Persisting hypoxaemia is an insufficient measure of adverse lung function in very immature infants

Noninvasive Respiratory Severity Indices Predict Adverse Outcomes in Bronchopulmonary Dysplasia

OBJECTIVE

To test the hypothesis that elevated respiratory severity indices will identify patients with severe bronchopulmonary dysplasia (BPD) at the greatest risk for adverse in-hospital outcomes.

STUDY DESIGN

This was a retrospective cohort study. A modified respiratory severity score (mean airway pressure × fraction of inspired oxygen) and a modified pulmonary score (respiratory support score × fraction of inspired oxygen + sum of medication scores) were calculated in a consecutive cohort of patients ≥36 weeks of postmenstrual age with severe BPD admitted to a referral center between 2010 and 2018. The association between each score and the primary composite outcome of death/prolonged length of stay (>75th percentile for cohort) was assessed using area under the receiver operator characteristic curve (AUROC) analysis and logistic regression. Death and the composite outcome death/tracheostomy were analyzed as secondary outcomes.

RESULTS

In 303 patients, elevated scores were significantly associated with increased adjusted odds of death/prolonged length of stay: aOR 1.5 (95% CI 1.3-1.7) for the modified respiratory severity score and aOR 11.5 (95% CI 5.5-24.1) for the modified pulmonary score. The modified pulmonary score had slightly better discrimination of death/prolonged length of stay when compared with the modified respiratory severity score, AUROC 0.90 (95% CI 0.85-0.94) vs 0.88 (95% CI 0.84-0.93), P = .03. AUROCs for death and death/tracheostomy did not differ significantly when comparing the modified respiratory severity score with the modified pulmonary score.

CONCLUSIONS

In our referral center, the modified respiratory severity score or the modified pulmonary score identified patients with established severe BPD at the greatest risk for death/prolonged length of stay, death, and death/tracheostomy.

Development of lung diffusion to adulthood following extremely preterm birth

Background

Gas exchange in extremely preterm (EP) infants must take place in fetal lungs. Childhood lung diffusing capacity of the lung for carbon monoxide (D_LCO) is reduced; however, longitudinal development has not been investigated. We describe the growth of D_LCO and its subcomponents to adulthood in EP compared with term-born subjects.

Methods

Two area-based cohorts born at gestational age ≤28 weeks or birthweight ≤1000 g in 1982–1985 (n=48) and 1991–1992 (n=35) were examined twice, at ages 18 and 25 years and 10 and 18 years, respectively, and compared with matched term-born controls. Single-breath D_LCO was measured at two oxygen pressures, with subcomponents (membrane diffusion (D_M) and pulmonary capillary blood volume (V_C)) calculated using the Roughton–Forster equation.

Results

Age-, sex- and height-standardised transfer coefficients for carbon monoxide (K_CO) and D_LCO were reduced in EP compared with term-born subjects, and remained so during puberty and early adulthood (p-values for all time-points and both cohorts ≤0.04), whereas alveolar volume (V_A) was similar. Development occurred in parallel to term-born controls, with no signs of pubertal catch-up growth nor decline at age 25 years (p-values for lack of parallelism within cohorts 0.99, 0.65, 0.71, 0.94 and 0.44 for z-D_LCO, z-V_A, z-K_CO, D_M and V_C, respectively). Split by membrane and blood volume components, findings were less clear; however, membrane diffusion seemed most affected.

Conclusions

Pulmonary diffusing capacity was reduced in EP compared with term-born subjects, and development from childhood to adulthood tracked in parallel to term-born subjects, with no signs of catch-up growth nor decline at age 25 years.

Pulmonary diffusing capacity following extremely preterm (EP) birth was reduced compared with term-born subjects. From mid-childhood to adulthood, development tracked in parallel in the EP and term-born groups, with preterms following lower trajectories.https://bit.ly/3ARPD7D

2018 Update on Pediatric Medical Overuse: A Review

IMPORTANCE

Efforts to combat medical overuse have gained traction in recent years, but success has been intermittent and shortcomings have been recognized. A commitment to a strong evidence base is needed to more broadly engage clinicians and reduce overuse.

