Mortality Due to Acute Respiratory Distress Syndrome in Latin America.

OBJECTIVES: Mortality due to acute respiratory distress syndrome (ARDS) is a major global health problem. Knowledge of epidemiological data on ARDS is crucial to design management, treatment strategies, and optimize resources. There is ample data regarding mortality of ARDS from high-income countries; in this review, we evaluated mortality due to ARDS in Latin America. DATA SOURCES: We searched in PubMed, Cochrane Central Register of Controlled Trials, Web of Science, and Latin American and Caribbean Health Science Literature databases from 1967 to March 2023. STUDY SELECTION: We searched prospective or retrospective observational studies and randomized controlled trials conducted in Latin American countries reporting ARDS mortality. DATA EXTRACTION: Three pairs of independent reviewers checked all studies for eligibility based on their titles and abstracts. We performed meta-analysis of proportions using a random-effects model. We performed sensitivity analyses including studies with low risk of bias and with diagnosis using the Berlin definition. Subgroup analysis comparing different study designs, time of publication (up to 2000 and from 2001 to present), and studies in which the diagnosis of ARDS was made using Pa o2 /F io2 less than or equal to 200 and regional variations. Subsequently, we performed meta-regression analyses. Finally, we graded the certainty of the evidence (Grading of Recommendations Assessment, Development, and Evaluation). DATA SYNTHESIS: Of 3315 articles identified, 32 were included (3627 patients). Mortality was 52% in the pooled group (low certainty of evidence). In the sensitivity analysis (according to the Berlin definition), mortality was 46% (moderate certainty of evidence). In the subgroup analysis mortality was 53% (randomized controlled trials), 51% (observational studies), 66% (studies published up to 2000), 50% (studies after 2000), 44% (studies with Pa o2 /F io2 ≤ 200), 56% (studies from Argentina/Brazil), and 40% (others countries). No variables were associated with mortality in the meta-regression. CONCLUSIONS: ARDS mortality in Latin America remains high, as in other regions. These results should constitute the basis for action planning to improve the prognosis of patients with ARDS (PROSPERO [CRD42022354035]).

High versus low positive end-expiratory pressure (PEEP) levels for mechanically ventilated adult patients with acute lung injury and acute respiratory distress syndrome.

BACKGROUND: In patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), mortality remains high. These patients require mechanical ventilation, which has been associated with ventilator-induced lung injury. High levels of positive end-expiratory pressure (PEEP) could reduce this condition and improve patient survival. This is an updated version of the review first published in 2013. OBJECTIVES: To assess the benefits and harms of high versus low levels of PEEP in adults with ALI and ARDS. SEARCH METHODS: For our previous review, we searched databases from inception until 2013. For this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, LILACS, and the Web of Science from inception until May 2020. We also searched for ongoing trials (www.trialscentral.org; www.clinicaltrial.gov; www.controlled-trials.com), and we screened the reference lists of included studies. SELECTION CRITERIA: We included randomised controlled trials that compared high versus low levels of PEEP in ALI and ARDS participants who were intubated and mechanically ventilated in intensive care for at least 24 hours. DATA COLLECTION AND ANALYSIS: Two review authors assessed risk of bias and extracted data independently. We contacted investigators to identify additional published and unpublished studies. We used standard methodological procedures expected by Cochrane. MAIN RESULTS: We included four new studies (1343 participants) in this review update. In total, we included 10 studies (3851 participants). We found evidence of risk of bias in six studies, and the remaining studies fulfilled all criteria for low risk of bias. In eight studies (3703 participants), a comparison was made between high and low levels of PEEP, with the same tidal volume in both groups. In the remaining two studies (148 participants), the tidal volume was different between high- and low-level groups. In the main analysis, we assessed mortality occurring before hospital discharge only in studies that compared high versus low PEEP, with the same tidal volume in both groups. Evidence suggests that high PEEP may result in little to no difference in mortality compared to low PEEP (risk ratio (RR) 0.97, 95% confidence interval (CI) 0.90 to 1.04; I² = 15%; 7 studies, 3640 participants; moderate-certainty evidence). In addition, high PEEP may result in little to no difference in barotrauma (RR 1.00, 95% CI 0.64 to 1.57; I² = 63%; 9 studies, 3791 participants; low-certainty evidence). High PEEP may improve oxygenation in patients up to the first and third days of mechanical ventilation (first day: mean difference (MD) 51.03, 95% CI 35.86 to 66.20; I² = 85%; 6 studies, 2594 participants; low-certainty evidence; third day: MD 50.32, 95% CI 34.92 to 65.72; I² = 83%; 6 studies, 2309 participants; low-certainty evidence) and probably improves oxygenation up to the seventh day (MD 28.52, 95% CI 20.82 to 36.21; I² = 0%; 5 studies, 1611 participants; moderate-certainty evidence). Evidence suggests that high PEEP results in little to no difference in the number of ventilator-free days (MD 0.45, 95% CI -2.02 to 2.92; I² = 81%; 3 studies, 1654 participants; low-certainty evidence). Available data were insufficient to pool the evidence for length of stay in the intensive care unit. AUTHORS' CONCLUSIONS: Moderate-certainty evidence shows that high levels compared to low levels of PEEP do not reduce mortality before hospital discharge. Low-certainty evidence suggests that high levels of PEEP result in little to no difference in the risk of barotrauma. Low-certainty evidence also suggests that high levels of PEEP improve oxygenation up to the first and third days of mechanical ventilation, and moderate-certainty evidence indicates that high levels of PEEP improve oxygenation up to the seventh day of mechanical ventilation. As in our previous review, we found clinical heterogeneity - mainly within participant characteristics and methods of titrating PEEP - that does not allow us to draw definitive conclusions regarding the use of high levels of PEEP in patients with ALI and ARDS. Further studies should aim to determine the appropriate method of using high levels of PEEP and the advantages and disadvantages associated with high levels of PEEP in different ARDS and ALI patient populations.

