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Background: Because of inherent leaks, obtaining good patient–ventilator synchrony during non-invasive ventilation (NIV) is challenging. The IntelliSync + ® software (Hamilton medical, Bonaduz, CH), that can be used together with the NIV mode, performs real-time automated analysis of airway pressure- and flow-time curves to detect the transition between inspiration and expiration. It then controls the ventilator inspiratory and expiratory valves to improve patient–ventilator synchrony. The main goal of this NIV bench study was to evaluate the impact of IntelliSync + ® on synchrony in the presence of leaks of 9 and 20 L/min in the tested ventilator circuit (no face mask used), with normal, obstructive and restrictive respiratory mechanics and two levels of NIV pressure support (PS 8 and 14 cmH2O). For this, the time needed to trigger the ventilator (Td) and the difference between the end of the simulated breath and the termination of pressurization (Tiex) were measured. The number of classical asynchronies and the ventilator pressurization capacity were also assessed. Results: Compared to NIV delivered with the classical NIV mode (compensating leaks and limiting inspiratory time to 2 s), activating IntelliSync + ® improved Tiex and, to a lesser extent, Td in clinically relevant setups. IntelliSync + ® also showed a trend towards reducing classical asynchronies, particularly directly after leak flow increase. The impact of the system was most significant with high PS levels and pathological respiratory mechanics. Especially, in the obstructive model, in the presence of large leak (20 L/min) and PS 14 cmH2O, Tiex decreased from 0.61 [0.56–0.64] to 0.16 [0.07–0.18] s and Td from 0.07 [0.06–0.08] to 0.06 [0.06–0.08] s. In less challenging situations, IntelliSync + ® was less beneficial. Overall, ventilator pressurization was improved when IntelliSync + ® was activated. Conclusions: In this NIV bench model, IntelliSync + ®, used in addition to NIV-PS, improved both expiratory and inspiratory synchrony. It was particularly efficient in the presence of obstructive and restrictive respiratory mechanics and high-pressure support levels. These pre-clinical results tend to support the ability of IntelliSync + ® to improve patient–ventilator synchrony in the presence of leaks and provide pre-clinical data supporting a clinical evaluation of the automated algorithm during NIV. [ABSTRACT FROM AUTHOR]

This meta-analysis aims to evaluate the effectiveness of adaptive support ventilation (ASV) in facilitating postoperative weaning from mechanical ventilation in cardiac surgery patients. A systematic review and meta-analysis to assess ASV in weaning postoperative cardiac surgery patients. Outcomes included early extubation, reintubation rates, time to extubation, and lengths of intensive care units and hospital stays. We searched electronic databases from inception to March 2023 and included randomized controlled trials that compared ASV with conventional ventilation methods in this population. Postoperative cardiac surgery patients. A random effects model was used for meta-analysis, and trial sequential analysis (TSA) was conducted to assess result robustness. The meta-analysis included 11 randomized controlled trials with a total of 1027 randomized patients. ASV was associated with a shorter time to extubation compared to conventional ventilation (random effects, mean difference –68.30 hours; 95% confidence interval, –115.50 to –21.09) with TSA providing a conclusive finding. While ASV indicated improved early extubation rates, no significant differences were found in reintubation rates or lengths of intensive care unit and hospital stays, with these TSA results being inclusive. ASV appears to facilitate a shorter time to extubation in postoperative cardiac surgery patients compared to conventional ventilation, suggesting benefits in accelerating the weaning process and reducing mechanical ventilation duration. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract 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 240/7–276/7 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 24–276/7 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 FiO2 at least 20% from pre-extubation for > 2 h, (2) pH ≤ 7.20 or pCO2 ≥ 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: 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 240/7–276/7 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 24–276/7 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 FiO2 at least 20% from pre-extubation for > 2 h, (2) pH ≤ 7.20 or pCO2 ≥ 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: , trial identifier , registered July 6, 2022. [ABSTRACT FROM AUTHOR]

