Non-invasive ventilatory support in neonates: An evidence-based update.

Non-invasive ventilatory support (NIV) is considered the gold standard in the care of preterm infants with respiratory distress syndrome (RDS). NIV from birth is superior to mechanical ventilation (MV) for the prevention of death or bronchopulmonary dysplasia (BPD), with a number needed to treat between 25 and 35. Various methods of NIV are available, some of them extensively researched and with well proven efficacy, whilst others are needing further research. Nasal continuous positive airway pressure (nCPAP) has replaced routine invasive mechanical ventilation (MV) for the initial stabilization and the treatment of RDS. Choosing the most suitable form of NIV and the most appropriate patient interface depends on several factors, including gestational age, underlying lung pathophysiology and the local facilities. In this review, we present the currently available evidence on NIV as primary ventilatory support to preventing intubation and for secondary ventilatory support, following extubation. We review nCPAP, nasal high-flow cannula, nasal intermittent positive airway pressure ventilation, bi-level positive airway pressure, nasal high-frequency oscillatory ventilation and nasal neurally adjusted ventilatory assist modes. We also discuss most suitable NIV devices and patient interfaces during resuscitation of the newborn in the delivery room.

Rate of rise of total serum bilirubin in very low birth weight preterm infants.

BACKGROUND: To assess the postnatal rate of rise (ROR) of total serum bilirubin (TSB) in very low birth weight (VLBW) preterm infants, to determine risk factors associated with a rapid rise (>90th percentile), and to compare ROR and hour-specific TSB at postnatal 12-48 h with data of term infants retrieved from the literature. METHODS: Retrospective analysis of 2430 routine TSB concentrations obtained between birth and initiation of phototherapy in 483 VLBW infants. RESULTS: TSB increased by a median (interquartile range) ROR of 0.15 (0.11-0.19) mg/dL/h. The 50th percentile of TSB was below the 40th percentile of (near-)term counterparts at 12-48 h. TSB ROR correlated with the age at initiation (RS = -0.687; p < 0.001) and the duration (RS = 0.444; p < 0.001) of phototherapy. ROR >90th percentile (>0.25 mg/dL/h) was associated with lower gestational ages [27.2 (25.4-29.3) vs. 28.4 (26.4-30.4) weeks], lower birth weights [978 (665-1120) vs. 1045 (814-1300) g], and lower 5-min Apgar scores [7 (7-8) vs. 8 (7-9)]. CONCLUSION: ROR of TSB is an indicator for early and prolonged phototherapy. While hour-specific TSB and ROR at 12-48 h are lower than those reported for (near-)term infants, TSB appears to rise more rapidly in infants with low gestational age, low birth weight, and low 5-min Apgar score.

Differential impact of flow and mouth leak on oropharyngeal humidification during high-flow nasal cannula: a neonatal bench study.

BACKGROUND: Heated humidification is paramount during neonatal high-flow nasal cannula (HFNC) therapy. However, there is little knowledge about the influence of flow rate and mouth leak on oropharyngeal humidification and temperature. METHODS: The effect of the Optiflow HFNC on oropharyngeal gas conditioning was investigated at flow rates of 4, 6 and 8 L min-1 with and without mouth leak in a bench model simulating physiological oropharyngeal air conditions during spontaneous breathing. Temperature and absolute humidity (AH) were measured using a digital thermo-hygrosensor. RESULTS: Without mouth leak, oropharyngeal temperature and AH increased significantly with increasing flow (P < 0.001). Mouth leak did not affect this increase up to 6 L min-1, but at 8 L min-1, temperature and AH plateaued, and the effect of mouth leak became statistically significant (P < 0.001). CONCLUSIONS: Mouth leak during HFNC had a negative impact on oropharyngeal gas conditioning when high flows were applied. However, temperature and AH always remained clinically acceptable.

Nasal high-frequency oscillatory ventilation impairs heated humidification: A neonatal bench study.

