Prenatal diagnosis and clinical implications of an apparently isolated right aortic arch.

OBJECTIVE: To define the associations of a prenatally diagnosed, apparently isolated right aortic arch (RAA) with chromosomal or genetic abnormalities and tracheal compression. METHODS: This was a retrospective study of apparently isolated RAA assessed by fetal cardiologists and fetal medicine specialists at Kings College Hospital, London between 2000 and 2017. RESULTS: The search identified 138 cases of apparently isolated RAA. Invasive testing was performed in 75, and chromosomal or genetic anomalies were identified in 16 (22%), and the most common was 22q11 microdeletion. An aberrant left subclavian artery was seen in 51% of cases. Symptoms of a vascular ring were present in 24 of 97 (25%) children who were reviewed after birth. Bronchoscopy was performed in 33 children, and significant tracheal compression was diagnosed in 28, including 18 of 19 symptomatic and 10 of 14 asymptomatic children. CONCLUSIONS: An apparently isolated RAA is associated with a high incidence of chromosomal or genetic abnormalities and a high incidence of tracheal compression in symptomatic and asymptomatic patients. Prenatal counselling for genetic associations and postnatal airway assessment in the context of the vascular anatomy is recommended.

Correlation of Symptoms with Bronchoscopic Findings in Children with a Prenatal Diagnosis of a Right Aortic Arch and Left Arterial Duct.

A right aortic arch (RAA) with a left arterial duct (LAD) together encircle the trachea and have the potential to cause tracheobronchial compression and published guidelines recommend bronchoscopy in symptomatic patients. The aim of the study was to describe the incidence of tracheal compression in a cohort of prenatally diagnosed RAA and LAD. Retrospective review of clinical course and imaging of prenatal cases of RAA and LAD assessed with flexible bronchoscopy over an 11-year period. 34 cases of prenatally diagnosed RAA with LAD underwent bronchoscopy at median age of 9 months (range 0.4-123) of whom 11 had respiratory symptoms and 23 were asymptomatic. In the neonatal period, three cases demonstrated respiratory symptoms. An aberrant left subclavian artery (ALSA) was identified in 29 cases. Pulsatile tracheal compression was identified in 32/34 (94%) cases and two cases showed normal tracheal appearances. Significant tracheal compression (> 70% occlusion) was present in 25/34 (74%) cases of which 16 were asymptomatic. Significant carinal compression (> 70% occlusion) was identified in 14/34 (42%) cases, an ALSA was observed in 13/14. Surgical relief of a vascular ring has been performed in 27 (79%) cases at a median age of 15 months (range 0.6-128 months). At surgery, a fibrous remnant of an atretic left aortic arch was identified in 11/27 (41%) cases. Significant tracheal compression may be present in infants even without symptoms. If early relief of airway compression is to be achieved to promote normal development of tracheal cartilage, early bronchoscopy should be considered.

Case-based discussion from the neonatal intensive care unit: a case of an intentional oesophageal intubation.

Tracheal agenesis (TA) is a rare congenital defect consisting of complete or partial absence of the trachea below the larynx. Antenatal diagnosis is challenging, and most cases are detected in the postnatal period. Airway management of such cases, particularly in the absence of antenatal diagnosis, can be challenging. Various methods of management have been described but with limited success, and overall prognosis remains very poor. We present an unexpected case of TA, highlighting management issues and diagnostic methods.

Stenting the atrial septum: a hybrid approach guided solely by echocardiography.

Stenting the atrial septum to achieve decompression of the atrium is well described and commonly performed via a percutaneous catheter approach under combined fluoroscopic and echocardiographic guidance. We describe two successful cases of a hybrid approach to atrial stenting under echocardiographic guidance alone, as a viable alternative approach.

Relationship between arterial partial oxygen pressure after resuscitation from cardiac arrest and mortality in children.

