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Neurally adjusted ventilatory assist and proportional assist ventilation both improve patient-ventilator interaction.

ABSTRACT: The objective was to compare the impact of three assistance levels of different modes of mechanical ventilation; neurally adjusted ventilatory assist (NAVA), proportional assist ventilation (PAV), and pressure support ventilation (PSV) on major features of patient-ventilator interaction.PSV, NAVA, and PAV were set to obtain a tidal volume (VT) of 6 to 8 ml/kg (PSV???, NAVA???, and PAV???) in 16 intubated patients. Assistance was further decreased by 50% (PSV??, NAVA??, and PAV??) and then increased by 50% (PSV???, NAVA???, and PAV???) with all modes. The three modes were randomly applied. Airway flow and pressure, electrical activity of the diaphragm (EAdi), and blood gases were measured. VT, peak EAdi, coefficient of variation of VT and EAdi, and the prevalence of the main patient-ventilator asynchronies were calculated.PAV and NAVA prevented the increase of VT with high levels of assistance (median 7.4 (interquartile range (IQR) 5.7 to 10.1) ml/kg and 7.4 (IQR, 5.9 to 10.5) ml/kg with PAV??? and NAVA??? versus 10.9 (IQR, 8.9 to 12.0) ml/kg with PSV???, P <0.05). EAdi was higher with PAV than with PSV at level??? and level???. The coefficient of variation of VT was higher with NAVA and PAV (19 (IQR, 14 to 31)% and 21 (IQR 16 to 29)% with NAVA??? and PAV??? versus 13 (IQR 11 to 18)% with PSV???, P <0.05). The prevalence of ineffective triggering was lower with PAV and NAVA than with PSV (P <0.05), but the prevalence of double triggering was higher with NAVA than with PAV and PSV (P <0.05).PAV and NAVA both prevent overdistention, improve neuromechanical coupling, restore the variability of the breathing pattern, and decrease patient-ventilator asynchrony in fairly similar ways compared with PSV. Further studies are needed to evaluate the possible clinical benefits of NAVA and PAV on clinical outcomes.Clinicaltrials.gov NCT02056093 . Registered 18 December 2013.

SUBMITTER: Schmidt M

PROVIDER: S-EPMC4355459 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

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Neurally adjusted ventilatory assist and proportional assist ventilation both improve patient-ventilator interaction.

Schmidt Matthieu M Kindler Felix F Cecchini Jérôme J Poitou Tymothée T Morawiec Elise E Persichini Romain R Similowski Thomas T Demoule Alexandre A

Critical care (London, England) 20150225

<h4>Introduction</h4>The objective was to compare the impact of three assistance levels of different modes of mechanical ventilation; neurally adjusted ventilatory assist (NAVA), proportional assist ventilation (PAV), and pressure support ventilation (PSV) on major features of patient-ventilator interaction.<h4>Methods</h4>PSV, NAVA, and PAV were set to obtain a tidal volume (VT) of 6 to 8 ml/kg (PSV₁₀₀, NAVA₁₀₀, and PAV₁₀₀) in 16 intubated patients. Assistance was further decreased by 50% (PSV₅ ...[more]