OBJECTIVE: Nasal high-frequency oscillatory ventilation (nHFOV) is a novel mode of non-invasive ventilation used in neonates. However, upper airway obstructions due to viscous secretions have been described as specific adverse effects. We hypothesized that high-frequency oscillations reduce air humidity in the oropharynx, resulting in upper airway desiccation. Therefore, we aimed to investigate the effects of nHFOV ventilatory settings on oropharyngeal gas conditions. METHODS: NHFOV or nasal continuous positive airway pressure (nCPAP) was applied, along with heated humidification, to a previously established neonatal bench model that simulates oropharyngeal gas conditions during spontaneous breathing through an open mouth. A digital thermo-hygro sensor measured oropharyngeal temperature (T) and humidity at various nHFOV frequencies (7, 10, 13 Hz), amplitudes (10, 20, 30 cmH2 O), and inspiratory-to-expiratory (I:E) ratios (25:75, 33:66, 50:50), and also during nCPAP. RESULTS: Relative humidity was always >99%, but nHFOV resulted in lower mean T and absolute humidity (AH) in comparison to nCPAP (P < 0.001). Specifically, decreasing the nHFOV frequency and increasing nHFOV amplitude caused a decline in T and AH (P < 0.001). Mean T and AH were highest during nCPAP (T 34.8 ± 0.6°C, AH 39.3 ± 1.3 g · m-3 ) and lowest during nHFOV at a frequency of 7 Hz and an amplitude of 30 cmH2 O (T 32.4 ± 0.3°C, AH 34.7 ± 0.5 g · m-3 ). Increasing the I:E ratio also reduced T and AH (P = 0.03). CONCLUSION: Intensified nHFOV settings with low frequencies, high amplitudes, and high I:E ratios may place infants at an increased risk of upper airway desiccation. Future studies should investigate strategies to optimize heated humidification during nHFOV.

Lung function in very low birth weight infants after pharmacological and surgical treatment of patent ductus arteriosus - a retrospective analysis.

BACKGROUND: The indications and strategies for treatment of patent ductus arteriosus (PDA) are controversial, and the safety and long-term benefits of surgical PDA closure remain uncertain. The aim of this study was to compare the lung function of very low birth weight (VLBW) infants after successful PDA treatment with a cyclooxygenase inhibitor or secondary surgical ligation. METHODS: A total of 114 VLBW infants (birth weight < 1500 g), including 94 infants (82%) with a birth weight < 1000 g, who received treatment for hemodynamically significant PDA (hsPDA), were examined at a median postmenstrual age of 48 weeks. All infants were initially given pharmacological treatment, and 40 infants (35%) required PDA ligation. Lung function testing (LFT) included tidal breathing measurements, measurement of respiratory mechanics assessed by the occlusion test, whole-body plethysmography, SF6 multiple breath washout, forced expiratory flow (V'maxFRC) by the rapid thoracoabdominal compression technique, exhaled NO (FeNO), and arterialized capillary blood gas analysis. RESULTS: On the day of the LFT, the 2 groups had similar postconceptional age and body weight. However, the PDA ligation group was more immature at birth (p < 0.001) and had reduced respiratory compliance (p < 0.001), lower V'maxFRC (p = 0.006), increased airway resistance (Raw) (p < 0.001), and impaired blood gases (p < 0.001). Multivariate analysis showed that PDA surgery was an independent risk factor for increased Raw. CONCLUSION: PDA ligation after failed pharmacological treatment is associated with impaired lung function as compared to successful pharmacological closure in infants at a postmenstrual age of 48 weeks. However, only Raw was independently affected by PDA ligation, while all other differences were merely explained by patient characteristics.

Influence of mouth opening on oropharyngeal humidification and temperature in a bench model of neonatal continuous positive airway pressure.

Clinical studies show that non-invasive respiratory support by continuous positive airway pressure (CPAP) affects gas conditioning in the upper airways, especially in the presence of mouth leaks. Using a new bench model of neonatal CPAP, we investigated the influence of mouth opening on oropharyngeal temperature and humidity. The model features the insertion of a heated humidifier between an active model lung and an oropharyngeal head model to simulate the recurrent expiration of heated, humidified air. During unsupported breathing, physiological temperature and humidity were attained inside the model oropharynx, and mouth opening had no significant effect on oropharyngeal temperature and humidity. During binasal CPAP, the impact of mouth opening was investigated using three different scenarios: no conditioning in the CPAP circuit, heating only, and heated humidification. Mouth opening had a strong negative impact on oropharyngeal humidification in all tested scenarios, but heated humidification in the CPAP circuit maintained clinically acceptable humidity levels regardless of closed or open mouths. The model can be used to test new equipment for use with CPAP, and to investigate the effects of other methods of non-invasive respiratory support on gas conditioning in the presence of leaks.

