Dynamic tight glycemic control during and after cardiac surgery is effective, feasible, and safe

Effect of glycemic control and glucose fluctuation on in-hospital adverse outcomes after on-pump coronary artery bypass grafting in patients with diabetes: a retrospective study

BACKGROUND

The optimal glycemic control level in diabetic patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (On-Pump) remains unclear. Therefore, this study aimed to investigate the effect of different blood glucose control levels and glucose fluctuations on in-hospital adverse outcomes in diabetic patients undergoing on-pump CABG.

METHOD

A total of 3918 patients with diabetes undergoing CABG were reviewed in this study. A total of 1638 patients were eligible for inclusion and were categorized into strict, moderate and liberal glucose control groups based on post-operative mean blood glucose control levels of  < 7.8 mmol/L, from 7.8 to 9.9 mmol/L and ≥ 10.0 mmoL/L, respectively. The primary endpoint was defined as a composite endpoint including in-hospital all-cause mortality and major cardiovascular complications. The secondary endpoint was defined as major cardiovascular complications including acute myocardial infarction, strokes and acute kidney injuries. To determine the associations between blood glucose fluctuations and adverse outcomes, patients with different glycemic control levels were further divided into subgroups according to whether the largest amplitude of glycemic excursion (LAGE) was ≥ 4.4 mmol/L or not.

RESULTS

A total of 126 (7.7%) patients had a composite endpoint. Compared with moderate control, strict glucose control was associated with an increased risk of the primary endpoint (adjusted OR = 2.22, 95% CI 1.18-4.15, p = 0.01) and the secondary endpoint (adjusted OR = 1.95, 95% CI 1.01-3.77, p = 0.049). Furthermore, LAGE ≥ 4.4 mmol/L was significantly associated with the primary endpoint (adjusted OR = 1.67, 95% CI 1.12-2.50, p = 0.01) and the secondary endpoint (adjusted OR = 1.75, 95% CI 1.17-2.62, p = 0.01),respectively. Patients with LAGE ≥ 4.4 mmol/L had significantly higher rates of the composite endpoint and major vascular complications in both the strict-control (the primary endpoint, 66.7% vs 12.4%, p = 0.034, the secondary endpoint, 66.7% vs 10.3%, p = 0.03) and moderate-control groups (the primary endpoint, 10.2% vs 6.0%, p = 0.03, the secondary endpoint, 10.2% vs 5.8%, p = 0.02).

CONCLUSIONS

After On-Pump CABG patients with diabetes, strict glucose control (< 7.8 mmol/L) and relatively large glucose fluctuations (LAGE ≥ 4.4 mmol/L) were independently associated with in-hospital adverse outcomes.

Performance of a 2-step insulin infusion protocol with adjustment of insulin doses for Asians in the medical intensive care unit following cardiothoracic surgery

Background

Most previous insulin infusion protocols are titrated for Westerners and are not simple to follow. In this study, we tested the efficacy and safety of our simple insulin infusion protocol utilizing lower insulin doses for Asians.

Methods

A total of 152 patients with type 2 diabetes undergoing cardiothoracic surgery were included. After surgery, blood glucose (BG) was initially managed according to our algorithm protocol, and subsequently by the post-algorithm protocol. Insulin infusion rates in the algorithm protocol were titrated in two steps according to (1) current BG levels and (2) the difference between current and previous BG levels. In the post-algorithm protocol, insulin lispro was injected subcutaneously in addition to intravenous insulin infusion according to BG levels. The efficacy was assessed as achievement rates of two target BG ranges (140-199 and 80-199 mg/dL), and safety was assessed as hypoglycemia (< 70 mg/dL) and protocol error rates.

Results

With the use of the algorithm protocol, 58.7% of 1749 BG measurements achieved a range of 140-199 mg/dL, and 95.9% achieved levels within the 80-199 mg/dL range. Hypoglycemia and protocol error rates were 0.47 and 0.51%, respectively. With the post-algorithm protocol, 48.7 and 98.3% of 898 BG measurements achieved each target range. Hypoglycemia and protocol error rates were 0.78 and 0.22%, respectively. Severe hypoglycemia (< 40 mg/dL) was not observed.

Conclusions

Our insulin infusion protocol seems to be efficacious, safe, and widely feasible for Asian patients because of its simplicity and lower insulin dose.

Feasibility and precision of subcutaneous continuous glucose monitoring in patients undergoing CABG surgery

OBJECTIVES

To evaluate if subcutaneous continuous glucose monitoring (sCGM) is feasible in cardiac surgery and if reliable glucose values are reported under hypothermic extracorporeal circulation.

DESIGN

Feasibility trial.

SETTING

University hospital.

PARTICIPANTS

Ten consecutive patients undergoing coronary artery bypass grafting.

INTERVENTIONS

Prior to surgery, during hypothermic extracorporeal bypass, and 48 hours postoperatively, arterial blood glucose samples were compared with sCGM every 30 minutes. Statistical analysis utilized Clarke's error grid and Bland-Altman plot.

MEASUREMENTS AND MAIN RESULTS

Three hundred fifty-one pairs of glucose measurements were recorded including 59 during hypothermic extracorporeal circulation. Agreement between these measurements was acceptable, with a regression line slope of 0.88 and an offset of 17.4 (p = 0.87). Error grid analysis indicated a safe margin of 99.1% within zone A (no clinical action needed) or zone B (values would not lead to inappropriate treatment). Only 0.9% were plotted in zone D (potentially dangerous failure). Measurements during hypothermic extracorporeal circulation were comparable. Correlation coefficient was 0.760. The offset regression line was more pronounced (50.9) with a flatter slope (0.640). Within the error grid all plot values were in zone A or B.

