Effect of nasal continuous and biphasic positive airway pressure on lung volume in preterm infants

Non-invasive versus invasive respiratory support in preterm infants

Respiratory insufficiency is almost ubiquitous in infants born preterm, with its incidence increasing with lower gestational age. A wide range of respiratory support management strategies are available for these infants, separable into non-invasive and invasive forms of respiratory support. Here we review the history and evolution of respiratory care for the preterm infant and then examine evidence that has emerged to support a non-invasive approach to respiratory management where able. Continuous positive airway pressure (CPAP) is the non-invasive respiratory support mode currently with the most evidence for benefit. CPAP can be delivered safely and effectively and can commence in the delivery room. Particularly in early life, time spent on non-invasive respiratory support, avoiding intubation and mechanical ventilation, affords benefit for the preterm infant by virtue of a lessening of lung injury and hence a reduction in incidence of bronchopulmonary dysplasia. In recent years, enthusiasm for application of non-invasive support has been further bolstered by new techniques for administration of exogenous surfactant. Methods of less invasive surfactant delivery, in particular with a thin catheter, have allowed neonatologists to administer surfactant without resort to endotracheal intubation. The benefits of this approach appear to be sustained, even in those infants subsequently requiring mechanical ventilation. This cements the notion that any reduction in exposure to mechanical ventilation leads to alleviation of injury to the vulnerable preterm lung, with a long-lasting effect. Despite the clear advantages of non-invasive respiratory support, there will continue to be a role for intubation and mechanical ventilation in some preterm infants, particularly for those born <25 weeks' gestation. It is currently unclear what role early non-invasive support has in this special population, with more studies required.

Continuous Positive Airway Pressure versus Nasal Intermittent Positive Pressure Ventilation in Preterm Neonates: What if Mean Airway Pressures were Equivalent?

Respiratory support for preterm neonates in modern neonatal intensive care units is predominantly with the use of noninvasive interfaces. Continuous positive airway pressure (CPAP) and nasal intermittent positive pressure ventilation (NIPPV) are the prototypical and most commonly utilized forms of noninvasive respiratory support, and each has unique gas flow characteristics. In meta-analyses of clinical trials till date, NIPPV has been shown to likely reduce respiratory failure and need for intubation compared to CPAP. However, a significant limitation of the included studies has been the higher mean airway pressures used during NIPPV. Thus, it is unclear to what extent any benefits seen with NIPPV are due to the cyclic pressure application versus the higher mean airway pressures. In this review, we elaborate on these limitations and summarize the available evidence comparing NIPPV and CPAP at equivalent mean airway pressures. Finally, we call for further studies comparing noninvasive respiratory support modes at equal mean airway pressures. KEY POINTS: · Most current literature on CPAP vs. NIPPV in preterm neonates is confounded by use of higher mean airway pressures during NIPPV.. · In this review, we summarize existing evidence on CPAP vs. NIPPV at equivalent mean airway pressures.. · We call for future research on noninvasive support modes to account for mean airway pressures..

Bubble CPAP respiratory support devices for infants in low-resource settings

Approximately 46% of the 5.2 million annual under-5 deaths derive from neonatal conditions commonly associated with hypoxemia or acute respiratory distress. It has been estimated that 98% of these deaths occur in low- and middle-income countries (LMICs). Effective implementation of noninvasive respiratory support at all levels of healthcare could significantly reduce neonatal mortality. Several factors limit the widespread and effective implementation of noninvasive respiratory support in LMICs, including inadequate infrastructure, lack of proper instrumentation, shortage of skilled staff, costly disposables, and difficulties in the supply of consumables and spare parts. The aim of this state-of-the-art paper is to provide a detailed evaluation of the commercially available devices providing noninvasive respiratory support in LMICs, focusing on bubblecontinuous positive airway pressure (bCPAP). bCPAP might be administrated using a variety of different commercial devices, including devices specifically designed for LMICs, as well as using self-made systems. We described all the equipment required for safe and effective implementation of bCPAP, including air and oxygen sourced, pressure-reducing valves and flowmeters, air-oxygen blending systems, humidifiers, respiratory support devices, patient circuits, and airway interfaces. Specifically, we critically evaluated the advantages and disadvantages of various existing solutions within the context of low-resource settings.

Different Settings of Nonsynchronized Bilevel Nasal Continuous Positive Airway Pressure and Respiratory Function in Preterm Infants: A Pilot Study

OBJECTIVE

With this study, we evaluated the short-term effects of different modes and settings of noninvasive respiratory support on gas exchange, breathing parameters, and thoracoabdominal synchrony in preterm infants in the acute phase of moderate respiratory distress syndrome.

STUDY DESIGN

A feasibility crossover trial was conducted in neonates < 32 weeks' gestation on nasal continuous positive airway pressure (n-CPAP) or bilevel n-CPAP. Infants were delivered the following settings in consecutive order for 10 minutes each: • n-CPAP (5 cm H₂O) • bilevel n-CPAP 1 (Pres low = 5 cm H₂O, Pres high = 7 cm H₂O, T-high = 1 second, rate = 30/min) • n-CPAP (5 cm H₂O) • bilevel n-CPAP 2 (Pres low = 5 cm H₂O, Pres high = 7 cm H₂O, T-high = 2 second, rate = 15/min) • n-CPAP (5 cm H₂O). During each phase, physiologic parameters were recorded; the thoracoabdominal synchrony expressed by the phase angle (Φ) and other respiratory patterns were monitored by noncalibrated respiratory inductance plethysmography.

RESULTS

Fourteen preterm infants were analyzed. The mean CPAP level was significantly lower in the n-CPAP period compared with bilevel n-CPAP 1 and 2 (p = 0.03). Higher values were achieved with bilevel n-CPAP 2 (6.2 ± 0.6 vs. 5.7 ± 0.5 cm H₂O, respectively; p < 0.05). No statistical difference in the Φ was detected, nor between the three settings.

CONCLUSION

Our study did not show any superiority of bilevel n-CPAP over n-CPAP. However, nonsynchronized bilevel n-CPAP might be helpful when additional pressure is needed.

KEY POINTS

· There is currently a high degree of uncertainty about the superiority of one modality and setting of noninvasive respiratory over another.. · Our study confirmed that non-synchronized bilevel n-CPAP might be helpful when additional pressure is needed for recruitment.. · A T-high of 1 second could possibly be better tolerated in this population, but further research is needed..

