Hypoglycemia in the critically ill: how low is too low?

Pulmonary pathogenesis in a murine model of inhaled arsenical exposure

Arsenic trioxide (ATO), an inorganic arsenical, is a toxic environmental contaminant. It is also a widely used chemical with industrial and medicinal uses. Significant public health risk exists from its intentional or accidental exposure. The pulmonary pathology of acute high dose exposure is not well defined. We developed and characterized a murine model of a single inhaled exposure to ATO, which was evaluated 24 h post-exposure. ATO caused hypoxemia as demonstrated by arterial blood-gas measurements. ATO administration caused disruption of alveolar-capillary membrane as shown by increase in total protein and IgM in the bronchoalveolar lavage fluid (BALF) supernatant and an onset of pulmonary edema. BALF of ATO-exposed mice had increased HMGB1, a damage-associated molecular pattern (DAMP) molecule, and differential cell counts revealed increased neutrophils. BALF supernatant also showed an increase in protein levels of eotaxin/CCL-11 and MCP-3/CCL-7 and a reduction in IL-10, IL-19, IFN-γ, and IL-2. In the lung of ATO-exposed mice, increased protein levels of G-CSF, CXCL-5, and CCL-11 were noted. Increased mRNA levels of TNF-a, and CCL2 in ATO-challenged lungs further supported an inflammatory pathogenesis. Neutrophils were increased in the blood of ATO-exposed animals. Pulmonary function was also evaluated using flexiVent. Consistent with an acute lung injury phenotype, respiratory and lung elastance showed significant increase in ATO-exposed mice. PV loops showed a downward shift and a decrease in inspiratory capacity in the ATO mice. Flow-volume curves showed a decrease in FEV0.1 and FEF50. These results demonstrate that inhaled ATO leads to pulmonary damage and characteristic dysfunctions resembling ARDS in humans.

Glucometrics in the first week of critical illness and its association with mortality

OBJECTIVE

Evaluation of glucometrics in the first week of ICU stay and its association with outcomes.

DESIGN

Prospective observational study.

SETTING

Mixed ICU of teaching hospital.

PATIENTS

Adults initiated on insulin infusion for 2 consecutive blood glucose (BG) readings ≥180mg/dL.

MAIN VARIABLES OF INTEREST

Glucometrics calculated from the BG of first week of admission: hyperglycemia (BG>180mg/dL) and hypoglycemia (BG<70mg/dL) episodes; median, standard deviation (SD) and coefficient of variation (CV) of BG, glycemic lability index (GLI), time in target BG range (TIR). Factors influencing glucometrics and the association of glucometrics to patient outcomes analyzed.

RESULTS

A total of 5762 BG measurements in 100 patients of median age 55 years included. Glucometrics: hyperglycemia: 2253 (39%), hypoglycemia: 28 (0.48%), median BG: 169mg/dL (162-178.75), SD 31mg/dL (26-38.75), CV 18.6% (17.1-22.5), GLI: 718.5 [(mg/dL)²/h]/week (540.5-1131.5) and TIR 57% (50-67). Diabetes and higher APACHE II score were associated with higher SD and CV, and lower TIR. On multivariate regression, diabetes (p=0.009) and APACHE II score (p=0.016) were independently associated with higher SD. Higher SD and CV were associated with less vasopressor-free days; lower TIR with more blood-stream infections (BSI). Patients with higher SD, CV and GLI had a higher 28-day mortality. On multivariate analysis, GLI alone was associated with a higher mortality (OR 2.99, p=0.04).

CONCLUSIONS

Glycemic lability in the first week in ICU patients receiving insulin infusion is associated with higher mortality. Lower TIR is associated with more blood stream infections.

