Perioperative tight glucose control with hyperinsulinemic-normoglycemic clamp technique in cardiac surgery

AI powered electrochemical multi-component detection of insulin and glucose in serum

Multi-component detection of insulin and glucose in serum is of great importance and urgently needed in clinical diagnosis and treatment due to its economy and practicability. However, insulin and glucose can hardly be determined by traditional electrochemical detection methods. Their mixed oxidation currents and rare involvement in the reaction process make it difficult to decouple them. In this study, AI algorithms are introduced to power the electrochemical method to conquer this problem. First, the current curves of insulin, glucose, and their mixed solution are obtained using cyclic voltammetry. Then, seven features of the cyclic voltammetry curve are extracted as characteristic values for detecting the concentrations of insulin and glucose. Finally, after training using machine learning algorithms, insulin and glucose concentrations are decoupled and regressed accurately. The entire detection process only takes three minutes. It can detect insulin at the pmol level and glucose at the mmol level, which meets the basic clinical requirements. The average relative error in predicting insulin concentrations is around 6.515%, and that in predicting glucose concentrations is around 4.36%. To verify the performance and effectiveness of the proposed method, it is used to determine the concentrations of insulin and glucose in fetal bovine serum and real clinical serum samples. The results are satisfactory, demonstrating that the method can meet basic clinical needs. This multi-component testing system delivers acceptable detect limit and accuracy and has the merits of low cost and high efficiency, holding great potential for use in clinical diagnosis.

Rapid Advancement in Enteral Nutrition Does Not Affect Systemic Inflammation and Insulin Homeostasis Following Pediatric Cardiopulmonary Bypass Surgery

OBJECTIVES

To determine impact of enteral nutrition delivery on the relationship among inflammation, insulin resistance, and outcomes following pediatric cardiopulmonary bypass surgery.

DESIGN

Pilot, randomized study analyzed according to intention-to-treat analysis.

SETTING

Pediatric cardiac ICU.

PATIENTS

Infants (≤ 6 mo) undergoing cardiopulmonary bypass.

INTERVENTIONS

Patients randomly assigned to receive rapid escalation to enteral nutrition reaching goal feeds by 27 hours or standard feeding practice reaching goal feeds by 63 hours. Feeds were initiated on the first postoperative day.

MEASUREMENTS AND MAIN RESULTS

Fifty patients were randomized equally to study arms. Patients were a median (interquartile range) of 16 days old (7-110 d old), undergoing biventricular surgery (88%) with a median cardiopulmonary bypass time of 125 minutes (105-159 min). Serial blood samples were drawn before and after cardiopulmonary bypass, cardiac ICU admission, and every 12 hours (up to 96 hr) for glucose, insulin, and cytokines (interleukin-1α, interleukin-6, interleukin-8, interleukin-10, and tumor necrosis factor-α) levels. Glucose-insulin ratio was calculated to quantify insulin resistance. Patient characteristics, time to enteral nutrition initiation, enteral nutrition interruptions, and insulin administration were similar across intervention arms. FF reached goal feeds at similar intervals as standard feeding (39 hr [30-60 hr] vs 60 hr [21-78 hr]; p = 0.75). No difference in cytokine, insulin, or glucose-insulin ratio was noted between groups. Higher inflammation was associated with increased glucose-insulin ratio and higher risk of adverse events. In multivariable models of interleukin-8, FF was associated with increased glucose-insulin ratio (estimate of effect [95% CI], 0.152 [0.033-0.272]; p = 0.013). Although higher interleukin-8 was associated with an elevated risk of adverse event, this relationship was possibly mitigated by FF (odds ratio [95% CI], 0.086 [0.002-1.638]; p = 0.13).

CONCLUSIONS

A FF strategy was not associated with changes to early enteral nutrition delivery. Inflammation, insulin resistance, and morbidity were similar, but FF may modify the relationship between inflammation and adverse event. Multicenter nutrition studies are possible and necessary in this vulnerable population.

Parenteral amino acid supplementation with high-dose insulin prevents hypoaminoacidemia during cardiac surgery

OBJECTIVES

Surgery triggers a stress response that produces insulin resistance and hyperglycemia. During cardiac surgery, the administration of high-dose insulin along with dextrose titration maintains normoglycemia, but dramatically decreases plasma amino acids (AAs) compared with preoperative fasting levels. Hypoaminoacidemia limits protein synthesis and prevents anabolic responses after surgery. We investigated whether parenteral infusion of AAs during and immediately after cardiac surgery would prevent hypoaminoacidemia in patients who receive high-dose insulin therapy.

METHODS

Sixteen patients undergoing coronary artery bypass grafting surgery were randomly allocated to receive AAs with % kcal equivalent to either 20% (n = 8) or 35% (n = 8) of their measured resting energy expenditure (REE). Insulin was infused at a constant rate of 5 mU/(kg × min), whereas dextrose was titrated to maintain normoglycemia during and until 5 h after surgery. Plasma AA concentrations were measured at baseline before and after surgery.

