Increased mortality of older patients with acute respiratory distress syndrome

A pretrain-finetune approach for improving model generalizability in outcome prediction of acute respiratory distress syndrome patients

BACKGROUND

Early prediction of acute respiratory distress syndrome (ARDS) of critically ill patients in intensive care units (ICUs) has been intensively studied in the past years. Yet a prediction model trained on data from one hospital might not be well generalized to other hospitals. It is therefore essential to develop an accurate and generalizable ARDS prediction model adaptive to different hospital or medical centers.

METHODS

We analyzed electronic medical records of 200,859 and 50,920 hospitalized patients within 24 h after being diagnosed with ARDS from the Philips eICU Institute (eICU-CRD) and the Medical Information Mart for Intensive Care (MIMIC-IV) dataset, respectively. Patients were sorted into three groups, including rapid death, long stay, and recovery, based on their condition or outcome between 24 and 72 h after ARDS diagnosis. To improve prediction performance and generalizability, a "pretrain-finetune" approach was applied, where we pretrained models on the eICU-CRD dataset and performed model finetuning using only a part (35%) of the MIMIC-IV dataset, and then tested the finetuned models on the remaining data from the MIMIC-IV dataset. Well-known machine-learning algorithms, including logistic regression, random forest, extreme gradient boosting, and multilayer perceptron neural networks, were employed to predict ARDS outcomes. Prediction performance was evaluated using the area under the receiver-operating characteristic curve (AUC).

RESULTS

Results show that, in general, multilayer perceptron neural networks outperformed the other models. The use of pretrain-finetune yielded improved performance in predicting ARDS outcomes achieving a micro-AUC of 0.870 for the MIMIC-IV dataset, an improvement of 0.046 over the pretrain model.

CONCLUSIONS

The proposed pretrain-finetune approach can effectively improve model generalizability from one to another dataset in ARDS prediction.

Postoperative acute respiratory distress syndrome in randomized controlled trials

BACKGROUND

Acute respiratory distress syndrome is a potentially fatal postoperative complication. We aimed to estimate temporal trends of the representation of patients with postoperative acute respiratory distress syndrome in clinical trials, determine their distinct clinical features, and identify predictors of mortality.

METHODS

This is a secondary analysis of 7 randomized controlled clinical trials conducted by the Acute Respiratory Distress Syndrome Network and the Clinical Trials Network for the Prevention and Early Treatment of Acute Lung Injury. Patients with acute respiratory distress syndrome were classified into a postoperative acute respiratory distress syndrome group (ie, patients who had undergone elective surgery in the immediate period before trial enrollment) and a non-postoperative acute respiratory distress syndrome group.

RESULTS

Out of 5,316 patients with acute respiratory distress syndrome, 256 (4.8%) had postoperative acute respiratory distress syndrome. Representation of postoperative acute respiratory distress syndrome in trials gradually declined from 2000 to 2011, but it remained stable afterward at 2.7%. Postoperative acute respiratory distress syndrome was associated with lower 90-day mortality (24.6% vs 30.9%, P = .032) than non-postoperative acute respiratory distress syndrome, even after adjusting for age, acute respiratory distress syndrome severity, usage of vasopressors at baseline, and the study publication year (hazard ratio 0.63, 95% confidence interval 0.49-0.82). Age (odds ratio 1.07, 95% confidence interval 1.04-1.09), immunosuppression (odds ratio 4.12, 95% confidence interval 1.43-11.86), and positive fluid balance (odds ratio 1.09, 95% confidence interval 1.04-1.14) were associated with 90-day mortality among patients with postoperative acute respiratory distress syndrome.

CONCLUSION

Representation of postoperative acute respiratory distress syndrome in trials of the Acute Respiratory Distress Syndrome Network and the Clinical Trials Network for the Prevention and Early Treatment of Acute Lung Injury gradually declined from 2000 to 2011 but remained stable afterward. Postoperative acute respiratory distress syndrome was associated with lower mortality than non-postoperative acute respiratory distress syndrome. These findings may put both temporal trends and the prognosis of postoperative acute respiratory distress syndrome in perspective. Also, positive fluid balance was associated with the mortality of patients with postoperative acute respiratory distress syndrome.

Timing of Lung Transplant Referral in Patients with Severe COVID-19 Lung Injury Supported by ECMO

Severe respiratory failure caused by COVID-19 often requires mechanical ventilation, including extracorporeal membrane oxygenation (ECMO). In rare cases, lung transplantation (LTx) may be considered as a last resort. However, uncertainties remain about patient selection and optimal timing for referral and listing. This retrospective study analyzed patients with severe COVID-19 who were supported by veno-venous ECMO and listed for LTx between July 2020 and June 2022. Out of the 20 patients in the study population, four who underwent LTx were excluded. The clinical characteristics of the remaining 16 patients were compared, including nine who recovered and seven who died while awaiting LTx. The median duration from hospitalization to listing was 85.5 days, and the median duration on the waitlist was 25.5 days. Younger age was significantly associated with a higher likelihood of recovery without LTx after a median of 59 days on ECMO, compared to those who died at a median of 99 days. In patients with severe COVID-19-induced lung damage supported by ECMO, referral to LTx should be delayed for 8-10 weeks after ECMO initiation, particularly for younger patients who have a higher probability of spontaneous recovery and may not require LTx.

Neutrophilic Pleuritis Is a Severe Complication of Klebsiella pneumoniae Pneumonia in Old Mice

The pathomechanisms underlying the frequently observed fatal outcome of Klebsiella pneumoniae pneumonia in elderly patients are understudied. In this study, we examined the early antibacterial immune response in young mice (age 2-3 mo) as compared with old mice (age 18-19 mo) postinfection with K. pneumoniae. Old mice exhibited significantly higher bacterial loads in lungs and bacteremia as early as 24 h postinfection compared with young mice, with neutrophilic pleuritis nearly exclusively developing in old but not young mice. Moreover, we observed heavily increased cytokine responses in lungs and pleural spaces along with increased mortality in old mice. Mechanistically, Nlrp3 inflammasome activation and caspase-1-dependent IL-1β secretion contributed to the observed hyperinflammation, which decreased upon caspase-1 inhibitor treatment of K. pneumoniae-infected old mice. Irradiated old mice transplanted with the bone marrow of young mice did not show hyperinflammation or early bacteremia in response to K. pneumoniae. Collectively, the accentuated lung pathology observed in K. pneumoniae-infected old mice appears to be due to regulatory defects of the bone marrow but not the lung, while involving dysregulated activation of the Nlrp3/caspase-1/IL-1β axis.

New Insights into the Alveolar Epithelium as a Driver of Acute Respiratory Distress Syndrome

The alveolar epithelium serves as a barrier between the body and the external environment. To maintain efficient gas exchange, the alveolar epithelium has evolved to withstand and rapidly respond to an assortment of inhaled, injury-inducing stimuli. However, alveolar damage can lead to loss of alveolar fluid barrier function and exuberant, non-resolving inflammation that manifests clinically as acute respiratory distress syndrome (ARDS). This review discusses recent discoveries related to mechanisms of alveolar homeostasis, injury, repair, and regeneration, with a contemporary emphasis on virus-induced lung injury. In addition, we address new insights into how the alveolar epithelium coordinates injury-induced lung inflammation and review maladaptive lung responses to alveolar damage that drive ARDS and pathologic lung remodeling.

