Page 2588 - Hematology_ Basic Principles and Practice ( PDFDrive )

Chapter 159 Hematologic Problems in the Surgical Patient 2305

TABLE Risk for Bleeding With Surgical or Invasive of any bleeding episodes, including results of prior hemostatic testing,
159.1 Procedures as well as careful attention to the family history. The physical exami-
nation should focus on evidence of bleeding and on identifying
Risk Type of Procedure Examples systemic disorders such as hepatic or renal disease. If the history of
Low Nonvital organs involved, Lymph node biopsy, dental bleeding is negative or minimal, appropriate laboratory testing would
exposed surgical site, extraction, cataract include a PT/INR, aPTT, and a biochemical profile to evaluate
limited dissection, extraction, most cutaneous hepatic and renal function. A complete blood count and examination
percutaneous access surgery, laparoscopic of the peripheral blood smear are useful to identify myeloproliferative
procedures, coronary disorders, gray platelet syndrome, or thrombocytopenia. If the history
angiography is suggestive of a hemostatic abnormality, a full evaluation is indicated
and additional specific testing is usually required because von Will-
Moderate Vital organs involved, Laparotomy, thoracotomy, ebrand disease; mild deficiencies of factors VIII, IX, and XI; severe
deep or extensive mastectomy, major factor XIII deficiency; platelet function defects; and fibrinolytic
dissection orthopedic surgery, abnormalities may not be identified by global screening tests (see
pacemaker insertion
Table 159.2).
High Bleeding likely to Neurosurgery, ophthalmic
compromise surgical surgery, cardiopulmonary
result, bleeding bypass, prostatectomy or HEMOSTATIC AGENTS
complications bladder surgery, major
frequent vascular surgery, renal A variety of hemostatic agents are available and may be useful for the
biopsy, bowel polypectomy prevention or treatment of bleeding in the surgical patient. These
agents work through a variety of mechanisms to facilitate hemostasis,
including enhancement of primary hemostasis, enhancement of
thrombin generation and fibrin formation, and inhibition of fibrino-
TABLE Preoperative Hemostatic Evaluation lysis. However, it is important to note that there is a paucity of
33
159.2 safety data involving hemostatic agents because most trials have been
designed to assess therapeutic efficacy rather than potential complica-
Routine Screening 33,34
Surgical Risk Approach tions, including thrombosis. The use of desmopressin, topical
Low History only hemostatic agents, antifibrinolytic agents, and recombinant factor
VIIa (rFVIIa) will be discussed here. Blood products (platelets, fresh-
Moderate or high History, PT/INR, aPTT, platelet count frozen plasma, and cryoprecipitate) and factor VIII and IX concen-
Consultation History trates are discussed elsewhere (Chapters 112 and 115–117).
Negative or minimal for PT/INR, aPTT, platelet count, biochemical
bleeding profile, complete blood count with
differential, review of peripheral smear Desmopressin
Suggestive of bleeding Add to above as indicated: platelet function
disorder tests, von Willebrand antigen, ristocetin Desmopressin (1-deamino-8-D-arginine vasopressin, or DDAVP)
cofactor, factor VIII, factor IX, factor XI, is a synthetic analogue of the antidiuretic hormone arginine vaso-
factor XIII assays pressin. Intravenous, subcutaneous, or intranasal administration of
DDAVP results in transient increases in plasma concentrations of
aPTT, Activated partial thromboplastin time; INR, international normalized ratio; factor VIII and von Willebrand factor as a result of their release
PT, prothrombin time. 35
from vascular endothelium. Peak levels (typically two to four
times baseline) are achieved 30–60 min after intravenous and
36
60–90 min after subcutaneous or intranasal administration. Doses
is usually necessary to establish a specific diagnosis. 25-27 If clinical may be repeated at intervals of 12–24 hours, but tachyphylaxis may
37
suspicion is high, further testing is indicated even with normal occur after three or four doses, limiting further usefulness of
26
PFA-100 results. Thus the PFA-100 should not be used for general DDAVP. Expression of glycoprotein Ib (GPIb) and GPIIb/IIIa on the
38
unselected screening. 27 platelet membrane is also enhanced after DDAVP administration.
Although some studies have demonstrated the ability of the DDAVP is the treatment of choice for patients with mild hemophilia
PFA-100 to predict recurrent ischemic events following percutaneous A or type 1 von Willebrand disease who require low-risk surgi-
29
28
coronary interventions and coronary artery bypass graft surgery, cal procedures. Moderate- or high-risk procedures usually require
37
such testing does not predict bleeding in patients undergoing cardiac administration of clotting factor concentrates. DDAVP may also
or hip fracture surgery. 30-32 be useful for patients with congenital or acquired platelet function
Notwithstanding the controversy about the value of preoperative disorders. 36,38,39
laboratory screening, it is reasonable to personalize the approach to DDAVP does not reduce blood loss or transfusion requirement
preoperative evaluation depending on the hemostatic risk of the after cardiopulmonary bypass surgery. 40,41 Worrisome also is the fact
proposed surgery or invasive procedure (Tables 159.1 and 159.2). A that a metaanalysis shows a 2.4-fold increase in perioperative myo-
41
hemostatic history should always be obtained, and no laboratory cardial infarction in cardiac surgery patients treated with DDAVP.
testing is required in patients undergoing procedures at low risk for Thus the routine use of DDAVP in cardiac, orthopedic, or other
bleeding. For procedures associated with a high risk of bleeding, elective surgical procedures is not recommended. 34,42 A more recent
screening could include a PT/INR, aPTT, and determination of the metaanalysis of 38 randomized placebo-controlled trials that included
platelet count. nearly 2500 surgical patients found that DDAVP slightly reduced
In practice, hematologists are rarely consulted for routine screen- blood loss (by approximately 80 mL) and transfusion requirements
ing because surgeons have adopted approaches based on their own (by approximately 0.3 units) but did not reduce the proportion of
43
training and local practice patterns. Instead, consultation is sought patients receiving transfusions. Although the authors acknowledged
because of a history suggestive of a bleeding disorder or because an that the clinical impact of the reduced transfusion requirement is
abnormal test result is found on screening. If a referral is requested questionable, they felt this could not be ignored because of the low
because of an abnormal screening test, the abnormality needs to be cost of DDAVP. The incidence of thromboembolic events in the
identified. However, regardless of the reason for the referral, the DDAVP and placebo groups was similar (5.4% and 4.6%, respec-
history is of central importance and must include a thorough review tively), but they pointed out that identification of harm from DDAVP