Application of neurally adjusted ventilatory assist in neonates

Novel forms of ventilation in neonates: Neurally adjusted ventilatory assist and proportional assist ventilation

Patient-triggered modes of ventilation are currently the standard of practice in the care of term and preterm infants. Maintaining spontaneous breathing during mechanical ventilation promotes earlier weaning and possibly reduces ventilator-induced diaphragmatic dysfunction. A further development of assisted ventilation provides support in proportion to the respiratory effort and enables the patient to have full control of their ventilatory cycle. In this paper we will review the literature on two of these modes of ventilation: neurally adjusted ventilatory assist (NAVA) and proportional assist ventilation (PAV), propose future studies and suggest clinical applications of these modes.

Trends in the Incidence of Bronchopulmonary Dysplasia after the Introduction of Neurally Adjusted Ventilatory Assist (NAVA)

OBJECTIVE

This study investigates the difference in the rates of bronchopulmonary dysplasia in very low birth weight infants before and after the introduction of neurally adjusted ventilatory assist (NAVA).

STUDY DESIGN

A retrospective cohort study comparing rates of Bronchopulmonary dysplasia (BPD) before and after implementation of NAVA. Eligibility criteria included all very low birth weight VLBW neonates needing ventilation. For analysis, each cohort was divided into three subgroups based on gestational age. Changes in the rate of BPD, length of stay, tracheostomy rates, invasive ventilator days, and home oxygen therapy were compared.

RESULTS

There were no differences in the incidence of BPD in neonates at 23-25 6/7 weeks' and 29-32 weeks' gestation between the two cohorts. A higher incidence of BPD was seen in the 26-28 5/7 weeks' gestation NAVA subgroup compared to controls (86% vs. 68%, p = 0.05). No significant difference was found for ventilator days, but infants in the 26-28 6/7 subgroup in the NAVA cohort had a longer length of stay (98 ± 34 days vs. 82 ± 24 days, p = 0.02), a higher percentage discharged on home oxygen therapy (45% vs. 18%, respectively, p = 0.006), and higher tracheostomy rates (3/36 vs. 0/60, p = 0.02), compared to the control group.

CONCLUSIONS

The NAVA mode was not associated with a reduction in BPD when compared to other modes of ventilation. Unexpected increases were seen in BPD rates, home oxygen therapy rates, tracheostomy rates, and the length of stay in the NAVA subgroup born at 26-28 6/7 weeks' gestation.

Improved respiratory parameters with skin-to-skin contact in premature infants with bronchopulmonary dysplasia on NIV-NAVA

AIM

To determine if skin-to-skin contact (SSC) improved respiratory parameters in premature infants with evolving or established bronchopulmonary dysplasia (BPD) on non-invasive neutrally adjusted ventilator assist (NIV-NAVA).

METHODS

Premature infants (<32 weeks gestational age) with BPD on NIV-NAVA were studied. Continuous readings from the Edi catheter (modified nasogastric feeding tube inserted for NAVA ventilation) were compared: pre-SSC (baby in incubator) and end-SSC (just before end of SSC).

RESULTS

Sixty-five episodes of SSC were recorded in 12 premature infants with median gestational age at birth of 24.4 (23.1-27.0) weeks and birth weight of 642 (530-960) grams. Peak Edi (uV) in end-SSC 11.5 (2.7-38.7) was significantly lower compared to pre-SSC 15.8 (4.0-36.6), p < 0.001. P mean (cmH₂ O) was significantly lower in end-SSC 9.7 (7.3-15.4) compared to pre-SSC 10.3 (7.5-15.5), p = 0.008. Respiratory rate (breaths/min) was significantly lower in end-SSC 52.9 (31.1-78.1) compared to pre-SSC 53.4 (35.1-74.1), p = 0.031. There was no significant difference in inspired oxygen requirement or time on back-up mode in end-SSC 40.0 (22.1-56.1) and 5.9 (0.0-56.0) compared to pre-SSC 39.0 (26.0-56.1) and 5.1 (0.0-29.3), p = 0.556 and p = 0.853 respectively.

CONCLUSION

SSC improved respiratory parameters in premature infants with evolving or established BPD on NIV-NAVA.

Respiratory physiology during NAVA ventilation in neonates born with a congenital diaphragmatic hernia: The "NAVA-diaph" pilot study

BACKGROUND

Neurally adjusted ventilatory assist (NAVA) is a ventilatory mode that delivers synchronized ventilation, proportional to the electrical activity of the diaphragm (EAdi). Although it has been proposed in infants with a congenital diaphragmatic hernia (CDH), the diaphragmatic defect and the surgical repair could alter the physiology of the diaphragm.

AIM

To evaluate, in a pilot study, the relationship between the respiratory drive (EAdi) and the respiratory effort in neonates with CDH during the postsurgical period under either NAVA ventilation or conventional ventilation (CV).

METHODS

This prospective physiological study included eight neonates admitted to a neonatal intensive care unit with a diagnosis of CDH. EAdi, esophageal, gastric, and transdiaphragmatic pressure, as well as clinical parameters, were recorded during NAVA and CV (synchronized intermittent mandatory pressure ventilation) in the postsurgical period.

RESULTS

EAdi was detectable and there was a correlation between the ΔEAdi (maximal - minimal values) and the transdiaphragmatic pressure (r = 0.26, 95% confidence interval [CI] [0.222; 0.299]). There was no significant difference in terms of clinical or physiological parameters during NAVA compared to CV, including work of breathing.

CONCLUSION

Respiratory drive and effort were correlated in infants with CDH and therefore NAVA is a suitable proportional mode in this population. EAdi can also be used to monitor the diaphragm for individualized support.

