Neuro-ventilatory efficiency during weaning from mechanical ventilation using neurally adjusted ventilatory assist

BACKGROUND

Neuro-ventilatory efficiency (NVE), defined as the tidal volume to electrical diaphragm-activity ratio (VT/EAdi) at the beginning and end of the weaning process after acute hypoxaemic respiratory failure, may provide valuable information about patient recovery.

METHODS

This observational study included 12 patients breathing with neurally adjusted ventilatory assist (NAVA). When a spontaneous breathing trial (SBT) with pressure support of 7 cm H2O and PEEP was unsuccessful, NAVA was used and the level was adjusted to obtain an EAdi of ∼60% of maximal EAdi during SBT. VT and EAdi were recorded continuously. We compared changes in NVE between NAVA and SBT at the first failed and first successful SBT.

RESULTS

When patients were switched from NAVA to SBT, NVE was significantly reduced during both unsuccessful and successful SBT (-56 and -38%, respectively); however, this reduction was significantly lower when SBT was successful (P=0.01). Between the first and last day of weaning, we observed that NVE decreased with NAVA [40.6 (27.7-89.5) vs 28.8 (18.6-46.7); P=0.002] with a significant decrease in NAVA level, whereas it remained unchanged during SBT [15.4 (10.7-39.1) vs 19.5 (11.6-29.6); P=0.50] with significant increases in both EAdi and VT and no difference in respiratory rhythm.

CONCLUSIONS

These results suggest that in patients after respiratory failure and prolonged mechanical ventilation, changes in VT and NVE, between SBTs are indicative of patient recovery. Larger clinical trials are needed to clarify whether changes in NVE reliably predict weaning in patients ventilated with NAVA.

Nasal continuous positive airway pressure (NCPAP) or noninvasive neurally adjusted ventilatory assist (NIV-NAVA) for preterm infants with respiratory distress after birth: A randomized controlled trial

OBJECTIVES

To compare rates of treatment failure between the use of nasal continuous positive airway pressure (NCPAP) and noninvasive neurally adjusted ventilatory assist (NIV-NAVA) in infants with respiratory distress after birth.

METHODS

A randomized, unblinded, double-center trial was conducted in infants with birth weights (BWs) less than or equal to 1500 g and respiratory distress receiving noninvasive respiratory support for less than or equal to 48 hours of life; some infants were initially treated with minimally invasive surfactant therapy as the standard of care.

PRIMARY OUTCOME

need for endotracheal intubation with use of mechanical ventilation (MV) at less than or equal to 72 hours of life using prespecified failure criteria.

SECONDARY OUTCOMES

use of surfactant, duration of noninvasive support, duration of MV, bronchopulmonary dysplasia (BPD) and death.

RESULTS

A total of 123 infants were included (NCPAP group = 64 and NIV-NAVA group = 59). Population characteristics were similar between groups. No difference in the primary outcome was observed: NCPAP = 10 (15.6%) and NIV-NAVA = 12 (20.3%), P = .65. Groups were also similar in the use of surfactant (19 vs 17), duration of noninvasive support (147 ± 181 hours vs 127 ± 137 hours), BPD incidence and death. However, duration of MV was significantly longer in NCPAP group (95.6 ± 45.8 hours vs 28.25 ± 34.1 hour), P = .01.

CONCLUSION

In infants with respiratory distress after birth, no differences in treatment failures were observed between NIV-NAVA and NCPAP. These results require further evaluation in a larger study.

Neurally adjusted ventilator assist (NAVA) reduces asynchrony during non-invasive ventilation for severe bronchiolitis

BACKGROUND

To determine the prevalence of main inspiratory asynchrony events during non-invasive intermittent positive-pressure ventilation (NIV) for severe bronchiolitis. Ventilator response time and asynchrony were compared in neurally adjusted ventilator assist (NAVA) and in pressure assist/control (PAC) modes.

METHODS

This prospective physiological study was performed in a university hospital's paediatric intensive care unit and included 11 children (aged 35.2 ± 23 days) with respiratory syncytial virus bronchiolitis with failure of nCPAP. Patients received NIV for 2 hr in PAC mode followed by 2 hr in NAVA mode. Electrical activity of the diaphragm and pressure curves were recorded for 10 min. Trigger delay, main asynchronies (auto-triggering, double triggering, or non-triggered breaths) were analyzed, and the asynchrony index was calculated for each period.

