The effect of cardiopulmonary bypass on the hypothalamic-pituitary-adrenal axis in children

Critical Illness-Related Corticosteroid Insufficiency (CIRCI) After Pediatric Cardiac Surgery

Although current studies do not support the routine use of corticosteroids after cardiopulmonary bypass in pediatric patients, there is incomplete understanding of the potential hemodynamic contribution of postoperative critical illness-related corticosteroid insufficiency in the intensive care unit. By reviewing the available studies and underlying pathophysiology of these phenomena in critically ill neonates, we can identify a subset of patients that may benefit from optimal diagnosis and treatment of receiving postoperative steroids. A suggested algorithm used at our institution is provided as a guideline for treatment of this high-risk population.

Steroid Use for Management of Vasoactive Resistant Shock in Pediatric Cardiac Intensive Care Patients: Experience of the Consortium of Congenital Cardiac Care-Measurement of Nursing Practice

BACKGROUND

Although a variety of doses and duration of hydrocortisone have been reported as a treatment modality for congenital heart surgery patients with refractory hypotension, there remains a lack of understanding of the clinical use in pediatric cardiac programs.

OBJECTIVES

The aim of this study was to describe the current practice of steroid use for refractory hypotension in postoperative congenital heart surgery patients.

METHOD

Survey participants were recruited from the Consortium of Congenital Cardiac Care-Measurement of Nursing Practice. The survey focused on 4 areas: diagnosis, intervention, duration of therapy, and clinical decision making. Data were summarized using descriptive statistics.

RESULTS

Among the programs, 24 of 31 (77%) responded, with 21 (95%) using hydrocortisone as a treatment modality. Most, 20 (83%), reported no written clinical guideline for the use of hydrocortisone. Variation in dosing existed as 3 centers (14%) use 50 mg/m2/d, 6 (29%) use 100 mg/m2/d, and 8 (38%) indicated that dosing varies by provider.

DISCUSSION

Nearly all centers reported using hydrocortisone for the treatment of hypotension refractory to fluid resuscitation and vasoactive medications. Substantial variation in practice exists in areas of diagnosis, dosing, and duration of hydrocortisone. More research is needed to develop a clinical practice guideline to standardize practice.

Patterns and Determinants of Change in Cortisol Levels and Thyroid Function as a Function of Cardiac Risk in Children Undergoing Cardiac Surgery

Background

Children undergoing cardiac surgery with cardiopulmonary bypass (CPB) are exposed to the risk of hormonal imbalances resulting from acute stress, which may eventually result in high postoperative mortality and morbidity.

Objective

We assessed adrenal and thyroid hormonal changes and their determinants following cardiac surgery in children and explored their prognostic value in predicting cardiac outcomes. Study Design and Methods. A prospective cohort study was conducted at King Abdulaziz University Hospital (KAUH), between 2017 and 2018. The study involved 46 children aged 14 years or younger who underwent elective cardiac surgery with cardiopulmonary bypass. Serum levels of cortisol, TSH, fT3, and fT4 were measured preoperatively and 24, 48, and 72 hours after surgery. The cardiac risk was assessed using the risk adjustment for congenital heart surgery (RACHS) scale. A composite cardiovascular outcome was analyzed as a numerical variable and calculated as the number of cardiovascular events.

Results

Overall, the changes in thyroid function parameters resulted in a U-shaped curve, while cortisol levels yielded a bell-shaped curve. The most significant changes occurred at 24 hours postop, including a decrease in mean TSH by 2.08 μIU/L (p < 0.001), fT3 by 2.39 pmol/L (p < 0.001), and fT4 by 2.45 pmol/L (p < 0.001) and an increase in cortisol levels by 406.48 nmol/L (p < 0.001) with respect to the baseline. Cortisol concentration peaked higher and recovered slower among patients with high cardiac risk than their counterparts. Cardiovascular outcomes were independently predicted by the extent of the decline in fT4 and TSH at 48 and 72 hours postop, with reference to the baseline, and by the cortisol level at 24 h postop, independent of the baseline, besides the RACHS category.

Conclusion

Cardiac surgery among children yields a high adrenocortical response and a high incidence of nonthyroidal illness syndrome, increasing cardiovascular risk. A preventive management strategy involves improving surgical techniques to minimize trauma-related stress.

Effects of dexmedetomidine on stress hormones in patients undergoing cardiac valve replacement: a randomized controlled trial

Background

Stress response always occurs in cardiac valve replacement patients undergoing cardiopulmonary bypass (CPB).

Methods

60 patients undergoing cardiac valve replacement were recruited and randomized into control and Dex groups. Dex group received 1.0 μg·kg-1 of Dex for 10 min intravenously before anesthesia, followed by 0.5 μg·kg-1·h-1 of Dex, steadily administered throughout the procedure. And controlled group received the identical velocity of saline as Dex group. Plasma level of cortisol (Cor), epinephrine (E), norepinephrine (NE), and serotonin (5-HT) were evaluated at four timepoints: Before administration (T0), sawn sternum (T1), end of extracorporeal circulation (T2), and 24 h post operation (T3). General data of operation and recovery such as heart rate (HR), mean arterial pressure (MAP), intraoperative bispectral index (BIS), and hospitalization time in the intensive care unit (ICU) were also compared.

