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Respiratory mechanics and lung stress/strain in children with acute respiratory distress syndrome.

ABSTRACT: BACKGROUND:In sedated and paralyzed children with acute respiratory failure, the compliance of respiratory system and functional residual capacity were significantly reduced compared with healthy subjects. However, no major studies in children with ARDS have investigated the role of different levels of PEEP and tidal volume on the partitioned respiratory mechanic (lung and chest wall), stress (transpulmonary pressure) and strain (inflated volume above the functional residual capacity). METHODS:The end-expiratory lung volume was measured using a simplified closed circuit helium dilution method. During an inspiratory and expiratory pause, the airway and esophageal pressure were measured. Transpulmonary pressure was computed as the difference between airway and esophageal pressure. RESULTS:Ten intubated sedated paralyzed healthy children and ten children with ARDS underwent a PEEP trial (4 and 12 cmH2O) with a tidal volume of 8, 10 and 12 ml/kgIBW. The two groups were comparable for age and BMI (2.5 [1.0-5.5] vs 3.0 [1.7-7.2] years and 15.1 ± 2.4 vs 15.3 ± 3.0 kg/m(2)). The functional residual capacity in ARDS patients was significantly lower as compared to the control group (10.4 [9.1-14.3] vs 16.6 [11.7-24.6] ml/kg, p = 0.04). The ARDS patients had a significantly lower respiratory system and lung compliance as compared to control subjects (9.9 ± 5.0 vs 17.8 ± 6.5, 9.3 ± 4.9 vs 16.9 ± 4.1 at 4 cmH2O of PEEP and 11.7 ± 5.8 vs 23.7 ± 6.8, 10.0 ± 4.9 vs 23.4 ± 7.5 at 12 cmH2O of PEEP). The compliance of the chest wall was similar in both groups (76.7 ± 30.2 vs 94.4 ± 76.4 and 92.6 ± 65.3 vs 90.0 ± 61.7 at 4 and 12 cmH2O of PEEP). The lung stress and strain were significantly higher in ARDS patients as compared to control subjects and were poorly related to airway pressure and tidal volume normalized for body weight. CONCLUSIONS:Airway pressures and tidal volume normalized to body weight are poor surrogates for lung stress and strain in mild pediatric ARDS. TRIAL REGISTRATION:Clinialtrials.gov NCT02036801. Registered 13 January 2014.

SUBMITTER: Chiumello D

PROVIDER: S-EPMC4742456 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

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Project description:BackgroundDespite their potential interest for clinical management, measurements of respiratory mechanics in patients with acute respiratory distress syndrome (ARDS) are seldom performed in routine practice. We introduced a systematic assessment of respiratory mechanics in our clinical practice. After the first year of clinical use, we retrospectively assessed whether these measurements had any influence on clinical management and physiological parameters associated with clinical outcomes by comparing their value before and after performing the test.MethodsThe respiratory mechanics assessment constituted a set of bedside measurements to determine passive lung and chest wall mechanics, response to positive end-expiratory pressure, and alveolar derecruitment. It was obtained early after ARDS diagnosis. The results were provided to the clinical team to be used at their own discretion. We compared ventilator settings and physiological variables before and after the test. The physiological endpoints were oxygenation index, dead space, and plateau and driving pressures.ResultsSixty-one consecutive patients with ARDS were enrolled. Esophageal pressure was measured in 53 patients (86.9%). In 41 patients (67.2%), ventilator settings were changed after the measurements, often by reducing positive end-expiratory pressure or by switching pressure-targeted mode to volume-targeted mode. Following changes, the oxygenation index, airway plateau, and driving pressures were significantly improved, whereas the dead-space fraction remained unchanged. The oxygenation index continued to improve in the next 48 h.ConclusionsImplementing a systematic respiratory mechanics test leads to frequent individual adaptations of ventilator settings and allows improvement in oxygenation indexes and reduction of the risk of overdistention at the same time.Trial registrationThe present study involves data from our ongoing registry for respiratory mechanics (ClinicalTrials.gov identifier: NCT02623192 . Registered 30 July 2015).

Project description:ObjectiveGlobal lung stress varies considerably with low tidal volume ventilation for acute respiratory distress syndrome. High stress despite low tidal volumes may worsen lung injury and increase risk of death. No widely available parameter exists to assess global lung stress. We aimed to determine whether the volume delivered during a recruitment maneuver (V(RM)) is inversely associated with lung stress and mortality in acute respiratory distress syndrome.DesignSubstudy of an acute respiratory distress syndrome clinical trial on esophageal pressure-guided positive end-expiratory pressure titration.SettingU.S. academic medical center.PatientsForty-two patients with acute respiratory distress syndrome in whom airflow, airway pressure, and esophageal pressure were recorded during the recruitment maneuver.InterventionsA single recruitment maneuver was performed before initiating protocol-directed ventilator management. Recruitment maneuvers consisted of a 30-second breath hold at 40 cm H2O airway pressure under heavy sedation or paralysis. V(RM) was calculated by integrating the flow-time waveform during the maneuver. End-inspiratory stress was defined as the transpulmonary (airway minus esophageal) pressure during end-inspiratory pause of a tidal breath and tidal stress as the transpulmonary pressure difference between end-inspiratory and end-expiratory pauses.Measurements and main resultsV(RM) ranged between 7.4 and 34.7 mL/kg predicted body weight. Lower V(RM) predicted high end-inspiratory and tidal lung stress (end-inspiratory: β = -0.449; 95% CI, -0.664 to -0.234; p < 0.001; tidal: β = -0.267; 95% CI, -0.423 to -0.111; p = 0.001). After adjusting for PaO2/FIO2 and either driving pressure, tidal volume, or plateau pressure and positive end-expiratory pressure, V(RM) remained independently associated with both end-inspiratory and tidal stress. In unadjusted analysis, low V(RM) predicted increased risk of death (odds ratio, 0.85; 95% CI, 0.72-1.00; p = 0.026). V(RM) remained significantly associated with mortality after adjusting for study arm (odds ratio, 0.84; 95% CI, 0.71-1.00; p = 0.022).ConclusionsLow V(RM) independently predicts high lung stress and may predict risk of death in patients with acute respiratory distress syndrome.