OBSERVATIONS

A structured MEDLINE search and a manual review of tables of contents from selected high-impact journals was performed to identify original research published in 2017 relevant to pediatric overuse. Articles were scored from low to high for 3 categories: quality of methods, magnitude of potential harm, and number of patients potentially harmed. The top-scoring articles presented in this review highlight examples of safe reductions in treatment intensity, including in the setting of cancer, appendicitis, acute respiratory tract infection, and elective anesthesia. This year's articles also provide cautionary examples of rational interventions adopted without a full understanding of potential harms, including pharmacologic migraine therapies, docosahexaenoic acid supplementation for preterm neonates, tight glycemic control for individuals with critically illness, and prophylactic antibiotics for children with vesicoureteral reflux.

CONCLUSIONS AND RELEVANCE

The articles represent high-quality, original research from 2017 that may help mitigate overuse. These works should be fundamental to the maturation of the pediatric overuse field.

Tidal Breathing Measurements at Discharge and Clinical Outcomes in Extremely Low Gestational Age Neonates

RATIONALE

The relationship between respiratory function at hospital discharge and the severity of later respiratory disease in extremely low gestational age neonates is not well defined.

OBJECTIVES

To test the hypothesis that tidal breathing measurements near the time of hospital discharge differ between extremely premature infants with bronchopulmonary dysplasia (BPD) or respiratory disease in the first year of life and those without these conditions.

METHODS

Study subjects were part of the PROP (Prematurity and Respiratory Outcomes Program) study, a longitudinal cohort study of infants born at less than 29 gestational weeks followed from birth to 1 year of age. Respiratory inductance plethysmography was used for tidal breathing measurements before and after inhaled albuterol 1 week before anticipated hospital discharge. Infants were breathing spontaneously and were receiving less than or equal to 1 L/min nasal cannula flow at 21% to 100% fraction of inspired oxygen. A survey of respiratory morbidity was administered to caregivers at 3, 6, 9, and 12 months corrected age to assess for respiratory disease. We compared tidal breathing measurements in infants with and without BPD (oxygen requirement at 36 wk) and with and without respiratory disease in the first year of life. Measurements were also performed in a comparison cohort of term infants.

RESULTS

A total of 765 infants survived to 36 weeks postmenstrual age, with research-quality tidal breathing data in 452 out of 564 tested (80.1%). Among these 452 infants, the rate of postdischarge respiratory disease was 65.7%. Compared with a group of 18 term infants, PROP infants had abnormal tidal breathing patterns. However, there were no clinically significant differences in tidal breathing measurements in PROP infants who had BPD or who had respiratory disease in the first year of life compared with those without these diagnoses. Bronchodilator response was not significantly associated with respiratory disease in the first year of life.

CONCLUSIONS

Extremely premature infants receiving less than 1 L/min nasal cannula support at 21% to 100% fraction of inspired oxygen have tidal breathing measurements that differ from term infants, but these measurements do not differentiate those preterm infants who have BPD or will have respiratory disease in the first year of life from those who do not. Clinical trial registered with www.clinicaltrials.gov (NCT01435187).

Implementing Co-Regulated Feeding with Mothers of Preterm Infants

PURPOSE

The purpose of this study is to describe implementation of the Co-Regulated Feeding Intervention (CoReg), when provided by mothers and guided by intervention nurses trained in methods of guided participation (GP). Co-regulated feeding intervention aims to prevent stress during feeding and ease the challenge very preterm (VP) infants experience coordinating breathing and swallowing during the early months. Guided participation is a participatory learning method to guide the complex learning required for mothers.

STUDY DESIGN AND METHODS

Sixteen mothers of 17 VP infants participated. Each mother received a median of five intervention sessions during the infant's transition to oral feeding. Intervention field notes, audio recordings of the sessions, and video recordings of the nurse-guided feedings were reviewed, organized, and content analyzed to evaluate implementation.

