Toy story: A cross-sectional survey of toy populations in tertiary neonatal units.

Thousands of babies are given toys for their zeroth birthday … But what happens if that baby is admitted to neonatal intensive care? In a global first, we describe the population of toys found in incubators on neonatal intensive care unit.

Predictors of outcome of prematurely born infants with pulmonary interstitial emphysema.

AIM: To determine how oxygenation, ventilation efficiency and tidal volume requirements changed with the development of pulmonary interstitial emphysema (PIE) and whether in affected patients a composite gas exchange index predicted death or bronchopulmonary dysplasia (BPD). METHODS: Infants who developed PIE from 2010 to 2016 were identified. The oxygenation index (OI), ventilation efficiency index (VEI), ventilation to perfusion ratio and inspiratory tidal volume were calculated before radiological evidence of PIE (pre-PIE) and at the worst PIE radiographic appearance (PIE-worst). RESULTS: Thirty infants, median (IQR) gestational age of 24.6 (24.3-26.7) weeks were assessed. Their age at pre-PIE was 11 (6-19) days and 23 (13-42) days at PIE-worst. Compared to pre-PIE, at PIE-worst, the OI was higher [14.5 (10.7-19.2) vs 4.8 (3.1-6.1), respectively, p < 0.001], VEI was lower [0.01 (0.01-0.11) vs 0.16 (0.13-0.19), respectively, p < 0.001], ventilation to perfusion ratio was lower [0.15 (0.11-0.40) vs 0.26 (0.20-0.37), p = 0.033] and tidal volume was higher [9.9 (7.2-13.1) vs 6.4 (5.5-6.8) mL/kg, p = 0.007]. An OI >11.4 at PIE-worst predicted death or BPD with 80% sensitivity and 100% specificity. CONCLUSION: Development of PIE was associated with poorer oxygenation and ventilation efficiency despite increased tidal volumes. The OI at PIE-worst predicted death or BPD.

In vitro assessment of the effect of proportional assist ventilation on the work of breathing.

UNLABELLED: During proportional assist ventilation, elastic and resistive unloading can be delivered to reduce the work of breathing (WOB). Our aim was to determine the effects of different levels of elastic and resistive unloading on the WOB in lung models designed to mimic certain neonatal respiratory disorders. Two dynamic lung models were used, one with a compliance of 0.4 ml/cm H2O to mimic an infant with respiratory distress syndrome and one with a resistance of 300 cm H2O/l/s to mimic an infant with bronchopulmonary dypslasia. Pressure volume curves were constructed at each unloading level. Elastic unloading in the low compliance model was highly effective in reducing the WOB measured in the lung model; the effective compliance increased from 0.4 ml/cm H2O at baseline to 4.1 ml/cm H2O at maximum possible elastic unloading (2.0 cm H2O/ml). Maximum possible resistive unloading (200 cm H2O/l/s) in the high-resistance model only reduced the effective resistance from 300 to 204 cm H2O/l/s. At maximum resistive unloading, oscillations appeared in the airway pressure waveform. CONCLUSION: Our results suggest that elastic unloading will be helpful in respiratory conditions characterised by a low compliance, but resistive unloading as currently delivered is unlikely to be of major clinical benefit. WHAT IS KNOWN: • During PAV, the ventilator can provide elastic and resistive unloading. What is New: • Elastic unloading was highly effective in reducing the work of breathing. • Maximum resistive unloading only partially reduced the effective resistance.

Volume-targeted versus pressure-limited ventilation in infants born at or near term.

