Neurally Adjusted Ventilatory Assist (NAVA): Reference Values for the Electrical Activity of the Diaphragm (Edi ) in Neonates

Background During conventional Neurally Adjusted Ventilatory Assist (NAVA), the electrical activity of the diaphragm (EAdi) is used for triggering and cycling-off inspiratory assist, with a fixed PEEP (so called “Triggered Neurally Adjusted Ventilatory Assist” or “tNAVA”). However, significant post-inspiratory activity of the diaphragm can occur, believed to play a role in maintaining end-expiratory lung volume. Adjusting pressure continuously, in proportion to both inspiratory and expiratory EAdi (Continuous NAVA, or cNAVA), would not only offer inspiratory assist for tidal breathing, but also may aid in delivering a “neurally adjusted PEEP”, and more specific breath-by-breath unloading. Methods Nine adult New Zealand white rabbits were ventilated during independent conditions of: resistive loading (RES1 or RES2), CO2 load (CO2) and acute lung injury (ALI), either via tracheotomy (INV) or non-invasively (NIV). There were a total of six conditions, applied in a non-randomized fashion: INV-RES1, INV-CO2, NIV-CO2, NIV-RES2, NIV-ALI, INV-ALI. For each condition, tNAVA was applied first (3 min), followed by 3 min of cNAVA. This comparison was repeated 3 times (repeated cross-over design). The NAVA level was always the same for both modes, but was newly titrated for each condition. PEEP was manually set to zero during tNAVA. During cNAVA, the assist during expiration was proportional to the EAdi. During all runs and conditions, ventilator-delivered pressure (Pvent), esophageal pressure (Pes), and diaphragm electrical activity (EAdi) were measured continuously. The tracings were analyzed breath-by-breath to obtain peak inspiratory and mean expiratory values. Results For the same peak Pvent, the distribution of inspiratory and expiratory pressure differed between tNAVA and cNAVA. For each condition, the mean expiratory Pvent was always higher (for all conditions 4.0 ± 1.1 vs. 1.1 ± 0.5 cmH2O, P < 0.01) in cNAVA than in tNAVA. Relative to tNAVA, mean inspiratory EAdi was reduced on average (for all conditions) by 19 % (range 14 %–25 %), p < 0.05. Mean expiratory EAdi was also lower during cNAVA (during INV-RES1, INV-CO2, INV-ALI, NIV-CO2 and NIV-ALI respectively, P < 0.05). The inspiratory Pes was reduced during cNAVA all 6 conditions (p < 0.05). Unlike tNAVA, during cNAVA the expiratory pressure was comparable with that predicted mathematically (mean difference of 0.2 ± 0.8 cmH2O). Conclusion Continuous NAVA was able to apply neurally adjusted PEEP, which led to a reduction in inspiratory effort compared to triggered NAVA.

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Reference values for diaphragm electrical activity (Edi) in newborn infants

10.22541/au.162514165.52117415/v1 ◽

2021 ◽

Author(s):

Varappriyangga Gurumahan ◽

Sriganesh Thavalingam ◽

Tim Schindler ◽

John Smyth ◽

Kei Lui ◽

...

Keyword(s):