BACKGROUND: Observational studies in adults have shown a worse outcome associated with hyperoxia after resuscitation from cardiac arrest. Extrapolating from adult data, current pediatric resuscitation guidelines recommend avoiding hyperoxia. We investigated the relationship between arterial partial oxygen pressure and survival in patients admitted to the pediatric intensive care unit (PICU) after cardiac arrest. METHODS AND RESULTS: We conducted a retrospective cohort study using the Pediatric Intensive Care Audit Network (PICANet) database between 2003 and 2010 (n=122,521). Patients aged <16 years with documented cardiac arrest preceding PICU admission and arterial blood gas analysis taken within 1 hour of PICU admission were included. The primary outcome measure was death within the PICU. The relationship between postarrest oxygen status and outcome was modeled with logistic regression, with nonlinearities explored via multivariable fractional polynomials. Covariates included age, sex, ethnicity, congenital heart disease, out-of-hospital arrest, year, Pediatric Index of Mortality-2 (PIM2) mortality risk, and organ supportive therapies. Of 1875 patients, 735 (39%) died in PICU. Based on the first arterial gas, 207 patients (11%) had hyperoxia (Pa(O)(2) ≥300 mm Hg) and 448 (24%) had hypoxia (Pa(O)(2) <60 mm Hg). We found a significant nonlinear relationship between Pa(O)(2) and PICU mortality. After covariate adjustment, risk of death increased sharply with increasing hypoxia (odds ratio, 1.92; 95% confidence interval, 1.80-2.21 at Pa(O)(2) of 23 mm Hg). There was also an association with increasing hyperoxia, although not as dramatic as that for hypoxia (odds ratio, 1.25; 95% confidence interval, 1.17-1.37 at 600 mm Hg). We observed an increasing mortality risk with advancing age, which was more pronounced in the presence of congenital heart disease. CONCLUSIONS: Both severe hypoxia and, to a lesser extent, hyperoxia are associated with an increased risk of death after PICU admission after cardiac arrest.

Pulmonary artery sling: An overview.

Pulmonary artery sling is a rare childhood vascular tracheobronchial compression syndrome that is frequently associated with tracheal stenosis. Consequently, neonates or infants may present with critical airway obstruction if there is long segment airway narrowing and complete rings. Rapid diagnosis of this cardiac vascular malformation and evaluation of the extent and severity of airway involvement is essential to plan surgery, typically a slide tracheoplasty to relieve critical airway obstruction. Long term outcome can be excellent following surgical repair of the stenosed airway and reimplantation of the left pulmonary artery. In this review we focus on the embryology, diagnostic workup, airway investigations and management for this rare but challenging congenital condition.

Single-center review on safety of biodegradable airway stenting in pediatric population.

BACKGROUND: Tracheobronchomalacia (TBM) and airway stenosis are recognized etiologies of airway obstruction among children. Their management is often challenging, requiring multiple interventions and prolonged respiratory support with associated long-term morbidity. Metallic or silicone stents have been used with mixed success and high complication rates. More recently biodegradable Ella stents (BES) provided an attractive interventional option. OBJECTIVES: We report our experience in the treatment of TBM and vascular airway compression using BES. We deliberately downsized them to minimize intraluminal granulation tissue formation. MATERIALS AND METHODS: Retrospective study over an 8-year period between November 2012 and December 2020 of pediatric patients with severe airway obstruction requiring airway stenting for extubation failure, malacic death spells, recurrent chest infections, or lung collapse. RESULTS: Thirty-three patients (5 tracheal and 28 bronchial diseases) required 55 BES during the study period. The smallest patient weighed 1.8 kg. Median age of patient at first stent implantation was 13.1 months (IQR 4.9-58.3). The majority of the bronchial stents were in the left main bronchus (93%), of which 57% for vascular compression. Repeat stents were used in 19 patients (57.7%), with a range of two to four times. We did not experience erosion, infection, or obstructive granuloma needing removal by forceps or lasering. Three stent grid occluded with secretions needing bronchoscopic lavage. Stent migration occurred in three patients. CONCLUSIONS: BES holds promise as a treatment option with low rate of adverse effects for a specific subset of pediatric patients with airway malacia or vascular compression. Further studies are warranted.

Long term outcome of babies with pulmonary hypertension.

Neonatal pulmonary hypertension (PH) is associated with many severe congenital abnormalities (congenital diaphragmatic hernia) or acquired cardiorespiratory diseases such as pneumonia, meconium aspiration and bronchopulmonary dysplasia (BPD). If no cause is found it may be labelled idiopathic persistent pulmonary hypertension of the newborn. Although PH may result in life threatening hypoxia and circulatory failure, in the majority of cases, it resolves in the neonatal period following treatment of the underlying cause. However, in some cases, neonatal PH progresses into infancy and childhood where symptoms include failure to thrive and eventually right heart failure or death if left untreated. This chronic condition is termed pulmonary vascular hypertensive disease (PHVD). Although classification and diagnostic criteria have only recently been proposed for pediatric PHVD, little is known about the pathophysiology of chronic neonatal PH, or why pulmonary vascular resistance may remain elevated well beyond infancy. This review explores the many factors involved in chronic PH and what implications this may have on long term outcome when the disease progresses beyond the neonatal period.