Results

Increase of Cor, E, NE, and 5-HT for the Dex group was significant lesser than that in the control group (P < 0.05), and ICU hospitalization time and ventilator support time was significantly shorter in the Dex group. The proportion of patients discharged from the hospital with better prognosis was significantly higher than that in the control group, while there were no significant differences in hospitalization costs and vasoactive drugs use between the two groups.

Conclusions

Dex reduces plasma Cor, E and NE elevations in patients after CPB, alleviates the stress reaction of the body, shortens the hospitalization time and ventilator support time in ICU, and plays a positive role in the rehabilitation of patients undergoing cardiac valve replacement.

Trial registration

China Clinical Trial Registry (No. ChiCTR-IPR-17010954) March 22rd, 2017.

Adrenal insufficiency in neonates undergoing cardiopulmonary bypass and postoperative hypothalamic-pituitary-adrenal function after prophylactic glucocorticoids

OBJECTIVES

Determine incidence of preoperative adrenal insufficiency in neonates >35 weeks gestation with congenital heart disease undergoing cardiothoracic surgery with bypass and effects of prophylactic methylprednisolone on postoperative hypothalamic-pituitary-adrenal function and hemodynamic stability.

DESIGN

Prospective observational study in 36 neonates with preoperative adrenocorticotrophic hormone stimulation tests and serial total cortisol and adrenocorticotrophic hormone measurements before and after surgery. Data analyses: analysis of variance and regression.

RESULTS

Baseline circulating adrenocorticotrophic hormone and cortisol were unchanged 4-20 days postnatal (P > 0.1); however, cortisol levels rose with increasing adrenocorticotrophic hormone, P = 0.02. Ten neonates (29%) demonstrated preoperative adrenal insufficiency (∆cortisol ≤9 µg/dl); one had postoperative hemodynamic instability. Growth-restricted neonates had lower baseline cortisol, but normal stimulation tests and responded well to surgical stresses. Seventy-five percent of neonates receiving perioperative methylprednisolone demonstrated postoperative hypothalamic-pituitary-adrenal inhibition.

CONCLUSION

Adrenal insufficiency appears common in neonates >35 weeks gestation with congenital heart disease, but did not contribute to postoperative hemodynamic instability despite hypothalamic-pituitary-adrenal inhibition.

Comprehensive Management Considerations of Select Noncardiac Organ Systems in the Cardiac Intensive Care Unit

As the acuity and complexity of pediatric patients with congenital cardiac disease have increased, there are many noncardiac issues that may be present in these patients. These noncardiac problems may affect clinical outcomes in the cardiac intensive care unit and must be recognized and managed. The Pediatric Cardiac Intensive Care Society sought to provide an expert review of some of the most common challenges of the respiratory, gastrointestinal, hematological, renal, and endocrine systems in pediatric cardiac patients. This review provides a brief overview of literature available and common practices.

Steroids in paediatric heart surgery: eminence or evidence-based practice?

Steroids in paediatric heart surgery are given prophylactically to blunt the systemic inflammatory response induced by the extracorporeal circuit and to improve clinical outcomes. However, there is an ongoing controversy about the impact of steroids on clinical outcomes after paediatric heart surgery. The hypothalamic-pituitary-adrenal axis is the primary neuroendocrine system activated during the stress of surgery. Relative adrenal insufficiency can accompany paediatric heart surgery; therefore, perioperative steroid supplementation is still administered by some centres. The studies that investigate the hypothalamic-pituitary-adrenal axis physiology during surgery have many limitations, and it is unclear how to define what is adrenal insufficiency. In this review, we focus on discussing the available evidence for steroid use in paediatric cardiac surgery.

Cardiopulmonary Resuscitation in Infants and Children With Cardiac Disease: A Scientific Statement From the American Heart Association

Cardiac arrest occurs at a higher rate in children with heart disease than in healthy children. Pediatric basic life support and advanced life support guidelines focus on delivering high-quality resuscitation in children with normal hearts. The complexity and variability in pediatric heart disease pose unique challenges during resuscitation. A writing group appointed by the American Heart Association reviewed the literature addressing resuscitation in children with heart disease. MEDLINE and Google Scholar databases were searched from 1966 to 2015, cross-referencing pediatric heart disease with pertinent resuscitation search terms. The American College of Cardiology/American Heart Association classification of recommendations and levels of evidence for practice guidelines were used. The recommendations in this statement concur with the critical components of the 2015 American Heart Association pediatric basic life support and pediatric advanced life support guidelines and are meant to serve as a resuscitation supplement. This statement is meant for caregivers of children with heart disease in the prehospital and in-hospital settings. Understanding the anatomy and physiology of the high-risk pediatric cardiac population will promote early recognition and treatment of decompensation to prevent cardiac arrest, increase survival from cardiac arrest by providing high-quality resuscitations, and improve outcomes with postresuscitation care.

