Efficacy and safety of an insulin infusion protocol during and after cardiac surgery

Impact of early postoperative blood glucose variability on serum endocan level in cardiac surgery patients: a sub study of the ENDOLUNG observational study

BACKGROUND

Early postoperative glycemic variability is associated with worse outcome after cardiac surgery, but the underlying mechanisms remain unknown. This study aimed to describe the relationship between postoperative glycemic variability and endothelial function, as assessed by serum endocan level in cardiac surgery patients.

METHODS

We performed a post hoc analysis of patients included in the single-center observational ENDOLUNG study. Adult patients who underwent planned isolated coronary artery bypass graft surgery were eligible. Postoperative glycemic variability was assessed by calculating the coefficient of variability (CV) of blood glucose measured within 24 (CV24) and 48 (CV48) hours after surgery. Serum endocan level was measured at 24 (Endocan24) and 48 (Endocan48) hours after surgery. Pearson's correlation coefficient with 95% confidence interval (95% CI) was calculated between CV24 and Endocan24, and between CV48 and Endocan48.

RESULTS

Data from 177 patients were analyzed. Median CV24 and CV48 were 18% (range 7 to 39%) and 20% (range 7 to 35%) respectively. Neither CV48 nor CV24 were significantly correlated to Endocan48 and Endocan24 respectively (r (95% CI) = 0.150 (0.001 to 0.290; and r (95% CI) = 0.080 (-0.070 to 0.220), respectively).

CONCLUSIONS

Early postoperative glycemic variability within 48 h after planned cardiac surgery does not appear to be correlated with postoperative serum endocan level.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02542423.

Evaluating the Utilization of a Perioperative Hyperglycemic Protocol: A Quality Improvement Project

PURPOSE

The purpose of this project to evaluate adherence to the perioperative hyperglycemic protocol among Certified Registered Nurse Anesthetists (CRNAs) at a large academic hospital. A secondary objective of this project is CRNAs' perceptions of barriers to point-of-care (POC) testing and the protocol.

DESIGN

A quality improvement project.

METHODS

Using Donabedian's conceptual framework, a Phase 1 retrospective chart analysis of 297 patients with diabetes undergoing noncardiac surgery before and after implementing POC testing for intraoperative glucose control was performed. Only patients with preoperative BG ≥ 180 mg/dL were included in this phase of the project, which involved a comparison of the protocol utilization before and after implementation of POC testing. Phase 2 included an assessment of CRNA's perceptions of the protocol.

FINDINGS

The final sample included 91 (37 preimplementation; 54 postimplementation) participants. There were no significant demographic differences between the groups. Overall, 52.7% of patients had intraoperative glucose checks, and only 16.5% received insulin. Preoperative BG levels decreased 11.4-points, and postoperative BG levels increased 20.4 points when comparing pre- and postimplementation groups. However, there were significant differences in postoperative glucose levels, pre- and postimplementation. The survey showed that the majority (65.5%) of CRNAs identified difficulty locating the protocol as the primary barrier to utilization.

CONCLUSIONS

Although all patients included in this project qualified for an intraoperative glucose check, findings revealed that only half of the patients had a glucose check and less than one fifth of the patients received insulin treatment, indicating poor adherence to the protocol. Thus, while implementing protocols is essential, utilization and adherence to the protocol are critical to improving patient outcomes. Recommendations for continued improvement include increasing protocol accessibility, staff training, compliance monitoring, and a more simple protocol structure.

Perioperative blood glucose variability and autonomic nervous system activity in on-pump cardiac surgery patients: Study protocol of a single-center observational study

INTRODUCTION

On-pump coronary artery bypass graft (CABG) and surgical valve replacement (SVR) are high-risk procedures. Several studies reported that perioperative blood glucose (BG) variability was independently associated with impaired postoperative outcome. However, the underlying mechanisms contributing to increased perioperative BG variability and to its deleterious impact remain unknown. The hypothesis of the study is that perioperative BG variability could be related to perioperative alteration of the autonomic nervous system (ANS) activity and to preoperative BG variability.

METHODS AND ANALYSIS

We designed a prospective observational single-center study. Four groups of 30 patients will be studied: group 1, including insulin-requiring type 2 diabetic patients undergoing on-pump CABG; group 2, including non-insulin-requiring type 2 diabetic patients undergoing on-pump CABG; group 3, including non-diabetic patients undergoing aortic SVR; and group 4, including non-diabetic patient undergoing on-pump CABG. Preoperative (baseline) and postoperative BG variability will be quantified using the Abbott's Freestyle Libre Pro sensor allowing for continuous subcutaneous BG monitoring. Preoperative (baseline) and postoperative ANS activity will be measured using noninvasive continuous heart rate monitoring (Mooky HR memory®). Blood level and urinary concentration of inflammatory and endothelial dysfunction biomarkers will be measured from blood and urinary samples at the end of the surgery and on postoperative day 1 and 2. The primary objective is to describe the relationship between baseline BG variability and postoperative BG variability. The secondary objectives are to describe the relationship: between baseline and postoperative BG variability according to the diabetes phenotype and to the type of surgery; between the ANS activity and the BG variability; and between postoperative BG variability and, urinary and blood biomarkers.

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.

