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

Effect of high-frequency oscillatory ventilation with intermittent sigh breaths on carbon dioxide levels in neonates

BACKGROUND

High-frequency oscillatory ventilation (HFOV) minimizes ventilator-induced lung injuries. Spontaneous sigh breathing may augment the functional residual capacity, increase lung compliance, and recruit atelectatic alveoli.

PURPOSE

To evaluate the difference in the partial pressure of carbon dioxide (PaCO2) in neonates receiving invasive HFOV as the primary mode of respiratory support before versus after sigh breaths (Sighs).

METHODS

This prospective study was conducted between January and December 2023. Intubated preterm and term neonates who underwent HFOV with an available arterial line were enrolled in this study after informed parental consent was obtained. Sighs were set at a frequency of 3 breaths/min and pressure of 5 cmH2O above the mean airway pressure for 2 hours. Arterial blood gas was collected before and after Sighs and analyzed using 2 dependent tests.

RESULTS

Thirty neonates with a mean gestational age of 33.6±4.1 weeks and median date of intervention of 1.88 days (interquartile range, 0.87-3.79 days) were enrolled. The mean PaCO2 level was significantly lower in the HFOV with Sighs group (45.2±6.6 mmHg) versus the HFOV alone group (48.8±3.1 mmHg) with a mean difference (MD) of -3.6 mmHg (95% confidence interval [CI], -6.3 to -0.9; P=0.01). Subgroup analyses indicated the ability of Sighs to reduce the PaCO2 level in neonates with respiratory distress syndrome (n=15; MD [95% CI]=-4.2 [-8.2 to -0.2] mmHg; P= 0.04).

CONCLUSION

Sighing can reduce PaCO2 levels in neonates ventilated with HFOV, particularly those with respiratory distress syndrome.

Neurally adjusted ventilatory assist (NAVA) in neonatal and pediatric critical care-A scoping review of randomized controlled trials

We Aimed to analyze for which indications neurally adjusted ventilatory assist (NAVA) has been studied in pediatric patients by conducting a scoping review. PubMed, Scopus, and Web of Science databases were searched in September 2023. We included all randomized trials (including crossover, parallel, and cluster) comparing NAVA to other invasive ventilation modalities in children aged <18 years. We had three key outcomes. What have been the patient and disease groups where NAVA has been studied? What kind of trials and what has been the risk of bias in these randomized trials? What have been the most used outcomes and main findings? The risk of bias was assessed according to the risk of bias 2.0 tool. This review has been reported as preferred in PRISMA-ScR guidelines. After screening 367 abstracts, 27 full reports were assessed and finally 13 studies were included. Six studies were conducted in neonates and seven in older pediatric patients. Ten of the studies were crossover and three were parallel randomized. Overall risk of bias was low in two studies, had some concerns in six studies, and was high in five studies. Most issues came from the randomization process and bias in the selection of reported results. Most used outcomes were changes in clinical parameters or measurements (such as ventilation peak and mean airway pressures, oxygenation index), and ventilator synchrony. Three parallel group trials focused on ventilation duration. The majority of the studies found NAVA as a possible alternative ventilation strategy. Although NAVA is a widely used strategy in neonatal and pediatric intensive care the current literature has notable limitations due to the risk of bias in the original studies and lack of parallel studies focusing on clinical or cost-effectiveness outcomes.

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.

A narrative review of advanced ventilator modes in the pediatric intensive care unit

Respiratory failure is a common reason for pediatric intensive care unit admission. The vast majority of children requiring mechanical ventilation can be supported with conventional mechanical ventilation (CMV) but certain cases with refractory hypoxemia or hypercapnia may require more advanced modes of ventilation. This paper discusses what we have learned about the use of advanced ventilator modes [e.g., high-frequency oscillatory ventilation (HFOV), high-frequency percussive ventilation (HFPV), high-frequency jet ventilation (HFJV) airway pressure release ventilation (APRV), and neurally adjusted ventilatory assist (NAVA)] from clinical, animal, and bench studies. The evidence supporting advanced ventilator modes is weak and consists of largely of single center case series, although a few RCTs have been performed. Animal and bench models illustrate the complexities of different modes and the challenges of applying these clinically. Some modes are proprietary to certain ventilators, are expensive, or may only be available at well-resourced centers. Future efforts should include large, multicenter observational, interventional, or adaptive design trials of different rescue modes (e.g., PROSpect trial), evaluate their use during ECMO, and should incorporate assessments through volumetric capnography, electric impedance tomography, and transpulmonary pressure measurements, along with precise reporting of ventilator parameters and physiologic variables.

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.

Pressure Support Ventilation (PSV) versus Neurally Adjusted Ventilatory Assist (NAVA) in difficult to wean pediatric ARDS patients: a physiologic crossover study

BACKGROUND

Neurally adjusted ventilatory assist (NAVA) is an innovative mode for assisted ventilation that improves patient-ventilator interaction in children. The aim of this study was to assess the effects of patient-ventilator interaction comparing NAVA with pressure support ventilation (PSV) in patients difficult to wean from mechanical ventilation after moderate pediatric acute respiratory distress syndrome (PARDS).

METHODS

In this physiological crossover study, 12 patients admitted in the Pediatric Intensive Care Unit (PICU) with moderate PARDS failing up to 3 spontaneous breathing trials in less than 7 days, were enrolled. Patients underwent three study conditions lasting 1 h each: PSV1, NAVA and PSV2.

RESULTS

The Asynchrony Index (AI) was significantly reduced during the NAVA trial compared to both the PSV1 and PSV2 trials (p = 0.001). During the NAVA trial, the inspiratory and expiratory trigger delays were significantly shorter compared to those obtained during PSV1 and PSV2 trials (Delay_trinspp < 0.001, Delay_trexpp = 0.013). These results explain the significantly longer Time_sync observed during the NAVA trial (p < 0.001). In terms of gas exchanges, PaO₂ value significantly improved in the NAVA trial with respect to the PSV trials (p < 0.02). The PaO₂/FiO₂ ratio showed a significant improvement during the NAVA trial compared to both the PSV1 and PSV2 trials (p = 0.004).

CONCLUSIONS

In this specific PICU population, presenting difficulty in weaning after PARDS, NAVA was associated with a reduction of the AI and a significant improvement in oxygenation compared to PSV mode.

TRIAL REGISTRATION

ClinicalTrial.gov Identifier: NCT04360590 "Retrospectively registered".