Insulin therapy in critically ill patients

Nurse-led implementation of a safe and effective intravenous insulin protocol in a medical intensive care unit

BACKGROUND

Recent evidence has linked tight glucose control to worsened clinical outcomes among adults in intensive care units.

OBJECTIVE

To evaluate the effectiveness and safety of a nurse-led intravenous insulin protocol designed to achieve conservative blood glucose control in patients in a medical intensive care unit.

METHODS

A nurse-led intravenous insulin protocol was developed, targeting blood glucose levels at 110 to 149 mg/dL. Hypoglycemia was defined as a blood glucose level less than 70 mg/dL. Patients admitted to the medical intensive care unit who required an insulin infusion were enrolled in the study. Blood glucose levels in those patients were compared with levels in 153 historical control patients admitted to the unit in the 12 months before the protocol was implemented who required an insulin infusion.

RESULTS

Ninety-six patients were enrolled and treated with the protocol. The protocol and control groups had similar characteristics at baseline. More measurements in the protocol group than in the control group (46.3% vs 36.1%, P<.001) were within the target glucose range (110-149 mg/dL). Hyperglycemia (blood glucose ≥200 mg/dL) occurred less often in the protocol group than in the control group (14.8% vs 20.1%, P=.003). Hypoglycemic events (blood glucose <70 mg/dL) also occurred less often in the protocol group (0.07% vs 0.83%, P<.001).

CONCLUSIONS

Implementation of a nurse-led, conservative intravenous insulin protocol in the medical intensive care unit is effective and safe and markedly reduces the rate of hypoglycemia.

Implementation of tight glucose control for critically ill surgical patients: a process improvement analysis

BACKGROUND

Tight glucose control has been advocated as a method to improve outcomes of surgical critical care. However, continuous infusion of insulin has potential morbidity (e.g., neurologic consequences of hypoglycemia), and it remains unclear to what degree the glucose concentration must be controlled. We examined our performance in instituting a protocol for tight glucose control in our surgical intensive care unit (ICU).

METHODS

Prospective study of 220 consecutive patients (February, 2003-March, 2006) who received an infusion of insulin for glucose control for >24 h by protocol. Data collected included age, acuity (Acute Physiology and Chronic Health Evaluation [APACHE] III) score, sex, history of diabetes mellitus, organ dysfunction (Marshall), and death or survival. Infusion-related data included initial glucose concentration, time to glucose <120 mg/dL, h/day of glucose <110 mg/dL and <140 mg/dL, duration of infusion (days), insulin units/day, year of therapy, and complications. Analysis was performed by chi(2), analysis of variance, and logistic regression, with p < 0.05 considered significant.

RESULTS

Insulin drips were required by 10.2% of patients (287/2,804); 29 of these (10.1%) had diabetes mellitus. The mean APACHE III score for the treated patients was 77 +/- 2 (standard deviation), and the mortality rate was 24%. Hypoglycemia (<60 mg/dL) occurred in 4.2% of patients. The trigger insulin concentration decreased over time (2003 vs. 2005) from 249 +/- 14 to 160 +/- 5 mg/dL, and the h/day of glucose <140 increased from 11 +/- 1 to 16 +/- 1. However, age, acuity, APACHE III, days of insulin, time to achieve glucose <120, h/day of glucose <110, and mortality rate were unchanged. By logistic regression, only the year of treatment (odds ratio [OR] 1.871; 95% confidence interval [CI] 1.177, 2.972; p = 0.008] predicted success in controlling the blood glucose concentration to <140 mg/dL; age, illness severity, diabetes history, and trigger glucose concentration [OR 0.996; 95% CI 0.992, 1.001; p = 0.11] did not.

CONCLUSIONS

Success in implementing tight glucose control was modest, albeit improving, despite a specific protocol for administration. No medical reason could be identified for inability to achieve tight glucose control; therefore, successful implementation must be volitional. Education, particularly regarding hypoglycemia, and possible refinement of our protocol may improve our ability to control blood glucose in our ICU.