RESULTS

The asynchrony index was lower during NAVA than during PAC (3 ± 3% vs. 38 ± 21%, P < 0.0001), and the trigger delay was shorter (43.9 ± 7.2 vs. 116.0 ± 38.9 ms, P < 0.0001). Ineffective efforts were significantly less frequent in NAVA mode (0.54 ± 1.5 vs. 21.8 ± 16.5 events/min, P = 0.01). Patient respiratory rates were similar, but the ventilator rate was higher in NAVA than in PAC mode (59.5 ± 17.9 vs. 49.8 ± 8.5/min, P = 0.03). The TcPCO2 baselines values (64 ± 12 mmHg vs. 62 ± 9 mmHg during NAVA, P = 0.30) were the same and their evolution over the 2 hr study period (-6 ± 10 mmHg vs. -12 ± 17 mmHg during NAVA, P = 0.36) did not differ.

CONCLUSION

Patient-ventilator inspiratory asynchronies and trigger delay were dramatically lower in NAVA mode than in PAC mode during NIV in infants with severe bronchiolitis.

Neurally adjusted ventilatory assist for infants under prolonged ventilation

BACKGROUND

Severe bronchopulmonary dysplasia often leads to prolonged mechanical ventilation lasting several months. Cyanotic episodes frequently occur in these patients, necessitating long-term sedation and/or intermittent muscle paralysis. Neurally adjusted ventilatory assist (NAVA) might provide precisely the amount of support that these patients need without sedation.

METHODS

We reviewed the medical records of preterm infants who underwent tracheostomy and required mechanical ventilation for >6 months during a period of 6 years. We compared two groups of patients: those supported with NAVA for ≥2 months versus those supported by pneumatically triggered assist methods. We also evaluated any change after NAVA use in the NAVA group.

RESULTS

Among 14 prematurely born patients who received prolonged ventilation, nine were supported with NAVA and five were supported using other ventilator modes. Duration of continuous sedation was significantly shorter and the bolus use of sedatives was also significantly lower in the NAVA group than in the pneumatically triggered assist group. In addition, the NAVA group received a lower dose of dexamethasone than the pneumatically triggered assist group. Compared with before NAVA, the frequency of cyanotic episodes and of the bolus sedatives was significantly decreased after implementation of NAVA.

CONCLUSIONS

For infants on prolonged mechanical ventilation, NAVA could reduce cyanotic episodes and the need for sedatives and dexamethasone. NAVA may be superior to pneumatically triggered modes in terms of the minimization of patient-ventilator dyssynchrony while delivering appropriate respiratory support in premature infants with tracheostomy.

Neurally-Adjusted Ventilatory Assist for Noninvasive Ventilation via a Helmet in Subjects With COPD Exacerbation: A Physiologic Study

BACKGROUND

In patients with COPD exacerbation, noninvasive ventilation (NIV) is strongly recommended. NIV is generally delivered by using patient triggered and flow-cycled pressure support through a face mask. A specific method to generate neurally-controlled pressure support has been shown to improve comfort and patient-ventilator interaction. In addition, the helmet interface was better tolerated by patients compared with a face mask. Herein, we compared neurally-controlled pressure support through a helmet with pressure support through a face mask with respect to subject comfort, breathing pattern, gas exchange, pressurization and triggering performance, and patient-ventilator synchrony.

METHODS

Two 30-min trials of NIV were randomly delivered to 10 subjects with COPD exacerbation redundant: (1) pressure support through a face mask with inspiratory pressure support of ≥8 cm H₂O to obtain a tidal volume of 6-8 mL/kg of ideal body weight; and (2) NAVA through a helmet, setting the neurally-adjusted ventilatory assist level at 15 cm H₂O/μV, with an upper airway pressure limit to obtain the same overall airway pressure applied during pressure support through a face mask. We assessed subject comfort, breathing frequency, respiratory drive, arterial blood gases, pressure-time product (PTP) of the first 300 ms and 500ms after initiation of subject effort, inspiratory trigger delay, and rate of asynchrony determined as the asynchrony index.

