Neurally adjusted ventilatory assist improves patient–ventilator interaction during postextubation prophylactic noninvasive ventilation* (original) (raw)
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BMC Anesthesiology, 2015
Background: Weaning from mechanical ventilation is associated with the presence of asynchronies between the patient and the ventilator. The main objective of the present study was to demonstrate a decrease in the total number of patient-ventilator asynchronies in invasively ventilated patients for whom difficulty in weaning is expected by comparing neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) ventilatory modes. Methods: We performed a prospective, non-randomized, non-interventional, single-center study. Thirty patients were included in the study. Each patient included in the study benefited in an unpredictable way from both modes of ventilation, NAVA or PSV. Patients were successively ventilated for 23 h in NAVA or in PSV, and then they were ventilated for another 23 h in the other mode. Demographic, biological and ventilatory data were collected during this period. The two modes of ventilatory support were compared using the non-parametric Wilcoxon test after checking for normal distribution by the Kolmogorov-Smirnov test. The groups were compared using the chi-square test. Results: The median level of support was 12.5 cmH 2 O (4-20 cmH 2 O) in PSV and 0.8 cmH 2 O/μvolts (0.2-3 cmH 2 O/μvolts) in NAVA. The total number of asynchronies per minute in NAVA was lower than that in PSV (0.46 vs 1, p < 0.001). The asynchrony index was also reduced in NAVA compared with PSV (1.73 vs 3.36, p < 0.001). In NAVA, the percentage of ineffective efforts (0.77 vs 0.94, p = 0.036) and the percentage of auto-triggering were lower compared with PSV (0.19 vs 0.71, p = 0.038). However, there was a higher percentage of double triggering in NAVA compared with PSV (0.76 vs 0.71, p = 0.046). Conclusion: The total number of asynchronies in NAVA is lower than that in PSV. This finding reflects improved patient-ventilator interaction in NAVA compared with the PSV mode, which is consistent with previous studies. Our study is the first to analyze patient-ventilator asynchronies in NAVA and PSV on such an important duration. The decrease in the number of asynchronies in NAVA is due to reduced ineffective efforts and auto-triggering.
To determine if, compared to pressure support (PS), neurally adjusted ventilatory assist (NAVA) reduces patient-ventilator asynchrony in intensive care patients undergoing noninvasive ventilation with an oronasal face mask. In this prospective interventional study we compared patient-ventilator synchrony between PS (with ventilator settings determined by the clinician) and NAVA (with the level set so as to obtain the same maximal airway pressure as in PS). Two 20-min recordings of airway pressure, flow and electrical activity of the diaphragm during PS and NAVA were acquired in a randomized order. Trigger delay (T(d)), the patient&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s neural inspiratory time (T(in)), ventilator pressurization duration (T(iv)), inspiratory time in excess (T(iex)), number of asynchrony events per minute and asynchrony index (AI) were determined. The study included 13 patients, six with COPD, and two with mixed pulmonary disease. T(d) was reduced with NAVA: median 35 ms (IQR 31-53 ms) versus 181 ms (122-208 ms); p = 0.0002. NAVA reduced both premature and delayed cyclings in the majority of patients, but not the median T(iex) value. The total number of asynchrony events tended to be reduced with NAVA: 1.0 events/min (0.5-3.1 events/min) versus 4.4 events/min (0.9-12.1 events/min); p = 0.08. AI was lower with NAVA: 4.9 % (2.5-10.5 %) versus 15.8 % (5.5-49.6 %); p = 0.03. During NAVA, there were no ineffective efforts, or late or premature cyclings. PaO(2) and PaCO(2) were not different between ventilatory modes. Compared to PS, NAVA improved patient ventilator synchrony during noninvasive ventilation by reducing T(d) and AI. Moreover, with NAVA, ineffective efforts, and late and premature cyclings were absent.
Open Access Macedonian Journal of Medical Sciences, 2021
BACKGROUND: Patient-mechanical ventilator (MV) asynchrony despite optimal adjustment of MV parameters is a common problem that is partly associated with difficult weaning of MV. Neurally adjusted ventilatory assist (NAVA) is a mode of proportional ventilation that count on diaphragmatic activity (measured by special esophageal probe and expressed as diaphragm electrical [Edi]) to provide proportional support to patient effort which differs from one breath to another according to Edi signal. AIM: The purpose of this trial is to determine the impact of NAVA compared to pressure support ventilation (PSV) mode in decreasing patient-MV asynchrony and hemodynamic effect in patients on MV with expected difficult weaning. MATERIALS AND METHODS: This prospective interventional trial was conducted on 30 critically ill on MV with expected difficult weaning. First, patients were put on PSV mode for 24 h. Then, patients were put on NAVA mode (for weaning) for the next 24 h. The incidence of diff...