PMID: 25879592

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Project description:Assist in unison to the patient's inspiratory neural effort and feedback-controlled limitation of lung distension with neurally adjusted ventilatory assist (NAVA) may reduce the negative effects of mechanical ventilation on right ventricular function.Heart-lung interaction was evaluated in 10 intubated patients with impaired cardiac function using esophageal balloons, pulmonary artery catheters and echocardiography. Adequate NAVA level identified by a titration procedure to breathing pattern (NAVAal), 50% NAVAal, and 200% NAVAal and adequate pressure support (PSVal, defined clinically), 50% PSVal, and 150% PSVal were implemented at constant positive end-expiratory pressure for 20 minutes each.NAVAal was 3.1?±?1.1cmH2O/?V and PSVal was 17?±?2 cmH20. For all NAVA levels negative esophageal pressure deflections were observed during inspiration whereas this pattern was reversed during PSVal and PSVhigh. As compared to expiration, inspiratory right ventricular outflow tract velocity time integral (surrogating stroke volume) was 103?±?4%, 109?±?5%, and 100?±?4% for NAVAlow, NAVAal, and NAVAhigh and 101?±?3%, 89?±?6%, and 83?±?9% for PSVlow, PSVal, and PSVhigh, respectively (p?<?0.001 level-mode interaction, ANOVA). Right ventricular systolic isovolumetric pressure increased from 11.0?±?4.6 mmHg at PSVlow to 14.0?±?4.6 mmHg at PSVhigh but remained unchanged (11.5?±?4.7 mmHg (NAVAlow) and 10.8?±?4.2 mmHg (NAVAhigh), level-mode interaction p?=?0.005). Both indicate progressive right ventricular outflow impedance with increasing pressure support ventilation (PSV), but no change with increasing NAVA level.Right ventricular performance is less impaired during NAVA compared to PSV as used in this study. Proposed mechanisms are preservation of cyclic intrathoracic pressure changes characteristic of spontaneous breathing and limitation of right-ventricular outflow impedance during inspiration, regardless of the NAVA level.Clinicaltrials.gov Identifier: NCT00647361, registered 19 March 2008.

Project description:BACKGROUND:Effective synchronisation of infant respiratory effort with mechanical ventilation may allow adequate gas exchange to occur at lower peak airway pressures, potentially reducing barotrauma and volutrauma and development of air leaks and bronchopulmonary dysplasia. During neurally adjusted ventilatory assist ventilation (NAVA), respiratory support is initiated upon detection of an electrical signal from the diaphragm muscle, and pressure is provided in proportion to and synchronous with electrical activity of the diaphragm (EADi). Compared to other modes of triggered ventilation, this may provide advantages in improving synchrony. OBJECTIVES:Primary• To determine whether NAVA, when used as a primary or rescue mode of ventilation, results in reduced rates of bronchopulmonary dysplasia (BPD) or death among term and preterm newborn infants compared to other forms of triggered ventilation• To assess the safety of NAVA by determining whether it leads to greater risk of intraventricular haemorrhage (IVH), periventricular leukomalacia, or air leaks when compared to other forms of triggered ventilation Secondary• To determine whether benefits of NAVA differ by gestational age (term or preterm)• To determine whether outcomes of cross-over trials performed during the first two weeks of life include peak pressure requirements, episodes of hypocarbia or hypercarbia, oxygenation index, and the work of breathing SEARCH METHODS: We performed searches of the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cohrane Library; MEDLINE via Ovid SP (January 1966 to March 2017); Embase via Ovid SP (January 1980 to March 2017); the Cumulative Index to Nursing and Allied Health Literature (CINAHL) via EBSCO host (1982 to March 2017); and the Web of Science (1985 to 2017). We searched abstracts from annual meetings of the Pediatric Academic Societies (PAS) (2000 to 2016); meetings of the European Society of Pediatric Research (published in Pediatric Research); and meetings of the Perinatal Society of Australia and New Zealand (PSANZ) (2005 to 2016). We also searched clinical trials databases to March 2017. SELECTION CRITERIA:We included randomised and quasi-randomised clinical trials including cross-over trials comparing NAVA with other modes of triggered ventilation (assist control ventilation (ACV),synchronous intermittent mandatory ventilation plus pressure support (SIMV ± PS), pressure support ventilation (PSV), or proportional assist ventilation (PAV)) used in neonates. DATA COLLECTION AND ANALYSIS:Primary outcomes of interest from randomised controlled trials were all-cause mortality, bronchopulmonary dysplasia (BPD; defined as oxygen requirement at 28 days), and a combined outcome of all-cause mortality or BPD. Secondary outcomes were duration of mechanical ventilation, incidence of air leak, incidence of IVH or periventricular leukomalacia, and survival with an oxygen requirement at 36 weeks' postmenstrual age.Outcomes of interest from cross-over trials were maximum fraction of inspired oxygen, mean peak inspiratory pressure, episodes of hypocarbia, and episodes of hypercarbia measured across the time period of each arm of the cross-over. We planned to assess work of breathing; oxygenation index, and thoraco-abdominal asynchrony at the end of the time period of each arm of the cross-over study. MAIN RESULTS:We included one randomised controlled study comparing NAVA versus patient-triggered time-cycled pressure-limited ventilation. This study found no significant difference in duration of mechanical ventilation, nor in rates of BPD, pneumothorax, or IVH. AUTHORS' CONCLUSIONS:Risks and benefits of NAVA compared to other forms of ventilation for neonates are uncertain. Well-designed trials are required to evaluate this new form of triggered ventilation.