Acute Respiratory Distress Syndrome: Mortality in a Single Center According to Different Definitions.

BACKGROUND: Mortality in acute lung injury (ALI) remains high, with outcome data arising mostly from multicenter studies. We undertook this investigation to determine hospital mortality in patients with ALI in a single center. METHODS: We studied patients admitted between 2005 and 2012 with ALI and acute respiratory distress syndrome (ARDS) according to the American European Consensus Conference (AECC) criteria and recorded clinical variables. Thereafter, patients were classified as subgroups according to the AECC and Berlin definition in order to compare the clinical characteristics and outcomes. RESULTS: In the 93 patients comprising the study, hospital mortality was 38%. Mortality at 28 days was 36%. Multivariate analysis associated hospital mortality with age and Pao2/Fio2 on day 1 ( P < .001). Differences resulted between the subgroups of AECC (ALI vs ARDS) and Berlin (mild vs moderate vs severe ARDS) in the lung injury score, Pao2/Fio2, Pao2/PAo2, PaCo2 on day 1, and hospital mortality. CONCLUSION: The overall hospital mortality (38%) was similar to that of other studies and according to the presence of ARDS (Pao2/Fio2 ≤ 200), we found significant differences between ALI and ARDS (AECC) and between mild and moderate or severe ARDS (Berlin) in baseline respiratory variables and mortality.

High versus low positive end-expiratory pressure (PEEP) levels for mechanically ventilated adult patients with acute lung injury and acute respiratory distress syndrome.

BACKGROUND: Mortality in patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) remains high. These patients require mechanical ventilation, but this modality has been associated with ventilator-induced lung injury. High levels of positive end-expiratory pressure (PEEP) could reduce this condition and improve patient survival. OBJECTIVES: To assess the benefits and harms of high versus low levels of PEEP in patients with ALI and ARDS. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2013, Issue 4), MEDLINE (1950 to May 2013), EMBASE (1982 to May 2013), LILACS (1982 to May 2013) and SCI (Science Citation Index). We used the Science Citation Index to find references that have cited the identified trials. We did not specifically conduct manual searches of abstracts of conference proceedings for this review. We also searched for ongoing trials (www.trialscentral.org; www.clinicaltrial.gov and www.controlled-trials.com).     SELECTION CRITERIA: We included randomized controlled trials that compared the effects of two levels of PEEP in ALI and ARDS participants who were intubated and mechanically ventilated in intensive care for at least 24 hours. DATA COLLECTION AND ANALYSIS: Two review authors assessed the trial quality and extracted data independently. We contacted investigators to identify additional published and unpublished studies.  MAIN RESULTS: We included seven studies that compared high versus low levels of PEEP (2565 participants). In five of the studies (2417 participants), a comparison was made between high and low levels of PEEP with the same tidal volume in both groups, but in the remaining two studies (148 participants), the tidal volume was different between high- and low-level groups. We saw evidence of risk of bias in three studies, and the remaining studies fulfilled all criteria for adequate trial quality.In the main analysis, we assessed mortality occurring before hospital discharge only in those studies that compared high versus low PEEP with the same tidal volume in both groups. With the three studies that were included, the meta-analysis revealed no statistically significant differences between the two groups (relative risk (RR) 0.90, 95% confidence interval (CI) 0.81 to 1.01), nor was any statistically significant difference seen in the risk of barotrauma (RR 0.97, 95% CI 0.66 to 1.42). Oxygenation was improved in the high-PEEP group, although data derived from the studies showed a considerable degree of statistical heterogeneity. The number of ventilator-free days showed no significant difference between the two groups. Available data were insufficient to allow pooling of length of stay in the intensive care unit (ICU). The subgroup of participants with ARDS showed decreased mortality in the ICU, although it must be noted that in two of the three included studies, the authors used a protective ventilatory strategy involving a low tidal volume and high levels of PEEP. AUTHORS' CONCLUSIONS: Available evidence indicates that high levels of PEEP, as compared with low levels, did not reduce mortality before hospital discharge. The data also show that high levels of PEEP produced no significant difference in the risk of barotrauma, but rather improved participants' oxygenation to the first, third, and seventh days. This review indicates that the included studies were characterized by clinical heterogeneity.  

