AACE Patient Safety - Editorials

Safety in the ICU – Is Bedside Glucose Testing Safe For Our Patients?

In my recent editorial on the NICE-SUGAR study, I raised the question as to whether the methods commonly used to measure glucose levels at the bedside may be the source of error that may pose a hazard to the patient. A very important article by Scott, Bruns, Boyd, and Sacks, just published on-line in Clinical Chemistry1, reviews this important point and adds important new information to the excellent review by Dungan in 2007 in Diabetes Care2.
For several years, the clinical chemists and pathologists have been exploring the limitations of bedside glucose testing. Alterations in hematocrit and oxygen concentration may affect the result. Variations may be introduced by the site used to obtain the sample and whether the area is a site of low blood flow. In some cases, serious errors in insulin dosage have occurred when the bedside glucose method was not glucose specific and non-glucose sugars, such as icodextrin, used in peritoneal dialysis have caused the bedside readings to be falsely elevated, leading the clinicians into believing that more insulin was warranted, resulting in insulin overdosing and patient injury and deaths.
But Scott and his colleagues reviewed the evidence that suggests that the recent tight glucose control meta-analysis that failed to find the beneficial outcomes reported by Van den Berghe may have resulted from failure to ensure that the method of measuring glucose levels at the bedside were sufficiently accurate so as to prevent incorrect decisions, leading to iatrogenic hypoglycemia. Their analysis may be completely correct. They also comment on an earlier study by Boyd and Bruns who carried out simulation modeling studies to simulate the effects of the lack of precision of the glucose meters on the chosen dose of insulin for two insulin administration algorithms.
Their findings were sobering. A simulated total analytical error of only 5% led to an incorrect insulin dose in 8-23% of cases, but a total analytical error of 10% lead to incorrect insulin dosing in 16-45% of cases. To put this into context, the FDA allows 20% error for package insert claims of glucose meters. In other words, the acceptable standard for accuracy and precision of these medical devices is well below what is safe for our patients in critical care situations.
On the other hand, there is evidence that with proper training, the most accurate and precise glucose meters can be used safely in many settings in hospitals, and yield highly accurate results in a most timely fashion, and be useful in settings such as post-open heart surgery etc. But it appears that, until the FDA provides a higher standard of accuracy and precision and begins testing each type of instrument to verify the accuracy, it will be left to the providers of care to do a careful analytic review of the methods used in their institution, and to properly train their personnel and verify that the results they yield are sufficiently accurate to be used in the care of the vulnerable patient.
In summary, it appears that there is yet another part of the system of care that needs to be not taken for granted, if we are to achieve normoglycemia in our patients more often, and to avoid unnecessary hypoglycemia. We need to recheck whether our glucose testing is up to the task at hand. Scott et al have written an excellent reminder of the importance of looking carefully at the tools we use for glucose monitoring.
1. Scott MG, et al. Tight Glucose Control in the Intensive Care Unit: Are Glucose Meters up to the Task? Clinical Chemistry 55:1 18-20 (2009)
2. Dungan K, et al. Glucose Measurement: Confounding Issues in Setting Targets for Inpatient Management. Diabetes Care 30:403-409, 2007
Leave a Comment
MRR – Texas
March 31, 2009 – 16:29

Several interesting points came to mind when I reviewed the NICE-SUGAR study; the degree of severe hypoglycemia, the degree of cardiovascular mortality, the conventional group’s blood glucose levels are significantly lower than the vast majority of other outcome studies, and the number of severe septic patients in the intensive control branch of the study. According to the 2008 sepsis guidelines, the glycemic control target level for the septic patient is already in question and perhaps sepsis should be an exclusion criteria?

I was tasked with the development and oversight of a Tight Glycemic Control Program pilot study from May 2006 through April 2008 for a South Texas community hospital/level 2 trauma center. This included a 14 bed CCU, 12 bed M/S ICU and 12 bed trauma ICU as well as 4 M/S wards. Clinical inertia was our most difficult element to overcome and for the most part this was never accomplished. Clinical inertia was not only evident on physician’s part, but also administration, nursing, nutritional services, pharmacy, and the patients themselves. Accountability to noncompliance to protocols was lacking as well. The philosophy that inpatient glycemic control was not necessarily treating diabetes, yet acute hyperglycemia was never fully accepted. When results like ACCORD, ADVANCE, and VADT were released, I would usually take the phone off the hook and leave the hospital because those wbeepdo not support inpatient glycemic control would come out en mass wishing to compare apples to oranges. That is not necessarily the case with NICE-SUGAR. In our Trauma ICU, where support was highest, for the entire year of 2007, we had only 7% BG > 200mg/dL, less than 2% hypoglycemia under 50 mg/dL, and nearly 75% BG between 80 – 150 mg/dL.

Overall, I applaud the NICE-SUGAR research team for a job very well done and thank them for their contribution to this ongoing discussion. I do support further research to differentiate specific glycemic control target ranges for specific diagnosis, but I too fear this could cause a pendulum swing in the opposite direction resulting in less facilities participating in inpatient glycemic control resulting in less data for differentiation.

