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

Non-invasive neurally adjusted ventilatory assist (NIV-NAVA) in the neonatal intensive care unit (NICU): an Australian NICU experience

BACKGROUND

Preterm infants often require non-invasive breathing support while their lungs and control of respiration are still developing. Non-invasive neurally adjusted ventilatory assist (NIV-NAVA) is an emerging technology that allows infants to breathe spontaneously while receiving support breaths proportional to their effort. This study describes the first Australian Neonatal Intensive Care Unit (NICU) experience of NIV-NAVA.

METHODS

Retrospective cohort study of infants admitted to a major tertiary NICU between October 2017 and April 2021 supported with NIV-NAVA. Infants were divided into three groups based on the indication to initiate NIV-NAVA (post-extubation; apnoea; escalation). Successful application of NIV-NAVA was based on the need for re-intubation within 48 h of application.

RESULTS

There were 169 NIV-NAVA episodes in 122 infants (82 post-extubation; 21 apnoea; 66 escalation). The median (range) gestational age at birth was 25 + 5 weeks (23 + 1 to 43 + 3 weeks) and median (range) birthweight was 963 g (365-4320 g). At NIV-NAVA application, mean (SD) age was 17 days (18.2), and median (range) weight was 850 g (501-4310 g). Infants did not require intubation within 48 h in 145/169 (85.2%) episodes [72/82 (87.8%) extubation; 21/21 (100%) apnoea; 52/66 (78.8%) escalation).

CONCLUSION

NIV-NAVA was successfully integrated for the three main indications (escalation; post-extubation; apnoea). Prospective clinical trials are still required to establish its effectiveness versus other modes of non-invasive support.

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.

Case Report: Neurally adjusted ventilatory assist as an effective rescue treatment for pulmonary interstitial emphysema in extremely low birth weight infants

Pulmonary interstitial emphysema (PIE) is a complication observed in extremely low birth weight (ELBW) infants on mechanical ventilation. Despite various proposed therapeutic interventions, the success rates have shown inconsistency. Neurally adjusted ventilatory assist (NAVA) stands out as a novel respiratory support mode, offering lower pressure and tidal volume in comparison to conventional ventilation methods. In this case report, we present five ELBW infants with refractory PIE who were transitioned to NAVA ventilation. Following the switch to NAVA, all cases of PIE gradually resolved. In contrast to traditional modes, NAVA provided respiratory support with significantly lower fraction of inspired oxygen, reduced peak inspiratory pressure, diminished mean airway pressure, and decreased tidal volume within 7 days of NAVA utilization (p = 0.042, 0.043, 0.043, and 0.042, respectively). Consequently, we propose that NAVA could serve as a valuable rescue treatment for ELBW infants with PIE.

Invasive and non-invasive ventilatory strategies for early and evolving bronchopulmonary dysplasia

In the age of surfactant and antenatal steroids, neonatal care has improved outcomes of preterm infants dramatically. Since the early 2000's neonatologists have strived to decrease bronchopulmonary dysplasia (BPD) by decreasing ventilator-associated lung injury and utilizing many novel modes of non-invasive respiratory support. After the initial success with nasal continuous positive airway pressure, it was established that discontinuing invasive ventilation early in favor of non-invasive respiratory support is the most effective way to reduce the incidence of BPD. In this review, we discuss the management of the preterm lung from the time of delivery, through the phases of respiratory distress syndrome (early BPD) and then evolving BPD. The goal remains to optimize respiratory support of the preterm lung while minimizing ventilator-associated lung injury and oxygen toxicity. A multidisciplinary approach involving the medical team and family is quintessential in reaching this goal and involves adequate respiratory support, optimizing nutrition and fluid balance as well as preventing infections.