Risk and reward: extending stochastic glycaemic control intervals to reduce workload

Background

STAR is a model-based, personalised, risk-based dosing approach for glycaemic control (GC) in critically ill patients. STAR provides safe, effective control to nearly all patients, using 1–3 hourly measurement and intervention intervals. However, the average 11–12 measurements per day required can be a clinical burden in many intensive care units. This study aims to significantly reduce workload by extending STAR 1–3 hourly intervals to 1 to 4-, 5-, and 6-hourly intervals, and evaluate the impact of these longer intervals on GC safety and efficacy, using validated in silico virtual patients and trials methods. A Standard STAR approach was used which allowed more hyperglycaemia over extended intervals, and a STAR Upper Limit Controlled approach limited nutrition to mitigate hyperglycaemia over longer intervention intervals.

Results

Extending STAR from 1–3 hourly to 1–6 hourly provided high safety and efficacy for nearly all patients in both approaches. For STAR Standard, virtual trial results showed lower % blood glucose (BG) in the safe 4.4–8.0 mmol/L target band (from 83 to 80%) as treatment intervals increased. Longer intervals resulted in increased risks of hyper- (15% to 18% BG > 8.0 mmol/L) and hypo- (2.1% to 2.8% of patients with min. BG < 2.2 mmol/L) glycaemia. These results were achieved with slightly reduced insulin (3.2 [2.0 5.0] to 2.5 [1.5 3.0] U/h) and nutrition (100 [85 100] to 90 [75 100] % goal feed) rates, but most importantly, with significantly reduced workload (12 to 8 measurements per day). The STAR Upper Limit Controlled approach mitigated hyperglycaemia and had lower insulin and significantly lower nutrition administration rates.

Conclusions

The modest increased risk of hyper- and hypo-glycaemia, and the reduction in nutrition delivery associated with longer treatment intervals represent a significant risk and reward trade-off in GC. However, STAR still provided highly safe, effective control for nearly all patients regardless of treatment intervals and approach, showing this unique risk-based dosing approach, modulating both insulin and nutrition, to be robust in its design. Clinical pilot trials using STAR with different measurement timeframes should be undertaken to confirm these results clinically.

Estimating the utility value of hypoglycaemia according to severity and frequency using the visual analogue scale (VAS) and time trade-off (TTO) survey

OBJECTIVES

The primary objective of this study was to estimate the health utility values for hypoglycaemia events according to their severity and frequency. The secondary objective was to compare the health utilities between those with Type 2 Diabetes Mellitus and the general population.

METHOD

The health utilities of hypoglycaemia event were measured using Visual Analogue Scale (VAS) and Time Trade-Off (TTO) methods among conveniently sampled consenting adults (>18 years and literate in either English or Malay language), which were then divided into two groups: those in the general population (GP) and those with Type 2 Diabetes Mellitus (T2DM). Each respondent was required to value 13 different health states, including frequencies of daytime hypoglycaemia and nocturnal hypoglycaemia, each depending on its severity (non-severe or severe).

RESULTS

256 respondents from the GP and 99 respondents with T2DM completed the survey. The T2DM group gave higher VAS-values compared to the GP group. The highest mean VAS-utility value for non-severe nocturnal hypoglycaemia occurring once monthly was 0.543 (SD 0.161), and for severe daytime hypoglycaemia occurring once quarterly was 0.293 (SD 0.162) which was the lowest utility value compared to other health states. However, non-severe nocturnal hypoglycaemia occurring once quarterly was 0.537 (SD 0.284) and has the highest TTO-utility value. Severe nocturnal hypoglycaemia occurring once quarterly has the lowest utility value which was -0.104 (SD 0.380). Daytime hypoglycaemia has lower utility value compared to nocturnal hypoglycaemia. Severe hypoglycaemia has a greater disutility compared with the non-severe hypoglycaemia in both studied groups.

CONCLUSION

The findings show that as a health utility, hypoglycaemia has a substantial impact on utility with severe hypoglycaemia having a greater negative impact compared to non-severe events across the board. This highlights the importance of preventing development of severe hypoglycaemia in patients with Type 2 Diabetes Mellitus at any time of the day.

