[HSF] CPB - what the surgeon needs to know.

Sun Aug 12 08:27:59 EDT 2007

Following this conversation about what does a surgeon need to know has the sense of our favorite discussion, the comedic opera. 

It is as if one dropped in on NASCAR and observes the hundreds of thousands watching what at first glance appears to be noisy objects frantically chasing each other. We can describe, but not infer usefully without some understanding beyond the descriptive details. 

It is an epistemological problem. What do we know and how do we know it? 

At the heart of this discussion, which is what do we teach and what is learned, the ambiguous truth of Gregory Bateson is noted: "Those that lack all idea that they can be wrong can learn nothing except know-how." Certainly know-how is a good thing for a surgeon, a very good thing, but many of us feel it is not the mark of a master. I think his provocation is teaching us about presuppositions in our thinking. 

Let me try a different tact to perhaps interest you in thinking about thinking more clearly about what we do rather than how we do. As in my Nicaragua question comparing two different scenarios with different details may give us some insights as to the essence of the game that we play. 
CPB is a versatile tool that has taken painful decades to "know" it's most famous father. Dr. Gibbon completely gave up on knowing his child. Knowing is a very personal thing despite the assumption that it is the purview of public knowledge. Part of the problem is that we are now bound up in the details of our personal knowledge of a particular perspective (and presupposition). 

Instead of CPB lets call the "tool" a more generic cardiopulmonary support or CPS. As a comparison lets look at a different form of CPS, which we can call (Lilliheigh's) cross circulation (CC). What do we "need to know" about CC? I am not near the expert of the audience of HSF, but I do have the ability to ask a few fundamental questions (called stupid questions from a particular perspective). The answers raise some interesting thoughts. 

Let’s assume that Lilliheigh's successful CC program is defined as a system of knowledge as is Prassanna's CPB system. What does a surgeon need to know in these different systems? It appears that "knowing" means completely different things in these two systems. In CC the systems "knows" much more than the surgeons could ever hope to comprehend. It is my contention that this remains true even today despite Prasanna's CPB system's surgeon's great passion and encyclopedic wisdom. It may be that CPB over the decades has become a much more extreme and potentially useful (and dangerous?) than CC, but that is unclear. 

What this points out is that in CC what is needed is an understanding of what is required on the patient and surgeons side to accomplish the proposed surgical procedure. "Knowing" in CC is really a relational problem. How do we "connect to" the patient in the CC system safely? I would submit that this is the same problem in CPB. The surgeon must be able to connect, and not just attach tubes, to the CPB. In CPB the surgeon must "connect" to the perfusionist (whatever training), and to do that he must "know" the perfusionist. This requires a "understanding" including language and presuppositions for translation of information from the CPS system to the patient system, which is the surgeon's original but no longer only concern. 

All of you may now ask much more personal (and better) questions concerning the "need to know" for surgeons in your systems. I will briefly point out two different structures (perhaps of many) that allow this to happen. One I will call the "German structure", in which everyone plays off the same card set by the "chief", who ironically if it is an evolving structure, is working on different systems than the present "right" one. The other I will also somewhat arbitrarily call the (beautiful) American structure in which one knows intimately the individuals in the structure. In the German structure the parts are "interchangeable" because everyone is using the same "right" knowledge". In the American structure more diversity thought is allowed but knowledge of the players is more important. 
Obviously both structures have components of each other, and there is not a "right" knowledge anywhere to be found outside a personal epistemology. 

I would suggest, however, that the Roman legion was the dominate fighting force for centuries because the individual soldier "knew" with high probability what the man on each side of him and to his back was going to do no matter what was thrown at them. 

tea

----- Original Message ----
From: Ani Anyanwu <anianyanwu at hotmail.com>
To: openheart-l at lists.hsforum.com
Sent: Saturday, August 11, 2007 6:51:03 AM
Subject: RE: [HSF] CPB - what the surgeon needs to know.

Prasanna

You misinterpret what I say as usual! If you read again my original text you will find I am not in as much disagreement with you as you think. I clearly made an exception for the circumstances in which you practice - In India it certainly is necessary for the surgeon to know more than one does in the United States. 

However, perfusion in 2007 is different in the United States and in many other countries. Indeed, in New Jersey state next to me, by legislation two perfusionists must be in the room on every case - and this applies both to academic and non-academic centres. Of course perfusion catastrophies do occur. Indeed 3 weeks ago I had a tubing rupture in the roller head and my patient was without circulation at 34.5 degrees for eight minutes. I know you will suggest we could have made the time shorter if I participated in accident simulations with my team. However, the circumstances in which I practice are different from yours. I do not have a team. In my institution there are seven surgeons, 30 scrub nurses, 12 anesthetists and 13 perfusionists (they also cover our busy liver transplant program, VAD program and ECMO), and at any given time you can be working with any of these people so there are few hundred permutations of who can comprise the OR team. I have a
 case on Monday and no idea who I will work with. I do not, as I suspect you and many of the private surgeons amongst us may, have my usual anesthestist(s), scrub nurse(s) or perfusionist(s). Of course on many occasion one has a student like you do to. I have difficulty introducing things the way you do. For example I would like to retrograde prime but it is difficult getting that going as can only do it with the right combination of anesthesiologist and perfusionist - as you say skill sets differ.