CONCLUSIONS

sCGM compared with arterial blood gas glucose monitoring under hypothermic extracorporeal circulation appears to be feasible and reliable.

Monitoring states of altered carbohydrate metabolism via breath analysis: are times ripe for transition from potential to reality?

PURPOSE OF REVIEW

To introduce the potential of breath analysis as a diagnostic or monitoring tool in diabetes.

RECENT FINDINGS

Blood testing for plasma glucose and other metabolic variables is the base for the diagnosis and management of diabetes, whose two main types (type 1 and type 2, T1DM, T2DM) are projected to affect 450 million by 2030. As blood testing is often uncomfortable, painful, costly, and in some situations unreliable, the quest for alternative, noninvasive methods has been ongoing for decades. Breath analysis has emerged as an ideal alternative as sample collection is easy, painless, flexible, noninvasive, practical, and inexpensive. No single exhaled gas can reflect systemic glucose concentrations. Multiple gases, however, have been linked to various aspects of glucose metabolism, and integrated analysis of their simultaneous profiles during prolonged glycemic fluctuations has yielded accurate predictions of plasma values, building expectation that a clinically usable breath-based glucometer may be developed within a few years.

SUMMARY

While prototypes of hand-held breath testing glucometers may still be several years away, current research shows the imminent promise of this methodology and the widening support for its development.

Intensive glycemic control after heart transplantation is safe and effective for diabetic and non-diabetic patients

Some studies have shown increased mortality, infection, and rejection rates among diabetic (DM) compared to non-diabetic (non-DM) patients undergoing heart transplant (HT). This is a retrospective chart review of adult patients (DM, n = 26; non-DM, n = 66) undergoing HT between June 1, 2005, and July 31, 2009. Glycemic control used intravenous (IV) and subcutaneous (SQ) insulin protocols with a glucose target of 80-110 mg/dL. There were no significant differences between DM and non-DM patients in mean glucose levels on the IV and SQ insulin protocols. Severe hypoglycemia (glucose <40 mg/dL) did not occur on the IV protocol and was experienced by only 3 non-DM patients on the SQ protocol. Moderate hypoglycemia (glucose >40 and <60 mg/dL) occurred in 17 (19%) patients on the IV protocol and 24 (27%) on the SQ protocol. There were no significant differences between DM and non-DM patients within 30 d of surgery in all-cause mortality, treated HT rejection episodes, reoperation, prolonged ventilation, 30-d readmissions, ICU readmission, number of ICU hours, hospitalization days after HT, or infections. This study demonstrates that DM and non-DM patients can achieve excellent glycemic control post-HT with IV and SQ insulin protocols with similar surgical outcomes and low hypoglycemia rates.

Protocol-directed insulin infusion sliding scales improve perioperative hyperglycaemia in critical care

Perioperative hyperglycaemia is associated with poor outcomes in patients undergoing cardiac surgery. Frequent postoperative hyperglycaemia in cardiac surgery patients has led to the initiation of an insulin infusion sliding scale for quality improvement.

A systematic review was conducted to determine whether a protocol-directed insulin infusion sliding scale is as safe and effective as a conventional practitioner-directed insulin infusion sliding scale, within target blood glucose ranges.

A literature survey was conducted to identify reports on the effectiveness and safety of an insulin infusion protocol, using seven electronic databases from 2000 to 2012: MEDLINE, CINAHL, EMBASE, the Cochrane Library, the Joanna Briggs Institute Library and SIGLE. Data were extracted using pre-determined systematic review and meta-analysis criteria.

Seven research studies met the inclusion criteria. There was an improvement in overall glycaemic control in five of these studies. The implementation of protocols led to the achievement of blood glucose concentration targets more rapidly and the maintenance of a specified target blood glucose range for a longer time, without any increased frequency of hyperglycaemia. Of the seven studies, four used controls and three had no controls.

In terms of the meta-analysis carried out, four studies revealed a failure of patients reaching target blood glucose levels (P < 0.0005) in the control group compared with patients in the protocol group. The risk of hypoglycaemia was significantly reduced (P <0.00001) between studies.

It can be concluded that the protocol-directed insulin infusion sliding scale is safe and improves blood glucose control when compared with the conventional practitioner-directed insulin infusion sliding scale. This study supports the adoption of a protocol-directed insulin infusion sliding scale as a standard of care for post-cardiac surgery patients.

The clinical potential of exhaled breath analysis for diabetes mellitus

Various compounds in present human breath have long been loosely associated with pathological states (including acetone smell in uncontrolled diabetes). Only recently, however, the precise measurement of exhaled volatile organic compounds (VOCs) and aerosolized particles was made possible at extremely low concentrations by advances in several analytical methodologies, described in detail in the international literature and each suitable for specific subsets of exhaled compounds. Exhaled gases may be generated endogenously (in the pulmonary tract, blood, or peripheral tissues), as metabolic by-products of human cells or colonizing micro-organisms, or may be inhaled as atmospheric pollutants; growing evidence indicates that several of these molecules have distinct cell-to-cell signaling functions. Independent of origin and physiological role, exhaled VOCs are attractive candidates as biomarkers of cellular activity/metabolism, and could be incorporated in future non-invasive clinical testing devices. Indeed, several recent studies reported altered exhaled gas profiles in dysmetabolic conditions and relatively accurate predictions of glucose concentrations, at least in controlled experimental conditions, for healthy and diabetic subjects over a broad range of glycemic values. Optimization of this methodology and validation in large-scale trials under a wider range of conditions is needed to determine its true potential to transition into practical clinical use.

