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Automated control of mechanical ventilation during general anaesthesia: study protocol of a bicentric observational study (AVAS).

ABSTRACT: Automated control of mechanical ventilation during general anaesthesia is not common. A novel system for automated control of most of the ventilator settings was designed and is available on an anaesthesia machine.The 'Automated control of mechanical ventilation during general anesthesia study' (AVAS) is an international investigator-initiated bicentric observational study designed to examine safety and efficacy of the system during general anaesthesia. The system controls mechanical breathing frequency, inspiratory pressure, pressure support, inspiratory time and trigger sensitivity with the aim to keep a patient stable in user adoptable target zones. Adult patients, who are classified as American Society of Anesthesiologists physical status I, II or III, scheduled for elective surgery of the upper or lower limb or for peripheral vascular surgery in general anaesthesia without any additional regional anaesthesia technique and who gave written consent for study participation are eligible for study inclusion. Primary endpoint of the study is the frequency of specifically defined adverse events. Secondary endpoints are frequency of normoventilation, hypoventilation and hyperventilation, the time period between switch from controlled ventilation to assisted ventilation, achievement of stable assisted ventilation of the patient, proportion of time within the target zone for tidal volume, end-tidal partial pressure of carbon dioxide as individually set up for each patient by the user, frequency of alarms, frequency distribution of tidal volume, inspiratory pressure, inspiration time, expiration time, end-tidal partial pressure of carbon dioxide and the number of re-intubations.AVAS will be the first clinical study investigating a novel automated system for the control of mechanical ventilation on an anaesthesia machine. The study was approved by the ethics committees of both participating study sites. In case that safety and efficacy are acceptable, a randomised controlled trial comparing the novel system with the usual practice may be warranted.DRKS DRKS00011025, registered 12 October 2016; clinicaltrials.gov ID. NCT02644005, registered 30 December 2015.

SUBMITTER: Schadler D

PROVIDER: S-EPMC5566603 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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Automated control of mechanical ventilation during general anaesthesia: study protocol of a bicentric observational study (AVAS).

Schädler Dirk D Miestinger Georg G Becher Tobias T Frerichs Inéz I Weiler Norbert N Hörmann Christoph C

BMJ open 20170510 5

<h4>Introduction</h4>Automated control of mechanical ventilation during general anaesthesia is not common. A novel system for automated control of most of the ventilator settings was designed and is available on an anaesthesia machine.<h4>Methods and analysis</h4>The 'Automated control of mechanical ventilation during general anesthesia study' (AVAS) is an international investigator-initiated bicentric observational study designed to examine safety and efficacy of the system during general anaes ...[more]

PMID: 28495814

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Project description:BACKGROUND:Adaptive mechanical ventilation automatically adjusts respiratory rate (RR) and tidal volume (VT) to deliver the clinically desired minute ventilation, selecting RR and VT based on Otis' equation on least work of breathing. However, the resulting VT may be relatively high, especially in patients with more compliant lungs. Therefore, a new mode of adaptive ventilation (adaptive ventilation mode 2, AVM2) was developed which automatically minimizes inspiratory power with the aim of ensuring lung-protective combinations of VT and RR. The aim of this study was to investigate whether AVM2 reduces VT, mechanical power, and driving pressure (?Pstat) and provides similar gas exchange when compared to adaptive mechanical ventilation based on Otis' equation. METHODS:A prospective randomized cross-over study was performed in 20 critically ill patients on controlled mechanical ventilation, including 10 patients with acute respiratory distress syndrome (ARDS). Each patient underwent 1 h of mechanical ventilation with AVM2 and 1 h of adaptive mechanical ventilation according to Otis' equation (adaptive ventilation mode, AVM). At the end of each phase, we collected data on VT, mechanical power, ?P, PaO2/FiO2 ratio, PaCO2, pH, and hemodynamics. RESULTS:Comparing adaptive mechanical ventilation with AVM2 to the approach based on Otis' equation (AVM), we found a significant reduction in VT both in the whole study population (7.2?±?0.9 vs. 8.2?±?0.6?ml/kg, p?<? 0.0001) and in the subgroup of patients with ARDS (6.6?±?0.8?ml/kg with AVM2 vs. 7.9?±?0.5?ml/kg with AVM, p?<? 0.0001). Similar reductions were observed for ?Pstat (whole study population: 11.5?±?1.6 cmH2O with AVM2 vs. 12.6?±?2.5 cmH2O with AVM, p?<? 0.0001; patients with ARDS: 11.8?±?1.7 cmH2O with AVM2 and 13.3?±?2.7 cmH2O with AVM, p?=?0.0044) and total mechanical power (16.8?±?3.9?J/min with AVM2 vs. 18.6?±?4.6?J/min with AVM, p?=?0.0024; ARDS: 15.6?±?3.2?J/min with AVM2 vs. 17.5?±?4.1?J/min with AVM, p?=?0.0023). There was a small decrease in PaO2/FiO2 (270?±?98 vs. 291?±?102?mmHg with AVM, p?=?0.03; ARDS: 194?±?55 vs. 218?±?61 with AVM, p?=?0.008) and no differences in PaCO2, pH, and hemodynamics. CONCLUSIONS:Adaptive mechanical ventilation with automated minimization of inspiratory power may lead to more lung-protective ventilator settings when compared with adaptive mechanical ventilation according to Otis' equation. TRIAL REGISTRATION:The study was registered at the German Clinical Trials Register ( DRKS00013540 ) on December 1, 2017, before including the first patient.

