On CPB- Heparin Protocol Survey

Clot in Fibrin

Clot in Fibrin2

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Editor’s Note:

I received a note from a perfusionist the other day regarding heparin administration, and how it has become regulated at their institution. 

It was significant enough- in terms of it’s implications of our ability to manage patients on bypass for me to pass on the concern, and as well- develop a survey to perhaps get a global picture of how anti-coagulation is managed in the rest of the perfusion universe- as well as WHO manages it.

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Wiley Coyote

“Dear Circuit Surfers,

I am writing to express a concern I have at a new protocol the chief pharmacist at out institution is implementing regarding the on-bypass administration of heparin.

This gentleman has taken it upon himself to conduct a surreptitious study of each perfusionists’ heparin administration for the past two years.

According to him, we are over heparinizing our patients because we exceed a 25 units/kg/hour threshold that he sites from a study he uncovered somewhere.  If you do the math, by his standards we exceed our “heparin limit” if for example we gave more than 5,000 units to a 75 kg patient in a 3 hour period of time.  That represents an arbitrarily limit of 1.7 cc of heparin per hour. 

It fails to take into account any (see below set of criteria) mitigating clinical circumstances, and represents a line drawn in the sand of compliance or non-compliance.  So administrative intimidation becomes a factor here- when PowerPoint bar graphs are thrown out to isolate the perfusionists deemed “more” or “less” compliant.

I have not seen the study, but our loading dose for patients is Hepcon based , as well as a 480 second target before engaging CPB. 

In my opinion, taking heparin totals as the primary argument on whether or not we are over heparinizing our patients, ignores several key factors, including the following:

  • Heparin resistance
  • Heparin half-life
  • Core temperature
  • Hemodilution
  • The point in the operation where the ACT falls below acceptable thresholds
  • Factor depletion
  • A myriad of potential coexisting disease states
  • Muscle versus fat mass of patient
  • A controlled and easily anticipated protamine administration response to heparin rebound in the ICU

I want to ask the rest of the perfusion community the following questions:

  • How is your loading dose determined?
  • Who is in charge of your heparin protocols?
  • Who decides when and how much more heparin is to be given?
  • Do you need to “ask permission” to maintain a safe state of anticoagulation?
  • What is your threshold for administering more heparin?
  • Do you use a “fixed dose” or do you adjust to patient clinical parameters?

Thank you very much in advance for your input and advice!”

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So anyway,

I developed a survey as result of this question– because I was frankly shocked to hear that a pharmacist was involved in dictating perfusion practice- let alone the suggestion that as a result- it seems to have led to an adversarial environment that effectively punishes, brands, or isolates perfusionists for the amount of heparin they end up giving in order to safely keep patients on bypass without clotting off their circuit.  It is the first I have heard of it- in the more than 30 institutions I have been privileged to pump at.

I guess my question is- What happens when the pump clots off?  That is clearly a misadventure that would be almost impossible to overcome in time to preserve the patient’s life, and as well- is totally avoidable.

Heparin is obviously easily reversed with protamine- and clearly, heparin rebound is no “recently encountered medical epiphany” and should be duly anticipated and treated, prior to it becoming an issue where the patient is rushed back to the OR for postop bleeding problems.  That is Basics in heart surgery 101 in my opinion.

The key inference here is not who determines heparin administration- that obviously falls under the prescriptive authority denoted by the physicians that we work with (MDA/Surgeon).  We give it- under their auspices- in conjunction with our own clinical judgement.  There must always be a conversation, and I believe that we as perfusionists do not omit or ignore that premise.

But show me a perfusionist who is intimidated to the point of ignoring the obvious- not giving heparin when it is clearly indicated, and I will show you a poor outcome or a dead patient.

So please if you will?

Click the link below to fill out a very brief survey?

I think it would benefit us all to see where we stand as a professional group on this issue.

Thanks 🙂

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Perfusionists, Anesthesiologists, and Surgeons please respond

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Results (real time as they come in)


Click image to see responses

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From Dr. Bill Novick, Pediatric Heart Surgeon, Founder & CEO of ICHF (International Children’s Heart Foundation)


We load with 300-450 units of heparin/kg, and give additional heparin if necessary to achieve an ACT of >480s. If the ACT is not >400 after 800 units/kg dosing, we blood bank for FFP (esp if patient previously on heparin) to treat AT3 deficiency. While on pump we keep the ACT >480 seconds. In fact I routinely keep it >550s as I have been informed by our anesthesiologists that newer studies have shown coagulation factor consumption even at 480 seconds, but not in the 550-650sec range. Part of heparinization is to prevent clot from forming, but also to prevent fibrin formation as well as protect the coat factors- so that normal clotting can occur later. Studies showing inadequate heparinization also show greater post-op bleeding and blood product usage. You may wish to present this to pharmacy as well. Even if we are about to come off pump and the ACT is marginal we give some heparin (3-5 K units) so that if we are keeping up with vents/suckers etc., we have a margin of safety.