Higher CPAP levels improve functional residual capacity at birth in preterm rabbits

BACKGROUND

Preterm infants are commonly supported with 4-8 cm H₂O continuous positive airway pressures (CPAP), although higher CPAP levels may improve functional residual capacity (FRC).

METHODS

Preterm rabbits delivered at 29/32 days (~26-28 weeks human) gestation received 0, 5, 8, 12, 15 cm H₂O of CPAP or variable CPAP of 15 to 5 or 15 to 8 cm H₂O (decreasing ~2 cm H₂O/min) for up to 10 min after birth.

RESULTS

FRC was lower in the 0 (6.8 (1.0-11.2) mL/kg) and 5 (10.1 (1.1-16.8) mL/kg) compared to the 15 (18.8 (10.9-22.4) mL/kg) cm H₂O groups (p = 0.003). Fewer kittens achieved FRC > 15 mL/kg in the 0 (20%), compared to 8 (36%), 12 (60%) and 15 (73%) cm H₂O groups (p = 0.008). While breathing rates were not different (p = 0.096), apnoea tended to occur more often with CPAP < 8 cm H₂O (p = 0.185). CPAP belly and lung bulging rates were similar whereas pneumothoraces were rare. Lowering CPAP from 15 to 5, but not 15 to 8 cm H₂O, decreased FRC and breathing rates.

CONCLUSION

In all, 15 cm H₂O of CPAP improved lung aeration and reduced apnoea, but did not increase the risk of lung over-expansion, pneumothorax or CPAP belly immediately after birth. FRC and breathing rates were maintained when CPAP was decreased to 8 cm H₂O.

IMPACT

Although preterm infants are commonly supported with 4-8 cm H₂O CPAP at birth, preclinical studies have shown that higher PEEP levels improve lung aeration. In this study, CPAP levels of 15 cm H₂O improved lung aeration and reduced apnoea in preterm rabbit kittens immediately after birth. In all, 15 cm H₂O CPAP did not increase the risk of lung over-expansion (indicated by bulging between the ribs), pneumothorax, or CPAP belly. These results can be used when designing future studies on CPAP strategies for preterm infants in the delivery room.

Novel Ventilation Strategies to Reduce Adverse Pulmonary Outcomes

Extremely preterm infants who must suddenly support their own gas exchange with lungs that are incompletely developed and lacking adequate amount of surfactant and antioxidant defenses are susceptible to lung injury. The decades-long quest to prevent bronchopulmonary dysplasia has had limited success, in part because of increasing survival of more immature infants. The process must begin in the delivery room with gentle assistance in establishing and maintaining adequate lung aeration, followed by noninvasive support and less invasive surfactant administration. Various modalities of invasive and noninvasive support have been used with varying degree of effect and are reviewed in this article.

High-frequency ventilation in preterm infants and neonates

High-frequency ventilation (HFV) has been used as a respiratory support mode for neonates for over 30 years. HFV is characterized by delivering tidal volumes close to or less than the anatomical dead space. Both animal and clinical studies have shown that HFV can effectively restore lung function, and potentially limit ventilator-induced lung injury, which is considered an important risk factor for developing bronchopulmonary dysplasia (BPD). Knowledge of how HFV works, how it influences cardiorespiratory physiology, and how to apply it in daily clinical practice has proven to be essential for its optimal and safe use. We will present important aspects of gas exchange, lung-protective concepts, clinical use, and possible adverse effects of HFV. We also discuss the study results on the use of HFV in respiratory distress syndrome in preterm infants and respiratory failure in term neonates. IMPACT: Knowledge of how HFV works, how it influences cardiorespiratory physiology, and how to apply it in daily clinical practice has proven to be essential for its optimal and safe use. Therefore, we present important aspects of gas exchange, lung-protective concepts, clinical use, and possible adverse effects of HFV. The use of HFV in daily clinical practice in lung recruitment, determination of the optimal continuous distending pressure and frequency, and typical side effects of HFV are discussed. We also present study results on the use of HFV in respiratory distress syndrome in preterm infants and respiratory failure in term neonates.

Extubation generates lung volume inhomogeneity in preterm infants

OBJECTIVE

To evaluate the feasibility of electrical impedance tomography (EIT) to describe the regional tidal ventilation (V_T) and change in end-expiratory lung volume (EELV) patterns in preterm infants during the process of extubation from invasive to non-invasive respiratory support.

DESIGN

Prospective observational study.

SETTING

Single-centre tertiary neonatal intensive care unit.

PATIENTS

Preterm infants born <32 weeks' gestation who were being extubated to nasal continuous positive airway pressure as per clinician discretion.

INTERVENTIONS

EIT measurements were taken in supine infants during elective extubation from synchronised positive pressure ventilation (SIPPV) before extubation, during and then at 2 and 20 min after commencing nasal continuous positive applied pressure (nCPAP). Extubation and pressure settings were determined by clinicians.

MAIN OUTCOME MEASURES

Global and regional ΔEELV and ΔV_T, heart rate, respiratory rate and oxygen saturation were measured throughout.

RESULTS

Thirty infants of median (range) 2 (1, 21) days were extubated to a median (range) CPAP 7 (6, 8) cm H₂O. SpO₂/FiO₂ ratio was a mean (95% CI) 50 (35, 65) lower 20 min after nCPAP compared with SIPPV. EELV was lower at all points after extubation compared with SIPPV, and EELV loss was primarily in the ventral lung (p=0.04). V_T was increased immediately after extubation, especially in the central and ventral regions of the lung, but the application of nCPAP returned V_T to pre-extubation patterns.

CONCLUSIONS

EIT was able to describe the complex lung conditions occurring during extubation to nCPAP, specifically lung volume loss and greater use of the dorsal lung. EIT may have a role in guiding peri-extubation respiratory support.

Patient-Ventilator Synchrony in Extremely Premature Neonates during Non-Invasive Neurally Adjusted Ventilatory Assist or Synchronized Intermittent Positive Airway Pressure: A Randomized Crossover Pilot Trial

INTRODUCTION

Synchronization of non-invasive ventilation is challenging in extremely premature infants. We compared patient-ventilator synchrony between non-invasive neurally adjusted ventilatory assist (NIV-NAVA) using transdiaphragmatic (Edi) catheter and synchronized intermittent positive airway pressure (SiPAP) using an abdominal trigger.

METHODS

This study was a monocentric, randomized, crossover trial in premature infants born before 28 weeks of gestation, aged 3 days or more, and below 32 weeks postmenstrual age. NIV-NAVA and SiPAP were applied in a random order for 2 h with analysis of data from the second hour. The primary outcome was the asynchrony index.