Acute Respiratory Distress Syndrome in the Elderly

Acute respiratory distress syndrome (ARDS) is a commonly encountered complex syndrome of varied etiology and outcomes. The elderly population is at a high risk of developing severe ARDS with poor outcomes. The age-related changes in the immune system, structural and functional modifications of the respiratory system, and the frailty with a decrease in the physiological reserve of organ systems place them precariously for poor outcomes. However, does age alone influence the outcomes or is it the associated comorbidities that determine mortality in the elderly is not clearly known.

HOW TO CITE THIS ARTICLE

Jagathkar G. Acute Respiratory Distress Syndrome in the Elderly. Indian J Crit Care Med 2021;25(6):613-614.

Aging Influences the Metabolic and Inflammatory Phenotype in an Experimental Mouse Model of Acute Lung Injury

Increased age is a risk factor for poor outcomes from respiratory failure and acute respiratory distress syndrome (ARDS). In this study, we sought to define age-related differences in lung inflammation, muscle injury, and metabolism after intratracheal lipopolysaccharide (IT-LPS) acute lung injury (ALI) in adult (6 months) and aged (18-20 months) male C57BL/6 mice. We also investigated age-related changes in muscle fatty acid oxidation (FAO) and the consequences of systemic FAO inhibition with the drug etomoxir. Aged mice had a distinct lung injury course characterized by prolonged alveolar neutrophilia and lack of response to therapeutic exercise. To assess the metabolic consequences of ALI, aged and adult mice underwent whole body metabolic phenotyping before and after IT-LPS. Aged mice had prolonged anorexia and decreased respiratory exchange ratio, indicating increased reliance on FAO. Etomoxir increased mortality in aged but not adult ALI mice, confirming the importance of FAO on survival from acute severe stress and suggesting that adult mice have increased resilience to FAO inhibition. Skeletal muscles from aged ALI mice had increased transcription of key fatty acid metabolizing enzymes, CPT-1b, LCAD, MCAD, FATP1 and UCP3. Additionally, aged mice had increased protein levels of CPT-1b at baseline and after lung injury. Surprisingly, CPT-1b in isolated skeletal muscle mitochondria had decreased activity in aged mice compared to adults. The distinct phenotype of aged ALI mice has similar characteristics to the adverse age-related outcomes of ARDS. This model may be useful to examine and augment immunologic and metabolic abnormalities unique to the critically ill aged population.

Etiology and Outcomes of ARDS in the Elderly Population in an Intensive Care Unit in North India

Background

Whether age would impact the outcomes in subjects with acute respiratory distress syndrome (ARDS) remains unclear. Herein, we study the effect of age as a predictor of mortality in ARDS.

Materials and methods

We categorized consecutive subjects with ARDS as either ARDS_elderly (age >65 years) or ARDSnon_elderly (age ≤65 years) admitted to the respiratory intensive care unit (ICU) of a tertiary care hospital in North India between January 2007 and December 2019. We compared the baseline clinical and demographic characteristics, lung mechanics, and mortality between the two groups. We also analyzed the factors predicting ICU survival using multivariate logistic regression analysis.

Results

We included 625 patients (ARDS_elderly, 140 [22.4%] and ARDS_nonelderly, 485 [77.6%]) with a mean (standard deviation) age (56.3% males) of 40.6 (17.8) years. The ARDS_elderly were more likely (p = 0.0001) to have the presence of any comorbid illness compared to ARDS_nonelderly. The elderly subjects had significantly higher pulmonary ARDS than the younger group. The severity of ARDS was however, similarly distributed between the two study arms. There were 224 (35.8%) deaths, and the mortality was significantly higher (p = 0.012) in the ARDS_elderly than the to ARDS_nonelderly (ARDS_elderly vs ARDS_nonelderly, 45 vs 33.2%). On multivariate logistic regression analysis, the baseline sequential organ failure assessment scores, presence of pulmonary ARDS, and the development of new organ dysfunction were the independent predictors of mortality.

Conclusion

The outcomes in subjects with ARDS are dependent on the severity of illness at admission and the etiology of ARDS rather than the age alone.

How to cite this article

Sehgal IS, Agarwal R, Dhooria S, Prasad KT, Muthu V, Aggarwal AN. Etiology and Outcomes of ARDS in the Elderly Population in an Intensive Care Unit in North India. Indian J Crit Care Med 2021;25(6):648–654.

Aging impairs alveolar epithelial type II cell function in acute lung injury

Morbidity and mortality rates in acute lung injury (ALI) increase with age. As alveolar epithelial type II cells (AE2) are crucial for lung function and repair, we hypothesized that aging promotes senescence in AE2 and contributes to the severity and impaired regeneration in ALI. ALI was induced with 2.5 μg lipopolysaccharide/g body weight in young (3 mo) and old (18 mo) mice that were euthanized 24 h, 72 h, and 10 days later. Lung function, pulmonary surfactant activity, stereology, cell senescence, and single-cell RNA sequencing analyses were performed to investigate AE2 function in aging and ALI. In old mice, surfactant activity was severely impaired. A 60% mortality rate and lung function decline were observed in old, but not in young, mice with ALI. AE2 of young mice adapted to injury by increasing intracellular surfactant volume and proliferation rate. In old mice, however, this adaptive response was compromised, and AE2 of old mice showed signs of cell senescence, increased inflammatory signaling, and impaired surfactant metabolism in ALI. These findings provide evidence that ALI promotes a limited proliferation rate, increased inflammatory response, and surfactant dysfunction in old, but not in young, mice, supporting an impaired regenerative capacity and reduced survival rate in ALI with advancing age.

The Impact of Aging in Acute Respiratory Distress Syndrome: A Clinical and Mechanistic Overview

Acute respiratory distress syndrome (ARDS) is associated with increased morbidity and mortality in the elderly population (≥65 years of age). Additionally, age is widely reported as a risk factor for the development of ARDS. However, the underlying pathophysiological mechanisms behind the increased risk of developing, and increased severity of, ARDS in the elderly population are not fully understood. This is compounded by the significant heterogeneity observed in patients with ARDS. With an aging population worldwide, a better understanding of these mechanisms could facilitate the development of therapies to improve outcomes in this population. In this review, the current clinical evidence of age as a risk factor and prognostic indicator in ARDS and the potential underlying mechanisms that may contribute to these factors are outlined. In addition, research on age-dependent treatment options and biomarkers, as well as future prospects for targeting these underlying mechanisms, are discussed.

Incidence and outcomes of acute respiratory distress syndrome in intensive care units of mainland China: a multicentre prospective longitudinal study

OBJECTIVES

To evaluate the incidence and mortality of acute respiratory distress syndrome (ARDS) in medical/respiratory intensive care units (MICUs/RICUs) to assess ventilation management and the use of adjunct therapy in routine clinical practice for patients fulfilling the Berlin definition of ARDS in mainland China.

METHODS

This was a multicentre prospective longitudinal study. Patients who met the Berlin definition of ARDS were included. Baseline data and data on ventilator management and the use of adjunct therapy were collected.