Computerized wheeze detection in young infants: comparison of signals from tracheal and chest wall sensors.

Computerized wheeze detection is an established method for objective assessment of respiratory sounds. In infants, this method has been used to detect subclinical airway obstruction and to monitor treatment effects. The optimal location for the acoustic sensors, however, is unknown. The aim of this study was to evaluate the quality of respiratory sound recordings in young infants, and to determine whether the position of the sensor affected computerized wheeze detection. Respiratory sounds were recorded over the left lateral chest wall and the trachea in 112 sleeping infants (median postmenstrual age: 49 weeks) on 129 test occasions using an automatic wheeze detection device (PulmoTrack®). Each recording lasted 10 min and the recordings were stored. A trained clinician retrospectively evaluated the recordings to determine sound quality and disturbances. The wheeze rates of all undisturbed tracheal and chest wall signals were compared using Bland-Altman plots. Comparison of wheeze rates measured over the trachea and the chest wall indicated strong correlation (r ⩾ 0.93, p < 0.001), with a bias of 1% or less and limits of agreement of within 3% for the inspiratory wheeze rate and within 6% for the expiratory wheeze rate. However, sounds from the chest wall were more often affected by disturbances than sounds from the trachea (23% versus 6%, p < 0.001). The study suggests that in young infants, a better quality of lung sound recordings can be obtained with the tracheal sensor.

Current methodological and technical limitations of time and volumetric capnography in newborns.

Although capnography is a standard tool in mechanically ventilated adult and pediatric patients, it has physiological and technical limitations in neonates. Gas exchange differs between small and adult lungs due to the greater impact of small airways on gas exchange, the higher impact of the apparatus dead space on measurements due to lower tidal volume and the occurrence of air leaks in intubated patients. The high respiratory rate and low tidal volume in newborns, especially those with stiff lungs, require main-stream sensors with fast response times and minimal dead-space or low suction flow when using side-stream measurements. If these technical requirements are not fulfilled, the measured end-tidal CO2 (P et CO 2 ), which should reflect the alveolar CO2 and the calculated airway dead spaces, can be misleading. The aim of this survey is to highlight the current limitations of capnography in very young patients to avoid pitfalls associated with the interpretation of capnographic parameters, and to describe further developments.

Basic principles of respiratory function monitoring in ventilated newborns: A review.

Respiratory monitoring during mechanical ventilation provides a real-time picture of patient-ventilator interaction and is a prerequisite for lung-protective ventilation. Nowadays, measurements of airflow, tidal volume and applied pressures are standard in neonatal ventilators. The measurement of lung volume during mechanical ventilation by tracer gas washout techniques is still under development. The clinical use of capnography, although well established in adults, has not been embraced by neonatologists because of technical and methodological problems in very small infants. While the ventilatory parameters are well defined, the calculation of other physiological parameters are based upon specific assumptions which are difficult to verify. Incomplete knowledge of the theoretical background of these calculations and their limitations can lead to incorrect interpretations with clinical consequences. Therefore, the aim of this review was to describe the basic principles and the underlying assumptions of currently used methods for respiratory function monitoring in ventilated newborns and to highlight methodological limitations.

Reliability of Single-Use PEEP-Valves Attached to Self-Inflating Bags during Manual Ventilation of Neonates--An In Vitro Study.