Corticosteroids in Pediatric Heart Surgery: Myth or Reality

Background: Corticosteroids have been administered prophylactically for more than 60 years in pediatric heart surgery, however, their use remains a matter of debate. There are three main indications for corticosteroid use in pediatric heart surgery with the use of cardiopulmonary bypass (CPB): (1) to blunt the systemic inflammatory response (SIRS) induced by the extracorporeal circuit; (2) to provide perioperative supplementation for presumed relative adrenal insufficiency; (3) for the presumed neuroprotective effect during deep hypothermic circulatory arrest operations. This review discusses the current evidence behind the use of corticosteroids in these three overlapping areas. Materials and Methods: We conducted a structured research of the literature using PubMed and MEDLINE databases to November 2017 and additional articles were identified by cross-referencing. Results: The evidence suggests that there is no correlation between the effect of corticosteroids on inflammation and their effect on clinical outcome. Due to the limitations of the available evidence, it remains unclear if corticosteroids have an impact on early post-operative outcomes or if there are any long-term effects. There is a limited understanding of the hypothalamic-pituitary-adrenal axis function during cardiac surgery in children. The neuroprotective effect of corticosteroids during deep hypothermic circulatory arrest surgery is controversial. Conclusions: The utility of steroid administration for pediatric heart surgery with the use of CPB remains a matter of debate. The effect on early and late outcomes requires clarification with a large multicenter randomized trial. More research into the understanding of the adrenal response to surgery in children and the effect of corticosteroids on brain injury is warranted.

An International Survey of Corticosteroid Use for the Management of Low Cardiac Output Syndrome

OBJECTIVE

Limited evidence exists on use of corticosteroids in low cardiac output syndrome following cardiac surgery. We sought to determine physicians' practices and beliefs with regard to corticosteroids therapy for low cardiac output syndrome.

DESIGN

Multinational internet-based survey.

SETTING

Pediatric Cardiac Intensive Care Society member database.

SUBJECTS

Pediatric cardiac intensive care physicians.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We received 188 responses from 85 centers throughout the world including 57 U.S. congenital heart centers, eight Canadian centers, and 20 international centers. The majority of respondents (51%) reported performing at least 200 bypass cases per year and had separate dedicated cardiac ICUs (57%). Most physicians (89%) rarely or never prescribe corticosteroids for mild low cardiac output syndrome (single vasoactive agent and mildly decreased perfusion), whereas 94% of those surveyed sometimes or always administer corticosteroids to patients with severe low cardiac output syndrome (two or more vasoactive agents and persistent hypotension). Hydrocortisone was the most commonly used corticosteroids (88%), but there was no consensus on dosage used. There was a variable approach to cortisol level measurement and cortisol stimulation testing to inform therapy with corticosteroids. A majority of respondents (75%) stated that they would be willing to randomize patients with severe low cardiac output syndrome into a trial of corticosteroids efficacy.

CONCLUSIONS

Our survey demonstrates considerable practice variability with regard to the type of patients in whom corticosteroids are administered, adrenal axis testing is performed, and dosage of hydrocortisone used. The majority of physicians, however, stated their willingness to randomize patients with severe low cardiac output syndrome in a corticosteroids trial. This survey identified multiple areas for future research on use of corticosteroids for low cardiac output syndrome.

Salivary cortisol and cortisone in the clinical setting

PURPOSE OF REVIEW

A resurgence of interest in salivary biomarkers has generated evidence for their value in assessing adrenal function. The advantages of salivary measurements include only free hormone is detected, samples can be collected during normal daily routines and stress-induced cortisol release is less likely to occur than during venepuncture. We review the use of salivary biomarkers to diagnose and monitor patients for conditions of cortisol excess and deficiency and discuss the value of measuring salivary cortisone versus salivary cortisol.

RECENT FINDINGS

Developments in laboratory techniques have enabled the measurement of salivary hormones with a high level of sensitivity and specificity. In states of altered cortisol binding, salivary biomarkers are more accurate measures of adrenal reserve than serum cortisol. Salivary cortisone is a superior marker of serum cortisol compared with salivary cortisol, specifically when serum cortisol is low and during hydrocortisone therapy when contamination of saliva may result in misleading salivary cortisol concentrations.

SUMMARY

Salivary cortisol and cortisone can be used to assess cortisol excess, deficiency and hydrocortisone replacement, with salivary cortisone having the advantage of detection when serum cortisol levels are low and there is no interference from oral hydrocortisone.

Clinical significance of serum cortisol levels following surgery for congenital heart disease

OBJECTIVE

Use of hydrocortisone to treat refractory haemodynamic instability in patients recovering from surgery for congenital heart disease is common practice at many centres. We aimed to determine whether there is a relationship between total serum cortisol concentrations and haemodynamic response to this therapy. Material and methods We retrospectively reviewed patients <21 years who underwent cardiac surgery from 2011 to 2013, received hydrocortisone within 72 hours postoperatively, and had total serum cortisol measurements contemporaneous with its administration. Favourable responders were defined as patients in whom, at 24 hours after hydrocortisone initiation, either (1) systolic blood pressure was increased or unchanged and vasoactive-inotrope score was decreased or (2) systolic blood pressure increased by ⩾10% of baseline and vasoactive-inotrope score was unchanged. Variables were compared using t-tests or Mann-Whitney U tests as appropriate.