Background: Mechanical ventilation in preterm neonates aims for synchrony, preventing complications such as lung injury. Neurally Adjusted Ventilatory Assist (NAVA) is a unique mode relying on diaphragmatic electrical signals for synchronization. We conducted a review focusing on the long-term consequences of using invasive NAVA in neonates with a focus on bronchopulmonary dysplasia (BPD). Methods: A systematic review following PRISMA explored invasive NAVA in preterm neonates. Primary objectives compared NAVA to conventional ventilation, assessing BPD incidence, ventilation duration, length of stay, and adverse events. Secondary objectives analyzed ventilator parameters. Results: After screening 282 records, the review incorporated two randomized controlled trials for primary outcomes and seven trials for secondary outcomes, including two randomized crossovers, four prospective crossovers, and one retrospective study. NAVA showed reduced oxygen requirement at 28 days but no significant differences in oxygen need at 36 weeks postmenstrual age, total length of stay, or ventilator days. Substantial variations were not observed in adverse events. Ventilator variables favored NAVA, indicating decreased peak inspiratory pressure, tidal volume, work of breathing, and respiratory severity score. Conclusion: Our study found no significant reduction in BPD with NAVA despite short-term benefits. Future large-scale trials are essential to assess NAVA's impact on long-term outcomes comprehensively. [ABSTRACT FROM AUTHOR]

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Introduction Non-invasive ventilation (NIV) has a significant role in supporting patients with respiratory failure with the goal of avoiding mechanical ventilation. Traditionally, NIV has been applied using dedicated NIV-specific devices but over the last decade, newer generation critical care ventilators have updated their capabilities to include NIV options with improved synchrony and leak compensation. No recent trials have compared the efficacy of new generation critical care ventilators to NIV ventilators. The purpose of this study was to evaluate clinicians attitudes and perceptions toward the use of NIV between the dedicated NIV and critical care ventilators. Methods An online survey of clinicians with seven questions regarding their thoughts and experience in using NIV in acute care settings was posted online and promoted through emails and social media. The survey was anonymous and an exemption of consent was obtained from the Institutional Review Board. Analysis of variants (ANOVA) was done for the total responses in each question, followed by multivariate analysis of variants (MANOVA) for responses per occupation. Results 514 responses from 54 countries were recorded. 151 from North America, 109 from South America, 125 from Europe, 97 from Asia, 21 from Africa, and 11 from Australia. 218 responders were physicians, 218 were respiratory therapists, 28 were nurses, and 50 were reported as other professionals (engineers, biomedical technicians). 346 (67.3%) reported using both types of ventilators for NIV, 91 (17.7%) use only NIV -specific devices, and 77 (15%) only use critical care ventilators (P 0.097), responses per occupation (P < 0.001). 290 (56.4%) have automatic synchronization software on either of their ventilators, 113 (22%) do not, while 111 (21.6%) are unsure if they do (P 0.22), with significant variation by occupation (P 0.008). Regarding synchrony, 233 (45.3%) said NIV ventilators are better, and 165 (32.1%) said critical care ventilators are better, while 116 (22.5%) said both are similar (P 0.59) with significant variation by occupation (P 0.04). Regarding leak compensation, 241 (46.9%) said NIV ventilators are better, and 146 (284%) said critical care ventilators are better, while 127 (24.7%) said both are similar (P 0.6) without significant variation by occupation (P 0.07). Regarding the general opinion of superiority, 273 (53.1%) said NIV ventilators are better, 131 (25.5%) said critical care ventilators are better, and 110 (21.4%) said both are similar (P 0.42) without significant variation by occupation (P 0.098). Conclusion Despite the lack of evidence, there is wide variability in opinion with no clear consensus regarding the clinicians’ attitude towards which ventilators are superior to use during NIV, especially according to surveyed occupation.

