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Assessment of spontaneous breathing during pressure controlled ventilation with superimposed spontaneous breathing using respiratory flow signal analysis.

ABSTRACT: Integrating spontaneous breathing into mechanical ventilation (MV) can speed up liberation from it and reduce its invasiveness. On the other hand, inadequate and asynchronous spontaneous breathing has the potential to aggravate lung injury. During use of airway-pressure-release-ventilation (APRV), the assisted breaths are difficult to measure. We developed an algorithm to differentiate the breaths in a setting of lung injury in spontaneously breathing ewes. We hypothesized that differentiation of breaths into spontaneous, mechanical and assisted is feasible using a specially developed for this purpose algorithm. Ventilation parameters were recorded by software that integrated ventilator output variables. The flow signal, measured by the EVITA® XL (Lübeck, Germany), was measured every 2 ms by a custom Java-based computerized algorithm (Breath-Sep). By integrating the flow signal, tidal volume (V_T) of each breath was calculated. By using the flow curve the algorithm separated the different breaths and numbered them for each time point. Breaths were separated into mechanical, assisted and spontaneous. Bland Altman analysis was used to compare parameters. Comparing the values calculated by Breath-Sep with the data from the EVITA® using Bland-Altman analyses showed a mean bias of - 2.85% and 95% limits of agreement from - 25.76 to 20.06% for MV_total. For respiratory rate (RR) RR_set a bias of 0.84% with a SD of 1.21% and 95% limits of agreement from - 1.53 to 3.21% were found. In the cluster analysis of the 25th highest breaths of each group RR_total was higher using the EVITA®. In the mechanical subgroup the values for RR_spont and MV_spont the EVITA® showed higher values compared to Breath-Sep. We developed a computerized method for respiratory flow-curve based differentiation of breathing cycle components during mechanical ventilation with superimposed spontaneous breathing. Further studies in humans and optimizing of this technique is necessary to allow for real-time use at the bedside.

SUBMITTER: Kreyer S

PROVIDER: S-EPMC7293172 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundRecent guidelines recommended conducting spontaneous breathing trial (SBT) with modest inspiratory pressure augmentation rather than T-piece or continuous positive airway pressure. However, it was based on few studies focused on the outcomes of extubation rather than the weaning process, despite the existence of various weaning situations in clinical practice. This study was designed to investigate the effects of SBT with pressure support ventilation (PSV) or T-piece on weaning outcomes.MethodsAll consecutive patients admitted to two medical intensive care units (ICUs) and those requiring mechanical ventilation (MV) for more than 24 h from November 1, 2017 to September 30, 2020 were prospectively registered. T-piece trial was used until March 2019, and then, pressure support of 8 cmH2O and 0 positive end-expiratory pressure were used for SBT since July 2019, after a 3-month transition period for the revised SBT protocol. The primary outcome of this study was successful weaning defined according to the WIND (Weaning according to a New Definition) definition and were compared between the T-piece group and PSV group. The association between the SBT method and weaning outcome was evaluated with logistic regression analysis.ResultsIn this study, 787 eligible patients were divided into the T-piece (n = 473) and PSV (n = 314) groups after excluding patients for a 3-month transition period. Successful weaning was not different between the two groups (85.0% vs. 86.3%; p = 0.607). However, the PSV group had a higher proportion of short weaning (70.1% vs. 59.0%; p = 0.002) and lower proportion of difficult weaning (13.1% vs. 24.1%; p < 0.001) than the T-piece group. The proportion of prolonged weaning was similar between the two groups (16.9% vs. 16.9%; p = 0.990). After excluding patients who underwent tracheostomy before the SBTs, similar results were found. Reintubation rates at 48 h, 72 h, and 7 days following the planned extubation were not different between the PSV and T-piece groups. Moreover, no significant differences in intensive care unit and hospital mortality and length of stay were observed.ConclusionsIn critically ill medical patients, SBT using PSV was not associated with a higher rate of successful weaning compared with SBT using T-piece. However, PSV could shorten the weaning process without increasing the risk of reintubation.

Project description:BackgroundA continuous gas flow provided by flow-controlled ventilation (FCV) facilitates accurate dynamic compliance measurement and allows the clinician to individually optimise positive end-expiratory and peak pressure settings accordingly.ObjectiveThe aim of this study was to compare the efficiency of gas exchange and impact on haemodynamics between individualised FCV and pressure-controlled ventilation (PCV) in a porcine model of oleic acid-induced acute respiratory distress syndrome (ARDS).DesignRandomised controlled interventional trial conducted on 16 pigs.SettingAnimal operating facility at the Medical University Innsbruck.InterventionsARDS was induced in lung healthy pigs by intravenous infusion of oleic acid until moderate-to-severe ARDS at a stable Horowitz quotient (PaO 2 FiO 2-1 ) of 80 to 120 over a period of 30 min was obtained. Ventilation was then either performed with individualised FCV ( n = 8) established by compliance-guided pressure titration or PCV ( n = 8) with compliance-guided titration of the positive end-expiratory pressure and peak pressure set to achieve a tidal volume of 6 ml kg -1 over a period of 2 h.Main outcome measuresGas exchange parameters were assessed by the PaO 2 FiO 2-1 quotient and CO 2 removal by the PaCO 2 value in relation to required respiratory minute volume. Required catecholamine support for haemodynamic stabilisation was measured.ResultsThe FCV group showed significantly improved oxygenation [149.2 vs. 110.4, median difference (MD) 38.7 (8.0 to 69.5) PaO 2 FiO 2-1 ; P = 0.027] and CO 2 removal [PaCO 2 7.25 vs. 9.05, MD -1.8 (-2.87 to -0.72) kPa; P = 0.006] at a significantly lower respiratory minute volume [8.4 vs. 11.9, MD -3.6 (-5.6 to -1.5) l min -1 ; P = 0.005] compared with PCV. In addition, in FCV-pigs, haemodynamic stabilisation occurred with a significant reduction of required catecholamine support [norepinephrine 0.26 vs. 0.86, MD -0.61 (-1.12 to -0.09) μg kg -1 min -1 ; P = 0.037] during 2 ventilation hours.ConclusionIn this oleic acid-induced porcine ARDS model, individualised FCV significantly improved gas exchange and haemodynamic stability compared with PCV.Trial registrationProtocol no.: BMBWF-66.011/0105-V/3b/2019).