Lower Glucose Target Is Associated With Improved 30-Day Mortality in Cardiac and Cardiothoracic Patients

BACKGROUND

Practice guidelines recommend against intensive insulin therapy in patients who are critically ill based on trials that had high rates of severe hypoglycemia. Intermountain Healthcare uses a computerized IV insulin protocol that allows choice of blood glucose (BG) targets (80-110 vs 90-140 mg/dL) and has low rates of severe hypoglycemia. We sought to study the effects of BG target on mortality in adult patients in cardiac ICUs that have very low rates of severe hypoglycemia.

METHODS

Critically ill patients receiving IV insulin were treated with either of two BG targets (80-110 vs 90-140 mg/dL). We created a propensity score for BG target using factors thought to have influenced clinicians' choice, and then we performed a propensity score-adjusted regression analysis for 30-day mortality.

RESULTS

There were 1,809 patients who met inclusion criteria. Baseline patient characteristics were similar. Median glucose was lower in the 80-110 mg/dL group (104 vs 122 mg/dL, P < .001). Severe hypoglycemia occurred at very low rates in both groups (1.16% vs 0.35%, P = .051). Unadjusted 30-day mortality was lower in the 80-110 mg/dL group (4.3% vs 9.2%, P < .001). This remained after propensity score-adjusted regression (OR, 0.65; 95% CI, 0.43-0.98; P = .04).

CONCLUSIONS

Tight glucose control can be achieved with low rates of severe hypoglycemia and is associated with decreased 30-day mortality in a cohort of largely patients in cardiac ICUs. Although such findings should not be used to guide clinical practice at present, the use of tight glucose control should be reexamined using a protocol that has low rates of severe hypoglycemia.

Co-trimoxazole-induced hypoglycaemia in an immunosuppressed intensive care patient

An 18-year-old female inpatient on a neurosciences intensive care unitwith new onset super-refractory epilepsy became hypoglycaemic 48 h after commencing co-trimoxazole. She had been placed on this for prophylaxis against Pneumocystis jiroveci infection in the context of significant immunosuppression with high-dose corticosteroid therapy. In order to maintain glucose control, she required a continuous infusion of 10% dextrose at rates of 15–25 ml/h. Recurrent attempts to wean this were limited by further hypoglycaemia, until she spontaneously regained normoglycaemia after 73 days. This case report will discuss this unusual case of refractory hypoglycaemia, and the proposed pathophysiology of hypoglycaemia related to co-trimoxazole therapy.

Can HbA1c detect undiagnosed diabetes in acute medical hospital admissions?

OBJECTIVE

To study hyperglycaemia in acute medical admissions to Irish regional hospital.

RESEARCH DESIGN AND METHODS

From 2005 to 2007, 2061 white Caucasians, aged >18 years, were admitted by 1/7 physicians. Those with diabetes symptoms/complications but no previous record of hyperglycaemia (n=390), underwent OGTT with concurrent HbA1c in representative subgroup (n=148). Comparable data were obtained for 108 primary care patients at risk of diabetes.

RESULTS

Diabetes was diagnosed immediately by routine practice in 1% (22/2061) [aged 36 (26-61) years (median IQ range)/55% (12/22) male] with pre-existing diabetes/dysglycaemia present in 19% (390/2061) [69 (58-80) years/60% (235/390) male]. Possible diabetes symptoms/complications were identified in 19% [70 (59-79) years/57% (223/390) male] with their HbA1c similar to primary care patients [54 (46-61) years], 5.7 (5.3-6.0)%/39 (34-42)mmol/mol (n=148) vs 5.7 (5.4-6.1)%/39 (36-43)mmol/mol, p=0.35, but lower than those diagnosed on admission, 10.2 (7.4-13.3)%/88 (57-122)mmol/mol, p<0.001. Their fasting plasma glucose (FPG) was similar to primary care patients, 5.2 (4.8-5.7) vs 5.2 (4.8-5.9) mmol/L, p=0.65, but 2hPG higher, 9.0 (7.3-11.4) vs 5.5 (4.4-7.5), p<0.001. HbA1c identified diabetes in 10% (15/148) with 14 confirmed on OGTT but overall 32% (48/148) were in diabetic range on OGTT. The specificity of HbA1c in 2061 admissions was similar to primary care, 99% vs 96%, p=0.20, but sensitivity lower, 38% vs 93%, p<0.001 (63% on FPG/23% on 2hPG, p=0.037, in those with possible symptoms/complications).