INTRODUCTION: International resuscitation guidelines suggest to use positive end-expiratory pressure (PEEP) during manual ventilation of neonates. Aim of our study was to test the reliability of self-inflating bags (SIB) with single-use PEEP valves regarding PEEP delivery and the effect of different peak inflation pressures (PIP) and ventilation rates (VR) on the delivered PEEP. METHODS: Ten new single-use PEEP valves from 5 manufacturers were tested by ventilating an intubated 1 kg neonatal manikin containing a lung model with a SIB that was actuated by an electromechanical plunger device. Standard settings: PIP 20 cmH2O, VR 60/min, flow 8 L/min. PEEP settings of 5 and 10 cmH2O were studied. A second test was conducted with settings of PIP 40 cmH2O and VR 40/min. The delivered PEEP was measured by a respiratory function monitor (CO2SMO+). RESULTS: Valves from one manufacturer delivered no relevant PEEP and were excluded. The remaining valves showed a continuous decay of the delivered pressure during expiration. The median (25th and 75th percentile) delivered PEEP with standard settings was 3.4(2.7-3.8) cmH2O when set to 5 cmH2O and 6.1(4.9-7.1) cmH2O when set to 10 cmH2O. Increasing the PIP from 20 to 40 cmH2O led to a median (25th and 75th percentile) decrease in PEEP to 2.3(1.8-2.7) cmH2O and 4.3(3.2-4.8) cmH2O; changing VR from 60 to 40/min led to a PEEP decrease to 2.8(2.1-3.3) cmH2O and 5.0(3.5-6.2) cmH2O for both PEEP settings. CONCLUSION: Single-use PEEP valves do not reliably deliver the set PEEP. PIP and VR have an effect on the delivered PEEP. Operators should be aware of these limitations when manually ventilating neonates.

Relationship between computerized wheeze detection and lung function parameters in young infants.

OBJECTIVE: Computerized respiratory sound analysis (CORSA) has been validated in the assessment of wheeze in infants, but it is unknown whether automatically detected wheeze is associated with impaired lung function. This study investigated the relationship between wheeze detection and conventional lung function testing (LFT) parameters. METHODS: CORSA was performed using the PulmoTrack® monitor in 110 infants, of median (interquartile range) postmenstrual age 50 (46-56) weeks and median body weight 4,810 (3,980-5,900) g, recovering from neonatal intensive care. In the same session, LFT was performed, including tidal breathing measurements, occlusion tests, body plethysmography, forced expiratory flow by rapid thoracoabdominal compression, sulfur hexafluoride (SF6 ) multiple breath washout (MBW), and capillary blood gas analysis. Infants were classified as wheezers or non-wheezers using predefined cut-off values for the duration of inspiratory and expiratory wheeze. RESULTS: Wheezing was detected in 72 (65%) infants, with 43 (39%) having inspiratory and 53 (48%) having expiratory wheezing. Endotracheal mechanical ventilation in the neonatal period for > 24 hr was associated with inspiratory wheeze (P = 0.009). Airway resistance was increased in both inspiratory (P = 0.02) and expiratory (P = 0.004) wheezers and correlated with the duration of expiratory wheeze (r = 0.394, P < 0.001). Expiratory wheezers showed a significant increase in respiratory resistance (P = 0.001), time constant (0.012), and functional residual capacity using SF6 MBW (P = 0.019). There was no association between wheezing and forced expiratory flow or blood gases. CONCLUSION: CORSA can help identify neonates and young infants with subclinical airway obstruction and may prove useful in the follow-up of high-risk infants.

The lung clearance index in young infants: impact of tidal volume and dead space.

Lung clearance index (LCI), measured by multiple breath washout (MBW), is one of the most frequently used measures of ventilation inhomogeneity. This study was designed to investigate the effect of lung volumes on LCI in young infants. The dependence of LCI on dead space volume (VD), tidal volume (VT) and functional residual capacity (FRC) was investigated by mathematical modeling and by MBW measurements using sulfur hexafluoride (SF6) as a tracer gas. MBW was performed in 150 infants, of median postmenstrual age 46.7 weeks, followed up after neonatal intensive care. Wheezing was assessed in 90 of these infants by computerized respiratory sound analysis during quiet sleep. The strongest correlation was observed between LCI and the volume ratios VT/FRC (Spearman rank order correlation coefficient Rs = 0.688, p < 0.001), VD/VT (Rs = 0.733, p < 0.001) and VD/FRC (Rs = 0.854, p < 0.001). LCI calculated from VD, VT, and FRC was linearly related to measured LCI with a coefficient of determination of 75%. There were no significant differences between wheezers and non-wheezers in postmenstrual age and body weight, but FRC was significantly increased (p < 0.001) and median (interquartile range) LCI significantly decreased (5.83 (5.45-6.51) versus (6.54 (6.03-7.22), p < 0.001) in wheezing compared to non-wheezing infants. Model calculations also showed that LCI was significantly reduced in wheezing infants (5.09 (4.79-5.62) versus 5.43 (5.08-5.82), p < 0.018), indicating that the reduction can be explained by differences in the lung volumes, not by improved ventilation homogeneity. In conclusion, the strong dependence of LCI on lung volumes in young infants can lead to misinterpretations regarding the homogeneity of alveolar ventilation.

