Childhood interstitial lung diseases in immunocompetent children in Australia and New Zealand: a decade's experience

BACKGROUND

Childhood interstitial lung disease (chILD) represents a rare heterogeneous group of respiratory disorders. In the absence of randomized controlled clinical trials, global collaborations have utilized case series with an aim to standardising approaches to diagnosis and management. Australasian data are lacking. The aim of this study was to calculate prevalence and report the experience of chILD in Australasia over a decade.

METHODS

Paediatric pulmonologists in Australia and New Zealand involved in the care of patients aged 0-18 years with chILD completed a questionnaire on demographics, clinical features and outcomes, over a 10 year period. These data, together with data from the 2 reference genetics laboratories, were used to calculate prevalence.

RESULTS

One hundred fifteen cases were identified equating to a period prevalence (range) of 1.5 (0.8-2.1) cases/million for children aged 0-18years. Clinical data were provided on 106 patients: the <2 year group comprised 66 children, median age (range) 0.50 years (0.01-1.92); the ≥2 year group comprised 40 children, median age 8.2 years (2.0-18.0). Management approach was heterogeneous. Overall, 79% of patients had a good clinical outcome. Mortality rate was 7% in the study population.

CONCLUSION

chILD is rare in Australasia. This study demonstrates variation in the investigations and management of chILD cases across Australasia, however the general outcome is favorable. Further international collaboration will help finesse the understanding of these disorders.

Determination of hprt mutant and mutation frequencies and the molecular characterization of human derived in vivo T-lymphocyte mutants

Using a T-lymphocyte clonal assay, 73 6-thioguanine resistant T-lymphocytes were isolated from two blood samples obtained 4 months apart from a 50-year-old male subject. Sixty-six of these mutants were characterized at the DNA sequence level using cDNA. One particular single base substitution was recovered a total of 23 times. The majority of T-cell receptors (TCR) of these mutants all share a common gamma-TCR rearrangement, and thus likely represent a single mutational event that underwent clonal expansion in vivo. Siblings of this clone were recovered in both collections. Three other single base substitutions were also recovered more than once. In two of the three cases, the mutants were also found to be clonally related, while in one case they were not. A number of identical exon loss events were also recovered, yet none of these were clonally related. This probably reflects the multiple pathways by which these mutations can arise. The TCR data was used to correct the observed mutant frequency to produce an estimate of the actual mutation frequency. The two mutant frequencies, 18 x 10(-6) and 19 x 10(-6), obtained from the first and second sampling periods, respectively, can thus be corrected to yield true mutation frequency's of 12 x 10(-6) each.

Nasal mask average volume-assured pressure support in an infant with congenital central hypoventilation syndrome

Congenital central hypoventilation syndrome (CCHS) is a rare disorder characterized by alveolar hypoventilation and autonomic dysregulation secondary to mutations of the PHOX 2B genes. Treatment consists of assisted ventilation using positive pressure ventilators via tracheostomy, bi-level positive airway pressure (BPAP), negative pressure ventilators, or diaphragm pacing. Previous case reports have highlighted early use of nasal non-invasive BPAP use in infants with CCHS. We present a case of a 10-month-old infant who was successfully managed on a new feature of non-invasive ventilation called average volume assured pressure support (AVAPS) without the need for tracheostomy. The AVAPS feature enables the machine to automatically adjust the inspiratory pressures to deliver a constant targeted tidal volume. This feature enabled a better control of ventilation as indicated by a more stable transcutaneous carbon dioxide profile compared to conventional nasal non-invasive BPAP, making non-invasive ventilation a more accessible method of managing sleep hypoventilation in CCHS.

Unusual Presentation of Severe Endobronchial Obstruction Caused by Cryptococcus gattii in a Child

Disease caused by Cryptococcus gattii typically manifests as meningoencephalitis or pulmonary nodules. Endobronchial lesions are rare, and most cases are caused by Cryptococcus neoformans. We describe here a case of endobronchial disease in a child caused by C gattii. The disease spectrum in this patient was notable for the discovery of anti-granulocyte macrophage colony-stimulating factor autoantibodies.