CONCLUSION

HbA1c can play a diagnostic role in acute medicine as it diagnosed another 2% of admissions with diabetes but the discrepancy in sensitivity shows that it does not reflect transient/acute hyperglycaemia resulting from the acute medical event.

Glucose control in critical care

Glycemic control among critically-ill patients has been a topic of considerable attention for the past 15 years. An initial focus on the potentially deleterious effects of hyperglycemia led to a series of investigations regarding intensive insulin therapy strategies that targeted tight glycemic control. As knowledge accumulated, the pursuit of tight glycemic control among critically-ill patients came to be seen as counterproductive, and moderate glycemic control came to dominate as the standard practice in intensive care units. In recent years, there has been increased focus on the importance of hypoglycemic episodes, glycemic variability, and premorbid diabetic status as factors that contribute to outcomes among critically-ill patients. This review provides a survey of key studies on glucose control in critical care, and aims to deliver perspective regarding glycemic management among critically-ill patients.

Glucose control positively influences patient outcome: A retrospective study

OBJECTIVE

The goal of this research is to demonstrate that well-regulated glycemia is beneficial to patient outcome, regardless of how it is achieved.

METHODS

This analysis used data from 1701 patients from 2, independent studies. Glycemic outcome was measured using cumulative time in band (cTIB), calculated for 3 glycemic bands and for threshold values of t = 0.5, 0.6, 0.7, and 0.8. For each day of intensive care unit stay, patients were classified by cTIB, threshold, and hospital mortality, and odds of living (OL) and odds ratio were calculated.

RESULTS

The OL given cTIB ≥ t is higher than the OL given cTIB <t for all values of t, every day, for all 3 glycemic bands studied. The difference between the odds clearly increased over intensive care unit stay for t>0.6. Higher cTIB thresholds resulted in larger increases to odds ratio over time and were particularly significant for the 4.0 to 7.0 mmol/L glycemic band.

CONCLUSION

Increased cTIB was associated with higher OL. These results suggest that effective glycemic control positively influences patient outcome, regardless of how the glycemic regulation is achieved. Blood glucose < 7.0 mmol/L is associated with a measurable increase in the odds of survival, if hypoglycemia is avoided.

The association of oxidative stress and pro-inflammatory cytokines in diabetic patients with hyperglycemic crisis

AIMS

To investigate the relationship between oxidative stress and serum levels of pro-inflammatory cytokines in diabetic patients with hyperglycemic crisis.

METHODS

Seventy-three patients presenting to hospital with diabetic ketoacidosis or non-ketotic hyperglycemia were studied. Superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, total antioxidant capacity (TAC), 8-iso-prostaglandin F2α (8-iso-prostaglandinF2α, 8-iso-PGF2α), tumor necrosis factor receptor-I (TNF-RI), interleukin -1β (IL-1β), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were measured in all patients. The patients were then given an intravenous infusion of insulin 0.1U • kg-1 • h-1, as well as fluids, symptomatic therapy and parenteral and intravenous nutrition.

RESULTS CONCLUSION

Patients with hyperglycemic crises have significantly increased oxidative stress and dysregulated serum pro-inflammatory cytokines that can be effectively treated by intensive insulin therapy.