RESULTS

Of the 18,793 patients admitted to participating ICUs during the study timeframe, 672 patients fulfilled the Berlin ARDS criteria and 527 patients were included in the analysis. The most common predisposing factor for ARDS in 402 (77.0) patients was pneumonia. The prevalence rates were 9.7% (51/527) for mild ARDS, 47.4% (250/527) for moderate ARDS, and 42.9% (226/527) for severe ARDS. In total, 400 (75.9%) patients were managed with invasive mechanical ventilation during their ICU stays. All ARDS patients received a tidal volume of 6.8 (5.8-7.9) mL/kg of their predicted body weight and a positive end-expository pressure (PEEP) of 8 (6-12) cmH₂O. Recruitment manoeuvres (RMs) and prone positioning were used in 61 (15.3%) and 85 (16.1%) ventilated patients, respectively. Life-sustaining care was withdrawn from 92 (17.5%) patients. When these patients were included in the mortality analysis, 244 (46.3%) ARDS patients (16 (31.4%) with mild ARDS, 101 (40.4%) with moderate ARDS, and 127 (56.2%) with severe ARDS) died in the hospital.

CONCLUSIONS

Among the 18 ICUs in mainland China, the incidence of ARDS was low. The rates of mortality and withdrawal of life-sustaining care were high. The recommended lung protective strategy was followed with a high degree of compliance, but the implementation of adjunct treatment was lacking. These findings indicate the potential for improvement in the management of patients with ARDS in China.

TRIAL REGISTRATION

Clinicaltrials.gov NCT02975908 . Registered on 29 November 2016-retrospectively registered.

The acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a prevalent cause of acute respiratory failure with high rates of mortality, as well as short- and long-term complications, such as physical and cognitive impairment. Therefore, early recognition of this syndrome and application of well-demonstrated therapeutic interventions are essential to change the natural course of this entity and bring about positive clinical outcomes. In this article, we review updated concepts in ARDS. Specifically, we discuss the current definition of ARDS, its risk factors, and the evidence supporting ventilation management, adjunctive therapies, and interventions required in refractory hypoxemia.

Older Adult Patients Are at Lower Risk of ARDS Compared to Younger Patients at Risk: Secondary Analysis of a Multicenter Cohort Study

INTRODUCTION

Older adult individuals often have acute illnesses predisposing them to developing acute respiratory distress syndrome (ARDS). We aimed to identify the relationship between age and the development of ARDS in a cohort of hospitalized patients.

METHODS

This was a secondary analysis of a prospective multicenter observational cohort study of hospitalized patients at risk of developing ARDS admitted to 22 hospitals from March 2009 to August 2009. Patients were classified as older adults if their age was 80 or greater. A multivariable logistic regression was performed, adjusting for severity of illness via Acute Physiology and Chronic Health Evaluation (APACHE II) and risk of ARDS via Lung Injury Prediction Score.

RESULTS

Of 5584 patients, 377 (6.8%) developed ARDS. Twenty-four (3.5%) of 694 patients aged 80 or older developed ARDS, compared to 353 (7.2%) of 4890 patients aged less than 80 (P < .001). After adjusting for severity of illness and the risk of ARDS development, older adult patients had a lower incidence of ARDS compared to younger individuals (odds ratio: 0.28, 95% confidence interval: 0.18-0.42).

CONCLUSION

Older adult patients aged 80 years or older have a reduced incidence of ARDS compared to younger patients, after adjusting for severity of illness and risk of ARDS development.

The Role of Pulmonary and Systemic Immunosenescence in Acute Lung Injury

Acute lung injury (ALI) is associated with increased morbidity and mortality in the elderly (> 65 years), but the knowledge about origin and effects of immunosenescence in ALI is limited. Here, we investigated the immune response at pulmonary, systemic and cellular level in young (2-3 months) and old (18-19 months) C57BL/6J mice to localize and characterize effects of immunosenescence in ALI. ALI was induced by intranasal lipopolysaccharide (LPS) application and the animals were sacrificed 24 or 72 h later. Pulmonary inflammation was investigated by analyzing histopathology, bronchoalveolar lavage fluid (BALF) cytometry and cytokine expression. Systemic serum cytokine expression, spleen lymphocyte populations and the gut microbiome were analyzed, as well as activation of alveolar and bone marrow derived macrophages (BMDM) in vitro. Pulmonary pathology of ALI was more severe in old compared with young mice. Old mice showed significantly more inflammatory cells and pro-inflammatory cyto- or chemokines (TNFα, IL-6, MCP-1, CXCL1, MIP-1α) in the BALF, but a delayed expression of cytokines associated with activation of adaptive immunity and microbial elimination (IL-12 and IFNγ). Alveolar macrophages, but not BMDM, of old mice showed greater activation after in vivo and in vitro stimulation with LPS. No systemic enhanced pro-inflammatory cytokine response was detected in old animals after LPS exposure, but a delayed expression of IL-12 and IFNγ. Furthermore, old mice had less CD8⁺ T-cells and NK cells and more regulatory T-cells in the spleen compared with young mice and a distinct gut microbiome structure. The results of our study show an increased alveolar macrophage activation and pro-inflammatory signaling in the lungs, but not systemically, suggesting a key role of senescent alveolar macrophages in ALI. A decrease in stimulators of adaptive immunity with advancing age might further promote the susceptibility to a worse prognosis in ALI in elderly.

Differential Regulation of NF-κB and Nrf2 by Bojungikki-Tang Is Associated with Suppressing Lung Inflammation

Bojungikki-tang (BT), an Asian herbal remedy, has been prescribed to increase the vitality of debilitated patients. Since a compromised, weakened vitality often leads to illness, BT has been widely used to treat various diseases. However, little is known about the mechanism by which BT exerts its effect. Given that BT ameliorates inflammatory pulmonary diseases including acute lung injury (ALI), we investigated whether BT regulates the function of key inflammatory factors such as NF-κB and Nrf2, contributing to suppressing inflammation. Results show that BT interrupted the nuclear localization of NF-κB and suppressed the expression of the NF-κB-dependent genes in RAW 264.7 cells. In similar experiments, BT induced the nuclear localization of Nrf2 and the expression of the Nrf2-dependent genes. In a lipopolysaccharide-induced ALI mouse model, a single intratracheal administration of BT to mouse lungs ameliorated alveolar structure and suppressed the expression of proinflammatory cytokine genes and neutrophil infiltration to mouse lungs. Therefore, our findings suggest that suppression of NF-κB and activation of Nrf2, by which BT suppresses inflammation, are ways for BT to exert its effect.

The effect of demographics and patient location on the outcome of patients with acute respiratory distress syndrome

OBJECTIVE

Outcome of acute respiratory distress syndrome (ARDS) in relation to age, gender, race, pre-Intensive Care Unit (ICU) location, and type of ICU.

METHODS

Retrospective cohort study of patients enrolled in the ARDS network randomized controlled trials.

RESULTS

A total of 2914 patients were included in these trials. Outcomes were adjusted to baseline covariates including APACHE III score, vasopressor use, cause of lung injury, lung injury score, diabetes, cancer status, body mass index, and study ID. Older patients had significantly higher mortality at both 28- and 60-day (odds ratio [OR] 2.59 [95% confidence interval [CI]: 2.12-3.18] P < 0.001 and 2.79, 95% CI: 2.29-3.39, P < 0.001, respectively); less ICU and ventilator free days (relative risk [RR] 0.92, 95% CI: 0.87-0.96, P < 0.001 and 0.92, 95% CI: 0.88-0.96, P < 0.001, respectively). For preadmission location, the 28- and 60-day mortality were lower if the patient was admitted from the operating room (OR)/recovery room (OR 0.65, 95% CI: 0.44-0.95, P = 0.026; and OR = 0.66, 95% CI: 0.46-0.95, P = 0.025, respectively) or emergency department (OR = 0.78, 95% CI: 0.61-0.99, P = 0.039; and OR = 0.71, 95% CI: 0.56-0.89, P = 0.004, respectively), but no statistical differences in ICU and ventilator free days between different preadmission locations. Races other than white and black had a statistically higher mortality (28- and 60-day mortality: OR = 1.47, 95% CI: 1.09-1.98, P = 0.011; and OR 1.53, 95% CI: 1.15-2.04, P = 0.004, respectively). Between whites and blacks, females and males there were no statistically significant differences in all outcomes.