Newborns with congenital diaphragmatic hernia (CDH) can have complex respiratory problems which are worsened by ventilatory induced lung injury. Neurally adjusted ventilator assist (NAVA) is a potentially promising ventilation mode for this population, as it can result in improved patient-ventilator interactions and provision of adequate gas exchange at lower airway pressures. A literature review was undertaken to provide an overview of NAVA and examine its role in the management of infants with CDH. NAVA in neonates has been used in CDH infants who were stable on ventilatory support or being weaned from mechanical ventilation and was associated with a reduction in the level of respiratory support. There is, however, limited evidence regarding the efficacy of NAVA in infants with CDH, with only short-term benefits being investigated. A prospective, multicentre study with long term follow-up is required to appropriately assess NAVA in this population. [ABSTRACT FROM AUTHOR]

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.

BACKGROUND: Pediatric noninvasive ventilation (NIV) is used commonly in the acute care setting and is associated with high incidence of patient ventilator asynchrony. METHODS: An ASL 5000 breathing simulator was used to model pediatric patients with varying patient efforts and lung conditions. For delivery of NIV, a commonly used acute care ventilator was used by connecting a nasal cannula interface to model nares produced with a 3-dimensional printer. The modes of ventilation were NIV pressure control continuous mandatory ventilation and NIV pressure control continuous spontaneous ventilation. Patient and ventilator waveforms were analyzed using the ASL 5000 software to assess for asynchrony events and determine the asynchrony index (AI). RESULTS: Significant asynchrony (AI > 0.1) existed in the majority of scenarios for both pressure control continuous mandatory ventilation and pressure control continuous spontaneous ventilation (79% and 93%, respectively). The most common asynchrony event was ineffective trigger, accounting for 81.9% of events in pressure control continuous mandatory ventilation and 79.3% in pressure control continuous spontaneous ventilation. There were no statistically significant differences in the AI when comparing simulated patient effort or lung condition. CONCLUSIONS: Significant asynchrony exists during NIV with a commonly used acute care ventilator and nasal cannula interface, which raises questions regarding its utility in clinical practice in the pediatric population. [ABSTRACT FROM AUTHOR]

Patient-ventilator dyssynchrony or asynchrony occurs when, for any parameter of respiration, discordance exists between the patient's spontaneous effort and the ventilator's provided support. If not recognised, it may promote oversedation, prolong the duration of mechanical ventilation, create risk for lung injury, and generally confuse the clinical picture. Seven forms of dyssynchrony are common: (a) ineffective triggering; (b) autotriggering; (c) inadequate flow; (d) too much flow; (e) premature cycling; (f) delayed cycling; and (g) peak pressure apnoea. 'Reverse triggering' also occurs and may mimic premature cycling. Correct diagnosis of these phenomena often permits management by simple ventilator optimisation rather than by less desirable measures. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Propofol is increasingly used during partial support mechanical ventilation such as pressure support ventilation (PSV) in postoperative patients. However, breathing pattern, respiratory drive, and patient-ventilator synchrony are affected by the sedative used and the sedation depth. The present study aimed to evaluate the physiologic effects of varying depths of propofol sedation on respiratory drive and patient-ventilator synchrony during PSV in postoperative patients. Methods: Eight postoperative patients receiving PSV for