Impact of intravenous exenatide infusion for perioperative blood glucose control on myocardial ischemia-reperfusion injuries after coronary artery bypass graft surgery: sub study of the phase II/III ExSTRESS randomized trial

BACKGROUND

The aim of the study was to investigate whether intravenous (iv) infusion of exenatide, a synthetic GLP-1 receptor agonist, could provide a protective effect against myocardial ischemia-reperfusion injury after coronary artery bypass graft (CABG) surgery.

METHODS

A sub study analysis of patients > 18 years admitted for elective CABG and included in the ExSTRESS trial was conducted. Patients were randomized to receive either iv exenatide (1-h bolus of 0.05 µg min^-1 followed by a constant infusion of 0.025 µg min^-1) (exenatide group) or iv insulin therapy (control group) for blood glucose control (target range 100-139 mg dl^-1) during the first 48 h after surgical incision. All serum levels of troponin I measured during routine care in the Cardiac Surgery ICU were recorded. The primary outcome was the highest value of plasma concentration of troponin I measured between 12 and 24 h after ICU admission. The proportion of patients presenting an echocardiographic left ventricular ejection fraction (LVEF) > 50% at the follow-up consultation was compared between the two groups.

RESULTS

Finally, 43 and 49 patients were analyzed in the control and exenatide groups, respectively {age: 69 [61-76] versus 71 [63-75] years; baseline LVEF < 50%: 6 (14%) versus 16 (32%) patients; on-pump surgery: 29 (67%) versus 33 (67%) patients}. The primary outcome did not significantly differ between the two groups (3.34 [1.06-6.19] µg l^-1 versus 2.64 [1.29-3.85] µg l^-1 in the control and exenatide groups, respectively; mean difference (MD) [95% confidence interval (95% CI)] 0.16 [- 0.25; 0.57], p = 0.54). The highest troponin value measured during the first 72 h in the ICU was 6.34 [1.36-10.90] versus 5.04 [2.39-7.18] µg l^-1, in the control and exenatide groups respectively (MD [95% CI] 0.20 [- 0.22; 0.61], p = 0.39). At the follow-up consultation, 5 (12%) versus 8 (16%) patients presented a LVEF < 50% in the control and in the exenatide groups respectively (relative risk [95% CI] 0.68 [0.16; 2.59], p = 0.56).

CONCLUSIONS

Postoperative iv exenatide did not provide any additional cardioprotective effect compared to iv insulin in low-risk patients undergoing scheduled CABG surgery. Trial registration ClinicalTrials.gov Identifier NCT01969149, date of registration: January 7th, 2015; EudraCT No. 2009-009254-25 A, date of registration: January 6th, 2009.

Clinical Effectiveness of Intravenous Exenatide Infusion in Perioperative Glycemic Control after Coronary Artery Bypass Graft Surgery

Background

We aimed to assess the clinical effectiveness of intravenous exenatide compared to insulin in perioperative blood glucose control in coronary artery bypass grafting surgery patients.

Methods

Patients more than 18 yr old admitted for elective coronary artery bypass grafting were included in a phase II/III nonblinded randomized superiority trial. Current insulin use and creatinine clearance of less than 60 ml/min were exclusion criteria. Two groups were compared: the exenatide group, receiving exenatide (1-h bolus of 0.05 µg/min followed by a constant infusion of 0.025 µg/min), and the control group, receiving insulin therapy. The blood glucose target range was 100 to 139 mg/dl. The primary outcome was the proportion of patients who spent at least 50% of the study period within the target range. The consumption of insulin (Cinsulin) and the time to start insulin (Tinsulin) were compared between the two groups.

Results

In total, 53 and 51 patients were included and analyzed in the exenatide and control groups, respectively (age: 70 ± 9 vs. 68 ± 11 yr; diabetes mellitus: 12 [23%] vs. 10 [20%]). The primary outcome was observed in 38 (72%) patients in the exenatide group and in 41 (80%) patients in the control group (odds ratio [95% CI] = 0.85 [0.34 to 2.11]; P = 0.30). Cinsulin was significantly lower (60 [40 to 80] vs. 92 [63 to 121] U, P &lt; 0.001), and Tinsulin was significantly longer (12 [7 to 16] vs. 7 [5 to 10] h, P = 0.02) in the exenatide group.

Conclusions

Exenatide alone at the dose used was not enough to achieve adequate blood glucose control in coronary artery bypass grafting patients, but it reduces overall consumption of insulin and increases the time to initiation of insulin.

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 potential role of glucagon-like peptide-1 or its analogues in enhancing glycaemic control in critically ill adult patients

Intravenous insulin therapy is the gold standard therapy for glycaemic control in hyperglycaemic critically ill adult patients. However, hypoglycaemia remains a major concern in critically ill patients, even in some populations who are not receiving infused insulin. Furthermore, the influence of factors such as glycaemic variability and nutritional support may conceal any benefit of strict glycaemic control on morbidity and mortality in these patients. The recently revised guidelines of the American Diabetic Association/American College of Clinical Endocrinologists no longer advocate very tight glycaemic control or normalization of glucose levels in all critically ill patients. In the light of various concerns over the optimal glucose level and means to achieve such control, the use of glucagon-like peptide-1 or its analogues administered intravenously may represent an interesting therapeutic option.