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Portland Diabetes Project
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Portland Diabetes Project Frequently Asked Questions
The Portland Protocol history
Patient population and guidelines for use
Administrative and nursing issues
Checking glucose levels: frequency and methods?
Reference articles and abstracts
Portland Protocol – History
What is The Portland Protocol?
A. The Portland Protocol is a tight perioperative glucose control regimen using continuous insulin infusion in diabetic patients undergoing open heart surgery.
What are the origins of tight glycemic control protocols?
A. Tight glycemic control protocols started because of the direct relationships that have been discovered between hyperglycemia and adverse in-hospital outcomes. Increasing hyperglycemia has been independently shown to cause increased infection rates, increased mortality in CABG patients, and increased length of stay. Conversely, tight glycemic control protocols have been shown to independently reduce in-hospital mortality, LOS, and infection rates.
The Portland Diabetic Project was the first to elucidate these findings with publications starting in 1995. Other publications from our center followed in 1997, 1999, 2000 and 2003. Corroborating data from other centers began to appear in 2000. Since then there has been an explosion of interest in tight glycemic control. There are currently several glycemic control protocols available. Ours, known as "The Portland Protocol," has been in use since 1992. Over the past 14 years, it has been repeatedly modified and honed to provide what we believe is the tightest, most efficient, and safest tight glycemic control of any protocol available. The incidence of hypoglycemia < 60="" mg/dl="" with="" our="" 70="" –="" 110="" mg/dl="" protocol="" is="" 1.5="" percent="" (safety="" index),="" while="" 91="" percent="" of="" the="" patients="" are="" within="" target="" range="" within="" three="" hours="" of="" starting="" the="" protocol="" (efficiency="" />
Who is adopting The Portland Protocol?
A. We have had more than 200 inquiries regarding the specifics of starting up our protocol, from centers including: The New England Cardiovascular Consortium; The Ottawa Hospital in Ottawa, Ontario, Canada; Oschner Clinic; Palo Alto VAH; Jewish Hospital in Louisville, KY; Providence Hospital in Seattle; King Faisal Specialist Hospital and Research Centre in Riyadh, Saudi Arabia; West Florida Regional Medical Center; Methodist Hospital in Peoria, IL; TriHealth Systems in Cincinnati; Dartmouth-Hitchcock Medical Center in Lebanon, NH; Suburban Hospital, MD (NIH); and many more.
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II. General Information
Can results be achieved in the nondiabetic population using continuous insulin infusion?
A. Yes – glucose control can be, and should be achieved in the hyperglycemic, but nondiabetic patient population. However, because the nondiabetic population does not have as high a risk of infection, mortality and LOS, the results seen in a non-diabetic population are not as dramatic. The biochemical mechanisms at play behind these outcomes improvements are universal and apply to the nondiabetic population of patients as well. However, the outcomes improvements are real; they just cannot be proven to be statistically significant at this point.
Is there any reason a patient wouldn't be eligible for the tight glycemic control protocol? Is there a checklist that you use for determining eligibility?
A. No reason that we can think of at this point, because the current data strongly suggests that if the patient has hyperglycemia, he/she should be treated.
Has tight glycemic control been examined in pediatric populations, particularly after neonatal and infant congenital heart surgery?
A. We use tight glycemic control in our pediatric cardiac surgery population. Outcomes changes have not yet been found to be significant. However, we feel control is important. We believe it is being used extensively in pediatric ICUs and is definitely used in neonatal ICUs. We do not have a specific protocol that is different for pediatric patients; others might.
Regarding the biochemical mechanisms of action related to clinical outcomes. I would like to get a clear picture of what is happening to the body and why glucose gets out of control. I have tried to explain that the stresses on the body from these procedures are affecting the glucose values and they should not be used to diagnose the patient as diabetic, but used as part of the glycemic protocol until such a time that the patient gets back in control or until discharged, when proper testing for diabetes should be performed.
A. Stress hyperglycemia is real. The situation usually only exists for the first 24-72 hours post-surgically. I have seen it persist in the ICU population for a week. I have occasionally seen it persist on the floor for 96 hours (4 days).
These patients are not diabetic; rather they have abnormal insulin response to stress, which does not resolve in a short period of time. Some have called them "borderline" diabetics. We always wait until the patient is out of the unit and at least three days from surgery and still requiring intravenous insulin before we give them the diagnosis of “diabetes”. In so doing, we obtain an endocrine consult and let them decide (I am a CT surgeon, not an endocrinologist). Half of the time the endocrinologist determines that they are not truly diabetic. Endocrinologists should know well the biochemical mechanisms involved in the surgical stress scenario. It is important to treat hyperglycemia, but not all hyperglycemia occurs in diabetic patients only. It is interesting to note that our nurses and clinicians are more prone to back off on hyperglycemic control of non-DM patients. As such, many non-DM patients come off the drip early and are not kept on it for three days. Interestingly, we have seen sternal wound infections in non-DM patients who were "allowed" to become hyperglycemic (hyperglycemic ignorance). In addition, the diabetic CABG mortality in our institution has been reduced to a rate BELOW that of the no diabetic population with the use of prolonged tight glycemic control – a feat unequalled elsewhere in the cardiac surgery world.
