Neural Breathing Pattern and Patient-Ventilator Interaction During Neurally Adjusted Ventilatory Assist and Conventional Ventilation in Newborns

Neurally Adjusted Ventilatory Assist to Monitor Diaphragmatic Activity in Infantile Botulism

Infantile botulism is a potentially life-threatening neuromuscular disorder. It presents with descending paralysis that can involve the diaphragm and cause respiratory failure. Neurally adjusted ventilatory assist (NAVA) provides synchronized bilevel positive pressure by using electrical diaphragmatic (Edi) signals. Diaphragmatic paresis is thought to be a contraindication for using NAVA. However, the use of a NAVA catheter allows continuous assessment of diaphragm activity in infantile botulism. We discuss a case of infantile botulism in an infant from central Pennsylvania who presented with poor oral feeding, hypothermia, and lethargy and progressed to develop apnea and acute respiratory failure. The infant was intubated and mechanically ventilated. A diagnosis of infantile botulism was confirmed through the detection of botulinum toxin in the infant's stool, and the infant was treated with botulism immune globulin neutralizing antibodies. During his recovery phase, a NAVA catheter was placed, which allowed monitoring of Edi signals to gauge the return of diaphragm activity and to assist with the assessment of extubation readiness. We describe the trends in this infant's Edi signals following administration of globulin neutralizing antibodies and the successful transition to invasive, and subsequently, noninvasive NAVA. Our report demonstrates the clinical utility of monitoring diaphragmatic activity using a NAVA catheter and that NAVA provided adequate respiratory support to an infant during the recovery phase of infantile botulism.

Detection and quantitative analysis of patient-ventilator interactions in ventilated infants by deep learning networks

BACKGROUND

The study of patient-ventilator interactions (PVI) in mechanically ventilated neonates is limited by the lack of unified PVI definitions and tools to perform large scale analyses.

METHODS

An observational study was conducted in 23 babies randomly selected from 170 neonates who were ventilated with SIPPV-VG, SIMV-VG or PSV-VG mode for at least 12 h. 500 breaths were randomly selected and manually annotated from each recording to train convolutional neural network (CNN) models for PVI classification.

RESULTS

The average asynchrony index (AI) over all recordings was 52.5%. The most frequently occurring PVIs included expiratory work (median: 28.4%, interquartile range: 23.2-40.2%), late cycling (7.6%, 2.8-10.2%), failed triggering (4.6%, 1.2-6.2%) and late triggering (4.4%, 2.8-7.4%). Approximately 25% of breaths with a PVI had two or more PVIs occurring simultaneously. Binary CNN classifiers were developed for PVIs affecting ≥1% of all breaths (n = 7) and they achieved F1 scores of >0.9 on the test set except for early triggering where it was 0.809.

CONCLUSIONS

PVIs occur frequently in neonates undergoing conventional mechanical ventilation with a significant proportion of breaths containing multiple PVIs. We have developed computational models for seven different PVIs to facilitate automated detection and further evaluation of their clinical significance in neonates.

IMPACT

The study of patient-ventilator interactions (PVI) in mechanically ventilated neonates is limited by the lack of unified PVI definitions and tools to perform large scale analyses. By adapting a recent taxonomy of PVI definitions in adults, we have manually annotated neonatal ventilator waveforms to determine prevalence and co-occurrence of neonatal PVIs. We have also developed binary deep learning classifiers for common PVIs to facilitate their automatic detection and quantification.

Neurally adjusted ventilatory assist improves survival, and its early application accelerates weaning in preterm infants

BACKGROUND

Evidence to show that neurally adjusted ventilatory assist (NAVA) improves clinical outcomes is lacking. We aimed to analyze whether NAVA improves respiratory outcomes in preterm infants who require invasive mechanical ventilation.

METHODS

A retrospective cohort study was conducted in 122 very low birthweight infants who required invasive mechanical ventilation for more than 24 h at one tertiary neonatal intensive care unit in Korea from January 2016 to June 2023. Subjects were divided into three groups: early NAVA for those supported with NAVA before the seventh day of life (n = 18), late NAVA for those supported with NAVA later than the seventh day (n = 18), and conventional for those supported with conventional ventilation modes other than NAVA (n = 86).