Compliance with surgical care improvement project blood glucose--a marker for euglycemia, but does it put our patients at risk?

To improve outcomes in open heart surgery (OHS) patients, the Surgical Care Improvement Project (SCIP) requires 6 am postoperative day (POD) 1 and 2 blood glucose (BG) to be ≤200mg/dL. This study examined risk factors for SCIP noncompliance when using an insulin infusion protocol (IIP) and evaluated this SCIP metric as a surrogate for glycemic control. The authors divided 99 consecutive OHS patients, all subjected to 1 uniform IIP, into 2 groups: Group 1-SCIP compliant (n=79) and Group 2-SCIP noncompliant (n=20). They determined mean BG for the first 48 postoperative hours, percent of total time with hyperglycemia (% time BG >200mg/dL) for each group, and assessed risk of SCIP noncompliance as relates to multiple risk factors including intensity of IIP application, and switching to subcutaneous (SQ) insulin prior to 6 am on POD 2. Group 1 had lower mean BG than Group 2 and percent of total time with hyperglycemia, P<0.0001. Multivariate analysis showed diabetes, obesity in nondiabetics, and switching to SQ insulin prior to 6 am on POD 2 to be risk factors for SCIP noncompliance. The 6 am BG values on POD 1 or POD 2 each correlated with average postoperative BG, and compliance with the SCIP BG metric was associated with virtually uniform BG ≤200mg/dL. IIP application was not significantly different between groups (P=0.2). Only patients who had been switched to SQ insulin prior to 6 am POD 2 were noncompliant at 6 am on POD 2. There were hypoglycemic events (BG <70mg/dL) in 15 of 99 patients (15%), 12 of whom (80%) were in Group 1. Noncompliance with this SCIP measure occurred more frequently in patients with diabetes or, if nondiabetic, in those patients with obesity. A trend toward increased insulin assessments in the SCIP noncompliant group suggests that 1 uniform IIP for all patients may not be effective. By not requiring the reporting of hypoglycemia, SCIP may inadvertently be exposing patients to harm.

Insulin pump therapy in patients with diabetes undergoing surgery

OBJECTIVE

To assess perioperative management of patients with diabetes mellitus who were being treated with insulin pump therapy.

METHODS

We reviewed records for documentation of insulin pump status and glucose monitoring during preoperative, intraoperative, and postanesthesia care unit (PACU) phases of surgery.

RESULTS

Thirty-five patients (21 men) with insulin pumps underwent surgical procedures between January 1, 2006, and December 31, 2010. Mean age was 56 years, mean diabetes duration was 31 years, and mean duration of insulin pump therapy was 7 years. All patients were white, and 29 had type 1 diabetes mellitus. Of the 50 surgical procedures performed during the study period, 16 were orthopedic, 9 were general surgical, 7 were urologic, and 7 were kidney transplant operations; the remaining 11 procedures were in other surgical specialties. The mean (± standard deviation) time in the preoperative area was 118 ± 75 minutes, mean intraoperative time was 177 ± 102 minutes, and mean PACU time was 170 ± 78 minutes. Of the 50 procedures, status of pump use was documented in 32 cases in the preoperative area, 14 cases intraoperatively, and 30 cases in the PACU. Glucose values were recorded in 47 cases preoperatively, 30 cases intraoperatively, and 48 cases in the PACU.

CONCLUSIONS

Results showed inconsistent documentation of pump use and glucose monitoring throughout the perioperative period, even for patients with prolonged anesthesia and recovery times. It was often unclear whether the pump was in place and operational during the intraoperative period. Guidelines should be developed for management of insulin pump-treated patients who are to undergo surgery.

The correlation between peri-operative hyperglycemia and mortality in cardiac surgery patients: a systematic review

BACKGROUND

Hyperglycemia occurs frequently in patients undergoing cardiac surgery. It has been identified as a risk factor for increased peri-operative morbidity and mortality.

AIM

To review the evidence of the correlation of peri-operative hyperglycemia with mortality in cardiac surgery patients and to discuss the main results in order to provide evidence-based knowledge for the appropriate glycemic control.

METHODS

We searched the electronic databases MEDLINE, CINAHL and EMBASE in June 2010. The material of our study was articles published between 1 January 1990 and 31 May 2010, which investigated the correlation between peri-operative hyperglycemia and in-hospital and/or 30-day cardiac surgery mortality.

RESULTS

Out of the 16 reviewed articles in our study, 12 (75%) significantly associated hyperglycemia and inadequate blood glucose control with increased mortality. In addition, four of the reviewed articles were controlled randomized trials and among them only one demonstrated strong correlation between poor glycemic control and mortality. No study was multi-centre and the reviewed articles were characterized by different definitions of peri-operative hyperglycemia, different intensity and duration of the applied therapy and heterogeneity of the population.