RESULTS

Fourteen patients were included (median [IQR] gestational age at birth 25.6 (25.3-26.4) weeks, median [IQR] birth weight 755 [680-824] g, median [IQR] postnatal age 26.5 [19.8-33.8] days). The median (IQR) asynchrony index was significantly lower in NIV-NAVA versus SiPAP (49.9% [44.1-52.6] vs. 85.8% [74.2-90.9], p < 0.001). Ineffective efforts and auto-triggering were significantly less frequent in NIV-NAVA versus SiPAP (3.0% vs. 32.0% p < 0.001 and 10.0% vs. 26.6%, p = 0.004, respectively). Double triggering was significantly less frequent in SiPAP versus NIV-NAVA (0.0% vs. 9.0%, p < 0.001). No significant difference was observed for premature cycling and late cycling. Peak Edi and swing Edi were significantly lower in NIV-NAVA as compared to SiPAP (7.7 [6.1-9.9] vs. 11.0 [6.7-14.5] μV, p = 0.006; 5.4 [4.2-7.6] vs. 7.6 [4.3-10.8] μV, p = 0.007, respectively). No significant difference was observed between NIV-NAVA and SiPAP for heart rate, respiratory rate, COMFORTneo scores, apnoea, desaturations, or bradycardias.

DISCUSSION/CONCLUSION

NIV-NAVA markedly improves patient-ventilator synchrony as compared to SiPAP in extremely premature infants.

Comparison of Nasal CPAP versus Bi-level CPAP in Transient Tachypnea of the Newborn: A Randomized Trial

OBJECTIVE

The optimal noninvasive ventilation (NIV) modality in the treatment of transient tachypnea of the newborn (TTN) is still unknown. The aim of this study was to compare nasal continuous positive airway pressure (NCPAP) versus bi-level CPAP in the treatment of TTN.

STUDY DESIGN

This was a prospective randomized study that was conducted in a tertiary level neonatal intensive care unit of Zekai Tahir Burak Women's Health Education and Research Hospital during the 1-year period between April 2017 and March 2018. The study included infants at ≥34 gestational weeks and birth weight ≥2,000 g who were diagnosed with TTN. The patients were randomized to either NCPAP or bi-level CPAP groups as initial respiratory support. The primary outcome was the rate of NIV failure.

RESULTS

A total of 151 infants were incorporated into the study. The intubation rate was significantly higher in the NCPAP group (15/75) compared with the bi-level CPAP group (6/76) (p = 0.032). There was a significant decrease in the level of pCO₂ at the 12 (60.7 ± 6.7 vs. 66.3 ± 8.8, p = 0.017) and 24 (50 ± 8 vs. 53 ± 10, p = 0.028) hours of NIV in the bi-level CPAP group compared with the NCPAP group. Duration of NIV, total respiratory support, hospital stay, and the incidence of pneumothorax were similar between the groups.

CONCLUSION

Bi-level CPAP reduced the rate of NIV failure and pCO₂ levels at the 12 and 24 hours in late preterm and term infants with a diagnosis of TTN.

KEY POINTS

· Bi-level CPAP seems to be a safe and effective method in TTN.. · Bi-level CPAP may reduce the rate of NIV failure in late preterm and term infants with TTN.. · Future studies are warranted to answer the question whether bi-level CPAP might be used as a standard treatment in babies with TTN..

Nasal Intermittent Positive Pressure Ventilation for Neonatal Respiratory Distress Syndrome

Nasal or noninvaisve intermittent positive pressure ventilation (NIPPV) refers to well-established noninvasive respiratory support strategies combining a continuous distending pressure with intermittent pressure increases. Uncertainty remains regarding the benefits provided by the various devices and techniques used to generate NIPPV. Our included meta-analyses of trials comparing NIPPV with continuous positive airway pressure (CPAP) in preterm infants demonstrate that both primary and postextubation NIPPV are superior to CPAP to prevent respiratory failure leading to additional ventilatory support. This short-term benefit is associated with a reduction in bronchopulmonary dysplasia, but not with mortality. Benefits are greatest when ventilator-generated, synchronized NIPPV is used.

Nasal continuous positive airway pressure levels for the prevention of morbidity and mortality in preterm infants

BACKGROUND

Preterm infants are at risk of lung atelectasis due to various anatomical and physiological immaturities, placing them at high risk of respiratory failure and associated harms. Nasal continuous positive airway pressure (CPAP) is a positive pressure applied to the airways via the nares. It helps prevent atelectasis and supports adequate gas exchange in spontaneously breathing infants. Nasal CPAP is used in the care of preterm infants around the world. Despite its common use, the appropriate pressure levels to apply during nasal CPAP use remain uncertain.

OBJECTIVES

To assess the effects of 'low' (≤ 5 cm H₂O) versus 'moderate-high' (> 5 cm H₂O) initial nasal CPAP pressure levels in preterm infants receiving CPAP either: 1) for initial respiratory support after birth and neonatal resuscitation or 2) following mechanical ventilation and endotracheal extubation.

SEARCH METHODS

We ran a comprehensive search on 6 November 2020 in the following databases: CENTRAL via CRS Web and MEDLINE via Ovid. We also searched clinical trials databases and the reference lists of retrieved articles for randomized controlled trials (RCTs) and quasi-randomized trials.

SELECTION CRITERIA

We included RCTs, quasi-RCTs, cluster-RCTs and cross-over RCTs randomizing preterm infants of gestational age < 37 weeks or birth weight < 2500 grams within the first 28 days of life to different nasal CPAP levels.

DATA COLLECTION AND ANALYSIS

We used the standard methods of Cochrane Neonatal to collect and analyze data. We used the GRADE approach to assess the certainty of the evidence for the prespecified primary outcomes.