Introduction: This study was designed to evaluate short-term physiologic outcomes of transitioning neonates with bronchopulmonary dysplasia (BPD) from intensive care unit (ICU) ventilators to both the Trilogy 202 (Philips Healthcare, Andover, MA) and LTV 1200 (CareFusion, Yorba Linda, CA) subacute ventilators. Methods: Six infants with BPD requiring tracheostomies for support with a neonatal-specific ICU ventilator underwent placement of esophageal balloon catheters, airway pressure transducers, flow sensors, oxygen saturation (SpO2), and end tidal carbon dioxide (PETCO2) monitors. Noninvasive gas exchange, airflow, and airway and esophageal pressures (PES) were recorded following 20 min on the ICU ventilator. The infants were placed on the Trilogy 202 and LTV 1200 ventilators in random order at identical settings as the ICU ventilator. We measured noninvasive gas exchange, pressure-rate product (respiratory rate x ΔPES), ventilator response times, and the percentage of spontaneous breaths that triggered the ventilator at 20 min in each subject while being supported with each of the different subacute ventilators. Results: The mean (SD) weight of the six infants was 4.983 (0.56) kg. There were no differences in heart rate (p = 0.51) or SpO2 (p = 0.97) but lower PETCO2, ΔPES, respiratory rate, pressure rate-product, response times, and greater percentage of subject initiated breaths that triggered the ventilator (p < 0.05) was observed with the Trilogy 202 than the LTV 1200. All six infants transitioned successfully from the ICU ventilator to the Trilogy 202 ventilator. Conclusion: In this small group of infants with BPD, the Trilogy 202 ventilator performed better than the LTV 1200. The improved subject efforts, per cent subject triggering, and response times observed with the Trilogy are likely related to differences in triggering algorithms, location of triggering mechanisms, and gas delivery system performance within the ventilators. These pilot data may be useful for informing future clinical study design and understanding differences in the level of support provided by different subacute ventilators in infants with BPD. [ABSTRACT FROM AUTHOR]

Background: Dexmedetomidine can be used for sedation of mechanically ventilated patients and has minor respiratory effects. The aim of this study was to compare the incidence of patient-ventilator dyssynchronies during sedation with dexmedetomidine or propofol.Methods: We conducted a multicentre, prospective, open-label, randomised clinical trial, comparing dexmedetomidine with standard propofol sedation at three intensive care units of university hospitals in Italy. Twenty difficult-to-wean patients for whom the first weaning trial had failed and who were on pressure support ventilation were randomised to receive sedation with either dexmedetomidine or propofol at a similar level of sedation (Richmond Agitation-Sedation Scale [RASS] score +1 to -2). The asynchrony index (AI) was calculated using tracings of airflow, airway pressure and electrical activity of the diaphragm sampled at 0, 0.5, 1, 2, 6, 12, 18 and 24 h.Results: The mean AI was lower with dexmedetomidine than with propofol from 2 h onwards, although the two groups significantly differed only at 12 h (2.68 % vs 9.10 %, p < 0.05). No further difference was observed at 18 and 24 h.Conclusions: When sedation with propofol and dexmedetomidine was compared at similar RASS scores of patients in whom first weaning trial had failed, the AI was lower with dexmedetomidine than with propofol, and this difference was statistically significant at 12 h. These results suggest that sedation with dexmedetomidine may offer some advantages in terms of patient-ventilator synchrony. [ABSTRACT FROM AUTHOR]

Background: Patient-ventilator asynchrony is a major cause of difficult weaning from mechanical ventilation. Neurally adjusted ventilatory assist (NAVA) is reported useful to improve the synchrony in patients with sustained low lung compliance. However, the role of NAVA has not been fully investigated. Case presentation: The patient was a 63-year-old Japanese man with acute respiratory distress syndrome secondary to respiratory infection. He was treated with extracorporeal membrane oxygenation for 7 days and survived. Dynamic compliance at withdrawal of extracorporeal membrane oxygenation decreased to 20 ml/cmH2O or less, but gas exchange was maintained by full support with assist/control mode. However, weaning from mechanical ventilation using a flow trigger failed repeatedly because of patient-ventilator asynchrony with hypercapnic acidosis during partial ventilator support despite using different types of ventilators and different trigger levels. Weaning using NAVA restored the regular respiration and stable and normal acid-base balance. Electromyographic analysis of the diaphragm clearly showed improved triggering of both the start and the end of spontaneous inspiration. Regional ventilation monitoring using electrical impedance tomography showed an increase in tidal volume and a ventilation shift to the dorsal regions during NAVA, indicating that NAVA could deliver gas flow to the dorsal regions to adjust for the magnitude of diaphragmatic excursion. NAVA was applied for 31 days, followed by partial ventilatory support with a conventional flow trigger. The patient was discharged from the intensive care unit on day 110 and has recovered enough to be able to live without a ventilatory support for 5 h per day. Conclusion: Our experience showed that NAVA improved not only patient-ventilator synchrony but also regional ventilation distribution in an acute respiratory distress patient with sustained low lung compliance. [ABSTRACT FROM AUTHOR]

