Pulmonary outcome in extremely low birth weight infants

Using continuous overnight pulse oximetry to guide home oxygen therapy in chronic neonatal lung disease

AIM

The aims of this study are: (i) to survey the knowledge of paediatric clinicians using overnight continuous pulse oximetry data to guide management of infants with chronic neonatal lung disease (CNLD); (ii) to assess the ability of paediatric clinicians to interpret overnight continuous pulse oximetry data; and (iii) to describe the overnight oximetry interpretation practices of paediatric respiratory specialists.

METHODS

Paediatric clinicians from three tertiary teaching hospitals completed an anonymous survey regarding overnight continuous pulse oximetry in chronic neonatal lung disease. Using a modified Delphi technique, paediatric respiratory specialists participated in a concordance exercise and discussions to establish consensus interpretations for 25 oximetry studies. Paediatric clinicians were invited to complete the same exercise as a comparison.

RESULTS

Self-rated knowledge from 74 surveyed clinicians was proportional to clinical experience. Twenty paediatric clinicians and nine paediatric respiratory specialists completed the oximetry exercise with scores of 64% (κ = 0.25) and 80% (κ = 0.45), respectively. Individual parameters like a mean peripheral arterial haemoglobin saturation (SpO₂ ) below 93% and percentage time spent below SpO₂ 93% correlated poorly with the consensus interpretations. Paediatric respiratory specialists instead relied on visual analysis of SpO₂ waveforms, utilising the frequency and depth of desaturations to guide management.

CONCLUSION

Interpretation of overnight oximetry data is variable amongst both paediatric clinicians and respiratory specialists. This likely reflects inadequate evidence defining clinically significant intermittent hypoxaemia, whether in terms of desaturation duration, frequency or nadir.

Impact of targeted-volume ventilation on pulmonary dynamics in preterm infants with respiratory distress syndrome

BACKGROUND

Mechanical ventilation is an essential therapy in the treatment of respiratory failure in preterm infants. However, optimal ventilation strategy continues to be difficult to define.

OBJECTIVE

To compare the effects of volume guarantee (VG) combined with intermittent mandatory ventilation (SIMV) and VG combined with pressure support ventilation (PSV) on the pulmonary mechanics and short term prognosis in preterm infants with respiratory distress syndrome.

METHODS

Infants of <32 weeks gestational age ventilated for respiratory distress syndrome were randomized to receive either SIMV + VG or PSV + VG. The patient characteristics, ventilator variables including PIP, PEEP, MAP, VT, dynamic compliance, resistance, C20/C, and neonatal outcomes (IVH, ROP, oxygen dependency at 28th postnatal day and 36 weeks of PMA), mortality and extubation failure were recorded in each groups.

RESULTS

Thirty-four infants were enrolled in to the study: 19 patients were randomized to the SIMV + VG group, and 15 patients to the PSV + VG group. No significant differences were observed between the two groups in terms of the birth weight, gestational age, gender, multiple pregnancy, delivery mode, and antenatal steroid treatment. The respiratory and ventilatory parameters were similar in the groups. The need for reintubation were common in SIMV + VG group (P < 0.01).

CONCLUSIONS

Volume guaranteed ventilation combined with PSV may be a convenient method for preterm infants with RDS in terms of reducing postextubation atelectasis and the need for reintubation. Pediatr Pulmonol. 2017;52:213-216. © 2016 Wiley Periodicals, Inc.

Evaluation of bedside pulmonary function in the neonate: From the past to the future

Pulmonary function testing and monitoring plays an important role in the respiratory management of neonates. A noninvasive and complete bedside evaluation of the respiratory status is especially useful in critically ill neonates to assess disease severity and resolution and the response to pharmacological interventions as well as to guide mechanical respiratory support. Besides traditional tools to assess pulmonary gas exchage such as arterial or transcutaenous blood gas analysis, pulse oximetry, and capnography, additional valuable information about global lung function is provided through measurement of pulmonary mechanics and volumes. This has now been aided by commercially available computerized pulmonary function testing systems, respiratory monitors, and modern ventilators with integrated pulmonary function readouts. In an attempt to apply easy-to-use pulmonary function testing methods which do not interfere with the infant́s airflow, other tools have been developed such as respiratory inductance plethysmography, and more recently, electromagnetic and optoelectronic plethysmography, electrical impedance tomography, and electrical impedance segmentography. These alternative technologies allow not only global, but also regional and dynamic evaluations of lung ventilation. Although these methods have proven their usefulness for research applications, they are not yet broadly used in a routine clinical setting. This review will give a historical and clinical overview of different bedside methods to assess and monitor pulmonary function and evaluate the potential clinical usefulness of such methods with an outlook into future directions in neonatal respiratory diagnostics.

