Rosa Lidia Fernández

Pediatric Acute Lung Injury Epidemiology and Natural History Study: Incidence and outcome of the acute respiratory distress syndrome in children*

Objectives:The incidence and outcome of the acute respiratory distress syndrome in children are not well-known, especially under current ventilatory practices. The goal of this study was to determine the incidence, etiology, and outcome of acute respiratory distress syndrome in the pediatric population in the setting of lung protective ventilation. Design:A 1-yr, prospective, multicenter, observational study in 12 geographical areas of Spain (serving a population of 3.77 million ⩽15 yrs of age) covered by 21 pediatric intensive care units. Subjects:All consecutive pediatric patients receiving invasive mechanical ventilation and meeting American-European Consensus Criteria for acute respiratory distress syndrome. Interventions:None. Measurements and Main Results:Data on ventilatory management, gas exchange, hemodynamics, and organ dysfunction were collected. A total of 146 mechanically ventilated patients fulfilled the acute respiratory distress syndrome definition, representing a incidence of 3.9/100,000 population ⩽15 yrs of age/yr. Pneumonia and sepsis were the most common causes of acute respiratory distress syndrome. At the time of meeting acute respiratory distress syndrome criteria, mean PaO2/FIO2 was 99 mm Hg ± 41 mm Hg, mean tidal volume was 7.6 mL/kg ± 1.8 mL/kg predicted body weight, mean plateau pressure was 27 cm H2O ± 6 cm H2O, and mean positive end-expiratory pressure was 8.9 cm ± 2.9 cm H2O. Overall pediatric intensive care unit and hospital mortality were 26% (95% confidence interval 19.6–33.7) and 27.4% (95% confidence interval 20.8–35.1), respectively. At 24 hrs, after the assessment of oxygenation under standard ventilatory settings, 118 (80.8%) patients continued to meet acute respiratory distress syndrome criteria (PaO2/FIO2 104 mm Hg ± 36 mm Hg; pediatric intensive care units mortality 30.5%), whereas 28 patients (19.2%) had a PaO2/FIO2 >200 mm Hg (pediatric intensive care units mortality 7.1%) (p = .014). Conclusions:This is the largest study to estimate prospectively the pediatric population-based acute respiratory distress syndrome incidence and the first incidence study performed during the routine application of lung protective ventilation in children. Our findings support a lower acute respiratory distress syndrome incidence and mortality than those reported for adults. PaO2/FIO2 ratios at acute respiratory distress syndrome onset and at 24 hrs after onset were helpful in defining groups at greater risk of dying (clinical trials registered with http://www.clinicaltrials.gov; NCT 01142544)

A Clinical Classification of the Acute Respiratory Distress Syndrome for Predicting Outcome and Guiding Medical Therapy

Objective:Current in-hospital mortality of the acute respiratory distress syndrome (ARDS) is above 40%. ARDS outcome depends on the lung injury severity within the first 24 hours of ARDS onset. We investigated whether two widely accepted cutoff values of PaO2/FIO2 and positive end-expiratory pressure (PEEP) would identify subsets of patients with ARDS for predicting outcome and guiding therapy. Design:A 16-month (September 2008 to January 2010) prospective, multicenter, observational study. Setting:Seventeen multidisciplinary ICUs in Spain. Patients:We studied 300 consecutive, mechanically ventilated patients meeting American-European Consensus Conference criteria for ARDS (PaO2/FIO2 ⩽ 200 mm Hg) on PEEP greater than or equal to 5 cm H2O, and followed up until hospital discharge. Interventions:None. Measurements and Main Results:Based on threshold values for PaO2/FIO2 (150 mm Hg) and PEEP (10 cm H2O) at ARDS onset and at 24 hours, we assigned patients to four categories: group I (PaO2/FIO2 ≥ 150 on PEEP < 10), group II (PaO2/FIO2 ≥ 150 on PEEP ≥ 10), group III (PaO2/FIO2 < 150 on PEEP < 10), and group IV (PaO2/FIO2 < 150 on PEEP ≥ 10). The primary outcome was all-cause in-hospital mortality. Overall hospital mortality was 46.3%. Although at study entry, patients with PaO2/FIO2 less than 150 had a higher mortality than patients with a PaO2/FIO2 greater than or equal to 150 (p = 0.044), there was minimal variability in mortality among the four groups (p = 0.186). However, classification of patients in each group changed markedly after 24 hours of usual care. Group categorization at 24 hours provided a strong association with in-hospital mortality (p < 0.00001): group I had the lowest mortality (23.1%), whereas group IV had the highest mortality (60.3%). Conclusions:The degree of lung dysfunction established by a PaO2/FIO2 of 150 mm Hg and a PEEP of 10 cm H2O demonstrated that ARDS is not a homogeneous disorder. Rather, it is a series of four subsets that should be considered for enrollment in clinical trials and for guiding therapy. A major contribution of our study is the distinction between survival after 24 hours of care versus survival at the time of ARDS onset.

