[HSF] My! Oh, My!
Tea Acuff
tacuff at swbell.net
Thu Nov 8 16:49:02 EST 2007
Ben,
Not quite what I had in mind. Of course I am not able to store much in mind. One thing I was thinking with this posting was a couple of paradoxes perhaps you can help me since it is right up your expertise.
Our understanding and our interactions with patients (eg therapies) are both temporal and directional processes not static or timeless. The tools, math and logic, we use use to describe our observations are timeless and symmetrical both the worlds of absolutes. How do these tools change how we feel about what we observe?
We often forget in our science that experiments never prove the logic of the processes we see, they only make the (contra)logic (the null hypothesis) unlikely if the experiment is positive.
Unfortunately when we see a study that shows a difference we immediately move this analysis of the temporal and chaotic to the world of the absolute and timeless, where any valve, blockage, symptom, or measurement becomes EVERY valve, etc., and is translated to the world of guidelines and supreme authority (or its secular counter part). I suppose most can see how this effect may occur.
However, I was wondering about the twisted corollaries of this and perhaps you can help. Since math is symmetrical, in making a study larger and larger to show more and more "powered" connections, does not these very large, expensive, and highly regarded sources of enlightenment as they get larger and larger or more universal, does this actually mean that they have less and less to do with the single patient that is sitting before us in the limited and temporal world? ( Note. As in the theory of relativity, assume there is a constant, but here the constant is not the speed of light but a "p of .001".)
Tea (sorry, tea)
----- Original Message ----
From: Ben Bidstrup <benjamin.bidstrup at bigpond.com>
To: OpenHeart-L at lists.hsforum.com
Sent: Thursday, November 8, 2007 1:24:14 PM
Subject: Re: [HSF] My! Oh, My!
Very simple and based on FDA etc. The trials were done with full dose
and half dose. No dose ranging etc was done in the early stages.
Why you ask.
Because several clever biochemists calculated a dose that would
maintain a level in the circulation that would inhibit kallikrein
(4KIU/ml). A hard job given the vagaries of CPB and the addition of
fluid etc.
An early study measured the levels (as have several others) and the
dose was altered to maintain that level.
FDA asked for studies to be done they were done with high dose. The
sde effect profile was determined with this dose regime. Hence they
were only permitted to market it this way.
Do you use a half or a quarter dose of penicillin or a 5th generation
quinolone?
Not likely.
The lower doses were generated partly based on cost to the end user
and on several small studies that had some theoretical advantages - a
first pass phenomenon.
Studies into the half dose were done as part of the FDA submission. A
subsequent analysis showed the half dose not as safe as the high dose
regime David Royston and I described in the Lancet article in 1987
and my paper in the JTCVS in 1989.
22 years of use of the drug has not shown up the mortality impact nor
the impact on the kidney Hal speaks about so knowledgeably with his
accurate data.
The BART study has shown a trend to increased mortality in a high
risk group. No-one not even me or Bayer knows more that that. We
have to await the analysis which will be done by the BART people -
not FDA not Medicine Canada not Bayer. In this day and age, the
overabundance of lawyers in the US has its downside.
I have had many colleagues tell me they have not seen any issues they
can relate directly to this drug.
For those of you who do not understand the issues of large trials,
there are rules that apply to interim analyses and to stopping. Again
caution is usually the watchword here.
And to reiterate I have been associated with aprotinin (Trasylol)
since 1985. Many of the studies have been sponsored by Bayer around
the world. (After all what NIH, MRC or NHMRC would give money to
sponsor a large expensive study in cardiac surgery). I have worked
closely with them as have many others all of whom are highly
respected in their fields.
I stand by my findings and views. Most are based on science not a
maybe this happened.
Cardiac surgery is a contact sport a bit like rugby. The rules keep
changing in an attempt to make it safer, but injuries still occur.
The heart lung machine still has inherent morbidity. Mind you OPCAB
has not necessarily reduced that.
What drugs are given by your anaesthetist and what are their effects?
I reviewed all anaphylactic reactions over a 7 year period in one
hospital in cardiac surgery. There were 7 if I recall. None was
associated with aprotinin use. Latex, muscle relaxants were the
causes identified.
>Ani, part of the problem is caused by Bayer themselfs. Bayer did
>very agressive marketing. They wanted me to use aprotinin on
>everyone with full dose. Even my friends in shanghai was using it on
>everyone, because they were told it is miracle drug.
>
>Z Zhou
>
>
>Sent via BlackBerry by AT&T
>
>-----Original Message-----
>From: Ani Anyanwu <anianyanwu at hotmail.com>
>
>Date: Thu, 8 Nov 2007 10:01:18
>To:<openheart-l at lists.hsforum.com>
>Subject: RE: [HSF] My! Oh, My!
>
>
>Tea
>
>'Convenience drug' is a term I have used in the past specifically
>for the use of Factor VII but can apply to other drugs too - maybe
>trasylol.
>
>Some drugs are essential such as antibiotics in septicemia. Some
>drugs are of debatable essence such as digitalis in heart disease.
>Some drugs are non-essential and of questionable efficacy and use
>such as antibiotics in pharyngitis. Some drugs are to treat the
>physician's own anxiety or to fulfil his/her particular nuances or
>beliefs such as antibiotics in patients with chest tubes. Then there
>are those drugs are used for convenience such as hormonal therapy to
>suppress mensturation. An extension of the last concept is the
>doctors convenience.