The relationship among thromboelastography, hemostatic variables, and bleeding after cardiopulmonary bypass surgery in children.

BACKGROUND: Mediastinal bleeding is common after pediatric cardiopulmonary bypass (CPB) surgery. Thromboelastography (TEG) may predict bleeding and provide insight into likely mechanisms. We aimed to (a) compare perioperative temporal profiles of TEG and laboratory hemostatic variables between patients with significant hemorrhage (BLEED) and those without (CONTROL), (b) investigate the relationship between TEG variables and routine hemostatic variables, and (c) develop a model for prediction of bleeding. METHODS: TEG and laboratory hemostatic variables were measured prospectively at 8 predefined times for 50 children weighing <20 kg undergoing CPB. RESULTS: Patients who bled demonstrated different TEG profiles than those who did not. This was most apparent after protamine administration and was partly attributable to inadequate heparin reversal, but was also associated with a significantly lower nadir in mean (sd) fibrinogen for the BLEED group compared with CONTROL group: 0.44 (0.18) and 0.71 (0.40) g/L, respectively (P = 0.01). Significant nonlinear relationships were found between the majority of TEG and laboratory hemostatic variables. The strongest relationship was between the maximal amplitude and the platelet-fibrinogen product (logarithmic r(2) = 0.71). Clot strength decreased rapidly when (a) fibrinogen concentration was <1 g/L, (b) platelets were <120 x 10(9)/L, and (c) platelet-fibrinogen product was <100. A 2-variable model including the activated partial thromboplastin time at induction of anesthesia and TEG mean amplitude postprotamine discriminated well for subsequent bleeding (C statistic 0.859). CONCLUSIONS: Hypofibrinogenemia and inadequate heparin reversal are 2 important factors contributing to clot strength and perioperative hemorrhage after pediatric CPB. TEG may be a useful tool for predicting and guiding early treatment of mediastinal bleeding in this group.

Extended-interval gentamicin: population pharmacokinetics in pediatric critical illness.

OBJECTIVES: Once-daily gentamicin therapy is becoming increasingly common in pediatric practice; however, little is known about pharmacokinetics in critical illness. Gentamicin exhibits concentration dependant killing; thus, peak serum concentrations at least eight times higher than minimum inhibition concentration of the target organism have been recommended. We wanted to derive pharmacokinetic parameters for gentamicin in critical illness and to evaluate whether a dose of 8 mg/kg provides an adequate peak serum concentration (>16 mg/L). PATIENTS AND INTERVENTIONS: Population-based pharmacokinetic analyses were undertaken using therapeutic drug monitoring data collected prospectively in an intensive care unit over 6 months (n = 50 children). Monte Carlo simulations were used to estimate the probability of achieving 1) peak concentrations >16 mg/L; and 2) trough concentrations <2 mg/L at 24 and 36 hrs. MEASUREMENTS AND MAIN RESULTS: The optimal pharmacokinetic model was of two-compartment disposition with zero order input and additive residual error. Weight was associated nonlinearly with clearance and linearly with volume, and age was a significant covariate for clearance. An 8-mg/kg dose provided near 100% probability of achieving adequate peak concentrations at all ages. However this probability decreased rapidly at doses <7 mg/kg with neonates being the most susceptible. Approximately 50% of nonpremature neonates within the first week of life, 25% of infants, and 10% of children are likely to need a dose interval >24 hrs. CONCLUSIONS: A gentamicin dose of 8 mg/kg is highly likely to achieve peak concentrations >16 mg/L in critically ill children. A considerable proportion will require dose intervals >24 hrs; thus, therapeutic drug monitoring is essential.

Biodegradable Stents for the Relief of Vascular Bronchial Compression in Children With Left Atrial Enlargement.