CONCLUSION

It is clear that peri-operative hyperglycemia is harmful for cardiac surgery patients. The significant shortage of randomized controlled trials, the absence of multicentre studies, the different definitions of peri-operative hyperglycemia, the different intensity and duration of the applied insulin therapy protocol and the heterogeneity of the studied population (diabetics and non-diabetics) are significant limitations, which could explain the inconsistent findings of the literature. These limitations indicate the need for further research.

Glycemic control: how tight in the intensive care unit?

Determining the optimal level of glycemic control in critical illness has proven difficult since the original Leuven study conclusions were published in 2001. Conflicting evidence, scientific methodologies, hospital cultures, and a-priori biases have challenged many clinical practice patterns. Specifically, the prioritization of patient safety has resulted in many practitioners changing from a glycemic control target of 80-110 mg/dL to a more liberal target of 140-180 mg/dL. However, a detailed examination of the evidence can provide a more population-specific glycemic control strategy. This position paper presents an approach for cardiac surgery patients in the intensive care unit (ICU) consistent with extant evidence and real-life variables. We argue that in the cardiac surgery ICU, glycemic targets may be as low as 80-110 mg/dL when formal intensive insulin therapy and nutrition support protocols are used with low rates of hypoglycemia, patient safety mechanisms, properly trained staff, and a supportive hospital administration all in force. Cardiac surgery ICUs that already follow this model may continue with 80-110 mg/dL blood glucose targets, whereas others may advance their blood glucose targets in a stepwise fashion: from 140 to 180 mg/dL to 110-140 mg/dL to 80-110 mg/dL, on the basis of their performance.

Perioperative glycemic control: use of a hospital-wide protocol to safely improve hyperglycemia

Perioperative hyperglycemia impairs immunity and contributes to increased susceptibility to infection, higher incidence of multiorgan dysfunction, and greater mortality. Strict glycemic control is associated with lower infection rates, decreased length of stay (LOS), and faster recovery. A protocol that standardized preoperative education, testing, and treatment of elevated blood glucose (BG) safely improved perioperative glycemic control. Preoperative average BG improved from 191 to 155 mg/dL (P=.016); postoperative average BG decreased from 189 to 168 mg/dL (P=.094). The percentage of patients presenting with BG greater than 180 mg/dL preoperatively and achieving BG less than 180 mg/DL postoperatively increased from 21% to 43% (P = .09). Even though some results were statistically non-significant, the data showed a trend toward improvement with the new protocol. Good perioperative glycemic control, without an increased risk of hypoglycemia, is achievable.

Carbohydrate provision in the era of tight glucose control

Glycemic control in the critically ill patient has remained a controversial issue over the last decade. Several large trials, with widely varying results, have generated significant interest in defining the optimal target for blood-glucose control necessary for improving care while minimizing morbidity. Nutritional support has evolved into an additional area of critical care where appropriate practices have been associated with improved patient outcomes. Carbohydrate provision can impact blood-glucose levels, and the relationship between nutrition and glucose levels has become more complex in the era of improved glycemic control. This review discusses the controversy surrounding intensive-insulin therapy in the intensive care unit and explores the relationship with nutritional support, both in the enteral and parenteral form. Achieving realistic goals in both carbohydrate provision and glycemic control may improve patient outcome, and are not mutually exclusive practices.

Intensive management of hyperglycaemia in acute coronary syndromes. Study design and rationale of the BIOMArCS 2 glucose trial

BACKGROUND

Elevated admission plasma glucose is associated with increased mortality in patients who are admitted with an acute coronary syndrome. This may be mediated by increased inflammation, apoptosis and coagulation, and by a disturbed endothelial function that can be found in hyperglycaemic patients. Insulin has several characteristics that may potentially counteract these mechanisms.

METHODS

The BIOMArCS programme is a multi-centre initiative and currently consists of three different studies. The effects of acute coronary syndrome on acute biomarkers washout are studied in the BIOMArCS pilot and the value of biomarkers in predicting upcoming acute coronary syndrome events is studied in BIOMArCS 1. The third study (BIOMArCS 2 glucose), which will be presented here, investigates the effectiveness and safety of intensive glucose level control compared with conventional glucose management in patients with acute coronary syndrome and an admission plasma glucose of 7.8-16 mmol/l. In BIOMArCS 2 glucose, a total of 300 patients without insulin-treated diabetes mellitus will be randomized in a 1:1 ratio to either intensive or conventional glucose management on top of standard medical care. The primary endpoint is infarct size as expressed by the cardiac troponin T level 72 h after admission. To study the metabolic effects of insulin administration, we will investigate biomarker washout patterns of various metabolic mechanisms up to 7 days after admission. These markers will address inflammation, oxidative stress, hypercoagulability, endothelial activation and vasodilatation.

IMPLICATIONS

Current acute coronary syndrome guidelines lack a clear strategy for hyperglycaemia treatment. This study will extend our knowledge on this matter as it may clarify mechanisms and generate hypotheses of if and how myocardial infarct size may be limited by glucose management at admission.

Do nondiabetic patients undergoing coronary artery bypass grafting surgery require intraoperative management of hyperglycemia?

OBJECTIVE

To study the effect of blood glucose (BG) control with insulin in preventing hyperglycemia during and after coronary artery bypass grafting (CABG) surgery in nondiabetic patients.

METHODS

In a randomized clinical trial, 120 nondiabetic patients who underwent elective CABG surgery were enrolled for study of whether the control of hyperglycemia was a need in such a surgery in a teaching heart hospital. The patients were randomly divided into study (n=60) and control (n=60) groups. In the study group, insulin was infused to maintain BG level between 110 mg/dL and 126 mg/dL (a modified insulin therapy protocol, and in the control group, the patients were excepted). Insulin therapy was limited to intraoperative period. BG levels during surgery and up to 48 hours after surgery and early postoperative complications were compared between the study and control groups.