The effectiveness of a computerized IV infusion protocol to treat hyperglycemia in burn patients

Tight glucose control (TGC) in critical care settings is becoming increasingly the standard of care. However, TGC comes with the risk of hypoglycemia, as highlighted by some recent studies. Our aim was to establish TGC in burn patients without increasing rates of hypoglycemia. The authors used a computer-driven glucose control program (CGS) to achieve this goal. The computer program calculates insulin drip rates by using a multiplier that changes according to blood glucose (BG) values as well as trends and keeps a record of BG data and insulin infusion rates for future quality control analysis. CGS is also a useful adjunct in transitioning patients from an IV insulin drip to subcutaneous insulin. A retrospective review of the glucose control program database was performed to obtain information on length of time to goal glucose levels (set at 100-150 mg/dl), glucose level trends, and incidence of hypoglycemia when using the computer program. Over 18 months, we used CGS on 94 critical and noncritical burn patients. Mean time to target BG was 5.1 hours. Glucose levels of 100 to 150 mg/dl were maintained 63.3% of the time, and values within the wider range of 70 to 150 mg/dl were maintained 80.8% of the time. The incidence of hypoglycemia, defined as BG level below 70 mg/dl, was only 1.66% and was treated without any adverse sequelae. Hyperglycemic episodes were directly correlated with surgical interventions during which time the CGS was not utilized in the operating room. CGS offers a safe and effective means of rapidly achieving and maintaining glucose targets in burn patients. Further analysis of the data needs to be conducted to determine whether the BG targets used in our study offer a morbidity benefit to burn patients.

First pilot trial of the STAR-Liege protocol for tight glycemic control in critically ill patients

Tight glycemic control (TGC) has shown benefits in ICU patients, but been difficult to achieve consistently due to inter- and intra- patient variability that requires more adaptive, patient-specific solutions. STAR (Stochastic TARgeted) is a flexible model-based TGC framework accounting for patient variability with a stochastically derived maximum 5% risk of blood glucose (BG) below 72 mg/dL. This research describes the first clinical pilot trial of the STAR approach and the post-trial analysis of the models and methods that underpin the protocol. The STAR framework works with clinically specified targets and intervention guidelines. The clinically specified glycemic target was 125 mg/dL. Each trial was 24 h with BG measured 1-2 hourly. Two-hourly measurement was used when BG was between 110-135 mg/dL for 3 h. In the STAR approach, each intervention leads to a predicted BG level and outcome range (5-95th percentile) based on a stochastic model of metabolic patient variability. Carbohydrate intake (all sources) was monitored, but not changed from clinical settings except to prevent BG<100 mg/dL when no insulin was given. Insulin infusion rates were limited (6 U/h maximum), with limited increases based on current infusion rate (0.5-2.0 U/h), making this use of the STAR framework an insulin-only TGC approach. Approval was granted by the Ethics Committee of the Medical Faculty of the University of Liege (Liege, Belgium). Nine patient trials were undertaken after obtaining informed consent. There were 205 measurements over all 9 trials. Median [IQR] per-patient results were: BG: 138.5 [130.6-146.0]mg/dL; carbohydrate administered: 2-11 g/h; median insulin:1.3 [0.9-2.4]U/h with a maximum of 6.0 [4.7-6.0]U/h. Median [IQR] time in the desired 110-140 mg/dL band was: 50.0 [31.2-54.2]%. Median model prediction errors ranged: 10-18%, with larger errors due to small meals and other clinical events. The minimum BG was 63 mg/dL and no other measurement was below 72 mg/dL, so only 1 measurement (0.5%) was below the 5% guaranteed minimum risk level. Post-trial analysis showed that patients were more variable than predicted by the stochastic model used for control, resulting in some of the prediction errors seen. Analysis and (validated) virtual trial re-simulating the clinical trial using stochastic models relevant to the patient's particular day of ICU stay were seen to be more accurate in capturing the observed variability. This analysis indicated that equivalent control and safety could be obtained with similar or lower glycemic variability in control using more specific stochastic models. STAR effectively controlled all patients to target. Observed patient variability in response to insulin and thus prediction errors were higher than expected, likely due to the recent insult of cardiac surgery or a major cardiac event, and their immediate recovery. STAR effectively managed this variability with no hypoglycemia. Improved stochastic models will be used to prospectively test these outcomes in further ongoing clinical pilot trials in this and other units.