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III. Patient Population and Guidelines for Use
How long should The Portland Protocol be used and should it be used in all diabetic heart surgery patients?
A. It depends on what kind of outcome modification you want to produce.
For improving rates of mediastinitis:
In all diabetic median sternotomy patients, for prevention of blood glucose infection, our current results show that it is important, in the ICU and on the floor at least until the morning of the third postoperative day. This is important for valve patients as well as CABG. With decreases in the time course of use of the insulin drip (e.g. if you are using it only in the ICU) there will be incremental increases in the infection rate (assuming tight glucose control; less than 175 mg/dl is the goal for infection prevention). Insulin drip in the OR through the morning of the third postoperative day – less than 0.3 percent mediastinitis; OR and ICU 0.8 – 1 percent mediastinitis; OR only 2 percent; None - 2.5 percent.
Only important in ischemic patients, does not alter survival in non-ischemic valve patients. Should be used through the ICU period (no matter how long the patient is in the ICU and at least to the morning of the 3rd POD as well.
For either outcome:
The use of insulin with no regard to serum glucose levels is of no proven benefit to the patient and may be detrimental! Hyperinsulinemia in the face of hyperglycemia activates inflammatory mediators that induce heart failure and arrythmias. Glucose must be monitored and controlled at less than 175 mg/dl while patients are on an insulin infusion.
Is The Portland Protocol specific for diabetic cardiac surgery patients or has it been used for non-cardiac surgery patients as well?
A. It is used in our ICU and CCU for all diabetic patients with high glucose levels. It is also used on our surgical floors and is being rolled out to the medical floors in 2005 as well.
When are the patients placed on an insulin drip?
A. Depends on the target range chosen. For a target range of 70 –110, diabetic patients are placed on an insulin drip at the first blood glucose (blood sugar) of >125 mg/dl anytime intraoperatively or postoperatively. Diabetics who happen to be admitted to the hospital with BG levels > 200 are started on the insulin infusion on admission to achieve control prior to going to the OR. For previously non-diagnosed patients with elevated blood glucose, at the second blood glucose of 150 mg/dl.
How long should one continue The Portland Protocol?
A. The protocol should be continued until the morning of the third postoperative day.
How long is the drip continued?
A. Duration of insulin infusion is as important as target ranfe in determining outcomes. Continue the drip until the glucose is consistently within the target range (currently less than 110 mg/dl) off of the drip or until 7 a.m. on the third postoperative day for surgical patients who have transferred out of the ICU. Patients who remain in the ICU for longer than 3 PODs should remain on the drip as long as they are in the intensive care unit. If one chooses not to employ insulin infusions according to thesetemporal guidelines – e.g. to use them only in the ICU but not on the floor until the 3rd POD; or to use them only for 3 PODs in patients who stay in the ICU longer than 3 PODs – then that institution may reduce the infection and mortality rates somewhat, but it is unlikely that they will “normalize” the diabetic infection and mortality rates to that of the nondiabetic population.
Who gets started on The Portland Protocol and when? Is every diabetic patient supposed to be started on it post-op even if it wasn’t started in the OR? Do you wait to see if your diabetic patient develops elevated blood sugars, and then start it?
A. Any diabetic patient who has a single blood glucose above 125 mg/dl is started on The Portland Protocol at the time the first blood glucose is seen above 125 mg/dl in the intra- or postoperative period. If a patient is admitted to the hospital preoperatively and has a glucose >200 mg/dl, s/he should be started on the protocol preoperatively. These guidelines are necessary to affect the strict control required to reduce length of stay, infection and mortality rates.
In non-diabetic patients (6 percent of our series represents patients with diabetes undiagnosed at the time of admission) we start the protocol after one blood glucose level > 150 mg/dl.
The Portland Protocol is used only as a starting guide in the OR, where the anesthesiologist uses IV insulin boluses and initiates and maintains a drip which is titrated as he/she wishes to keep the blood glucose within the set target range (currently 70-110 mg/dl). In reality, this can obviously also be done in the post-op period by experienced ICU nurses who are comfortable with and capable of titrating drips to maintain set parameters. Those nurses who do not feel comfortable titrating “ad lib” usually use The Portland Protocol as written, knowing that the goal is to rapidly (within 3 hours) get the blood glucose into the target range and keep it there.
Do you do anything with the patient who is not a known diabetic but still has a blood glucose over 150 mg/dl during the surgery?
A. Yes, we treat all non-diagnosed patients with blood glucose greater than 150 mg/dl with insulin infusions as well. This initiation target may be lowered in the future to match that of the diabetic population (125 mg/dl) as more outcomes data become available.