Volume-targeted ventilation is more suitable than pressure-limited ventilation for preterm infants: a systematic review and meta-analysis

OBJECTIVE

To assess the effect of volume-targeted ventilation (VTV) compared with pressure-limited ventilation (PLV) in preterm infants.

METHOD

We searched the Cochrane Library (Issue 3, 2013), PubMed (1966 to 5 March 2013), China National Knowledge Infrastructure (CNKI) and periodical databases (1979 to 5 March 2013). We selected randomised controlled trials (RCTs) and quasi-RCTs of VTV versus PLV as active interventions in preterm infants. We performed meta-analyses using the Cochrane statistical package RevMan 5.0.

RESULTS

Eighteen trials met our inclusion criteria. There was no evidence that VTV modes reduced the incidence of death (relative risk (RR) 0.73, 95% CI 0.51 to 1.05). The use of VTV modes resulted in a reduction in the incidence of bronchopulmonary dysplasia (BPD) (RR 0.61, 95% CI 0.46 to 0.82) and duration of mechanical ventilation (mean difference (MD) -2.0 days, 95% CI -3.14 to -0.86). VTV modes also resulted in reductions in intraventricular haemorrhage (IVH) (RR 0.65, 95% CI 0.42 to 0.99), grade 3/4 IVH (RR 0.55, 95% CI 0.39 to 0.79), periventricular leukomalacia (PVL) (RR 0.33, 95% CI 0.15 to 0.72), pneumothorax (RR 0.52, 95% CI 0.29 to 0.93), failure of primary mode of ventilation (RR 0.64, 95% CI 0.43 to 0.94), hypocarbia (RR 0.56, 95% CI 0.33 to 0.96), mean airway pressure (MD -0.54 cmH2O, 95% CI -1.05 to -0.02) and days of supplemental oxygen administration (MD -1.68 days, 95% CI -2.47 to -0.88).

CONCLUSIONS

Preterm infants ventilated using VTV modes had reduced duration of mechanical ventilation, incidence of BPD, failure of primary mode of ventilation, hypocarbia, grade 3/4 IVH, pneumothorax and PVL compared with preterm infants ventilated using PLV modes. There was no evidence that infants ventilated with VTV modes had reduced death compared to infants ventilated using PLV modes.

Influência da posição prona na oxigenação, frequência respiratória e na força muscular nos recém-nascidos pré-termo em desmame da ventilação mecânica

OBJETIVO: Verificar a influência do posicionamento do recém-nascido prematuro sobre a força da musculatura respiratória, oxigenação e frequência respiratória. MÉTODOS: Estudo transversal com amostra pareada de recém-nascidos com idade gestacional inferior a 34 semanas, intubados, em processo final de desmame de ventilação mecânica. Foram excluídos aqueles com malformações, síndromes genéticas, doenças neuromusculares, traqueostomizados e em pós-operatório de cirurgias abdominais ou torácicas. As medidas de pressão inspiratória máxima foram aferidas utilizando-se manovacuômetro digital; a frequência respiratória através da observação das incursões respiratórias das crianças em um minuto e a saturação de oxigênio por oxímetro, nas posturas prona e supino. Os testes estatísticos aplicados foram Kruskal-Wallis, o teste t de Student e o coeficiente de correlação de Pearson, sendo significante p<0,05. RESULTADOS: Foram estudadas 45 crianças com síndrome do desconforto respiratório. A idade gestacional média foi de 30,4 semanas e o peso médio ao nascer de 1522g. Os valores de saturação de oxigênio foram mais elevados (p<0,001) e os de pressão inspiratória máxima mais baixos (p<0,001) na posição prona. Os valores de frequência respiratória foram semelhantes nas duas posições estudadas (p=0,072). CONCLUSÕES: Observaram-se menores valores de pressão inspiratória além de aumento da saturação de oxigênio na posição prona quando comparada à supino. Em relação à frequência respiratória, não foi observada variação entre as posturas prona e supino.