Project description:Neurally Adjusted Ventilatory Assist (NAVA) is a mode of assisted mechanical ventilation that delivers inspiratory pressure proportionally to the electrical activity of the diaphragm. To date, no pediatric study has focused on the effects of NAVA on hemodynamic parameters. This physiologic study with a randomized cross-over design compared hemodynamic parameters when NAVA or conventional ventilation (CV) was applied.After a baseline period, infants received NAVA and CV in a randomized order during two consecutive 30-min periods. During the last 10 min of each period, respiratory and hemodynamic parameters were collected. No changes in PEEP, FiO2, sedation or inotropic doses were allowed during these two periods. The challenge was to keep minute volumes constant, with no changes in blood CO2 levels and in pH that may affect the results.Six infants who had undergone cardiac surgery (mean age 7.8?±?4.1 months) were studied after parental consent. Four of them had low central venous oxygen saturation (ScvO2?<?65 %). The ventilatory settings resulted in similar minute volumes (1.7?±?0.4 vs. 1.6?±?0.6 ml/kg, P?=?0.67) and in similar tidal volumes respectively with NAVA and with CV. There were no statistically significant differences on blood pH levels between the two modes of ventilation (7.32?±?0.02 vs. 7.32?±?0.04, P?=?0.34). Ventilation with NAVA delivered lower peak inspiratory pressures than with CV: -32.7 % (95 % CI: -48.2 to -17.1 %, P?=?0.04). With regard to hemodynamics, systolic arterial pressures were higher using NAVA: +8.4 % (95 % CI: +3.3 to +13.6 %, P?=?0.03). There were no statistically significant differences on cardiac index between the two modes of ventilation. However, all children with a low baseline ScvO2 (<65 %) tended to increase their cardiac index with NAVA compared to CV: 2.03?±?0.30 vs. 1.91?±?0.39 L/min.m2 (median?±?interquartile, P?=?0.07).This pilot study raises the hypothesis that NAVA could have beneficial effects on hemodynamics in children when compared to a conventional ventilatory mode that delivered identical PEEP and similar minute volumes.ClinicalTrials.gov Identifier: NCT01490710 . Date of registration: December 7, 2011.

