It should be noted, however, that the benefits of early and aggressive fluid replacement in victims with ongoing hemorrhage, whether given in the prehospital setting or the ED, remain unproven. Many animal studies have shown that raising the blood pressure with either vasopressors or fluid also worsens mortality, sometimes dramatically.11 Such findings were recently validated in a prospective clinical study of hypotensive patients with penetrating torso injuries in which improved outcome was demonstrated for those whose fluid resuscitation was delayed until the start of operative intervention. 10 These studies indicate that resuscitation to normotension is harmful because it exacerbates continued hemorrhage and that some degree of "underresuscitation" may be beneficial. 12 Conversely, to purposefully withhold resuscitation as the patient exsanguinates is also wrong.
Both animal and human studies continue in an attempt to determine the ideal rate and volume of fluid administration as well as the appropriate therapeutic end point of resuscitation.13 The traditional end point of isotonic fluid resuscitation has been clinical assessment of the adequacy of tissue perfusion. In addition, the use of red cells was generally identified as a hemoglobin of 10 g/dL or a hematocrit of 30 percent as the "transfusion trigger." However, such a guideline is not reliable in an actively hemorrhaging patient, particularly in the setting of trauma. At the present time, the amount and type of volume expander used depends primarily on the clinical status of the patient and to a lesser extent on individual institutional preference. In most hospitals, isotonic crystalloid—either 0.9% NaCl [normal saline (NS)] or Ringer's lactate (RL)—is the agent of choice for the initial management of acute hemorrhage. Standard therapy of the hemodynamically unstable patient is rapid infusion of 20 to 40 mL/kg as fast as possible, typically over 10 to 20 min. Since, at best, only about 30% of infused isotonic crystalloid stays intravascular, blood volume restoration with NS or RL requires a volume approximately three times that of the lost blood (Tabie.27-3).14 An isotonic infusion of 30 mL/kg can be expected to expand blood volume by about 10 mL/kg, roughly one-seventh of the estimated blood volume of 70 mL/kg. Thus, if an adult patient continues to show signs of impaired perfusion after a total of 30 mL/kg (roughly 2 L), it is likely that blood loss exceeds 15 percent of the total blood volume.
Was this article helpful?