RESULTS

Median and interquartile range NAVA through a helmet improved comfort (7.0 [6.0-8.0]) compared with pressure support through a face mask (5.0 [4.7-5.2], P = .005). The breathing pattern was not different between the methods. Respiratory drive was slightly, although not significantly, reduced (P = .19) during NAVA through a helmet in comparison with pressure support through a face mask. Gas exchange was also not different between the trials. The PTP of the first 300 ms (P = .92) and PTP of the first 500 ms (P = .08) were not statistically different between trials, whereas triggering performance, patient-ventilator interaction, and synchrony were all improved by NAVA through a helmet compared with pressure support through a face mask.

CONCLUSIONS

In the subjects with COPD with exacerbation, NAVA through a helmet improved comfort, triggering performance, and patient-ventilator synchrony compared with pressure support through a face mask.

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.

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.

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.

Neurally adjusted ventilatory assist and pressure support ventilation in small species and the impact of instrumental dead space

BACKGROUND

Neurally adjusted ventilatory assist (NAVA) is a pneumatically-independent mode of mechanical ventilation controlled by diaphragm electrical activity (EAdi), and has not yet been implemented in very small species.

OBJECTIVES

The aims of the study were to evaluate the feasibility of applying NAVA in very small species and to compare this to pressure support ventilation (PSV) in terms of ventilatory efficiency and breathing pattern, and evaluate the impact of instrumental dead space on breathing pattern during both modes.

METHODS

Nine healthy rats (mean weight 385 +/- 4 g) were studied while breathing on PSV or NAVA, at baseline or with added dead space.

RESULTS

A clear difference in breathing pattern between NAVA and PSV was observed during both baseline and dead space, where PSV - despite similar EAdi and tidal volume as during NAVA - caused shortened inspiratory time (p < 0.05) and increased the respiratory rate (p < 0.05). A higher minute ventilation (p < 0.05) in order to reach the same arterial CO(2) was observed. Ineffective inspiratory efforts occurred only during PSV and decreased with the dead space.

CONCLUSION

This study demonstrates, in a small group of animals, that NAVA can deliver assist in very small species with a higher efficiency than PSV in terms of eliminating CO(2) for a given minute ventilation.

Electrical impedance tomography reveals pathophysiology of neonatal pneumothorax during NAVA

Pneumothorax is a potentially life-threatening complication of neonatal respiratory distress syndrome (RDS). We describe a case of a tension pneumothorax that occurred during neurally adjusted ventilatory assist (NAVA) in a preterm infant suffering from RDS. The infant was included in a multicenter study examining the role of electrical impedance tomography (EIT) in intensive care and therefore continuously monitored with this imaging method. The attending physicians were blinded for EIT findings but offline analysis revealed the potential of EIT to clarify the underlying cause of this complication, which in this case was heterogeneous lung disease resulting in uneven ventilation distribution. Instantaneous increase in end-expiratory lung impedance on the affected side was observed at time of the air leak. Real-time bedside availability of EIT data could have modified the treatment decisions made.

Newer nonconventional modes of mechanical ventilation

The conventional modes of ventilation suffer many limitations. Although they are popularly used and are well-understood, often they fail to match the patient-based requirements. Over the years, many small modifications in ventilators have been incorporated to improve patient outcome. The ventilators of newer generation respond to patient's demands by additional feedback systems. In this review, we discuss the popular newer modes of ventilation that have been accepted in to clinical practice. Various intensive care units over the world have found these modes to improve patient ventilator synchrony, decrease ventilator days and improve patient safety. The various modes discusses in this review are: Dual control modes (volume assured pressure support, volume support), Adaptive support ventilation, proportional assist ventilation, mandatory minute ventilation, Bi-level airway pressure release ventilation, (BiPAP), neurally adjusted ventilatory assist and NeoGanesh. Their working principles with their advantages and clinical limitations are discussed in brief.

Neurally-Adjusted Ventilatory Assist Versus Noninvasive Pressure Support Ventilation in COPD Exacerbation: The NAVA-NICE Trial

BACKGROUND

This study was conducted to compare the effectiveness of noninvasive ventilation (NIV) with pressure support (NIV-PSV) to noninvasive neurally-adjusted ventilatory assist (NIV-NAVA) during COPD exacerbation.

