Adrenal insufficiency in hemodynamically unstable neonates after open-heart surgery

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.

Results of a phase 1 multicentre investigation of dexmedetomidine bolus and infusion in corrective infant cardiac surgery

BACKGROUND

Dexmedetomidine (DEX) is increasingly used intraoperatively in infants undergoing cardiac surgery. This phase 1 multicentre study sought to: (i) determine the safety of DEX for cardiac surgery with cardiopulmonary bypass; (ii) determine the pharmacokinetics (PK) of DEX; (iii) create a PK model and dosing for steady-state DEX plasma levels; and (iv) validate the PK model and dosing.

METHODS

We included 122 neonates and infants (0-180 days) with D-transposition of the great arteries, ventricular septal defect, or tetralogy of Fallot. Dose escalation was used to generate NONMEM® PK modelling, and then validation was performed to achieve low (200-300 pg ml-1), medium (400-500 pg ml-1), and high (600-700 pg ml-1) DEX plasma concentrations.

RESULTS

Five of 122 subjects had adverse safety outcomes (4.1%; 95% confidence interval [CI], 1.8-9.2%). Two had junctional rhythm, two had second-/third-degree atrioventricular block, and one had hypotension. Clearance (CL) immediately postoperative and CL on CPB were reduced by approximately 50% and 95%, respectively, compared with pre-CPB CL. DEX clearance after CPB was 1240 ml min-1 70 kg-1. Age at 50% maximum clearance was approximately 2 days, and that at 90% maximum clearance was 18 days. Overall, 96.1% of measured DEX concentrations fell within the 5th-95th percentile prediction intervals in the PK model validation. Dosing strategies are recommended for steady-state DEX plasma levels ranging from 200 to 1000 pg ml-1.

CONCLUSIONS

When used with a careful dosing strategy, DEX results in low incidence and severity of adverse safety events in infants undergoing cardiac surgery with cardiopulmonary bypass. This validated PK model should assist clinicians in selecting appropriate dosing. The results of this phase 1 trial provide preliminary data for a phase 3 trial of DEX neuroprotection.

CLINICAL TRIALS REGISTRATION

NCT01915277.

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.

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.

Neonatal adrenal findings: significance and diagnostic approach. Description of two cases

Abnormal adrenal findings such as hemorrhage or calcifications in the neonate can stem from a variety of etiologies. Clinical presentation can vary significantly based on the degree of hemorrhage or the associated condition. Thorough work‐up is important to rule out critical underlying conditions as well as adrenal insufficiency.

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.

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.

Safety, efficacy and response to a hydrocortisone rescue therapy protocol in children with refractory hypotension after cardiopulmonal bypass

Little is known about which paediatric patients respond to hydrocortisone rescue therapy (HRT) with improvement of haemodynamic stability in refractory hypotension after cardiopulmonal bypass. Data were gathered retrospectively from children who received HRT in refractory hypotension after cardiopulmonary bypass in the period from 2000 to 2010. One hundred and sixty-six out of 1,273 children, 150 <1 year and 16 >1 year were enrolled. HRT improved haemodynamics significantly, increased blood pressure, decreased the vasoactive-inotropic score and plasma lactate concentrations in all children >1 year and in 82 % (123 out of 150) of the infants <1 year. Non-responders <1 year were significantly younger, lighter, mostly male infants and had longer cardiopulmonary bypass support time. Serum lactate and paediatric risk of mortality score were significantly higher in non-responders at time of initiation of HRT. Mortality was significantly higher in non-responders versus responders (2.44 vs. 13.5 %; p = 0.0008). HRT caused no adverse effects like electrolyte disturbances or hyperglycaemia. HRT in refractory hypotension after paediatric cardiac surgery is safe but not all infants <1 year show haemodynamic response to HRT. Non-response to HRT is associated with significantly higher mortality.

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.

Perioperative care of a child with transposition of the great arteries

OPINION STATEMENT

Because a minority of patients with D-transposition of the great arteries are diagnosed in utero by ultrasound, most present after delivery with cyanosis. In the absence of apparent lung disease, cyanotic neonates suspected of having a cardiac lesion should be immediately transferred to an intensive care unit at a pediatric tertiary care center for monitoring, resuscitation, and to define the cardiac anatomy and physiology. A prostaglandin E-1 infusion is usually initiated to maintain ductal patency and promote intra-cardiac mixing. In the past, balloon atrial septostomy (BAS) was routinely performed to enlarge the atrial septal defect and improve intra-cardiac mixing while the infants awaited surgery. Recent literature has reported an increase risk of stroke in neonates who undergo BAS, although more recent studies refute this. Our current practice is to perform BAS in neonates who have both echocardiographic evidence of a restrictive atrial septum and hypoxia or instability that is unresponsive to other interventions. The occasional patient who does not respond to initial management may have elevated pulmonary vascular resistance and may stabilize with pulmonary vasodilators, such as inhaled nitric oxide. Rarely, a child does not respond to interventional and pharmacologic resuscitation and requires mechanical support pre-operatively with extracorporeal membrane oxygenation (ECMO). In our experience, ECMO has been a successful bridge to corrective surgery with excellent outcomes. After pre-operative stabilization, arterial switch procedure is typically performed in the first week of life with very favorable early results.