CONCLUSION

Older patients and races other than blacks and whites have higher mortality associated with ARDS. Mortality is affected by patients preadmission location. There are no differences in outcome in relation to the type of ICU, gender, or between blacks and whites.

Aging exacerbates acute lung injury-induced changes of the air-blood barrier, lung function, and inflammation in the mouse

Acute lung injury (ALI) is characterized by hypoxemia, enhanced permeability of the air-blood barrier, and pulmonary edema. Particularly in the elderly, ALI is associated with increased morbidity and mortality. The reasons for this, however, are poorly understood. We hypothesized that age-related changes in pulmonary structure, function, and inflammation lead to a worse prognosis in ALI. ALI was induced in young (10 wk old) and old (18 mo old) male C57BL/6 mice by intranasal application of 2.5 mg lipopolysaccharide (LPS)/kg body wt or saline (control mice). After 24 h, lung function was assessed, and lungs were either processed for stereological or inflammatory analysis, such as bronchoalveolar lavage fluid (BALF) cytometry and qPCR. Both young and old mice developed severe signs of ALI, including alveolar and septal edema and enhanced inflammatory BALF cells. However, the pathology of ALI was more pronounced in old compared with young mice with nearly sixfold higher BALF protein concentration, twice the number of neutrophils, and significantly higher expression of neutrophil chemokine Cxcl1, adhesion molecule Icam-1, and metalloprotease-9, whereas the expression of tight junction protein occludin significantly decreased. The old LPS mice had thicker alveolar septa attributable to higher volumes of interstitial cells and extracellular matrix. Tissue resistance and elastance reflected observed changes at the ultrastructural level in the lung parenchyma in ALI of young and old mice. In summary, the pathology of ALI with advanced age in mice is characterized by a greater neutrophilic inflammation, leakier air-blood barrier, and altered lung function, which is in line with findings in elderly patients.

Intensive care and invasive ventilation in the elderly patient, implications of chronic lung disease and comorbidities

Aims: Elderly patients have an increasing prevalence of illness that requires consideration of critical care and invasive ventilatory support. Although critical care of even the very elderly can provide value, with increasing age the potential risks of treatment and diminishing returns with respect to quality and quantity of life result in a need for careful evaluation. Variable combinations of impaired organ function, active disease and residual pathology from past disease and injury all affect critical care, with the consequence that the elderly are a very heterogeneous population. Recognizing that critical care is a limited resource, it is important to identify patients who may be at increased risk or least likely to benefit from treatment. Patients with functional impairments, nutritional deficiencies and multiple comorbidities may be at highest risk of poor outcomes. Those with very severe disease, extreme age and requirements for prolonged ventilatory support have high in-hospital mortality. Functional impairments, comorbidities and severity of illness are usually more important considerations than chronologic age. The objective of this review is to identify how common problems of the elderly affect critical care and decisions concerning use of invasive ventilatory support.

The acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a major cause of acute respiratory failure. Its development leads to high rates of mortality, as well as short- and long-term complications, such as physical and cognitive impairment. Therefore, early recognition of this syndrome and application of demonstrated therapeutic interventions are essential to change the natural course of this devastating entity. In this review article, we describe updated concepts in ARDS. Specifically, we discuss the new definition of ARDS, its risk factors and pathophysiology, and current evidence regarding ventilation management, adjunctive therapies, and intervention required in refractory hypoxemia.

Survival predictors in acute respiratory distress syndrome with extracorporeal membrane oxygenation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) can be used as a salvage therapy, but the effectiveness is controversial. The aim of this study was to investigate the predictors of mortality and the influence of organ dysfunction scores in severe acute respiratory distress syndrome (ARDS) patients treated with ECMO.

METHODS

The records of adult severe ARDS patients receiving ECMO support from May 2006 to December 2011 at Chang Gung Memorial Hospital were retrospectively analyzed.

RESULTS

The records of 65 patients with severe ARDS who received venovenous ECMO were analyzed. The hospital survival rate was 47.7%. Survivors were younger than nonsurvivors (41.4 ± 15.4 versus 54.1 ± 16.9 years, respectively; p = 0.002) and had shorter duration of mechanical ventilation before ECMO (52.7 ± 51.1 versus 112.1 ± 101.0 hours, respectively; p = 0.01). Before ECMO, Acute Physiology and Chronic Health Evaluation II, Sequential Organ Failure Assessment, and Multiple Organ Dysfunction scores were significantly lower for survivors than for nonsurvivors. Mortality rate increased with rising predictive score. During 7 days of ECMO use, organ dysfunction scores were significantly lower for survivors than nonsurvivors.

CONCLUSIONS

Severe ARDS patients who are younger, have shorter duration of mechanical ventilation, and lower organ dysfunction scores before ECMO initiation have more favorable survival outcome. Early application of ECMO, especially if predictive score is below 2, may improve survival. Organ dysfunction scores before and during ECMO support are correlated with survival.

The impact of age on outcomes of elderly ED patients ventilated due to community acquired pneumonia

OBJECTIVES

There is no consensus on whether mechanical ventilation should be initiated for advanced age with community-acquired pneumonia (CAP). This study investigated the effects of age on the outcomes of mechanical ventilation in the emergency department (ED) for advanced age with CAP.

METHODS

We retrospectively investigated the medical records of advanced age (age, ≥65 years) with CAP who required mechanical ventilation in the ED of our hospital between January 2006 and December 2012. The patients were divided into 65 to 74, 75 to 84, and 85 years or older age groups. The following outcomes were measured: number of patients weaned from mechanical ventilation, in-hospital mortality, ventilator-free days, and intensive care unit days. Multiple logistic regression analysis was used to identify risk factors associated with mortality and weaning from mechanical ventilation.

RESULTS

Seventy-one patients (mean age, 79.5 years) were included. The overall in-hospital mortality rate was 43.7%. No significant differences were observed among the 3 groups with regard to weaning from mechanical ventilation (P=.59), in-hospital mortality (P=.90), ventilator-free days (P=.83), or intensive care unit days (P=.12). Age was not significantly associated with weaning from mechanical ventilation or in-hospital mortality among advanced age. Diabetes mellitus was an independent factor for weaning from mechanical ventilation (P=.048) and was relatively associated with mortality (P=.051).

CONCLUSIONS

Age, in itself, may not be a factor limiting the initiation of mechanical ventilation in the ED in advanced age with CAP. Further studies should determine appropriate indications for mechanical ventilation in the ED for these patients.

In vivo platelet activation in critically ill patients with primary 2009 influenza A(H1N1)

BACKGROUND

Changes in platelet reactivity during 2009 influenza A(H1N1) (A[H1N1]) have not been characterized.

METHODS

We prospectively examined platelet activation and cytokine responses in patients with A(H1N1) (n = 20), matched patients with bacterial pneumonia (n = 15), and nonhospitalized, healthy control subjects (n = 10).