RESULTS

The co-regulated feeding intervention was well received by mothers; enrollment, participation, and retention rates were high. Most mothers chose to spread out the intervention sessions across the transition period. Scheduling sessions was the greatest barrier. Mothers had competing demands and infant readiness to eat could not be predicted. The top five issues identified as needing attention by the mother or nurse included reading cues, coregulating breathing, providing motoric stability, regulating milk flow, and providing rest periods. Main GP strategies included joint attention with the mother to the dyad's feeding challenges, auditory assessment of breathing and swallowing, and reflection with planning for future feedings using video playback.

CLINICAL IMPLICATIONS

Nurse presence while mothers feed affords rich opportunities to guide coregulated, cue-based feeding. Co-regulated feeding intervention would be enhanced if mothers are guided by the bedside nurse.

Lung function at term in extremely preterm-born infants: a regional prospective cohort study

OBJECTIVES

To compare lung function of extremely preterm (EP)-born infants with and without bronchopulmonary dysplasia (BPD) with that of healthy term-born infants, and to determine which perinatal characteristics were associated with lung function at term and how predictive these measurements were for later respiratory health in EP-born infants.

METHODS

Perinatal variables were recorded prospectively, and tidal breathing parameters were measured at term-equivalent age using electromagnetic inductance plethysmography. Respiratory morbidity was defined by hospital readmissions and/or treatment with asthma medications during the first year of life.

RESULTS

Fifty-two EP-born infants (mean gestational age 26¹, range 22⁶-27⁶ weeks) and 45 term-born infants were included. There was evidence of significant airway obstruction, higher tidal volumes and increased minute ventilation in the EP-born infants with and without BPD, although generally more pronounced for those with BPD. Male gender, antenatal steroids and number of days on continuous positive airway pressure were associated with lung function outcomes at term. A prediction model incorporating two unrelated tidal breathing parameters, BPD, birth weight z-score and gender, predicted respiratory morbidity in the first year of life with good accuracy (area under the curve 0.818, sensitivity and specificity 81.8% and 75.0%, respectively).

CONCLUSION

Lung function measured at term-equivalent age was strikingly abnormal in EP-born infants, irrespective of BPD. Tidal breathing parameters may be of value in predicting future pulmonary health in infants born premature.

TRIAL REGISTRATION NUMBER

NCT01150396; Results.

Docosahexaenoic Acid and Bronchopulmonary Dysplasia in Preterm Infants

BACKGROUND

Studies in animals and in humans have suggested that docosahexaenoic acid (DHA), an n-3 long-chain polyunsaturated fatty acid, might reduce the risk of bronchopulmonary dysplasia, but appropriately designed trials are lacking.

METHODS

We randomly assigned 1273 infants born before 29 weeks of gestation (stratified according to sex, gestational age [<27 weeks or 27 to <29 weeks], and center) within 3 days after their first enteral feeding to receive either an enteral emulsion providing DHA at a dose of 60 mg per kilogram of body weight per day or a control (soy) emulsion without DHA until 36 weeks of postmenstrual age. The primary outcome was bronchopulmonary dysplasia, defined on a physiological basis (with the use of oxygen-saturation monitoring in selected infants), at 36 weeks of postmenstrual age or discharge home, whichever occurred first.

RESULTS

A total of 1205 infants survived to the primary outcome assessment. Of the 592 infants assigned to the DHA group, 291 (49.1% by multiple imputation) were classified as having physiological bronchopulmonary dysplasia, as compared with 269 (43.9%) of the 613 infants assigned to the control group (relative risk adjusted for randomization strata, 1.13; 95% confidence interval [CI], 1.02 to 1.25; P=0.02). The composite outcome of physiological bronchopulmonary dysplasia or death before 36 weeks of postmenstrual age occurred in 52.3% of the infants in the DHA group and in 46.4% of the infants in the control group (adjusted relative risk, 1.11; 95% CI, 1.00 to 1.23; P=0.045). There were no significant differences between the two groups in the rates of death or any other neonatal illnesses. Bronchopulmonary dysplasia based on a clinical definition occurred in 53.2% of the infants in the DHA group and in 49.7% of the infants in the control group (P=0.06).

