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April 2003
Richard A. Savage, MD
Q. Our anesthesiology department has requested a thromboelastograph, or
TEG, to assess coagulation in the operating room. How useful is
the TEG and when should it be used? Should medical technologists
or perfusionists operate it? Who should interpret the results? Is
the TEG useful for ob-gyn and emergency room patients?
A.
We use the thromboelastograph primarily to assess hemostasis during
liver transplantation and cardiopulmonary bypass. We run the TEG
in an operating room satellite lab and transmit the resulting TEG
curve to the operating room using closed-circuit television. This
setup allows everyone in the operating room to see the TEG output.
We’ve been doing this for more than 10 years. Our model of
TEG prints a paper report that is easy to transmit via a black-and-white
television camera. I have found that the modern TEG manufactured
by Haemoscope produces an output on a computer screen that is more
difficult to transmit.
We decided to operate the TEG in the laboratory to provide results
to as many users as possible with the fewest instruments; to allow
the lab to remove heparin when needed (intraoperative TEGs during
cardiopulmonary bypass); and to consolidate all stat coagulation
testing for the operating rooms, including the frequently ordered
prothrombin times, fibrinogens, and platelet counts.
The output from the TEG is a complex mix of coagulation factor levels,
platelet counts, and fibrinolysis. The maximum amplitude on the
TEG is directly related to platelet count and fibrinogen concentration.
A decline in amplitude after reaching the maximum is related to
excess fibrinolytic activity. The “r” and “k”
clotting times are related to coagulation factor levels but are
also dependent on platelet phospholipid. Adding contact activators
such as kaolin makes the “r” value similar to an activated
clotting time, while adding thromboplastin makes it similar to a
prothrombin time. The TEG angle is the most complex variable because
it relates to, and is affected by, nearly everything.
A normal TEG suggests that bleeding is not caused by a coagulation
factor deficiency, platelet count or function, or excess fibrinolysis.
This finding can be useful in patients who are bleeding after cardiopulmonary
bypass. Decreased amplitude suggests reduced platelet count or fibrinogen.
The TEG’s most useful indication is for excessive fibrinolysis,
which occurs in liver transplant patients due to lack of tissue
plasminogen activator clearance during the anhepatic phase and during
cardiopulmonary bypass due to an excess release of t-PA from endothelium.
Excess fibrinolysis is usually not reported on any other test. D-dimer
is not a good surrogate for measuring excess fibrinolysis because
it is more a measure of intravascular fibrin than lysis.
If you have stat PT, fibrinogen, and platelet count available, the
main result from the TEG would be an indication of fibrinolysis.
We do TEG and standard coagulation testing for the operating rooms.
Bibliography
Chandler WL. The thromboelastography
and the thromboelastograph technique. Semin Thromb Haemost.
1995;21(suppl.4): 1–6.
Chandler WL, Patel MA, Gravelle L, et al. Factor XIIIA and clot
strength after cardiopulmonary bypass. Blood Coagul Fibrinolysis.
2001;12:101–108.
Spiess BD, Gillies BS, Chandler W, et al. Changes in transfusion
therapy and reexploration rate after institution of a blood management
program in cardiac surgical patients. J Cardiothorac Vasc Anesth.
1995; 9: 168–173.
Wayne L. Chandler, MD
Department of Laboratory Medicine
University of Washington
Seattle
Member, CAP Coagulation
Resource Committee
Q. We
recently encountered a situation in which a dermatologist who interprets
his own slides refused to send a patient’s previous slides
to our institution, where the patient was now being treated. The
slide review was requested to help direct patient care and was not
expected to have medicolegal implications. The patient had executed
a proper release form, but the dermatologist refused to comply.
(The laboratory that cuts his blocks did send a recut, but it was
nonrepresentative.) It would not be practical for us to review the
slides in the dermatologist’s office because he is located
several states away. Do the laws and code of ethics that apply to
pathologists in situations of this type apply also to dermatologists?
What can the patient do to get the dermatologist to comply with
her request, short of initiating legal action, which would probably
be protracted and expensive?
A. I
would restate the first question—do the laws and code of ethics
that apply to pathologists in situations of this type also apply
to dermatologists?—as follows: Do the same legal and ethical
obligations applicable to pathologists in this sort of situation
apply also to dermatologists, and, if so, do these obligations require
the dermatologist to transfer the slides?