RESULTS

In total, 24 patients were reviewed, with a median age of 1.4 months and range of 0.1-232 months. Among them, 14 (58%) patients responded favourably to hydrocortisone. At 24 hours, the median change in vasoactive-inotrope score was -18% in favourable responders and +31% in those who did not respond favourably, p=0.001. The mean pre-hydrocortisone total serum cortisol in favourable responders was 17.4±10.9 µg/dl compared with 46.1±44.7 µg/dl in those who did not respond favourably, p=0.03.

CONCLUSION

Total serum cortisol obtained before initiation of hydrocortisone was significantly lower in patients who responded favourably to this therapy. Total serum cortisol may therefore be helpful in identifying children recovering from cardiac surgery who may or may not haemodynamically improve with hydrocortisone.

Adrenal insufficiency in neonates after cardiac surgery with cardiopulmonary bypass

BACKGROUND

Cardiopulmonary bypass (CPB) may lead to adrenal insufficiency (AI). Emerging evidence supports association of AI with morbidity after cardiac surgery.

AIMS

The aim of this study was to define AI incidence in neonates undergoing complex cardiac surgery with CPB and its association with intraoperative post-CPB outcomes.

METHODS

Forty subjects enrolled in a prior randomized control trial who received preoperative methylprednisolone as part of our institutional neonatal bypass protocol were included. No intraoperative steroids were given. ACTH stimulation tests were performed: preoperatively and 1 h after separation from CPB. AI was defined as <9 μg·ml^-1 increase in cortisol at 30 min post cosyntropin 1 mcg. Clinical outcomes were collected up to 90 min after CPB.

RESULTS

2/40 (5%) subjects had preoperative AI vs 13/40 (32.5%) post-CPB AI, P ≤ 0.001. No significant difference was observed in age, gestational age, weight, CPB time, circulatory arrest, or STAT category between subjects with or without post-CPB AI. ACTH decreased from preoperative values 127.3 vs 35 pcg·ml^-1 [median difference = 81.8, 95% CI = 22.7-127.3], while cortisol increased from 18.9 vs 75 μg·dl^-1 [median difference = 52.2, 95% CI = 36.3-70.9]. Post-CPB AI was associated with increased median colloid resuscitation, 275 vs 119 ml·kg^-1 [median difference = 97.8, 95% CI = 7.1-202.2]; higher median peak lactate, 9.4 vs 6.9 mg·dl^-1 [median difference = 3.2, 95% CI = 0.04-6.7]; median post-CPB lactate, 7.9 vs 4.3 mg·dl^-1 , [median difference 3.6, 95% CI = 2.1-4.7], and median lactate on admission to CICU, 9.4 vs 6.0 mg·dl^-1 [median difference = 3, 95% CI = 1.1-4.9]. No difference was observed in blood pressure or vasoactive inotrope score at any time point measured in operating room (OR). Higher initial post-CPB cortisol correlated with decreased cosyntropin response.

CONCLUSIONS

Neonatal cardiac surgery with CPB and preoperative methylprednisolone leads to AI as determined by low-dose ACTH stimulation test in one-third of patients. AI is associated with increased serum lactate and colloid resuscitation in OR. Impact of preoperative methylprednisolone on results is not defined. Benefit of postoperative steroid administration in neonates with post-CPB AI warrants further investigation.

Total and free cortisol responses and their relation to outcomes after cardiopulmonary bypass in infants

BACKGROUND

Hypothalamic-pituitary-adrenal (HPA) axis dysfunction may be partially responsible for the hemodynamic instability experienced by infants after cardiopulmonary bypass (CPB). We report the full spectrum of the HPA response surrounding CPB for infant congenital cardiac surgery.

METHODS

We enrolled 84 infants who received 1 mg/kg of dexamethasone before initiation of CPB. Total cortisol (TC), free cortisol (FC), adrenocorticotropic hormone (ACTH), and corticosteroid-binding globulin (CBG) were measured at 3 time points: immediately before CPB (TP1), on intensive care unit arrival (TP2), and at 24 hours after surgery (TP3). A 1-μg ACTH stimulation test was performed at each time point to evaluate adrenal responsiveness.

RESULTS

Sixty-eight infants completed all study procedures. Levels of TC, FC, CBG, and ACTH decreased significantly between the preoperative and 24-hour postoperative measurements. There were no significant associations between preoperative FC responses and clinical outcomes after adjusting for weight and Risk-Adjusted Scores for Congenital Heart Surgery. Infants with subnormal TC responses to ACTH stimulation (<9 μg/dL) at TP2 had greater fluid requirements (P < .001) and greater chest tube output (P < .001) during the first 24 hours, as well as longer length of stay (LOS) (P = .007). Except for LOS, these differences persisted for infants with subnormal stimulation tests at TP3.