MAIN RESULTS

Eleven trials met inclusion criteria of the review. Four trials were parallel-group RCTs reporting our prespecified primary or secondary outcomes. Two trials randomized 316 infants to low versus moderate-high nasal CPAP for initial respiratory support, and two trials randomized 117 infants to low versus moderate-high nasal CPAP following endotracheal extubation. The remaining seven studies were cross-over trials reporting short-term physiological outcomes. The most common potential sources of bias were absent or unclear blinding of personnel and assessors and uncertain selective reporting. Nasal CPAP for initial respiratory support after birth and neonatal resuscitation None of the six primary outcomes prespecified for inclusion in the summary of findings was eligible for meta-analysis. No trials reported on moderate-severe neurodevelopmental impairment at 18 to 26 months. The remaining five outcomes were reported in a single trial. On the basis of this trial, we are uncertain whether low or moderate-high nasal CPAP levels improve the outcomes of: death or bronchopulmonary dysplasia (BPD) at 36 weeks' postmenstrual age (PMA) (risk ratio (RR) 1.02, 95% confidence interval (CI) 0.56 to 1.85; 1 trial, 271 participants); mortality by hospital discharge (RR 1.04, 95% CI 0.51 to 2.12; 1 trial, 271 participants); BPD at 28 days of age (RR 1.10, 95% CI 0.56 to 2.17; 1 trial, 271 participants); BPD at 36 weeks' PMA (RR 0.80, 95% CI 0.25 to 2.57; 1 trial, 271 participants), and treatment failure or need for mechanical ventilation (RR 1.00, 95% CI 0.63 to 1.57; 1 trial, 271 participants). We assessed the certainty of the evidence as very low for all five outcomes due to risk of bias, a lack of consistency across multiple studies, and imprecise effect estimates. Nasal CPAP following mechanical ventilation and endotracheal extubation One of the six primary outcomes prespecified for inclusion in the summary of findings was eligible for meta-analysis. On the basis of these data, we are uncertain whether low or moderate-high nasal CPAP levels improve the outcome of treatment failure or need for mechanical ventilation (RR 1.52, 95% CI 0.92 to 2.50; 2 trials, 117 participants; I² = 17%; risk difference 0.15, 95% CI -0.02 to 0.32; number needed to treat for an additional beneficial outcome 7, 95% CI -50 to 3). We assessed the certainty of the evidence as very low due to risk of bias, inconsistency across the studies, and imprecise effect estimates. No trials reported on moderate-severe neurodevelopmental impairment at 18 to 26 months or BPD at 28 days of age. The remaining three outcomes were reported in a single trial. On the basis of this trial, we are uncertain whether low or moderate-high nasal CPAP levels improve the outcomes of: death or BPD at 36 weeks' PMA (RR 0.87, 95% CI 0.51 to 1.49; 1 trial, 93 participants); mortality by hospital discharge (RR 2.94, 95% CI 0.12 to 70.30; 1 trial, 93 participants), and BPD at 36 weeks' PMA (RR 0.87, 95% CI 0.51 to 1.49; 1 trial, 93 participants). We assessed the certainty of the evidence as very low for all three outcomes due to risk of bias, a lack of consistency across multiple studies, and imprecise effect estimates.  AUTHORS' CONCLUSIONS: There are insufficient data from randomized trials to guide nasal CPAP level selection in preterm infants, whether provided as initial respiratory support or following extubation from invasive mechanical ventilation. We are uncertain as to whether low or moderate-high nasal CPAP levels improve morbidity and mortality in preterm infants. Well-designed trials evaluating this important aspect of a commonly used neonatal therapy are needed.

Regional ventilation characteristics during non-invasive respiratory support in preterm infants

OBJECTIVES

To determine the regional ventilation characteristics during non-invasive ventilation (NIV) in stable preterm infants. The secondary aim was to explore the relationship between indicators of ventilation homogeneity and other clinical measures of respiratory status.

DESIGN

Prospective observational study.

SETTING

Two tertiary neonatal intensive care units.

PATIENTS

Forty stable preterm infants born <30 weeks of gestation receiving either continuous positive airway pressure (n=32) or high-flow nasal cannulae (n=8) at least 24 hours after extubation at time of study.

INTERVENTIONS

Continuous electrical impedance tomography imaging of regional ventilation during 60 min of quiet breathing on clinician-determined non-invasive settings.

MAIN OUTCOME MEASURES

Gravity-dependent and right-left centre of ventilation (CoV), percentage of whole lung tidal volume (V_T) by lung region and percentage of lung unventilated were determined for 120 artefact-free breaths/infant (4770 breaths included). Oxygen saturation, heart and respiratory rates were also measured.

RESULTS

Ventilation was greater in the right lung (mean 69.1 (SD 14.9)%) total V_T and the gravity-non-dependent (ND) lung; ideal-actual CoV 1.4 (4.5)%. The central third of the lung received the most V_T, followed by the non-dependent and dependent regions (p<0.0001 repeated-measure analysis of variance). Ventilation inhomogeneity was associated with worse peripheral capillary oxygen saturation (SpO₂)/fraction of inspired oxygen (FiO₂) (p=0.031, r² 0.12; linear regression). In those infants that later developed bronchopulmonary dysplasia (n=25), SpO₂/FiO₂ was worse and non-dependent ventilation inhomogeneity was greater than in those that did not (both p<0.05, t-test Welch correction).

CONCLUSIONS

There is high breath-by-breath variability in regional ventilation patterns during NIV in preterm infants. Ventilation favoured the ND lung, with ventilation inhomogeneity associated with worse oxygenation.

Effects of two modalities of noninvasive ventilation on breathing pattern of very low birth weight preterm infants immediately after extubation: a quasi-experimental study

AIM

The primary objective of this study was to investigate the effects of two modalities of noninvasive ventilation, continuous positive airway pressure-CPAP and non-synchronized nasal intermittent positive pressure ventilation-nsNIPPV, on breathing pattern of very low birth weight preterm infants immediately after extubation.

METHODS

It was conducted a quasi-experimental study at a public university hospital. Infants with gestacional age ≤32 weeks and birth weight ≤1,500 g were randomized into the sequences, prior extubation: CPAP - nsNIPPV (1) or nsNIPPV - CPAP (2). Each preterm infant was studied for a period of 60 min in each ventilatory mode. Respiratory inductive plethysmography was used to assess breathing pattern. Inferential analysis was performed by repeated measures ANOVA or Friedman test.

RESULTS

Eleven preterm infants were studied and a total of 7,564 respiratory cycles were analyzed. No significant differences were observed in any of the comparisons made for any of the breathing pattern variables (p > .05).

CONCLUSIONS

There was no significant difference on breathing pattern between CPAP and nsNIPPV of preterm infants after extubation.

Reducing post-extubation failure rates in very preterm infants: is BiPAP better than CPAP?