METHODS

In this study, 40 subjects with COPD and acute hypercapnic respiratory failure were randomized to receive either NIV-NAVA (n = 20) or NIV-PSV (n = 20) via a critical care ventilator. Subjects' vital parameters, arterial blood gas values, patient-ventilator asynchrony events, and asynchrony index were noted at specific time intervals in both groups. The duration of NIV, rate of NIV failure, and length hospital stay were also recorded for these 2 modes of NIV.

RESULTS

NIV-NAVA significantly reduced the total number (median [interquartile range]) of asynchrony events compared to NIV-PSV: 22 (15-32.5) versus 65 (50.75-104.25), respectively, P = .002. Severe asynchrony defined as asynchrony index > 10% was also significantly lower in NIV-NAVA than in NIV-PSV (P < .001). There was no significant difference between the 2 groups regarding improvement in gas exchange and vital parameters. Rate of failure of NIV (P = .73), duration of the requirement of ventilatory support (P = .40), and hospital length of stay (P = .46) were also comparable between the 2 modes of ventilation.

CONCLUSIONS

Compared to NIV-PSV, NIV-NAVA was associated with better patient-ventilator synchrony and a reduction in the number of asynchrony events in subjects with an exacerbation of COPD, with similar effects on improvement in gas exchange, duration of NIV, hospital lenght of stay, and rate of NIV failure. (Clinicaltrials.gov registration NCT02912689.).

Pressure support ventilation, sigh adjunct to pressure support ventilation, and neurally adjusted ventilatory assist in infants after cardiac surgery: A physiologic crossover randomized study

OBJECTIVES

We sought to compare gas exchange, respiratory mechanics, and asynchronies during pressure support ventilation (PSV), sigh adjunct to PSV (PSV SIGH), and neurally adjusted ventilatory assist (NAVA) in hypoxemic infants after cardiac surgery.

DESIGN

Prospective, single-center, crossover, randomized physiologic study.

SETTING

Tertiary-care pediatric intensive care unit.

PATIENTS

Fourteen hypoxemic infants (median age 11.5 days [8.7-74]).

INTERVENTIONS

The protocol begins with a 1 hour step of PSV, followed by two consecutive steps in PSV SIGH and NAVA in random order, with a washout period of 30 minutes (PSV) between them.

MAIN RESULTS

Three infants presented an irregular Eadi signal because of diaphragmatic paralysis and were excluded from analysis. For the remaining 11 infants, PaO₂ /FiO ₂ and oxygenation index improved in PSV SIGH compared with PSV (P < 0.05) but not in NAVA compared with PSV. PSV SIGH showed increased tidal volumes and lower respiratory rate than PSV (P < 0.05), as well as a significant improvement in compliance with respiratory system indexed to body weight when compared with both PSV and NAVA (P < 0.01). No changes in mean airway pressure was registered among steps. Inspiratory time resulted prolonged for both PSV SIGH and NAVA than PSV (P < 0.05). NAVA showed the higher coefficient of variability in respiratory parameters and a significative decrease in asynchrony index when compared with both PSV and PSV SIGH (P < 0.01).

CONCLUSIONS

The adjunct of one SIGH per minute to PSV improved oxygenation and lung mechanics while NAVA provided the best patient-ventilator synchrony in infants after cardiac surgery.

Neurally Adjusted Ventilatory Assist Is Associated with Greater Initial Extubation Success in Postoperative Congenital Heart Disease Patients when Compared to Conventional Mechanical Ventilation