Conductive hearing loss in children with bronchopulmonary dysplasia: a longitudinal follow-up study in children aged between 6 and 24 months

AIMS

To determine the occurrence of isolated and recurrent episodes of conductive hearing loss (CHL) during the first two years of life in very low birth weight (VLBW) infants with and without bronchopulmonary dysplasia (BPD). STUDY DESIGN, SUBJECTS AND OUTCOME MEASURES: In a longitudinal clinical study, 187 children were evaluated at 6, 9, 12, 15 18 and 24 months of age by visual reinforcement audiometry, tympanometry and auditory brain response system.

RESULTS

Of the children with BPD, 54.5% presented with episodes of CHL, as opposed to 34.7% of the children without BPD. This difference was found to be statistically significant. The recurrent or persistent episodes were more frequent among children with BPD (25.7%) than among those without BPD (8.3%). The independent variables that contributed to this finding were small for gestational age and a 5 min Apgar score.

CONCLUSIONS

Recurrent CHL episodes are more frequent among VLBW infants with BPD than among VLBW infants without BPD.

Peri-operative management of paediatric patients undergoing cardiac surgery--focus on respiratory aspects of care

Children requiring cardiac surgery present particular challenges in peri-operative respiratory management. The wide variety of conditions and operations and their varied impact on respiratory function makes dialogue with related medical staff essential. In most circumstances, cardiac performance is the main determinant of respiratory outcomes. Changing cardiologic and surgical approaches have combined to diminish the severity and frequency of pulmonary hypertensive issues and new treatment modalities are simplifying the intensive care approach. Patients with Down's syndrome and 22q11 deletion syndrome present particular issues related to anatomy, physiology and respiratory function. Certain conditions, including tetralogy of Fallot and cavopulmonary connections, present unique circumstances where respiratory management, sometimes including extubation, may assist in optimisation of cardiac performance. These and other conditions highlight the complexities of cardiopulmonary interactions. Cardiac performance remains the principal determinant of outcome after paediatric cardiac surgery and has the biggest impact on respiratory function.

TNF-a and IL-10 levels in tracheobronchial lavage of ventilated preterm infants and subsequent lung function

The role of airway inflammation in ventilated preterm newborns and the risk factors associated with the development of chronic lung disease are not well understood. Our objective was to analyze the association of the airway inflammatory response in ventilated preterm infants by serial measurements of TNF-alpha and IL-10 in tracheobronchial lavage (TBL) with perinatal factors and lung function measured early in life. A series of TBL samples were collected from ventilated preterm infants (less than 32 weeks of gestational age) and concentrations of TNF-alpha and IL-10 were measured by ELISA. Pulmonary function tests were performed after discharge by the raised volume rapid compression technique. Twenty-five subjects were recruited and 70 TBL samples were obtained. There was a significant positive association between TNF-alpha and IL-10 levels and length of time between the rupture of the amniotic membranes and delivery (r = 0.65, P = 0.002, and r = 0.57, P < 0.001, respectively). Lung function was measured between 1 and 22 weeks of corrected age in 10 patients. Multivariable analysis with adjustment for differences in lung volume showed a significant negative association between TNF-alpha levels and forced expiratory flow (FEF(50); r = -0.6; P = 0.04), FEF(75) (r = -0.76; P = 0.02), FEF(85) (r = -0.75; P = 0.03), FEF(25-75) (-0.71; P = 0.02), and FEV(0.5) (r = -0.39; P = 0.03). These data suggest that TNF-alpha levels in the airways during the first days of life were associated with subsequent lung function abnormalities measured weeks or months later.