RESULTS

Platelet-monocyte aggregation was higher in patients with A(H1N1) (21.4% ± 4.7%) compared with patients with pneumonia (10.9% ± 3.7%) and control subjects (8.1% ± 4.5%, P < .05). Similarly, PAC-1 (antibody that binds to the active conformation of integrin α(IIb)β(3)) binding to platelets is increased in patients with A(H1N1) (9.5% ± 4.7%) compared with patients with pneumonia (1.0% ± 0.7%) and healthy subjects (0.61% ± 0.15%, P < .10). PAC-1 binding was twofold higher in patients with A(H1N1) with shock vs those without shock. IL-6 levels were elevated in patients with A(H1N1), indicating systemic inflammation consistent with activation of circulating platelets.

CONCLUSIONS

These findings, derived from a small but documented cohort of patients, demonstrate that platelet activation responses during A(H1N1) are enhanced-exceeding responses in patients with bacterial pneumonia-and provide new evidence that platelets may contribute to inflammatory responses during A(H1N1).

Acute respiratory distress syndrome: pathophysiology and therapeutic options

Acute Respiratory Distress Syndrome (ARDS) is a common entity in critical care. ARDS is associated with many diagnoses, including trauma and sepsis, can lead to multiple organ failure and has high mortality. The present article is a narrative review of the literature on ARDS, including ARDS pathophysiology and therapeutic options currently being evaluated or in use in clinical practice. The literature review covers relevant publications until January 2011. Recent developments in the therapeutic approach to ARDS include refinements of mechanical ventilatory support with emphasis on protective lung ventilation using low tidal volumes, increased PEEP with use of recruitment maneuvers to promote reopening of collapsed lung alveoli, prone position as rescue therapy for severe hypoxemia, and high frequency ventilation. Supportive measures in the management of ARDS include attention to fluid balance, restrictive transfusion strategies, and minimization of sedatives and neuromuscular blocking agents. Inhaled bronchodilators such as inhaled nitric oxide and prostaglandins confer short term improvement without proven effect on survival, but are currently used in many centers. Use of corticosteroids is also important, and appropriate timely use may reduce mortality. Finally, extra corporeal oxygenation methods are very useful as rescue therapy in patients with intractable hypoxemia, even though a survival benefit has not, to this date been demonstrated. Despite intense ongoing research on the pathophysiology and treatment of ARDS, mortality remains high. Many pharmacologic and supportive strategies have shown promising results, but data from large randomized clinical trials are needed to fully evaluate the true effectiveness of these therapies.

Epidemiology of ARDS and ALI

Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are distinctly modern clinical entities. Recent epidemiologic research has taken advantage of large cohorts in efforts to better describe these highly lethal syndromes with a focus on differentiation of clinically meaningful subtypes and early prediction in an effort to improve treatment and prevention. This article identifies the most significant studies and systematic reviews of recent years, defining the incidence, mortality, risk and prognostic factors, and etiologic classes of ARDS/ALI.

Geriatric care in the surgical intensive care unit

We describe the physiology of aging and its effect on elderly, critically ill, surgical patients. Postoperative age-specific complications and their management will be reviewed. The number of elderly persons, defined as those >65 yrs of age, is the fastest growing segment of the U.S. population. As a result, the frequency of surgery, both elective and emergent, performed on elderly patients will increase. Aging is associated with a decrease in the physiologic reserve; thus, many elderly persons are unable to compensate for the increased metabolic demands that accompany acute illness or injury. This inability to compensate leads to increased rates of postoperative complications and death. Aggressive, goal-directed management in the surgical intensive care unit is beneficial for the geriatric patient. The management of the elderly, surgical, critical care patient is extremely challenging. Understanding age-related physiologic changes will help guide treatment to maximize outcome and prevent complications.

Age-, sex-, and race-based differences among patients enrolled versus not enrolled in acute lung injury clinical trials

OBJECTIVE

Little is known about the participation of racial/ethnic minorities, women, and the elderly into critical care clinical trials. We sought to characterize the representation of racial and ethnic minorities, women, and older patients in clinical trials of patients with acute lung injury and to determine the reasons for nonenrollment.

DESIGN, SETTING, AND PATIENTS

We performed a cross-sectional analysis of pooled screening logs from 44 academic hospitals participating in three multicentered, randomized, controlled trials conducted by the Acute Respiratory Distress Syndrome Network from 1996 to 2005.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We calculated odds ratios of enrollment for age, sex, racial groups, and the odds ratio for the presence of each exclusion criterion by age, sex, and race adjusted for demographics, acute lung injury risk factor, study, and study center. A total of 10.4% of 17,459 screened patients with acute lung injury were enrolled. The median (range) enrollment by center was 15% (2% to 88%). Older patients of both sexes were less likely to be enrolled, but older women were more likely to be enrolled than older men. The adjusted odds ratio (95% confidence interval) for enrollment among men > or =75 yrs of age was 0.59 (0.45 to 0.77) and for women > or =75 yrs of age was 0.45 (0.32 to 0.62) compared with men <35 yrs of age. There were no differences in the likelihood of enrollment among all racial/ethnic groups. Older patients and men were less likely to be enrolled because of medical comorbidity. Among all patients who were not enrolled, black patients and their families refused participation more often than white patients.

CONCLUSIONS

Older patients are less likely to be enrolled in acute lung injury clinical trials. There is no evidence that women or racial/ethnic minorities are underrepresented in acute lung injury clinical trials.

Use of intensive care, mechanical ventilation, both, or neither by patients with acute lung injury

OBJECTIVE

Reports of acute lung injury and acute respiratory distress syndrome have generally been restricted to mechanically ventilated intensive care unit patients, creating an incomplete picture of the epidemiologies of the syndromes. We sought to determine the incidence and outcomes of acute lung injury and acute respiratory distress syndromes throughout an entire hospital population.

DESIGN

Retrospective cohort study.

SETTING

A Department of Veterans Affairs medical center.

PATIENTS

All patients satisfying criteria for acute lung injury or acute respiratory distress syndrome during a 2-yr period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 11,465 acute medical and surgical admissions during the study period; 156 patients had acute lung injury or acute respiratory distress syndrome. Only 74 (47%) were invasively ventilated in an intensive care unit for acute lung injury. Another 15 (10%) patients were ventilated for other reasons, 41 (26%) were admitted to an intensive care unit at approximately the time of acute lung injury onset but were not invasively ventilated, and 26 (17%) were managed with neither invasive ventilation nor admission to an intensive care unit. Four-week mortality differed by group (p = .023), ranging from 22% among those managed in an intensive care unit without invasive ventilation to 50% among those ventilated for acute lung injury or acute respiratory distress syndrome. By 2 yrs, differences in survival between groups were no longer significant. Notably, only 53 (34%) patients would have been eligible for widely cited acute lung injury intervention trials. Ten patients had a second episode of acute lung injury during the study period, equating to a 16%-per-year risk of recurrence.

CONCLUSIONS

Acute lung injury and acute respiratory distress syndrome studies restricted to patients mechanically ventilated in intensive care units substantially underestimate the incidence of the syndromes. Nonventilated patients and those cared for outside of intensive care units may still be at substantial risk for death. Further characterization of previously overlooked acute lung injury and acute respiratory distress syndrome patients may suggest new therapeutic opportunities.

Lower incidence of acute respiratory distress syndrome in community-acquired pneumonia patients aged 85 years or older

Clinical variables and laboratory data were compared to elucidate the risk factors associated with the development of ARDS among elderly patients with community-acquired pneumonia (CAP). The predictors for ARDS appeared to differ from the determinants of severity of CAP. ARDS developed less frequently among patients aged>or=85 years.

