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Background Prolonged controlled mechanical ventilation depresses diaphragmatic efficiency. Assisted modes of ventilation should improve it. We assessed the impact of pressure support ventilation versus neurally adjusted ventilator assist on diaphragmatic efficiency. Method Patients previously ventilated with controlled mechanical ventilation for 72 hours or more were randomized to be ventilated for 48 hours with pressure support ventilation (n =12) or neurally adjusted ventilatory assist (n = 13). Neuro-ventilatory efficiency (tidal volume/diaphragmatic electrical activity) and neuro-mechanical efficiency (pressure generated against the occluded airways/diaphragmatic electrical activity) were measured during three spontaneous breathing trials (0, 24 and 48 hours). Breathing pattern, diaphragmatic electrical activity and pressure time product of the diaphragm were assessed every 4 hours. Results In patients randomized to neurally adjusted ventilator assist, neuro-ventilatory efficiency increased from 27 ± 19 ml/μV at baseline to 62 ± 30 ml/μV at 48 hours (p <0.0001) and neuro-mechanical efficiency increased from 1 ± 0.6 to 2.6 ± 1.1 cmH 2 O/μV (p = 0.033). In patients randomized to pressure support ventilation, these did not change. Electrical activity of the diaphragm, neural inspiratory time, pressure time product of the diaphragm and variability of the breathing pattern were significantly higher in patients ventilated with neurally adjusted ventilatory assist. The asynchrony index was 9.48 [6.38– 21.73] in patients ventilated with pressure support ventilation and 5.39 [3.78– 8.36] in patients ventilated with neurally adjusted ventilatory assist (p = 0.04). Conclusion After prolonged controlled mechanical ventilation, neurally adjusted ventilator assist improves diaphragm efficiency whereas pressure support ventilation does not. Trial registration ClinicalTrials.gov study registration: NCT0247317 , 06/11/2015.

In this randomized trial, proportional-assist ventilation with load-adjustable gain factors did not differ significantly from pressure-support ventilation with respect to the time to liberation from mechanical ventilation.

Purpose Neurally adjusted ventilatory assist (NAVA) is a ventilatory mode that tailors the level of assistance delivered by the ventilator to the electromyographic activity of the diaphragm. The objective of this study was to compare NAVA and pressure support ventilation (PSV) in the early phase of weaning from mechanical ventilation. Methods A multicentre randomized controlled trial of 128 intubated adults recovering from acute respiratory failure was conducted in 11 intensive care units. Patients were randomly assigned to NAVA or PSV. The primary outcome was the probability of remaining in a partial ventilatory mode (either NAVA or PSV) throughout the first 48 h without any return to assist-control ventilation. Secondary outcomes included asynchrony index, ventilator-free days and mortality. Results In the NAVA and PSV groups respectively, the proportion of patients remaining in partial ventilatory mode throughout the first 48 h was 67.2 vs. 63.3 % ( P  = 0.66), the asynchrony index was 14.7 vs. 26.7 % ( P  < 0.001), the ventilator-free days at day 7 were 1.0 day [1.0–4.0] vs. 0.0 days [0.0–1.0] ( P  < 0.01), the ventilator-free days at day 28 were 21 days [4–25] vs. 17 days [0–23] ( P  = 0.12), the day-28 mortality rate was 15.0 vs. 22.7 % ( P  = 0.21) and the rate of use of post-extubation noninvasive mechanical ventilation was 43.5 vs. 66.6 % ( P  < 0.01). Conclusions NAVA is safe and feasible over a prolonged period of time but does not increase the probability of remaining in a partial ventilatory mode. However, NAVA decreases patient–ventilator asynchrony and is associated with less frequent application of post-extubation noninvasive mechanical ventilation. Trial Registration. clinicaltrials.gov Identifier: NCT02018666.