RESULTS

There was no difference in the composite outcome of bronchopulmonary dysplasia or death among the three groups. Neonates who had been supported with NAVA at some point had lower odds of mortality than those who had not (adjusted odds ratio [aOR] 0.09, 95% CI 0.01-0.90, p = 0.040 for the early NAVA group; aOR 0.15, 95% CI 0.03-0.81, p = 0.027 for the late NAVA group). The adjusted hazard ratio for invasive mechanical ventilation weaning was higher in neonates supported with NAVA within the first week of life than in those supported with other ventilation modes (aHR 2.02, 95% CI 1.14-3.57, p = 0.015).

CONCLUSIONS

Neurally adjusted ventilatory assist application was associated with lower odds of mortality, and its early application from the first few days of life helped preterm infants wean from invasive mechanical ventilation sooner.

Evaluation of NAVA-PAP in premature neonates with apnea of prematurity: minimal backup ventilation and clinically significant events

Background

Neonates with apnea of prematurity (AOP) clinically deteriorate because continuous positive airway pressure (CPAP) provides inadequate support during apnea. Neurally adjusted ventilatory assist (NAVA) provides proportional ventilator support from the electrical activity of the diaphragm. When the NAVA level is 0 cmH2O/mcV (NAVA-PAP), patients receive CPAP when breathing and backup ventilation when apneic. This study evaluates NAVA-PAP and time spent in backup ventilation.

Methods

This was a prospective, two-center, observational study of preterm neonates on NAVA-PAP for AOP. Ventilator data were downloaded after 24 h. The number of clinically significant events (CSEs) was collected. A paired t-test was used to perform statistical analysis.

Results

The study was conducted on 28 patients with a gestational age of 25 ± 1.8 weeks and a study age of 28 ± 23 days. The number of CSEs was 4 ± 4.39/24 h. The patients were on NAVA-PAP for approximately 90%/min, switched to backup mode 2.5 ± 1.1 times/min, and spent 10.6 ± 7.2% in backup.

Conclusion

Preterm neonates on NAVA-PAP had few CSEs with minimal time in backup ventilation.

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.

Clinical Characteristics of Mechanically Ventilated Patients Treated in Non-ICU Settings in a Rural Area of Japan

Introduction Patients requiring mechanical ventilation (MV) are commonly managed in an intensive care unit (ICU); however, Japan is unique in that many patients are treated in non-ICU settings. The characteristics of these patients, nevertheless, are unknown. We sought to identify disease severity and MV settings of patients in non-ICU. Methods We retrospectively analyzed the clinical data of Kinan Hospital and Owase General Hospital, where there are no ICUs. Data for adult patients who required MV from January through December 2018 were collected. To find the characteristics of patients who have been decided to treat in non-ICU hospitals without early transferring, we analyzed patients who have been treated for more than three days in those hospitals. Results A total of 171 patients received MV; 29 patients were treated for more than three days. Of those, the mortality rate was 44.8% (13 patients). The median age was 80 years (range: 72-84 years). The mean Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II) score was 20.9 ± 8.1, and predicted mortality was 0.42 ± 0.25. Tidal volume per predicted body weight was 8.8 ± 2.1 mL/kg, and set inspiratory time was 1.6 ± 0.3 seconds. Conclusions We have first described the severity and the initial ventilator setting of MV patients treated for more than three days in non-ICU setting in Japan. The overall predicted mortality was 42%, and the average age of the patients was 80 years. Further research on wider areas and the comparison to the patients treated in ICUs are needed to identify the appropriateness of treating patients in non-ICU settings.

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.

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.

Evaluating peak inspiratory pressures and tidal volume in premature neonates on NAVA ventilation