RESULTS

Compared with the 20% AA group after surgery, AA concentrations were significantly higher in the 35% AA group for 12 of 20 AAs (P < 0.032), including all branched-chain AAs. In the 20% AA group, total essential AAs decreased by 21% and nonessential AAs decreased by 14% after surgery compared with preoperative fasting levels. In contrast, giving 35% AAs prevented this unfavorable decrease in AAs, and in fact allowed for a 23% and 12% increase in essential and nonessential AAs, respectively.

CONCLUSIONS

AA supplementation at 35% REE, but not 20% REE, can effectively prevent hypoaminoacidemia caused by high-dose insulin therapy during cardiac surgery.

Feeding May Modulate the Relationship Between Systemic Inflammation, Insulin Resistance, and Poor Outcome Following Cardiopulmonary Bypass for Pediatric Cardiac Surgery

BACKGROUND

Hyperglycemia is common following cardiopulmonary bypass (CPB) surgery and is associated with poor outcomes, often attributed to hyperinsulinemia and an acquired state of insulin resistance. This study examined the underpinnings of hyperglycemia and the effects of nutrition on the association with inflammation and clinical outcomes.

METHODS

This prospective, observational cohort study enrolled consecutive children (<18 years) undergoing CPB. Serial measurements of inflammatory cytokines, glucose, insulin, and nutrition delivery were obtained. Glucose-insulin ratio (G:I) was calculated for each time point as a measure of insulin resistance (lower G:I reflects higher resistance). Clinical outcomes were recorded using a composite morbidity score.

RESULTS

The 200 subjects studied were predominantly females (58%) undergoing biventricular repair (85%) at a median (interquartile range) age of 0.58 years (0.28, 3.4) and weight of 7.0 kg (3.1, 59.5). Hyperglycemia was common (49% of patients), coinciding with peak cytokine concentrations. Insulin levels were highest and G:I lowest immediately following separation from CPB but had no consistent relationship with cytokines. The morbidity outcome was reached by 23% of patients, with increased odds associated with higher interleukin (IL)6 and IL8 levels but not by glucose, insulin, or G:I. Providing higher feeding volumes attenuated this association between inflammation and morbidity. Higher feeds were not associated with G:I but appeared to decrease the strength of the relationship between cytokines and glycemic indices.

CONCLUSION

Postoperative morbidity is independently associated with increased inflammation but not with hyperglycemia or markers of insulin resistance. Higher feeding volume may modify these relationships and have a protective role.

Hyperinsulinemic normoglycemia decreases glucose variability during cardiac surgery

PURPOSE

Increased glucose variability may be associated with worse outcomes in critically ill patients. Hyperinsulinemic normoglycemia provides intensive glucose control during surgery and may reduce glucose variability. Our objective was to compare glycemic variability between two methods of glucose control in cardiac surgical patients: hyperinsulinemic normoglycemia vs standard insulin infusion. We also assessed whether the effect differed between patients with and without diabetes mellitus.

METHODS

We compared measures of glycemic variability, including the primary outcome, average real variability (ARV), and secondary outcomes, within-patient standard deviation (SD) and glucose lability index (GLI), in 252 patients who received hyperinsulinemic normoglycemia and 266 patients who received standard therapy. Data was randomly sampled from each patient treated with hyperinsulinemic normoglycemia, so patients in each group had a similar number of glucose measurements. The significance level for each hypothesis was 0.05, and 0.025 within diabetic status.

RESULTS

For nondiabetic patients, hyperinsulinemic normoglycemia reduced mean glucose measure-to-measure variability for ARV by an estimated -0.23 (97.5% CI -0.30, -0.16) mg/dl/min (P < 0.001) versus standard care. There was no difference in glycemic variability between groups for diabetic patients, with difference in means (97.5% CI) of -0.10 (-0.20, 0.02) mg/dl/min, P = 0.07. Mean SD was lower for hyperinsulinemic normoglycemia patients overall, with difference in means (95% CI) of -19 (-22, -16), P < 0.001, with a stronger effect in nondiabetics (interaction P = 0.042). GLI was also lower with hyperinsulinemic normoglycemia.

CONCLUSION

Hyperinsulinemic normoglycemia decreases glucose variability for cardiac surgical patients with a stronger effect in nondiabetic patients.

Insulin resistance and inflammation are a cause of hyperglycemia after pediatric cardiopulmonary bypass surgery

OBJECTIVES

Hyperglycemia is common after pediatric cardiopulmonary bypass (CPB) surgery and is attributed to a state of insulin resistance. We examined the role of CPB-induced inflammation on postoperative plasma glucose, insulin, and the glucose-to-insulin ratio, which was used as a marker of insulin resistance; a decrease in the ratio reflects increased resistance.