RESULTS

One hundred seventeen patients completed the study (59 patients in study group and 58 in control group). Peak intraoperative BG level in the study group was 126.4±17.9 mg/dL and in the control group was 137.3±17.6 mg/dL (p=0.024). The frequencies of severe hyperglycemia (BG≥180 mg/dL) were 6 of 59 (10.1%) in the study group and 19 of 58 (32.7%) in the control group during operation (p=0.002). Peak postoperative BG level in the study group was 194.8±41.2 mg/dL and was 199.8±43.2 mg/dL in the control group (p=0.571). There was no hypoglycemic event in either group. The frequencies of early postoperative complications were 10 of 59 (16.9%) in the study group and 19 of 58 (32.7%) in the control group (p=0.047).

CONCLUSIONS

Hyperglycemia (BG≥126 mg/dL) is common in nondiabetic patients undergoing CABG surgery. A modified insulin therapy to maintain BG level between 110 mg/dL and 126 mg/dL may be acceptable for avoiding hypoglycemia and keeping intraoperative BG levels in acceptable range in nondiabetics.

Management of tight intraoperative glycemic control during off-pump coronary artery bypass surgery in diabetic and nondiabetic patients

OBJECTIVES

To optimize intra- and postoperative insulin management in cardiac surgical patients.

DESIGN

A prospective, randomized, open-label, single-center study.

SETTING

A large nonuniversity hospital.

PARTICIPANTS

Sixty diabetics and 60 nondiabetics undergoing off-pump cardiac bypass surgery.

INTERVENTIONS

Intra- and postoperative tight glycemic control were achieved using different approaches with a modified insulin protocol.

MEASUREMENTS AND MAIN RESULTS

Nondiabetics were divided randomly: in the ND-ind group (n = 30), insulin was started at induction according to preinduction blood glucose (BG) concentrations. In group ND >110 (n = 30), insulin was started when BG concentrations exceeded 110 mg/dL during surgery. Up to 85% of the ND >110 group started on insulin intraoperatively. Intraoperatively, the ND-ind group had more BG within target (80-110 mg/dL) (p = 0.002), less BG >130 mg/dL (p = 0.015), and more BG between 70 and 79 mg/dL (p = 0.002). In diabetics, BG concentration was checked every 30 (DM-30), n = 30) versus 60 minutes (DM-60, n = 30) to improve the protocol's performance. Intraoperatively, there were more BG concentrations within target (80-110 mg/dL) (p = 0.02) and less >130 mg/dL (p = 0.0002) in the DM-30 group. During surgery, the hyperglycemic index and the glycemic penalty index were lower in the ND-ind group (p < 0.05). Postoperatively, the mean BG concentrations, hyperglycemic index, and glycemic penalty index in diabetics and nondiabetics were comparable between groups (p < 0.05). In the overall 2,641 BG samples, the lowest BG concentration in the operating room was 71 and in the intensive care unit (ICU) it was 61 mg/dL.

CONCLUSIONS

In diabetics and nondiabetics undergoing off-pump coronary artery bypass surgery, tight perioperative glycemic control is feasible and efficient, with minimal risks for hypo- and hyperglycemia. In nondiabetics, starting insulin therapy from induction onwards results in more measurements within target, without affecting the mean BG. In diabetics, decreasing the sampling interval from 60 to 30 minutes results in more measurements within target and in a mean blood glucose within target at ICU arrival.

Intensive insulin therapy during cardiovascular surgery

Recent evidence in the fields of surgery, emergency and critical care medicine indicates that strict glycemic control results in lower mortality. Hyperglycemia occurs frequently in patients with and without diabetes during cardiovascular surgery, especially during cardiopulmonary bypass. However, strict glucose control is difficult to achieve during cardiovascular procedures. To establish effective intensive insulin therapy during cardiovascular surgery, we conduct continuous blood glucose monitoring and employ automatic control by using an artificial endocrine pancreas (the STG-22, Nikkiso, Tokyo, Japan). In this review, we will outline the present status and problems of conventional glycemic control for perioperative cardiovascular surgery and introduce the new perioperative blood glucose management method that we are testing now. We will also discuss the importance of perioperative glycemic control for cardiovascular surgery as well as future prospects.

Superiority of moderate control of hyperglycemia to tight control in patients undergoing coronary artery bypass grafting

OBJECTIVE

Although consensus in cardiac surgery supports tight control of perioperative hyperglycemia (glucose<120 mg/dL), recent studies in critical care suggest moderate glycemic control may be superior. We sought to determine whether tight control or moderate glycemic control is optimal after coronary artery bypass grafting.

METHODS

From 1995 to 2008, a total of 4658 patients with known diabetes or perioperative hyperglycemia (preoperative glycosylated hemoglobin≥8 or postoperative serum glucose>126 mg/dL) underwent isolated coronary artery bypass grafting at our institution. Patients were stratified into 3 postoperative glycemic groups: tight (≤126 mg/dL), moderate (127-179 mg/dL), and liberal (≥180 mg/dL). Preoperative risk factors, glycemic management, and postoperative outcomes were analyzed.