Project description:BackgroundCytomegalovirus (CMV) reactivation is associated with adverse prognoses of critically ill patients. However, the epidemiology and predictors of CMV reactivation in immunocompetent patients receiving mechanical ventilation (MV) are not clear. The aim of this study was to investigate the epidemiology and predictors of CMV reactivation in immunocompetent patients requiring MV.MethodsA single-center, prospective observational study (conducted from June 30, 2017 to July 01, 2018) with a follow-up of 90 days (September 29, 2018) that included 71 CMV-seropositive immunocompetent patients with MV at a 37-bed university hospital general intensive care unit (ICU) in China. Routine detection of CMV DNAemia was performed once a week for 28 days (Days 1, 7, 14, 21, and 28). CMV serology, laboratory findings, and clinical data were obtained during hospitalization.ResultsAmong 71 patients, 13 (18.3%) showed CMV reactivation within 28 days in the ICU. The median time to reactivation was 7 days. CMV reactivation was related to various factors, including body mass index (BMI), sepsis, N-terminal pro-b-type natriuretic peptide (NT-proBNP), blood urea nitrogen (BUN), and hemoglobin (Hb) levels (P < 0.05). In the multivariate regression model, BMI, Hb level, and sepsis were independently associated with CMV reactivation patients (P < 0.05). Moreover, the area under the receiver operating characteristic (AUROC) of BMI, Hb, and BMI combined with Hb was 0.69, 0.70, and 0.76, respectively. The duration of MV, hospitalization expense, length of ICU stay, and 90 day all-cause mortality rate in patients with CMV reactivation was significantly higher than in those without CMV reactivation (P < 0.05).ConclusionsAmong immunocompetent patients with MV, the incidence of CMV reactivation was 18.3%. CMV reactivation was associated with several adverse prognoses. BMI, Hb, and sepsis were independent risk factors for CMV reactivation. BMI and Hb may predict CMV reactivation.

Project description:BackgroundHost-associated microbial communities have important roles in tissue homeostasis and overall health. Severe perturbations can occur within these microbial communities during critical illness due to underlying diseases and clinical interventions, potentially influencing patient outcomes. We sought to profile the microbial composition of critically ill mechanically ventilated patients, and to determine whether microbial diversity is associated with illness severity and mortality.MethodsWe conducted a prospective, observational study of mechanically ventilated critically ill patients with a high incidence of pneumonia in 2 intensive care units (ICUs) in Hamilton, Canada, nested within a randomized trial for the prevention of healthcare-associated infections. The microbial profiles of specimens from 3 anatomical sites (respiratory, and upper and lower gastrointestinal tracts) were characterized using 16S ribosomal RNA gene sequencing.ResultsWe collected 65 specimens from 34 ICU patients enrolled in the trial (29 endotracheal aspirates, 26 gastric aspirates and 10 stool specimens). Specimens were collected at a median time of 3 days (lower respiratory tract and gastric aspirates; interquartile range [IQR] 2-4) and 6 days (stool; IQR 4.25-6.75) following ICU admission. We observed a loss of biogeographical distinction between the lower respiratory tract and gastrointestinal tract microbiota during critical illness. Moreover, microbial diversity in the respiratory tract was inversely correlated with APACHE II score (r = - 0.46, p = 0.013) and was associated with hospital mortality (Median Shannon index: Discharged alive; 1.964 vs. Deceased; 1.348, p = 0.045).ConclusionsThe composition of the host-associated microbial communities is severely perturbed during critical illness. Reduced microbial diversity reflects high illness severity and is associated with mortality. Microbial diversity may be a biomarker of prognostic value in mechanically ventilated patients.Trial registrationClinicalTrials.gov ID NCT01782755 . Registered February 4 2013.

Project description:IntroductionResearch supports the use of specific strategies to discontinue mechanical ventilation (MV) in critically ill patients. Little is known about how clinicians actually wean and discontinue MV in practice or the association between different discontinuation strategies and outcomes. The primary objective of this study is to describe international practices in the use of (1) daily screening for readiness to discontinue MV, (2) modes of MV used before initial discontinuation attempts, (3) weaning and spontaneous breathing trial (SBT) protocols, (4) SBT techniques and (5) sedation and mobilisation practices to facilitate weaning and discontinuation. The secondary objectives are to identify patient characteristics and time-dependent factors associated with use of selected strategies, investigate associations between SBT outcome (failure vs success) and outcomes, explore differences between patients who undergo an SBT early versus later in their intensive care unit (ICU) stay, and investigate the associations between different SBT techniques and humidification strategies on outcomes.Methods and analysisWe will conduct an international, prospective, observational study of MV discontinuation practices among critically ill adults who receive invasive MV for at least 24 hours at approximately 150 ICUs in six geographic regions (Canada, USA, UK, Europe, India and Australia/New Zealand). Research personnel at participating ICUs will collect demographic data, data to characterise the initial strategy or event that facilitated discontinuation of MV (direct extubation, direct tracheostomy, initial successful SBT, initial failed SBT or death before any attempt could be made), clinical outcomes and site information. We aim to collect data on at least 10 non-death discontinuation events in each ICU (at least 1500 non-death discontinuation events).Ethics and disseminationThis study received Research Ethics Approval from St. Michael's Hospital (11-024) Research ethics approval will be sought from all participating sites. The results will be disseminated through publications in peer-reviewed journals.Trial registration numberNCT03955874.

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Automated control of mechanical ventilation during general anaesthesia: study protocol of a bicentric observational study (AVAS).

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Automated control of mechanical ventilation during general anaesthesia: study protocol of a bicentric observational study (AVAS).

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