I am a RN, and I am interested in the aggressive diabetic management of CABG patients. For example, what is the accepted range of blood glucose levels that will optimally help to prevent the complications of wound infection? What kind of sliding scale orders are being written? I have noticed that several of our patients continue to have sugars 250 mg/dl in the postoperative period. Typically, our postop CABG patients are managed by a sliding scale. They are placed on an insulin drip only if their sugars reach 400 or above. Is this a common practice?
A. This (sliding scale subcutaneous insulin) may be common at other centers, but as our work is becoming more widely recognized and is being repeatedly confirmed by others, this practice is ceasing. A continuous insulin infusion has become the standard of care. See the current guidelines for open-heart surgery published jointly by the ACC and AHA. Insulin drips are now part of the recommended guidelines for DM care. (see
, pgs. 11 and 37. )
Our original publications looked at sternal wound infection and our data has proven that the infection rates come down when blood glucose is controlled to less than 175 mg/dl using an insulin drip. The biochemistry behind this “inflection point” has to do with impaired immune function at BG levels above 180 mg/dl (10mmol). It is important to note that a continuous infusion method is more effective at delivering insulin to the cellular level where it redirects myocardial metabolism away from the use of free fatty acids and enhances oxidative glycolysis. This results in improved mortality outcomes, which are reflected in our data. The problem with using a sliding scale is you chase the sugar after it goes up. Blood sugar is much easier to manage when on a drip. The anesthesiologists manage the blood sugar in the OR.
Should the infusion be maintained at the same rate when blood glucose is 101-150 mg/dl but is higher than the last test? Is it reasonable to increase the infusion by 0.5 units/hour for increases 10 percent over last test and maintain the same rate for increases?
A. Yes it is reasonable to titrate the drip when the BG is within the target range if one sees a consistently rising or a consistently falling BG level. This is handled in the current order set by the statement “titrate the drip” to maintain BG within the target range.
Can I just use The Portland Protocol in the ICU and not for two full days?
A. You can, but you should not expect the rates of infection and mortality to be normalized to that of the nondiabetic population if the protocol is not utilized until the morning of the third postoperative day. It will be reduced for sure, but one will not affect the complete dramatic results we have seen. There is both a physiologic and clinical basis for the rationale of running the drip until the third postoperative day.
Could you point to any peer-reviewed clinical guidelines that incorporate tight glycemic control in the ICU?
A. In 2004 the ACE and the AACE had a consensus conference on inpatient diabetes and metabolic control. This was held in December in Washington, D.C., and I was privileged to speak at the meeting and to participate in the task force. The recommendations of the task force were published in Endocrine Practice, March/April 2004 edition, volume 10, supplement 2. The guidelines are published on page 4. The summary of the Portland Diabetic Project is on page 21. The entire journal is a primer for in-hospital glucose control.
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IV. Administrative and Nursing Issues
What would be your advice for re-educating doctors and nurses to the lower critical values demanded by The Portland Protocol? What worked for your group in establishing institution-wide “buy-in”?
A. We have found that by empowering the nurses, physicians, and administrators with our data on mortality savings, length of stay savings, infection savings, and direct cost savings, one achieves the necessary buy-in. You will still need a multidisciplinary team to implement the tight glycemic control protocol as it crosses many disciplines from ICU nurses, anesthesiologists, floor nurses, and diabetes educators. What worked for us was that we started an IRB sanctioned research project in 1992 that included an experienced nurse (Jeanne Zerr, RN, MBA), an endocrinologist (Steve Bookin, M.D.), and myself. Once we started demonstrating that using the Portland Protocol was able to reduce infection by 66 percent, mortality by 60 percent, and LOS by 1.5 days, everyone started to buy into the project.
What other administrative issues are involved in getting the buy-in for using an insulin protocol in postoperative patients?
A. Again, besides the M.D. buy-in to the concept, the key issues are: nursing buy-in, knowing that infection rate and mortality will be improved; and administrative buy-in, as it will cost slightly more than q 4 hour SQ sliding scale insulin ($138/patient in our analysis) but will save money (conservatively $680 / patient) over the long-term with wound infection, LOS and mortality improvements.
Are there any difficulties in starting The Portland Protocol, e.g. nursing anxiety, insulin overdose, etc.? Has anyone tried modifying the duration of therapy to be longer or shorter than 48 hours?
A. With regards to implementation, RN anxiety is probably the biggest factor as it is an RN-run protocol and nurses are not used to having insulin drips running on patients with high blood glucose.
From a nursing point of view, how did you overcome the difficulty of calculating percentages in The Portland Protocol?
A. We used to use percentage decreases in BG levels to titrate the insulin infusion, but due to feedback from other centers and our own, we have modified the protocols to be devoid of percentages.
Regarding telemetry staffing: What would you identify as an ideal ratio for safely monitoring diabetic patients, and how do you determine this ratio?