Project description:BackgroundA spontaneous breathing trial (SBT) is used to determine whether patients are ready for extubation, but the best method for choosing the SBT strategy remains controversial. We investigated the effect of high-flow oxygen versus T-piece ventilation strategies during SBT on rates of weaning failure among patients receiving mechanical ventilation.MethodsThis randomized clinical trial was conducted from June 2019 through January 2022 among patients receiving mechanical ventilation for ≥ 12 h who fulfilled the weaning readiness criteria at a single-center medical intensive care unit. Patients were randomized to undergo either T-piece SBT or high-flow oxygen SBT. The primary outcome was weaning failure on day 2, and the secondary outcomes were weaning failure on day 7, ICU and hospital length of stay, and ICU and in-hospital morality.ResultsOf 108 patients (mean age, 67.0 ± 11.1 years; 64.8% men), 54 received T-piece SBT and 54 received high-flow oxygen SBT. Weaning failure on day 2 occurred in 5 patients (9.3%) in the T-piece group and 3 patients (5.6%) in the high-flow group (difference, 3.7% [95% CI, - 6.1-13.6]; p = 0.713). Weaning failure on day 7 occurred in 13 patients (24.1%) in the T-piece group and 7 patients (13.0%) in the high-flow group (difference, 11.1% [95% CI, - 3.4-25.6]; p = 0.215). A post hoc subgroup analysis showed that high-flow oxygen SBT was significantly associated with a lower rate of weaning failure on day 7 (OR, 0.17 [95% CI, 0.04-0.78]) among those patients intubated because of respiratory failure (p for interaction = 0.020). The ICU and hospital length of stay and mortality rates did not differ significantly between the two groups. During the study, no serious adverse events were recorded.ConclusionsAmong patients receiving mechanical ventilation, high-flow oxygen SBT did not significantly reduce the risk of weaning failure compared with T-piece SBT. However, the study may have been underpowered to detect a clinically important treatment effect for the comparison of high-flow oxygen SBT versus T-piece SBT, and a higher percentage of patients with simple weaning and a lower weaning failure rate than expected should be considered when interpreting the findings. Clinical trial registration This trial was registered with ClinicalTrials.gov (number NCT03929328) on April 26, 2019.

Project description:ImportanceDaily spontaneous breathing trials (SBTs) are the best approach to determine whether patients are ready for disconnection from mechanical ventilation, but mode and duration of SBT remain controversial.ObjectiveTo evaluate the effect of an SBT consisting of 30 minutes of pressure support ventilation (an approach that is less demanding for patients) vs an SBT consisting of 2 hours of T-piece ventilation (an approach that is more demanding for patients) on rates of successful extubation.Design, setting, and participantsRandomized clinical trial conducted from January 2016 to April 2017 among 1153 adults deemed ready for weaning after at least 24 hours of mechanical ventilation at 18 intensive care units in Spain. Follow-up ended in July 2017.InterventionsPatients were randomized to undergo a 2-hour T-piece SBT (n = 578) or a 30-minute SBT with 8-cm H2O pressure support ventilation (n = 557).Main outcome and measuresThe primary outcome was successful extubation (remaining free of mechanical ventilation 72 hours after first SBT). Secondary outcomes were reintubation among patients extubated after SBT; intensive care unit and hospital lengths of stay; and hospital and 90-day mortality.ResultsAmong 1153 patients who were randomized (mean age, 62.2 [SD, 15.7] years; 428 [37.1%] women), 1018 (88.3%) completed the trial. Successful extubation occurred in 473 patients (82.3%) in the pressure support ventilation group and 428 patients (74.0%) in the T-piece group (difference, 8.2%; 95% CI, 3.4%-13.0%; P = .001). Among secondary outcomes, for the pressure support ventilation group vs the T-piece group, respectively, reintubation was 11.1% vs 11.9% (difference, -0.8%; 95% CI, -4.8% to 3.1%; P = .63), median intensive care unit length of stay was 9 days vs 10 days (mean difference, -0.3 days; 95% CI, -1.7 to 1.1 days; P = .69), median hospital length of stay was 24 days vs 24 days (mean difference, 1.3 days; 95% CI, -2.2 to 4.9 days; P = .45), hospital mortality was 10.4% vs 14.9% (difference, -4.4%; 95% CI, -8.3% to -0.6%; P = .02), and 90-day mortality was 13.2% vs 17.3% (difference, -4.1% [95% CI, -8.2% to 0.01%; P = .04]; hazard ratio, 0.74 [95% CI, 0.55-0.99]).Conclusions and relevanceAmong patients receiving mechanical ventilation, a spontaneous breathing trial consisting of 30 minutes of pressure support ventilation, compared with 2 hours of T-piece ventilation, led to significantly higher rates of successful extubation. These findings support the use of a shorter, less demanding ventilation strategy for spontaneous breathing trials.Trial registrationClinicalTrials.gov Identifier: NCT02620358.

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Assessment of spontaneous breathing during pressure controlled ventilation with superimposed spontaneous breathing using respiratory flow signal analysis.

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