Our aims were to determine whether volume-targeted ventilation (VTV) or pressure-limited ventilation (PLV) reduced the time to successful extubation and if any difference was explained by a lower work of breathing (WOB), better respiratory muscle strength or less thoracoabdominal asynchrony (TAA) and associated with fewer hypocarbic episodes. Infants born at ≥34 weeks of gestational age were randomised to VTV or PLV. The WOB was assessed by the transdiaphragmatic pressure time product, respiratory muscle strength by the maximum inflation (Pimax) and expiratory (Pemax) pressures and TAA assessed using uncalibrated respiratory inductance plethysmography. Forty infants, median gestational age of 39 (range 34-42) weeks, were recruited. The time to successful extubation did not differ between the two groups (median 25, range 2.5-312 h (VTV) versus 33.5, 1.312 h (PLV)) (p = 0.461). There were no significant differences between the groups with regard to the WOB, respiratory muscle strength or the TAA results. The median number of hypocarbic episodes was 1.5 (range 0-8) in the VTV group versus 4 (range 1-13) in the PLV group (p = 0.005). CONCLUSION: In infants born at or near term, VTV compared to PLV did not reduce the time to successful extubation but was associated with significantly fewer hypocarbic episodes. WHAT IS KNOWN: In prematurely born infants, volume-targeted ventilation (VTV) compared to pressure-limited ventilation (PLV) reduces bronchopulmonary dysplasia or death. In addition, VTV is associated in prematurely born infants with lower incidences of pneumothorax, intraventricular haemorrhage and hypocarbic episodes. WHAT IS NEW: Despite a high morbidity, few studies have investigated optimum ventilation strategies for infants born at or near term. In a RCT, we have demonstrated VTV versus PLV in infants ≥34 weeks gestation was associated with significantly fewer hypocarbic episodes.

Randomised trial of volume-targeted ventilation versus pressure-limited ventilation in acute respiratory failure in prematurely born infants.

BACKGROUND: During volume-targeted ventilation (VTV), a constant volume is delivered with each ventilator inflation. OBJECTIVES: To determine whether VTV compared to pressure-limited ventilation (PLV) reduced the time to reach weaning criteria in prematurely born infants with acute respiratory distress, and if any difference was explained by better respiratory muscle strength and/or a lower work of breathing (WOB). METHODS: Infants of <34 weeks of gestational age ventilated for <24 h in the first week after birth were randomised to receive either VTV or PLV. The primary outcome was the time to achieve pre-specified weaning criteria. Respiratory muscle strength was assessed by the measurement of the maximum inflation and expiratory pressures, and the WOB assessed by the transdiaphragmatic pressure time product. Other outcomes reported are the duration of ventilation, occurrence of patent ductus arteriosus, pneumothorax, intraventricular haemorrhage, periventricular leukomalacia and episodes of hypocarbia. RESULTS: Forty infants, median gestational age 27 (range 23-33) weeks, were recruited. The time taken to achieve weaning criteria was similar in the two groups [median 14 h (VTV) vs. 23 h (PLV)]. There were no significant differences between the groups with regard to respiratory muscle strength, WOB or other outcomes, except that fewer of the VTV compared to the PLV group had episodes of hypocarbia (8 vs. 19; p < 0.001). CONCLUSION: In prematurely born infants with acute respiratory failure, use of VTV did not reduce the time to reach weaning criteria, but was associated with a reduction in episodes of hypocarbia.

Respiratory support practices in infants born at term in the United Kingdom.

Infants born at term requiring mechanical ventilation suffer significant mortality and morbidity, yet few studies have tried to identify the optimum respiratory support for such infants. We, therefore, hypothesised that practice would vary, particularly between different levels of neonatal care provision. The lead clinicians of all 212 UK neonatal units were asked to complete an electronic web-based survey regarding respiratory support practices for term-born infants. Survey questions included the level of neonatal care provided, number of term-born infants ventilated per annum, initial and rescue ventilation modes and whether surfactant or inhaled nitric oxide (NO) were used. The overall response rate was 82 %. A greater proportion of neonatal intensive care units (NICUs) compared to local neonatal units (LNUs) stated that they used volume-targeting, particularly for infants with RDS (p = 0.0006) or congenital pneumonia (p = 0.0005). High-frequency oscillatory ventilation was stated as initial mode by a greater proportion of NICUs compared to LNUs and special care units (SCUs), particularly for respiratory distress syndrome (p < 0.0001) or persistent pulmonary hypertension of the newborn (p < 0.001). Continuous mandatory ventilation was stated to be the rescue mode by a greater proportion of LNUs/SCUs compared to NICUs (p < 0.0001). Surfactant was stated to be most commonly given for respiratory distress syndrome (79 % of units) and MAS (61 % of units); surfactant use was lowest in SCUs (p < 0.0001); inhaled NO was infrequently used by LNUs and SCUs. Conclusions There was considerable variation in respiratory support practices for term-born infants, particularly between different levels of neonatal care provision.