Staged operations for posthemorrhagic hydrocephalus in extremely low-birth-weight infants with preceding stoma creation after bowel perforation: surgical strategy

CASE REPORT

We report a complicated extremely low-birth-weight (ELBW) infant with posthemorrhagic hydrocephalus after intraventricular hemorrhage and preceding stoma creation after bowel perforation who was treated with staged operations, including shunting and external ventricular drainage. The first operation was a temporary valveless ventriculoperitoneal (VP) shunt placement until the time of the stoma closure. The stoma was successfully closed 3 months after the first operation when the peritoneal tube was drawn out from the chest wall and the VP shunt system was temporarily used as an external drainage with a long subcutaneous tunnel. One month after the second operation, final VP shunt placement was performed after good healing of bowel anastomosis was surely confirmed. The previous peritoneal shunt tube was cut behind the ear, removed, and replaced with a valve-regulated VP shunt system.

CONCLUSION

This staged strategy is a safe and feasible option for complicated ELBW infants with preceding stoma and hydrocephalus.

A rational approach to home oxygen use in infants and children

The provision of supplemental oxygen for infants and children with hypoxaemia is expensive but advantageous because it facilitates earlier discharge from hospital and enhances quality of life in the home setting. It is seen as potentially cost effective and family friendly. However, the prescription of supplemental oxygen varies greatly between neonatologists, paediatric respiratory physicians and paediatric cardiologists. There is a lack of consensus on appropriate indications for prescribing oxygen, desirable oxygen targets and clinically significant immediate and longer-term outcome measures. Of the limited studies available, most are small studies reporting the treatment of infants with chronic neonatal lung disease with inconsistent outcome measures. Such data are not readily extrapolated to older children, who are also poorly served by existing data in adult studies. Further delineation of the indications for home oxygen therapy is required together with appropriately designed and funded multicentre trials to provide evidence for optimal oxygen therapy.

Lung function tests in neonates and infants with chronic lung disease: lung and chest-wall mechanics

This is the fifth paper in a review series that summarizes available data and critically discusses the potential role of lung function testing in infants and young children with acute neonatal respiratory disorders and chronic lung disease of infancy (CLDI). This review focuses on respiratory mechanics, including chest-wall and tissue mechanics, obtained in the intensive care setting and in infants during unassisted breathing. Following orientation of the reader to the subject area, we focused comments on areas of enquiry proposed in the introductory paper to this series. The quality of the published literature is reviewed critically with respect to relevant methods, equipment and study design, limitations and strengths of different techniques, and availability and appropriateness of reference data. Recommendations to guide future investigations in this field are provided. Numerous different methods have been used to assess respiratory mechanics with the aims of describing pulmonary status in preterm infants and assessing the effect of therapeutic interventions such as surfactant treatment, antenatal or postnatal steroids, or bronchodilator treatment. Interpretation of many of these studies is limited because lung volume was not measured simultaneously. In addition, populations are not comparable, and the number of infants studied has generally been small. Nevertheless, results appear to support the pathophysiological concept that immaturity of the lung leads to impaired lung function, which may improve with growth and development, irrespective of the diagnosis of chronic lung disease. To fully understand the impact of immaturity on the developing lung, it is unlikely that a single parameter such as respiratory compliance or resistance will accurately describe underlying changes. Assessment of respiratory mechanics will have to be supplemented by assessment of lung volume and airway function. New methods such as the low-frequency forced oscillation technique, which differentiate the tissue and airway components of respiratory mechanics, are likely to require further development before they can be of clinical significance.

Effects of pressure support ventilation plus volume guarantee vs. high-frequency oscillatory ventilation on lung inflammation in preterm infants

The aim of the present study was to evaluate if high-frequency oscillatory ventilation (HFOV) might reduce lung inflammation in preterm infants with infant respiratory distress syndrome (RDS) in comparison with the early application of another potentially lung-protective ventilation strategy, such as pressure support ventilation plus volume guarantee (PSV + VG). Infants at less than 30 weeks of gestation with RDS were enrolled consecutively in the study if they required mechanical ventilation, and were randomly allocated to receive HFOV or PSV + VG. Bronchial aspirate samples for the measurement of interleukin (IL)-1beta, IL-8, and IL-10 were obtained before surfactant treatment (T1), after 6-18 hr of ventilation (T2), after 24-48 hr of ventilation (T3), and before extubation (T4). Thirteen patients were enrolled in the HFOV group, and 12 in the PSV + VG group. The mean values of IL-1beta, IL-8, and IL-10 at T4 were lower in the HFOV group than in the PSV + VG group. The present study demonstrates that early treatment with HFOV is associated with a reduction of lung inflammation in comparison with PSV + VG in preterm infants with RDS.

