Preoperative assessment including screening for hematological problems, identifying potential "bleeders" (patients who may bleed) and hematological tests are found at Hematological complications.
Management of post operative bleeding Edit
The first step to diagnose the aetiology of bleeding is to recognize the the patient is bleeding. This might be not that easy.Points that help in deciding the significance of bleeding are:
- A rising lactate
- the presence of acidosis in the blood gas analysis (can be the first sign of blood loss and hypoperfusion). This is especially true if this persists despite correction with sodium bicarbonate/THAM.
- Unexplained Tachycardia.
- Diminished cardiac output and filling pressures.
- Repeated episodes of transient hypotension that are corrected by fluid administration.
- Blood pressure alone is not a good indicator, since suppression of neurovascular reflexes and increased vagal tone might cause hypotension, as well as the anaesthetic substances.
- Vital signs might remain stable, especially in the young, until shock ensues. Normal blood pressure may be preserved until 1.5 to 2 L of blood is lost, nearly 40-50% of total circulating effective volume.
- Because of aggresive fluid administration and fluid shifts, hematocrit and hemoglobin may be low, and can be dismissed as artifacts of hemodilution.
- Drains might become obstructed, kinked, blocked or malpositioned, thereby providing false sense of security.
- Last but not least, bleeding might be remote from the site of surgery or it may accumulate in an undrained compartment.
The surgeon must, therefore, be constantly in search of bleeding sources; thorough, constant evaluation is still the best approach to identify occult bleeding sources, and observation of capillary perfusion pressure, urinary output, colour , oedema and discoloration of extremities, low central venous pressures, and other signs must be always searched actively, and imaging such as CT, angiography, ultrasound and other techniques might aid and indicate endovascular repair of an unsuspected bleeding vessel.
The coexistence of technical and coagulopathic causes of bleeding is not uncommon, and it may be difficult to address the technical causes before stabilizing the coagulopathy. The use of a massive transfusion guideline is very useful, since excessive transfusion of blood products might induce or worsen the hemostasis disturbance. Both the surgical technical intervention and the control of the coagulopathic cause of bleeding have to be pursued simultaneously, and in this regard, thromboelastography is a very useful tool.
First steps towards improving hemostasisEdit
- Correction of acidosis
- Avoidance of cyclic hyperresuscitation
- Avoiding unnecessary hemodilution,
- Diagnosis and control of hypothermia ,
- Avoidance of fluids that can further impair coagulation such as hetastarch
In order to reduce unnecessary transfusions in the case of massive bleeding, an appropriate guideline for massive transfusion should be followed. The most recently published is available at the british journal of hematology website. If one decides to use factor concentrates or recombinant activated factor VII, better do it before the patient is hypothermic and acidotic, when such measures have reduced efficacy in reverting the coagulopathic state. TEG/ ROTEM guided algorhythms seem to be very useful in this setting, reducing transfusional needs ,18,19,20.
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