Radiation risk estimation in human populations: lessons from the radiological accident in Brazil

The development of radiological and nuclear technologies and the deployment of nuclear weapons have made ionizing radiation one of the most studied human mutagens. Exposure to ionizing radiation produces DNA damage which can result in mutation and cancer, making the risk associated with human exposure a critical issue. In this paper we estimate the risk associated with radiation exposure for individuals exposed to 137Cs during the 1987 Goiânia radiological accident. Using combined regression slopes from both the in vivo hprt mutant frequency and micronucleus frequency data we estimated a doubling dose of 173 (+/-47) cGy for these two endpoints. This is in close agreement with the published estimates for low dose rate and chronic exposure to low-LET radiation. We obtained risk estimates of about 24-fold increase in dominant disorders in the post-exposure generation of the directly exposed population. No detectable increase was found in the population at large. The risk of carcinogenesis in the directly exposed population was found to be increased by a factor in the range of 1.4 to 1.5. The small sample size in this study requires a large element of caution with respect to risk estimates interpretation. Moreover, the doubling dose estimates prepared here are derived from lymphocytes. This somatic data may require additional considerations for both cancer and certainly germ-line events. Nevertheless, the risk of carcinogenesis and genetic harm for this population are good indicators of the potential genetic damage imposed by ionizing radiation to the Goiânia population.

Variation in Gentamicin Dosing and Monitoring in Pediatric Units across New South Wales

INTRODUCTION

Gentamicin is an aminoglycoside antibiotic with broad-spectrum bactericidal activity and is widely used in pediatric units to treat infection with susceptible organisms. This study aimed to describe the dosage regimen for gentamicin and approach to its therapeutic drug monitoring (TDM) among the pediatric units within the state of New South Wales (NSW).

METHODS

A questionnaire was sent electronically to representatives of 40 pediatric units in NSW, requesting details of each unit's gentamicin dosing and TDM policy.

RESULTS

A total of 35 units responded to the survey. The majority (63%) of the units used a dose of 7.5 mg/kg of gentamicin in patients with normal renal function. More than half of the units (54%) did not have a local gentamicin dosing protocol and relied on other sources for dosing regimens. Dosing responses varied from a dose of 6 mg/kg once daily for patients more than 10 years of age to 7 mg/kg once daily on day 1, followed by 5 mg/kg once daily for patients over 10 years of age. For TDM of gentamicin, 63% of units indicated use of trough levels and 23% units used the Hartford Nomogram.

CONCLUSIONS

A significant variation exists in clinical practice among pediatric units in NSW on gentamicin dosing and TDM guidelines. There is an urgent need for collaboration among nursing, medical, and pharmacy experts to achieve consensus to develop and adopt statewide uniform guidelines on gentamicin dosing and TDM.

Increased hprt mutant frequencies in Brazilian children accidentally exposed to ionizing radiation

We have examined the effects of ionizing radiation on somatic mutations in vivo, using the hprt clonal assay. The study was performed on blood samples obtained from children exposed during a radiological accident that happened in 1987, in Goiânia, Brazil. The group of children exposed to ionizing radiation includes six males and four females ranging in age from 6 to 14 years at the time of exposure. The radiation doses ranged from 15 to 70 cGy. A Brazilian control group, not exposed to ionizing radiation, was also analyzed under similar conditions. the mean hprt mutant frequency for the exposed group was 4.6 times higher than the control group, although the cloning efficiency from the exposed group was significantly reduced. Linear regression analysis of the mutant frequency and ionizing radiation dose did not show a significant relationship between these two parameters. However, a reliable inverse relationship was demonstrated when the regression analysis was performed with nonselective cloning efficiency and ionizing radiation dose. It was demonstrated that nonselective cloning efficiency diminishes as ionizing radiation dose increases. To correct mutant frequencies for clonal events, the clonal relationship between the hprt mutant clones was examined by T-cell receptor analysis. The majority of the mutants analyzed represented individual clones, thus validating the observed mutant frequencies.

Propranolol's effects on the sleep of infants with hemangiomas: A prospective pilot study

OBJECTIVE

To assess propranolol's impact on sleep when used in infants and toddlers with infantile hemangioma (80% under 6 months old).

METHODS

Parents and caregivers of infants and toddlers with infantile hemangioma presenting to a tertiary pediatric hospital's dermatology clinic and assessed by their dermatologist as requiring propranolol treatment were invited to participate. All participants completed an extended version of the Brief Infant Sleep Questionnaire (BISQ) prior to propranolol treatment initiation, which acted as the control, and 5 weeks after treatment commencement. Objective data were gathered through actigraphy, which utilizes a small wristwatch-like device that measures sleep-wake patterns, for 1 week prior to initiation and again 5 weeks after commencement. BISQ responses and actigraphy values from the two time points were compared.