Convolutional neural network-based respiration analysis of electrical activities of the diaphragm

The electrical activity of the diaphragm (Edi) is considered a new respiratory vital sign for monitoring breathing patterns and efforts during ventilator care. However, the Edi signal contains irregular noise from complex causes, which makes reliable breathing analysis difficult. Deep learning was implemented to accurately detect the Edi signal peaks and analyze actual neural breathing in premature infants. Edi signals were collected from 17 premature infants born before gestational age less than 32 weeks, who received ventilatory support with a non-invasive neurally adjusted ventilatory assist. First, a local maximal detection method that over-detects candidate Edi peaks was used. Subsequently, a convolutional neural network-based deep learning was implemented to classify candidates into final Edi peaks. Our approach showed superior performance in all aspects of respiratory Edi peak detection and neural breathing analysis compared with the currently used recording technique in the ventilator. The method obtained a f1-score of 0.956 for the Edi peak detection performance and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${R}^{2}$$\end{document}R2 value of 0.823 for respiratory rates based on the number of Edi peaks. The proposed technique can achieve a more reliable analysis of Edi signals, including evaluation of the respiration rate in premature infants.

NIV-NAVA versus NCPAP immediately after birth in premature infants: A randomized controlled trial

OBJECTIVE

To evaluate whether noninvasive-neurally adjusted ventilatory assist (NIV-NAVA) decrease respiratory efforts compared to nasal continuous positive airway pressure (NCPAP) during the first hours of life.

METHODS

Twenty infants born between 28⁺⁰ and 31⁺⁶ weeks were randomized to NIV-NAVA or NCPAP. Positive end-expiratory pressure was constantly kept at 6 cmH₂O for both groups and the NAVA level was 1.0 cmH₂O/µV for NIV-NAVA group. The electrical activity of diaphragm (Edi) were recorded for the first two hours.

RESULTS

Peak and minimum Edi decreased similarly in both groups (P = 0.98 and P = 0.59, respectively). Leakages were higher in the NIV-NAVA group than in the NCPAP group (P < 0.001). The neural apnea defined as a flat Edi for ≥ 5 s were less frequent in NIV-NAVA group than in NCPAP group (P = 0.046).

CONCLUSIONS

Immediately applied NIV-NAVA in premature infants did not reduce breathing effort, measured as peak Edi. However, NIV-NAVA decreased neural apneic episodes compared to NCPAP.

Noninvasive Neurally Adjusted Ventilation in Postextubation Stabilization of Preterm Infants: A Randomized Controlled Study

OBJECTIVE

To compare the effects of noninvasive neurally adjusted ventilatory assist (NIV-NAVA) to nasal continuous positive airway pressure (NCPAP) in achieving successful extubation in preterm infants.

STUDY DESIGN

This prospective, single-center, randomized controlled trial enrolled preterm infants born at <30 weeks of gestation who received invasive ventilation. Participants were assigned at random to either NIV-NAVA or NCPAP after their first extubation from invasive ventilation. The primary outcome of the study was extubation failure within 72 hours of extubation. Electrical activity of the diaphragm (Edi) values were collected before extubation and at 1, 4, 12, and 24 hours after extubation.

RESULTS

A total of 78 infants were enrolled, including 35 infants in the NIV-NAVA group and 35 infants in the NCPAP group. Extubation failure within 72 hours of extubation was higher in the NCPAP group than in the NIV-NAVA group (28.6% vs 8.6%; P = .031). The duration of respiratory support and incidence of severe bronchopulmonary dysplasia were similar in the 2 groups. Peak and swing Edi values were comparable before and at 1 hour after extubation, but values at 4, 12, and 24 hours after extubation were lower in the NIV-NAVA group compared with the NCPAP group.

CONCLUSIONS

In the present trial, NIV-NAVA was more effective than NCPAP in preventing extubation failure in preterm infants.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02590757.

Implementation of neurally adjusted ventilatory assist and high flow nasal cannula in very preterm infants in a tertiary level NICU

Preterm infants treated with invasive ventilation are often affected by bronchopulmonary dysplasia, brain structure alterations, and later neurodevelopmental impairment. We studied the implementation of neurally adjusted ventilatory assist (NAVA) and high flow nasal cannula (HFNC) in a level III neonatal unit, and its effects on pulmonary and central nervous system outcomes. This retrospective cohort study included 193 surviving infants born below 32 weeks of gestation in preimplementation (2007-2008) and postimplementation (2016-2017) periods in a single study center in Finland. The proportion of infants requiring invasive ventilation decreased from 67% in the pre- to 48% in the postimplementation period (p = 0.009). Among infants treated with invasive ventilation, 68% were treated with NAVA after its implementation. At the same time, the duration of invasive ventilation of infants born at or below 28 weeks increased threefold compared with the preimplementation period (p = 0.042). The postimplementation period was characterized by a gradual replacement of nasal continuous positive airway pressure (nCPAP) with HFNC, earlier discontinuation of nCPAP, but a longer duration of positive pressure support. The proportion of normal magnetic resonance imaging (MRI) findings at term corrected age increased from 62% to 84% (p = 0.018). Cognitive outcome improved by one standard score between the study periods (p = 0.019). NAVA was used as the primary mode of ventilation in the postimplementation period. During this period, invasive ventilation time was significantly prolonged. HFNC led to a decrease in the use of nCPAP. The change in the respiratory support might have contributed to the improvement in brain MRI findings and cognitive outcomes.

Respiratory muscle function in the newborn: a narrative review

Our aim was to summarise the current evidence and methods used to assess respiratory muscle function in the newborn, focusing on current and future potential clinical applications. The respiratory muscles undertake the work of breathing and consist mainly of the diaphragm, which in the newborn is prone to dysfunction due to lower muscle mass, flattened shape and decreased content of fatigue-resistant muscle fibres. Premature infants are prone to diaphragmatic dysfunction due to limited reserves and limited capacity to generate force and avoid fatigue. Methods to assess the respiratory muscles in the newborn include electromyography, maximal respiratory pressures, assessment for thoraco-abdominal asynchrony and composite indices, such as the pressure-time product and the tension time index. Recently, there has been significant interest and a growing body of research in assessing respiratory muscle function using bedside ultrasonography. Neurally adjusted ventilator assist is a novel ventilation mode, where the level of the respiratory support is determined by the diaphragmatic electrical activity. Prolonged mechanical ventilation, hypercapnia and hypoxia, congenital anomalies and systemic or respiratory infection can negatively impact respiratory muscle function in the newborn, while caffeine and synchronised or volume-targeted ventilation have a positive effect on respiratory muscle function compared to conventional, non-triggered or pressure-limited ventilation, respectively. IMPACT: Respiratory muscle function is impaired in prematurely born neonates and infants with congenital anomalies, such as congenital diaphragmatic hernia. Respiratory muscle function is negatively affected by prolonged ventilation and infection and positively affected by caffeine and synchronised compared to non-synchronised ventilation modes. Point-of-care diaphragmatic ultrasound and neurally adjusted ventilator assist are recent diagnostic and therapeutic technological developments with significant clinical applicability.