Assessment of PaO2/FiO2 for stratification of patients with moderate and severe acute respiratory distress syndrome

Objectives A recent update of the definition of acute respiratory distress syndrome (ARDS) proposed an empirical classification based on ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) at ARDS onset. Since the proposal did not mandate PaO2/FiO2 calculation under standardised ventilator settings (SVS), we hypothesised that a stratification based on baseline PaO2/FiO2 would not provide accurate assessment of lung injury severity. Design A prospective, multicentre, observational study. Setting A network of teaching hospitals. Participants 478 patients with eligible criteria for moderate (100<PaO2/FiO2≤200) and severe (PaO2/FiO2≤100) ARDS and followed until hospital discharge. Interventions We examined physiological and ventilator parameters in association with the PaO2/FiO2 at ARDS onset, after 24 h of usual care and at 24 h under a SVS. At 24 h, patients were reclassified as severe, moderate, mild (200<PaO2/FiO2≤300) ARDS and non-ARDS (PaO2/FiO2>300). Primary and secondary outcomes Group severity and hospital mortality. Results At ARDS onset, 173 patients had a PaO2/FiO2≤100 but only 38.7% met criteria for severe ARDS at 24 h under SVS. When assessed under SVS, 61.3% of patients with severe ARDS were reclassified as moderate, mild and non-ARDS, while lung severity and hospital mortality changed markedly with every PaO2/FiO2 category (p<0.000001). Our model of risk stratification outperformed the stratification using baseline PaO2/FiO2 and non-standardised PaO2/FiO2 at 24 h, when analysed by the predictive receiver operating characteristic (ROC) curve: area under the ROC curve for stratification at baseline was 0.583 (95% CI 0.525 to 0.636), 0.605 (95% CI 0.552 to 0.658) at 24 h without SVS and 0.693 (95% CI 0.645 to 0.742) at 24 h under SVS (p<0.000001). Conclusions Our findings support the need for patient assessment under SVS at 24 h after ARDS onset to assess disease severity, and have implications for the diagnosis and management of ARDS patients. Trial registration numbers NCT00435110 and NCT00736892.

Age, PaO2/FIO2, and Plateau Pressure Score: A Proposal for a Simple Outcome Score in Patients With the Acute Respiratory Distress Syndrome.

Objectives: Although there is general agreement on the characteristic features of the acute respiratory distress syndrome, we lack a scoring system that predicts acute respiratory distress syndrome outcome with high probability. Our objective was to develop an outcome score that clinicians could easily calculate at the bedside to predict the risk of death of acute respiratory distress syndrome patients 24 hours after diagnosis. Design: A prospective, multicenter, observational, descriptive, and validation study. Setting: A network of multidisciplinary ICUs. Patients: Six-hundred patients meeting Berlin criteria for moderate and severe acute respiratory distress syndrome enrolled in two independent cohorts treated with lung-protective ventilation. Interventions: None. Measurements and Main Results: Using individual demographic, pulmonary, and systemic data at 24 hours after acute respiratory distress syndrome diagnosis, we derived our prediction score in 300 acute respiratory distress syndrome patients based on stratification of variable values into tertiles, and validated in an independent cohort of 300 acute respiratory distress syndrome patients. Primary outcome was in-hospital mortality. We found that a 9-point score based on patient’s age, PaO2/FIO2 ratio, and plateau pressure at 24 hours after acute respiratory distress syndrome diagnosis was associated with death. Patients with a score greater than 7 had a mortality of 83.3% (relative risk, 5.7; 95% CI, 3.0–11.0), whereas patients with scores less than 5 had a mortality of 14.5% (p < 0.0000001). We confirmed the predictive validity of the score in a validation cohort. Conclusions: A simple 9-point score based on the values of age, PaO2/FIO2 ratio, and plateau pressure calculated at 24 hours on protective ventilation after acute respiratory distress syndrome diagnosis could be used in real time for rating prognosis of acute respiratory distress syndrome patients with high probability.

A Quantile Analysis of Plateau and Driving Pressures: Effects on Mortality in Patients With Acute Respiratory Distress Syndrome Receiving Lung-protective Ventilation.

Objectives: The driving pressure (plateau pressure minus positive end-expiratory pressure) has been suggested as the major determinant for the beneficial effects of lung-protective ventilation. We tested whether driving pressure was superior to the variables that define it in predicting outcome in patients with acute respiratory distress syndrome. Design: A secondary analysis of existing data from previously reported observational studies. Setting: A network of ICUs. Patients: We studied 778 patients with moderate to severe acute respiratory distress syndrome. Interventions: None. Measurements and Main Results: We assessed the risk of hospital death based on quantiles of tidal volume, positive end-expiratory pressure, plateau pressure, and driving pressure evaluated at 24 hours after acute respiratory distress syndrome diagnosis while ventilated with standardized lung-protective ventilation. We derived our model using individual data from 478 acute respiratory distress syndrome patients and assessed its replicability in a separate cohort of 300 acute respiratory distress syndrome patients. Tidal volume and positive end-expiratory pressure had no impact on mortality. We identified a plateau pressure cut-off value of 29 cm H2O, above which an ordinal increment was accompanied by an increment of risk of death. We identified a driving pressure cut-off value of 19 cm H2O where an ordinal increment was accompanied by an increment of risk of death. When we cross tabulated patients with plateau pressure less than 30 and plateau pressure greater than or equal to 30 with those with driving pressure less than 19 and driving pressure greater than or equal to 19, plateau pressure provided a slightly better prediction of outcome than driving pressure in both the derivation and validation cohorts (p < 0.0000001). Conclusions: Plateau pressure was slightly better than driving pressure in predicting hospital death in patients managed with lung-protective ventilation evaluated on standardized ventilator settings 24 hours after acute respiratory distress syndrome onset.

Impact of Anthropometric Features on the Applicability and Accuracy of FibroScan® (M and XL) in Overweight/Obese Patients.

Transient elastography is the reference method for liver stiffness measurement (LSM) in the general population, having lower applicability in obese patients. We evaluated the applicability and diagnostic accuracy of the M and XL probes in overweight/obese patients to establish the most appropriate approach.