BACKGROUND AND OBJECTIVE

The incidence of and risk factors for ARDS among elderly patients with community-acquired pneumonia (CAP) have not been well characterized.

METHODS

The clinical details of 221 consecutive patients aged>or=65 years, who were admitted with CAP during the period April 2006 to June 2008, were investigated by review of patient charts. Clinical variables and laboratory data at admission for CAP were compared between patients with and without ARDS.

RESULTS

Eighteen patients (8.1%) developed ARDS 1-5 days after admission. The mortality rate was 44% in patients with ARDS and 10.3% in those without ARDS (P<0.001). The incidence of ARDS was 8.5-20% among patients aged<85 years and 1.1% in patients aged>or=85 years (P<0.001), while overall mortality rates were not significantly different among the age groups. Predictors for the development of ARDS included higher serum levels of CRP and glucose, lower PaO2/fraction of inspired O2 (FiO2), PaCO2 and HCO3-, and the presence of systemic inflammatory response syndrome at admission. ARDS developed less frequently among patients with pneumonia associated with oropharyngeal aspiration (AP). Multivariate analysis indicated that lower age, serum glucose, pre-existence of systemic inflammatory response syndrome and non-oropharyngeal AP were significant risk factors for ARDS. The Pneumonia Severity Index and confusion, urea, respiratory rate, blood pressure, age>or=65 score were not correlated with the incidence of ARDS.

CONCLUSIONS

Predictors for ARDS appeared to differ from the determinants of severity of CAP in the elderly. ARDS developed less frequently in patients aged>or=85 years and in those with oropharyngeal AP. It is important to identify subjects at high risk for ARDS upon admission and to observe them closely.

A prognostic model for one-year mortality in patients requiring prolonged mechanical ventilation

OBJECTIVE

A measure that identifies patients who are at high risk of mortality after prolonged ventilation will help physicians communicate prognoses to patients or surrogate decision makers. Our objective was to develop and validate a prognostic model for 1-yr mortality in patients ventilated for 21 days or more.

DESIGN

The authors conducted a prospective cohort study.

SETTING

The study took place at a university-based tertiary care hospital.

PATIENTS

Three hundred consecutive medical, surgical, and trauma patients requiring mechanical ventilation for at least 21 days were prospectively enrolled.

MEASUREMENTS AND MAIN RESULTS

Predictive variables were measured on day 21 of ventilation for the first 200 patients and entered into logistic regression models with 1-yr and 3-mo mortality as outcomes. Final models were validated using data from 100 subsequent patients. One-year mortality was 51% in the development set and 58% in the validation set. Independent predictors of mortality included requirement for vasopressors, hemodialysis, platelet count < or = 150 x 10(9)/L, and age > or = 50 yrs. Areas under the receiver operating characteristic curve for the development model and validation model were .82 (SE .03) and .82 (SE .05), respectively. The model had sensitivity of .42 (SE .12) and specificity of .99 (SE .01) for identifying patients who had > or = 90% risk of death at 1 yr. Observed mortality was highly consistent with both 3- and 12-mo predicted mortality. These four predictive variables can be used in a simple prognostic score that clearly identifies low-risk patients (no risk factors, 15% mortality) and high-risk patients (three or four risk factors, 97% mortality).

CONCLUSIONS

Simple clinical variables measured on day 21 of mechanical ventilation can identify patients at highest and lowest risk of death from prolonged ventilation.

An age-associated increase in pulmonary inflammation after burn injury is abrogated by CXCR2 inhibition

Burn patients over the age of 60 are at a greater risk for developing pulmonary complications than younger patients. The mechanisms for this, however, have yet to be elucidated. The objective of this study was to determine whether increased chemoattraction plays a role in the age-related differences in pulmonary inflammation after burn injury. At 6 or 24 h after receiving sham or 15% total body surface area scald injury, lungs from young and aged mice were analyzed for leukocyte content by histological examination and immunostaining. Lungs were then homogenized, and levels of neutrophil chemokines, MIP-2 and KC, were measured. At 6 h after burn, the number of neutrophils was four times higher in the lungs of both burn groups compared with aged-matched controls (P<0.05), but no age difference was evident. At 24 h, in contrast, neutrophils returned to sham levels in the lungs of young, burn-injured mice (P<0.05) but did not change in the lungs of aged, burn-injured mice. Pulmonary levels of the neutrophil chemokine KC but not MIP-2 were consistently three times higher in aged, burn-injured mice compared with young, burn-injured mice at both time-points analyzed. Administration with anti-CXCR2 antibody completely abrogated the excessive pulmonary neutrophil content by 24 h (P<0.05), while not affecting the inflammatory response of the wounds. These studies show that CXCR2-mediated chemoattraction is involved in the pulmonary inflammatory response after burn and suggest that aged individuals sustaining a burn injury may benefit from treatment strategies that target neutrophil chemokines.

A transgenic mouse with vascular endothelial over-expression of the non-muscle myosin light chain kinase-2 isoform is susceptible to inflammatory lung injury: role of sexual dimorphism and age

We have generated genetically engineered mice that are uniquely susceptible to lipopolysaccharide (LPS)-induced and mechanical ventilation-induced lung injury in a sex-specific and age-specific manner. These mice express a nonmuscle isoform of the myosin light chain kinase gene (nmMLCK2) targeted to the endothelium. Homozygous mice have significantly reduced fecundity and litter survival until weaning, and they are initially growth delayed but eventually exceed the size of wild-type littermates. Mice at all ages show increased protein transport across the lung barrier; however, the phenotype is most discernible in 8-12-week-old male mice. When subjected to a clinically relevant LPS-induced lung injury model, 8-12-week-old young females and 30-36-week-old males seem to be the most significantly injured group. In contrast, 30-36-week-old males remain the most significantly injured group when mechanically ventilated at high tidal volumes, which is a clinically relevant model of mechanical stress lung injury. These data reveal that nmMLCK2 overexpression in the endothelium exacerbates lung injury in vivo in a sexually dimorphic and age-dependent manner.

Predictors of mortality in ARDS patients referred to a tertiary care centre: a pilot study

BACKGROUND AND OBJECTIVE

In order to identify parameters predicting intensive care unit mortality in patients transferred to a specialized tertiary centre because of progressive acute respiratory distress syndrome, an observational pilot study was carried out involving 94 patients.

METHODS AND RESULTS

Forty-one patients (43.6%) died. Survival was defined as intensive care unit discharge. Survivors were younger (32.0 +/- 11.8 vs. 39.1 +/- 12.4 yr, P = 0.008), at admission they had a lower acute physiology and chronic health evaluation (APACHE) II score (21.7 +/- 5.4 vs. 25.4 +/- 5.2, P = 0.0009), higher PaO2/FiO2 (122 +/- 79 vs. 79 +/- 42 mmHg, P = 0.002), lower positive end-expiratory pressure (10.6 +/- 3.1 vs. 12.5 +/- 3.7 cmH2O, P = 0.02) and a lower Murray score (2.8 +/- 0.63 vs. 3.0 +/- 0.62, P = 0.04). No differences were observed for tidal volumes and peak inspiratory pressures. Days of hospitalization and mechanical ventilation prior to transferral were not related to survival. Multivariate analysis of variables assessed on admission detected only differences for age (P = 0.014) and APACHE II (P = 0.005). Odds ratio was 1.06 (95% confidence interval (CI): 1.013-1.119) for age and 1.21 (CI: 1.059-1.381) for APACHE II. Multivariate analysis of changes in respiratory parameters, APACHE II and Murray score during the first 3 days after transferral revealed a significant difference only for positive end-expiratory pressure (P < 0.008). Corresponding odds ratio was 2.40 (CI: 1.25-4.58) for an increase of 1 cmH2O/24 h.