Purpose: 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. Methods: 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), the patient's neural inspiratory time ( T), ventilator pressurization duration ( T), inspiratory time in excess ( T), number of asynchrony events per minute and asynchrony index (AI) were determined. Results: The study included 13 patients, six with COPD, and two with mixed pulmonary disease. T 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 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 and PaCO were not different between ventilatory modes. Conclusion: Compared to PS, NAVA improved patient ventilator synchrony during noninvasive ventilation by reducing T and AI. Moreover, with NAVA, ineffective efforts, and late and premature cyclings were absent. [ABSTRACT FROM AUTHOR]

New neonatal ventilation methods have developed over the recent past and now utilize new technological tools with the aim of decreasing induced lung injury while promoting growth of the developing neonatal lung. The previous methods of patient triggering were based on detecting patient's effort by either air flow or airway pressure differences. This limited the patient control to the initiation of the breath and was plagued by a delay in detecting this initial effort. Recently, neurally adjusted ventilatory assist (NAVA) has emerged as an innovative technology which gives the patient full control of timing and magnitude of the respiratory cycle. The patient-ventilator synchrony is improved because the diaphragmatic electromyogram controls the patient's own breathing as well as the ventilator. In addition to breath initiation; the neural control in NAVA improve synchrony in all phases of mechanical ventilation including breath magnitude, plateau and cycle-off or termination which are all important phases of patient ventilation synchrony. The experience in using NAVA as a tool for neonatal ventilation is still limited, especially in the extremely premature neonate, where little has been published regarding the indications, advantages and limitations of this new technology. NAVA offers other clinical and diagnostic innovations. With NAVA, traditional challenges imposed by airway leaks are easily managed. Additionally, NAVA works in concert with the diaphragm, encouraging its use, and minimizing its atrophy. It can also be a valuable tool in identifying true central apnea. A potential limitation of NAVA use in extremely premature neonates is related to the immaturity of respiratory drive and frequent apnea. Additionally, neonates under heavy sedation or neuromuscular blockade are not good candidates for NAVA. As NAVA is used on more neonatal patients, cumulative knowledge will enhance clinical practice, adding a valuable tool to the armament of neonatal care units. [ABSTRACT FROM AUTHOR]

Purpose: To compare patient-ventilator interaction during PSV and PAV+ in patients that are difficult to wean. Methods: This was a physiologic study involving 11 patients. During three consecutive trials (PSV first trial-PSV1, followed by PAV+, followed by a second PSV trial-PSV2, with the same settings as PSV1) we evaluated mechanical and patient respiratory pattern; inspiratory effort from excursion Pdi (swing), and pressure-time products of the transdiaphragmatic (PTPdi) pressures. Inspiratory (delay) and expiratory (delay) trigger delays, time of synchrony (time), and asynchrony index (AI) were assessed. Results: Compared to PAV+, during PSV trials, the mechanical inspiratory time (Ti) was significantly longer than patient inspiratory time (Ti) ( p < 0.05); Ti showed a prolongation between PSV1 and PAV+, significant comparing PAV+ and PSV2 ( p < 0.05). PAV+ significantly reduced delay ( p < 0.001). The portion of tidal volume (VT) delivered in phase with Ti (VT/VT) was significantly higher during PAV+ ( p < 0.01). The time of synchrony was significantly longer during PAV+ than during PSV ( p < 0.001). During PSV 5 patients out of 11 showed an AI greater than 10%, whereas the AI was nil during PAV+. Conclusion: PAV+ improves patient-ventilator interaction, significantly reducing the incidence of end-expiratory asynchrony and increasing the time of synchrony. [ABSTRACT FROM AUTHOR]