Intensive Care Medicine, 2009
Objective: Air leaks around the mask are very likely to occur during noninvasive ventilation, in particular when prolonged ventilatory treatment is required. It has been suggested that leaks from the mask may impair the expiratory trigger cycling mechanism when inspiratory pressure support ventilation (PSV) is used. The aim of this study was to compare the short-term effect of two different expiratory cycling mechanisms (time-cycled vs flow-cycled) during noninvasive inspiratory pressure support ventilation (NIPSV) on patient-ventilator synchronisation in severe hypoxemic respiratory failure. Study population: Six patients with acute lung injury (ALI) due to acquired immunodeficiency syndrome (AIDS)-related opportunistic pneumonia were enrolled in the protocol. Intervention: Each subject was first studied during spontaneous breathing with a Venturi oxygen mask (SB) and successively submitted to a randomly assigned 20 ¢ conventional flow-cycling (NIPSVfc) or time-cycling inspiratory pressure support ventilation (NIPSVtc). The pre-set parameters were: inspiratory pressure of 10 cm H 2 O, PEEP of 5 cm H 2 O for the same inspired oxygen fraction as during SB. A tight fit of the mask was avoided in order to facilitate air leaks around the mask. The esophageal pressure time product (PTPes) and tidal swings (DPes) were measured to evaluate the patient's respiratory effort. A subjective ªcomfort scoreº and the difference between patient and machine respiratory rate [DRR(p-v)], calculated on esophageal and airway pressure curves, were used as indices of patient-machine interaction. Results: Air leaks through the mask occurred in five out of six patients. The values of PEEPi (< 1.9 cm H 2 0) excluded significant expiratory muscle activity. NIPSVtc significantly reduced PTPes, DPes, and DRR(p-v) when compared to NIPS-Vfc [230 41 (SE) vs 376 72 cm H 2 O × s × min ±1 ; 8 2 vs 13 2 cm H 2 O; 1 1 vs 9 2 br × min ±1 ; respectively] with a concomitant significant improvement of the ªcomfort scoreº. Conclusions: In the presence of air leaks a time-cycled expiratory trigger provides a better patient-machine interaction than a flow-cycled expiratory trigger during NIPSV.
Patient-ventilator asynchrony during noninvasive ventilation: the role of expiratory trigger
Intensive Care Medicine, 1999
Objective: Air leaks around the mask are very likely to occur during noninvasive ventilation, in particular when prolonged ventilatory treatment is required. It has been suggested that leaks from the mask may impair the expiratory trigger cycling mechanism when inspiratory pressure support ventilation (PSV) is used. The aim of this study was to compare the short-term effect of two different expiratory cycling mechanisms (time-cycled vs flow-cycled) during noninvasive inspiratory pressure support ventilation (NIPSV) on patient-ventilator synchronisation in severe hypoxemic respiratory failure. Study population: Six patients with acute lung injury (ALI) due to acquired immunodeficiency syndrome (AIDS)-related opportunistic pneumonia were enrolled in the protocol. Intervention: Each subject was first studied during spontaneous breathing with a Venturi oxygen mask (SB) and successively submitted to a randomly assigned 20 ′ conventional flow-cycling (NIPSVfc) or time-cycling inspiratory pressure support ventilation (NIPSVtc). The pre-set parameters were: inspiratory pressure of 10 cm H2O, PEEP of 5 cm H2O for the same inspired oxygen fraction as during SB. A tight fit of the mask was avoided in order to facilitate air leaks around the mask. The esophageal pressure time product (PTPes) and tidal swings (ΔPes) were measured to evaluate the patient's respiratory effort. A subjective “comfort score” and the difference between patient and machine respiratory rate [ΔRR(p-v)], calculated on esophageal and airway pressure curves, were used as indices of patient-machine interaction. Results: Air leaks through the mask occurred in five out of six patients. The values of PEEPi (< 1.9 cm H20) excluded significant expiratory muscle activity. NIPSVtc significantly reduced PTPes, ΔPes, and ΔRR(p-v) when compared to NIPSVfc [230 ± 41 (SE) vs 376 ± 72 cm H2O · s · min–1 ; 8 ± 2 vs 13 ± 2 cm H2O; 1 ± 1 vs 9 ± 2 br · min–1; respectively] with a concomitant significant improvement of the “comfort score”. Conclusions: In the presence of air leaks a time-cycled expiratory trigger provides a better patient-machine interaction than a flow-cycled expiratory trigger during NIPSV.