Tracheal gas insufflation-augmented continuous positive airway pressure in a spontaneously breathing model of neonatal respiratory distress

Respiratory distress syndrome (RDS) in neonates is characterized by labored breathing and poor gas exchange, often requiring ventilatory support. Continuous positive airway pressure (CPAP) is a preferred intervention to support spontaneous ventilatory efforts by sustaining lung volume recruitment, while it prevents derecruitment during exhalation by maintaining end-expiratory pressure. However, CO2 retention during CPAP often results in the need for mechanical ventilation. Since tracheal gas insufflation (TGI) promotes CO2 elimination by reducing prosthetic dead space, we hypothesized that TGI used with CPAP may reduce the need for more invasive therapies. The objective of this study was to evaluate the physiologic effect of TGI with CPAP in a spontaneously breathing model of acute lung injury with respect to gas exchange and pulmonary mechanics. Nineteen spontaneously breathing neonatal pigs (2.4 +/- 0.4 kg) were anesthetized, sedated, instrumented, and placed on CPAP at 5 cmH2O. All piglets were injured with intravenous oleic acid (0.08 ml/kg), and then randomized to receive CPAP with TGI (TGI; n = 9) or CPAP alone (control; n = 10). FiO2 was titrated at 0.05 every 15 min during the protocol to maintain SaO2 > 93%. Vital signs, arterial blood gases, pulmonary mechanics, and thoracoabdominal motion (TAM) were evaluated 30 min after injury and at 1-hr intervals for 4 hr. Following the 4-hr measurement, the piglets were sacrificed and the lungs were grossly examined. After initiation of treatment, we found that the PaCO2 was lower (33.1 +/- 5.0 vs. 47.0 +/- 10.3 mmHg; P < 0.01), while the oxygenation indices were greater (PaO2, SaO2, a/A ratio; P < 0.01) in the TGI group than with control animals. Subsequently, the pH was greater (7.45 +/- 0.08 vs. 7.36 +/- 0.08; P < 0.01) and closer to baseline values with TGI. By 4 hr, the FiO2 was titrated lower (0.37 +/- 0.06 vs. 0.49 +/- 0.15; P < 0.05) and ventilation was accomplished with a lower minute ventilation (MV) in the TGI group than in the control group (445 +/- 113 vs. 581 +/- 223 ml/kg/min; P < 0.01). Respiratory compliance was greater with TGI than control (0.76 +/- 0.13 vs. 0.63 +/- 0.11 ml/cmH2O/kg; P < 0.01), whereas resistance and TAM were similar between groups. We conclude that the use of TGI with CPAP in the treatment of RDS results in improved gas exchange and pulmonary mechanics. As such, TGI-augmented CPAP may prevent infants from requiring more invasive ventilation by reducing CO2 retention.

Early indicators of chronic lung disease in preterm infants with respiratory distress syndrome and their inhibition by melatonin

Improved survival from advances in neonatal care has resulted in an increased number of infants at risk for chronic lung disease (CLD). Recently, it was reported that inflammatory mediators such as interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF)-alpha and IL-8 are present in higher concentrations in lung lavage from babies who develop CLD. Previously, we found that melatonin reduced the rises in proinflammatory cytokines (IL-6, IL-8 and TNF-alpha) and nitrite/nitrate levels in the serum of preterm newborns with respiratory distress syndrome (RDS). The values correlated with gestational age and iatrogenic trauma in the form of oxygen exposure and mechanical ventilation. Increased concentrations of proinflammatory cytokines may, therefore, be the most valuable early indicator of developing CLD and these measurements may assist in selecting infants for interventions such as melatonin treatment or more selective blockage of components of inflammation. In the current study, we extend the original observations and report results in which 120 newborns diagnosed with RDS were either treated with melatonin (60 children) or given placebo (60 children). The cytokine measures were consistent with the previously reported findings and showed that melatonin reduced these values and also lowered nitrite/nitrate levels in serum of newborns with respiratory distress. Furthermore, when nonmelatonin-treated newborns who developed CLD (eight infants) were examined separately, they had levels of IL-6, IL-8, TNF-alpha and nitrite/nitrate values much higher than those in children who did not develop CLD. Two of the nonmelatonin-treated newborns died while no children who received melatonin died. Melatonin was well tolerated by the newborns.