Although non-invasive ventilation is widely used for the management of patients with neuromuscular disease, it remains unclear which ventilatory mode is associated with optimal patient-ventilator interaction and provides more effective gas exchange. The effects of volume-guaranteed pressure support (PSV-VTG) as compared with pressure support ventilation (PSV) and assisted pressure controlled ventilation (APCV) on breathing pattern and patient-ventilator synchrony during sleep, blood gases and subjective comfort were evaluated in a group of stable patients with neuromuscular disease. PSV-VTG, PSV and APCV were applied in random order on three consecutive nights, during which cardio-respiratory monitoring was performed. Arterial blood gases were measured at the end of each ventilatory session. Evaluation of subjective sleep quality, comfort and perception of patient-ventilator synchrony was performed using a 10-item visual analogue questionnaire. Twenty-eight patients were included in the study. The different ventilatory modes showed similar effects on breathing pattern during sleep, arterial blood gases and degree of subjective comfort. Ineffective efforts were only observed during PSV-VTG and were inversely correlated with the variability of leaks ( r = −0.61, P = 0.015). A greater number of prolonged inspirations was observed with PSV-VTG and PSV compared with APCV ( P = 0.048 and 0.029, respectively). There were no correlations between patient comfort and physiological variables or ventilator setting. PSV-VTG did not outperform older modes of ventilation in terms of efficacy on breathing pattern and blood gases. In addition, application of PSV-VTG was associated with a higher rate of patient-ventilator dyssynchrony. Volume-guaranteed pressure support (PSV-VTG) theoretically guarantees minute ventilation more effectively than older modes of non-invasive ventilation. The clinical effects of PSV-VTG were evaluated in patients with neuromuscular disease and chronic hypoventilation. PSV-VTG did not outperform older ventilatory modes in terms of efficacy of gas exchange or comfort, and was associated with more patient-ventilator asynchronies. [ABSTRACT FROM AUTHOR]

Optimizing patient-ventilator synchrony is essential in managing patients who require prolonged mechanical ventilation in the long-term acute-care hospital. Inadequate synchrony can increase work of breathing, cause patient discomfort, and delay both weaning and general rehabilitation. Achieving optimal synchrony in the long-term acute-care hospital depends on a number of factors, including adjusting ventilator settings in response to improving lung function; adjusting psychotropic medications to control delirium, anxiety, and depression; and ensuring there is a well positioned correctly sized tracheostomy tube in the airway. The purpose of this review is to provide an update on issues pertinent to patient-ventilator synchrony in the LTACH setting. [ABSTRACT FROM AUTHOR]

Airway pressure release ventilation (APRV) and bi-level positive airway pressure (BIPAP) are proposed to reduce patient work of breathing (WOB) sufficiently and to obviate issues related to patient-ventilator synchrony, so that spontaneous breathing can be maintained throughout the course of acute lung injury (ALI). Thus, APRV/BIPAP should reduce requirements for sedation and muscle paralysis, and thereby reduce the duration of mechanical ventilation. Only 17 human, animal, or lung-model studies have examined these claims, either directly or indirectly. Most did not target patients with ALI. Studies on sedation use have serious methodological limitations. Other studies found that APRV/BIPAP either increased WOB and asynchrony, or had no effect on energy expenditure. To supplement the discussion of patient WOB during APRV/BIPAP in ALI, 4 clinical examples showed marked elevation and wide variation in patient WOB. One plausible explanation is that spontaneous breathing is superimposed upon the mechanical ventilation pattern. Thus a variety of "breathing environments" exist during APRV/BIPAP that affect patient WOB and respiratory drive differently and perhaps unpredictably. This characteristic of APRV/BIPAP makes WOB comparisons with traditional modes problematic. Furthermore, the theoretical benefits of APRV, in terms of controlling patient WOB, appear particularly limited when lung-protective ventilation is used for ALI patients with high minute ventilation demand. Future research should focus on issues of WOB and synchrony, so that reasonable ventilation protocols can be devised to test clinical outcomes against traditional modes. To date, low-level evidence suggests that promoting spontaneous breathing with APRV/BIPAP may not be appropriate in patients with relatively severe ALI/ARDS. [ABSTRACT FROM AUTHOR]