Project description:ImportanceAn increasing number of children survive after acute respiratory distress syndrome (ARDS). The long-term morbidity affecting these survivors, including the burden of hospital readmission and key factors associated with readmission, is unknown.ObjectiveTo determine 1-year readmission rates among survivors of pediatric ARDS and to investigate the associations of 3 key index hospitalization factors (presence or development of a complex chronic condition, receipt of a tracheostomy, and hospital length of stay [LOS]) with readmission.Design, setting, and participantsThis retrospective cohort study used data from the commercial or Medicaid IBM MarketScan databases between 2013 and 2017, with follow-up data through 2018. Participants included hospitalized children (aged ≥28 days to <18 years) who received mechanical ventilation and had algorithm-identified ARDS. Data analysis was completed from March 2022 to March 2023.ExposuresComplex chronic conditions (none, nonrespiratory, and respiratory), receipt of tracheostomy, and index hospital LOS.Main outcomes and measuresThe primary outcome was 1-year, all-cause hospital readmission. Univariable and multivariable Cox proportional hazard models were created to test the association of key hospitalization factors with readmission.ResultsOne-year readmission occurred in 3748 of 13 505 children (median [IQR] age, 4 [0-14] years; 7869 boys [58.3%]) with mechanically ventilated ARDS who survived to hospital discharge. In survival analysis, the probability of 1-year readmission was 30.0% (95% CI, 29.0%-30.8%). One-half of readmissions occurred within 61 days of discharge (95% CI, 56-67 days). Both respiratory (adjusted hazard ratio [aHR], 2.69; 95% CI, 2.42-2.98) and nonrespiratory (aHR, 1.86; 95% CI, 1.71-2.03) complex chronic conditions were associated with 1-year readmission. Placement of a new tracheostomy (aHR, 1.98; 95% CI, 1.69-2.33) and LOS 14 days or longer (aHR, 1.87; 95% CI, 1.62-2.16) were associated with readmission. After exclusion of children with chronic conditions, LOS 14 days or longer continued to be associated with readmission (aHR, 1.92; 95% CI, 1.49-2.47).Conclusions and relevanceIn this retrospective cohort study of children with ARDS who survived to discharge, important factors associated with readmission included the presence or development of chronic medical conditions during the index admission, tracheostomy placement during index admission, and index hospitalization of 14 days or longer. Future studies should evaluate whether postdischarge interventions (eg, telephonic contact, follow-up clinics, and home health care) may help reduce the readmission burden.

Project description:ObjectivesPediatric acute respiratory distress syndrome is heterogeneous, with a paucity of risk stratification tools to assist with trial design. We aimed to develop and validate mortality prediction models for patients with pediatric acute respiratory distress syndrome.DesignLeveraging additional data collection from a preplanned ancillary study (Version 1) of the multinational Pediatric Acute Respiratory Distress syndrome Incidence and Epidemiology study, we identified predictors of mortality. Separate models were built for the entire Version 1 cohort, for the cohort excluding neurologic deaths, for intubated subjects, and for intubated subjects excluding neurologic deaths. Models were externally validated in a cohort of intubated pediatric acute respiratory distress syndrome patients from the Children's Hospital of Philadelphia.SettingThe derivation cohort represented 100 centers worldwide; the validation cohort was from Children's Hospital of Philadelphia.PatientsThere were 624 and 640 subjects in the derivation and validation cohorts, respectively.InterventionsNone.Measurements and main resultsThe model for the full cohort included immunocompromised status, Pediatric Logistic Organ Dysfunction 2 score, day 0 vasopressor-inotrope score and fluid balance, and PaO2/FIO2 6 hours after pediatric acute respiratory distress syndrome onset. This model had good discrimination (area under the receiver operating characteristic curve 0.82), calibration, and internal validation. Models excluding neurologic deaths, for intubated subjects, and for intubated subjects excluding neurologic deaths also demonstrated good discrimination (all area under the receiver operating characteristic curve ≥ 0.84) and calibration. In the validation cohort, models for intubated pediatric acute respiratory distress syndrome (including and excluding neurologic deaths) had excellent discrimination (both area under the receiver operating characteristic curve ≥ 0.85), but poor calibration. After revision, the model for all intubated subjects remained miscalibrated, whereas the model excluding neurologic deaths showed perfect calibration. Mortality models also stratified ventilator-free days at 28 days in both derivation and validation cohorts.ConclusionsWe describe predictive models for mortality in pediatric acute respiratory distress syndrome using readily available variables from day 0 of pediatric acute respiratory distress syndrome which outperform severity of illness scores and which demonstrate utility for composite outcomes such as ventilator-free days. Models can assist with risk stratification for clinical trials.

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Respiratory mechanics and lung stress/strain in children with acute respiratory distress syndrome.

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