The same legal requirements that govern pathologists apply equally
to dermatologists practicing in the same state. However, the letter
does not identify the jurisdiction in which the dermatologist practices
or the source of insurance coverage for the patient. Thus, I cannot
determine which state law controls this incident or whether Medicare
or Medicaid regulations apply.
In any event, the Principles of Medical Ethics of the American Medical
Association apply equally to pathologists and dermatologists. Those
principles govern directly if the physicians are members of the
AMA or of a medical society, such as the College of American Pathologists,
that has adopted the principles. Even for physicians who are not
members, the principles provide important guidance on ethical issues.
In my opinion, the dermatologist’s refusal to provide the
slides appears to violate Principle IV of the Principles of Medical
Ethics as construed by the Council on Ethical and Judicial Affairs
(CEJA) in Opinion 7.01. (See AMA Code of Medical Ethics, 1998–1999
edition). Principle IV provides as follows: “A physician shall
respect the rights of patients, of colleagues, and of other health
professionals . . . .” That principle was interpreted in a
manner bearing on the question at issue here in Opinion 7.01, titled
“Records of Physicians: Availability of Information to Other
Physicians.” Opinion 7.01 of CEJA reads as follows:
“The interest of the patient is paramount in the practice
of medicine, and everything that can reasonably and lawfully be
done to serve that interest must be done by all physicians who have
served or are serving the patient. A physician who formerly treated
a patient should not refuse for any reason to make records of that
patient promptly available on request to another physician presently
treating the patient. Proper authorization for the use of records
must be granted by the patient. Medical reports should not be withheld
because of an unpaid bill for medical services.” (Emphasis
supplied.)
Opinion 7.01 strongly suggests that the refusal of the dermatologist
to provide the slides at the request of the patient is unethical.
The dermatologist appears to be a “physician who formerly
treated [the] patient.” The dermatologist is being requested
to make the slides available to the institution at which the patient
is currently being treated. Moreover, the patient presumably has
given the proper authorization. Accordingly, Opinion 7.01 seems
applicable.
Of course, slides are not paper or electronic “medical records.”
But the same governing principle that requires transmission of medical
records—that is, that “everything that can reasonably
and lawfully be done” to serve the interest of the patient—would
appear to require that the slides be sent. To be sure, the dermatologist
may have concerns about potential liability issues if the patient
subsequently sues for malpractice and the dermatologist is unable
to produce the relevant slides. However, that concern is addressed
by having (1) a signed statement from the patient directing a transfer
of the slides and (2) a signed statement from the receiving institution
acknowledging receipt of the slides and promising to provide them
if needed for medicolegal reasons.
The second question is: Short of initiating legal action, what can
the patient do to get the dermatologist to transfer the slides?
At the outset, I would recommend that the institution that is supposed
to receive the slides (or the pathologist at that institution) contact
the dermatologist to discuss the refusal to provide the slides.
If the dermatologist’s refusal is based on potential medicolegal
concerns, it might be possible to allay those concerns through the
sort of documentation discussed in the preceding paragraph. Alternatively,
if there is some other basis for the refusal, reasonable efforts
could be made to work out a solution. Further, the dermatologist
can gently be reminded of his or her potential legal liability if
the patient’s condition worsens by virtue of the refusal to
provide the slides.
If the dermatologist is intransigent, several steps can be taken
short of initiating litigation:
- If the dermatologist is a member of a hospital medical staff,
that medical staff can be contacted and asked to intervene.
- If the patient is covered by a managed care organization and
the dermatologist is on the panel of providers for that MCO, the
MCO can be asked to put pressure on the dermatologist.
- A complaint can be filed with the board of medical examiners
in the state in which the dermatologist is licensed asking the
state board to take action.
None of these steps should involve significant costs or risk of
liability.
Jack
R. Bierig
CAP General Counsel
Sidley Austin Brown & Wood
Chicago
Q. Should positive urines for proteins be confirmed by the
sulfosalicylic acid method when using the standard protein dipstick
test since the standard test is less sensitive than the microalbumin
dipstick test?
A.
This question suggests that the microalbumin test could be used
to confirm a positive result for protein using urine dipstick methodology.
It also raises the issue of confirming a positive dipstick result
with an alternative procedure, such as sulfosalicylic acid.
The microalbumin test is designed specifically to monitor patients
with established diabetes mellitus for excretion of small amounts
of albumin below what can be detected by urine dipstick testing.