Background and Aim: Continuous positive airway pressure (CPAP) is currently used in neonates after mechanical ventilation though it may occasionally be associated with air leaks syndromes or it may fail to support the baby. The pressure difference offered by bilevel continuous positive distending pressure (BiPAP) respect to CPAP may be an advantage to the spontaneously breathing patient. In this study, we compared the efficacy of CPAP and BiPAP in the firstweek post-extubation in a series of very preterm infants.Methods: Inborn neonates less than 30 weeks of gestational age who were intubated shortly after birth from January 2011 to December 2017 were enrolled in a retrospective study. The attending clinician assessed the patients for non-invasive respiratory support readiness and allocated them to CPAP (PEEP 4-6 cmH₂O) or BiPAP (PEEP 4-5 cmH₂O, rate 10-40; Thigh 0.7-1.2; upper-pressure level 8-10 cmH₂O). Both techniques were compared for preventing extubation failure within 7 days from extubation as defined per local protocol (primary outcome). Secondary outcomes were: definitive failure of extubation, pneumothorax during non-invasive respiratory support, periventricular leukomalacia, bronchopulmonary dysplasia, sepsis, patent ductus arteriosus and retinopathy of prematurity at discharge.Results: We enrolled 134 neonates; the CPAP group included 89 babies while 45 received BiPAP. Patients did not differ for their general characteristics (EG, antenatal steroids, incidence of SGA, maternal hypertension, surfactant replacement therapy). Short term extubation failure was significantly higher in the former group (23/89 in CPAP vs 5/45 in BiPAP; p = .005). No infant developed air leak syndrome. Secondary outcomes were comparable between groups. Multivariate analysis showed that on the whole population the extubation failure was correlated to the insurgence of late-onset sepsis.Conclusion: BiPAP safely reduced early extubation failure compared to CPAP in our cohort of very preterm neonates within 7 days from extubation.

Tools to assess lung aeration in neonates with respiratory distress syndrome

AIM

Respiratory distress syndrome is a common condition among preterm neonates, and assessing lung aeration assists in diagnosing the disease and helping to guide and monitor treatment. We aimed to identify and analyse the tools available to assess lung aeration in neonates with respiratory distress syndrome.

METHODS

A systematic review and narrative synthesis of studies published between January 1, 2004, and August 26, 2019, were performed using the OVID Medline, PubMed, Embase and Scopus databases.

RESULTS

A total of 53 relevant papers were retrieved for the narrative synthesis. The main tools used to assess lung aeration were respiratory function monitoring, capnography, chest X-rays, lung ultrasound, electrical impedance tomography and respiratory inductive plethysmography. This paper discusses the evidence to support the use of these tools, including their advantages and disadvantages, and explores the future of lung aeration assessments within neonatal intensive care units.

CONCLUSION

There are currently several promising tools available to assess lung aeration in neonates with respiratory distress syndrome, but they all have their limitations. These tools need to be refined to facilitate convenient and accurate assessments of lung aeration in neonates with respiratory distress syndrome.

Precision Medicine in Neonates: Future Perspectives for the Lung

Bronchopulmonary dysplasia (BPD) is the most common complication of pre-term birth with long lasting sequelae. Since its first description more than 50 years ago, many large randomized controlled trials have been conducted, aiming to improve evidence-based knowledge on the optimal strategies to prevent and treat BPD. However, most of these intervention studies have been performed on a population level without regard for the variation in clinical and biological diversity (e.g., gestational age, ethnicity, gender, or disease progression) between patients that is driven by the complex interaction of genetic pre-disposition and environmental exposures. Nevertheless, clinicians provide daily care such as lung protective interventions on an individual basis every day despite the fact that research supporting individualized or precision medicine for monitoring or treating pre-term lungs is immature. This narrative review summarizes four potential developments in pulmonary research that might facilitate the process of individualizing lung protective interventions to prevent development of BPD. Electrical impedance tomography and electromyography of the diaphragm are bedside monitoring tools to assess regional changes in lung volume and ventilation and spontaneous breathing effort, respectively. These non-invasive tools allow a more individualized optimization of invasive and non-invasive respiratory support. Investigation of the genomic variation in caffeine metabolism in pre-term infants can be used to optimize and individualize caffeine dosing regimens. Finally, volatile organic compound analysis in exhaled breath might accurately predict BPD at an early stage of the disease, enabling clinicians to initiate preventive strategies for BPD on an individual basis. Before these suggested diagnostic or monitoring tools can be implemented in daily practice and improve individualized patient care, future research should address and overcome their technical difficulties, perform extensive external validation and show their additional value in preventing BPD.

Nasal Intermittent Mandatory Ventilation Versus Nasal Continuous Positive Airway Pressure Before and After Invasive Ventilatory Support

Continuous positive airway pressure (CPAP), noninvasive intermittent positive pressure ventilation (NIPPV), and heated humidified high-flow nasal cannula (HHFNC) are modes of noninvasive respiratory support used in neonatal practice. These modes of noninvasive respiratory support may obviate mechanical ventilation, prevent extubation failure, and reduce the risk of developing bronchopulmonary dysplasia. Although the physiologic bases of CPAP and HHFNC are well delineated, and their modes and practical application consistent, those of NIPPV are unproven and varied. Available evidence suggests that NIPPV is superior to CPAP as a primary and postextubation respiratory support in preterm infants.

Regional Volume Characteristics of the Preterm Infant Receiving First Intention Continuous Positive Airway Pressure

OBJECTIVE

To determine whether applying nasal continuous positive airway pressure (CPAP) using systematic changes in continuous distending pressure (CDP) results in a quasi-static pressure-volume relationship in very preterm infants receiving first intention CPAP in the first 12-18 hours of life.

STUDY DESIGN

Twenty infants at <32 weeks' gestation with mild respiratory distress syndrome (RDS) managed exclusively with nasal CPAP had CDP increased from 5 to 8 to 10 cmH₂O, and then decreased to 8 cmH₂O and returned to baseline CDP. Each CDP was maintained for 20 min. At each CDP, relative impedance change in end-expiratory thoracic volume (ΔZEEV) and tidal volume (ΔZV_T) were measured using electrical impedance tomography. Esophageal pressure (P_oes) was measured as a proxy for intrapleural pressure to determine transpulmonary pressure (P_tp).

RESULTS

Overall, there was a relationship between P_tp and global ΔZEEV representing the pressure-volume relationship in the lungs. There were regional variations in ΔZEEV, with 13 infants exhibiting hysteresis with the greatest gains in EEV and tidal volume in the dependent lung with no hemodynamic compromise. Seven infants did not demonstrate hysteresis during decremental CDP changes.

CONCLUSION

It was possible to define a pressure-volume relationship of the lung and demonstrate reversal of atelectasis by systematically manipulating CDP in most very preterm infants with mild RDS. This suggests that CDP manipulation can be used to optimize the volume state of the preterm lung.