CONCLUSIONS

We observed a significant decline in all aspects of the HPA axis throughout the first 24 hours after infant CPB. TC and FC levels were not associated with clinical outcomes. Subnormal (Δ <9 μg/dL) TC response to cosyntropin stimulation during the postoperative period was associated with increased fluid resuscitation and greater LOS.

Endocrinologic Diseases in Pediatric Cardiac Intensive Care

OBJECTIVES

The objectives of this review are to discuss the pathophysiology, clinical impact and treatment of hyperglycemia, and disturbances in thyroid and adrenal function prior to and following cardiac surgery in children.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSIONS

Disturbances in glucose metabolism and thyroid and adrenal function are common in critically ill children with cardiac disease and in particular in children undergoing cardiac surgery for complex congenital heart disease. An understanding of the pathophysiology, clinical impact and treatment of these disturbances is essential for the management of these at risk patients.

Steroids Improve Hemodynamics in Infants With Adrenal Insufficiency After Cardiac Surgery

OBJECTIVE

To investigate whether steroid replacement therapy improved hemodynamics in infants after surgery for congenital heart disease only when they develop adrenal insufficiency. The authors retrospectively investigated adrenal function and evaluated hemodynamic responses to steroid replacement therapy in infants after surgery for congenital heart disease.

DESIGN

Retrospective, cohort study.

SETTING

Intensive care unit in the National Cerebral and Cardiovascular Center Hospital in Japan.

PATIENTS

Thirty-two neonates and infants<3 months old who underwent cardiovascular surgery.

INTERVENTIONS

The patients were divided into 2 groups based on corticotropin stimulation test results: group AI with adrenal insufficiency (baseline cortisol<15 µg/dL or incremental increase after testing of<9 µg/dL, with baseline cortisol of 15-34 µg/dL); and group N with normal adrenal function. The corticotropin stimulation test was performed by injecting 3.5 µg/kg of tetracosactide acetate. Hydrocortisone (1 mg/kg) was administered every 6 hours, and hemodynamics were compared before and after steroid administration between the groups.

MEASUREMENTS AND MAIN RESULTS

Seven patients were classified into group AI, and demonstrated a mean blood pressure increase from 53±8 mmHg before treatment to 68±9 mmHg 18 hours after steroid administration (p<0.01). Urine output also increased, from 2.7±1.0 mL/kg/h to 4.8±1.9 mL/kg/h (p<0.05). In group N, neither mean blood pressure nor urine output increased after steroid administration.

CONCLUSIONS

After surgery for congenital heart disease, one-fifth of infants developed adrenal insufficiency. Steroid replacement therapy improved hemodynamics only in the subgroup with adrenal insufficiency.

Postoperative Hydrocortisone Infusion Reduces the Prevalence of Low Cardiac Output Syndrome After Neonatal Cardiopulmonary Bypass

OBJECTIVE

Neonatal cardiac surgery with cardiopulmonary bypass is often complicated by morbidity associated with inflammation and low cardiac output syndrome. Hydrocortisone "stress dosing" is reported to provide hemodynamic benefits in some patients with refractory shock. Development of cardiopulmonary bypass-induced adrenal insufficiency may provide further rationale for postoperative hydrocortisone administration. We sought to determine whether prophylactic, postoperative hydrocortisone infusion could decrease prevalence of low cardiac output syndrome after neonatal cardiac surgery with cardiopulmonary bypass.

DESIGN

Double-blind, randomized control trial.

SETTING

Pediatric cardiac ICU and operating room in tertiary care center.

PATIENTS

Forty neonates undergoing cardiac surgery with cardiopulmonary bypass were randomized (19 hydrocortisone and 21 placebo). Demographics and known risk factors were similar between groups.

INTERVENTIONS

After cardiopulmonary bypass separation, bolus hydrocortisone (50 mg/m²) or placebo was administered, followed by continuous hydrocortisone infusion (50 mg/m²/d) or placebo tapered over 5 days. Adrenocorticotropic hormone stimulation testing (1 μg) was performed before and after cardiopulmonary bypass, prior to steroid administration. Blood was collected for cytokine analysis before and after cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

Subjects receiving hydrocortisone were less likely to develop low cardiac output syndrome (5/19, 26% vs 12/21, 57%; p = 0.049). Hydrocortisone group had more negative net fluid balance at 48 hours (-114 vs -64 mL/kg; p = 0.01) and greater urine output at 0-24 hours (2.7 vs 1.2 mL/kg/hr; p = 0.03). Hydrocortisone group weaned off catecholamines and vasopressin sooner than placebo, with a difference in inotrope-free subjects apparent after 48 hours (p = 0.033). Five placebo subjects (24%) compared with no hydrocortisone subjects required rescue steroids (p = 0.02). Thirteen (32.5%) had adrenal insufficiency after cardiopulmonary bypass. Patients with adrenal insufficiency randomized to receive hydrocortisone had lower prevalence of low cardiac output syndrome compared with patients with adrenal insufficiency randomized to placebo (1/6 vs 6/7, respectively; p = 0.02). Hydrocortisone significantly reduced proinflammatory cytokines. Ventilator-free days, hospital length of stay, and kidney injury were similar.