A. During the day (7 a.m. to 3 p.m.), the ratio for all patients including The Portland Protocol patients is often 4:1. I would say that this is the ideal ratio for nurses taking care of insulin infusion on the floor, but it may not be practical. In evenings (3-11 p.m.) the ratio is 5:1, and nights (11 p.m. to 7 a.m.), the ratio is 7:1. At this point they do not put patients in a “step-down” (which has a ratio of 3:1). They did this at the start of the protocol on the floor until they were comfortable. I can’t say whether or not these numbers were “ideal” but I know they work comfortably for the nurses. Remember, by the time the patient arrives on the floor 24 hours after surgery, the drip is pretty much constant and requires only minor titration. We let the nurses themselves work out the coverage ratios. They have to completely buy in to the concept, as they are the ones who run the protocol.
Could you provide the cost benefit analysis, i.e. how much more expensive it is to implement IV insulin therapy compared to SQI therapy? This has to be balanced against the obvious gains from less infection.
A. There is a preliminary cost-benefit analysis published in Furnary, A.P. Endocrine Practice, Volume 10, (supplement 2) March/April, pp. 21-33, 2004.
Is an IRB Protocol necessary for The Portland Protocol?
A. We have no current IRB protocol at this point because aggressive control of perioperative hyperglycemia by continuous insulin infusion is a Case IIa recommendation by the ACC and AHA, web site referencewww.acc.org/clinical/guidelines/cabg/index.pdf (pgs. 11 & 37).
Would costs rise under The Portland Protocol? Are the extra costs offset by improved outcomes and decreased LOS? What did you find in your hospital?
A. As you know, the costs of insulin are minor compared to the indirect labor costs of nursing and pharmacy time. With the help of a medical student from Scotland (Stuart Robertson), we were able to meticulously analyze the incremental increase in all expenditures (direct and indirect) caused by using The Portland Protocol. The incremental cost of three days of The Portland Protocol (as compared to q 4 hour SQ control) is $138 per patient. Now, one has to factor in the cost savings from reduced LOS and reduced infection. When this is done, we can show that the hospital CONSERVATIVELY saves $680 per patient with The Portland Protocol, as compared to SQ insulin control, which is really ineffective control. Endocrine Practice, Volume 10, (supplement
2) March/April, pp. 21-33, 2004.
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V. Transitioning Patients from The Portland Protocol
What are the guidelines for patients during the transition period from IV insulin to SQ sliding scale? We transition our patients to the SQ the morning after surgery if they are on “the path”. Usually they are eating clear liquids. However, if you have a better suggestion about when to transition them, we would appreciate it. We are especially interested in how you manage the change to NPH when the patient is not eating their usual calories.
A. We transition the morning of the third postoperative day at 7 a.m. The reason we do this is because we found that the infection rates dropped to about 1 person with use into the first postoperative day but again dropped to an incredibly low 0.3 person (see figure 5 in paper) when the protocol was continued on the floor. The basis was statistical analysis that showed both first postoperative day and second postoperative day glucose to be significantly associated with infection. Third postoperative day was not associated. So we changed our original protocol (which was initially like yours – only in the ICU) to include the second postoperative day. It was at that point and at that point only, that we completely wiped out the risk of infection on DM patients. It is not as easy to accomplish the protocol on the floor and requires nursing, physician and administration buy-in. So it really depends on how good you want your results to be and what you are willing to do for that goal.
Transitions on the third postoperative day are easier – the patients stress hyperglycemia is nearly always resolved and insulin-dosing calculations are easier. Currently we just start back on their preoperative regimen, as BG levels beyond the 3rd postoperative day have not yet been shown to affect in-hospital outcomes. In a sense that is a “cop-out” on our part as good BG control is important in all patients. However, we have no data at this point to back up altering the patients’ outpatient glycemic control regimens when they come off the drip. Changing to SQ therapy on the first or second postoperative day is much harder as most patients still are experiencing post-operative stress hyperglycemia and many are not eating full enteral diets yet.
I could not give you an official recommendation of how to transition on the first or second postoperative day because I am strongly against it. Your physicians will not see the same quality of results we have published and may thus doubt the protocol and its rationale. If you switch on the third postoperative day, try going to basal / prandial insulin regimens. Switching on the third postoperative day is much simpler from the metabolic standpoint. I recommend extrapolating the 24-hour insulin requirement from the last 8 hours of the IV dose; take 40 percent of that calculated dose (not to exceed 48 units) and give it as Glargine insulin at 7 a.m.; take another 40 percent of that daily requirement and divide it up into 3 equal doses of preprandial Lispro or Aspart insulin.
I suggest you first transition using the IV protocol into the second postoperative day and try to get it used into the third postoperative day after that has been accomplished. It is definitely an educational process, but you will see infections disappear and mortality decrease.