You must also not interpret what I say as representative of myself, my practice or my knowledge. I did the FRCS Cardiothoracic Exam which has a 30 minute oral exam on Basic Sciences and generally includes grilling on many subjects of what I see as irrelevant minutiae, some of which are CPB related. This exam had a 30% pass rate. However that I went through a system does not mean that is what those who follow me should do. It may be fine in the UK to delve into detail, because we trained for six years, however in the US where surgeons train for 2 years in many programs, they do not have the luxury of time to learn in the depth that you did, the details of how a plane is built and how its various parts work, how an airport works, what air traffic controllers do etc (using Ben's analogy). Of course some introduction is necessary but such depth as many seem to imply in this thread is probably excessive.

Another mistake I think you must avoid is expecting others to be like you. I know this because my father also taught surgery in a third world country and when I hear you talk, I hear him talk - you have to be the perfusionist, nurse, anesthetist, etc etc. All on this board know that your level of theoretical knowledge surpasses that of probably everyone else here. It makes you a better doctor and a thinker, as you say, to know what you do. However, the converse does not apply i.e. it is not necessary to know as much as do to be a good doctor or excellent surgeon. You shoulg not therefore impose your own standards on others. I suspect that many of your students would know the answers to the stuff on Mike's list - the difference between ph and alpha stat, physiology of bubble oxygenators etc but when asked the practical questions on Tom Martin's list they will have no clue or when asked what to do when they face Roberto's dissection scenario will have no
 clue. I know this because I have trained with several MCh graduates who focused so much on theory, and knew so much theory, but could not translate much to practice. We must focus on teaching residents Applied Basic Science i.e. applying basic science to clinical practice, and not theory for theory's sake. We are over 50 years on - it is no more necessary to know details of what Gibbon did, than it is to know the precise description Harvey made of the circulation or Carrel did for anastomosis - also key landmark points in the evolution of cardiac surgery.  I doubt Roberto would agree with you in ascribing his great save to 'thorough knowledge of perfusion physiology' but will wait to hear from him - he may have such knowledge but that is not the reason he was able to make such a save.

I agree with your concerns about minimalisation of knowledge and say same to myself - we must not pretend cardiac surgery is easy and can be accomplished without investment in knowledge.  However we have to be realistic and practical in what we require of our residents. This is 2007 - a lot has changed even since Ed's 1987 (it is two decades ago Ed!). The days of residents trembling like he did because big Karp was in town are long gone. Now we must breast-feed and nurture our residents or there will be no one to operate on us when we are 82. Please don't frighten them away with too much knowledge! CT residents in 2007 are delicate fragile structures, and made of a different stuff from Gibbon, Frater, Ed or Prasanna, or even myself and Michael who are very recent graduates. With each era, things change and we feel our successors are not living to the requirements, rigours or standards we did; as I am sure Gibbon would say same of Frater, who would say
 same of Martin who would say same of Ed who would say same of me and I say same of the current trainees. It is an evolution and we must allow the residents to evolve with time and not visit the sins of the fathers on the son.