Extubation failure is associated with considerable morbidity and mortality in postoperative patients with congenital heart disease (CHD). The study purpose was to investigate initial extubation success utilizing neurally adjusted ventilatory assist (NAVA) compared with pressure-regulated volume controlled, synchronized intermittent mandatory ventilation with pressure support (SIMV-PRVC + PS) for ventilatory weaning in patients who required prolonged mechanical ventilation (MV). Also, total days on MV, inotropes, sedation, analgesia, and pediatric intensive care unit (PICU) length of stay (LOS) between both groups were compared. This was a non-randomized pilot study utilizing historical controls (SIMV-PRVC + PS; n  = 40) compared with a prospective study population (NAVA; n  = 35) in a Level I PICU and was implemented to help future trial designs. All patients ( n  = 75) required prolonged MV ≥96 hours due to their complex postoperative course. Ventilator weaning initiation and management was standardized between both groups. Ninety-seven percent of the NAVA group was successfully extubated on the initial attempt, while 80% were in the SIMV-PRVC + PS group ( p  = 0.0317). Patients placed on NAVA were eight times more likely to have successful initial extubation (odds ratio [OR]: 8.50, 95% confidence interval [CI]: 1.01, 71.82). The NAVA group demonstrated a shorter median duration on MV (9.0 vs. 11.0 days, p  = 0.032), PICU LOS (9.0 vs. 13.5 days, p  < 0.0001), and shorter median duration of days on dopamine (8.0 vs. 11.0 days, p  = 0.0022), milrinone (9.0 vs. 12.0 days, p  = 0.0002), midazolam (8.0 vs. 12.0 days, p  < 0.0001), and fentanyl (9.0 vs. 12.5 days, p  < 0.0001) compared with the SIMV-PRVC + PS group. NAVA compared with SIMV-PRVC + PS was associated with a greater initial extubation success rate. NAVA should be considered as a mechanical ventilator weaning strategy in postoperative congenital heart disease (CHD) patients and warrants further investigation.

Application of Selective Bronchial Intubation versus Neurally Adjusted Ventilatory Assist in the Management of Unilateral Pulmonary Interstitial Emphysema: An Illustrative Case and the Literature Review

In the treatment of left-sided pulmonary interstitial emphysema (PIE) in a 23-week neonate, we used two ventilatory strategies: selective bronchial intubation from day 10 to 15 and neurally adjusted ventilatory assist (NAVA) from day 18 to 26. We compared the effects and adverse effects of these two strategies. On selective bronchial intubation, desaturation was frequent. Fentanyl infusion was required. There was an episode of carbon dioxide retention coupled with hypotension. On NAVA, the neonate was clinically stable without the requirement of sedation. On selective bronchial intubation, ventilator setting in terms of mean airway pressure and oxygen requirement was higher, which came down on the first day of NAVA. Radiologically unilateral PIE did not resolve and became localized in the left middle zone of lung field on selective bronchial intubation. Also, the lobar collapse of ipsilateral, as well as contralateral lungs occurred. On NAVA, unilateral PIE resolved. NAVA might be a good option for the management of unilateral PIE.

Comparing Noninvasive Ventilation Delivered Using Neurally-Adjusted Ventilatory Assist or Pressure Support in Acute Respiratory Failure

BACKGROUND

The use of neurally-adjusted ventilatory assist (NAVA) during noninvasive ventilation (NIV) results in better patient-ventilator interaction. Whether this improves clinical outcomes lacks dedicated study.

METHODS

In this randomized controlled trial, we compared NAVA with PSV for delivering NIV in consecutive subjects with de novo acute respiratory failure. The primary outcomes were NIV failure rates and 28-d mortality. The secondary outcomes were asynchrony index, NIV-related complications, and others.

RESULTS

We enrolled 100 subjects (50 subjects each for NAVA and PSV, 60% male) with a mean ± SD age of 56.7 ± 12 y. There was no difference in NIV failure rates (30% vs 32%, P = .83) and 28-d mortality rates (18% vs 34%, P = .07) between the NAVA and PSV arms, respectively. The median asynchrony index was significantly lower with NAVA (6.7 vs 44.8, P < .001). The use of NAVA significantly reduced NIV-related complications (32% vs 58%, P = .01). In a post hoc analysis, the use of NAVA significantly reduced the 28-d mortality in subjects with COPD exacerbation.

CONCLUSIONS

The use of NAVA during NIV did not improve NIV failure rate or 28-d mortality in subjects with acute respiratory failure. However, patient-ventilator asynchrony and NIV-related complications were reduced with NAVA.

TRIAL REGISTRY

www.clinicaltrials.gov (NCT03271671).

Case report: Non-invasive neurally adjusted ventilatory assist in a newborn with unilateral diaphragmatic paralysis

Diaphragmatic paralysis is a rare cause of respiratory distress in the newborn. In this paper, a patient with unilateral phrenic nerve injury after traumatic delivery is presented. The child inadequately responded to standard respiratory supportive measures. Non-invasive neurally adjusted ventilatory assist (NIV-NAVA®), providing an optimally synchronized respiratory support proportional to the effort of the patient, resulted in prompt clinical and biological improvement of the patient's respiratory condition. NAVA is a relatively new mode of ventilation in neonatal care. In this case of unilateral diaphragmatic paralysis, it provided an alternative strategy of non-invasive respiratory support avoiding prolonged mechanical ventilation. Pediatr Pulmonol. 2016;51:E37-E39. © 2016 Wiley Periodicals, Inc.