Glucose Control in Critical Care Oncology

The optimal strategy for glucose control in critically ill patients remains controversial and may vary depending on their diagnostic groups. This retrospective study addresses this question in a cohort of critically ill oncology patients. Serial blood glucose levels were measured in a specialist oncology intensive care unit (ICU) in England between January 2009 and May 2010. Intravenous sliding scale insulin was started when blood glucose levels were greater than 8.3 mmol/L, aiming for a target glucose level below 10 mmol/L. There were 565 patients admitted to the ICU, of whom 181 (32%) were medical and 384 (68%) surgical. The mean blood glucose was 7.8 mmol/L. Mortality rates relative to mean glucose levels followed a U-shaped curve. There was a statistically significant increase in mortality among patients who spent longer periods with blood glucose levels less than 6 mmol/L, and those whose glucose was greater than 10 mmol/L (20% vs 7.3%; p <0.001). Fluctuations in blood glucose levels measured by the coefficient of variation against mean glucose levels demonstrated a significant increase in mortality in patients with higher variability (p<0.01). Higher coefficients of variation were also associated with an increased length of ICU stay and increased readmission rates to ICU. In this study, hypoglycaemia, hyperglycaemia and increased variability in glucose levels were each independently associated with worse outcomes in critically ill patients.

Second pilot trials of the STAR-Liege protocol for tight glycemic control in critically ill patients

BACKGROUND

Critically ill patients often present increased insulin resistance and stress-induced hyperglycemia. Tight glycemic control aims to reduce blood glucose (BG) levels and variability while ensuring safety from hypoglycemia. This paper presents the results of the second Belgian clinical trial using the customizable STAR framework in a target-to-range control approach. The main objective is reducing measurement frequency while maintaining performance and safety of the glycemic control.

METHODS

The STAR-Liege 2 (SL2) protocol targeted the 100-140 mg/dL glycemic band and offered 2-hourly and 3-hourly interventions. Only insulin rates were adjusted, and nutrition inputs were left to the attending clinicians. This protocol restricted the forecasted risk of BG < 90 mg/dL to a 5% level using a stochastic model of insulin sensitivity to assess patient-specific responses to insulin and its future likely variability to optimize insulin interventions. The clinical trial was performed at the Centre Hospitalier Universitaire de Liege and included 9 patients. Results are compared to 24-hour pre-trial and 24-hour post-trial, but also to the results of the first pilot trial performed in Liege, STAR-Liege 1 (SL1). This trial was approved by the Ethics Committee of the Medical Faculty of the University of Liege (Liege, Belgium).

RESULTS

During the SL2 trial, 91 measurements were taken over 194 hours. BG levels were tightly distributed: 54.9% of BG within 100-140 mg/dL, 40.7% were ≥ 140 mg/dL and 4.4% were < 100 mg/dL with no BG < 70 mg/dL. Comparing these results with 24-hour pre-trial and post-trial shows that SL2 reduced high and low BG levels and reduced glycemic variability. Nurses selected 3-hourly measurement only 5 of 16 times and overrode 12% of 91 recommended interventions (35% increased insulin rates and 65% decreased insulin rates). SL1 and SL2 present similar BG levels distribution (p > 0.05) with significantly reduced measurement frequency for SL2 (p < 0.05).

CONCLUSIONS

The SL2 protocol succeeded in reducing clinical workload while maintaining safety and effectiveness of the glycemic control. SL2 was also shown to be safer and tighter than hospital control. Overall results validate the efficacy of significantly customizing the STAR framework.

The relationship between oxidative stress and the levels of serum circulating adhesion molecules in patients with hyperglycemia crises

OBJECTIVE

To investigate the relationship between oxidative stress and the levels of serum circulating adhesion molecules in patients with hyperglycemia crises.

METHODS

A total of 73 patients with diabetic ketoacidosis and nonketotic hyperglycemia were treated on a low-dose insulin protocol using intravenous infusion of insulin with the established rate of 0.1U·kg(-1)·h(-1). The patients received intravenous fluids and nutrition orally and intravenously. The levels of serum ICAM-1, E-selectin, and 8-iso-prostaglandin F(2α) (8-iso-PGF(2α)); the activities of superoxide dismutase (SOD); the total antioxidant capacity (TAC) and the contents of malondialdehyde (MDA) in 68 patients with hyperglycemia crisis on admission and after insulin therapy with resolution of hyperglycemia and ketoacidosis (72 h after resolution) were measured. Another 33 healthy individuals served as normal controls.