A positive result for microalbumin allows early therapeutic intervention
to forestall the onset of diabetic nephropathy. Indications for
this test, therefore, are unrelated to those for regular urine dipstick
screening, and neither test should be used to corroborate the results
of the other.
Both the dipstick test and the SSA procedure, however, are acceptable
methods to detect proteinuria in the general population and are
of comparable sensitivity. The dipstick is selective for albumin,
while SSA will precipitate a broad range of proteins, including
albumin. Because the dipstick test is generally considered to be
a screening test, as opposed to a diagnostic test, there is no regulatory
requirement for reflex testing to confirm results, and the CAP checklists
do not specifically address this issue.
If the dipstick result is read manually, instead of by an instrument,
the color change between “negative” and “Tr/1+”
is very subtle and may be difficult to interpret. Furthermore, the
color change may be difficult to detect in urines that are intensely
colored by a variety of agents, such as bilirubin or hemoglobin.
In conclusion, whether you wish to go through the extra effort and
expense to establish a confirmatory test for urine specimens that
are positive for protein will depend on such factors as the reason
for testing, the population being tested, the methodology you employ
for reading the strips, and the desire to correlate results between
various testing sites.
David J. Blomberg, MD
Department of Pathology
Miller-Dwan Medical Center
Duluth, Minn.
Member, CAP Hematology/Clinical Microscopy
Resource Committee
Q. For
how long following stroke, disseminated intravascular coagulation,
or trauma surgery, and postpartum is a decrease in protein C or
S acceptable?
A.
Protein C, protein S, and antithrombin become temporarily decreased
by thrombosis, disseminated intravascular coagulation, and surgery.
Protein S, and occasionally antithrombin, become decreased during
pregnancy or estrogen use.
The amount of time needed to return to the normal range following
a thrombotic event, surgery, or recovery from DIC has not been well
documented. It probably varies, depending on the severity and duration
of the illness and the type of surgery. Studies involving cardiopulmonary
bypass have shown that protein C,1,2 protein S,2 and antithrombin1,2
on average remain lower than their preoperative baseline on the
first post-bypass day but are already back in the normal range (or
for antithrombin, near-normal).
It does not appear to be necessary to defer testing of protein C,
protein S, or antithrombin following most thrombotic events, DIC,
or surgeries, except for cardiopulmonary bypass procedures or severe
events. However, if a low value is obtained in one of these conditions,
the assay should be repeated once the patient has fully recovered.
How long one should wait has not been defined, but anecdotal experience
indicates that a few days to one week is probably adequate for most
patients. If the value remains low, retesting can be performed after
another two to three months of clinical stability.
In studies of protein S levels following pregnancy, protein S remains
low at one to two weeks postpartum and returns to normal when measured
again at six to eight weeks postpartum.3,4 In at least one postpartum
case, however, it took 12 weeks for protein S to return to normal.5
It is therefore reasonable to wait at least two to three months
after pregnancy or discontinuing estrogen to measure protein S.
It probably is not necessary to defer testing of antithrombin during
pregnancy or estrogen use, but if a low value is obtained, repeat
testing should be performed no sooner than two months after delivery
or discontinuing estrogen.
References
- Feindt R, Volkmer I, Seyfert UT, et al. The
role of protein C as an inhibitor of blood clotting during extracorporeal
circulation. Thorac Cardiovasc Surg. 1991; 39: 338–343.
- Boldt J, Schindler E, Welters I, et al. The
effect of the anticoagulation regimen on endothelial-related coagulation
in cardiac surgery patients. Anaesthesia. 1995; 50: 954–960.
- Kjellberg U, Andersson NE, Rosen S, et al. APC
resistance and other haemostatic variables during pregnancy and
puerperium. Thromb Haemost. 1999; 81: 527–531.
- Fernandez JA, Estelles A, Gilabert J, et al.
Functional and immunological protein S in normal pregnant women
and in full-term newborns. Thromb Haemost. 1989; 61:
474–478.
- Comp PC, Thurnau GR, Welsh J, et al. Functional
and immunologic protein S levels are decreased during pregnancy.
Blood. 1986; 68: 881–885.
Elizabeth
M. Van Cott, MD
Director, Coagulation Laboratory
Department of Pathology
Massachusetts General Hospital
Boston Member, CAPCoagulation
Resource Committee
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