Blood Transfusion in Acute Trauma Prof. W. O. Mwanda

Background Use of blood and blood components/products- save life -reduce risks of transfusion transmissible diseases, most particularly the transmission of HIV and other infectious agents. Red cells ,and plasma a number of clinical circumstances.

Decision for red cell transfusion should not be based on haemoglobin levels alone, consider the clinical circumstances of the patient. No precise formula to be used in the decision to transfuse particularly red cells.

There is no uniform formula to be used in the decision to transfuse red cells. some clinical and laboratory parameters that assist the doctor in the decision to transfuse. There are surgical situations, which require transfusion. Rule1, the maintenance of adequate oxygen delivery is the goal of red cell transfusions.

Alveolar-capillary diffusion Haemoglobin O2 binding Haemoglobin level Functions associated with oxygen delivery Ventilation Alveolar-capillary diffusion Haemoglobin O2 binding Haemoglobin level Blood flow Cardiac output Stroke volume Heart rate Peripheral resistance Oxygen extraction Haemoglobin O2 affinity Cellular respiration

During stress and disease states, the ability for considerable compensation by one function of the oxygen delivery chain to overcome deficiencies of another. Increased oxygen extraction Decreased haemoglobin oxygen affinity.

These compensatory mechanisms take time to develop to their full efficiency. The patient may not recognize a developing anaemia until it becomes severe.

ACUTE FALL IN HAEMOGLOBIN Does not allow time for compensatory mechanisms to become fully effective. oxygen delivery is less and tissue anoxia may occur at higher haemoglobin levels

Massive Transfusion Transfusion equal to or exceeding the patient’s blood volume within a 24-hour period. In the adult male who weighs 70 kg, this translates to an estimated replacement of 4-5 litres of blood, or transfusion of 16-20 units of packed red blood cells (RBCs). Consequently, massive blood loss is the loss of between 30 and 50% of total blood volume.

This definition is more useful in the clinical setting because amounts of blood loss can be tied to clinical signs and symptoms and the development of shock. severe haemorrhage as a rate of blood loss >150ml/min, which could lead to the loss of one half of the victim’s blood volume within 20 minutes. These patients are relatively easy to recognize from their obvious signs of shock, patients with less severe haemorrhage are more difficult to define on clinical grounds.

Blood loss and haemorrhagic shock should be classified for the purposes of treatment as follows:

Class 1 Haemorrhage Blood loss is <15% of total blood volume. The common clinical manifestations include normal or slightly increased pulse rate, normal blood pressure and pulse pressure, and no changes in signs of tissues perfusion. Volume losses are typically restored from extracellular fluid resources.

Class II Haemorrhage Blood loss 15-30% of total blood volume. In this situation, the heart rate is increased and systolic blood pressure is typically normal, but pulse pressure decreases in response to vasoconstriction and tachycardia. A drop in blood pressure can be seen with change in posture from supine to seated (positive tilt test). Capillary refill may be delayed, respiratory rate may be increased, and patients may demonstrate some signs of anxiety as a result of decreased cerebral perfusion.

Class III Haemorrhage Blood loss of 30-40% of total blood volume. Symptoms include tachycardia, decreased systolic blood pressure and pulse pressure, delayed capillary refill, and a progressively increasing respiratory rate. Urine output may become decreased and the patient may become confused at this level.

Class IV haemorrhage: Blood loss >40% of total blood volume. Clinical signs are those of shock: tachycardia, hypotension, oliguria, and lethargy or coma. Patients with Class IV haemorrhage are those who fall into the massive transfusion category. Massive transfusion volume guideline for those aged less than 20 years Patient’s Age in years Units transfused Less 2 2.0 2 – 4 3.0 4 – 6 4.0 6 – 8 5.5 8 – 10 5.5 10 – 12 6.5 12 – 14 8.0 14 – 16 9.0 16 – 18 10.5 18 12.0

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