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Preoperative assessment including screening for hematological problems, identifying potential "bleeders" (patients who may bleed) and hematological tests are found at Hematological complications.

Massive hemorrhage and bleeding and cardiac tamponade are dealt with in the relevant links.

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 [1],18,19,20.

ReferencesEdit

1.Davie EW,Ratnoff OD.Waterfall sequence for intrinsic blood clotting. Science 145:1310–2, 1964

2.Hoffman M, Monroe DM, Roberts HR. Cellular interactions in hemostasis. Haemostasis 1996; 1: 12–16

3.Dahlback B. Blood coagulation. Lancet;355(9215):1627–32, 2000.

4.Smetana GW, Macpherson DS. The case against routine preoperative laboratory testing. Med Clin North Am;87:7–40, 2003

5.Suchman AL,Mushlin AI. How well does the activated partial thromboplastin time predict postoperative hemorrhage?JAMA;256:750–3, 1986

6.Eckman MH et al Screening for the risk for bleeding or thrombosis Ann Inten Med 138(3) : 15, 2003

7.EisenbergJM,GoldfarbS.Clinica lusefulnes of measuring prothrombin time as a routine admission test.ClinChem;22:1644–7, 1976

8.Ramsey G,Arvan DA,Stewart S,etal.Do preoperative laboratory tests predict blood transfusion needs incardiac operations? J Thorac Cardiovasc Surg 85:564–9, 1983

9.Sady S,Sweitzer B. Hematologic issues.In:Swetizer B,editor.Handbook of pre-Operative assessment and management Philadelphia:LippincottWilliams&Wilkins p.159–95, 2000

10.Cobas M.Preoperative assessment of coagulation disorders. Int Anesthesiol Clin ;39:1–15. 2001

11.McKenna R.Abnormal coagulation in the postoperative period contributing to excessive bleeding Med Clin North Am ;85:1277–310, 2001

12.Luddington RJ Thromboelastography/thromboelastometry Clin Lab Haem 27:61-90,2005

13.RohrerM, Mechelotti M, Nahrwold D. A prospective evaluation of the efficacy of preoperative coagulation testing. Ann Surg;208:554–7, 1988

14.Cammerer U.,Dietrich W.,Rampf T.,Braun S.& Richter J.The predictive value of modified computerized thromboelastography and platelet function analysis for postoperative blood loss in routine cardiac surgery. Anesthesia and Analgesia 96, 51–57, 2003

15.Rodgers RP ,Levin J. A critical reappraisal of the bleeding time. Semin Thromb Hemost ;16:1–16,1990

16.Harrison P.The role of PFA-100 testing in the investigation and management of hemostatic defects in children and adults. Br J Haematol;130:3–10, 2005

17.Jilma B. Platelet function analyzer (PFA-100) :a tool to quantify congenital or acquired platelet dysfunction.J Lab Clin Med 138:152–63, 2001

18.Litaker D.Preoperative screening. Med Clin North Am;83:1565–81, 1999.

19.Dagi TF The management of post operative bleeding Surg Clin N Am 85,1191–1213, 2005 20 Soliman DE Broadman LM Coagulation defects Anesthesiology 24:549-578, 2006

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