Neonatal respiratory support strategies-short and long-term respiratory outcomes

Mechanical ventilation (MV), although life-saving, is associated with chronic respiratory morbidity in both preterm and term born infants. New ventilation modes have been developed with the aim of minimising lung injury. These include invasive and non-invasive respiratory support strategies, techniques for less invasive surfactant administration (LISA) and closed-loop automated oxygen control (CLAC) systems. Increasingly, newborn infants with signs of respiratory distress are stabilised on continuous positive airway pressure (CPAP) and receive LISA. Early CPAP when compared to mechanical ventilation reduced the incidence of BPD and respiratory morbidity at 18 to 22 months corrected age. Nasal intermittent positive pressure ventilation reduced treatment failure rates compared to CPAP, but not bronchopulmonary dysplasia (BPD). LISA compared with intubation and surfactant delivery reduced BPD, but there is no evidence from randomised trials regarding long-term respiratory and neurodevelopmental outcomes. Synchronisation of positive pressure inflations with the infant's respiratory efforts used with volume targeting should be applied for infants requiring intubation as this strategy reduces BPD. A large RCT with long term follow up data demonstrated that prophylactic high frequency oscillatory ventilation (HFOV) improved respiratory and functional outcomes at school age, but those effects were not maintained after puberty. CLAC systems appear promising, but their effect on long term clinical outcomes has not yet been explored in randomised trials. Further studies are required to determine the role of newer ventilation modes such as neurally adjusted ventilator assist (NAVA). All such respiratory support strategies should be tested in randomised controlled trials powered to assess long-term outcomes.

Neurally adjusted ventilatory assist in infants: A review article

Neurally adjusted ventilatory assist (NAVA) and non-invasive (NIV)-NAVA are innovative modes of synchronized and proportional respiratory support. They can synchronize with the patients' breathing and promote patient comfort. Both techniques are increasingly being used these years, however experience with their use in newborns and premature infants in Taiwan is relatively few. Because increasing evidence supports the use of NAVA and NIV-NAVA in newborns and premature infants requiring respiratory assist to achieve better synchrony, the aim of this article is to discuss whether NAVA can provide better synchronization and comfort for ventilated newborns and premature babies. In a review of recent literature, we found that NAVA and NIV-NAVA appear to be superior to conventional invasive and non-invasive ventilation. Nevertheless, some of the benefits are controversial. For example, treatment failure in premature infants is common due to insufficient triggering of electrical activity of the diaphragm (EAdi) and frequent apnea, highlighting the differences between premature infants and adults in settings and titration. Further, we suggest how to adjust the settings of NAVA and NIV-NAVA in premature infants to reduce clinical adverse events and extubation failure. In addition to assist in the use of NAVA, EAdi can also serve as a continuous and real-time monitor of vital signs, assisting physicians in the administration of sedatives, evaluation of successful extubation, and as a reference for the patient's respiratory condition during special procedures.

The use of neurally-adjusted ventilatory assist (NAVA) for infants with congenital diaphragmatic hernia (CDH)

OBJECTIVES

Newborns with congenital diaphragmatic hernia (CDH) can have complex respiratory problems which are worsened by ventilatory induced lung injury. Neurally adjusted ventilator assist (NAVA) is a potentially promising ventilation mode for this population, as it can result in improved patient-ventilator interactions and provision of adequate gas exchange at lower airway pressures.

CONTENT

A literature review was undertaken to provide an overview of NAVA and examine its role in the management of infants with CDH.

SUMMARY

NAVA in neonates has been used in CDH infants who were stable on ventilatory support or being weaned from mechanical ventilation and was associated with a reduction in the level of respiratory support.

OUTLOOK

There is, however, limited evidence regarding the efficacy of NAVA in infants with CDH, with only short-term benefits being investigated. A prospective, multicentre study with long term follow-up is required to appropriately assess NAVA in this population.