Improved nutritional outcomes with neurally adjusted ventilatory assist (NAVA) in premature infants: a single tertiary neonatal unit's experience

During neurally adjusted ventilatory assist (NAVA)/non-invasive (NIV) NAVA, a modified nasogastric feeding tube with electrodes, monitors the electrical activity of the diaphragm (Edi). The Edi waveform determines the delivered pressure from the ventilator. Infant breathing is in synchrony with the ventilator and therefore is more comfortable with less work of breathing. Our aim was to determine if infants on NAVA had improved nutritional outcomes compared to infants managed on conventional respiratory support. A retrospective study was undertaken. Infants on NAVA were matched with two conventionally ventilated controls by gestational age, birth weight, sex, antenatal steroid exposure, and whether inborn or transferred ex utero. NAVA/NIV-NAVA was delivered by the SERVO-n® Maquet Getinge group ventilator. Conventional ventilation included pressure and volume control ventilation, and non-invasive ventilation included nasal intermittent positive pressure ventilation, triggered biphasic positive airway pressure, continuous positive airway pressure and heated humidified high flow oxygen. The measured outcome was discharge weight z scores. Eighteen "NAVA" infants with median gestational age (GA) of 25.3 (23.6-27.1) weeks and birth weight (BW) of 765 (580-1060) grams were compared with 36 controls with GA 25.2 (23.4-28) weeks (p = 0.727) and BW 743 (560-1050) grams (p = 0.727). There was no significant difference in the rates of postnatal steroids (61% versus 36% p = 0.093), necrotising enterocolitis (22% versus 11% p = 0.279) in the NAVA/NIV NAVA compared to the control group. There were slightly more infants who were breastfed at discharge in the NAVA/NIV NAVA group compared to controls: breast feeds (77.8% versus 58.3%), formula feeds (11.1% versus 30.6%), and mixed feeds (11.1% versus 11.1%), but this difference was not significant (p = 0.275). There was no significant difference in the birth z scores 0.235 (-1.56 to 1.71) versus -0.05 (-1.51 to -1.02) (p = 0.248) between the groups. However, the discharge z score was significantly in favour of the NAVA/NIV-NAVA group: -1.22 (-2.66 to -0.12) versus -2.17 (-3.79 to -0.24) in the control group (p = 0.033).Conclusion: The combination of NAVA/NIV-NAVA compared to conventional invasive and non-invasive modes may contribute to improved nutritional outcomes in premature infants.

The Intertemporal Role of Respiratory Support in Improving Neonatal Outcomes: A Narrative Review

Defining improvements in healthcare can be challenging due to the need to assess multiple outcomes and measures. In neonates, although progress in respiratory support has been a key factor in improving survival, the same degree of improvement has not been documented in certain outcomes, such as bronchopulmonary dysplasia. By exploring the evolution of neonatal respiratory care over the last 60 years, this review highlights not only the scientific advances that occurred with the application of invasive mechanical ventilation but also the weakness of the existing knowledge. The contributing role of non-invasive ventilation and less-invasive surfactant administration methods as well as of certain pharmacological therapies is also discussed. Moreover, we analyze the cost-benefit of neonatal care-respiratory support and present future challenges and perspectives.

Neurally Adjusted Ventilatory Assist in Very Prematurely Born Infants with Evolving/Established Bronchopulmonary Dysplasia

Background  During neurally adjusted ventilatory assist (NAVA)/noninvasive (NIV) NAVA, a modified nasogastric feeding tube with electrodes monitors the electrical activity of the diaphragm (Edi). The Edi waveform determines the delivered pressure from the ventilator. Objective  Our objective was to determine whether NAVA/NIV-NAVA has advantages in infants with evolving/established bronchopulmonary dysplasia (BPD). Methods  Each infant who received NAVA/NIV-NAVA and conventional invasive and NIV was matched with two historical controls. Eighteen NAVA/NIV-NAVA infants' median gestational age, 25.3 (23.6-28.1) weeks, was compared with 36 historical controls' median gestational age 25.2 (23.1-29.1) weeks. Results  Infants on NAVA/NIV-NAVA had lower extubation failure rates (median: 0 [0-2] vs. 1 [0-6] p  = 0.002), shorter durations of invasive ventilation (median: 30.5, [1-90] vs. 40.5 [11-199] days, p  = 0.046), and total duration of invasive and NIV to the point of discharge to the local hospital (median: 80 [57-140] vs. 103.5 [60-246] days, p  = 0.026). The overall length of stay (LOS) was lower in NAVA/NIVNAVA group (111.5 [78-183] vs. 140 [82-266] days, p  = 0.019). There were no significant differences in BPD (17/18 [94%] vs. 32/36 [89%] p  = 0.511) or home oxygen rates (14/18 [78%] vs. 23/36 [64%] p  = 0.305). Conclusion  The combination of NAVA/NIV-NAVA compared with conventional invasive and NIV modes may be advantageous for preterm infants with evolving/established BPD.

Application of neurally adjusted ventilatory assist in ventilator weaning of infants ventilator weaning

BACKGROUND

To analyze the application of neurally adjusted ventilatory assist in ventilator weaning of infants.