RESULTS

Operative mortality was 2.5% (119/4658); major complication rate was 12.5% (581/4658). Relative to moderate group, more patients in tight group had preoperative renal failure (tight 16.4%, 22/134, moderate 8.3%, 232/2785, P=.001) and underwent emergent operations (tight 5.2%, 7/134, moderate 1.9%, 52/2785, P=.007); however, Society of Thoracic Surgeons predicted mortality risk was lower in tight group (P<.001). Moderate group had lowest mortality (tight 2.9%, 4/134, moderate 2.0%, 56/2785, liberal 3.4%, 59/1739, P=.02) and incidence of major complications (tight 19.4%, 26/134, moderate 11.1%, 308/2785, liberate 14.2%, 247/1739, P<.001). Risk-adjusted major complication incidence (adjusted odds ratio 0.7, 95% confidence interval 0.58-0.87) and mortality (adjusted odds ratio 0.6, 95% confidence interval 0.37-0.83) were lower with moderate glucose control than with tight or liberal management.

CONCLUSIONS

Moderate glycemic control was superior to tight glycemic control, with decreased mortality and major complications, and may be ideal for patients undergoing isolated coronary artery bypass grafting.

Glucose and insulin administration while maintaining normoglycemia during cardiac surgery using a computer-assisted algorithm

BACKGROUND

applying the principles of the hyperinsulinemic-normoglycemic clamp technique we have introduced glucose and insulin administration while maintaining normoglycemia (GIN therapy) to surgical patients. The objective of this study was to evaluate a novel computer software (GIN Computer Software [GINCS]) program using an algorithm based on the original clamp equation and modified for its use during cardiac surgery.

METHODS

thirty-six patients without diabetes undergoing elective cardiac surgery were randomly assigned to manually controlled or computer-guided GIN therapy. In both groups insulin was administered at 5 mU/kg/min during surgery. Simultaneously, 20% dextrose was infused at a rate adjusted to maintain blood glucose (BG) between 4.0 and 6.0 mmol/L. The adjustments were made either following an algorithm based on our previous GIN experience or suggestions made by the software program. The primary outcome was the achievement of target glycemia.

RESULTS

normoglycemia was achieved in both groups as reflected by mean BG concentrations of 5.0 ± 0.5 mmol/L and 5.1 ± 0.2 mmol/L. Mean sampling intervals were longer in the GINCS group than in the manual group (21.5  ± 1.9 vs. 14.2 ± 2.2 min, P < 0.001). The GINCS therapy was associated with a greater percentage of BG measurements within target (manual group, before cardiopulmonary bypass [CPB] 79.7%, during CPB 68.1%, and after CPB 69.1%; GINCS group, before CPB 94.1%, during CPB 92.4%, and after CPB 97.7%; P < 0.001). No hypoglycemia was observed.

CONCLUSIONS

the use of a computer-guided GIN protocol in patients without diabetes undergoing open heart surgery provided excellent and safe glycemic control.

Perioperative glucose and insulin administration while maintaining normoglycemia (GIN therapy) in patients undergoing major liver resection

BACKGROUND

Although hyperglycemia is a well-recognized risk factor in the context of cardiac surgery, the relevance of perioperative glycemic control for patients undergoing major noncardiac operations has received little attention. We designed this study to assess the hyperglycemic response to liver resection, and to test the hypothesis that perioperative glucose and insulin administration while maintaining normoglycemia (GIN therapy) provides glycemic control superior to that achieved by the conventional use of insulin.

METHODS

Patients were randomly assigned to GIN therapy or standard therapy (control group). In the GIN therapy group, insulin was administered at 2 mU . kg(-1) . min(-1) during surgery. At the end of surgery, the insulin infusion was decreased to 1 mU . kg(-1) . min(-1) and continued for 24 hours. Dextrose 20% was infused at a rate adjusted to maintain blood glucose within the target range of 3.5 to 6.1 mmol . L(-1) (63-110 mg . dL(-1)). Patients in the standard therapy group received a conventional insulin sliding scale during and after surgery. The mean and SD of blood glucose as well as the percentage of blood glucose values within the target range were calculated. To evaluate intrasubject variability, the coefficient of variability (CV) of blood glucose was calculated for each patient. Episodes of severe hypoglycemia, i.e., blood glucose <2.2 mmol . L(-1) (40 mg . dL(-1)), were recorded. The primary outcome was the proportion of normoglycemic measurements.

RESULTS

We studied 52 patients. The mean blood glucose value in patients receiving GIN therapy always remained within the target range. The blood glucose levels were lower in the GIN therapy group than in the standard therapy group (during surgery, P < 0.01; after surgery, P < 0.001). In nondiabetic patients receiving GIN therapy (n = 19), target glycemia was achieved in 90.1% of the blood glucose measurements during surgery and in 77.8% of the measurements after surgery. In diabetic patients receiving GIN therapy (n = 7), target glycemia was achieved in 81.2% of the blood glucose measurements during surgery and in 70.5% of the measurements after surgery. In nondiabetic patients receiving standard therapy (n = 19), target glycemia was achieved in 37.4% of the blood glucose measurements during surgery and in 18.3% of the measurements after surgery. In diabetic patients receiving standard therapy (n = 7), target glycemia was achieved in 4.3% of the blood glucose measurements during surgery and in 2.9% of the measurements after surgery. The SD and CV of blood glucose were smaller in the GIN therapy group than in the standard therapy group, especially in nondiabetic patients after surgery (SD, P < 0.001; CV, P = 0.027). No patients receiving GIN therapy experienced severe hypoglycemia during surgery. One patient receiving GIN therapy experienced hypoglycemia in the intensive care unit after surgery without neurological sequelae.