Pathophysiologically Based Ventilatory Management of Severe Bronchopulmonary Dysplasia

Both "new" and "old" bronchopulmonary dysplasia features overlap in preterm infants with severe bronchopulmonary dysplasia. The optimal ventilation strategy for infants with severe bronchopulmonary dysplasia has not been clarified yet. Principally, the lung is a multi-com- partmental heterogeneous tissue with regionally varying compliance and resistance. Generally, 2 critical strategical errors are common while ventilating infants with established bronchopulmonary dysplasia: (i) ventilatory management as if they are still in the acute phase of respiratory distress syndrome and (ii) early extubation attempts with the aim of reducing ventilator-induced lung injury. Considering the heterogeneous character of bronchopulmo- nary dysplasia, although there is no unique formulation for optimal ventilation, the most physi- ologically appropriate ventilation mode may be the combined mode of volume-guaranteed synchronized intermittent mechanical ventilation and pressure support ventilation. With the volume-guaranteed synchronized intermittent mechanical ventilation mode, slow compart- ments of the lung with high resistance and low compliance can be adequately ventilated, while fast compartments having relatively normal resistance and compliance can be venti- lated well with the pressure support ventilation mode. The following settings are advisable: frequency = 12-20 breaths per minute, tidal volume = 10-15 mL/min, positive end expiratory pressure = 7-12 cmH2O, and inspiratory to expiratory time ratio = 1 : 5. Higher oxygen satura- tions such as 92%-95% should be targeted to avoid subsequent pulmonary hypertension. In conclusion, there is no evidence-based ventilation recommendation for infants with severe bronchopulmonary dysplasia. However, given the changing pattern of the disease and the underlying pathophysiology, these infants should not be ventilated as if they were in the acute phase of respiratory distress syndrome.

Effect of doxapram on the electrical activity of the diaphragm waveform pattern of preterm infants

OBJECTIVE

This study aimed to evaluate the change in the waveform pattern of the electrical activity of the diaphragm (Edi) following the administration of doxapram in extremely preterm infants ventilated with neurally adjusted ventilatory assist (NAVA).

STUDY DESIGN

We conducted this retrospective cohort study in our neonatal intensive care unit between November 2019 and September 2021. The study participants were extremely preterm infants under the gestational age of 28 weeks who were ventilated with NAVA and administered doxapram. We collected the data of the Edi waveform pattern and calculated the proportion. To analyze the change in the proportion of the Edi waveform pattern, we compared the proportion of the data for 1 h before and after doxapram administration.

RESULTS

Ten extremely preterm infants were included. Almost all the patients' respiratory condition improved after doxapram administration. The ventilatory parameters-Edi peak, Edi minimum, peak inspiratory pressure, time in backup ventilation, and number of switches to backup ventilation-did not change significantly. However, the proportion of phasic pattern significantly increased (before: 46% vs. after: 72%; p < 0.05), whereas the central apnea pattern significantly decreased after doxapram administration (before: 31% vs. after: 8.3%; p < 0.05). The proportion of irregular low-voltage patterns tended to decrease, albeit with no significant changes.

CONCLUSION

Our results indicated that the proportion of Edi waveform patterns changed following doxapram administration. Edi waveform pattern analysis could be a sensitive indicator of effect with other intervention for respiratory conditions.

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.

Tracheostomy in infants with severe bronchopulmonary dysplasia: A review

In recent years, with increased survival of infants with severe bronchopulmonary dysplasia (BPD), long term ventilation due to severe BPD has increased and become the most common indication for tracheostomy in infants less than one year of age. Evidence shows that tracheostomy in severe BPD may improve short- and long-term respiratory and neurodevelopmental outcomes. However, there is significant variation among centers in the indication, timing, intensive care management, and follow-up care after hospital discharge of infants with severe BPD who received tracheostomy for chronic ventilation. The timing of liberation from the ventilator, odds of decannulation, rate of rehospitalization, growth, and neurodevelopment are all clinically important outcomes that can guide both clinicians and parents to make a well-informed decision when choosing tracheostomy and long-term assisted ventilation for infants with severe BPD. This review summarizes the current literature regarding the indications and timing of tracheostomy placement in infants with severe BPD, highlights center variability in both intensive care and outpatient follow-up settings, and describes outcomes of infants with severe BPD who received tracheostomy.

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.