METHODS

A total of 25 infants (15 boys and 10 girls) who were mechanically ventilated by PICU in Hubei Maternal and Child Health Hospital were selected as the study subjects. After the improvement of the basic disease, regular spontaneous breathing, and the withdrawal of the ventilator, all the children obtained the electrical activity of the diaphragm (EAdi) signal. Then, each child was given CPAP and NAVA mode mechanical ventilation 1 h before the withdrawal of the ventilator. Each detection index was recorded 30 min after each mode of ventilation.

RESULTS

Two of the 25 children were tracheotomized because of respiratory muscle weakness and could not be converted to NAVA mode without the EAdi signal. Hemodynamic indexes were not statistically different between the two groups of CPAP and NAVA. PaCO₂ is not significantly different in the two modes, and both were at normal levels. The PIP in NAVA mode is lower than that in CPAP mode (p < .05), and its EAdi signal was correspondingly low. There were significant differences in the peak pressure (Ppeak), mean pressure (Pmean), and compliance and mean arterial pressure (p < .01) between the CPAP and NAVA model ventilation in 23 patients.

CONCLUSION

NAVA can significantly improve the coordination of patients. The therapeutic effect of NAVA was better, which was beneficial to the prognosis of patients and had positive application value in the withdrawal of ventilators in patients.

Proportional assist and neurally adjusted ventilation: Clinical knowledge and future trials in newborn infants

Different types of patient triggered ventilator modes have become the mainstay of ventilation in term and preterm newborn infants. Maintaining spontaneous breathing has allowed for earlier weaning and the additive effects of respiratory efforts combined with pre-set mechanical inflations have reduced mean airway pressures, both of which are important components in trying to avoid lung injury and promote normal lung development. New sophisticated modes of assisted ventilation have been developed during the last decades where the control of ventilator support is turned over to the patient. The ventilator detects the respiratory effort and adjusts ventilatory assistance proportionally to each phase of the respiratory cycle, thus enabling the patient to have full control of the start, the duration and the amount of ventilatory assistance. In this paper we will review the literature on the ventilatory modes of proportional assist ventilation and neurally adjusted ventilatory assistance, examine the different ways the signals are analyzed, propose future studies, and suggest ways to apply these modes in the clinical environment.

High CPAP vs. NIPPV in preterm neonates - A physiological cross-over study

OBJECTIVE

To evaluate the physiological impact of high CPAP (≥9 cmH2O) vs. NIPPV at equivalent mean airway pressures.

STUDY DESIGN

In this cross-over study, preterm neonates on high CPAP or NIPPV were placed on the alternate mode. After 30 min, left and right ventricular cardiac output and work of breathing indices were assessed, following which patients were placed back on the original mode and a similar procedure ensued.

RESULTS

Fifteen infants with mean (SD) postmenstrual age 32.7 (3.0) weeks, and weight 1569 (564) grams were included. No differences in LVO [320 (63) vs. 331 (86) mL/kg/min, P = 0.46] or RVO [420 (135) vs. 437 (141) mL/kg/min, P = 0.19] were noted during high CPAP vs. NIPPV, along with no differences in work of breathing indices.

CONCLUSION

High CPAP pressures did not adversely impact cardiac output or work of breathing compared to NIPPV at equivalent mean airway pressure.

Detection of Breathing Movements of Preterm Neonates by Recording Their Abdominal Movements with a Time-of-Flight Camera

In order to deliver an aerosolized drug in a breath-triggered manner, the initiation of the patient’s inspiration needs to be detected. The best-known systems monitoring breathing patterns are based on flow sensors. However, due to their large dead space volume, flow sensors are not advisable for monitoring the breathing of (preterm) neonates. Newly-developed respiratory sensors, especially when contact-based (invasive), can be tested on (preterm) neonates only with great effort due to clinical and ethical hurdles. Therefore, a physiological model is highly desirable to validate these sensors. For developing such a system, abdominal movement data of (preterm) neonates are required. We recorded time sequences of five preterm neonates’ abdominal movements with a time-of-flight camera and successfully extracted various breathing patterns and respiratory parameters. Several characteristic breathing patterns, such as forced breathing, sighing, apnea and crying, were identified from the movement data. Respiratory parameters, such as duration of inspiration and expiration, as well as respiratory rate and breathing movement over time, were also extracted. This work demonstrated that respiratory parameters of preterm neonates can be determined without contact. Therefore, such a system can be used for breathing detection to provide a trigger signal for breath-triggered drug release systems. Furthermore, based on the recorded data, a physiological abdominal movement model of preterm neonates can now be developed.

Breath-Triggered Drug Release System for Preterm Neonates

A major disadvantage of inhalation therapy with continuous drug delivery is the loss of medication during expiration. Developing a breath-triggered drug release system can highly decrease this loss. However, there is currently no breath-triggered drug release directly inside the patient interface (nasal prong) for preterm neonates available due to their high breathing frequency, short inspiration time and low tidal volume. Therefore, a nasal prong with an integrated valve releasing aerosol directly inside the patient interface increasing inhaled aerosol efficiency is desirable. We integrated a miniaturized aerosol valve into a nasal prong, controlled by a double-stroke cylinder. Breathing was simulated using a test lung for preterm neonates on CPAP respiratory support. The inhalation flow served as a trigger signal for the valve, releasing humidified surfactant. Particle detection was performed gravimetrically (filter) and optically (light extinction). The integrated miniaturized aerosol valve enabled breath-triggered drug release inside the patient interface with an aerosol valve response time of <25 ms. By breath-triggered release of the pharmaceutical aerosol as a bolus during inhalation, the inhaled aerosol efficiency was increased by a factor of >4 compared to non-triggered release. This novel nasal prong with integrated valve allows breath-triggered drug release directly inside the nasal prong with short response time.

Successful conservative managements of extensive pneumatoceles in a preterm girl: A case report

We describe a preterm girl with severe respiratory distress syndrome, which was managed with mechanical ventilation. She developed severe ventilator induced lung injury, causing extensive unilateral emphysema. CT-scan of the lungs corresponded with extensive pneumatoceles. She was managed conservatively, using neurally adjusted ventilatory assist, with success and was extubated on day of life 38. She was discharged home without any respiratory support at 39 weeks of postmenstrual age. Our case illustrates the ongoing risk of severe ventilator induced lung injury and highlights a unique injury pattern in a preterm newborn that was managed conservatively using neurally adjusted ventilatory assist with an excellent outcome.