March 26, 2009 – 15:25
Subject: NICE -SUGAR

I think that the central goal of the ADA/AACE impatient glucose targets is safe with the protocols .
Hospitals should have protocols in place for using insulin to treat and prevent hyperglycemia.
Subcutaneous insulin may be used for both purposes in most noncritically ill patients, whereas intravenous infusion of
insulin is preferred in critically ill patients.
Be careful with this trial [NICE -SUGAR] to overcome clinical inertia.

Dr. Orlin Sergev – Charleston, SC
March 16, 2009 – 16:28

Dear Dr Hellman:
I enjoyed all the editorials on patients’ safety that you have recently published. I think that they raise questions which we as physicians are not always open about. Safety itself is frequently a topic that we love to discuss but it’s never our fault. In this connection, the article about overconfidence and medical errors is timely – especially, at this time of expected health care changes. Briefly, I do not think we as physicians are different from any other specialists in different areas. Lack of adequate knowledge in a special area is always a good reason to be noisy and seemingly overconfident. Most of us agree that the more you know the more you realize how much more you do not know. Overconfident behavior in front of outsiders seem to be the cover of ignorance. I think we have to improve medical education in order to make medical decisions safer. Just remember the pilot of the plane that landed in Hudson river – quiet professional on top of his performance. We in medical profession must lead in patients’ safety. In order to do that we have to lead the health care reform. We have to regain our authority, responsibility and accountability. (accountability without authority and responsibility is meaningless – see Dr Hellman’s article on Medicare). We have to lead the health education of the society – most of the tragic mistakes in life happen from ignorance. First and foremost, of course, we have to maintain the superiority in medical knowledge. We must improve the quality of medical education. Instead of multiple choice questions we have to put back in place the stern professor wbeepmade clinical judgements based on knowledge, experience, and gut feeling and set up a good personal example for the next generation of physicians. Pilot “Sully” did not read the manual and the guidelines how to handle the critical situation – all his life before, however, prepared him for the right on the spot decision. Decisions based on profound knowledge and experience are the safest! Let’s start the health care reform with ourselves.
Do not stop learning and teaching your team about sound and safe medical practices. When we have achieved that, we can confidently go out and regain our authority over various bureaucracies (government agencies-Medicare, insurances, medical malpractice law, etc).

james t poulos – west lafayette in
March 03, 2009 – 15:09

There was an article in acta scandinavia in january that showed very little hypoglycemia when intensive therapy is done right! I came across the article on medlinx in mid January, but it was actually published in October 2008. authors: Kaukonen KM et al in acta anaethesiol scandinavia and titled severe hypoglycemia in intensive insulin therapy.

Reply to james t poulos
Dr Hellman
March 04, 2009 – 16:12
Subject: Further thoughts related to the NICE-SUGAR study

Dear Dr. Poulos,

Thank you for calling attention to the study by Kaukonen KM et al. Your excellent point adds to the discussion generated by the NICE-SUGAR study. Their preliminary data analysis showed that error by provider was the most common cause of hypoglycemia. Their data implied, as I stated in my recent editorial, that improving the training and performance of those managing the insulin infusions greatly decreases the threat of hypoglycemia.

In this study by Kaukonen, done at the Helsinki University Central Hospital in Helsinki, Finland, the authors evaluated the incidence of hypoglycemia in all patients treated in two intensive care units between February 2005 and June 2006. They showed that severe hypoglycemia during intensive insulin therapy was rare in clinical practice. Analyzing data for 1124 patients and 61,203 glucose measurements, they found 36 measurements of severe (≤ 2.2mmol/L) hypoglycemia in 25 patients, with an incidence of 0.06% of severe hypoglycemia.

They commented that the frequency of blood glucose monitoring correlated inversely with the frequency and magnitude of severe hypoglycemia. In surgical patients, it is of note that five of the six instances of hypoglycemia occurred when a nurse failed to comply with the protocol.

The Helsinki group’s observations are entirely in keeping with the preliminary data from the NICE-SUGAR study and make a good deal of common sense. When the rate of decrease of glucose is rapid, for example greater than 1mg/dl/minute, simple arithmetic can tell us when the next glucose determination needs to occur to be able to safely avoid severe hypoglycemia. But if the frequency of checking of glycemic levels is arbitrary, and set too low, then hypoglycemia is to be expected much more often. The Kaukonen group avoided this by making sure the blood glucose sampling was relatively frequent.

In our clinical practice setting as well, the principles of safe handling of insulin infusions have been:

1.frequent monitoring, always at least hourly in ICU settings, more often when dealing with lower glycemic levels;
2.intensive training of nurses to make them expert in understanding how best to use algorithms;
3.specific points at which prolonged hyperglycemia or hypoglycemia necessitates immediate consultation with the responsible physician;
4.review of data to indicate variations in performance and appropriate correction and retraining when appropriate.

We too have extensive experience over many years with the safe use of insulin infusions in inpatient settings with relatively rare severe hypoglycemic episodes and little morbidity.

The NICE-SUGAR study should provide important information. We should not get too far ahead of their forthcoming data, but there is already abundant data, such as the important study from Helsinki, which show us that with a safer system of care, more ambitious glycemic control is both achievable and safe.

Kaukonen KM et al. Severe hypoglycemia during intensive insulin therapy, Acta Anaesthesiol Scand. 2009 Jan;53(1):61-65. Epub 2008 Oct 20.