RESULTS

55 infants and toddlers (aged 0-2.8 years, 80% under 6 months) were included. Sleep was reported as only a minor problem by most parents 5 weeks after starting propranolol (P = .049). Subgroup analysis of 45 infants <6 months old showed no significant difference in sleep while taking propranolol. Whole cohort BISQ data analysis showed a statistically significant increase in night-time sleep (P = .024), and a decrease in the number (P = .003) and duration of daytime naps (P = .025) following commencement of propranolol. Actigraphy data completed in 10 infants showed no significant difference in sleep quality before and 5 weeks after commencing propranolol.

CONCLUSION

Propranolol did not significantly impair sleep quality and pattern in our cohort of infants and toddlers with infantile hemangioma. Most parents considered the impact on sleep to be only a minor problem.

Disease caused by non-tuberculous mycobacteria in children with cystic fibrosis

Non-tuberculous mycobacterial (NTM) (especially M. abscessus complex) infections pose a considerable challenge in the management of lung disease in patients with cystic fibrosis (CF). The apparent increase in prevalence is likely multifactorial. Emergent evidence of patient-to-patient transmission and isolation of highly resistant strains is a concern for all CF centers around the world. Treatment is often long and burdensome with multiple agents. Treatment side effects are frequent and can cause significant morbidity. Although consensus guidelines provide some direction, many units are faced with the challenges of: finding drug combinations for highly resistant strains; dealing with interruptions of treatment; discussing additional facilitating procedures in the form of gastrostomy and long-term vascular access devices; as well as supporting families emotionally and psychologically through the process.

Average volume-assured pressure support vs conventional bilevel pressure support in pediatric nocturnal hypoventilation: a case series

STUDY OBJECTIVES

Average volume-assured pressure support (AVAPS) is a modality of noninvasive ventilation that provides a targeted tidal volume by automatically adjusting the inspiratory pressure support within a set range. Pediatric studies evaluating the efficacy of AVAPS in treating nocturnal hypoventilation are confined to case reports. The aim of this study was to compare AVAPS to conventional bilevel positive airway pressure (BPAP) support in improving hypercarbia in a cohort of pediatric patients with nocturnal hypoventilation.

METHODS

Retrospective review of patient records at an established tertiary pediatric sleep laboratory over a 6-year period. Ventilatory and sleep study parameters from AVAPS and conventional BPAP titration studies were compared. AVAPS was used only if hypoventilation was not controlled using conventional BPAP. Inspiratory pressures, tidal volumes, and adherence were downloaded on final titrated ventilatory settings. Comparisons were made using paired t test.

RESULTS

A total of 19 patients (11 boys, 8 girls; median age 10.5 years, range 1 to 20 years) were identified. Diagnoses included neuromuscular disease (n = 9), obstructive hypoventilation (n = 5), parenchymal lung disease (n = 4), and congenital central hypoventilation syndrome (n = 2). AVAPS demonstrated significant improvement in peak (P = .009) and mean (P = .001). Transcutaneous CO₂ parameters compared to conventional bilevel. Oxygenation on AVAPS showed positive trend but did not reach statistical significance. AVAPS delivered higher tidal volumes (P = .04) using similar pressures. There was no statistically significant difference in obstructive apnea-hypopnea index, respiratory arousal index, sleep efficiency, and adherence between AVAPS and conventional BPAP.

CONCLUSIONS

AVAPS was an effective alternative to conventional BPAP in improving hypercarbia in our selective cohort of pediatric patients. Prospective, longitudinal studies are needed to evaluate the benefits of AVAPS feature in the pediatric population.

Clinical Outcomes of Single vs. Two-Strain Probiotic Prophylaxis for Prevention of Necrotizing Enterocolitis in Preterm Infants