Prolonged non-invasive ventilation in extremely low birth weight preterm infants is associated with bronchopulmonary dysplasia

AIM

To evaluate the association between the use of nasal continuous positive airway pressure (nCPAP) or nasal intermittent positive pressure ventilation (NIPPV) with the development of bronchopulmonary dysplasia (BPD).

METHODS

This is a single center retrospective cohort analysis of infants born at ≤1000 grams and ≤28 weeks gestation with respiratory distress treated with nCPAP or NIPPV. Groups were compared using Student's t test or chi-square, and associations estimated by logistic regression.

RESULTS

Compared to nCPAP, infants who received NIPPV had a higher incidence of moderate to severe (M-S) BPD (84.2 vs 65.5%, p = 0.044) and death or severe BPD (75.0 vs 47.6%, p = 0.003). Each day on NIPPV was associated with an increased risk of M-S BPD (OR 1.08, p < 0.001) and an increased risk of death or severe BPD (OR 1.03, p = 0.006). After adjusting for days on oxygen, ventilator days, and days on all respiratory support, the odds of developing M-S BPD increased by 4.9% for each additional week on NIPPV (CI 2.1-7.7%, p = .0001).

CONCLUSION

In this cohort, use of NIPPV was associated with an increased risk for developing BPD when compared to infants receiving nCPAP, and each additional day on NIPPV carried significant increased risk for developing BPD.

Application of Neurally Adjusted Ventilatory Assist in Premature Neonates Less Than 1,500 Grams With Established or Evolving Bronchopulmonary Dysplasia

Background: Very low birth weight premature (VLBW) infants with bronchopulmonary dysplasia (BPD) often need prolonged respiratory support, which is associated with worse outcomes. The application of neurally adjusted ventilatory assist ventilation (NAVA) in infants with BPD has rarely been reported. This study investigated whether NAVA is safe and can reduce the duration respiratory support in VLBW premature infants with established or evolving BPD. Methods: This retrospective matched-cohort study included patients admitted to our NICU between April 2017 to April 2019 who were born at <32 weeks' gestation with birthweight of <1,500 g. The study groups (NAVA group) were infants who received NAVA ventilation as a sequel mode of ventilation after at least 2 weeks of traditional respiratory support after birth. The control group were preterm infants who required traditional respiratory support beyond first 2 weeks of life and were closely matched to the NAVA patients by gestational age and birthweight. The primary outcome was to compare the total duration of respiratory support between the NAVA group and the control group. The secondary outcomes were comparisons of duration of invasive and non-invasive support, oxygen therapy, length of stay, severity of BPD, weight gain and sedation need between the groups. Results: There were no significant differences between NAVA group and control group in the primary and most of the secondary outcomes (all P > 0.05). However, NAVA was well tolerated and there was a decrease in the need of sedation (p = 0.012) after switching to NAVA. Conclusion: NAVA, when used as a sequel mode of ventilation, in premature neonates <1,500 g with evolving or established BPD showed a similar effect compared to conventional ventilation in respiratory outcomes. NAVA can be safely used in this patient population and potentially can decrease the need of sedation.

Proportional assist ventilation (PAV) versus neurally adjusted ventilator assist (NAVA): effect on oxygenation in infants with evolving or established bronchopulmonary dysplasia

Both proportional assist ventilation (PAV) and neurally adjusted ventilatory assist (NAVA) provide pressure support synchronised throughout the respiratory cycle proportional to the patient's respiratory demand. Our aim was to compare the effect of these two modes on oxygenation in infants with evolving or established bronchopulmonary dysplasia. Two-hour periods of PAV and NAVA were delivered in random order to 18 infants born less than 32 weeks of gestation. Quasi oxygenation indices ("OI") and alveolar-arterial ("A-a") oxygen gradients at the end of each period on PAV, NAVA and baseline ventilation were calculated using capillary blood samples. The mean "OI" was not significantly different on PAV compared to NAVA (7.8 (standard deviation (SD) 3.2) versus 8.1 (SD 3.4), respectively, p = 0.70, but lower on both than on baseline ventilation (mean baseline "OI" 11.0 (SD 5.0)), p = 0.002, 0.004, respectively). The "A-a" oxygen gradient was higher on PAV and baseline ventilation than on NAVA (20.8 (SD 12.3) and 22.9 (SD 11.8) versus 18.5 (SD 10.8) kPa, p = 0.015, < 0.001, respectively).Conclusion: Both NAVA and PAV improved oxygenation compared to conventional ventilation. There was no significant difference in the mean "OI" between the two modes, but the mean "A-a" gradient was better on NAVA.What is Known:• Proportional assist ventilation (PAV) and neurally adjusted ventilatory assist (NAVA) can improve the oxygenation index (OI) in prematurely born infants.• Both PAV and NAVA can provide support proportional to respiratory drive or demand throughout the respiratory cycle.What is New:• In infants with evolving or established BPD, using capillary blood samples, both PAV and NAVA compared to baseline ventilation resulted in improvement in the "OI", but there was no significant difference in the "OI" on PAV compared to NAVA.• The "alveolar-arterial" oxygen gradient was better on NAVA compared to PAV.

Protocolized Versus Nonprotocolized Weaning to Reduce the Duration of Invasive Mechanical Weaning in Neonates: A Systematic Review of All Types of Studies

Mechanical ventilation is one of the most commonly used treatments in neonatology. Prolonged mechanical ventilation is associated with deleterious outcomes. To reduce the ventilation duration, weaning protocols have been developed to achieve extubation in adult and pediatric care in a safe and uniform manner. We performed a systematic review to obtain all available evidence on the effect of protocolized versus nonprotocolized weaning on the duration of invasive mechanical ventilation in critically ill neonates. The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CINAHL, Web of Science, and the International Clinical Trial Registry Platform were searched until January 2018. Quantitative and qualitative studies involving neonates that investigated or described protocolized versus nonprotocolized weaning were included. Primary outcome was the difference in weaning duration. A total of 2099 potentially relevant articles were retrieved. Three studies met the inclusion criteria. Of 2 of these, the separate neonatal data could not be obtained. Only one retrospective study was included for this review. This reported a decrease in the mean weaning time from 18 to 5 and 6 days, respectively. There is no robust evidence in the literature to support or disprove the use of a weaning protocol in critically ill neonates.