Diaphragmatic activity during weaning from respiratory support in preterm infants

OBJECTIVE

To determine if weaning from nasal continuous positive airway pressure (nCPAP) to lesser supportive low flow nasal cannula (LFNC) results in a change in electrical activity of the diaphragm in preterm infants.

DESIGN

Prospective observational study.

SETTING

Neonatal intensive care unit.

PATIENTS

Stable preterm infants weaned from nCPAP to LFNC (1 L/min).

MAIN OUTCOME MEASURES

Change in diaphragmatic activity, expressed as amplitude, peak and tonic activity, measured by transcutaneous electromyography (dEMG) from 30 min before (baseline) until 180 min after weaning. Subgroup analysis was performed based on success or failure of the weaning attempt.

RESULTS

Fifty-nine preterm infants (gestational age: 29.0±2.4 weeks, birth weight: 1210±443 g) accounting for 74 weaning attempts were included. A significant increase in dEMG amplitude (median, IQR: 21.3%, 3.6-41.4), peak (22.1%, 8.7-40.5) and tonic activity (14.3%, -1.9-38.1) was seen directly after weaning. This effect slowly decreased over time. Infants failing the weaning attempt tended to have a higher diaphragmatic activity than those successfully weaned.

CONCLUSIONS

Weaning from nCPAP to LFNC leads to an increase in diaphragmatic activity measured by dEMG and is most prominent in preterm infants failing the weaning attempt. dEMG monitoring might be a useful parameter to guide weaning from respiratory support in preterm infants.

Efficacy of minimally invasive surfactant therapy in moderate and late preterm infants: A multicentre randomized control trial

BACKGROUND

Minimally invasive surfactant therapy (MIST) is a new strategy to avoid mechanical ventilation (MV) in respiratory distress syndrome. The primary aim of this study was to test MIST as a means of avoiding MV exposure and pneumothorax occurrence in moderate and late preterm infants (32 to 36 weeks' gestational age).

METHODS

This was a randomized controlled trial including three Canadian centres. Patients were randomized to standard management or to the intervention if they required nasal continuous positive airway pressure of 6 cm H2O and 35% FiO2 in the first 24 hours of life. Patients from the intervention group received MIST immediately after inclusion. The primary outcome was either need for MV or development of a pneumothorax requiring a chest tube. To ensure that clinicians were not biased toward delaying intubation in the intervention group, clinical failure criteria were also used as a primary outcome. The primary outcome was analyzed using bivariate and multivariate logistic regressions.

RESULTS

Among 45 randomized patients, 24 were assigned to MIST and 21 to standard management. Eight infants (33%) from the intervention group met the primary outcome criteria versus 19 (90%) in the control group (absolute risk reduction 0.57, 95% confidence interval 0.54 to 0.60). One patient in each group reached the primary outcome because of pneumothorax occurrence. The other patients were exposed to MV. None of the patients reached the clinical failure criteria.

CONCLUSION

MIST for respiratory distress syndrome management in moderate and late preterm infants was associated with a significant reduction of MV exposure and pneumothorax occurrence.

Short-term effects of neuromuscular blockade on global and regional lung mechanics, oxygenation and ventilation in pediatric acute hypoxemic respiratory failure

Background

Neuromuscular blockade (NMB) has been shown to improve outcome in acute respiratory distress syndrome (ARDS) in adults, challenging maintaining spontaneous breathing when there is severe lung injury. We tested in a prospective physiological study the hypothesis that continuous administration of NMB agents in mechanically ventilated children with severe acute hypoxemic respiratory failure (AHRF) improves the oxygenation index without a redistribution of tidal volume V_T toward non-dependent lung zones.

Methods

Oxygenation index, PaO₂/FiO₂ ratio, lung mechanics (plateau pressure, mean airway pressure, respiratory system compliance and resistance), hemodynamics (heart rate, central venous and arterial blood pressures), oxygenation [oxygenation index (OI), PaO₂/FiO₂ and SpO₂/FiO₂], ventilation (physiological dead space-to-V_T ratio) and electrical impedance tomography measured changes in end-expiratory lung volume (EELV), and V_T distribution was measured before and 15 min after the start of continuous infusion of rocuronium 1 mg/kg. Patients were ventilated in a time-cycled, pressure-limited mode with pre-set V_T. All ventilator settings were not changed during the study.

Results

Twenty-two patients were studied (N = 18 met the criteria for pediatric ARDS). Median age (25–75 interquartile range) was 15 (7.8–77.5) weeks. Pulmonary pathology was present in 77.3%. The median lung injury score was 9 (8–10). The overall median CoV and regional lung filling characteristics were not affected by NMB, indicating no ventilation shift toward the non-dependent lung zones. Regional analysis showed a homogeneous time course of lung inflation during inspiration, indicating no tendency to atelectasis after the introduction of NMB. NMB decreased the mean airway pressure (p = 0.039) and OI (p = 0.039) in all patients. There were no significant changes in lung mechanics, hemodynamics and EELV. Subgroup analysis showed that OI decreased (p = 0.01) and PaO₂/FiO₂ increased (p = 0.02) in patients with moderate or severe PARDS.

Conclusions

NMB resulted in an improved oxygenation index in pediatric patients with AHRF. Distribution of V_T and regional lung filling characteristics were not affected.

Nasal intermittent positive pressure ventilation in preterm infants: Equipment, evidence, and synchronization

The use of nasal intermittent positive pressure ventilation (NIPPV) as respiratory support for preterm infants is well established. Evidence from randomized trials indicates that NIPPV is advantageous over continuous positive airway pressure (CPAP) as post-extubation support, albeit with varied outcomes between NIPPV techniques. Randomized data comparing NIPPV with CPAP as primary support, and for the treatment of apnea, are conflicting. Intrepretation of outcomes is limited by the multiple techniques and devices used to generate and deliver NIPPV. This review discusses the potential mechanisms of action of NIPPV in preterm infants, the evidence from clinical trials, and summarizes recommendations for practice.

Effect of Minimally Invasive Surfactant Therapy on Lung Volume and Ventilation in Preterm Infants

OBJECTIVE

To assess the changes in (regional) lung volume and gas exchange during minimally invasive surfactant therapy (MIST) in preterm infants with respiratory distress syndrome.