CONCLUSIONS

GIN therapy effectively provides normoglycemia in patients undergoing liver resection (clinicaltrials.gov, NCT00774098).

Tight glycaemic control: clinical implementation of protocols

Implementation of tight glycaemic control in hospitalised patients presents a huge challenge. It concerns many patients, there are many interfering factors and many health-care professionals are involved. The current literature provides little practical guidance. This article offers the clinical anesthesiologist direction for the organisation of inpatient blood glucose control in acute situations, in the perioperative setting and in the intensive care unit. An effective, safe and user-friendly algorithm for intravenous insulin administration is presented that can be executed by regular nurses and used in many situations. Practical advice is offered for the use of subcutaneous basal-bolus insulin, for fasting orders and for transition to discharge care. The main safety considerations are discussed.

Is hypoglycaemia dangerous?

Tight glycaemic control (TGC) for patients treated in an intensive care unit ICU is associated with an increased risk for hypoglycaemia. Since hypoglycaemia mainly occurs in the sickest patients, no matter whether TGC is applied or not, it might be a marker for severity of illness or a harmful event in itself. Furthermore, it remains a matter of debate whether harmful effects of hypoglycaemia outbalance the clinical benefits of TGC. This review focusses on the clinical manifestations of hypoglycaemia in the critically ill and highlights its potential short- and long-term consequences specifically concerning neurocognitive function.

How to implement a clinical pathway for intensive glucose regulation in acute coronary syndromes

Hyperglycemia upon admission of myocardial infarction patients predicts inferior clinical outcomes. Current strategies investigating hyperglycemia correction mostly use glucose-driven protocols. Implementation of these often labor-intensive protocols might be facilitated with the approach of a clinical pathway. Therefore, we evaluated the implementation of our glucose-driven protocol.We adapted a protocol for use in our coronary care unit (CCU), which was implemented according to the steps of a clinical pathway. To compensate for carbohydrates in meals we additionally developed a regimen of subcutaneous insulin.Protocol adherence was facilitated with a Web-based insulin calculator. All hyperglycemic patients admitted to the CCU were eligible for treatment according to this protocol.In a 4-month period, 643 glucose measurements were obtained in hyperglycemic patients admitted to our CCU. Patients were treated intensively with IV insulin for 35 hours and had 23 glucose measurements in this time span on average. This regimen achieved a median glucose of 6.2 mmol/L. Severe hypoglycemia occurred in only 1.1% of measurements and was without severe clinical side effects.Introduction of new intensive insulin protocol according to the steps of a clinical pathway is safe and feasible. The presence of a clinical pathway coordinator and sound communication are important conditions for successful introduction, which can be further aided with a computerized calculator.

Clinical review: Intensive insulin therapy in critically ill patients: NICE-SUGAR or Leuven blood glucose target?

CONTEXT

Hyper- and hypoglycemia are associated with increased mortality of critically ill patients, but whether this association is causal remains unclear. Early randomized-controlled studies compared insulin infusion targeting "age-normal" blood glucose levels, labeled intensive insulin therapy, with an approach that considered hyperglycemia as a beneficial adaptation. These studies found benefits with maintaining normoglycemia. A recent large multicenter study, NICE-SUGAR, compared a similar age-normal with an intermediate glucose target and found the intermediate target superior. These results require explanation.

EVIDENCE ACQUISITION

All published randomized controlled studies on glucose control in ICU were reviewed. The methodological differences between the repeat studies, most specifically NICE-SUGAR, and the original proof-of-concept studies, were systematically analyzed.

EVIDENCE SYNTHESIS

There were important methodological differences, possibly explaining different outcomes. These comprised different target ranges for blood glucose in control and intervention groups, different routes for insulin administration and types of infusion-pumps, different sampling sites, and different accuracies of glucometers, as well as different nutritional strategies and varying levels of expertise.

CONCLUSIONS

These differences do not permit confident recommendations for a single optimal glucose target in variable ICU settings. Respecting the "primum non nocere" principle, it appears safe not to embark on targeting age-normal levels in ICUs that are not equipped to accurately and frequently measure blood glucose and have not acquired extensive experience with iv insulin administration using a customized guideline. A simple overall fall-back position could be to maintain blood glucose levels as close to normal as possible without evoking unacceptable fluctuations, hypoglycemia, and hypokalemia.

Perioperative blood glucose management in patients undergoing tumor hepatectomy

STUDY OBJECTIVE

To determine whether our institutional insulin management (modified Atlanta) protocol is efficient and safe in controlling blood glucose levels in the perioperative period in surgical patients undergoing tumor hepatectomy.

DESIGN

Retrospective study.

SETTING

Large community hospital.

PATIENTS

20 consecutive patients undergoing liver resection for hepatocellular carcinoma, liver metastasis, or other hepatobiliary tumors.

INTERVENTIONS AND MEASUREMENTS

All patients continuously received intravenous glucose (5% dextrose in water, one mL/kg/hr); insulin was administered according to a strict algorithm, and dose adjustments were based on measurements of whole-blood glucose intraoperatively at one-hour intervals, and in the intensive care unit (ICU). Lower and upper blood glucose limits were set at 85 mg/dL and 110 mg/dL, respectively, in the operating room (OR). In the ICU, lower and upper limits were 90 mg/dL and 140 mg/dL, respectively.