Is noninvasive neurally adjusted ventilatory assistance (NIV-NAVA) an alternative to NCPAP in preventing extubation failure in preterm infants?

Background: Prolonged use of mechanical ventilation is associated with some complications as high mortality and high morbidities as bronchopulmonary dysplasia, ventilator-associated pneumonia, and pneumothorax. However, extubation failure in preterm infants is still high (40-60%) in very low birth weight infants (VLBW). Noninvasive neurally adjusted ventilatory assistance (NIV-NAVA) is triggered by the diaphragmatic electrical activity through a nasogastric tube that synchronizes patient/ventilator respiration, cycle by cycle effectively shortening the assisted cycle trigger and the degree of ventilatory assistance, optimizing the effects of intermittent inspiratory pressure on nasal continuous positive airway pressure (NCPAP). This study aims to compare reintubation rates until 72 h after extubation in preterm infants of high risk for reintubation using NIV-NAVA or NCPAP. Methods: A retrospective study of chart review data collection was performed in a private tertiary hospital. The study was approved by the local institutional Ethics Committee. We included infants considered at high risk of reintubation (BW < 1000 grams; use of invasive mechanical ventilation (IMV) for at least 7 days; or previous extubation failure episode) and compared the two groups according to the type of respiratory support after extubation: 1) NCPAP (n = 32); or 2) NIV-NAVA (n = 17). Demographics data were collected, the primary outcome was reintubation rate until 72 h after extubation. Secondary outcome was time to reintubation, BPD rate, IVH grade ≥ III, pneumothorax and death. Results: There was no difference between both groups in demographic data. The reintubation rate decreased significantly in the NIV-NAVA group compared to NCPAP (50.0-11.7, p < 0.02) despite the significantly higher length of invasive mechanical ventilation (IMV) before extubation attempt in NIV-NAVA group (12.4 versus 5.5 days, p < 0.04). There was no difference between both groups in secondary outcomes. Conclusions: In this small retrospective cohort study, the use of NIV-NAVA as postextubation strategy was effective in reducing extubation failure within 72 hours in preterm infants when compared to traditional NCPAP.

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.

Comparison of NIV-NAVA and NCPAP in facilitating extubation for very preterm infants

Background

Various types of noninvasive respiratory modalities that lead to successful extubation in preterm infants have been explored. We aimed to compare noninvasive neurally adjusted ventilatory assist (NIV-NAVA) and nasal continuous positive airway pressure (NCPAP) for the postextubation stabilization of preterm infants.

Methods

This retrospective study was divided into two distinct periods, between July 2012 and June 2013 and between July 2013 and June 2014, because NIV-NAVA was applied beginning in July 2013. Preterm infants of less than 30 weeks GA who had been intubated with mechanical ventilation for longer than 24 h and were weaned to NCPAP or NIV-NAVA after extubation were enrolled. Ventilatory variables and extubation failure were compared after weaning to NCPAP or NIV-NAVA. Extubation failure was defined when infants were reintubated within 72 h of extubation.

Results

There were 14 infants who were weaned to NCPAP during Period I, and 2 infants and 16 infants were weaned to NCPAP and NIV-NAVA, respectively, during Period II. At the time of extubation, there were no differences in the respiratory severity score (NIV-NAVA 1.65 vs. NCPAP 1.95), oxygen saturation index (1.70 vs. 2.09) and steroid use before extubation. Several ventilation parameters at extubation, such as the mean airway pressure, positive end-expiratory pressure, peak inspiratory pressure, and FiO₂, were similar between the two groups. SpO₂ and pCO₂ preceding extubation were comparable. Extubation failure within 72 h after extubation was observed in 6.3% of the NIV-NAVA group and 37.5% of the NCPAP group (P = 0.041).

Conclusions

The data in the present showed promising implications for using NIV-NAVA over NCPAP to facilitate extubation.

Current insights in non-invasive ventilation for the treatment of neonatal respiratory disease

Deleterious consequences of the management of respiratory distress syndrome (RDS) with invasive ventilation have led to more in-depth investigation of non-invasive ventilation (NIV) modalities. NIV has significantly and positively altered the treatment outcomes and improved mortality rates of preterm infants with RDS. Among the different NIV modes, nasal intermittent positive pressure ventilation (NIPPV) has shown considerable benefits compared to nasal continuous positive airway pressure (NCPAP). Despite reports of heated humidified high-flow nasal cannula’s (HHHFNC) non-inferiority compared to NCPAP, some trials have been terminated due to high treatment failure rates with HHHFNC use. Moreover, RDS management with the combination of INSURE (INtubation SURfactant Extubation) technique and NIV ensures higher success rates. This review elaborates on the currently used various modes of NIV and novel techniques are also briefly discussed.

Neural feedback is insufficient in preterm infants during neurally adjusted ventilatory assist

OBJECTIVES

To investigate the effects of changing assistance levels on respiratory patterns, including peak inspiratory pressure (PIP), overassistance, work of breathing, and discomfort in preterm infants during neurally adjusted ventilatory assist (NAVA).

WORKING HYPOTHESIS

Once the lungs reach optimal inflation, negative feedback suppresses neural respiratory drive and therefore, the electrical activity of the diaphragm (Edi) such that the lungs are protected from overinflation and breathing work is reduced.

STUDY DESIGN

A prospective study was conducted in 14 preterm infants (median postconceptional age of 32.1 weeks) who received at least 24 hours of ventilatory support for respiratory distress.

