Fluid resuscitation in controlled and uncontrolled hemorrhage

Background: For many years, early intravenous fluid resuscitation has been widely accepted as an appropriate treatment of the trauma patient at the scene of the injury, regardless of the type of trauma and hemorrhage. The present Thesis describes the effects of fluid resuscitation on the hemodynamics in the presence of a limited controlled hemorraghe and also particularly in the situation when the bleeding is uncontrolled. Methods: I: Eighteen healthy male volunteers were subjected to a 900-mL withdrawal of blood which was replaced with an i.v. infusion of 900 mL of Ringer's solution (n=12) or albumin 5% (n=6); further on, eight of the volunteers receiving Ringer's solution received another 900 mL. II: Thirty-two anesthetized pigs were prepared in such a way as to induce a standardized intra-abdominal vascular aortic lesion in order to evaluate, the spontaneous changes in hemodynamics during and early on after hemorrhage. III. Thirty-two anesthetized pigs were prepared as in study 11 but randomized to receive at 10 min after starting, either no i.v fluid resuscitation or fluid infusion with Ringer's solution in the ratio of 1: 1, 2:1 or 3:1 to the expected blood loss. As in the animal studies IV-VI, the follow-up time was 120 min. IV. Eight anesthetized pigs were prepared as in study III but they received Ringer's solution in the ratio of 3:1 between 10 and 30 min into the study. V. Sixteen anesthetized pigs were prepared as in studies II-IV but were randomized to receive at 10 min after starting, a bolus injection of hypertonic saline/dextran (HSD) amounting to 4 mL/kg and 2.65 mL/kg, respectively. VI. Eight anesthetized pigs were prepared as previously described but also fixed in a missile wound model in order to inflict a standardized high-energy gunshot wound on the thigh in addition to the intraabdominal hemorrhage. Results: I: Withdrawal of 900 mL of blood decreased cardiac output and splanchnic and renal blood flow rates by 16-20%. Autotransfusion of fluid from the extravascular to the intravascular space was indicated by hemodilution. The hemodynamics were better restored with 900 mL of albumin 5% than with 900 mL of Ringees solution. II. The short-term changes in blood flow rates closely follow a simple monoexponential function which makes it possible to express them as half-times (T1/2). Bleeding stops spontaneously after about 3 min. III. During the first 40 min after hemorrhage, compared to baseline, the blood flow rates in the aorta distal to the vascular lesion were 39% (no fluid), 41% (1:1), 56% (2:1), and 56% (3:1), respectively. Rebleeding occurred only when Ringer's solution was infused in the ratio of 2:1 and 3:1. Survival was highest with the 1:1 and 2:1 infusion programs. IV. During the infusion of Ringer's solution between 10 and 30 min after hemorrhage, blood flows, as well as oxygen consumption increased transiently although minor rebleeding episodes during the infusion were observed in three animals. Four animals died in shock. V. The injection of HSD in a bolus injection at 10 min was followed by a prompt increase in all blood flow rates as well as blood pressures. This was closely followed by a rebleeding episode in 13 out of 16 animals and six even had a second episode of rebleeding. Five animals in each treatment group died before the end of the study. VI. The high- energy gunshot wound to the thigh induced instant depressant effects on central hemodynamics which reduced the intra-abdominal bleeding when the aortic vascular lesion was induced. After HSD was injected at 10 min, rebleeding occurred in five animals but the additional blood loss was less than that observed in study V. Conclusions: A controlled hemorrhage of approximately I liter is efficiently compensated for by normal physiological defense mechanisms and rarely needs to be replaced early . In a low-energy trauma with uncontrolled hemorrhage, rebleeding is a serious advent which may occur when fluid resuscitation with Ringer's solution is given in the ratio of 2:1 or 3:1 to the expected blood loss, as well as when HSD is given in a bolus injection. When the trauma is more complicated, hemodynamic mechanisms change, but the risk of rebleeding remains if bleeding is not controlled