الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Anemia is almost universal in patients who spend more than few days in ICU and about half of ICU patients with anaemia are given one or more transfusion of concentrated erythrocytes to correct the problem. And in most cases, blood transfusions are given without documented evidence of need or benefit. The fear of anaemia is pervasive but unfounded because anaemia does not compromise tissue oxygenation as long as the intravascular volume (and hence cardiac output) is maintained.
There are two conditions that are recognized for favoring the development of anemia in ICU patients :
systemic inflammation .
repeated phlebotomy for laboratory studies.
The use of hemoglobin as transfusion trigger begin in 1942 with the recommendation that a hemoglobin of 10 hemoglobin be used as an indication for erythrocyte transfusions. This continues to be the most popular transfusion trigger today.
The lower hemoglobin level of 7g/dL is gaining popularity as a transfusion trigger for stable patients because of the compensatory changes in cardiac output and peripheral O2 extraction, progressive anemia will not impair tissue oxygenation until the hemoglobin and hematocrit reach dangerously low levels.
O2 extraction is better a transfusion trigger. O2 extraction is a sign of impending or actual tissue dysoxia. This means that an O2 extraction ,or ( SaO2 – SvO2 ) ,that is 50% or higher can be used as a transfusion trigger because it identifies the threshold for impaired tissue oxygenation . Oxygen extraction can be monitored continuously in ICU by using pulse oximetry (for arterial O2 saturation ) combined with venous oximetry (for venous O2 saturation ).
Complications are reported in 2 to 4 % of erythrocyte transfusion:
- Immune reactions
- Infections
- Transfuion errors
Some of these complications are a result of inherent properties of the blood products being transfused; others are a consequence of the storage of the red blood cells.
The use of epoetin alfa does not reduce the incidence of red-cell transfusion among critically ill patients, but it may reduce mortality in patients with trauma. Treatment with epoetin alfa is associated with an increase in the incidence of thrombotic events.
By applying the results of the adult trial to the PICU, and to treat 31% of the children with prophylactic erythropoietin and thereby expect a reduction of one red blood cell transfusion for every 17 treated patients.