BACKGROUND: We report our experience of the biodegradable polydioxanone stent in cases of bronchial compression by a dilated left atrium in children with heart disease. METHODS: Eight custom-made biodegradable stents were inserted into the left main bronchus in 5 patients diagnosed with critical airway compression. Four of the 5 patients were ventilator-dependent with significant cardiac morbidity. RESULTS: Stents were inserted without complication under fluoroscopic guidance. All experienced improvement in symptoms over time. In 3 patients, repeat bronchial stenting was performed where stent degradation was associated with recurrence of vascular airway compression and symptoms. No stents migrated nor was there evidence of bronchial or vascular erosion. There was 1 death, unrelated to the stent, and all remaining survivors were well at a 2-year follow-up. CONCLUSION: The use of the polydioxanone biodegradable stent appeared safe in this cohort of critically ill patients with vascular bronchial compression. There use may aid weaning from mechanical ventilation and support eventual cardiac recovery.

Cor pulmonale due to congenital central hypoventilation syndrome presenting in adolescence.

OBJECTIVE: To report the first case of congenital central hypoventilation syndrome (CCHS) presenting with severe cor pulmonale in an adolescent. METHODS AND DESIGN: Case report and literature review. Our Institutional Review Board waived the need for consent. SETTING: Pediatric intensive care unit in a tertiary care children's hospital. PATIENT: A 12-year-old girl who developed profound hypoxia following routine dental extraction under intravenous opiate sedation and became progressively obtunded due to marked hypoventilation without hypoxic arousal, requiring mechanical ventilation. She had evidence of severe right heart failure, but no cardiac, pulmonary, neurologic, or neuromuscular cause was identified. The diagnosis of CCHS was suspected and subsequently confirmed by blood polymerase chain reaction analysis that revealed a heterozygous polyalanine expansion mutation of the PHOX2B gene (five polyalanine repeats). CONCLUSIONS: This report describes the unusual presentation of severe cor pulmonale in an adolescent with so-called "late-onset" CCHS. CCHS was previously thought to be a disease affecting only neonates, but the late-onset phenotype has now been well described in adults. It should be considered in any child presenting with unexplained right heart failure without an identifiable cause, particularly if central sleep apnea is present, because early initiation of ventilatory support can prevent cardiac and neurologic sequelae and improve outcome.

Application of the Boston Technical Performance Score to intraoperative echocardiography.

BACKGROUND: The Technical Performance Score (TPS) developed by Boston Children's Hospital showed surgical outcomes correlate with adequacy of technical repair when implemented on pre-discharge echocardiograms. We applied this scoring system to intraoperative imaging in a tertiary UK congenital heart surgical centre. METHODS: After a period of training, intraoperative TPS (epicardial and/or transesophageal echocardiography) was instituted. TPS was used to inform intraoperative discussions and recorded on a custom-made database using the previously published scoring system. After a year, we reviewed the feasibility, results and relationship between the TPS and mortality, extubation time and length of stay. RESULTS: From 01 September 2015 to 04 July 2016, there were 272 TPS procedures in 251 operations with 208 TPS recorded. Seven patients had surgery with no documented TPS, three had operations with no current TPS score template available. Patients left the operating theatre with TPS optimal in 156 (75%), adequate 34 (16%) and inadequate 18 (9%). Of those with an optimal score on leaving theatre, ten had more than one period of cardiopulmonary bypass. All four deaths <30 days after surgery (1.9%) had optimal TPS. There was a statistically significant difference in extubation times in the RACHS category 4 patients (3 days vs 5 days, P < 0.05) and in PICU and total length of stay in the RACHS category three patients (2 and 8 days vs 12.5 and 21.5 days respectively) if leaving theatre with an inadequate result. CONCLUSIONS: Application of intraoperative TPS is feasible and provides a way of objectively recording intraoperative imaging assessment of surgery. An 'inadequate' TPS did not predict mortality but correlated with a longer ventilation time and longer length of stay compared to those with optimal or adequate scores.

Critical airway obstruction in apparently asymptomatic neonates.

Central airway obstruction (trachea and major bronchi) in neonates can be caused by malacia, stenosis, or compression by masses or vascular structures. These abnormalities may be present in the neonatal period but are typically not detected until at least 6 months of age. We present four patients (1.6-4.1 kg, 32-41 weeks gestation) with nonspecific symptoms (e.g., poor weight gain, difficulty weaning from CPAP) who underwent bronchoscopy in the neonatal period. Critical airway obstruction (>90%) was identified in these relatively asymptomatic neonates. We suggest a low threshold for investigation with bronchoscopy in high-risk neonates. Pediatr Pulmonol. 2017;52:E15-E17. © 2016 Wiley Periodicals, Inc.

Safe implementation of standard concentration infusions in paediatric intensive care.