STUDY DESIGN

In this prospective observational study, infants requiring a fraction of inspired oxygen (FiO2) ≥ 0.30 during nasal continuous positive airway pressure of 6 cmH2O were eligible for MIST. Surfactant (160-240 mg/kg) was administered in supine position in 1-3 minutes via an umbilical catheter placed 2 cm below the vocal cords. Changes in end-expiratory lung volume (EELV), tidal volume, and its distribution were recorded continuously with electrical impedance tomography before and up to 60 minutes after MIST. Changes in transcutaneous oxygen saturation (SpO2) and partial carbon dioxide pressure, FiO2, respiratory rate, and minute ventilation were recorded.

RESULTS

A total of 16 preterm infants were included. One patient did not finish study protocol because of severe apnea 10 minutes after MIST. In the remaining infants (gestational age 29.8 ± 2.8 weeks, body weight 1545 ± 481 g) EELV showed a rapid and sustained increase, starting in the dependent lung regions, followed by the nondependent regions approximately 5 minutes later. Oxygenation, expressed as the SpO2/FiO2 ratio, increased from 233 (IQR 206-257) to 418 (IQR 356-446) after 60 minutes (P < .001). This change was significantly correlated with the change in EELV (ρ = 0.70, P < .01). Tidal volume and minute volume decreased significantly after MIST, but transcutaneous partial carbon dioxide pressure was comparable with pre-MIST values. Ventilation distribution remained unchanged.

CONCLUSIONS

MIST results in a rapid and homogeneous increase in EELV, which is associated with an improvement in oxygenation.

The effect of prolonged lateral positioning during routine care on regional lung volume changes in preterm infants

INTRODUCTION

During routine nursing care, preterm infants are often placed in lateral position for several hours, but the effect of this procedure on regional lung volume and ventilation is unknown. In our study we examined this effect during 3 hrs of lateral positioning in stable preterm infants.

METHODS

Preterm infants on non-invasive respiratory support were eligible for the study. Infants were placed in supine position and subsequently transferred to right or left lateral position, according to their individual routine nursing schedule. Changes in end-expiratory lung volume (EELV), tidal volume (VT ) and ventilation distribution were recorded using electrical impedance tomography (EIT), starting 10 min before and up to 180 min after the positional change. Additionally, oxygen requirement, transcutaneous oxygen saturation and respiratory rate were recorded.

RESULTS

15 infants were included (GA 28.9 ± 2.0 wk, BW 1167 ± 290 g). EELV increased significantly after changing to lateral position, stabilizing at a median value of 40.8 (IQR 29.0-99.3) AU/kg at 30 min. This increase could almost be exclusively attributed to the non-dependent lung regions. Tidal volume, oxygenation, and respiratory rate remained stable. Changing to the right, but not the left, lateral position resulted in a rapid but transient shift in ventilation to the dependent lung regions. After 180 min there were no differences in ventilation distribution between lateral and supine positioning.

CONCLUSION

This study shows that lateral position up to 3 hours, as part of normal nursing care of preterm infants, has no adverse effects on lung volumes and its regional distribution.

Noninvasive Respiratory Support

Mechanical ventilation is associated with increased survival of preterm infants but is also associated with an increased incidence of chronic lung disease (bronchopulmonary dysplasia) in survivors. Nasal continuous positive airway pressure (nCPAP) is a form of noninvasive ventilation that reduces the need for mechanical ventilation and decreases the combined outcome of death or bronchopulmonary dysplasia. Other modes of noninvasive ventilation, including nasal intermittent positive pressure ventilation, biphasic positive airway pressure, and high-flow nasal cannula, have recently been introduced into the NICU setting as potential alternatives to mechanical ventilation or nCPAP. Randomized controlled trials suggest that these newer modalities may be effective alternatives to nCPAP and may offer some advantages over nCPAP, but efficacy and safety data are limited.

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.

In vitro study on work of breathing during non-invasive ventilation using a new variable flow generator

OBJECTIVE

In an attempt to reduce the work of breathing (WOB) and the risk of respiratory failure, preterm infants are increasingly treated with nasal synchronised biphasic positive airway pressure (BPAP) via the Infant Flow SiPAP system. However, the relatively high resistance of the generator limits the pressure amplitude (PA) and pressure build-up (PB) of this system. This in vitro study investigates the impact of a new generator with improved fluid mechanics on the WOB, PA and PB during BPAP.

METHODS

Using a low compliance lung model, WOB, PA and PB, were measured during BPAP using the old and the new Infant Flow generators. Airway resistance (tube sizes 2.5 mm, 3.0 mm and 3.5 mm), nasal interface sizes (small, medium and large) and four different ventilator settings were used to mimic different clinical conditions.

RESULTS

Compared with the old generator, the new generator significantly reduced the WOB between 10% and 70%, depending on the measurement configuration. The maximum PA was higher when using the new (6-7 cm H2O) generator versus the old (3-4 cm H2O) generator. During the first 100 ms of inspiration, the new generator reached between 33% and 40% of the peak pressure compared with 11-20% for the old generator.

CONCLUSIONS

This in vitro study shows that a new generator of the Infant Flow SiPAP device results in a significant reduction in WOB and an increase in PA and PB during BPAP. The results of this study need to be confirmed under variable clinical conditions in preterm infants.

Changes in lung volume and ventilation following transition from invasive to noninvasive respiratory support and prone positioning in preterm infants

BACKGROUND

To minimize secondary lung injury, ventilated preterm infants are extubated as soon as possible. To maximize extubation success, they are often placed in prone position. The effect of extubation and subsequent prone positioning on lung volumes is currently unknown.

METHODS

Changes in end-expiratory lung volume (ΔEELV), tidal volume (VT), and ventilation distribution were monitored during transition from endotracheal to nasal continuous positive airway pressure and following prone positioning using electrical impedance tomography. In addition, the continuous distending pressure (CDP) and oxygen need (FiO₂) were recorded.

RESULTS

Twenty preterm infants (GA 28.7 ± 1.7 wk) were included. Following extubation, the CDP decreased from 7.9 ± 0.5 to 6.0 ± 0.2 cmH₂O, while the FiO₂ remained stable. Both ΔEELV and VT increased significantly (P < 0.05) after extubation, without changing ventilation distribution. Prone positioning resulted in a further increase in ΔEELV (P < 0.01) and a decrease in respiratory rate. VT remained stable but its distribution clearly shifted toward the ventral lung regions.

CONCLUSION

Infants who are transitioned from invasive to noninvasive respiratory support are able to maintain their EELV and increase their VT. Prone positioning increases EELV and shifts tidal ventilation to the ventral lung regions. The latter suggests that infants should preferably be placed in prone position after extubation.