Mortality in Critically Ill Elderly Individuals Receiving Mechanical Ventilation.

BACKGROUND: Previous studies that evaluated mortality in elderly subjects who received mechanical ventilation had conflicting results. The aim of this systematic review was to evaluate the effects of age on mortality. METHODS: A number of medical literature databases and the references listed (from 1974 to May 2015) were searched for studies that compared 2 different age groups. The primary outcome was mortality in subjects ages ≥ 65 y. The severity scores, ICU and hospital lengths of stay, and the presence of ventilator-associated pneumonia were secondary outcomes. Finally, mortality in the subjects with ARDS and of cutoff ages 70 and 80 y was assessed by subgroup analysis. Evidence quality was assessed by the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) criteria score. RESULTS: Of the 5,182 articles identified, 21 were included. Subjects ages ≥ 65 y had higher mortalities (odds ratio [OR] 1.80, 95% CI 1.56-2.08; I2 = 71%). APACHE (Acute Physiology and Chronic Health Evaluation) II revealed intergroup differences (mean difference 3.07, 95% CI 2.52-3.61; I2 = 0%), whereas neither the ICU nor hospital length of stay (mean difference 1.27, 95% CI -0.82 to 3.36, I2 = 82%, and mean difference 1.29, 95% CI -0.71 to 3.29, I2 = 0%, respectively) nor the groups in the 2 studies that assessed ventilator-associated pneumonia exhibited any difference. Subgroup analysis revealed a higher mortality in the older subjects, in the subjects with ARDS (OR 1.76, 95% CI 1.30-2.36; I2 = 0%) and in the subjects ages 70 and 80 y (OR 1.78, 95% CI 1.51-2.10, I2 = 71%; and OR 1.96, 95% CI 1.81-2.13, I2 = 0%, respectively). The quality of associated evidence was low or very low. CONCLUSIONS: Although low-quality evidence was available, we conclude that age is associated with a greater mortality in critical subjects who were receiving mechanical ventilation.

Multilayer perceptron architecture optimization using parallel computing techniques.

The objective of this research was to develop a methodology for optimizing multilayer-perceptron-type neural networks by evaluating the effects of three neural architecture parameters, namely, number of hidden layers (HL), neurons per hidden layer (NHL), and activation function type (AF), on the sum of squares error (SSE). The data for the study were obtained from quality parameters (physicochemical and microbiological) of milk samples. Architectures or combinations were organized in groups (G1, G2, and G3) generated upon interspersing one, two, and three layers. Within each group, the networks had three neurons in the input layer, six neurons in the output layer, three to twenty-seven NHL, and three AF (tan-sig, log-sig, and linear) types. The number of architectures was determined using three factorial-type experimental designs, which reached 63, 2 187, and 50 049 combinations for G1, G2 and G3, respectively. Using MATLAB 2015a, a logical sequence was designed and implemented for constructing, training, and evaluating multilayer-perceptron-type neural networks using parallel computing techniques. The results show that HL and NHL have a statistically relevant effect on SSE, and from two hidden layers, AF also has a significant effect; thus, both AF and NHL can be evaluated to determine the optimal combination per group. Moreover, in the three study groups, it is observed that there is an inverse relationship between the number of processors and the total optimization time.