METHODS

We conducted an ancillary study on a previously published randomized trial of children undergoing CPB surgery. Serial blood glucose, insulin, and cytokines were drawn after CPB and at selected intervals for up to 48 hours after surgery. The primary outcome was plasma insulin levels and glucose-to-insulin ratio. Glucose delivery and feeding status were monitored for potential modifying effects.

RESULTS

The 299 children studied were predominantly male (55%) with a median age of 2.7 (interquartile range [IQR]: 0.5-6.5) years, and weight of 12.6 (IQR: 6.4-10.8) kg. Operations had a median Society of Thoracic Surgery-European Association for Cardio-Thoracic Surgery complexity score of 1 (IQR: 1-2) and CPB time of 82 (IQR: 58-122) minutes. Hyperglycemia occurred in 85% of subjects; odds of hyperglycemia peaked at 6 hours after CPB. Plasma glucose was associated with increased insulin and a lower glucose-to-insulin ratio. Increased interleukin (IL)-6 concentrations were associated with increased glucose (estimate [EST]: 0.55 (±0.13) mmol/L; P < .001) and insulin (EST: 1.14 (±0.12) μmol/L; P < .001) in linear regression adjusted for repeated measures. Paradoxically, increased cytokines were associated with an increased glucose-to-insulin ratio (EST: 0.21 (±0.03) mmol/μmol; P < .001).

CONCLUSIONS

Hyperglycemia after pediatric CPB surgery is associated with hyperinsulinemia, which may reflect insulin resistance in some patients. Inflammation induced by CPB may play a causative role in insulin resistance.

Glucose and insulin administration while maintaining normoglycemia inhibits whole body protein breakdown and synthesis after cardiac surgery

We investigated the effect of insulin administered as part of a hyperinsulinemic-normoglycemic clamp on protein metabolism after coronary artery bypass grafting (CABG) surgery. Eighteen patients were studied, with nine patients in the control group receiving standard metabolic care and nine patients receiving insulin (5 mU·kg(-1)·min(-1)). Whole body glucose production, protein breakdown, synthesis, and oxidation were determined using stable isotope tracer kinetics (l-[1-(13)C]leucine, [6,6-(2)H2]glucose) before and 6 h after the procedure. Plasma amino acids, cortisol, and lactate were also measured. Endogenous glucose production (preoperatively 10.0 ± 1.6, postoperatively 3.7 ± 2.5 μmol·kg(-1)·min(-1); P = 0.0001), protein breakdown (preoperatively 105.3 ± 9.8, postoperatively 85.2 ± 9.2 mmol·kg(-1)·h(-1); P = 0.0005) and synthesis (preoperatively 88.7 ± 8.7, postoperatively 72.4 ± 8.4 mmol·kg(-1)·h(-1); P = 0.0005) decreased in the presence of hyperinsulinemia, whereas both parameters remained unchanged in the control group. A positive correlation between endogenous glucose production and protein breakdown was observed in the insulin group (r(2) = 0.385). Whole body protein oxidation and balance decreased after surgery in patients receiving insulin without reaching statistical significance. In the insulin group the plasma concentrations of 13 of 20 essential and nonessential amino acids decreased to a significantly greater extent than in the control group. In summary, supraphysiological hyperinsulinemia, while maintaining normoglycemia, decreased whole body protein breakdown and synthesis in patients undergoing CABG surgery. However, net protein balance remained negative.

Preoperative oral rehydration therapy with 2.5 % carbohydrate beverage alleviates insulin action in volunteers

Preoperative carbohydrate loading enhances insulin action by approximately 50 %. In some Japanese hospitals, preoperative oral rehydration therapy is performed for preventing dehydration during surgery. We hypothesized that preoperative oral rehydration therapy with a 2.5 % carbohydrate beverage that is widely used in Japan can enhance insulin action. Therefore, we investigated the effect of this 2.5 % carbohydrate beverage on insulin action in volunteers. Six healthy volunteers participated in this crossover randomized study. The participants were segregated into 2 groups: an oral rehydration therapy with 2.5 % carbohydrate beverage group (group A) and a control group (group B). Subjects in group B were allowed to drink only water from 9 pm the day before the test; conversely, group A fasted from 9 pm onward and drank 500 ml of the beverage containing 2.5 % carbohydrate (OS-1; Otsuka Pharmaceutical Factory, Tokushima, Japan) between 9 and 12 pm and again at 6.30 am. At 8.30 am, a hyperinsulinemic normoglycemic clamp was initiated using an artificial pancreas STG-22 (Nikkiso, Tokyo, Japan). Insulin action was evaluated in both groups using the glucose infusion rate. Blood glucose levels at the initiation of the clamp procedure were similar. However, the glucose infusion rate for group A was significantly higher than that of group B (8.6 ± 1.5 vs. 6.8 ± 2.0 mg/kg/min, p = 0.009). In conclusion, the hyperinsulinemic normoglycemic clamp using an artificial pancreas showed that the administration of a 2.5 % carbohydrate oral rehydration solution for preoperative oral rehydration therapy improves insulin action in volunteers.