Regarding transferring patients to the floor on a drip: Typically, we transfer our post-op patients the morning after surgery to the step-down unit, which will not take patients on insulin drips. Do your post-op patients stay in the ICU during this time? If not, how have the step-down units handled the protocol? Are there many articles that you would recommend regarding this issue? I am trying to start up a similar protocol for our patients and would appreciate any information.
A. We too transfer our patients to the floor the morning of the first postoperative day. We initially used the Continuous Intravenous Insulin (CII) in the ICU only, but as the benefits of first postoperative day and second postoperative day insulin drips became more and more obvious, we expanded our protocol to include floor patients. Originally the nurses did not want to take this on, but as they started to try it they found that is was not too demanding. We thus changed our nursing step-down policy to include insulin drips (along with NTG, Heparin, and Renal Dopamine – already there). If you do not include tight glucose control (CII drip) on the first and second postoperative days, you will not see the dramatic benefits we have published. Our statistical analysis shows both the first and second postoperative days to be important in terms of preventing infection. Lowering blood glucose only on the day of surgery decreased the DSWI rate to 1.0 percent whereas lowering blood glucose through the morning of the third postoperative day lowered the rate to 0.3 percent! For a reference see the Annals of thoracic surgery: Furnary, A.P.; Zerr, K.J.; Grunkemeier, G.L.; Starr, A.: “Continuous intravenous insulin infusion reduces incidence of deep sternal wound infection in diabetic patients after cardiac surgical procedures.” Ann Thorac Surg 1999; 67:352-62.
Is the insulin infusion automatically stopped on the third day even if the patient’s blood glucose is still bouncing above 200mg/dl or if they are unable to take PO?
A. If unable to take PO (as are many patients who remain in the ICU beyond the third postoperative day), we may continue the protocol and drip beyond the 3rd POD. If they are on the floor and not eating (because debilitated or on tube feeds), it is simply not convenient to continue the drip and we switch to SQ basal / prandial control. Note that by following the protocol closely virtually no patient’s glucose levels should be “bouncing around above 200” after the first 24 hours (let alone the third postoperative day).
We are interested in how the IV insulin protocol was implemented for diabetic cardiac fast-track patients. At what point is the patient considered stable to transfer to the step-down unit?
A. Patients typically transfer to our telemetry floor and not to the step-down beds on that floor. Originally I think they went to the step-down beds (which had a low RN/patient ratio), but the management of the drip was not found to be so labor intensive that it required a step-down bed. Therefore, now all patients go to a regular telemetry bed. They transfer to the floor based on routine cardiac stability criteria plus they must be on less than five units of insulin per hour.
Do you have suggestions regarding how to convert from an insulin drip to a subcutaneous insulin sliding scale?
A. By the time you are converting (third postoperative day) the patient should be going back to his/her outpatient hypoglycemic agents or his/her insulin regimen. If you switch on the third postoperative day, try going to basal / prandial insulin regimens. Switching on the third postoperative day is much simpler from the metabolic standpoint. I recommend extrapolating the 24 hour insulin requirement from the last 8 hours of the IV dose; take 40 percent of that calculated dose (not to exceed 48 units) and give it as Glargine insulin at 7 a.m.; take another 40 percent of that daily requirement and divide it up into 3 equal doses of preprandial Lispro or Aspart insulin.
If the patient is a new onset diabetic, an endocrine consult should be obtained.
When are the oral glycemic agents resumed?
A. On the third postoperative day.
If a patient is tolerating a full ADA diet on the second postoperative day, is it reasonable to start PO control at that time?
A. No, you will not achieve the tight control necessary to normalize the infection and mortality rates to that of the non-DM population. Non-enzymatic glycation still plays a role in the second postoperative day by impairing the healing process; free fatty acid down-regulation and enhanced oxidative glycolysis continue to reduce arrythmias and heart failure through the 2nd POD. By the third day there seems to be little correlation of mortality and infection to BG levels at this time.
Do you discontinue the infusion upon initiation of PO meds? Or does the infusion become “self weaning”; in other words, as the oral agents reduce blood sugar, the insulin infusion would naturally be titrated to off.
A. We stop the infusion at 7 a.m. and start the oral meds that same morning. Unless of course, the patient is not eating at all, then we continue the infusion.
On the third postoperative day, what time do you discontinue the insulin drip and when do you check the next bedside glucose?
A. We discontinue the drip right around breakfast (usually 7 a.m.). Then we return to the patient’s normal schedule of checks and pre-op meds control.
Was the insulin infusion ever turned off because the amount of insulin running into the patient was considered insignificant? For example, I tried one of my patient's blood glucoses against the Portland Protocol, and at one point the insulin rate would have theoretically been 0.0625 u/hour.
A. We have had patients on 0.3 u/hour. That seems to be our “low dose” limit. In order to be stopped, the blood glucose must remain below 110 mg/dl (5.5mmol/L) WITHOUT an insulin infusion.
