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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.

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.

Background The clinical effectiveness of neurally adjusted ventilatory assist (NAVA) has yet to be demonstrated, and preliminary studies are required. The study aim was to assess the feasibility of a randomized controlled trial (RCT) of NAVA versus pressure support ventilation (PSV) in critically ill adults at risk of prolonged mechanical ventilation (MV). Methods An open-label, parallel, feasibility RCT ( n  = 78) in four ICUs of one university-affiliated hospital. The primary outcome was mode adherence (percentage of time adherent to assigned mode), and protocol compliance (binary—≥ 65% mode adherence). Secondary exploratory outcomes included ventilator-free days (VFDs), sedation, and mortality. Results In the 72 participants who commenced weaning, median (95% CI) mode adherence was 83.1% (64.0–97.1%) and 100% (100–100%), and protocol compliance was 66.7% (50.3–80.0%) and 100% (89.0–100.0%) in the NAVA and PSV groups respectively. Secondary outcomes indicated more VFDs to D28 (median difference 3.0 days, 95% CI 0.0–11.0; p  = 0.04) and fewer in-hospital deaths (relative risk 0.5, 95% CI 0.2–0.9; p  = 0.032) for NAVA. Although overall sedation was similar, Richmond Agitation and Sedation Scale (RASS) scores were closer to zero in NAVA compared to PSV ( p  = 0.020). No significant differences were observed in duration of MV, ICU or hospital stay, or ICU, D28, and D90 mortality. Conclusions This feasibility trial demonstrated good adherence to assigned ventilation mode and the ability to meet a priori protocol compliance criteria. Exploratory outcomes suggest some clinical benefit for NAVA compared to PSV. Clinical effectiveness trials of NAVA are potentially feasible and warranted. Trial registration ClinicalTrials.gov , NCT01826890 . Registered 9 April 2013.

In mechanically ventilated patients, measurement of respiratory system compliance (Crs) is of high clinical interest. Spontaneous breathing activity during pressure support ventilation (PSV) can impede the correct assessment of Crs and also alter the true Crs by inducing lung recruitment. We describe a method for determination of Crs during PSV and assess its accuracy in a study on 20 mechanically ventilated patients. To assess Crs during pressure support ventilation (Crs,PSV), we performed repeated changes in pressure support level by ± 2 cmH2O. Crs,PSV was calculated from the volume change induced by these changes in pressure support level, taking into account the inspiration time and the expiratory time constant. As reference methods, we used Crs, measured during volume controlled ventilation (Crs,VCV). In a post-hoc analysis, we assessed Crs during the last 20% of the volume-controlled inflation (Crs,VCV20). Values were compared by linear regression and Bland–Altman methods comparison. Comparing Crs,PSV to the reference value Crs,VCV, we found a coefficient of determination (r2) of 0.90, but a relatively high bias of − 7 ml/cm H2O (95% limits of agreement − 16.7 to + 2.7 ml/cmH2O). Comparison with Crs,VCV20 resulted in a negligible bias (− 1.3 ml/cmH2O, 95% limits of agreement − 13.9 to + 11.3) and r2 of 0.81. We conclude that the novel method provides an estimate of end-inspiratory Crs during PSV. Despite its limited accuracy, it might be useful for non-invasive monitoring of Crs in patients undergoing pressure support 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 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.

Background Noninvasive ventilation (NIV) is generally delivered using pneumatically-triggered and cycled-off pressure support (PS P ) through a mask. Neurally adjusted ventilatory assist (NAVA) is the only ventilatory mode that uses a non-pneumatic signal, i.e., diaphragm electrical activity (EAdi), to trigger and drive ventilator assistance. A specific setting to generate neurally controlled pressure support (PS N ) was recently proposed for delivering NIV by helmet. We compared PS N with PS P and NAVA during NIV using a facial mask, with respect to patient comfort, gas exchange, and patient-ventilator interaction and synchrony. Methods Three 30-minute trials of NIV were randomly delivered to 14 patients immediately after extubation to prevent post-extubation respiratory failure: (1) PS P , with an inspiratory support ≥8 cmH 2 O; (2) NAVA, adjusting the NAVA level to achieve a comparable peak EAdi (EAdi peak ) as during PS P ; and (3) PS N , setting the NAVA level at 15 cmH 2 O/μV with an upper airway pressure (Paw) limit to obtain the same overall Paw applied during PS P . We assessed patient comfort, peak inspiratory flow (PIF), time to reach PIF (PIF time ), EAdi peak , arterial blood gases, pressure-time product of the first 300 ms (PTP 300-index ) and 500 ms (PTP 500-index ) after initiation of patient effort, inspiratory trigger delay (Delay TR-insp ), and rate of asynchrony, determined as asynchrony index (AI%). The categorical variables were compared using the McNemar test, and continuous variables by the Friedman test followed by the Wilcoxon test with Bonferroni correction for multiple comparisons ( p  < 0.017). Results PS N significantly improved patient comfort, compared to both PS P ( p  = 0.001) and NAVA ( p  = 0.002), without differences between the two latter ( p  = 0.08). PIF ( p  = 0.109), EAdi peak ( p  = 0.931) and gas exchange were similar between modes. Compared to PS P and NAVA, PS N reduced PIF time ( p  < 0.001), and increased PTP 300-index ( p  = 0.004) and PTP 500-index ( p  = 0.001). NAVA and PS N significantly reduced Delay TR-insp , as opposed to PS P ( p  < 0.001). During both NAVA and PS N , AI% was <10% in all patients, while AI% was ≥10% in 7 patients (50%) with PS P ( p  = 0.023 compared with both NAVA and PS N ). Conclusions Compared to both PS P and NAVA, PS N improved comfort and patient-ventilator interaction during NIV by facial mask. PS N also improved synchrony, as opposed to PS P only. Trial registration ClinicalTrials.gov, NCT03041402 . Registered (retrospectively) on 2 February 2017.