CONCLUSIONS

Enteral DHA supplementation at a dose of 60 mg per kilogram per day did not result in a lower risk of physiological bronchopulmonary dysplasia than a control emulsion among preterm infants born before 29 weeks of gestation and may have resulted in a greater risk. (Funded by the Australian National Health and Medical Research Council and others; Australian New Zealand Clinical Trials Registry number, ACTRN12612000503820 .).

Perinatal factors associated with long-term respiratory sequelae in extremely low birthweight infants

OBJECTIVE

To assess lung function at 8 years old in extremely low birthweight (ELBW) survivors and to identify perinatal determinants associated with impaired lung function.

DESIGN

Retrospective cohort study.

SETTING

Level III neonatal intensive care unit.

PATIENTS

ELBW survivors born in 1990-2004 with available spirometry at 8 years old were studied. Children were excluded if they had a Wechsler Intelligence Scale for Children Third Edition full IQ <70.

MAIN OUTCOME MEASURES

Multivariate logistic regression analysis was used to identify perinatal determinants associated with airway obstruction (forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio <80%) at school age and the predictive power of potential determinants. Potential risk factors and predictors assessed in this study were gestational age, birth weight, small for gestational age, sex, chorioamnionitis, premature rupture of membranes, antenatal steroids, surfactant administration, respiratory distress syndrome, postnatal steroids, severe bronchopulmonary dysplasia and bubbly/cystic appearances of the lungs by X-ray during the neonatal period.

RESULTS

Of 656 ELBW survivors, 301 (45.9%) had attended a school-age follow-up at 8 years old. A total of 201 eligible children completed the lung function test. Bubbly/cystic appearance of the lungs (OR 4.84, 95% CI 1.26 to 18.70) was associated with a low FEV1/FVC ratio. Children with bubbly/cystic appearance had characteristics of immaturity and intrauterine inflammation.

CONCLUSIONS

Within a cohort of ELBW infants, a bubbly/cystic appearance of the lungs in the neonatal period was the strongest determinant of a low FEV1/FVC ratio at school age.

Respiratory consequences of prematurity: evolution of a diagnosis and development of a comprehensive approach

Bronchopulmonary dysplasia (BPD) is the most common respiratory consequence of premature birth and contributes to significant short- and long-term morbidity, mortality and resource utilization. Initially defined as a radiographic, clinical and histopathological entity, the chronic lung disease known as BPD has evolved as obstetrical and neonatal care have improved the survival of lower gestational age infants. Now, definitions based on the need for supplementary oxygen at 28 days and/or 36 weeks provide a useful reference point in the neonatal intensive-care unit (NICU), but are no longer based on histopathological findings, and are neither designed to predict longer term respiratory consequences nor to study the evolution of a multifactorial disease. The aims of this review are to critically examine the evolution of the diagnosis of BPD and the challenges inherent to current classifications. We found that the increasing use of respiratory support strategies that administer ambient air without supplementary oxygen confounds oxygen-based definitions of BPD. Furthermore, lack of reproducible, genetic, biochemical and physiological biomarkers limits the ability to identify an impending BPD for early intervention, quantify disease severity for standardized classification and approaches and reliably predict the long-term outcomes. More comprehensive, multidisciplinary approaches to overcome these challenges involve longitudinal observation of extremely preterm infants, not only those with BPD, using genetic, environmental, physiological and clinical data as well as large databases of patient samples. The Prematurity and Respiratory Outcomes Program (PROP) will provide such a framework to address these challenges through high-resolution characterization of both NICU and post-NICU discharge outcomes.