Neurally Adjusted Ventilatory Assist in Newborns

Patient-ventilator asynchrony is very common in newborns. Achieving synchrony is quite challenging because of small tidal volumes, high respiratory rates, and the presence of leaks. Leaks also cause unreliable monitoring of respiratory metrics. In addition, ventilator adjustment must take into account that infants have strong vagal reflexes and demonstrate central apnea and periodic breathing, with a high variability in breathing pattern. Neurally adjusted ventilatory assist (NAVA) is a mode of ventilation whereby the timing and amount of ventilatory assist is controlled by the patient's own neural respiratory drive. As NAVA uses the diaphragm electrical activity (Edi) as the controller signal, it is possible to deliver synchronized assist, both invasively and noninvasively (NIV-NAVA), to follow the variability in breathing pattern, and to monitor patient respiratory drive, independent of leaks. This article provides an updated review of the physiology and the scientific literature pertaining to the use of NAVA in children (neonatal and pediatric age groups). Both the invasive NAVA and NIV-NAVA publications since 2016 are summarized, as well as the use of Edi monitoring. Overall, the use of NAVA and Edi monitoring is feasible and safe. Compared with conventional ventilation, NAVA improves patient-ventilator interaction, provides lower peak inspiratory pressure, and lowers oxygen requirements. Evidence from several studies suggests improved comfort, less sedation requirements, less apnea, and some trends toward reduced length of stay and more successful extubation.

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.

Effect of electrical activity of the diaphragm waveform patterns on SpO2 for extremely preterm infants ventilated with neurally adjusted ventilatory assist

OBJECTIVE

This study aimed to evaluate the association between electrical activity of the diaphragm (Edi) waveform patterns and peripheral oxygen saturation (SpO₂ ) in extremely preterm infants who are ventilated with neurally adjusted ventilatory assist (NAVA).

STUDY DESIGN

We conducted a retrospective cohort study at a level III neonatal intensive care unit. Extremely preterm infants born at our hospital between November 2019 and November 2020 and ventilated with NAVA were included. We collected Edi waveform data and classified them into four Edi waveform patterns, including the phasic pattern, central apnea pattern, irregular low-voltage pattern, and tonic burst pattern. We analyzed the Edi waveform pattern for the first 15 h of collectable data in each patient. To investigate the association between Edi waveform patterns and SpO₂ , we analyzed the dataset every 5 min as one data unit. We compared the proportion of each waveform pattern between the desaturation (Desat [+]) and non-desaturation (Desat [-]) groups.

RESULTS

We analyzed collected data for 105 h (1260 data units). The proportion of the phasic pattern in the Desat (+) group was significantly lower than that in the Desat (-) group (p < .001). However, the proportions of the central apnea, irregular low-voltage, and tonic burst patterns in the Desat (+) group were significantly higher than those in the Desat (-) group (all p < .05).

CONCLUSION

Our results indicate that proportions of Edi waveform patterns have an effect on desaturation of SpO₂ in extremely preterm infants who are ventilated with NAVA.

Development and Validation of a Nomogram for Predicting Bronchopulmonary Dysplasia in Very-Low-Birth-Weight Infants

Background: Bronchopulmonary dysplasia is a common pulmonary disease in newborns and is one of the main causes of death. The aim of this study was to build a new simple-to-use nomogram to screen high-risk populations. Methods: In this single-center retrospective study performed from January 2017 to December 2020, we reviewed data on very-low-birth-weight infants whose gestational ages were below 32 weeks. LASSO regression was used to select variables for the risk model. Then, we used multivariable logistic regression to build the prediction model incorporating these selected features. Discrimination was assessed by the C-index, and and calibration of the model was assessed by and calibration curve and the Hosmer-Lemeshow test. Results: The LASSO regression identified gestational age, duration of ventilation and serum NT-proBNP in the 1st week as significant predictors of BPD. The nomogram-illustrated model showed good discrimination and calibration. The C-index was 0.853 (95% CI: 0.851-0.854) in the training set and 0.855 (95% CI: 0.77-0.94) in the validation set. The calibration curve and Hosmer-Lemeshow test results showed good calibration between the predictions of the nomogram and the actual observations. Conclusion: We demonstrated a simple-to-use nomogram for predicting BPD in the early stage. It may help clinicians recognize high-risk populations.