Fluids

A patient with a respiratory rate of ≥30 breaths per minute, or a pulse of greater than 100 beats per minute or one that has a barely palpable pulse will require placement of an intravenous cannula and administration of intravenous fluids. Isotonic saline is commonly recommended initially for most patients,⁴ whereas Ringer’s lactate is recommended for patients who have sustained thermal injury.⁵ The goal is to maintain intravascular volume, cardiac output, and tissue perfusion until further evaluation and treatment can be undertaken. The disadvantage of isotonic saline is that it has a relatively large amount of chloride compared to that contained in Ringer’s lactate, which may worsen a pre-existing metabolic acidosis. The disadvantage of Ringer’s lactate, on the other hand, is that the small amount of K⁺ it contains may cause fatal hyperkalemia, even in patients with a crush injury sustained in an earthquake or explosion who do not have acute kidney injury (AKI).⁶ The goal during fluid resuscitation is to maintain blood pressure and urine output. However, excessive fluid administration can create as many problems as under-resuscitation, including abdominal compartment syndrome, which may worsen AKI.

Route of Administration

Those who practice in high-income countries are accustomed to resuscitating patients with intravenous fluids. However, following a disaster, in an austere environment intravenous cannulas and sterilized intravenous fluids may not be readily available. In 1950, the Surgical Study Section of the National Institutes of Health recommended that “the use of an oral saline solution is adopted as standard procedure in the treatment of shock due to burns and other serious injuries in the event of a large scale civilian catastrophe.”⁷ The solution that was recommended was Myers solution: a hypotonic (160 mOsm) solution containing 85 mEq of Na⁺ that is buffered with either bicarbonate or citrate. These recommendations are relatively easy to implement in a timely fashion and their application may result in improved outcome, at least from AKI in patients who have sustained crush injury⁸ or thermal injury.⁹

Other alternatives to intravenous resuscitation must be considered, e.g. when dealing with patients with highly contagious and lethal (Class A bioweapon) infectious diseases. In the 2014–2016 Ebola viral disease (EVD) pandemic, treatment was largely supportive and quite basic. Because of EVD’s effects on the gastrointestinal system, enteral resuscitation was not an option, and the placement of intravenous cannulas by personnel wearing PPE (personal protective equipment) in patients whose extremities were edematous presented a major challenge. In such circumstances the placement of intraosseous cannulas for fluid resuscitation is more readily achieved and can be lifesaving.¹⁰

Crush Injuries

In the December 1988 earthquake in Armenia there were 25 000 fatalities; there were more than 900 severely injured patients of whom 900 had AKI, one-third of whom required dialysis.¹¹ AKI is the leading cause of delayed mortality following an earthquake (the majority of patients die acutely from head or thoracic crush injury in collapsed buildings at the time of the event). AKI and death can be avoided by the timely administration of fluid.¹² Saline is recommended as it is efficacious and associated with few side effects. Sodium bicarbonate added to 0.5 N saline attenuates the deposition of uric acid and myoglobin in the renal tubules, decreases the incidence of hyperkalemia, and corrects metabolic acidosis, but may not be available in an austere environment.⁴ As discussed previously, solutions containing even small amounts of K⁺ should be avoided. The administration of mannitol to treat the rhabdomyolysis associated with crush injury is somewhat controversial. Mannitol is believed to be therapeutic because of its diuretic, vasodilating, and antioxidant properties. Mannitol increases intravascular volume, prevents deposition of myoglobin and uric acid in renal tubules, decreases intercompartmental pressures and muscle edema, and decreases the incidence of compartment syndrome. Mannitol is not without risk though, as it may worsen congestive heart failure in at-risk patients, and is associated with nephrotoxicity per se. The decision to use mannitol, if available, must be made on a case-by-case basis, under close supervision with appropriate monitoring, which may be difficult, depending on the extent and severity of the mass casualty event. If mannitol is used, a small dose is recommended initially and continued only if there is a satisfactory diuretic response.