Postnatal lung function in congenital cystic adenomatoid malformation of the lung.

BACKGROUND: Management of prenatally diagnosed but postnatal asymptomatic pulmonary lesions remains controversial. The aim of this study was to investigate the effect of congenital cystic adenomatoid malformation of the lung (CCAM) on postnatal lung function tests (LFT) and to elucidate whether LFTs help identify infants who would benefit from early surgery. METHODS: The LFTs were performed in 26 CCAM infants at a median (interquartile range) postmenstrual age of 42.4 (39.6 to 44.0) weeks and compared with LFT from 30 healthy controls. The LFT included the measurement of tidal breathing, functional residual capacity by body plethysmography, respiratory mechanics (respiratory compliance), and respiratory resistance by occlusion test and blood gas analysis. RESULTS: The CCAM infants showed a restrictive ventilation disorder with increased respiratory rates (p = 0.006) and marginally decreased tidal volumes (p = 0.043). Furthermore, respiratory compliance was significantly reduced as compared with controls (p < 0.001). No statistically significant differences were seen in the respiratory resistance, functional residual capacity, and capillary blood gases. Particularly in CCAM infants who had surgery in the first 2 years of life, a marked reduction of respiratory compliance (p < 0.001) was seen preoperatively. CONCLUSIONS: Congenital cystic adenomatoid malformation can cause restrictive ventilation disorders, which can be detected and monitored by postnatal LFT. Thus, LFT represents an additional tool to support the decision for or against surgical intervention.

Nasal high-frequency oscillation ventilation in neonates: a survey in five European countries.

UNLABELLED: Nasal high-frequency oscillation ventilation (nHFOV) is a non-invasive ventilation mode that applies an oscillatory pressure waveform to the airways using a nasal interface. nHFOV has been shown to facilitate carbon dioxide expiration, but little is known about its use in neonates. In a questionnaire-based survey, we assessed nHFOV use in neonatal intensive care units (NICUs) in Austria, Switzerland, Germany, the Netherlands, and Sweden. Questions included indications for nHFOV, equipment used, ventilator settings, and observed side effects. Of the clinical directors of 186 NICUs contacted, 172 (92 %) participated. Among those responding, 30/172 (17 %) used nHFOV, most frequently in premature infants <1500 g (27/30) for the indication nasal continuous positive airway pressure (nCPAP) failure (27/30). Binasal prongs (22/30) were the most common interfaces. The median (range) mean airway pressure when starting nHFOV was 8 (6-12) cm H2O, and the maximum mean airway pressure was 10 (7-18) cm H2O. The nHFOV frequency was 10 (6-13) Hz. Abdominal distension (11/30), upper airway obstruction due to secretions (8/30), and highly viscous secretions (7/30) were the most common nHFOV side effects. CONCLUSION: In a number of European NICUs, clinicians use nHFOV. The present survey identified differences in nHFOV equipment, indications, and settings. Controlled clinical trials are needed to investigate the efficacy and side effects of nHFOV in neonates.

Validation of computerized wheeze detection in young infants during the first months of life.