Ani

> Date: Sat, 11 Aug 2007 07:33:49 +0530> From: prasannasimha at gmail.com> To: OpenHeart-L at lists.hsforum.com> Subject: Re: [HSF] CPB - what the surgeon needs to know.> CC: > > Ani,> It may be fine to just "order around" but that is because you are > sitting in an academic center with back up on backup of varying levels > of skill sets of perfusionist's. Unfortunately you will see varying > skill levels of both perfusionist's and surgeons. If you need to change > one variable in your perfusion prescription is it a crime to know how it > will potentially vary your surgical technique ? Ignorance is bliss but > knowledge can be power. The life time accumulated experience for most > perfusion accidents is low (and hopefully remains low) that when an > actual accident occurs the team may not have had sufficient experience > to deal with the complication in a swift coordinated tandem manner. Did > you ever consider that a surgical team and a perfusion team have to
 > actually "practice" accident simulations so that they can efficiently > work together. Take Roberto's example - thorough knowledge of perfusion > physiology allowed him to compensate for a surgical -perfusion accident. > The skill and knowledge of a surgeon compensated for the novice > perfusionist (and let me assure you the reverse also happens) allowed > the resolution of a potentially disastrous complication.> I have personally not "actively" run the pump on a live case for > probably over a decade but I still am the teaching faculty for the > perfusion course (I do not think that any time in the discourse and > discussion was it ever mentioned that the surgeon needs to run the pump > ). All new trainee perfusionist's do their initial cases with me and > along with a senior perfusionist and I can assure you that my > perfusionist's are of excellent quality and quickly pick up new things.> Let me assure you that having a new student on the pump is
 not as > simple as it seems and is equally stressful to both the accompanying > perfusionist and the surgeon. I am very proud of my students who have > gone to various institutes and have done very well. Training them, I > realize how insulated many surgeons are wrt knowledge of perfusion. > Perfusion can be a "mystical tool" or it can be an excellent thing that > can be manipulated by both a knowledgeable surgeon and perfusionist to > get a better result.> Pray tell me (and I am cut and pasting from the previous posts) why > should you feel amused about> > Surgeons role in managing perfusion disasters including backup plans> > While this is not a "how to run the pump" > answer, it lets the surgeons know that what they do at the table does effect us > at the pump and vice versa. Instead of telling us to deal with it, > > > best practices for blood conservation in CPB cases > > and so on and so forth ?> > > Minimalism of required knowledge may look
 tempting especially on a > debating floor but if carried to an extreme will result in a zero (or > even a negative) asymptote.> Prasanna> Ani Anyanwu wrote:> > I find this list more and more amusing as it goes on.> > > > The topic is "what the surgeon needs to know"> > > > If the surgeon needed to know all the things so far on this list I feel sorry for the poor patients because I suspect if you poll practising surgeons - even poll HSF list members - few can explain the various concepts and topics listed thus far.> > > > This is the 21st century. The surgeon does not NEED to know all these things. For those of us who know it or have a special interest in perfusion, it is a good thing and it should be applauded, but for the surgeon training in the 21st century it is not necessary to know much more than what Dr Martin included in his list to practice good cardiac surgery. If one practices in environments like prassana's or erdinc there is a different
 requirement but in most established health systems, perfusion is now a serious discipline which is well separate from cardiac surgery. At least in the US, in 2007 it is unrealistic and unnecessary to expect the cardiac surgical resident to know how to run the pump.> > > > Ani> >> >> >> > > >> Subject: RE: [HSF] CPB - what the surgeon needs to know.> Date: Fri, 10 Aug 2007 10:21:26 -0400> From: Michael.Crittenden at va.gov> To: OpenHeart-L at lists.hsforum.com> CC: > > > By hemofiltration I presume you are referring to CUF (and its variants> > DUF, ZBUF) versus MUF> Yes> > I agree with you regarding the need to teach bubbler "physiology" for> historical reasons.> > Mike> > -----Original Message-----> From: openheart-l-bounces at lists.hsforum.com> [mailto:openheart-l-bounces at lists.hsforum.com] On Behalf Of psimha> Sent: Thursday, August 09, 2007 9:08 PM> To: OpenHeart-L at lists.hsforum.com> Subject: Re: [HSF] CPB - what the surgeon needs to know.> > I think that in
 the present day there are no manufacturers of bubble > oxygenators. I still teach them to Perfusionists for two reasons - > Historical and also to illustrate principles of gas exchange and > oxygenator design. (In fact the defunct Polystan Rygg Kvysgaard > oxygenator was wonderful to demonstrate how engineering can solve many > biological requirements !!)> By hemofiltration I presume you are referring to CUF (and its variants > DUF, ZBUF) versus MUF.> Prasanna> Crittenden, Michael wrote:> > 1--alpha stat vs pH stat> > 2--optimal pressure during cpb> > 3--pulsatile vs non pulsatile> > 4--bubblers vs membranes> > 5--hemofiltration routine vs special cases> > 6--advantages and disadvantages of different priming solutions and> > additives> > 7--arterial and venous cannulate sizes as related to body size and> > desired flow rate> >> > -----Original Message-----> > From: openheart-l-bounces at lists.hsforum.com> > [mailto:openheart-l-bounces at lists.hsforum.com]
 On Behalf Of psimha> > Sent: Wednesday, August 08, 2007 9:44 PM> > To: OpenHeart-L at lists.hsforum.com> > Subject: [HSF] CPB - what the surgeon needs to know.> >> > Dear Forum members,> > I am to speak at a CME for students that is held yearly and sponsored> by> >> > our National association. My topic is> > "CPB - what the surgeon needs to know."> > I would like to poll the members (and especially the students who lurk> > > on the list and the consultants who recruit "fresh" consultants )> > What do you really want to know or be updated upon?> >> > Apart from the basics (Seeing the last few discussions) -> >> > Vacuum assist needs to be touched on. What else ? probably> > Retrograde priming,> > Surgeons role in managing perfusion disasters including backup plans.> > How to give a perfusion prescription ?> > Heparinless bypass> >> >> > Obviously I will have a limitation wrt time so a poll would probably> > > highlight what students want to know and what
 consultants urgently> want > > their traineesand expect their new graduates to know on a practical> > basis.> > I would really appreciate the information as it would make my talk> more > > relevant .> >> > Prasanna> > _______________________________________________> > OpenHeart-L mailing list> >> > Send postings to:> > OpenHeart-L at lists.hsforum.com> >> > To UNSUBSCRIBE, to CHANGE email address, or to view archives:> > http://mmp.cjp.com/mailman/listinfo/openheart-l> >> > All messages transmitted by the OpenHeart-L are subject to the> policies> > and > > disclaimers posted at:> > http://www.hsforum.com/listdisclaim> > -----------------------------------------> > _______________________________________________> > OpenHeart-L mailing list> >> > Send postings to:> > OpenHeart-L at lists.hsforum.com> >> > To UNSUBSCRIBE, to CHANGE email address, or to view archives:> > http://mmp.cjp.com/mailman/listinfo/openheart-l> >> > All messages transmitted by the
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