Patient-ventilator synchrony is a common problem with all patients actively triggering the mechanical ventilator. In many cases synchrony can be improved by vigilant adjustments by the managing clinician. However, in most institutions clinicians are not able to spend the time necessary to ensure synchrony in all patients. Proportional assist ventilation (PAV) and neurally adjusted ventilatory assist (NAVA) were both developed to improve patient-ventilator synchrony by proportionally unloading ventilatory effort and turning control of the ventilatory pattern over to the patient. This paper discusses PAV's and NAVA's theory of operation, general process of application, and the supporting literature. [ABSTRACT FROM AUTHOR]

Assisted (interactive) breathing is generally preferred to controlled breaths in patients on mechanical ventilators. Assisted breaths allow the patient's respiratory muscles to be used, and ventilatory muscle atrophy can be prevented. Moreover, the respiratory drive of the patient does not have to be aggressively blunted. However, interactive breaths need to be synchronized with the patient's efforts during the trigger, the flow delivery, and the cycling phases. Asynchrony during any of these can put an intolerable load on the respiratory muscles, leading to fatigue and the need for a high level of sedation or even paralysis. Current ventilation modes have a number of features that can monitor and enhance synchrony, including adjustment of the trigger variable, the use of pressure-targeted versus fixed-flow-targeted breaths, and manipulations of the cycle variable. Clinicians need to know how to use these ventilation mode and monitor them properly, especially understanding the airway pressure and flow graphics. The clinical challenge is synchronizing ventilator gas delivery with patient effort. [ABSTRACT FROM AUTHOR]

Patient-ventilator synchrony is a complex issue affected by ventilator performance, patient characteristics, and the patient-ventilator interface. The history of patient-ventilator interaction includes avoidance of pharmacalogic paralysis, the development of spontaneous breathing systems, microprocessor technology to maximize interaction, and closed-loop control. While most clinicians agree that patientventilator synchrony is desirable, there remain no cause-and-effect data that asynchrony is associated with poor outcome. [ABSTRACT FROM AUTHOR]

Mechanically, breath design is usually either flow/volume-targeted or pressure-targeted. Both approaches can effectively provide lung-protective ventilation, but they prioritize different ventilation parameters, so their responses to changing respiratory-system mechanics and patient effort are different. These different response behaviors have advantages and disadvantages that can be important in specific circumstances. Flow/volume targeting guarantees a set minute ventilation but sometimes may be difficult to synchronize with patient effort, and it will not limit inspiratory pressure. In contrast, pressure targeting, with its variable flow, may be easier to synchronize and will limit inspiratory pressure, but it provides no control over delivered volume. Skilled clinicians can maximize benefits and minimize problems with either flow/volume targeting or pressure targeting. Indeed, as is often the case in managing complex life-support devices, it is operator expertise rather than the device design features that most impacts patient outcomes. [ABSTRACT FROM AUTHOR]

The article presents a study relative to the comparative evaluation of different helmets on patient-ventilator interaction during noninvasive ventilation. The study aims to asses patient-ventilator synchrony during pressure-support ventilation through three types of helmet with different breathing frequency, time of pressurization and cycling off flow threshold. It was performed at the Respiratory Mechanics Laboratory in the Catholic University in Campobasso, Italy.