Pulmonary Medicine, 2020
Background. Noninvasive neurally adjusted ventilatory assist (NAVA) has been shown to improve patient-ventilator interaction in many settings. There is still scarce data with regard to postoperative patients indicated for noninvasive ventilation (NIV) which this study elates. The purpose of this trial was to evaluate postoperative patients for synchrony and comfort in noninvasive pressure support ventilation (NIV-PSV) vs. NIV-NAVA. Methods. Twenty-two subjects received either NIV-NAVA or NIV-PSV in an object-blind, prospective, randomized, crossover fashion (observational trial). We evaluated blood gases and ventilator tracings throughout as well as comfort of ventilation at the end of each ventilation phase. Results. There was an effective reduction in ventilator delays (p < 0:001) and negative pressure duration in NIV-NAVA as compared to NIV-PSV (p < 0:001). Although we used optimized settings in NIV-PSV, explaining the overall low incidence of asynchrony, NIV-NAVA led to reductions in the NeuroSync-index (p < 0:001) and all types of asynchrony except for double triggering that was significantly more frequent in NIV-NAVA vs. NIV-PSV (p = 0:02); ineffective efforts were reduced to zero by use of NIV-NAVA. In our population of previously lung-healthy subjects, we did not find differences in blood gases and patient comfort between the two modes. Conclusion. In the postoperative setting, NIV-NAVA is well suitable for use and effective in reducing asynchronies as well as a surrogate for work of breathing. Although increased synchrony was not transferred into an increased comfort, there was an advantage with regard to patient-ventilator interaction. The trial was registered at the German clinical Trials Register (DRKS no.: DRKS00005408).
Pediatric Critical Care Medicine, 2013
Objectives: To document the prevalence of asynchrony events during noninvasive ventilation in pressure support in infants and in children and to compare the results with neurally adjusted ventilatory assist. Design: Prospective randomized cross-over study in children undergoing noninvasive ventilation. Setting: The study was performed in a PICU. Patients: From 4 weeks to 5 years. Interventions: Two consecutive ventilation periods (pressure support and neurally adjusted ventilatory assist) were applied in random order. During pressure support (PS), three levels of expiratory trigger (ETS) setting were compared: initial ETS (PSinit), and ETS value decreased and increased by 15%. Of the three sessions, the period allowing for the lowest number of asynchrony events was defined as PSbest. Neurally adjusted ventilator assist level was adjusted to match the maximum airway pressure during PSinit. Positive end-expiratory pressure was the same during pressure support and neurally adjusted ventilator assist. Asynchrony events, trigger delay, and cycling-off delay were quantified for each period.
Intensive Care Medicine, 2010
Objective: To evaluate patient-ventilator interaction during pressure support ventilation (PSV) delivered with three interfaces [endotracheal tube (ET), face mask (FM), and helmet (H)] at different pressurization times (Time press ), cycling-off flow thresholds (Tr exp ), and respiratory rates (RR) in a bench study, and with FM and H in a healthy volunteers study. Design: Bench study using a mannequin connected to an active lung simulator, and human study including eight healthy volunteers. Measurements: PSV was delivered through the three interfaces with three different RR in the bench study, and through FM and H at two different RR in the human study. The mechanical and the neural RR, Ti, Te, inspiratory trigger delay (Delay trinsp ), pressurization time, and expiratory trigger delay were randomly evaluated at various ventilator settings (Time press /Tr exp : 50%/25%, default setting; 20%/5%, slow setting; 80%/ 60%, fast setting). Results: Bench study: patient-ventilator synchrony was significantly better with ET, with lower Delay trinsp and higher time of assistance (P \ 0.001); the combination Time press /Tr exp 20%/5% at RR 30 produced the worst interaction, with higher rate of wasted efforts (WE) compared with Time press /Tr exp 80%/60% (20%, 40%, and 50% of WE versus 0%, 16%, and 26% of all spontaneous breaths, with ET, FM, and H, respectively; P \ 0.01). In both studies, compared with H, FM resulted in better synchrony. Conclusion: Patient-ventilator synchrony was significantly better with ET during the bench study; in the human study, FM outperformed H.
Annals of Thoracic Medicine, 2019
Patient-ventilator asynchrony (PVA) is common in patients receiving noninvasive ventilation (NIV). This occurs primarily when the triggering and cycling-off of ventilatory assistance are not synchronized with the patient's inspiratory efforts and could result in increased work of breathing and niv failure. In general, five types of asynchrony can occur during NIV: ineffective inspiratory efforts, double-triggering, auto-triggering, short-ventilatory cycling, and long-ventilatory cycling. Many factors that affect PVA are mostly related to the degree of air leakage, level of pressure support, and the type and properties of the interface used. Careful monitoring and adjustment of these factors are essential to reduce PVA and improve patient comfort. In this article, we discuss the machine and interface-related factors that influence PVA during NIV and its effect on the respiratory mechanics during pressure support ventilation, which is the ventilatory mode used most commonly during NIV. For that, we critically evaluated studies that assessed ventilator-and interface-related factors that influence PVA during NIV and proposed therapeutic solutions.