>
>Convenience therapies are not essential for the patient but make
>life more convenient for the physician or sometimes the patient. For
>example, I open majority of my redos on cardiopulmonary bypass -
>many could argue I do so for my convenience and that is it not
>necessary if I learnt to open a redo properly and safely like they
>do that I would not need to do so. Doctors who give every patient
>dobutamine or epinephrine is also an example of convenience therapy.
>You sleep better at night and less likely to be paged for a low
>output if you treat pre-emptively. Protamine given routinely when a
>patient returns to ICU is also an example of convenience therapy.
>Blood product transfusions is also a commonly used convenience
>therapy for surgeons who give products routinely for any operation.
>There is rarely an operation where use of blood products is
>essential in all cases as we rapidly learn when the Jehovah's
>witness walks in through the door. Even liver transplantation has
>been undertaken in these patients.
>
>Factor VII unlike what others suggest is actually a prime example of
>a convenience drug and has been used as such several times in my
>institution. A surgeon does a complex arch reconstruction and has
>two options - pack and pack for 3 hours then go home or give Factor
>VII and maybe go home in 5 minutes. The drug *does* work. Many
>patients receive this drug in the initial operative setting and not
>after re-exploration for bleed and demonstration of coagulopathy.
>Mind you there are valid arguments for use of Factor VII as a
>convenience therapy which could benefit the patient.
>
>1) Transfusions are associated with higher morbidity and mortality.
>Preventing or halting blood loss may be preferable to hours of
>transfusion and packing in the OR
>2) Longer OR times may be associated with higher complications due
>to hypothermia and infection rates
>3) A surgeon who is tired or who would rather not be there may be
>harmful to the patient
>4) Re-explorations may be harmful to the patient
>5) If used as an *alternative* to plasma transfusions then we have
>potentially less side effects to deal with
>6) In patients with tenuous right heart function - notably heart
>transplantation and LVADs - the conventional treatment (blood
>product transfusion) or effect of coagulopathy (blood loss) can lead
>to catastrophic hemodynamic collapse. A pure pharmacological agent
>could treat the coagulopathy without such side effects.
>
>While aprotinin is beneficial in some cases, in most cases it is a
>convenience drug. There is little evidence that any antifibrinolytic
>leads to better clinical outcomes in the majority of settings it is
>used. However if you want to operate on a patient on Plavix and
>finish the surgery in reasonable time and not be paged all night for
>bleeding, an antifibrinolytic might help. Alternatively if you don't
>have one you can take extra care with hemostasis such as Ed outlined
>in his strategy for Jehovah's witnesses and probably have the same
>effect. As I said I did a sixth time sternotomy two days ago without
>aprotinin and patient bled 700mls the first night.
>
>Problem is that Factor VII has also side effects which to my mind
>are far more frequent and, if they occur, severe than those of
>aprotinin. It is for this reason it should not be a convenience
>drug. If the risk profile of the drug was low (as say aspirin), it
>would be a very useful convenience drug to give all our patients and
>while not an essential drug it would reduce the morbidity and also
>reduce the complications and complexity of heart surgery. The latter
>has been my basis for very liberal use of aprotinin till last week.
>I will not give up on my use of convenience therapy as I will now
>switch to other antifibrinolytics till they too are taken off the
>shelf whenever a researcher with a gripe chooses to pursue some
>vendetta with the manufacturing company (after all who has come up
>with a biologically plausible reason why aprotinin causes renal
>failure or death but tranexamic acid or EACA does not?).
>
>I do not know though about "american medical evidence" though I
>think I could write some on that too - was that term from me also?
>Regardless of the fact that FDA has ruled, we still have to think
>about these issues: now Vioxx and Trasylol are gone, the FDA, the
>Manganos, the Lawyers etc will look for new targets...I have seen
>some nasty things recently on patients getting methylene blue
>lately, also a lot of the patients I see on Nitric Oxide seem to
>have renal failure and many die too...
>
>Ani
>
>
>
>
>> Date: Wed, 7 Nov 2007 19:59:31 -0800> From: tacuff at swbell.net> To:
>>OpenHeart-L at lists.hsforum.com> CC: > Subject: [HSF] My! Oh, My!> >
>>Listening to these threads on aprotonin, Factor VII, and hybrid ORs
>>begs the question: why so much diversity of opinion if we are
>>looking at that same "flat" world out there with the same universal
>>standards of evidence that are even classified for us (eg IA, IIc ,
>>etc)? The world is flat now is it not? We all have access to the
>>same clear and standardized evidence, right? We all look at the
>>same problems, right?> > I have read a few novel twists in these
>>discussions: "american medical evidence" and "convenience" drugs.
>>As is my wont, I usually twist the question and reexamine it. What
>>is then "unamerican evidence"? What drug exactly is an inconvenient
>>drug, or what would be the purpose of using such a drug?> > But as
>>to my original question, we could answer every medical and
>>especially every American medical question with a (Chomsky type)
>>economic answer. Does not anyone believe that there is somewhere in
>>our medical practice some answers that do not depend on economics
>>and fundamentally are biologic or medical in their answers, if you
>>will, in their nature? What then would be that nature, and why
>>might the evidence not be clear using our usual methods of asking
>>the question? Not surprisingly I have at least a couple of ways of
>>thinking about this that seem to me useful. What about you?> > On
>>the other hand the FDA has decided so why bother to think about it
>>at all?> > tea>_______________________________________________>
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--
Ben Bidstrup FRACS FRCSEd FEBCTS
Consultant Cardiothoracic Surgeon
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