Work of Breathing in Premature Neonates: Noninvasive Neurally-Adjusted Ventilatory Assist versus Noninvasive Ventilation

BACKGROUND

We tested whether work of breathing in premature newborns estimated by phase angle (θ) by using respiratory inductance plethysmography is decreased during neurally-adjusted ventilatory assist (NAVA) noninvasive ventilation (NIV) versus NIV alone.

METHODS

NAVA NIV and NIV were applied in random order while using respiratory inductance plethysmography to measure the phase angle.

RESULTS

Patient-ventilator asynchrony was decreased during NAVA NIV; however, the phase angle was not different between the modes. A large number of repeated assists with switches to backup were found when using NAVA NIV. Results of the analysis indicated these were due to the apnea alarm limit set during NAVA NIV.

CONCLUSIONS

The improvement in patient-ventilator synchrony supports the hypothesis that work of breathing may be decreased with NAVA NIV; however, we were unable to demonstrate this with our study design. Short apnea time settings with NAVA NIV led to a large number of switches to backup and repeated assists during the same neural effort. (ClinicalTrials.gov registration NCT02788110.).

Comparison of Work of Breathing Between Noninvasive Ventilation and Neurally Adjusted Ventilatory Assist in a Healthy and a Lung-Injured Piglet Model

BACKGROUND

Noninvasive ventilation (NIV) is commonly used in neonates. A mode of NIV called neurally adjusted ventilatory assist (NAVA) offers patient-ventilator interactions by using electrical activity of the diaphragm to control mechanical breaths. We hypothesized that the work of breathing (WOB) would decrease with NIV-NAVA. Secondary objectives evaluated the impact of NIV-NAVA on arterial blood gases and respiratory parameters.

METHODS

We compared WOB between synchronized breaths in NIV-NAVA and NIV in piglets with healthy lungs and then with surfactant-depleted lungs. Neonatal pigs (median, 2.0 [range, 1.8-2.4] kg) with healthy and then surfactant depleted lungs were sedated and ventilated with NIV-NAVA and NIV in random order. Airway flow and pressure waveforms were acquired. Waveforms were analyzed for the pressure-time product that reflected WOB. The primary outcome between modes was assessed with repeated measurement analysis of variance.

RESULTS

The pressure-time product was significantly decreased for NIV-NAVA in both healthy and injured lungs (P < .001). P_aO2 , P_aCO2 , inspiratory tidal volume, and peak inspiratory flow were not different in either model.

CONCLUSIONS

Synchronized breaths during NIV-NAVA resulted in decreased WOB compared with synchronized breaths during NIV.

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.

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.

Neurally-Adjusted Ventilatory Assist (NAVA) versus Pneumatically Synchronized Ventilation Modes in Children Admitted to PICU

Traditionally, invasively ventilated children in the paediatric intensive care unit (PICU) are weaned using pneumatically-triggered ventilation modes with a fixed level of assist. The best weaning mode is currently not known. Neurally adjusted ventilatory assist (NAVA), a newer weaning mode, uses the electrical activity of the diaphragm (Edi) to synchronise ventilator support proportionally to the patient’s respiratory drive. We aimed to perform a systematic literature review to assess the effect of NAVA on clinical outcomes in invasively ventilated children with non-neonatal lung disease. Three studies (n = 285) were included for analysis. One randomised controlled trial (RCT) of all comers showed a significant reduction in PICU length of stay and sedative use. A cohort study of acute respiratory distress syndrome (ARDS) patients (n = 30) showed a significantly shorter duration of ventilation and improved sedation with the use of NAVA. A cohort study of children recovering from cardiac surgery (n = 75) showed significantly higher extubation success, shorter duration of ventilation and PICU length of stay, and a reduction in sedative use. Our systematic review presents weak evidence that NAVA may shorten the duration of ventilation and PICU length of stay, and reduce the requirement of sedatives. However, further RCTs are required to more fully assess the effect of NAVA on clinical outcomes and treatment costs in ventilated children.

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.