Background: The administration of live microbiota (probiotic) via enteral route to preterm infants facilitates intestinal colonization with beneficial bacteria, resulting in competitive inhibition of the growth of pathogenic bacteria preventing gut microbiome dysbiosis. This dysbiosis is linked to the pathogenesis of necrotizing enterocolitis (NEC), an acquired multi-factorial intestinal disease characterized by microbial invasion of the gut mucosa, particularly affecting preterm infants. Probiotic prophylaxis reduces NEC; however, variations in strain-specific probiotic effects, differences in administration protocols, and synergistic interactions with the use of combination strains have all led to challenges in selecting the optimal probiotic for clinical use. Aim: To compare any differences in NEC rates, feeding outcomes, co-morbidities in preterm infants receiving single or two-strain probiotics over a 4-year period. The two-strain probiotic prophylaxis was sequentially switched over after 2 years to the single strain probiotic within this 4-year study period, in similar cohort of preterm infants. Methods: During two consecutive equal 2-year epochs, preterm infants (<32 weeks and or with birth weight <1,500 g) receiving two-strain (Lactobacillus acidophilus and Bifidobacterium bifidum) and single strain (Bifidobacterium breve M-16 V,) probiotic prophylaxis for prevention of NEC were included in this retrospective, observational study. The primary outcome included rates of NEC; secondary outcomes included prematurity related co-morbidities and feeding outcomes. Time to reach full enteral feeds was identified as the first day of introducing milk feeds at 150 ml/kg/day. Results: There were 180 preterm infants in the two-strain, 196 in the single strain group from the two equal consecutive 2-year epochs. There were no differences in the NEC rates, feeding outcomes, all-cause morbidities except for differences in rates of retinopathy of prematurity. Conclusion: In our intensive-care setting, clinical outcomes of single vs. two-strain probiotic prophylaxis for prevention of NEC were similar. Although our study demonstrates single strain probiotic may be equally effective than two-strain in the prevention of NEC, small sample size and low baseline incidence of NEC in our unit were not sufficiently powered to compare single vs. two-strain probiotic prophylaxis in preventing NEC. Further clustered randomized controlled trials are required to study the effects of single vs. multi-strain probiotic products for NEC prevention in preterm infants.

Non-invasive home ventilation using the average volume assured pressure support feature in an infant with severe bronchopulmonary dysplasia and chronic respiratory failure

Introduction

While majority of infants with bronchopulmonary dysplasia (BPD) can be discharged home without low flow oxygen or on supplemental low flow oxygen, some require long term home mechanical ventilation.

Case presentation

We present a case of an extremely premature infant with severe bronchopulmonary dysplasia who was successfully managed at home on a new feature of non-invasive ventilation called average volume assured pressure support (AVAPS) without the need for tracheostomy. The AVAPS feature enables the machine to deliver a consistent tidal volume by automatically adjusting the inspiratory pressure within a set range.

Conclusion

The use of AVAPS feature in our case improved ventilation as indicated by a more stable gas exchange profile, making home non-invasive ventilation a more practicable method of managing severe BPD in this infant.

Pediatric Average Volume Assured Pressure Support

Average volume assured pressure support (AVAPS) is a modality of non-invasive ventilation that enables the machine to deliver a pre-set tidal volume by adjusting the inspiratory pressure support within a set range. Data on its use in the pediatric population are limited to case reports and single centre case series. This article reviews paediatric data on use of AVAPS and highlights the need for validation to help develop specific guidelines on use of AVAPS in children.

An infrequent cause of neonatal upper airway obstruction: Congenital nasal pyriform aperture stenosis presenting to a remote facility

INTRODUCTION

Congenital nasal pyriform aperture stenosis (CNPAS) is a rare congenital condition of structural nasal obstruction. Respiratory distress, stertor, and poor feeding are often presenting features.

CASE PRESENTATION

We report a case of a newborn diagnosed with CNPAS at 3 weeks of life. The diagnosis was missed on a nasoendoscopy at day 3 of life but was realised following a facial CT when the infant presented with ongoing symptoms of upper airway obstruction. Nasal dilation was performed successfully.

CONCLUSION

CNPAS should be considered in any neonate with upper airway obstruction. A normal nasoendoscopy does not exclude the diagnosis.

Three generations of a family diagnosed with congenital central hypoventilation syndrome: A case series

Congenital central hypoventilation syndrome (CCHS) is an autosomal dominant disorder characterized by alveolar hypoventilation and autonomic dysregulation secondary to mutations of the PHOX2B genes. We present five cases from three generations within the same family with varying degrees of phenotypic expression of the PHOX2B gene mutation. The cases were diagnosed following identification of CCHS in index case at birth. This case series underscores the importance of screening first-degree relatives of individuals with confirmed CCHS and alerts the clinicians to maintain a high degree of suspicion in asymptomatic family members given the high degree of phenotypic variability of CCHS.

Delivery of average assured pressure support (AVAPS) through tracheostomy in paediatric patients

Average volume-assured pressure support (AVAPS) mode has been available since 2009 and allows the ventilator to deliver a constant pre-set tidal volume by automatically adjusting the inspiratory pressures within a set range. Data in AVAPS mode use is limited in both paediatric populations, and in patients who are ventilated through a tracheostomy. This case series reports on the successful use of AVAPS mode in four paediatric patients with tracheostomy ventilation.