CONCLUSION

Age-related mortality in this small, but highly selected group of patients with established ARDS increased early in life even in a population with an overall mean age of 35.1 yr. APACHE II was the only clinical predictor for mortality on admission. The need for a substantial increase in positive end-expiratory pressure after transferral markedly reduced the chance to survive.

Clinical characteristics and prognostic factors in patients with complicated acute coronary syndromes requiring prolonged mechanical ventilation

Patients with acute coronary syndromes (ACSs) may develop serious multiorgan complications and require prolonged intensive care. Our aim was to characterize and identify factors that are associated with outcomes in these patients. We retrospectively identified 267 consecutive patients admitted to the coronary care unit for an ACS who required >3 days of mechanical ventilation. Multiple clinical and laboratory variables were correlated with mortality. Patients' ages were 68.3 +/- 10.9 years (mean +/- SD) and 165 (62%) were men. Seventy-six patients (29%) died within 30 days of admission, and the 1 year mortality was 46%. Moderate or severe left ventricular systolic dysfunction was found in 72% of the patients. Eighty-nine patients (33.3%) required vasopressors, of whom 64 (72%) did not survive 30 days. Among 127 patients who required antibiotics (48.3%), 30-day mortality was 53% compared with 4% among patients who did not require antibiotics (p <0.001). The 30-day mortality among patients who received both antibiotics and vasopressors was 64 of 87 patients (74%), and the 1-year mortality in this subgroup was 86.2%. Parameters found to be independent predictors of 30-day mortality were (in descending order): vasopressor requirement, use of antibiotics, peripheral vascular disease, ST-elevation myocardial infarction, renal failure, obesity and Killip class on admission. In conclusion, mortality among patients who require prolonged mechanical ventilation after an ACS is substantial. The main independent predictors of with mortality are the severity of heart failure and the presence of co-morbidities.

Causes and timing of death in patients with ARDS

BACKGROUND

Since the early 1980s, case fatality of patients with ARDS has decreased, and explanations are unclear.

DESIGN AND METHODS

Using identical definitions of ARDS and organ failure, we analyzed consecutive cohorts of patients meeting syndrome criteria at our institution in 1982 (n = 46), 1990 (n = 112), 1994 (n = 99), and 1998 (n = 205) to determine causes and timing of death.

RESULTS

Overall case fatality has decreased from 68% in 1981-1982 to a low of 29% in 1996, plateauing since the mid-1990s (p = 0.001 for trend). Sepsis syndrome with multiple organ failure remains the most common cause of death (30 to 50%), while respiratory failure causes a small percentage (13 to 19%) of deaths. The distribution of causes of death has not changed over time. There was no change in the timing of death during the study periods: 26 to 44% of deaths occurred early (< 72 h after ARDS onset), and 56 to 74% occurred late (> 72 h after ARDS onset). However, the increased survival over the past 2 decades is entirely accounted for by patients who present with trauma and other risk factors for their ARDS, while survival for those patients whose risk factor is sepsis has not changed. Additionally, withdrawal of life support in these patients is now occurring at our institution significantly more frequently than in the past, and median time until death has decreased in patients who have support withdrawn.

CONCLUSIONS

While these results do not explain the overall case fatality decline in ARDS, they do indicate that sepsis syndrome remains the leading cause of death and suggest that future therapies to improve survival be targeted at reducing the complications of sepsis.

Elevated plasma and lung endothelial selectin levels in patients with acute respiratory distress syndrome and a history of chronic alcohol abuse

OBJECTIVE

Activation of endothelial cells is a critical step in the pathogenesis of acute respiratory distress syndrome (ARDS). Soluble endothelial selectin (sE-selectin), an endothelial cell-specific molecule that mediates leukocyte-endothelial cell adhesion has never been measured in the bronchoalveolar lavage fluid of critically ill patients. Based on the effects of alcohol on endothelial cell and alveolar-capillary barrier function, we hypothesized that chronic alcohol exposure may be associated with increased sE-selectin in ARDS patients.

DESIGN

Prospective observational cohort study.

SETTING

Medical and surgical intensive care units; an inpatient alcohol detoxification unit within university-affiliated hospitals.

PATIENTS

A total of 20 ARDS patients (50% with chronic alcohol abuse); seven individuals with a history of chronic alcohol abuse.

INTERVENTION

Patients underwent bronchoalveolar lavage within 72 hrs of ARDS diagnosis. Individuals with a history of chronic alcohol abuse underwent bronchoalveolar lavage within 7 days of their last alcoholic beverage. A history of chronic alcohol abuse was determined by a Short Michigan Alcohol Screening Test score of > or =3 or a history of an alcohol-related diagnosis. sE-selectin was measured in plasma and bronchoalveolar lavage.

MEASUREMENTS AND MAIN RESULTS

Neither severity of illness nor at-risk diagnosis differed by alcohol history. sE-selectin levels in the plasma of ARDS patients who abused alcohol chronically were significantly elevated compared with nonalcoholic ARDS patients (181 ng/mL [56-328] vs. 32 ng/mL [14-55], p <.01). The bronchoalveolar lavage sE-selectin levels from the patients with ARDS and alcohol abuse were also significantly elevated compared with nonalcoholic ARDS patients (1.51 ng/mL [1.09-3.11] vs. 0.69 ng/mL [0.33-0.94], p <.002) and were higher than those measured in individuals with a history of chronic alcohol abuse but without ARDS (0.46 ng/mL [0.12-2.75], p =.15).

CONCLUSIONS

ARDS patients who chronically abuse alcohol have elevated concentrations of sE-selectin in both the plasma and epithelial lining fluid consistent with altered endothelial cell and alveolar-capillary barrier function.

[Long term of quality of life and mortality in acute respiratory distress syndrome (ARDS) patients]

INTRODUCTION

Although advanced technology and make many researches, the acute respiratory distress syndrome has been associated to high mortality. We prospectively evaluated the quality of life and mortality changes in patients with acute respiratory distress syndrome, was used quality of life indicators, as well as we determinated if positional strategie will be have an influence to falling-off in mortality.

MATERIAL AND METHODS

We combined the Karnosfky scale, daily live activities index, and the perception of quality of life scale to assess previously quality of life before admission to the intensive care unit and 6 moths after realese for 59 patients with acute respiratory distress syndrome. Mortality was compared with age, stay, severity of disease, nine equivalent manpower score and quality of life indicators. We evaluated mortality according to position strategie supine-position or pron-position.

RESULTS

Mortality was to the 57%. Three significant variables related with mortality were identified: age, nine equivalent manpower score and quality of life indicators. We didn't find any significant differentiate between positioning strategies. All of quality of life indicators were decrease six months after discharge to the intensive care unit.

DISCUSSION

Mortality from patients acute respiratory distress syndrome is described between ratio for others authors, as well as it doesn't condittioned for positional estrategie used. The quality of life of survivors have deteriorated moderately, it was attributable to chronic disease.