Background Noninvasive neurally adjusted ventilator assist (NIV-NAVA) was introduced to our clinical practice via a pilot and a randomized observational study to assess its safety, feasibility, and short-term physiological effects. Methods The pilot protocol applied NIV-NAVA to 11 infants on nasal CPAP, high-flow nasal cannula, or nasal intermittent mandatory ventilation (NIMV), in multiple 2- to 4-h periods of NIV-NAVA for comparison. This provided the necessary data to design a randomized, controlled observational crossover study in eight additional infants to compare the physiological effects of NIV-NAVA with NIMV during 2-h steady-state conditions. We recorded the peak inspiratory pressure (PIP), FiO 2 , Edi, oxygen saturations (histogram analysis), transcutaneous PCO 2 , and movement with an Acoustic Respiratory Movement Sensor. Results The NAVA catheter was used for 81 patient days without complications. NIV-NAVA produced significant reductions (as a percentage of measurements on NIMV) in the following: PIP, 13%; FiO 2 , 13%; frequency of desaturations, 42%; length of desaturations, 32%; and phasic Edi, 19%. Infant movement and caretaker movement were reduced by 42% and 27%, respectively. Neural inspiratory time was increased by 39 ms on NIV-NAVA, possibly due to Head’s paradoxical reflex. Conclusion NIV-NAVA was a safe, alternative mode of noninvasive support that produced beneficial short-term physiological effects, especially compared with NIMV.

PurposeThe aim of this study was to compare the effect of a pressure-controlled strategy allowing non-synchronised unassisted spontaneous ventilation (PC-SV) to a conventional volume assist-control strategy (ACV) on the outcome of patients with acute respiratory distress syndrome (ARDS).MethodsOpen-label randomised clinical trial in 22 intensive care units (ICU) in France. Seven hundred adults with moderate or severe ARDS (PaO2/FiO2 < 200 mmHg) were enrolled from February 2013 to October 2018. Patients were randomly assigned to PC-SV (n = 348) or ACV (n = 352) with similar objectives of tidal volume (6 mL/kg predicted body weight) and positive end-expiratory pressure (PEEP). Paralysis was stopped after 24 h and sedation adapted to favour patients’ spontaneous ventilation. The primary endpoint was in-hospital death from any cause at day 60.ResultsHospital mortality [34.6% vs 33.5%, p = 0.77, risk ratio (RR) = 1.03 (95% confidence interval [CI] 0.84–1.27)], 28-day mortality, as well as the number of ventilator-free days and organ failure-free days at day 28 did not differ between PC-SV and ACV groups. Patients in the PC-SV group received significantly less sedation and neuro-muscular blocking agents than in the ACV group. A lower proportion of patients required adjunctive therapy of hypoxemia (including prone positioning) in the PC-SV group than in the ACV group [33.1% vs 41.3%, p = 0.03, RR = 0.80 (95% CI 0.66–0.98)]. The incidences of pneumothorax and refractory hypoxemia did not differ between the groups.ConclusionsA strategy based on PC-SV mode that favours spontaneous ventilation reduced the need for sedation and adjunctive therapies of hypoxemia but did not significantly reduce mortality compared to ACV with similar tidal volume and PEEP levels.

ObjectiveTo compare non-invasive ventilation neurally adjusted ventilatory assist (NIV-NAVA) and non-invasive pressure support (NIV-PS) in preterm infants on patient–ventilator synchrony.DesignA randomised phase II crossover trial.SettingNeonatal intensive care units of two tertiary university hospitals in Korea.PatientsPreterm infants born <32 weeks.InterventionNIV-NAVA and NIV-PS were applied in random order after ventilator weaning. Data were recorded for sequential 5 min periods after 10 min applications of each mode.Main outcome measuresThe electrical activity of the diaphragm (Edi), ventilator flow and pressure curves were compared to examine the trigger delay (primary outcome) and other parameters of patient–ventilator interaction (secondary outcomes) for each period.ResultsFifteen infants completed the protocol. Trigger delay (35.2±8.3 vs 294.6±101.9 ms, p<0.001), ventilator inspiratory time (423.3±87.1 vs 534.0±165.5 ms, p=0.009) and inspiratory time in excess (32.3±8.3% vs 294.6±101.9%, p=0.001) were lower during NIV-NAVA compared with NIV-PS. Maximum Edi (12.6±6.3 vs 16.6±8.7 μV, p=0.003), swing Edi (8.8±4.8 vs 12.2±8.7 μV, p=0.012) and peak inspiratory pressure (12.3±1.5 vs 14.7±2.7 cm H2O, p=0.003) were also lower during NIV-NAVA. The main asynchrony events during NIV-PS were ineffective efforts and autotriggering. All types of asynchronies except double triggering were reduced with NIV-NAVA. Asynchrony index was significantly lower during NIV-NAVA compared with NIV-PS (p<0.001). No significant differences in leakage, expiratory tidal volume or minute ventilation were observed, but the respiratory rate was lower during NIV-PS than during NIV-NAVA.ConclusionsNAVA improved patient–ventilator synchrony and diaphragmatic unloading in preterm infants during non-invasive nasal ventilation even in the presence of large air leaks.Trial registration numberRegistered with http://www.clinicaltrials.gov (NCT01877720).