BACKGROUND: Several respiratory diseases are associated with specific respiratory sounds. In contrast to auscultation, computerized lung sound analysis is objective and can be performed continuously over an extended period. Moreover, audio recordings can be stored. Computerized lung sounds have rarely been assessed in neonates during the first year of life. This study was designed to determine and validate optimal cut-off values for computerized wheeze detection, based on the assessment by trained clinicians of stored records of lung sounds, in infants aged <1 year. METHODS: Lung sounds in 120 sleeping infants, of median (interquartile range) postmenstrual age of 51 (44.5-67.5) weeks, were recorded on 144 test occasions by an automatic wheeze detection device (PulmoTrack®). The records were retrospectively evaluated by three trained clinicians blinded to the results. Optimal cut-off values for the automatically determined relative durations of inspiratory and expiratory wheezing were determined by receiver operating curve analysis, and sensitivity and specificity were calculated. RESULTS: The optimal cut-off values for the automatically detected durations of inspiratory and expiratory wheezing were 2% and 3%, respectively. These cutoffs had a sensitivity and specificity of 85.7% and 80.7%, respectively, for inspiratory wheezing and 84.6% and 82.5%, respectively, for expiratory wheezing. Inter-observer reliability among the experts was moderate, with a Fleiss' Kappa (95% confidence interval) of 0.59 (0.57-0.62) for inspiratory and 0.54 (0.52 - 0.57) for expiratory wheezing. CONCLUSION: Computerized wheeze detection is feasible during the first year of life. This method is more objective and can be more readily standardized than subjective auscultation, providing quantitative and noninvasive information about the extent of wheezing.

Development of left ventricular longitudinal speckle tracking echocardiography in very low birth weight infants with and without bronchopulmonary dysplasia during the neonatal period.

OBJECTIVES: In preterm infants, postnatal myocardial adaptation may be complicated by bronchopulmonary dysplasia (BPD). We aimed to describe the development of left ventricular function by serial 2D, Doppler, and speckle tracking echocardiography (2D-STE) in infants with and without BPD during the neonatal period and compare these to anthropometric and conventional hemodynamic parameters. STUDY DESIGN: Prospective echocardiography on day of life (DOL) 1, 7, 14, and 28 in 119 preterm infants <1500 g birth weight of whom 36 developed BPD (need for oxygen supplementation at 36 weeks gestational age). Non-BPD and BPD infants differed significantly in median (IQR) gestational age (25.5(24-26.5) weeks vs. 29(27-30) weeks, p<0.001) and birth weight (661(552-871) g vs. 1100(890-1290) g, p<0.001). RESULTS: The intra- and inter-observer variability of the 2D-STE parameters measured did not depend on time of measurement, although there were significant differences in the reproducibility of the parameters. Low intra- and inter-observer variability was seen for longitudinal systolic strain and strain rate mid septum with a median CV (coefficient of variation) of <4.6%. Much higher CVs (>10%) were seen for the apical segment. While anthropometric parameters show rapid development during the first 4 weeks of life, the speckle tracking parameters did not differ statistically significantly during the neonatal period. Infants with and without BPD differed significantly (p<0.001) in the development of anthropometric parameters, conventional hemodynamic parameters except for heart rate, and 2D-STE parameters: global longitudinal systolic strain rate (GLSSR) and longitudinal systolic strain for the mid left wall (LSSR). The largest differences were seen at DOL 1 and 7 in GLSSR (p<0.001) and in LSSR (p<0.01). CONCLUSIONS: Reproducible 2D-STE measurements are possible in preterm infants <1500 g. Cardiac deformation reveals early (DOL 1 and 7) ventricular changes (GLSSR and LSSR) in very low birth weight infants who develop BPD.

Effect of intubation and mechanical ventilation on exhaled nitric oxide in preterm infants with and without bronchopulmonary dysplasia measured at a median postmenstrual age of 49 weeks.