Abstract: Purpose: Low tidal volume (V T) delivered by flow-targeted breaths reduces ventilator-induced lung injury but may increase patient breathing effort because of limited flow. We hypothesized that a variable-flow, pressure-targeted breath would improve breathing effort versus a fixed flow–targeted breath. Materials and Methods: We compared pressure assist–control ventilation and volume assist–control ventilation (VACV) in 12 patients with acute respiratory failure receiving 6 to 8 mL/kg V T. Backup frequency, V T, inspiratory time, applied positive end-expiratory pressure and fraction of inspired oxygen were held constant. Patient breathing effort was assessed by airway pressure (Paw) drop below baseline 0.1 second after the breath initiation (P0.1), the maximal Paw drop during the triggering phase (Ptr), the magnitude of ventilator work during flow delivery, and the presence of an active expiratory effort during cycling and air trapping judged by the magnitude of residual flow at end-expiration. Results: Compared with VACV, pressure assist–control ventilation decreased P0.1, Ptr (by 25% and 16%, respectively), and evidence for trapped gas but not ventilator work during flow delivery or cycle dys-synchrony. Peak inspiratory flow was comparable between the 2 modes. Conclusions: In patients receiving small V T VACV with increased breathing effort, variable-flow, pressure-targeted ventilation may provide more comfort by decreasing respiratory drive during the triggering phase. [Copyright &y& Elsevier]

Mechanical ventilation is the second most frequently performed therapeutic intervention after treatment for cardiac arrhythmias in intensive care units today. Countless lives have been saved with its use despite being associated with a greater than 30% in-hospital mortality rate. As life expectancies increase and people with chronic illnesses survive longer, artificial support with mechanical ventilation is also expected to rise. In one survey, over half of senior internal medicine residents reported their training on mechanical ventilation as inadequate, whereas the majority of critical care nurses reported having received no formal education on its use. Technological advances resulting in the availability of sleeker ventilators with graphic waveform displays and new modes of ventilation have challenged the bedside clinicians to incorporate this new data along with evidenced-based research into their daily practice. A review of current thoughts on mechanical ventilation and weaning is presented. [ABSTRACT FROM AUTHOR]

The author reflects on the study by R. Vaschetto and colleagues which compares the effect of various levels of profol sedation on ineffective triggering (IT) while on neurally adjusted ventilatory assistance (NAVA) modes of ventilation or pressure support ventilation (PSV). He says that the sedation level of profol was started and adjusted to keep patients awake. He mentions that NAVA do not permit IT at any level of sedation, but deep sedation will still reduce the respiratory drive.

Patients on mechanical ventilation are likely to suffer stress, which may lead to problems of patient-ventilator synchrony, anxiety, haemodynamic instability and decrease in comfort levels. The aim of this study is to evaluate the effects of preoperative education regarding haemodynamic parameters, patient comfort and anxiety, and patient-ventilator synchrony provided to patients before they undergo cardiac surgery. The study is a randomised, controlled clinical study, it was conducted at the cardiovascular surgery clinic of a teaching hospital in Turkey. The study was conducted on 200 patients who underwent cardiac surgery and received mechanical ventilation. Using the block randomisation method, the patients were grouped into intervention and control groups, with 100 patients in each group. The patients in the intervention group received preoperative education on mechanical ventilation and the usage of the communication panel that patients under mechanical ventilation use to communicate with health personnel, the control group received no education. Data was collected while the patients were on mechanical ventilation support in the intensive care unit on their second postoperative day. The difference between the patient-ventilator synchrony levels of the patients to the mechanical ventilation treatment in the intervention and control groups was found statistically significant (p < 0.05). The differences between the haemodynamic measurements of the patients in both groups, which were measured after the patients woke up and before extubation, were also statistically significant (p < 0.05). Median scores obtained by the patients in the intervention group on the Perianaesthesia Comfort Questionnaire and the Tension-Anxiety subscale of the Profile of Mood Scale were 5.7 and 2.0, respectively. The median scores obtained by the patients in the control group on the same scales were 4.1 and 24.0, respectively. Compared to the participants in the control group, the participants in the intervention group who received education had higher patient-ventilator synchrony, comfort and haemodynamic stability levels, as well as lower anxiety levels when they were under mechanical ventilation, showing that results were better in the intervention group than the control group. [ABSTRACT FROM AUTHOR]