CLINICAL ISSUES Hypertonic Solutions: An Update

In the military setting, where longer transport times and logistical concerns present more difficult problems than in the civilian setting, smaller-volume resuscitation fluids are a necessity.1 In the past two decades, the answer to this reqirement has been the administration of hypertonic saline (HS) solutions with and without the addition of colloids. In 1999, the Committee on Fluid Resuscitation for Combat Casualties for the US Army recommended the use of HS for the treatment of combat casualties.2 However, the concepts behind this treatment strategy are by no means novel. Clinical use of hypertonic solutions dates back to 1926, when Silbert3 used 5 % saline to treat Burger’s disease. Moder-ately hypertonic solutions of 1.5 % to 3 % have been used to treat patients with burn shock and hypovolemia since the 1970s.4 Renewed interest in these solutions was not wide-spread, however, until 1980, when researchers in Saõ Paulo, Brazil, reported using 2400 mOsm HS to treat severe hemor-rhagic shock successfully.5,6 Numerous studies over the past two decades have established that HS infusions promote diuresis/natriuresis, augment cardiac output, increase cardiac contractility, and directly vasodilate the peripheral vasculature. Adding a colloid can transiently (depending on type added) expand plasma volume and can be used safely for resuscitation of patients with hypovolemia.7 Several experimental and clinical studies have investigated the efficacy, dosages, and infusion rates of different hyperosmotic solutions—primarily 7.5 % HS administered solely or in combination with dextran or hetastarch.8-10 The focus now is on 7.5 % HS, 7.5 % HS/6% dextran 70 (HSD), and 7.2 % or 7.5 % HS/6 % hetastarch (HHS). Although originally developed for hypovolemic resuscitation in the prehospital setting, these solutions have also been used to treat burns, sepsis, nontraumatic hemorrhages, and vascular Key Words: Fluid therapy, Hypertonic solutions, Review hypertonics. and cerebral injuries. This article reviews the mechanisms of action and clinical indications for the use of hypertonic solutions