than 40% of all deaths within the first 24 hours. This is sec- ond only to trauma deaths induced by severe central nervous system injury. 3 Finally, hemorrhagic hypotension exposes the patient to im- mediate complications of life-threatening infections, coagulopathies, and multiple organ failure. 4,5 Early resuscitation strategies include the use of low volumes of intravenous blood products to increase oxygen delivery and to re- place lost coagulation and clotting factors (coagulation proteins and platelets). Although this approach is fine for hospital emergency de- partments, it is not currently practical in prehospital settings where early intervention may be the key to preventing future complications following more definitive resuscitation. Crystalloids are available for prehospital use because they can be safely transported and stored but they are generally limited in their effectiveness. Attempts to modify basic intravenous crystalloids for prehospital resuscitation by adding hypertonic NaCl or starch (Hextend) as a volume expander have had disappointing results. 6,7 The future use of effective spray dried blood products will be a valuable tool in prehospital settings because they replace chemical coagulation precursors and factors. The use of fresh frozen plasma in the field, which is currently being tested at many centers, will also be useful but it too is limited by the need for refrig- eration. There remains a need for a better crystalloid to resuscitate patients with severe hemorrhagic shock, especially in a prehospital setting. The successful design of such a solution is highly dependent on understanding the pathophysiological mechanisms that lead to in- jury during hemorrhagic hypotension and subsequent resuscitation. The optimal solution will likely be an effective new stable crystalloid that targets these mechanisms used together with reconstituted dried plasma products for the replacement and reconstitution of coagulation potential. The predominant root mechanism of injury in hemorrhagic shock is energy failure. Although global ischemia and reperfusion in- jury are causally based at many levels, they all arise from changes that occur when the cell energetics drops because of a loss of adequate mi- crovascular oxygen transport and subsequent loss of aerobically pro- duced high-energy adenine nucleotides. 8–10 One mechanism of cell, tissue, and organ injury is cell swelling that occurs from the loss of adenosine triphosphate (ATP)-dependent cell volume regulatory con- trol mechanisms. In most cells, the single highest energy-consuming process is the running of the Na/K ATPase pumps in the cell mem- brane. These pumps actively transport sodium ions out of the cell to maintain membrane potentials and to run numerous Na + -dependent facilitated membrane transport processes such as calcium, glucose, amino acids, and organic cation transporters. In the absence of ATP to run those pumps, as occurs in ischemia after hemorrhagic shock, the Na/K ATPase turns off and sodium enters the cell as it runs back down its electrochemical gradient. The elevated intracellular sodium futilely stimulates the sodium pump that cannot run because of loss Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Annals of Surgery  Volume 00, Number 00, 2015 www.annalsofsurgery.com | 1