OBJECTIVE: To evaluate safety, following introduction of standard concentrations of morphine infusions in paediatric critical care. METHODS: Implementation: A multidisciplinary team was convened, and several workstreams designated, including derivation of concentrations, manufacturing, supply, prescribing, administration using smart pump technology, training and evaluation. Safety Evaluation: Retrieval of all existing data on medication errors linked to morphine use using our hospital incident reporting system and risk assessment of errors in relation to standard concentration implementation. KEY FINDINGS: The pilot identified several areas for improvement, stock control, reasons for reverting from standard to variable concentrations and sources of error. Improvements included the following: refining morphine concentrations and weight limits for bands, pump reprogramming and education. Long-term Safety: Over an 8-year period, 126 morphine-related incidents occurred (two-thirds in the 3 years around introduction). Of note, 67% (85/126) resulted in no patient harm; the remainder 33% resulted in low harm. Analysis of administration errors revealed that up to 70% could be eliminated by refining technology to include bar coding. These included the following: wrong syringe selection (24%), wrong pump mode (28%) and wrong patient weight inputted (18%). CONCLUSION: Introduction of standard infusions is safe and effective. We are exploring ways to further refine safety and extending to other drugs.

Retrospective evaluation of a paediatric intensivist-led flexible bronchoscopy service.

OBJECTIVE: To demonstrate the diagnostic yield, therapeutic role and safety of flexible bronchoscopy via an intensivist-led service in critically ill children. DESIGN: Retrospective chart review. SETTING: Regional paediatric intensive care unit. MEASUREMENTS AND RESULTS: One hundred forty-eight flexible bronchoscopies were performed by two intensivists on 134 patients (median age 16.5 months) over a 2.5-year period. Eighty-eight percent of patients required mechanical ventilation, and 22% were receiving inotropes. Case mix included general (n = 77), cardiac surgery (n = 18), cardiology (n = 13), ear-nose-and-throat surgery (n = 17), oncology (n = 8) and renal (n = 1). The indication for bronchoscopy was defined a priori according to one of four categories: suspected upper airway disease (n = 32); lower airway disease (n = 70); investigation of pulmonary disease (n = 25); and extubation failure (n = 21). Bronchoscopy was generally performed soon after PICU admission, at a median time of 1.5 days for the former three categories, and 4 days for extubation failure group. A positive yield from bronchoscopy (diagnosis that explained the clinical condition or influenced patient management) was present in 113 of 148 (76%) procedures, varying within groups from 44% (pulmonary disease) to 90% (extubation failure). Ten percent of patients developed a fall in oxygen saturations > 20% during the procedure and 17% required a bolus of at least 10 ml/kg of 0.9% saline for hypotension. CONCLUSIONS: Critically ill patients with respiratory problems may benefit from a PICU-led bronchoscopy service as the yield for positive bronchoscopic finding is high, particularly for upper airway problems or extubation failure.

The influence of hyperchloraemia on acid base interpretation in diabetic ketoacidosis.

OBJECTIVES: During the acute treatment of diabetic ketoacidosis we (a) determined the temporal incidence of hyperchloraemia, and (b) quantified the influence of hyperchloraemia on interpretation of common blood gas derived acid base parameters, namely base deficit and bicarbonate. DESIGN AND SETTING: Retrospective chart review in two regional paediatric intensive care units. MEASUREMENTS AND RESULTS: Stewart's physicochemical theory was used to develop regression equations quantifying the acidifying effect of hyperchloraemia on both base deficit and bicarbonate. These were then applied retrospectively to blood chemistry results from 18 children (median age 12.7 years, weight 43 kg) with diabetic ketoacidosis. Plasma ketonaemia was estimated using the albumin-corrected anion gap. The incidence of hyperchloraemia, as documented by a ratio of plasma chloride to sodium of greater than 0.79, increased from 6% at admission to 94% after 20 h of treatment. Correction for chloride produced a dramatic improvement in the relationship between changes in the anion gap vs. both base deficit (from R(2)=0.55 to R(2)=0.95) and bicarbonate (from R(2)=0.51 to R(2)=0.96) during treatment. After 20 h of treatment the mean base deficit had decreased from 24.7 mmol/l to 10.0 mmol/l however, the proportion that was due to hyperchloraemia increased from 2% to 98%. CONCLUSIONS: It is now possible using a simple correction factor to quantify the confounding effect of hyperchloraemia on both base deficit and bicarbonate in diabetic ketoacidosis. This bedside tool may be a useful adjunct to guide therapeutic interventions.