Tight glycaemic control: a prospective observational study of a computerised decision-supported intensive insulin therapy protocol

INTRODUCTION

A single centre has reported that implementation of an intensive insulin protocol, aiming for tight glycaemic control (blood glucose 4.4 to 6.1 mmol/l), resulted in significant reduction in mortality in longer stay medical and surgical critically ill patients. Our aim was to determine the degree to which tight glycaemic control can be maintained using an intensive insulin therapy protocol with computerized decision support and to identify factors that may be associated with the degree of control.

METHODS

At a general adult 22-bed intensive care unit, we implemented an intensive insulin therapy protocol in mechanically ventilated patients, aiming for a target glucose range of 4.4 to 6.1 mmol/l. The protocol was integrated into the computerized information management system by way of a decision support program. The time spent in each predefined blood glucose band was estimated, assuming a linear trend between measurements.

RESULTS

Fifty consecutive patients were investigated, involving analysis of 7,209 blood glucose samples, over 9,214 hours. The target tight glycaemic control band (4.4 to 6.1 mmol/l) was achieved for a median of 23.1% of the time that patients were receiving intensive insulin therapy. Nearly half of the time (median 48.5%), blood glucose was within the band 6.2 to 7.99 mmol/l. Univariate analysis revealed that body mass index (BMI), Acute Physiology and Chronic Health Evaluation (APACHE) II score and previous diabetes each explained approximately 10% of the variability in tight glycaemic control. BMI and APACHE II score explained most (27%) of the variability in tight glycaemic control in the multivariate analysis, after adjusting for age and previous diabetes.

CONCLUSION

Use of the computerized decision supported intensive insulin therapy protocol did result in achievement of tight glycaemic control for a substantial percentage of each patient's stay, although it did deliver 'normoglycaemia' (4.4 to about 8 mmol/l) for nearly 75% of the time. Tight glycaemic control was difficult to achieve in critically ill patients using this protocol. More sophisticated methods such as continuous blood glucose monitoring with automated insulin and glucose infusion adjustment may be a more effective way to achieve tight glycaemic control. Glycaemia in patients with high BMI and APACHE II scores may be more difficult to control using intensive insulin therapy protocols. Trial registration number 05/Q0505/1.

A review of the use of insulin protocols to maintain normoglycaemia in high dependency patients

AIM

This paper critically examines the evidence base for and issues involved in the introduction of an insulin protocol to maintain normoglycaemia in patients within a medical/surgical high dependency ward.

BACKGROUND

A growing body of evidence has linked hyperglycaemia to worsened clinical outcomes. This has led to intravenous insulin protocols becoming a new standard of care in intensive care units. However, the use and benefits of insulin protocols within high dependency units have not yet been addressed in the literature.

METHODS

The literature was examined for the 10-year period up to January 2005. The databases searched were MEDLINE, OVID, CINHAL, the British Nursing Index, the EBSCO collection, the COCHRANE library, the Department of Health, and guidelines within the Scottish Intercollegiate Guidelines Network and National Institute for Clinical Excellence using the key words insulin, protocol, hyperglycaemia, critical care, intensive care and high dependency.

RESULTS

The literature reports that both medical and surgical intensive care patients treated with intravenous insulin protocols to maintain normoglycaemia experienced significantly reduced mortality and morbidity. Resulting hypoglycaemic episodes were limited with no incidence of patient deterioration. A review of published intravenous insulin protocols used in intensive care settings revealed their safe and effective use in nurse to patient ratios similar to those present in high dependency units.

CONCLUSIONS

In the light of this evidence, it would seem safe and ethically correct to enable high dependency patients to benefit from this cheap intervention. An insulin protocol tailored for the glycaemic control of high dependency patients has been suggested, although it may have to be commenced in conjunction with other fluid and nutrition protocols to safeguard the risk of hypoglycaemic events. Further research into the safety and benefit of insulin protocols in high dependency populations is required.

RELEVANCE TO CLINICAL PRACTICE

The stress of critical illness often leads to hyperglycaemia, which is linked to worsened clinical outcomes. Both medical and surgical intensive care patients treated with intravenous insulin protocols to maintain normoglycaemia experienced significantly reduced mortality and morbidity. This paper identifies that, to date, no research into the benefits of glycaemic control in high dependency populations has been published. The case for the introduction of insulin protocols into high dependency units is therefore examined and an insulin protocol suggested.