The methods of heparin management vary from institution-to-institution and in some instances from anesthetist-to-anesthetist. The first rule in heparin management is adequacy of anticoagulation, patient safety and survival by avoiding a coagulated circuit is utmost in avoidance. No perfusionist should “ever” be at risk for avoiding this adverse event. I have seen one patient who had protein C&S deficiency and adversely reacted to antifibrinolytics, hope to never experience this again. The variance in heparin processing and manufacturing coupled with inadequate technology to assess is creating nightmares at various intervals. Patient-specific monitoring is critical in my opinion, we must adapt to this concept and utilize multimodal analyze and monitor.

They work. Our end point is no clot evidenced in the CPB circuit.

there never has been clot in the circuit.

Pharmacy need some education.

In Europe this would not be a possibility .

I do not think pharmacy has a place.  They are generally by the text book and don’t know what the OR is like(evident by lack of speed when you order a drug).  I am a firm believer that perfusionists should have more discussion and affiliation with the AABB.  We should pride ourselves on being hematologists as well as perfusionists and should seek all possible resources.  STS and AABB should be on the forefront of blood usage, blood conservation and anticoagulation protocols.

For adjustment of heparin dosage during bypass we use the Formula:{550 (desired ACT)- actual ACT result(if <480) x 0.5 x wt.(kg)}

With this protocol and formula from the 3 centers I’ve been, patients are well and no result whatsoever defined as “”heparin overdosing.

Perfusionist discusses ACT result with surgeon prior to initiating CPB.  Perfusionist manages all subsequent heparin doses on CPB.

Perfusionist discusses ACT result with surgeon prior to initiating CPB.  Perfusionist manages all subsequent heparin doses on CPB.

we give 3.4 IU/kg and usually achieve an ACT >410.  If we don’t achieve an adequate ACT we go straight to Thrombate.

We give 300/kg in adults, 400/kg in neonates/paeds.  100/kg (up to 5000 iu) is in the pump. We canulate after 3 mins (preferably with an ACT, but it’s not in the protocols). Pump suckers on at 250, on cpb at 350 and run above 400 on the pump. Our top-up dose is 100/kg for ACTs less than 400, but would give more is starting rewarming/filtering

We give 300units/kg pre-bypass.  Check ACT to be at least 430sec. If ACT falls below 430 recheck in 10 min and if it is still low give 10K standard to our protocol.

all this depend from a lot of things type of procedure tem

I would suggest that the ACT for iniation of CPB be a littkle higher..min 350 seconds….at the low range..ideally 400 s.

We give 300mg/kg loading dose.We cannulate at 300 sec and go on at 400 sec.We take a ACT with 1st ABG  after 10min on CPB.If act less than 400 give 5k heparin. Very simple.KISS

We give 500 units per kilogram and estimate a concentration on CPB of 3.5 units/ml. Protamine is 60% of the total heparin. Additional heparin is given to maintain ACT>400 sec

Our standard ped. dose in the pump is 1000iu of heparin, regardless of size. If an extremely large patient, we may put 3000-5000 in the prime.

300U/kg loading dose, unless pt. on heparin pre-op and baseline ACT is elevelated, to achieve a target ACT of 480, but miniumum 400 sec. ACT for CPB institution.  Heparin boluses given duringCPB to maintain ACT 480 sec.

HMS. Normally 300-400u/kg. 100u/kg pump. Go on at 2x baseline.. Check 10 min after initiation.  Then every 45min. Redose with act<480. 100u/kg.

We always wait untill ACT is at least 400 before the suckers are turned on. Only go on bypass before ACT is 480 if it is an emergency.

400u/kg initial dose,  10,000u in pump,  10,000u every 90 minutes regardless of ACT’s.  Additional heparin given if ACTs done meet 480 seconds.

Protocol – Dose with HMS recommendations throughout case.

Suckers/RAP/VAP at 300 sec.

Go on with ACT > 400 or HepCon >60% of target.

HMS every 30 minutes or more as clinically required.