Electrical Activity ◽

Reference Values ◽

Newborn Infants ◽

Feeding Tube ◽

Respiratory Support ◽

Neurally Adjusted Ventilatory Assist ◽

Term Infants ◽

Term Neonates ◽

Diaphragm Electrical Activity ◽

The Mean

Background: Neurally adjusted ventilatory assist (NAVA) is an emerging mode of respiratory support that uses the electrical activity of the diaphragm (Edi) to provide synchronised inspiratory pressure support, proportional to an infant’s changing inspiratory effort. Data on Edi reference values for neonates are limited. The objective of this study was to establish reference Edi values for preterm and term neonates. Methods: This was a prospective observational study of newborn infants breathing spontaneously in room air. The Edi signal was monitored by a specialised intragastric feeding tube with embedded electrodes positioned at the level of the diaphragm. Edi minimums and peaks were recorded continuously for four hours. Results: 24 newborn infants (16 preterm [<37 weeks’ gestation]; 8 term) were studied. All infants were breathing comfortably in room air at the time of study. Edi data were successfully captured in all infants. The mean (±SD) Edi minimum was 3.02 (±0.94) µV and the mean Edi peak was 10.13 (±3.50) µV. In preterm infants the mean (±SD) Edi minimum was 3.05 (±0.91) µV and the mean Edi peak was 9.36 (±2.13) µV. In term infants the mean (±SD) Edi minimum was 2.97 (±1.05) µV and the mean Edi peak was 11.66 (±5.14) µV. Conclusion: Reference Edi values were established for both preterm and term neonates. These values can be used as a guide when using diaphragm-triggered modes on respiratory support in newborn infants.

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Ventilator auto-triggering by cardiac electrical activity during noninvasive ventilation with neurally adjusted ventilatory assist

Clinical Case Reports ◽

10.1002/ccr3.1590 ◽

2018 ◽

Vol 6 (7) ◽

pp. 1379-1380

Author(s):

Yu Inata ◽

Muneyuki Takeuchi

Keyword(s):

Electrical Activity ◽

Noninvasive Ventilation ◽

Neurally Adjusted Ventilatory Assist ◽

Cardiac Electrical Activity ◽

Ventilatory Assist

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Neurally Adjusted Ventilatory Assist in Critically Ill Postoperative Patients: A Crossover Randomized Study

Anesthesiology ◽

10.1097/aln.0b013e3181ee2ef1 ◽

2010 ◽

Vol 113 (4) ◽

pp. 925-935 ◽

Cited By ~ 57

Author(s):

Yannael Coisel ◽

Gerald Chanques ◽

Boris Jung ◽

Jean-Michel Constantin ◽

Xavier Capdevila ◽

...

Keyword(s):

Mechanical Ventilation ◽

Gas Exchange ◽

Electrical Activity ◽

Tidal Volume ◽

Critically Ill ◽

Neurally Adjusted Ventilatory Assist ◽

Exchange Effects ◽

Ventilatory Parameters ◽

Ventilatory Assist ◽

Ventilation Modes

Background Neurally adjusted ventilatory assist (NAVA) is a new mode of mechanical ventilation that delivers ventilatory assist in proportion to the electrical activity of the diaphragm. This study aimed to compare the ventilatory and gas exchange effects between NAVA and pressure support ventilation (PSV) during the weaning phase of critically ill patients who required mechanical ventilation subsequent to surgery. Methods Fifteen patients, the majority of whom underwent abdominal surgery, were enrolled. They were ventilated with PSV and NAVA for 24 h each in a randomized crossover order. The ventilatory parameters and gas exchange effects produced by the two ventilation modes were compared. The variability of the ventilatory parameters was also evaluated by the coefficient of variation (SD to mean ratio). Results Two patients failed to shift to NAVA because of postoperative bilateral diaphragmatic paralysis, and one patient interrupted the study because of worsening of his sickness. In the other 12 cases, the 48 h of the study protocol were completed, using both ventilation modes, with no signs of intolerance or complications. The Pao2/Fio2 (mean ± SD) ratio in NAVA was significantly higher than with PSV (264 ± 71 vs. 230 ± 75 mmHg, P < 0.05). Paco2 did not differ significantly between the two modes. The tidal volume (median [interquartile range]) with NAVA was significantly lower than with PSV (7.0 [6.4-8.6] vs. 6.5 [6.3-7.4] ml/kg predicted body weight, P < 0.05).Variability of insufflation airway pressure, tidal volume, and minute ventilation were significantly higher with NAVA than with PSV. Electrical activity of the diaphragm variability was significantly lower with NAVA than with PSV. Conclusions Compared with PSV, respiratory parameter variability was greater with NAVA, probably leading in part to the significant improvement in patient oxygenation.

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