Follow-up: If you did stop an “insignificant” amount, when and at what rate was the infusion restarted? For example, if you stopped at 0.0625 u/hour and the patient’s glucose was 6.5mmol/L, would you wait until they got to the interval above the target range and restart at 0.5 u/hour? Or would you restart at the initial infusion for when the patient first comes out of surgery?
A. If it were restarted, it would be restarted at 0.3 u/hour again once the blood glucose went above 125 mg/dl (6.9mmol).
Once a patient is discharged, I was wondering if you set a system in place to communicate with the patient’s primary care physician about the patient's hospital course in regards to their glucose values and diabetic control. It would seem that once the patient was out of the hospital, setting uncontrolled glucose values would/could impact a patient’s recovery.
A. No, we do not currently have such a system, although I think we should, because I think tight glucose control is just plain “good medicine”. However, pragmatically this is difficult in the current health-care system with sparse resources. Once patients come off the protocol in the hospital, their glucose levels are really all over the board. In our current scenario, they go back to their pre-hospital control, which if it was poor, remains poor. We have found that LOS, infection, and mortality are independently related to glucose levels only through the third postoperative day. Glucose values beyond the third day have no relationship to in-hospital outcomes as long as the patient is out of the ICU. The patient’s long-term recovery and incidence of recurrent events down the line may be significantly impacted if they remain hyperglycemic as outpatients. We are currently beginning the fourth phase of the Portland Diabetic Project, which will investigate the longer-term BG control question.
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VI. Checking Glucose Levels: Frequency and Methods
Must the insulin rate remain unchanged for four hours and able to go to every two hour BG-checks before going to the floor?
A. Blood glucoses are still checked on an every one-hour basis on the floor until there are four in a row that are within the target range (currently 80 – 120 mg/dl on the floor) with no change in the drip, as noted in the protocol. Most patients are on a stable drip rate by the middle of the first post-operative day.
Are fast-track patients handled the same way or do you transfer them while still on every one-hour checks?
A. As noted above, they can transfer while still on every one-hour checks.
What is the frequency of Chemsticks on the floor?
A. In the surgical ICU and on the telemetry floor we do glucose checks every hour if necessary, per protocol. On the floor, 70 percent of patients are checked every two hours. It is imperative to follow the frequency of testing as outlined in the protocol to keep The Portland Protocol both effective and safe. It is difficult to wake patients up at night to do a stick. But diabetic patients know they are at increased risk for infection and as such are willing to undergo this inconvenience as long as the benefits are explained to them.
How is blood glucose checked on the step-down unit: by finger stick method or arterial line sampling?
A. We use the finger stick method; the arterial lines come out in the unit, prior to transfer. Some patients have central lines still in that are capped; glucoses can be drawn from here as well.
Do you advocate maintaining the A-line to facilitate frequent blood sugar testing? I am concerned about potential patient discomfort and sleep deprivation with hourly finger sticks. What about non-invasive methods of measuring BG?
A. We recommend the A-line only in the ICU. We use finger sticks if there is no central IV line present. By the time patients have their lines out following surgery, their BG levels and insulin infusions should be at a stable rate and every 2 – 4 hourly BG checks are all that will be required per protocol at that point. We just do finger sticks at this point, but are investigating the feasibility of non-invasive monitors.
In patients who have not required insulin in the OR and whose initial BG in the ICU is less than 125 mg/dl now, how often do you continue to recheck the BG level during the patient’s ICU stay?
A. In that situation (rare in diabetics) we check in the ICU every two hours. If they do not require insulin drip according to the protocol in the ICU, then they go to the floor with every four-hour checks.
Regarding intra-operative control: When the patient is on the bypass machine, do you run the insulin drip in a peripheral IV or a central IV? Do you use an accucheck or similar glucometer to check glucose during surgery or do you do serum glucose levels?
A. On pump we use a central line for the drip. Our blood gas machine (one in each CVOR) gives us BG along with potassium and a full arterial blood gas.
There has been much discussion recently to the effect that existing glucose meters are not sufficiently accurate and precise for purposes of tight glycemic control protocols. Are handheld glucometers suitable for use for the protocol, or are benchtop units recommended?
A. Glucometers have varying levels of accuracy. We use the glucometer that has the highest correlation with lab values in the euglycemic range - from 70-110 mg/dl and even up to 150 mg/dl, as that is the "critical range" for maintaining safe control. We tested four different glucometers and found the SureStepPro® Professional Blood Glucose Management System by Johnson & Johnson to be the best at these ranges and with a variety of different blood samples - arterial, venous, and capillary. It was also the most accurate at varying temperature ranges, HCTs, and O2 levels. That is why we switched.
Inaccuracies at thehighlevels(>200mg/dL) are not as important as in the euglycemic ranges, since the actions required at the high levels are the same even when the meters are 10-20 points off. So accuracy does not matter in a pragmatic sense at those levels.