CONCLUSIONS

Prophylactic, postoperative hydrocortisone reduces low cardiac output syndrome, improves fluid balance and urine output, and attenuates inflammation after neonatal cardiopulmonary bypass surgery. Further studies are necessary to show if these benefits lead to improvements in more important clinical outcomes.

Comparison of Adrenal Suppression between Etomidate and Dexmedetomidine in Children with Congenital Heart Disease

Background

The aim of this study was to compare plasma cortisol concentration during anesthesia of children with congenital heart disease who received dexmedetomidine (DEX) with those who received etomidate (ETO).

Material/Methods

We recruited 99 ASA physical status II–III pediatric patients scheduled for congenital heart disease (CHD) corrective surgery and divided into them into 3 groups. Group DEX received an infusion of DEX intravenously with a bolus dose of 0.5 μg·kg⁻¹ within 10 min during anesthesia induction, followed by a maintenance dose of DEX 0.5 μg·kg⁻¹·h⁻¹. Group ETO received ETO intravenously with a bolus dose of 0.3 mg·kg⁻¹ without a maintenance dose. Group CON received routine anesthetics as controls. The preset timepoints were: before anesthesia induction (T0), at the end of induction (T1), 30 min after anesthesia induction (T2), at the time of aortic and inferior vena catheterization (T3), and at 180 min (T4) and 24 h (T5) after anesthesia induction.

Results

The cortisol concentration decreased gradually after anesthesia induction in all groups, and returned to baseline values after 24 h. The cortisol concentration was significantly lower in Group ETO children than in Group DEX or group CON at T4.

Conclusions

The plasma concentrations of cortisol decreased in CHD children after the operation, but returned to baseline after 24 h of anesthesia induction. The adrenal cortex function inhibition induced by ETO in CHD children is longer and more serious than that induced by DEX (if any) during the preoperative period.

Dynamic pituitary-adrenal interactions in response to cardiac surgery

OBJECTIVES

To characterize the dynamics of the pituitary-adrenal interaction during the course of coronary artery bypass grafting both on and off pump. Since our data pointed to a major change in adrenal responsiveness to adrenocorticotropic hormone, we used a reverse translation approach to investigate the molecular mechanisms underlying this change in a rat model of critical illness.

DESIGN

CLINICAL STUDIES

Prospective observational study.

ANIMAL STUDIES

Controlled experimental study.

SETTING

CLINICAL STUDIES

Cardiac surgery operating rooms and critical care units.

ANIMAL STUDIES

University research laboratory.

SUBJECTS

CLINICAL STUDIES

Twenty, male patients.

ANIMAL STUDIES

Adult, male Sprague-Dawley rats.

INTERVENTIONS

CLINICAL STUDIES

Coronary artery bypass graft-both on and off pump.

ANIMAL STUDIES

Injection of either lipopolysaccharide or saline (controls) via a jugular vein cannula.

MEASUREMENTS AND MAIN RESULTS

CLINICAL STUDIES

Blood samples were taken for 24 hours from placement of the first venous access. Cortisol and adrenocorticotropic hormone were measured every 10 and 60 minutes, respectively, and corticosteroid-binding globulin was measured at the beginning and end of the 24-hour period and at the end of operation. There was an initial rise in both levels of adrenocorticotropic hormone and cortisol to supranormal values at around the end of surgery. Adrenocorticotropic hormone levels then returned toward preoperative values. Ultradian pulsatility of both adrenocorticotropic hormone and cortisol was maintained throughout the perioperative period in all individuals. The sensitivity of the adrenal gland to adrenocorticotropic hormone increased markedly at around 8 hours after surgery maintaining very high levels of cortisol in the face of "basal" levels of adrenocorticotropic hormone. This sensitivity began to return toward preoperative values at the end of the 24-hour sampling period.

ANIMAL STUDIES

Adult, male Sprague-Dawley rats were given either lipopolysaccharide or sterile saline via a jugular vein cannula. Hourly blood samples were subsequently collected for adrenocorticotropic hormone and corticosterone measurement. Rats were killed 6 hours after the injection, and the adrenal glands were collected for measurement of steroidogenic acute regulatory protein, steroidogenic factor 1, and dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1 messenger RNAs and protein using real-time quantitative polymerase chain reaction and Western immunoblotting, respectively. Adrenal levels of the adrenocorticotropic hormone receptor (melanocortin type 2 receptor) messenger RNA and its accessory protein (melanocortin type 2 receptor accessory protein) were also measured by real-time quantitative polymerase chain reaction. In response to lipopolysaccharide, rats showed a pattern of adrenocorticotropic hormone and corticosterone that was similar to patients undergoing coronary artery bypass grafting. We were also able to demonstrate increased intra-adrenal corticosterone levels and an increase in steroidogenic acute regulatory protein, steroidogenic factor 1, and melanocortin type 2 receptor accessory protein messenger RNAs and steroidogenic acute regulatory protein, and a reduction in dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1 and melanocortin type 2 receptor messenger RNAs, 6 hours after lipopolysaccharide injection.