We use the HMS Plus. We base our dose on the HDR. It is set for 300units/kg with a targer ACT of 500.  We adhere to this protocol exclusively. This protocol was decided between my surgeon and myself.  I rarely run ACT’s during the pump run. There are so many factors that affect ACT’s. I run heparin assays every 15 minutes and if more heparin is required to get back to my HDR required dose, then i administer it. We allow our patients to drift, unless surgeon deems it necessary to cool. Upon rewarming, what little we have to do, i monitor heparin assays every 10 mins, since the heprin will be consumed more upon warming. Our protamine dose is based on the last heparin assay run prior to coming off bypass. This has worked great for us. We have found that we have not used as much heparin and we use less protamine. Pharmacy loves us.  Our patients are not “wet” when closing the chest, rarely see any heparin rebound.  We also do routine coags with the post protamine heparin assay and ACT. Alomst every time, our coags are within normal limits, not rrequiring any FFP, Platelets etc….If you would like to discuss futher, email me @ [email protected] Hope this helps and you get this worked out.

300/kg, 2u/cc prime, maintain 400S until ready to come off.  What is your ACT at end of MUF???  No one checks.  Much lower and yet pump suckers and Transfusion.  Why are you not worried about this time?

We do roughly the same when using Hemochron.  When using the HMS system we use a concentration on 350/kg and then use the concentration levels, as well as ACT and point we are at in the case, in consideration prior to treating.

HDR on HMS. Always give at least 300u/kg to patient. Maintain hep conc. during bypass & ACT at least 480.

give 350/kg initially, 10000units in pump, cannulate when act is at least double baseline….Act every 15-20 minutesm additional heparin given if act falls below 425

I have no hard and fast rules. For example, I will run a continuous high concentration heparin drip in cases with massive blood loss (and accompanying blood/product administration).   In my 35 plus years I have seen 4 circuits either partially or completely clot off, it is very ugly. These were all bizarre out of the ordinary cases.

Due to aging patient population, more drugs overall that affect coag, and the individualized response I have seen from 30 years of practice-we use the Hepcon HMS: give dose per u/kg/ml per device, on CPB w/ ACT over 480 or above calculated dose response. ACT alternating w/ Hepcon on CPB giving required dose provided by Hepcon, ACT over 480 on CPB, protamine calculated by HEPcon prior to weaning off CPB. 10ku in pump prime, adjusted for RAP.


load 400u/kg for under 10 kg

load 300u/kg for over 10kg

various amounts in pump

We give 400/kg initially.

ACT checked every 30 minutes

500 units added if needed until desired result reached.

We always draw a base line (usually 120 +/- 20 sec), give 300 u/kg heparin bolus and 2 u/ml of prime volume.  Cannulation can be initiated 2 minutes after heparin administration. Wait until ACT is 3X baseline or greater.before starting CPB.

Drawn ACT every 10-15 minutes.  We use the MaxACT tube.  Seems to work the best for us and uses less blood than other tubes. If ACT drops below 400 seconds, will redose with 1/2 bolus dose, but if CPB termination is iminent (15 minutes) we don’t re-bolus.  15 minutes prior to CPB termination, protamine reversal dose is titrated.

Comment: pharmasists usually calculate heparin dosages based on partial anticoagulation for artificial valves or embolic stroke patients.  They do not usually calculate dosages based on full anticoagulation for a patient who is on CPB where the coagulation system is massively stimulated by a large artifical surface and the coagulation system is hemodiluted.

We also give 400/kg initially and 10,000 in the pump prime.  We cannulate after 3 minutes and wait until ACT is > 400 (unless emergency or directed to do so by MD).  We check ACT every 30 min. and perfusionist gives heparin based on result (5,000-10,000 units).

We give 4 to 500/kg  suckers on at act of 400 if need be and we stop suckers at test dose of protamine.

Hepcon to determine dose, combination of judgment based on situation and hep con results for additional dosing.

Initial dose is 300 units/kg, act target >480.  Empirically add 10k units to pump, more if act is borderline and anesthesia will not have ample time for dosage and follow up act before initiating cpb.   Add heparin as needed to maintain act >480. Will allow act to drop below this threshold only in the last few minutes (10 minutes) of cpb. Oftentimes, due to heparin resistance, reduction in efficacy of heparin, and other clinical factors, or heparin doses exceed 400 units/kg, and our utilization of FFP to achieve adequate anti-coagulation has risen drastically in the last 1-2 years.

Due to the myriad of factors needed to manage heparin in a patient that are not apparent to pharmacists, heparin dosing is not a clear cut regimen that will apply to any sizable patient population in cardiac surgery. The decisional process for heparin is easy, when in doubt, give more. Heparin is reversible, clots are not.

We give 3 mg per kg initially 1 mg per kg in the pump and we cannulate at 250 seconds and go on bypass at 400..ACT checked every 1 hr and depending up on the ACT and where we are in the procedure we add heparin

We give 400/kg initially, and 100/kg in the pump. We cannulate at 300 seconds and go on at >400. ACT checked after 30 minutes  and then we give 100/kg depending upon ACT < 400  alternating with fixed dose100/kg after another 30 minutes regardless where we are in the procedure.