It does matter when we are in the low ranges, as that is where safety, in terms of preventing hypoglycemia, becomes paramount. LifeScan's SureStepPro® Professional Blood Glucose Management System, which is what we currently use, is highly accurate in the low ranges, which is exactly what we want.
We have recently implemented tight glycemic control at our institutions. We use the SureStepFlexx® Professional Blood Glucose Management System on nursing units. Because of increased finger sticks required by tight glycemic control, Point of Care® has been asked to investigate options such as alternate site testing, subcutaneous options, and smaller gauge lancets to reduce patient discomfort from numerous finger sticks. None of these are currently an option. What advice do you give institutions regarding the problem of increased finger sticks and resulting patient discomfort?
A. We take advantage of central venous lines and arterial lines when they are in place to do a venous or arterial line draw, producing a venous or arterial line blood sample that we use for glucose measurement. In addition to this, with the use of periprandial Humalog, by the time the patient is on the floor and the arterial and venous lines are out, the intravenous insulin infusion is maintained at a stable basal rate even around meals.
With this advance in our protocol (in 1999), patients on the floor only get needle sticks between every two to four hours. And if their glucoses are stable and their drips are stable going into the evening hours, then we let them coast through the night without a single finger stick.
As you can see on our protocol, the frequency of glucose testing decreases markedly once the basal rate is achieved. In this case, every one or two hour testing is not necessary and finger sticks are diminished. Furthermore, this is never a problem with the educated diabetic population, as many of them already know the risks associated with in-hospital hyperglycemia and are more than willing to undergo finger sticks. The problem only arises in the nondiabetic patient population with hyperglycemia, and these patients are very easy to get on to a basal rate.
The problem of increased finger sticks is a nursing issue rather than a patient problem in this regard. Nonetheless, new technologies are coming down the pike that I have been privileged to look at, that will give continuous glucose readings without any finger sticks whatsoever.
How are your tight glycemic control samples drawn? Venous? Finger stick? Line draw? Does it make a difference bother than in the normal pre-analytical considerations? We use arterial line drop samples as a first choice if an arterial line is in place, e.g., the ICU population. We secondarily use venous line drop samples (from a central line) if a CVP line is in place and an arterial line is not, e.g., ICU or step-down. In both cases, 10 cc of blood are withdrawn before the sample and is given back after the sample is taken, e.g., floor. Our final choice is capillary finger stick.
A. We chose a glucometer that gave us the most consistent results across all three samples – arterial, venous and capillary.
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VII. Miscellaneous Questions
Regarding concomitant IV fluid use with The Portland Protocol, particularly the IV fluids you use for hyperglycemic cardiac surgery patients: Are you using normal saline for these patients in the operating room and during the time their blood glucose is greater than 200 mg/dl?
A. In the OR we run Normasol-R (normal saline with Na-Acetate in it). Postoperatively we run ½ NSS. No Dextrose-containing solutions ever, anywhere… unless the patient is on TPN.
What solution did you mix the insulin in and at what concentration?
A. We put 125 units of insulin in 250 cc of normal saline solution. We find that 0.5 u/cc allows for fine titration of the drip.
What is your incidence of hypoglycemia perioperatively and postoperatively in your patients that have insulin drips? A recent study by Chaney et al shows that in trying to maintain normoglycemia they induced hypoglycemia in 40 percent of their patients.
A. Depends on the target range (see the slides). Our protocol has built-in anti-hypoglycemia measures. Because of these measures and because our acceptable range is not “normoglycemic”, we have seen chemical hypoglycemia in less than 0.5 percent of the patients on our 100 – 150 mg/dl protocol and in about 1.5 percent of our patients on the 70 – 110 protocol. Clinical hypoglycemia (symptomatic sweating, confusion, seizures, etc.) has occurred in less than .06 percent (3/5009). The difference between our protocol and the study you mention lies in the fact that we treat BG as the continuous variable it really is and finely titrate insulin doses against that continuous variable, rather than divide it up into 3 or four categorical variables, with little room for fine titration.
Does the protocol require a back-step infusion of D5W?
A. No, we found that the use of dextrose–containing solutions actually exacerbated stress hyperglycemia in our nondiabetic population and as they started eating and the dextrose IV was turned off they became hypoglycemic if the insulin was not turned off. So we eliminated the use of dextrose-containing IV solutions in the immediate postoperative period, which markedly reduced the BG levels in nondiabetics and reduced the requirement for insulin in this population.
Is the insulin infused via a dedicated line, or with other drips?
A. It is usually infused in a peripheral IV on the floor, but in the ICU we use it in conjunction with our other central line drips. We don’t mandate this. Some nurses prefer hooking it up in a peripheral line in the unit (40 percent), while others prefer the central route. When there is a problem controlling the glucose levels, I insist on central delivery as that provides the most consistent dosing.