Lung mechanics and high-resolution computed tomography of the chest in very low birth weight premature infants

CONTEXT

Premature infant lung development may be affected by lung injuries during the first few weeks of life. Lung injuries have been associated with changes in lung mechanics.

OBJECTIVE

To evaluate an association between lung mechanics and lung structural alterations in very low birth weight infants (birth weight less than 1500 g).

DESIGN

A cross-sectional evaluation of pulmonary mechanics (lung compliance and lung resistance) and high resolution computed tomography of the chest at the time of discharge, in 86 very low birth weight infants born at Instituto Fernandes Figueira, a tertiary public healthcare institution in Rio de Janeiro, Brazil. Lung compliance and resistance were measured during quiet sleep. High resolution computed tomography was performed using Pro Speed-S equipment.

MAIN MEASUREMENTS

Statistical analysis was performed by means of variance analysis (ANOVA/Kruskal Wallis). The significance level was set at 0.05.

RESULTS

Abnormal values for both lung compliance and lung resistance were found in 34 babies (43%), whereas 20 (23.3%) had normal values for both lung compliance and lung resistance. The mean lung compliance and lung resistance for the group were respectively 1.30 ml/cm H2O/kg and 63.7 cm H2O/l/s. Lung alterations were found via high-resolution computed tomography in 62 (72%) infants. Most infants showed more than one abnormality, and these were described as ground glass opacity, parenchymal bands, atelectasis and bubble/cyst. The mean compliance values for infants with normal (1.49 ml/cm H2O/kg) high resolution computed tomography, 1 or 2 abnormalities (1.31 ml/cm H2O/kg) and 3 or more abnormalities (1.16 ml/cm H2O/kg) were significantly different (p=0.015). Our data were insufficient to find any association between lung resistance and the number of alterations via high-resolution computed tomography.

CONCLUSION

The results show high prevalence of lung functional and tomographic abnormalities in asymptomatic very low birth weight infants at the time of discharge. They also show an association between lung morphological and functional abnormalities.

Rehospitalization of extremely-low-birth-weight infants in first 2 years of life

AIMS

To determine whether (1) chronic lung disease (CLD) is the prime reason for extremely-low-birth-weight (ELBW) infant readmission during the first 2 years of life, (2) surfactant and other advanced therapies have reduced ELBW infant readmissions, (3) home oxygen therapy (HOT) is efficacious for this group.

STUDY DESIGN

The hospital records of these ELBW infants were reviewed retrospectively. Data on age, diagnosis, treatment, and duration of each hospitalization were compiled and analyzed for their association to CLD and to readmission for CLD and other reasons.

SUBJECTS

All 60 surviving infants with a birth body weight of less than 1001 g (ELBW) born from January 1993 to February 1998 were followed up to 2 years (mean 20.4 +/- 7.4 months) to evaluate their respiratory outcome.

RESULTS

Forty-two percent of these infants developed CLD. Upon discharge from the hospital, 28% (7/25) of the patients were given HOT for a median period of 60 days. Of the 47 ELBW infants who were studied the entire 2-year period, 72% were readmitted. Infants with CLD were readmitted more frequently (p=0.045) and had longer hospital stays during the first 2 years of life (p=0.034) than those without CLD. Respiratory illness was the main reason for readmission (55%) of these ELBW infants. The incidence of readmission due to respiratory tract infection was not significantly different in infants with CLD (61%) and infants without respiratory complications (44%) (p=0.159).

CONCLUSIONS

Infants with CLD (whether receiving HOT or not) showed no higher readmission rate due to respiratory infection, but the HOT group did have higher morbidity. The premature lung itself rather than the presence of CLD, as we would expect, makes ELBW infants more prone to readmission for respiratory illness.