Endocrine issues in the pediatric intensive care unit

The Effect of Various, Everyday Practices on Glucose Levels in Critically Ill Children

BACKGROUND

To evaluate the effect of various, everyday intensive care unit (ICU) practices on glucose levels in critically ill pediatric patients with the use of a continuous glucose monitoring system.

METHODS

Seventeen sensors were placed in 16 pediatric patients (8 male). All therapeutic and diagnostic interventions were recorded and 15 minutes later, a flash glucose measurement was obtained by swiping the sensor with a reader. Glucose difference was calculated as the glucose value 15 minutes after the intervention minus the mean daily glucose value for each individual patient. Additionally, the consciousness status of the patient (awake or sedated) was recorded.

RESULTS

Two hundred and five painful skin interventions were recorded. The mean difference of glucose values was higher by 1.84 ± 14.76 mg/dL (95% CI: -0.19 to 3.87 mg/dL, P = .076). However, when patients were categorized regarding their consciousness level, mean glucose difference was significantly higher in awake state than in sedated patients (4.76 ± 28.07 vs -2.21 ± 15.77 mg/dL, P < .001). Six hundred forty-nine interventions involving the respiratory system were recorded. Glucose difference during washings proved to be significantly higher than the ones during simple suctions (4.74 ± 14.18 mg/dL vs 0.32 ± 18.22 mg/dL, P = .016). Finally, glucose difference in awake patients was higher by 3.66 ± 13.91 mg/dL compared to glucose difference of -2.25 ± 21.07 mg/dL obtained during respiratory intervention in sedated patients.

CONCLUSIONS

Diagnostic and therapeutic procedures in the ICU, especially when performed in an awake state, exacerbate the stress and lead to a significant rise in glucose levels.

Management of the hospitalized patient with type 1 diabetes mellitus

Patients with type 1 diabetes mellitus (T1DM) have minimal to absent pancreatic β-cell function and rely on the exogenous delivery of insulin to obtain adequate and life-sustaining glucose homeostasis. Maintaining glycemic control is challenging in hospitalized patients with T1DM, as insulin requirements are influenced by the presence of acute medical or surgical conditions, as well as altered nutritional intake. The risks of hyperglycemia, ketoacidosis, hypoglycemia, and glycemic variability are increased in hospitalized patients with T1DM. Diabetic ketoacidosis and severe hypoglycemia are the 2 most common emergency conditions that account for the majority of hospital admissions in patients with T1DM. The association between hyperglycemia and increased risk of complications and mortality in patients with type 2 diabetes (T2DM) is well established; however, the impact of glycemic control on clinical outcomes has not been determined in patients with T1DM who present without ketoacidosis. To decrease complications associated with insulin therapy, health care professionals must be well versed in the use of insulin because it is a common source of medication error. For non-critically ill, hospitalized patients, subcutaneous insulin given to cover basal and prandial needs instead of sliding scale is the preferred method of insulin dosing. Protocols are available for initiating and titrating insulin doses, as well as for transitioning from an insulin infusion to a subcutaneous regimen. In our review, we identify and discuss special considerations related to inpatient glycemic control of non-ketotic patients with T1DM. Additionally, point differences and similarities associated with the management of patients with T2DM are discussed.

Stress response in critical illness

Sepsis brings about neuroendocrine dysfunction in children that differs significantly from that of adults and can thus be difficult to interpret and manage. Aggressive treatment of sepsis with appropriate and judicious use of antibiotics remains a top priority. Strict glycemic control in children has been associated with significant risk of hypoglycemia, which may independently contribute to morbidity and mortality. Timely initiation of hydrocortisone in persistently hypotensive children with fluid-refractory, catecholamine-resistant shock is controversial, but its use in children with suspected or proven adrenal insufficiency is suggested. Fluid and electrolyte abnormalities must be corrected. Treatment of thyroid dysfunction has been shown to be beneficial in certain specific populations but cannot be extrapolated to all septic patients with the current available data.

Thyroid function and stress hormones in children with stress hyperglycemia

The purpose of the study is to determine the prevalence of stress hyperglycemia and to investigate how thyroid and stress hormones alter during stress hyperglycemia in children admitted to pediatric emergency wards. A prospective cross-sectional study was conducted in children, less than 19 years old, who were admitted to pediatric emergency wards of Nemazee and Dastgheib Hospitals, Shiraz, Southern Iran. Those patients taking steroids, beta-agonists or intravenously administered glucose before venipuncture, and patients with diabetes mellitus (DM) or thyroid diseases were excluded. Children with blood glucose ≥ 150 mg/dL during admission were regarded as cases. The controls were age- and- sex- matched, euglycemic children. Stress hormones including cortisol, insulin, growth hormone, and prolactin were measured, and thyroid function was tested with a radioimmunoassay (RIA) method in all cases and controls. The results showed that among 1,054 screened children, 39 cases (3.7 %) had stress hyperglycemia and 89 controls were included in the study. The occurrence of hyperglycemia was independent of sex, but it occurred mostly in children under 6 years old. Hyperglycemia occurred more frequently in patients with a positive family history of DM (odds ratio = 3.2, 95 % CI = 1.3-7.9, and P = 0.009). There were no significant differences between cases and controls regarding any hormones except higher cortisol, and lower total T3 and T4 in cases compared with controls. Neither of cases developed diabetes in the 24-month follow-up period. These findings led us to the conclusion that stress hyperglycemia is occasionally seen in critically ill patients. Among the stress hormones measured, only cortisol increased during hyperglycemia. It seems that hyperglycemia is not an important risk factor for future diabetes.