Diabetes, perioperative ischaemia and volatile anaesthetics: consequences of derangements in myocardial substrate metabolism

Volatile anaesthetics exert protective effects on the heart against perioperative ischaemic injury. However, there is growing evidence that these cardioprotective properties are reduced in case of type 2 diabetes mellitus. A strong predictor of postoperative cardiac function is myocardial substrate metabolism. In the type 2 diabetic heart, substrate metabolism is shifted from glucose utilisation to fatty acid oxidation, resulting in metabolic inflexibility and cardiac dysfunction. The ischaemic heart also loses its metabolic flexibility and can switch to glucose or fatty acid oxidation as its preferential state, which may deteriorate cardiac function even further in case of type 2 diabetes mellitus.Recent experimental studies suggest that the cardioprotective properties of volatile anaesthetics partly rely on changing myocardial substrate metabolism. Interventions that target at restoration of metabolic derangements, like lifestyle and pharmacological interventions, may therefore be an interesting candidate to reduce perioperative complications. This review will focus on the current knowledge regarding myocardial substrate metabolism during volatile anaesthesia in the obese and type 2 diabetic heart during perioperative ischaemia.

High-dose insulin administration is associated with hypoaminoacidemia during cardiac surgery

Although the effects of insulin on glucose homeostasis are well recognized in surgical patients, its effect on perioperative protein metabolism has received little attention. The purpose of this study was to examine the effect of high-dose insulin therapy on the plasma concentrations of amino acids (AAs) in patients undergoing coronary artery bypass grafting surgery. We studied 20 nondiabetic patients scheduled for elective coronary artery bypass grafting surgery. Patients were randomly allocated to receive either standard metabolic care (target glycemia 6.0-10.0 mmol/L, control group, n = 10) or high-dose insulin therapy (insulin group, n = 10). Insulin was administered at 5 mU·kg(-1)·min(-1) beginning at skin incision. Simultaneously, 20% dextrose was infused at a variable rate adjusted to maintain glycemia between 4.0 and 6.0 mmol/L. Plasma AAs, glucose, cortisol, and insulin were measured immediately before surgery and at sternal closure. Differences in mean values were assessed by Student t test. Plasma concentrations of all AAs decreased in the insulin group, with 15 of 22 AAs, including all branched-chain AAs, being significantly lower at sternal closure when compared with the control group. At the end of surgery, plasma glucose concentration was significantly lower in the insulin group (4.2 ± 0.6 vs 7.3 ± 1.0 mmol/L, P = .0001), whereas plasma cortisol levels did not show any difference between groups. High-dose insulin therapy resulted in a significant reduction in plasma AAs, particularly branched-chain AAs, during cardiac surgery.

Perioperative glucose control: living in uncertain times--Continuing Professional Development

PURPOSE

Hyperglycemia occurs frequently in surgical patients. The objective of this Continuing Professional Development (CPD) module is to review glucose physiology and pathophysiology and provide an update on the practical management of perioperative glucose based on recently published randomized controlled trials (RCTs).

PRINCIPAL FINDINGS

In the mid 2000s, several professional medical organizations recommended the implementation of strict glucose control (glucose concentrations 4.4 to 6.1 mmol·L(-1)). However, the publication of new randomized controlled trials has dampened the initial enthusiasm. While the optimal glucose target range remains a matter of debate, hyperglycemia has been associated with increased morbidity and mortality in a variety of clinical settings. However, strict glucose control is associated with a sixfold increase in episodes of severe hypoglycemia (glucose levels < 2.2 mmol·L(-1)), which has also been linked with increased mortality. For critically ill patients, the American Diabetes Association and the American Association of Clinical Endocrinologists recommend aiming for a blood glucose level from 7.8 to 10.0 mmol·L(-1). While no specific target range can be recommended as yet during major surgery, glucose levels should be kept < 10.0 mmol·L(-1). In critically ill patients, glucose measured from capillary blood may give a falsely elevated value, so arterial blood sampling is preferred when measuring glucose. Frequent arterial blood glucose determination using an arterial blood gas analyzer or an International Organization for Standardization (ISO) 15197-compliant glucometer is crucial to avoid and detect deleterious hypoglycemic episodes.

CONCLUSIONS

Although there is agreement that both hyperglycemia and hypoglycemia are deleterious, there is no consensus on the target glucose values to enhance clinical outcomes.

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.