Electrical impedance tomography imaging of the cardiopulmonary system

PURPOSE OF REVIEW

This review article summarizes the recent advances in electrical impedance tomography (EIT) related to cardiopulmonary imaging and monitoring on the background of the 30-year development of this technology.

RECENT FINDINGS

EIT is expected to become a bedside tool for monitoring and guiding ventilator therapy. In this context, several studies applied EIT to determine spatial ventilation distribution during different ventilation modes and settings. EIT was increasingly combined with other signals, such as airway pressure, enabling the assessment of regional respiratory system mechanics. EIT was for the first time used prospectively to define ventilator settings in an experimental and a clinical study. Increased neonatal and paediatric use of EIT was noted. Only few studies focused on cardiac function and lung perfusion. Advanced radiological imaging techniques were applied to assess EIT performance in detecting regional lung ventilation. New approaches to improve the quality of thoracic EIT images were proposed.

SUMMARY

EIT is not routinely used in a clinical setting, but the interest in EIT is evident. The major task for EIT research is to provide the clinicians with guidelines how to conduct, analyse and interpret EIT examinations and combine them with other medical techniques so as to meaningfully impact the clinical decision-making.

Functional validation and comparison framework for EIT lung imaging

INTRODUCTION

Electrical impedance tomography (EIT) is an emerging clinical tool for monitoring ventilation distribution in mechanically ventilated patients, for which many image reconstruction algorithms have been suggested. We propose an experimental framework to assess such algorithms with respect to their ability to correctly represent well-defined physiological changes. We defined a set of clinically relevant ventilation conditions and induced them experimentally in 8 pigs by controlling three ventilator settings (tidal volume, positive end-expiratory pressure and the fraction of inspired oxygen). In this way, large and discrete shifts in global and regional lung air content were elicited.

METHODS

We use the framework to compare twelve 2D EIT reconstruction algorithms, including backprojection (the original and still most frequently used algorithm), GREIT (a more recent consensus algorithm for lung imaging), truncated singular value decomposition (TSVD), several variants of the one-step Gauss-Newton approach and two iterative algorithms. We consider the effects of using a 3D finite element model, assuming non-uniform background conductivity, noise modeling, reconstructing for electrode movement, total variation (TV) reconstruction, robust error norms, smoothing priors, and using difference vs. normalized difference data.

RESULTS AND CONCLUSIONS

Our results indicate that, while variation in appearance of images reconstructed from the same data is not negligible, clinically relevant parameters do not vary considerably among the advanced algorithms. Among the analysed algorithms, several advanced algorithms perform well, while some others are significantly worse. Given its vintage and ad-hoc formulation backprojection works surprisingly well, supporting the validity of previous studies in lung EIT.

Synchronized neonatal non-invasive ventilation-a pilot study: the graseby capsule with bi-level NCPAP

OBJECTIVES

(1) To evaluate the Graseby capsule (GC) as a respiratory detection device when compared to respiratory inductance plethysmography (RIP); (2) to evaluate the response to the Graseby signal of a commercially available bi-level nasal CPAP device (BNCPAP) designed for use with the GC; and (3) to assess the performance of the GC/BNCPAP device when fitted on preterm infants.

STUDY DESIGN

The study consisted of four parts: (1) The response characteristics of the GC/BNCPAP were assessed without connection to an infant; (2) the respiratory detection of both GC and RIP were compared in six preterm infants (mean 1,242 g, range 900-1,530 g); (3) the GC/BNCPAP was connected in six preterm infants (mean 1,568 g, range 1,040-1,835 g), isolating the BNCPAP and the infant interaction by substituting an artificial "nose" for the infant and assessing performance using inspiratory times (Ti) of 0.1 through 0.5 sec with pressure levels of both 10/6 and 8/5 cmH2 O; and (4) the GC/BNCPAP was employed as a respiratory support device in six preterm infants (mean 1,189 g, range 785-1,795 g) using clinically required pressures and evaluating performance using Ti of 0.3, 0.4 and 0.5 sec.

RESULTS

(1) Within 26 ms of stimulation of the GC, the BNCPAP initiated air flow; however, the time to reach peak pressure was much longer; (2) the GC, when placed in the subxiphoid position, tracked the RIP signal nearly identically and occurred sooner; (3) a Ti of at least 0.3 sec was required to reach the desired high pressure setting; and (4) synchrony of the GC/BNCPAP occurred in 72-74% of infant breaths.

CONCLUSIONS

The GC is a sensitive respiratory detection device; however, the GC/BNCPAP interface requires a minimum Ti of 0.3 sec and an adequate respiratory effort to achieve the desired pressure and to synchronously trigger the BNCPAP.

Pulmonary function testing in children and infants

Pulmonary function testing is performed in children and infants with the aim of documenting lung development with age and making diagnoses of lung diseases. In children and infants with an established lung disease, pulmonary function is tested to assess the disease progression and the efficacy of therapy. It is difficult to carry out the measurements in this age group without disturbances, so obtaining results of good quality and reproducibility is challenging. Young children are often uncooperative during the examinations. This is partly related to their young age but also due to the long testing duration and the unpopular equipment. We address a variety of examination techniques for lung function assessment in children and infants in this review. We describe the measuring principles, examination procedures, clinical findings and their interpretation, as well as advantages and limitations of these methods. The comparability between devices and centres as well as the availability of reference values are still considered a challenge in many of these techniques. In recent years, new technologies have emerged allowing the assessment of lung function not only on the global level but also on the regional level. This opens new possibilities for detecting regional lung function heterogeneity that might lead to a better understanding of respiratory pathophysiology in children.

Role of electrical impedance tomography in clinical practice in pediatric respiratory medicine

This paper summarizes current knowledge about electrical impedance tomography (EIT) and its present and possible applications in clinical practice in pediatric respiratory medicine. EIT is a relatively new technique based on real-time monitoring of bioimpedance. Its possible application in clinical practice related to ventilation and perfusion monitoring in children has gaine increasing attention in recent years. Most of the currently published data is based on studies performed on small and heterogenous groups of patients. Thus the results need to be corroborated in future well-designed clinical trials. Firstly a short theoretical overview summarizing physical principles and main advantages and disadvantages is provided. It is followed by a review of the current data regarding EIT application in ventilation distribution monitoring in healthy individuals. Finally the most important studies utilizing EIT in ventilation and perfusion monitoring in critically ill newborns and children are outlined.