Can you explain what is meant by the statement, “Implementation of the Portland CII protocol was staged to a specific point in time to achieve the highest compliance possible on the part of the nursing staff that administered the protocol”? What was the “staging”?
A. This simply means that we did not randomize the trial, but introduced the CII protocol in a staged fashion to our nursing units in order to teach our nurses how to properly follow the protocol.
Have you ever incorporated anything into either The Portland Protocol or the data collection of the study to see if insulin boluses were used in some patients?
A. Boluses are often used (see protocol) when the glucose is excessively high, when no BG response to an increase in insulin drip rate is seen, and in the operating room by the anesthesiologists who want rapid control.
How do you manage blood sugars intra-op on bypass?
A. We use intravenous insulin drip along with boluses as necessary to keep the blood glucose in the target range (currently between 70-110 mg/dl). I also advise measuring glucose every 15-30 minutes with ABGs (more frequent while on CPB).
Do you have any data on how the diabetic control of The Portland Protocol modifies outcomes other than wound infection after cardiac surgery?
A. In our references, you will see that we have published relationships with mortality, length of stay, and infection. There are others that are forthcoming.
What is the infection rate in diabetic, obese populations who have the IMA used as one of the perfusing vessels? Does this increase the risk? It would be interesting to subset this group.
A. We address this issue in some detail in the discussion section of our 1998 paper. As the glycemic control improved with the use of the Portland Protocol, the use of one (or two) IMAs gradually faded out as a multivariate factor in risk for infection. When we extended the drip into the OR and onto the floor, IMA virtually went away as a risk factor.
I am introducing your protocol for control of glycemia in cardiac surgery. Is it possible to increase the high end of normality to 175 mg/dl on the second postoperative day on the ward? And how do you control the blood glucose in the ward with the nurse?
A. It is possible, but your results may vary. If you increase the upper limits on the second postoperative day to175 mg/dl, you will not see the complete eradication of infectious risk that we have seen as nurses will tend to let patients drift above this level. Remember that although infection rates have an inflection point of 175 mg/dl, mortality decreases are seen even below 150 mg/dl. We used to allow this on the second postoperative day but found when we did not allow it to occur, the infection rate essentially went to 0 percent. The Protocol remains the same on the floor, with the singular exception that the glucose is diluted to one unit per 10 cc rather than the usual one unit per 2cc in the ICU.
Have you studied effects of the insulin infusion protocol on infection rates other than deep sternal?
A. Yes, we looked at deep sternal, superficial sternal, deep donor and superficial donor. The deep donor and deep sternal were the only rates affected. Later analysis showed that even deep donor site was not significantly affected, but this occurred concomitantly with the use of endoscopic harvesting of SVG in our institution. We have only had one deep leg site infection since using the endoscopic harvesting along with the DM protocol.
Several things are very clear to those of us working on this project: glucose testing must be more frequent immediately postop, insulin doses must be increased, physician and nursing tolerance for hyperglycemia must be decreased, and the use of vasopressors must be factored into the dosing of insulin.
A. Yes to all of the above.
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VIII. Reference Articles and Abstracts
Zerr, J; Furnary, A.P.; Grunkemeier, G.L.; Bookin, S.; Kanhere, V.; Starr, A.: “Strict glucose control lowers the risk of wound infection in diabetics following open heart surgery.” Ann Thorac Surg 1997; 63:356-61.
Furnary, A.P.; Zerr, K.J.; Grunkemeier, G.L.; Starr, A: “Continuous intravenous insulin infusion reduces incidence of deep sternal wound infection in diabetic patients after cardiac surgical procedures.” Ann Thorac Surg 1999; 67:352-62.
Furnary, A.P: “Insulin Infusions for Cardiac Surgery Patients with Diabetes: A Call to Reason.” Endocrine Practice 2002; Vol. 8, No.1
Furnary, A.P.; Gao, G.; Grunkemeier, G.L.; Wu, Y.X.; Zerr, K.J.; Bookin, S.O.; Floten, H.S.; Starr, A.: “Continuous insulin infusion reduces mortality in patients with diabetes undergoing coronary artery bypass grafting.” J Thorac Cardiovasc Surg. 2003; 125:1007-21.
Furnary AP; Wu Y; Bookin SO: “Effect of hyperglycemia and continuous intravenous insulin infusions on outcomes of cardiac surgical procedures: the Portland Diabetic Project. Endocrine Practice Mar-Apr; 10 Suppl 2:21-33, 2004.
Furnary, A.P.; Zerr, K.J.; Grunkemeier, GL; Heller, A.C.: “Hyperglycemia: A predictor of mortality following CABG in Diabetics.” Circulation 1999; Vol 100, #18; I-591.
Furnary, A.P.; Chaugle, H; Zerr, K.J.; Grunkemeier, GL: “Postoperative hyperglycemia prolongs length of stay in diabetic CABG patients.” Circulation 2000; Vol 102, #18; II-556.
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