Annals of clinical research
-
This is a review article of the debated massive use of balance electrolyte solutions in the replacement of blood loss. We cannot directly apply the results and conclusions of American reviews on this subject as there are significant differences between USA and Finland in the use and availability of alternative fluids. Electrolyte solutions pass freely across the capillary membrane and are distributed in the extracellular compartment and as such poorly restore and maintain blood volume. ⋯ In blood loss replacement electrolyte solutions without dextrose are preferred. The minimal amounts of potassium in balanced electrolyte solutions is of no practical value. Even though crystalloid solutions can be tolerated in massive amounts, marked blood loss is replaced more physiologically and effectively using natural or artificial colloids in iso-oncotic concentrations together with red cell concentrates and fresh blood.
-
Oxygen transport and tissue oxygenation were investigated in twelve patients undergoing coronary bypass surgery under normovolemic moderate and extreme hemodilution. Moderate hemodilution, that was carried out after induction of anesthesia, decreased the mean hematocrit from 0.43 to 0.33. Concurrently, the cardiac index and the left ventricular filling pressure increased slightly whereas the systemic oxygen transport declined by 20%. ⋯ In general, total body oxygen consumption changed parallelly with the tissue oxygen tension. Lactate concentration in the mixed venous blood increased in the beginning of the extracorporeal circulation and remained rather stationary thereafter. All patients recovered normally without any perioperative myocardial infarctions.
-
With some amplifications, Starling's concept of the serum colloid osmotic or oncotic pressure as the determinant of fluid partition between the intravascular and the interstitial compartment has been confirmed by modern physiological research. The relationship between serum oncotic pressure and interstitial edema is non-linear, i.e. edema becomes progressively greater per mm decrease of the oncotic pressure. The intravascular volume effect of crystalloids is inseparable from interstitial edema, because it depends on an expansion of the interstitium which increases the hydrostatic pressure in that compartment sufficiently to compensate for a lowered capillary oncotic pressure. ⋯ In the lung, fluid exchange and distribution between the intravascular and the interstitial compartment is influenced by additional factors, and opinions on the use of colloids versus crystalloids continue to differ, particularly with respect to those circumstances where capillary permeability is presumably or demonstrably abnormal. However, the weight of the evidence still favours the concept that in patients with a much greater than respiratory distress syndromes much greater than, the serum oncotic pressure should at any rate not be permitted to drop below a certain critical level. A condensed review of these complex and as yet incompletely clarified problems is presented.
-
The most important determinants of the overall O2 delivery to tissues are the cardiac output and the arteriovenous O2 content difference. The latter is influenced mainly by the haemoglobin concentration, arterial haemoglobin O2 saturation and venous haemoglobin O2 saturation. Also the O2 tension has a minor contribution. ⋯ This effect allows greater O2 extraction from the blood by tissues. The changes in the haemoglobin O2 affinity are compensated in physiological conditions by changes in the cardiac output and in the venous O2 tension. If, however, in a situation of limited tissue O2 supply these mechanisms are used up or severely compromised the haemoglobin O2 affinity becomes an important determinant of the O2 delivery to tissues.
-
The present experiments compare the relative effectiveness of several plasma substitutes to reverse a standardized intestinal ischemic shock in dogs and rats. The colloids were given 3.5% solutions in a dose of 1.5 g/kg = 43 ml/kg for dogs and 2 g/kg = 57 ml/kg for rats.. Ringer's solution was given in a three times larger volume. ⋯ Colloids of 3.5 and 6% were more effective than a 10% colloid solution. These effects were related to the molecular weight distribution for colloids, the plasma volume expansion duration and their red blood cell aggregation properties. It is concluded that as single infusions albumin, dextran 40, and dextran 70 are superior to ACD plasma, gelatin, and Ringer's acetate in restoring hemodynamic and metabolic functions and in improving survival rate.