Blood viscosity and red cell aggregation changes after hemodilution in vivo and in vitro. A comparison between different plasma substitutes.
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Biomedical subjects
Publications and source records attributed to E Haglind.
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Shock was induced in 60 dogs by exteriorization of the small intestine for three hours. The relative effectiveness of various hemodiluting agents on the microcirculation was measured as skeletal muscle capillary blood flow (QXe) and capillary permeability (P) surface area (S) for plasma (PSp), as calculated from the clearances of two locally injected isotopes, 133 Xenon and 131 Iodide. Skeletal muscle oxygen tension (Pm(2) was measured with a tissue PO2 electrode. During shock QZe decreased to 26%, PSp to 31% of the initial values, and PmO2 dropped from 51 to 18 mmHg. The degree of recovery from shock was assessed after reposition of the intestine and the infusion of different plasma substitutes (albumin, dextran 40, dextran 70, gelatin, ACD-plasma, and Ringer's acetate). Return of the intestine to the abdominal cavity did not in itself improve the shock condition. Dextran 40 and dextran 70 infusion increased QXe, PSp, and PmO2 to or above control levels, PSp to 60%, and QXe to 40% of the control values. Ringer's acetate gelatin, and ACD-plasma did not improve QXe but increased PSq to 62-67% of control values. Albumin and dextran increased PmO2 significantly in relation to no-fluid infusion. Only dextran 40 and dextran 70 increased both QXe and PSp significantly in relation to no -fluid infusion.
The aim of this study was to standardize a model allowing studies of mechanisms of importance for developing irreversible shock. The model should also be suitable for studying the effects of different modes of treatment. Graded obstruction of the intestine and its vascular supply in rats was induced with a hydrostatic pressure cuff. Three levels of obstruction pressure were used: 50, 100, and 120 cm water. Mortality increased from 0% in control groups to 75% in the highest pressure group. Increases in hematocrit occurred in all groups. Mucosal lesions, including total destruction of villi, were more severe in the two highest pressure groups, and the degree of mucosal lesion correlated with mortality. This shock model was developed to allow studies of factors of importance for survival. One such factor is the degree of mucosal lesion.
Shock was induced in sixty dogs by laparotomy, splenectomy and exteriorization of the small intestine for three hours. Resuscitation following different plasma substitutes was assessed by measuring hemodynamic parameters (mean arterial blood pressure, plasma volume, oxygen consumption, cardiac output and hematocrit). To justify a comparison, the colloids (albumin, ACD-plasma, dextran 40, dextran 70, gelatine) were given at the same concentration and dose (3.5 % solutions in saline at a dose of 1.5 g/kg or 43 ml/kg). Ringer's acetate was given in a three times larger volume (129 ml/kg). After reposition of the intestine, the infusion was given over a 20 minute period. During shock hemoconcentration developed, increasing from 50 to 59 % in hematocrit; mean arterial blood pressure dropped from 144 to 95 mm Hg; plasma volume decreased to 67 %; total body oxygen consumption decreased to 59 % and cardiac output to 21 % of initial values. Reposition of the intestine did not in itself improve these values. Ringer's acetate was effective up to about 30 minutes after infusion but did not differ from no infusion at four hours. Gelatine and ACD-Plasma had a similar effect up to two hours. Albumin, dextran 40 and dextran 70 increased and maintained plasma volume and oxygen consumption at preexperimental levels for up to at least four hours. It is concluded that a single infusion of albumin, dextran 40 or dextran 70 is superior to ACD-plasma gelatine or Ringer's acetate in restoring and maintaining oxygen consumption and hemodynamic functions, when given in comparable doses and volumes.
This experimental shock model was well defined by the marked decrease in total body oxygen consumption, muscle PO2 and diffusion capacity during shock. Infusion of large amounts of electrolyte solution did not lead to a restoration of muscle oxygen tension after 1-4 hours. Dextran 40 infusion however restored both local PO2 and blood flow in the muscle as well as total body oxygen consumption.