Project description:IntroductionWe previously showed in animals that the ratio of inspired tidal volume (Vtinsp) to inspiratory peak electrical activity of the diaphragm (EAdipk) can be used to quantify the respective patient and ventilator breath contributions (PVBCs) during neurally adjusted ventilatory assist (NAVA). The PVBC index has not been tested clinically.MethodsWe studied 12 intubated and mechanically ventilated patients with acute respiratory failure and measured EAdipk, airway (Paw) and inspiratory esophageal pressure (Pes) and Vtinsp. We applied 11 different NAVA levels, increasing them every 3 minutes in steps of 0.3 cm H₂O/μV from 0 to 3.0 cmH₂O/μV. At each NAVA level, one breath was non-assisted (NAVA level 0). PVBC indices were calculated by relating Vtinsp/EAdipk of the non-assisted breath to Vtinsp/EAdipk of the assisted breath(s) using one ((N1)PVBC) or the mean value of five preceding assisted breaths ((X5)PVBC). During assisted breaths, inspiratory changes in Pes (∆Pes) and transpulmonary (ΔPtp) pressures were used to calculate the relative contribution of patient to total inspiratory lung-distending pressures (ΔPes/ΔPtp). Matching of respiratory drive indices and squaring of the PVBC was evaluated for their effect on the correlation between PVBC and ΔPes/ΔPtp. Linear regression analysis and Bland-Altman analysis were applied to compare indices.ResultsUsing an average of five assisted breaths prior to the non-assisted breath and squaring the PVBC ((X5)PVBC(2)) improved determination coefficients (P <0.05), adjusted the regression slope and intercept between PVBC and ΔPes/ΔPtp toward identity (P <0.05) and reduced bias (P <0.05). Matching EAdipk between non-assisted and assisted breaths within the range of 0.77 to 1.30 improved the relationship between (X5)PVBC(2) and ΔPes/ΔPtp (P <0.05) and abolished the need for EAdi normalization in the PVBC calculation (R(2) = 0.96; bias = 0.16 ± 0.06; precision = 0.33 ± 0.08 (mean and 95% confidence interval)).ConclusionsThis clinical study confirms previous experimental results showing that the PVBC(2) predicts the contribution of the inspiratory muscles versus that of the ventilator during NAVA, when differences in effort (EAdi) between non-assisted and assisted breaths are limited. PVBC could help to quantify and standardize the adjustment of the level of assist, and hence reduce the risks of excessive ventilatory assist in patients.Trial registrationClinicalTrials.gov NCT01663480. Registered 9 August 2012.

Project description:Noninvasive ventilation (NIV) is generally delivered using pneumatically-triggered and cycled-off pressure support (PSP) 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 (PSN) was recently proposed for delivering NIV by helmet. We compared PSN with PSP and NAVA during NIV using a facial mask, with respect to patient comfort, gas exchange, and patient-ventilator interaction and synchrony.Three 30-minute trials of NIV were randomly delivered to 14 patients immediately after extubation to prevent post-extubation respiratory failure: (1) PSP, with an inspiratory support ?8 cmH2O; (2) NAVA, adjusting the NAVA level to achieve a comparable peak EAdi (EAdipeak) as during PSP; and (3) PSN, setting the NAVA level at 15 cmH2O/?V with an upper airway pressure (Paw) limit to obtain the same overall Paw applied during PSP. We assessed patient comfort, peak inspiratory flow (PIF), time to reach PIF (PIFtime), EAdipeak, arterial blood gases, pressure-time product of the first 300 ms (PTP300-index) and 500 ms (PTP500-index) after initiation of patient effort, inspiratory trigger delay (DelayTR-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).PSN significantly improved patient comfort, compared to both PSP (p?=?0.001) and NAVA (p?=?0.002), without differences between the two latter (p?=?0.08). PIF (p?=?0.109), EAdipeak (p?=?0.931) and gas exchange were similar between modes. Compared to PSP and NAVA, PSN reduced PIFtime (p?<?0.001), and increased PTP300-index (p?=?0.004) and PTP500-index (p?=?0.001). NAVA and PSN significantly reduced DelayTR-insp, as opposed to PSP (p?<?0.001). During both NAVA and PSN, AI% was <10% in all patients, while AI% was ?10% in 7 patients (50%) with PSP (p?=?0.023 compared with both NAVA and PSN).Compared to both PSP and NAVA, PSN improved comfort and patient-ventilator interaction during NIV by facial mask. PSN also improved synchrony, as opposed to PSP only.ClinicalTrials.gov, NCT03041402 . Registered (retrospectively) on 2 February 2017.

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Neurally adjusted ventilatory assist and proportional assist ventilation both improve patient-ventilator interaction.

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Neurally adjusted ventilatory assist and proportional assist ventilation both improve patient-ventilator interaction.

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