In pediatric liver recipients perioperative factors may affect respiratory and cardiac function, and prolong mechanical ventilation during post-operative period. The use of NAVA can improve the interaction between the patient and the ventilator from both a respiratory and cardiac perspective. The objective of this study is to evaluate the synchronization between the patient and the ventilator, as well as cardiac function, during the application of neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) in pediatric liver transplant recipients. This is a single-center, prospective, randomized, physiological cross-over controlled trial conducted between 2021 and 2022. Children (1 month-10 years old) who underwent liver transplantation were admitted to the pediatric intensive care unit. Patients were randomised to one of two crossover sequences of ventilation trials of 40 min each (PSV/NAVA/PSV or NAVA/PSV/NAVA). Cardiac function was studied by echocardiogram. Twenty-four patients were enrolled and 21 completed the study. Primary outcomes were variation of asynchrony index (AI) and tricuspid annular plane systolic excursion (TAPSE) during the two ventilation modes. Secondary outcomes were patient-ventilator interaction parameters, gas exchange, left and right ventricular function, and hemodynamic parameters. NAVA compared to PSV: (1) improves patient-ventilator interaction reducing AI (coeff − 6.66 95% CI −11.5 to −1.78, p  = 0.008); (2) does not improve TAPSE (coeff 0.62 95% CI −1.49 to 2.74, p  < 0.557) No differences in terms of pulmonary gas exchange and hemodynamic parameters were detected. NAVA (when compared to PSV) improves patient-ventilator interaction in terms of asynchronies without affecting cardiac biventricular function. Trial registration : NCT 04792788, Registration date: 2021-03-11.

Impairments in cognitive function, mood, and sleep quality occur following ascent to high altitude. Low oxygen (hypoxia) and poor sleep quality are both linked to impaired cognitive performance, but their independent contributions at high altitude remain unknown. Adaptive servoventilation (ASV) improves sleep quality by stabilizing breathing and preventing central apneas without supplemental oxygen. We compared the efficacy of ASV and supplemental oxygen sleep treatments for improving daytime cognitive function and mood in high-altitude visitors (N = 18) during acclimatization to 3,800 m. Each night, subjects were randomly provided with ASV, supplemental oxygen (SpO2 > 95%), or no treatment. Each morning subjects completed a series of cognitive function tests and questionnaires to assess mood and multiple aspects of cognitive performance. We found that both ASV and supplemental oxygen (O2) improved daytime feelings of confusion (ASV: p < 0.01; O2: p < 0.05) and fatigue (ASV: p < 0.01; O2: p < 0.01) but did not improve other measures of cognitive performance at high altitude. However, performance improved on the trail making tests (TMT) A and B (p < 0.001), the balloon analog risk test (p < 0.0001), and the psychomotor vigilance test (p < 0.01) over the course of three days at altitude after controlling for effects of sleep treatments. Compared to sea level, subjects reported higher levels of confusion (p < 0.01) and performed worse on the TMT A (p < 0.05) and the emotion recognition test (p < 0.05) on nights when they received no treatment at high altitude. These results suggest that stabilizing breathing (ASV) or increasing oxygenation (supplemental oxygen) during sleep can reduce feelings of fatigue and confusion, but that daytime hypoxia may play a larger role in other cognitive impairments reported at high altitude. Furthermore, this study provides evidence that some aspects of cognition (executive control, risk inhibition, sustained attention) improve with acclimatization.