Adrenal insufficiency in hemodynamically unstable neonates after open-heart surgery

OBJECTIVE

To investigate if the low dose (1 µg) ACTH stimulation test appropriately assesses adrenal responsiveness in neonates undergoing open-heart surgery requiring cardio-pulmonary bypass.

DESIGN

In this retrospective study, adrenal axis response was assessed on the first post-operative day with the low-dose (1 µg) ACTH stimulation test. Age, gender, weight, RACHS category, inotrope score, and baseline and post-stimulation cortisol levels were collected. The association between basal serum cortisol levels and degree of response to the ACTH stimulation test was also investigated.

SETTING

Tertiary care referral center.

PATIENTS

Twenty-one neonates who underwent neonatal cardiac surgery on cardiopulmonary bypass and underwent an ACTH stimulation test. Interventions.  Hydrocortisone 50 mg/m(2) bolus in four divided doses daily.

OUTCOME MEASURES

Response to the low dose (1 µg) ACTH stimulation was assessed.

RESULTS

All neonates with hemodynamic instability in the immediate post-operative period had low basal serum cortisol levels. The basal mean serum cortisol level for the 21 patients who underwent the low dose ACTH stimulation test was 7.3 µg/dL (median 2.2, range 0.7-42). The mean serum cortisol level increased after the ACTH stimulation test in the 21 patients to 39.6 µg/dL (median 38, range 79-17). The mean inotrope score in the first 24 hours after surgery was 24 (median 17.5, range 7-76.5) and decreased to 17 (median 14, range 5-52.3) 24-48 hours after surgery. At 48 hours post-surgery the mean arterial pressure in the groups with a serum cortisol increase after ACTH stimulation (<30 µg/dL vs. >50 µg/dL) was significantly different (P value 0.026).

CONCLUSIONS

The low dose (1 µg) ACTH stimulation test is a valid test to assess adrenal responsiveness among neonates after open heart surgery requiring CPB. Traditionally used basal serum cortisol level cutoff of <20 µg/dL used to define relative adrenal insufficiency may not be applicable in neonates undergoing open heart surgery on CPB thus indicating the need for re-defining adrenal insufficiency in this patient population.

Pediatric critical illness hyperglycemia: risk factors associated with development and severity of hyperglycemia in critically ill children

OBJECTIVE

To determine which children are susceptible to critical illness hyperglycemia (CIH) and whether CIH severity and duration correlate with diagnosis or illness severity.

STUDY DESIGN

We developed a standard approach to identify and treat CIH in our medical/surgical pediatric intensive care unit. We define CIH as persistent blood glucose (BG) >140 mg/dL and titrate infused insulin to maintain BG 80 to 140 mg/dL. We conducted a retrospective analysis of patients with hyperglycemia from June 2006 through May 2007. Main outcomes were risk of development of CIH in different patient subgroups and CIH severity and duration.

RESULTS

Average peak BG, CIH duration, and peak insulin requirements were 199 mg/dL, 6.3 days, and 0.09 units/kg/h, respectively, in patients with CIH. CIH severity and duration were highest in neurosurgical and patients with sepsis, those requiring mechanical ventilation and vasopressors, extracorporeal support, and those with highest illness severity scores.

CONCLUSIONS

CIH severity and duration correlate with diagnosis and illness severity. Certain "risk factors" may be predictive of who develops CIH.

Hyperglycaemia results from beta-cell dysfunction in critically ill children with respiratory and cardiovascular failure: a prospective observational study

Introduction

Hyperglycaemia is common in critical illness and associated with poor outcome. Glycaemic control using insulin may decrease morbidity and mortality. Many questions remain about the cause of critical illness hyperglycaemia (CIH). Our objective was to investigate the endocrinological basis of paediatric CIH.

Methods

C-peptide and blood glucose (BG) levels were assessed in 41 children aged 2 to 18 years old who were admitted to our paediatric intensive care unit (PICU). Patients who developed CIH, defined as persistent BG above 7.7 mmol/L, were treated with insulin infusion to achieve BG levels between 4.4 and 7.7 mmol/L. C-peptide levels were compared with respect to CIH development and degree of organ failure in all patients. Respiratory and cardiovascular failure were defined as need for mechanical ventilation and need for vasoactive infusions, respectively. Clinical and laboratory parameters, including c-peptide levels, were assessed.

Results

Of 41 children enrolled, 18 had respiratory failure only, 11 had both respiratory and cardiovascular failure, and 12 had neither respiratory or cardiovascular failure. Nine patients with respiratory failure only, 10 with both respiratory and cardiovascular failure, and none with no respiratory or cardiovascular failure developed CIH. Patients with CIH and respiratory and cardiovascular failure (n = 10) had very low c-peptide levels (4.4 ng/mL) despite significantly elevated mean BG levels (10.8 mmol/L), while those with CIH and respiratory failure only had very high c-peptide levels (11.5 ng/mL) with mean BG of 9.9 mmol/L. Low endogenous insulin production in those with respiratory and cardiovascular failure was associated with rapid onset of CIH, illness severity, higher insulin requirement and longer mechanical ventilation days, PICU length of stay and CIH duration.

Conclusions

Primary beta-cell dysfunction as defined by low endogenous c-peptide production appears to be prevalent in critically ill children with both respiratory and cardiovascular failure who develop CIH, whereas elevated insulin resistance appears to be the prominent cause of CIH in children with respiratory failure only. Our finding that beta-cell dysfunction is present in a subset of critically ill children with CIH challenges the assertion from adult studies that CIH is primarily the result of elevated insulin resistance.