CONCLUSIONS

Severe inflammatory stimuli activate the hypothalamic-pituitary-adrenal axis resulting in increased steroidogenic activity in the adrenal cortex and an elevation of cortisol levels in the blood. Following coronary artery bypass grafting, there is a massive increase in both adrenocorticotropic hormone and cortisol secretion. Despite a subsequent fall of adrenocorticotropic hormone to basal levels, cortisol remains elevated and coordinated adrenocorticotropic hormone-cortisol pulsatility is maintained. This suggested that there is an increase in adrenal sensitivity to adrenocorticotropic hormone, which we confirmed in our animal model of immune activation of the hypothalamic-pituitary-adrenal axis. Using this model, we were able to show that this increased adrenal sensitivity results from changes in the regulation of both stimulatory and inhibitory intra-adrenal signaling pathways. Increased understanding of the dynamics of normal hypothalamic-pituitary-adrenal responses to major surgery will provide us with a more rational approach to glucocorticoid therapy in critically ill patients.

Adrenal insufficiency in children undergoing heart surgery does not correlate with more complex postoperative course

Although some evidence suggests benefit of steroid supplementation after pediatric cardiac surgery, data correlating adrenal function with the postoperative course is scarce. This study sought to determine if adrenal insufficiency (AI) after cardiac surgery is associated with a more complicated postoperative course in children. A prospective study was performed during a 6-month period at a pediatric medical center. Included were 119 children, 3 months and older, who underwent heart surgery with cardiopulmonary bypass. Cortisol levels were measured before and 18 h after surgery. Patients were divided into two groups by procedure complexity (low or high), and clinical and laboratory parameters were compared between patients with and without AI within each complexity group. In the low-complexity group, 45 of the 65 patients had AI. The normal adrenal function (NAF) subgroup had greater inotropic support at 12, 24, and 36 h after surgery and a higher lactate level at 12 and 24 h after surgery. There were no significant differences between subgroups in duration of ventilation, sedation, intensive care unit (ICU) stay, or urine output. In the high-complexity group, 27 patients had AI, and 27 did not. There were no significant differences between subgroups in inotropic support or urine output during the first 36 h or in mechanical ventilation, sedation, or ICU stay duration. Children with AI after heart surgery do not have a more complex postoperative course than children with NAF. The adrenal response of individual patients seems to be appropriate for their cardiovascular status.

Anesthesia and the developing brain: relevance to the pediatric cardiac surgery

Anesthetic neurotoxicity has been a hot topic in anesthesia for the past decade. It is of special interest to pediatric anesthesiologists. A subgroup of children potentially at greater risk for anesthetic neurotoxicity, based on a prolonged anesthetic exposure early in development, are those children receiving anesthesia for surgical repair of congenital heart disease. These children have a known risk of neurologic deficit after cardiopulmonary bypass for surgical repair of congenital heart disease. Yet, the type of anesthesia used has not been considered as a potential etiology for their neurologic deficits. These children not only receive prolonged anesthetic exposure during surgical repair, but also receive repeated anesthetic exposures during a critical period of brain development. Their propensity to abnormal brain development, as a result of congenital heart disease, may modify their risk of anesthetic neurotoxicity. This review article provides an overview of anesthetic neurotoxicity from the perspective of a pediatric cardiac anesthesiologist and provides insight into basic science and clinical investigations as it relates to this unique group of children who have been studied over several decades for their risk of neurologic injury.

Dexamethasone levels predict cortisol response after infant cardiopulmonary bypass

OBJECTIVES

We sought to evaluate whether there is variability in blood dexamethasone levels after a standard 1 mg/kg dose of dexamethasone administered before infant cardiopulmonary bypass. We hypothesized that postoperative dexamethasone drug levels are highly variable, and that the infant stress response is related inversely to the amount of dexamethasone measured in the blood.

METHODS

Thirty-two infants (age, ≤365 days) received 1 mg/kg of dexamethasone before cardiopulmonary bypass (CPB) initiation. Blood was analyzed for cortisol, adrenocorticotropin, and interleukin (IL)-6, IL-8, and IL-10 levels after anesthesia induction, after CPB, after intensive care unit (ICU) arrival, and 4, 8, 12, and 24 hours after surgery. Patients were grouped as high dexamethasone (≥15 μg/dL) or low dexamethasone (<15 μg/dL) based on their level at ICU arrival.

RESULTS

Dexamethasone levels varied significantly between the high (n = 22) and low (n = 10) dexamethasone groups throughout the entire postoperative course and were correlated highly with cortisol response. Patients with high dexamethasone levels had postoperative cortisol levels that were lower than their pre-CPB baseline cortisol levels. Cortisol levels remained low throughout the first 24 postoperative hours even after dexamethasone levels neared zero. There were no significant differences between groups in the duration of mechanical ventilation or ICU length of stay.