METHODOLOGY

Increasing and decreasing NAVA levels (from 0.5 to 4.0 cmH₂ O/µV with an interval of 0.5 cmH ₂ O/µV) were applied for 10 minutes each. Data recorded for the last 5 minutes of each NAVA level were analyzed. Heart rate and oxygen saturation were recorded and premature infant pain profiles were calculated.

RESULTS

An inflection point for PIP was not evident during increasing and decreasing assistance. Increasing NAVA levels caused greater variability in PIP and a higher proportion of the excessive tidal volume of more than 10 mL/kg. Peak Edi and discomfort scale decreased shortly after a small change in NAVA levels during increasing assistance. However, during decreasing assistance, peak Edi and discomfort scale remained low until a large reduction in NAVA levels.

CONCLUSION

Although NAVA can effectively alleviate the respiratory muscle work and discomfort, the neural feedback for protection from lung overinflation seems to be insufficient in preterm infants.

High continuous positive airway pressure in neonates: A physiological study

OBJECTIVE

We sought to evaluate physiological cardiorespiratory implications of high pressures (>8 cmH₂ O) on continuous positive airway pressure (CPAP) in preterm neonates.

METHODS

Fifteen preterm neonates at postmenstrual age ≥32 weeks on CPAP 5 cmH₂ O were enrolled. Pressures were increased by 2 cmH ₂ O increments until 13 cmH ₂ O. At each increment, cardiac output, electrical diaphragmatic (Edi) activity, and clinical cardiorespiratory parameters were measured. Predefined cut-off values for changes in cardiorespiratory parameters were used as termination criteria. Data, presented as mean (SD), were compared using repeated measures analysis of variance.

RESULTS

The mean GA, age at study, and weight of subjects were 27.4 (2.6) weeks, 58.5 (35.5) days, and 2.3 (0.6) kg, respectively. The median (IQR) time at each CPAP increment was 10 (5, 20) min. Cardiac output (mL/kg/min) at 5, 7, 9, 11, and 13 cmH ₂ O were not different at 295 (75), 290 (66), 281 (69), 286 (73), and 292 (58), respectively (P = 0.99). Edi values demonstrated a trend towards decline at 9 cmH ₂ O before rising again. No other cardiorespiratory parameter was different across CPAP levels; no subject met termination criteria.

CONCLUSION

High CPAP levels were well tolerated for short durations. Further physiological and clinical research is required on safety/efficacy in neonates with more severe lung disease, as well as its impact over longer durations.

Neurally adjusted ventilatory assist in extremely low-birthweight infants

BACKGROUND

Neurally adjusted ventilatory assist (NAVA) is expected to improve respiratory outcomes in preterm infants, but it has not yet been evaluated. We investigated whether NAVA could improve respiratory outcomes and reduce sedation use in extremely low-birthweight infants (ELBWI).

METHODS

A retrospective cohort study was conducted based on patient charts at the Nagano Children's Hospital neonatal intensive care unit, Japan. Infants who were born at <27 weeks' gestation were included. We assessed the prevalence of bronchopulmonary dysplasia (BPD), home oxygen therapy (HOT), duration of intubation, and sedation use.

RESULTS

The NAVA group consisted of 14 ELBWI who were born at <27 weeks' gestation between September 2013 and September 2015. A total of 21 ELBWI born between September 2011 and September 2013, before NAVA implementation, served as the control group. There were no significant differences in the perinatal background characteristics between the two groups. For respiratory outcomes, no significant between-group differences were found in the prevalence of BPD and HOT or the duration of intubation. The total duration of sedation use was not significantly different between the two groups, but in the NAVA group, midazolam was discontinued in all cases after the infants were switched to NAVA.

CONCLUSIONS

NAVA was safe in preterm infants and had a similar effect to conventional mechanical ventilation with regard to respiratory outcomes and sedation use in the chronic phase; thus, NAVA could be used in the early phase, at least before BPD worsens to improve respiratory outcomes in ELBWI.

Preventing Continuous Positive Airway Pressure Failure: Evidence-Based and Physiologically Sound Practices from Delivery Room to the Neonatal Intensive Care Unit

Routine use of continuous positive airway pressure (CPAP) to support preterm infants with respiratory distress is an evidenced-based strategy to decrease incidence of bronchopulmonary dysplasia. However, rates of CPAP failure remain unacceptably high in very premature neonates, who are at high risk for developing bronchopulmonary dysplasia. Using the GRADE framework to assess the quality of available evidence, this article reviews strategies aimed at decreasing CPAP failure, starting with delivery room interventions and followed through to system-based efforts in the neonatal intensive care unit. Despite best efforts, some very premature neonates fail CPAP. Also reviewed are predictors of CPAP failure in this vulnerable population.

The impact of neurally adjusted ventilatory assist mode on respiratory severity score and energy expenditure in infants: a randomized crossover trial

OBJECTIVE

Examine respiratory severity scores (RSS) (mean airway pressure × fraction of inspired oxygen) and resting energy expenditure (REE) on neurally adjusted ventilatory assist (NAVA) compared with synchronized intermittent mandatory ventilation with pressure controlled and supported breath (SIMV (PC)PS).

STUDY DESIGN

A randomized, crossover trial in a level IV neonatal intensive care unit. Twenty-four patients were ventilated with NAVA or SIMV (PC) PS for 12 h and then crossed over to the alternative mode for 12 h. The primary outcome (RSS) and additional secondary respiratory outcomes were analyzed.

RESULTS

RSS and measured REE were not different between modes. On NAVA, peak inspiratory pressures were lower (17.8 vs 19.9 cmH₂O (P<0.05)) without higher oxygen requirements. Respiratory rates were higher on NAVA (52 vs 39 (P<0.05)), estimated work of breathing (WOB) (0.01 vs 0.04 J l^-1 (P<0.05)) was improved.

CONCLUSION

NAVA mode can be safe without increase in RSS or REE. Although respiratory rates were higher, this was offset by lower peak inspiratory pressures and WOB during NAVA.