MAIN RESULTS

Intraoperatively, 51.3% of measurements were within the target range. In the ICU, 75.2% of measurements showed a blood glucose level of 90 - 140 mg/dL. Two of 78 (2.6%) and two of 363 (0.5%) measurements had a blood glucose level < 70 mg/dL in the OR and ICU, respectively. The lowest blood glucose levels were 65 mg/dL (OR) and 66 mg/dL (ICU).

CONCLUSIONS

The modified Atlanta protocol is efficient and safe in controlling blood glucose levels in the perioperative period of hepatic tumor resection. Because of decreased insulin needs in the ICU, the use of a more liberal algorithm successfully reduced the risk of hypoglycemia.

Comparison of three protocols for tight glycemic control in cardiac surgery patients

OBJECTIVE

We performed a randomized trial to compare three insulin-titration protocols for tight glycemic control (TGC) in a surgical intensive care unit: an absolute glucose (Matias) protocol, a relative glucose change (Bath) protocol, and an enhanced model predictive control (eMPC) algorithm.

RESEARCH DESIGN AND METHODS

A total of 120 consecutive patients after cardiac surgery were randomly assigned to the three protocols with a target glycemia range from 4.4 to 6.1 mmol/l. Intravenous insulin was administered continuously or in combination with insulin boluses (Matias protocol). Blood glucose was measured in 1- to 4-h intervals as requested by the protocols.

RESULTS

The eMPC algorithm gave the best performance as assessed by time to target (8.8 +/- 2.2 vs. 10.9 +/- 1.0 vs. 12.3 +/- 1.9 h; eMPC vs. Matias vs. Bath, respectively; P < 0.05), average blood glucose after reaching the target (5.2 +/- 0.1 vs. 6.2 +/- 0.1 vs. 5.8 +/- 0.1 mmol/l; P < 0.01), time in target (62.8 +/- 4.4 vs. 48.4 +/- 3.28 vs. 55.5 +/- 3.2%; P < 0.05), time in hyperglycemia >8.3 mmol/l (1.3 +/- 1.2 vs. 12.8 +/- 2.2 vs. 6.5 +/- 2.0%; P < 0.05), and sampling interval (2.3 +/- 0.1 vs. 2.1 +/- 0.1 vs. 1.8 +/- 0.1 h; P < 0.05). However, time in hypoglycemia risk range (2.9-4.3 mmol/l) in the eMPC group was the longest (22.2 +/- 1.9 vs. 10.9 +/- 1.5 vs. 13.1 +/- 1.6; P < 0.05). No severe hypoglycemic episode (<2.3 mmol/l) occurred in the eMPC group compared with one in the Matias group and two in the Bath group.

CONCLUSIONS

The eMPC algorithm provided the best TGC without increasing the risk of severe hypoglycemia while requiring the fewest glucose measurements. Overall, all protocols were safe and effective in the maintenance of TGC in cardiac surgery patients.

Tight perioperative glucose control is associated with a reduction in renal impairment and renal failure in non-diabetic cardiac surgical patients

Introduction

Acute renal failure after cardiac surgery increases in-hospital mortality. We evaluated the effect of intra- and postoperative tight control of blood glucose levels on renal function after cardiac surgery based on the Risk, Injury, Failure, Loss, and End-stage kidney failure (RIFLE) criteria, and on the need for acute postoperative dialysis.

Methods

We retrospectively analyzed two groups of consecutive patients undergoing cardiac surgery with cardiopulmonary bypass between August 2004 and June 2006. In the first group, no tight glycemic control was implemented (Control, n = 305). Insulin therapy was initiated at blood glucose levels > 150 mg/dL. In the group with tight glycemic control (Insulin, n = 745), intra- and postoperative blood glucose levels were targeted between 80 to 110 mg/dL, using the Aalst Glycemia Insulin Protocol. Postoperative renal impairment or failure was evaluated with the RIFLE score, based on serum creatinine, glomerular filtration rate and/or urinary output. We used the Cleveland Clinic Severity Score to compare the predicted vs observed incidence of acute postoperative dialysis between groups.

Results

Mean blood glucose levels in the Insulin group were lower compared to the Control group from rewarming on cardiopulmonary bypass onwards until ICU discharge (p < 0.0001). Median ICU stay was 2 days in both groups. In non-diabetics, strict perioperative blood glucose control was associated with a reduced incidence of renal impairment (p = 0.01) and failure (p = 0.02) scoring according to RIFLE criteria, as well as a reduced incidence of acute postoperative dialysis (from 3.9% in Control to 0.7% in Insulin; p < 0.01). The 30-day mortality was lower in the Insulin than in the Control group (1.2% vs 3.6%; p = 0.02), representing a 70% decrease in non-diabetics (p < 0.05) and 56.1% in diabetics (not significant). The observed overall incidence of acute postoperative dialysis was adequately predicted by the Cleveland Clinic Severity Score in the Control group (p = 0.6), but was lower than predicted in the Insulin group (1.2% vs 3%, p = 0.03).

Conclusions

In non-diabetic patients, tight perioperative blood glucose control is associated with a significant reduction in postoperative renal impairment and failure after cardiac surgery according to the RIFLE criteria. In non-diabetics, tight blood glucose control was associated with a decreased need for postoperative dialysis, as well as 30-day mortality, despite of a relatively short ICU stay.