CONCLUSIONS

Dexamethasone levels are highly variable at ICU arrival, despite standardized 1 mg/kg dosing before CPB initiation.

Postoperative serum cortisol concentration and adrenal insufficiency in neonates undergoing open-heart surgery

BACKGROUND

We sought to determine whether immediate postoperative serum cortisol concentration predicts adrenal insufficiency in neonates after cardiac surgery with cardiopulmonary bypass. We hypothesized that cortisol <10 µg/dL would be associated with increased catecholamine requirements and fluid resuscitation and would predict hemodynamic responsiveness to exogenous steroids.

METHODS

Retrospective study of 41 neonates was carried out for the levels of cortisol in the immediate postoperative period; of whom, 15 received steroids due to high levels of inotropic support. Laboratory and clinical outcomes were collected.

RESULTS

Median cortisol was 12 µg/dL (interquartile range: 5.2-27.4). Levels of cortisol <10 µg/dL was not associated with any clinical variable indicative of increased illness severity. Peak lactate (9.1 vs 11.8 mmol/L, P = .04) and maximum arteriovenous saturation difference ([Sao 2 - Svo 2] 28% vs 32%, P = .05) were both lower among patients with levels of cortisol <10 µg/dL. Six (40%) patients had a significant hemodynamic improvement within 24 hours after receiving steroids (responders), although there was no statistical difference between levels of cortisol in responders versus nonresponders. Level of cortisol was positively correlated with maximum lactate (P < .001), maximum Sao 2 - Svo 2 (P < .001), maximum inotrope score (P = .014), initial 24-hour fluid intake (P = .012), and time to negative fluid balance (P = .008) and was negatively correlated with initial 24-hour urine output (P < .001).

CONCLUSIONS

Low cortisol obtained in the immediate postoperative period is not associated with worse postoperative outcomes or predictive of steroid responsiveness. In contrast, elevated levels of cortisol are positively correlated with severity of illness. The use of an absolute cortisol threshold to identify adrenal insufficiency and/or guide steroid therapy in neonates after cardiac surgery is unjustified.

A survey of stated physician practices and beliefs on the use of steroids in pediatric fluid and/or vasoactive infusion-dependent shock

OBJECTIVE

Limited evidence exists on the use of corticosteroids in pediatric shock. We sought to determine physicians' practices and beliefs with regard to the management of pediatric shock.

DESIGN

Cross-sectional, Internet-based survey.

SETTING

Canada.

SUBJECTS

Physicians identified as practicing pediatric intensive care in any of 15 academic centers.

MEASUREMENTS AND MAIN RESULTS

Seventy of 97 physicians (72.2%) responded. Physicians stated that they were more likely to prescribe steroids for septic shock than for shock following cardiac surgery (odds ratio, 1.9 [95% CI, 0.9-4.3]) or trauma (odds ratio, 11.46 [95% CI, 2.5-51.2]), and 91.4% (64/70) would administer steroids to patients who had received 60 cc/kg of fluid and two or more vasoactive medications. Thirty-five percent of respondents (25/70) reported that they rarely or never conducted adrenal axis testing before giving steroids to patients in shock. Eighty-seven percent of respondents (61/70) stated that the role of steroids in the treatment of fluid and/or vasoactive drug-dependent shock needed to be clarified and that 84.3% would be willing to randomize patients into a trial of steroid efficacy who were fluid resuscitated and on one high-dose vasoactive medication. However, 74.3% stated that they would start open-label steroids in patients who required two high-dose vasoactive medications.

CONCLUSIONS

This survey provides information on the stated beliefs and practices of pediatric critical care physicians with regard to the use of steroids in fluid and/or vasoactive drug-dependent shock. Clinicians feel that the role of steroids in shock still requires clarification and that they would be willing to randomize patients into a trial. This survey may be useful as an initial framework for the development of a future trial on the use of steroids in pediatric shock.

Adrenocortical function in the postoperative pediatric cardiac surgical patient

PURPOSE OF REVIEW

Corticosteroids are frequently used in the postoperative care of children with congenital heart disease. This review describes the function of the adrenocortical axis in this population and the effects of corticosteroids on cardiovascular function. In addition, it examines the diagnosis of adrenal insufficiency in this population and provides an overview of recent studies on the use of steroids in treating hemodynamic instability in these children.

RECENT FINDINGS

Corticosteroids improve hemodynamic parameters in children with shock following congenital heart surgery. This improvement may be due to treatment of adrenal insufficiency or from direct cardiovascular effects of corticosteroids. The diagnosis of adrenal insufficiency in this population is challenging as low cortisol levels do not consistently correlate with adverse outcomes.

SUMMARY

Because of the lack of evidence delineating what the normal adrenocortical function is in this population, cortisol levels alone are not sufficient to justify treating with steroids in this population. Corticosteroids are beneficial in improving hemodynamics in children with shock after congenital heart surgery, but the adverse effects of the therapy in this context are not fully known. Prospective trials are necessary to clarify which patients may benefit from steroid therapy and to examine long-term effects of steroids.