CPAP review.

Continuous positive airway pressure (CPAP) is widely used in neonatal units both as a primary mode of respiratory support and following extubation from mechanical ventilation. In this review, the evidence for CPAP use particularly in prematurely born infants is considered. Studies comparing methods of CPAP generation have yielded conflicting results, but meta-analysis of randomised trials has demonstrated that delivering CPAP via short nasal prongs is most effective in preventing re-intubation. At present, there is insufficient evidence to establish the safety or efficacy of high flow nasal cannulae for prematurely born infants. Observational studies highlighted that early CPAP use rather than intubation and ventilation was associated with a lower incidence of bronchopulmonary dysplasia (BPD), but this has not been confirmed in three large randomised trials. Meta-analysis of the results of randomised trials has demonstrated that use of CPAP reduces extubation failure, particularly if a CPAP level of 5 cm H2O or more is used. Nasal injury can occur and is related to the length of time CPAP is used; weaning CPAP by pressure rather than by "time-cycling" reduces the weaning time and may reduce BPD. In conclusion, further studies are required to identify the optimum mode of CPAP generation and it is important that prematurely born infants are weaned from CPAP as soon as possible.

Volume-targeted ventilation in infants born at or near term.

OBJECTIVES: To determine the impact of different volume-targeted (VT) levels during volume-targeted ventilation (VTV) on the work of breathing (WOB) of infants born at or near term and to investigate whether a level of VT reduced the WOB below that experienced on respiratory support without VT. DESIGN: Prospective crossover study. PATIENTS: Sixteen infants, median gestational age of 38 (range 34-41) weeks, birth weight of 3.1 (range 1.5-4.1) kg and postnatal age of 5 (range 2-17) days were studied. The infants were receiving time-cycled, pressure-limited ventilation in a continuous mandatory or in a triggered mode. INTERVENTIONS: The infants were studied first without VT (baseline) and then at VT levels of 4, 5 and 6 ml/kg delivered in a random order. After each VT level, the infants were returned to baseline. MAIN OUTCOME MEASURE: The WOB was assessed by measuring the transdiaphragmatic pressure-time product (PTPdi). RESULTS: One infant became apnoeic at VT of 6 ml/kg. At a VT level of 4 ml/kg, four infants were making such vigorous respiratory efforts that no inflations were delivered. The median PTPdi was higher at a VT level of 4 ml/kg than at 5 ml/kg (p<0.01) or 6 ml/kg (p<0.001). Only at a VT level of 6 ml/kg was the median PTPdi lower than that at baseline (p<0.01). CONCLUSION: Low VT levels (4 ml/kg) during VTV increase the WOB in ventilated infants born at term or near term. The results suggest that a VT level of 6 ml/kg could be used to reduce the WOB.

Neonatal ventilatory techniques - which are best for infants born at term?

Few studies have examined ventilatory modes exclusively in infants born at term. Synchronous intermittent mandatory ventilation (SIMV) compared to intermittent mandatory ventilation (IMV) is associated with a shorter duration of ventilation. The limited data on pressure support, volume targeted ventilation and neurally adjusted ventilatory assist demonstrate only short term benefits in term born infants. Favourable results of high-frequency oscillatory ventilation (HFOV) in infants with severe respiratory failure were not confirmed in the two randomised trials. Nitric oxide (NO) in term born infants, except in those with congenital diaphragmatic hernia (CDH), reduces the combined outcome of death and requirement for extracorporeal membrane oxygenation (ECMO). In infants with severe refractory hypoxaemic respiratory failure, ECMO, except in infants with CDH, reduced mortality and the combined outcome of death and severe disability at long-term follow-up. Randomised studies with long term outcomes are required to determine the optimum modes of ventilation in term born infants.