Neurally adjusted ventilatory assist (NAVA) ventilation allows patients to determine their peak inspiratory pressure and tidal volume on a breath-by-breath basis. Apprehension exists about premature neonates' ability to self-regulate breath size. This study describes peak pressure and tidal volume distribution of neonates on NAVA and non-invasive NAVA. This is a retrospective study of stored ventilator data with exploratory analysis. Summary statistics were calculated. Distributional assessment of peak pressure and tidal volume were evaluated, overall and per NAVA level. Over 1 million breaths were evaluated from 56 subjects. Mean peak pressure was 16.4 ± 6.4 in the NAVA group, and 15.8 ± 6.4 in the NIV-NAVA group (t test, p < 0.001). Mean tidal volume was 3.5 ± 2.7 ml/kg.Conclusion:In neonates on NAVA, most pressures and volumes were within or lower than recommended ranges with pressure-limited or volume-guarantee ventilation. What is known: • Limiting peak inspiratory pressures or tidal volumes are the main strategies to minimize ventilator-induced lung injury in neonates. Neurally adjusted ventilatory assist allows neonates to regulate their own peak inspiratory pressures and tidal volumes on a breath-to-breath basis using neural feedback. What is new: • When neonates chose the size of their breaths based on neural feedback, the majority of peak inspiratory pressures and tidal volumes were within or lower than the recommended peak inspiratory pressure or tidal volume ranges with pressure-limited or volume guarantee ventilation.

Neurally adjusted ventilatory assist versus conventional ventilation in the pediatric population: Are there benefits?

INTRODUCTION

Neurally-adjusted ventilator assist (NAVA) is a relatively new form of ventilation in which the electrical activity of the diaphragm is sensed by a catheter. The amplitude of this electrical signal is then used to deliver an appropriately proportioned pressure supported breath to the patient. Due to the synchronous nature of the breaths and the patient-adjusted nature of the support, NAVA has been shown to have benefits over conventional ventilation. Meta-analyses were conducted of published pediatric studies to compare ventilatory endpoints between NAVA and conventional ventilation.

METHODS

Studies comparing ventilatory parameters between NAVA and conventional ventilation in pediatric patients were identified. These studies were reviewed for appropriateness for inclusion and studies of only pediatric patients with data for similar endpoints between both arms were then pooled.

RESULTS

Statistically significant differences were noted in asynchrony, peak inspiratory pressure (PIP), and oxygen saturation by pulse oximetry. Asynchrony was 17% lower with NAVA, PIP was 1.74 cmH₂ 0 lower with NAVA, and oxygen saturation was 1.1% greater with NAVA. There was no statistically significant difference in peak expiratory pressure, mean airway pressure, electrical diaphragmatic activity, respiratory rate, hydrogen ion concentration, partial pressure of oxygen, or partial pressure of carbon dioxide.

CONCLUSION

Statistically significant differences were noted in percent asynchrony, PIP, and oxygen saturation when comparing NAVA to conventional ventilation. These all tended to favor NAVA. Other than percent asynchrony, however, the other statistically significant findings were not clinically significant.

Neural breathing patterns in preterm newborns supported with non-invasive neurally adjusted ventilatory assist

OBJECTIVE

To characterize the neural breathing pattern in preterm infants supported with non-invasive neurally adjusted ventilatory assist (NIV-NAVA).

STUDY DESIGN

Single-center prospective observational study. The electrical activity of the diaphragm (EAdi) was periodically recorded in 30-second series with the Edi catheter and the Servo-n software (Maquet, Solna, Sweden) in preterm infants supported with NIV-NAVA. The EAdi_Peak, EAdi_Min, EAdi_Tonic, EAdi_Phasic, neural inspiratory, and expiratory times (nTi and nTe) and the neural respiratory rate (nRR) were calculated. EAdi curves were generated by Excel for visual examination and classified according to the predominant pattern.

RESULTS

291 observations were analyzed in 19 patients with a mean GA of 27.3 weeks (range 24-36 weeks), birth weight 1028 g (510-2945 g), and a median (IQR) postnatal age of 18 days (4-27 days). The distribution of respiratory patterns was phasic without tonic activity 61.9%, phasic with basal tonic activity 18.6, tonic burst 3.8%, central apnea 7.9%, and mixed pattern 7.9%. In addition, 12% of the records showed apneas of >10 seconds, and 50.2% one or more "sighs", defined as breaths with an EAdi_Peak and/or nTi greater than twice the average EAdi_Peak and/or nTi of the recording. Neural times were measurable in 252 observations. The nTi was, median (IQR): 279 ms (253-285 ms), the nTe 764 ms (642-925 ms), and the nRR 63 bpm (51-70), with a great intra and inter-subjects variability.

CONCLUSIONS

The neural breathing patterns in preterm infants supported with NIV-NAVA are quite variable and are characterized by the presence of significant tonic activity. Central apneas and sighs are common in this group of patients. The nTi seems to be shorter than the mechanical Ti commonly used in assisted ventilation.