Background Neurally adjusted ventilatory assist (NAVA) is a mode of mechanical ventilation that delivers oxygen pressures in proportion to electrical signals of the diaphragm. The proportional assistance can be adjusted by the clinician to reduce the patient’s work of breathing. Several case series of infants with congenital diaphragmatic hernias (CDH) have shown that NAVA may reduce oxygenation index and mean airway pressures. To date, no clinical trial has compared NAVA to standard methods of mechanical ventilation for babies with CDH. Methods The aim of this dual-centre randomised cross-over trial is to compare post-operative NAVA with assist control ventilation (ACV) for infants with CDH. If eligible, infants will be enrolled for a ventilatory support tolerance trial (VSTT) to assess their suitability for randomisation. If clinically stable during the VSTT, infants will be randomised to receive either NAVA or ACV first in a 1:1 ratio for a 4-h period. The oxygenation index, respiratory severity score and cumulative sedative medication use will be measured. Discussion Retrospective studies comparing NAVA to ACV in neonates with congenital diaphragmatic hernia have shown the ventilatory mode may improve respiratory parameters and benefit neonates. To our knowledge, this is the first prospective cross-over trial comparing NAVA to ACV. Trial registration NAN-C was prospectively registered on ClinicalTrials.gov NCT05839340  Registered on May 2023

Background Proportional assist ventilation with load-adjustable gain factors (PAV+) is a mechanical ventilation mode that delivers assistance to breathe in proportion to the patient’s effort. The proportional assistance, called the gain, can be adjusted by the clinician to maintain the patient’s respiratory effort or workload within a normal range. Short-term and physiological benefits of this mode compared to pressure support ventilation (PSV) include better patient-ventilator synchrony and a more physiological response to changes in ventilatory demand. Methods The objective of this multi-centre randomized controlled trial (RCT) is to determine if, for patients with acute respiratory failure, ventilation with PAV+ will result in a shorter time to successful extubation than with PSV. This multi-centre open-label clinical trial plans to involve approximately 20 sites in several continents. Once eligibility is determined, patients must tolerate a short-term PSV trial and either (1) not meet general weaning criteria or (2) fail a 2-min Zero Continuous Positive Airway Pressure (CPAP) Trial using the rapid shallow breathing index, or (3) fail a spontaneous breathing trial (SBT), in this sequence. Then, participants in this study will be randomized to either PSV or PAV+ in a 1:1 ratio. PAV+ will be set according to a target of muscular pressure. The weaning process will be identical in the two arms. Time to liberation will be the primary outcome; ventilator-free days and other outcomes will be measured. Discussion Meta-analyses comparing PAV+ to PSV suggest PAV+ may benefit patients and decrease healthcare costs but no powered study to date has targeted the difficult to wean patient population most likely to benefit from the intervention, or used consistent timing for the implementation of PAV+. Our enrolment strategy, primary outcome measure, and liberation approaches may be useful for studying mechanical ventilation and weaning and can offer important results for patients. Trial registration ClinicalTrials.gov NCT02447692 . Prospectively registered on May 19, 2015.

Background Patient-ventilator asynchrony is a common problem in mechanically ventilated patients with acute respiratory failure. It is assumed that asynchronies worsen lung function and prolong the duration of mechanical ventilation (MV). Neurally Adjusted Ventilatory Assist (NAVA) is a novel approach to MV based on neural respiratory center output that is able to trigger, cycle, and regulate the ventilatory cycle. We hypothesized that the use of NAVA compared to conventional lung-protective MV will result in a reduction of the duration of MV. It is further hypothesized that NAVA compared to conventional lung-protective MV will result in a decrease in the length of ICU and hospital stay, and mortality. Methods/design This is a prospective, multicenter, randomized controlled trial in 306 mechanically ventilated patients with acute respiratory failure from several etiologies. Only patients ventilated for less than 5 days, and who are expected to require prolonged MV for an additional 72 h or more and are able to breathe spontaneously, will be considered for enrollment. Eligible patients will be randomly allocated to two ventilatory arms: (1) conventional lung-protective MV ( n  = 153) and conventional lung-protective MV with NAVA ( n  = 153). Primary outcome is the number of ventilator-free days, defined as days alive and free from MV at day 28 after endotracheal intubation. Secondary outcomes are total length of MV, and ICU and hospital mortality. Discussion This is the first randomized clinical trial examining, on a multicenter scale, the beneficial effects of NAVA in reducing the dependency on MV of patients with acute respiratory failure. Trial registration ClinicalTrials.gov website ( NCT01730794 ). Registered on 15 November 2012.