RESULTS

The activities of SOD and TAC at admission were lower in patients with hyperglycemia crisis than in normal controls, and the levels of MDA, 8-iso-PGF(2α), ICAM-1 and E-selectin were higher in patients with hyperglycemia crisis than in normal controls (all p<0.05). The activities of SOD and TAC in patients at resolution were significantly lower than in patients at admission and were significantly higher than in controls (p<0.05). The levels of MDA, 8-iso-PGF(2α), ICAM-1 and E-selectin in patients at resolution were markedly lower than in patients at admission (all p<0.05) and were significantly higher than in normal controls (p<0.05). There was a significant positive correlation between ICAM-1 and SOD (r=0.32, p<0.05) and between E-selectin and MDA (r=0.30, p<0.05) in patients at admission, and the level of E-selectin was positively correlated with MDA and 8-iso-PGF(2α) in patients at resolution (r=0.33, 0.36, p<0.05). In stepwise regression analysis, MDA and 8-iso-PGF(2α) showed a significant association with E-selectin, and 8-iso-PGF(2α) showed a significant association with ICAM-1.

CONCLUSION

The oxidative stress and the levels of serum circulating adhesion molecules are significantly changed in patients with hyperglycemia crisis. Intensive insulin therapy can attenuate the abnormity of oxidative stress and the levels of serum circulating adhesion molecules in patients with hyperglycemia crisis.

Endocrine and metabolic emergencies: hypoglycaemia

Hypoglycaemia is rare in healthy individuals owing to the numerous elegant hormonal and neuronal mechanisms that maintain glucose homeostasis. Glucose is an obligate metabolic fuel for cerebral tissue and therefore hypoglycaemia, if uncorrected, can have disastrous consequences including death. Clinical hypoglycaemia is defined as a plasma (or serum) glucose concentration low enough to cause symptoms and/or signs, including impairment of brain function. However, no single plasma (or serum) glucose concentration categorically defines hypoglycaemia. Hypoglycaemia is probably the most common endocrine and metabolic emergency in clinical practice. The overwhelming majority of occurrences of hypoglycaemia occur in patients with diabetes, either as a result of treatment-induced hypoglycaemia and/or abnormalities that affect the normal counterregulatory response to hypoglycaemia. The differential for nondiabetes-associated hypoglycaemia is broad and includes insulinoma, drugs, hormone deficiencies, and critical illness. The acute management of hypoglycaemia is discussed along with a review of the pathophysiology and aetiology of this commonly encountered clinical problem.

Glucose management in the neurosurgical patient: are we yet any closer?

PURPOSE OF REVIEW

This review focuses on recent findings in perioperative management of blood glucose control using intensive insulin therapy in neurosurgical and neurocritical care and in other intensive care unit patients. We also aim to address practical issues and make recommendations that may contribute to the safe clinical application of intensive insulin therapy targeted to optimize blood glucose control in these patients.

RECENT FINDINGS

Intensive insulin therapy targeted to obtain tight blood glucose control induces a substantial increase in the number of hypoglycemic episodes and mortality rate. On the contrary, hyperglycemia--both isolated episodes and high mean glucose levels--is associated with worsened neurologic outcome and increased mortality.

SUMMARY

In neurosurgical and neurocritical care as well as other intensive care unit patients, both hypoglycemia and hyperglycemia have significant adverse effects. The optimal glucose level remains under debate but significant steps have evolved with the call for judicious control and elimination of the historical approach to glycemic management, which underestimated drawbacks associated with dysglycemia. The increased incidence of hypoglycemia and mortality as well as the impact of hyperglycemia on worsening neurologic function in patients with acute brain damage heightens the need for more clinical studies on perioperative glucose management in these patients.