Background Invasive mechanical ventilation contributes to bronchopulmonary dysplasia (BPD), the most common complication of prematurity and the leading respiratory cause of childhood morbidity. Non-invasive ventilation (NIV) may limit invasive ventilation exposure and can be either synchronized or non-synchronized (NS). Pooled data suggest synchronized forms may be superior. Non-invasive neurally adjusted ventilatory assist (NIV-NAVA) delivers NIV synchronized to the neural signal for breathing, which is detected with a specialized catheter. The DIVA (Diaphragmatic Initiated Ventilatory Assist) trial aims to determine in infants born 24 0/7 –27 6/7  weeks’ gestation undergoing extubation whether NIV-NAVA compared to non-synchronized nasal intermittent positive pressure ventilation (NS-NIPPV) reduces the incidence of extubation failure within 5 days of extubation. Methods This is a prospective, unblinded, pragmatic, multicenter phase III randomized clinical trial. Inclusion criteria are preterm infants 24–27 6/7  weeks gestational age who were intubated within the first 7 days of life for at least 12 h and are undergoing extubation in the first 28 postnatal days. All sites will enter an initial run-in phase, where all infants are allocated to NIV-NAVA, and an independent technical committee assesses site performance. Subsequently, all enrolled infants are randomized to NIV-NAVA or NS-NIPPV at extubation. The primary outcome is extubation failure within 5 days of extubation, defined as any of the following: (1) rise in FiO 2 at least 20% from pre-extubation for > 2 h, (2) pH ≤ 7.20 or pCO 2  ≥ 70 mmHg; (3) > 1 apnea requiring positive pressure ventilation (PPV) or ≥ 6 apneas requiring stimulation within 6 h; (4) emergent intubation for cardiovascular instability or surgery. Our sample size of 478 provides 90% power to detect a 15% absolute reduction in the primary outcome. Enrolled infants will be followed for safety and secondary outcomes through 36 weeks’ postmenstrual age, discharge, death, or transfer. Discussion The DIVA trial is the first large multicenter trial designed to assess the impact of NIV-NAVA on relevant clinical outcomes for preterm infants. The DIVA trial design incorporates input from clinical NAVA experts and includes innovative features, such as a run-in phase, to ensure consistent technical performance across sites. Trial registration www.ClinicalTrials.gov , trial identifier NCT05446272 , registered July 6, 2022.

Neurally adjusted ventilatory assist (NAVA) improves patient-ventilator synchrony during invasive ventilation and leads to lower peak inspiratory pressures (PIP) and oxygen requirements. The aim of this trial was to compare NAVA with current standard ventilation in preterm infants in terms of the duration of invasive ventilation. Sixty infants born between 28 + 0 and 36 + 6 weeks of gestation and requiring invasive ventilation due to neonatal respiratory distress syndrome (RDS) were randomized to conventional ventilation or NAVA. The median durations of invasive ventilation were 34.7 h (quartiles 22.8–67.9 h) and 25.8 h (15.6–52.1 h) in the NAVA and control groups, respectively ( P  = 0.21). Lower PIPs were achieved with NAVA ( P  = 0.02), and the rapid reduction in PIP after changing the ventilation mode to NAVA made following the predetermined extubation criteria challenging. The other ventilatory and vital parameters did not differ between the groups. Frequent apneas and persistent pulmonary hypertension were conditions that limited the use of NAVA in 17 % of the patients randomized to the NAVA group. Similar cumulative doses of opiates were used in both groups ( P  = 0.71). Conclusions : NAVA was a safe and feasible ventilation mode for the majority of preterm infants suffering from RDS, but the traditional extubation criteria were not clinically applicable during NAVA. What is known: • NAVA improves patient-ventilator synchrony during invasive ventilation. • Lower airway pressures and oxygen requirements are achieved with NAVA during invasive ventilation in preterm infants by comparison with conventional ventilation. What is new: • Infants suffering from PPHN did not tolerate NAVA in the acute phase of their illness. • The traditional extubation criteria relying on inspiratory pressures and spontaneous breathing efforts were not clinically applicable during NAVA.