Neuromuscular disorders and chronic ventilation

Morbidity and mortality have decreased in patients with neuromuscular disease due to implementation of therapies to augment cough and improve ventilation. Infants with progressive neuromuscular disease will eventually develop respiratory complications as a result of muscle weakness and their inability to compensate during periods of increased respiratory loads. The finding of nocturnal hypercapnia is often the trigger for initiating non-invasive ventilation and studies have shown that its use not only may improve sleep-disordered breathing, but also that it may have an effect on daytime function, symptoms related to hypercapnia, and partial pressure of CO₂. It is important to understand the respiratory physiology of this population and to understand the benefits and limitations of assisted ventilation.

Physiology of non-invasive respiratory support

Non-invasive ventilation (NIV) is used in neonates to treat extrathoracic and intrathoracic airway obstruction, parenchymal lung disease and disorders of control of breathing. Avoidance of airway intubation is associated with a reduction in the incidence of chronic lung disease among preterm infants with respiratory distress syndrome. Use of nasal continuous positive airway pressure (nCPAP) may help establish and maintain functional residual capacity (FRC), decrease respiratory work, and improve gas exchange. Other modes of non-invasive ventilation, which include heated humidified high-flow nasal cannula therapy (HHHFNC), nasal intermittent mandatory ventilation (NIMV), non-invasive pressure support ventilation (NI-PSV), and bi-level CPAP (SiPAP™), have also been shown to provide additional benefit in improving breathing patterns, reducing work of breathing, and increasing gas exchange when compared with nCPAP. Newer modes, such as neurally adjusted ventilatory assist (NAVA), hold the promise of improving patient-ventilator synchrony and so might ultimately improve outcomes for preterm infants with respiratory distress.

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.

Electrical activity of the diaphragm during neurally adjusted ventilatory assist in pediatric patients

BACKGROUND

Neurally adjusted ventilatory assist (NAVA) is a ventilation mode which provides respiratory support proportional to the electrical activity of the diaphragm (Edi). The aims of this trial were to assess the feasibility of aiming at peak Edi between 5 and 15 µV during NAVA in clinical practice, to study the effect of age, sedation level and ventilatory settings on the Edi signal and to give some reference values for Edi in a pediatric population.

METHODS

As a part of a larger randomized controlled trial, 81 patients received Edi catheter for monitoring Edi and guiding NAVA ventilation. The goal for peak Edi during invasive ventilation was 5-15 µV. Edi activity and NAVA levels were observed during invasive ventilation and an hour after extubation.

RESULTS

Sixty-six patients with healthy lungs (81.5%) were ventilated, mostly as part of postoperative care, while respiratory distress was the indication for invasive ventilation in the remaining 15 patients (18.5%). NAVA levels varied from 0.2 to 2.0 cmH2O/µV in the patients with healthy lungs, but were higher, from 0.7 to 4.0 cmH2O/µV, in the respiratory distress patients (P < 0.001). The latter had higher peak Edi values in all phases of treatment. The effect of age and level of sedation on Edi was statistically significant, but carried only limited clinical relevance. The peak post-extubation Edi levels of the patients with healthy lungs and respiratory distress, respectively, were 9 ± 7 and 20 ± 14 µV. Two out of the three patients for whom extubation failed had an atypical Edi pattern prior to extubation.

CONCLUSIONS

Optimizing the level of support during NAVA by aiming at a peak Edi between 5 and 15 µV was an applicable strategy in our pediatric population. Relatively high post-extubation Edi signal levels were seen in patients recovering from respiratory distress. Information revealed by the Edi signal could be used to find patients with a potential risk of extubation failure.

Current concepts in acute respiratory support for neonates and children

Current trends in mechanical respiratory support are evolving toward gentle approaches to avoid short- and long-term problems that are historically associated with mechanical ventilation. These ventilator-associated issues include the need for long-term sedation, muscle deconditioning, ventilator-associated lung injury (VALI), and ventilator-associated pneumonia (VAP). This article will describe recent trends of ventilatory support in neonates and children: (1) utilization of volume ventilation in infants, (2) synchrony and improving patient-ventilator interaction specifically using neurally adjusted ventilatory assist (NAVA), and (3) use of noninvasive ventilation techniques. When applicable, their uses in the surgical newborn and pediatric patients are described.

Is synchronised NIPPV more effective than NIPPV and NCPAP in treating apnoea of prematurity (AOP)? A randomised cross-over trial

BACKGROUND

Apnoea, desaturations and bradycardias are common problems in preterm infants which can be treated with nasal continuous positive airway pressure (NCPAP) and nasal intermittent positive pressure ventilation (NIPPV). It is unclear whether synchronised NIPPV (SNIPPV) would be even more effective.

OBJECTIVE

To assess the effects of flow-SNIPPV, NIPPV and NCPAP on the rate of desaturations and bradycardias in preterm infants and, secondarily, to evaluate their influence on pattern of breathing and gas exchange.

PATIENTS AND METHODS

Nineteen infants (mean gestational age at study 30 weeks, 9 boys) with apnoeic spells were enrolled in a randomised controlled trial with a cross-over design. They received flow-SNIPPV, NIPPV and NCPAP for 4 h each. All modes were provided by a nasal conventional ventilator able to provide synchronisation by a pneumotachograph. The primary outcome was the event rate of desaturations (≤80% arterial oxygen saturation) and bradycardias (≤80 bpm) per hour, obtained from cardiorespiratory recordings. The incidence of central apnoeas (≥10 s) as well as baseline heart rate, FiO2, SpO2, transcutaneous blood gases and respiratory rate were also evaluated.

RESULTS

The median event rate per hour during flow-SNIPPV, NIPPV and NCPAP was 2.9, 6.1 and 5.9, respectively (p<0.001 and 0.009, compared with flow-SNIPPV). Central apnoeas per hour were 2.4, 6.3 and 5.4, respectively (p=0.001, for both compared with flow-SNIPPV), while no differences in any other parameter studied were recorded.

CONCLUSIONS

Flow-SNIPPV seems more effective than NIPPV and NCPAP in reducing the incidence of desaturations, bradycardias and central apnoea episodes in preterm infants.