BACKGROUND: Exhaled nitric oxide (eNO) is a marker of established airway inflammation in adults and children, but conflicting results have been reported in preterm infants when postnatal eNO is measured during tidal breathing. This study investigated the extent to which intubation and mechanical ventilation (MV) affect eNO and NO production (V'NO) in preterm infants with and without bronchopulmonary dysplasia (BPD). PATIENTS AND METHODS: A total of 176 very low birth weight (VLBW) infants (birth weight <1500 g), including 74 (42%) with and 102 (58%) without BPD, were examined at a median postmenstrual age of 49 weeks. Of the 176 infants, 84 (48%) did not require MV, 47 (27%) required MV for <7 days and 45 (26%) required MV for ≥7 days. Exhaled NO and tidal breathing parameters were measured in sleeping infants during tidal breathing, respiratory mechanics were assessed by occlusion tests, and arterialized capillary blood gas was analyzed. RESULTS: eNO was significantly correlated with tidal breathing parameters, while V'NO was correlated with growth parameters, including age and body length (p < 0.001 each). Infants who were intubated and received MV for <7 days had significantly lower eNO (p < 0.01) and V'NO (p < 0.01) than non-ventilated infants. In contrast, eNO and V'NO did not differ significantly in non-ventilated infants and those receiving MV for ≥7 days. Multivariate analysis showed that independent on the duration of MV eNO (p = 0.003) and V'NO (p = 0.018) were significantly increased in BPD infants comparable with the effects of intubation and MV on eNO (p = 0.002) and V'NO (p = 0.017). CONCLUSIONS: Preterm infants with BPD show only weak postnatal increases in eNO and V'NO, but these changes may be obscured by the distinct influences of breathing pattern and invasive respiratory support. This limits the diagnostic value of postnatal eNO measurements in the follow-up of BPD infants.

How ABBA may help improve neonatal resuscitation training: auditory prompts to enable coordination of manual inflations and chest compressions.

AIM: Resuscitation guidelines recommend 90 chest compressions (CCs) and 30 inflations (INFs) per minute for neonatal cardiopulmonary resuscitation (nCPR). We hypothesised that auditory prompts would help coordinate these actions. Our aim was to investigate the effect of musical prompts during nCPR training on adherence to recommended CC and INF rates and on the quality of delivered INFs. METHODS: A simulation study was conducted employing 30 experienced neonatal staff, a respiratory function monitor and a neonatal manikin. The effects of five different auditory prompts on adherence to recommended rates of CC and INF were tested against baseline (no music). The five auditory prompts (popular musical tunes) were investigated in random order. Quality of INFs was assessed by comparing the peak inflation pressures (PIP), positive end-expiratory pressures (PEEP), percentage mask leak and tidal volumes (VT). RESULTS: Mean baseline rates at which CCs and INFs were delivered were 80 (SD 6) per minute and 28 (SD 2) per minute, respectively. Listening to auditory prompts had varying effects on CC and INF delivery rates. For CCs, a significant difference to baseline was found only when participants listened to ABBA's 'SOS', with 86 (SD 7) per minute (P = 0.04). For INFs, we found a statistically significant improvement to baseline rate only for 'SOS', with 29 (SD 2) per minute (P = 0.04), and there was no significant difference in INF quality among the auditory prompts. CONCLUSIONS: Musical prompts can help with adherence to recommended CC and INF rates but do not improve the quality of INFs during nCPR training. The lasting effect of auditory prompts as musical mnemonics on nCPR performance in vivo needs to be established.

Dead space reduction by Kolobow's endotracheal tube does not justify the waiving of volume monitoring in small, ventilated lungs.

In ventilated preterm infants the flow sensor contributes significantly to the total apparatus dead space, which may impair gas exchange. The aim of the study was to quantify to which extent a dead space reduced Kolobow tube (KB) without flow sensor improves the gas exchange compared with a conventional ventilator circuit with flow sensor [Babylog 8000 (BL)]. In a cross-over trial in 14 tracheotomized, surfactant-depleted (saline lavage) and mechanically ventilated newborn piglets (age <12 h; body weight 705-1200 g) BL and KB was applied alternately for 15 min and blood gases were recorded. The inner diameter of the endotracheal tube was 3.6 mm and the apparatus dead space of BL and KB including the endotracheal tube were 3.0 and 1.34 mL. Despite a 50 % apparatus dead space reduction with KB compared to BL statistically significant improvements were only observed for body weights <900 g. In this weight group median paCO2 was decreased by 5 mmHg (p < 0.01), whereas the improvement decreased with decreasing baseline paCO2. Furthermore, median paO2 was increased by 4 mmHg (p < 0.05) and O2 saturation was increased by 2.5 % (p < 0.05). No significant changes were seen in the circulatory parameters. In very small, ventilated lungs the use of KB improved the gas exchange; however, the improvement was moderate and does not justify the waiving of volume monitoring.