Outcomes and Costs Among Seniors Requiring Hospitalization for Community-Acquired Pneumonia in Alberta

OBJECTIVES

To determine the age-specific rates of hospital discharge, cost per day, and overall in-hospital 1- and 4-year mortality for seniors who required hospitalization for the treatment of community-acquired pneumonia (CAP).

DESIGN

Retrospective analysis of two administrative health service databases.

SETTING

Province of Alberta, Canada.

PARTICIPANTS

Residents of Alberta aged 18 and older.

MEASUREMENTS

Hospital abstracts and vital statistics from April 1, 1994, to March 31, 1999, were analyzed, and mortality and cost outcomes statistically modeled by regression.

RESULTS

There were 8,500 annual hospital discharges for CAP costing more than $40 million per year. The overall in-hospital all-cause mortality rate was 12%, and the 1-year mortality rate was 26%. The mean age of pneumonia cases increased (P<.000) from 62.8 in 1994/1995 to 67.2 in 1998/1999. The proportion of hospital discharges in those aged 85 and older was 13% in 1994/1995, increasing to 18% in 1998/1999 (P<.000). The age-specific hospital discharge rate and length of hospitalization increased with age. After adjustment for other factors using modeling, it was found that the relative risk (RR) of in-hospital and 1-year mortality increased with age, the RR of using special medical care and higher-than-average daily hospital cost decreased with age, and the RR of greater-than-average daily hospital cost was not associated with an increase in comorbidity. Total costs per hospital stay were similar in patients aged 85 and older to those in patients aged 65 to 74, despite a one-third longer length of stay, which was consistent with reduced use of special medical care in those aged 85 and older.

CONCLUSION

The increased use of hospital resources for CAP in the setting of an aging population may have been partially avoided because of limitations in care provided for seniors aged 85 and older.

The epidemiology of critical illness in the elderly

A substantial proportion of patients admitted to intensive care units (ICUs) are elderly patients. Based upon population growth, patient preference, and current physician practice, the number of elderly patients who receive critical care services is likely to increase substantially over the next 10 to 20 years. Numerous studies have shown that survival from critical illness is lower in elderly patients; however, after adjusting for factors such as illness severity, comorbid diseases, and functional status, chronologic age accounts for very little explanatory power for survival from critical illness. Elderly survivors of critical illness often have significant functional limitations, but their perceived quality of life is usually better than that of younger survivors of critical illness. Elderly patients frequently receive less aggressive care in the ICU and probably consume a lower relative proportion of ICU resources than younger patients. However, this does not necessarily result in worse outcomes.

Quality of life in acute respiratory distress syndrome survivors may be no worst than in other ICU survivors

OBJECTIVE

To compare the health-related quality of life (HR-QOL) in acute respiratory distress syndrome (ARDS) survivors with that in a matched control group of non-ARDS survivors.

DESIGN AND SETTING

Prospective, matched, parallel cohort study, comparing HR-QOL between intensive care unit (ICU) survivors with ARDS and a control group in a tertiary care hospital.

PATIENTS

Between May 1997 and December 2000, all ARDS adult patients of an eight-bed medical/surgical unit of a tertiary care hospital were enrolled and a control group of non-ARDS survivors, matched for severity of disease and for previous health state, was selected. The study included 29 ARDS survivors who answered the EQ-5D questionnaire and had lung function evaluated.

MEASUREMENTS AND RESULTS

A follow-up appointment was performed 6 months after ICU discharge consisting of: (a) evaluation of HR-QOL using EQ-5D and (b) lung function tests and measure of diffusing capacity. Among ARDS survivors 41% had normal lung function and 59% mild to moderate lung function impairments. Nearly a one-third of ARDS survivors reported problems in one or more of the five dimensions of the EQ-5D, and 48% reported feeling worse at the interview than 6 month before ICU admission. No significant differences were found in HR-QOL between ARDS survivors and other ICU survivors with similar age and matched for previous health state and severity of disease.

CONCLUSIONS

This study suggests that impairments in HR-QOL among ARDS survivors may not be distinguishable from that among other ICU survivors.

Acute lung injury and the acute respiratory distress syndrome

Although ALI/ARDS mortality rates have improved over the last several decades, they remain high, particularly in the geriatric patient population. Although considerable progress has been made in understanding the pathogenesis of the disease, a large number of promising treatments have proven unsuccessful. One exception has been in the area of ventilator management, where a strategy of protective ventilation with low tidal volumes has demonstrated a significant mortality benefit. Basic research continues to help advance our understanding of this complex syndrome and identify interesting new directions of investigation. The results of several large, randomized trials of new ventilatory and pharmacologic strategies currently underway may help identify successful methods of treating this important disease.

Epidemiology and outcome of acute respiratory failure in intensive care unit patients

OBJECTIVES

To summarize the prevalence of various forms of acute respiratory failure in acutely ill patients and review the major factors involved in the outcome of these patients.

DATA SOURCES AND SELECTION

MEDLINE search for published studies reporting the prevalence or outcome for patients with acute respiratory failure and cited reference studies and abstracts from a recent international meeting in the intensive care medicine field.

DATA SYNTHESIS AND EXTRACTION

From the selected articles, information was obtained regarding the prevalence of acute respiratory failure, including acute respiratory distress syndrome and acute lung injury as defined by the North American-European Consensus Conference, the outcome, and the factors influencing mortality rates in this population of patients.

CONCLUSIONS

The prevalence of acute respiratory failure varies according to the definition used and the population studied. Nonsurvivors of acute respiratory distress syndrome die predominantly of respiratory failure in <20% of cases. The relatively high mortality rates of acute lung injury/acute respiratory distress syndrome are primarily related to the underlying disease, the severity of the acute illness, and the degree of organ dysfunction.

Respiratory failure in elderly patients

Elderly individuals comprise an increasing proportion of the population and represent a progressively expanding number of patients admitted to the ICU. Because of underlying pulmonary disease, loss of muscle mass, and other comorbid conditions, older persons are at increased risk of developing respiratory failure. Recognition of this vulnerability and the adoption of proactive measures to prevent decompensation requiring intrusive support are major priorities together with clear delineation of patients' wishes regarding the extent of support desired should clinical deterioration occur. Further, the development of coordinated approaches to identify patients at risk for respiratory failure and strategies to prevent the need for intubation, such as the use of NIV in appropriate patients, are crucial. As soon as endotracheal intubation and mechanical ventilation are implemented strategies that facilitate the liberation of elderly patients from the ventilator are especially important. The emphasis on a team approach, which characterizes geriatric medicine, is essential in coordinating the skills of multiple health care professionals in this setting. Respiratory failure can neither be effectively diagnosed nor managed in isolation. Integration with all other aspects of care is essential. Patient vulnerability to nosocomial complications and the "cascade effect" of these problems such as the effects of medications and invasive supportive procedures all impact on respiratory care of elderly patients. For example, prolonged mechanical ventilation may be required long after resolution of the underlying cause of respiratory failure because of unrecognized and untreated delirium or residual effects of small doses of sedative and/or analgesic agents or other medications in elderly patients with altered drug metabolism. The deleterious impact of the foreign and sometimes threatening ICU environment and/or sleep deprivation on the patient's course are too often overlooked because the physician focuses management on physiologic measurements, mechanical ventilator settings, and other technologic nuances of care [40]. Review of the literature suggests that the development of respiratory failure in patients with certain disease processes such as COPD, IPF, and ARDS in elderly patients may lead to worsened outcome but it appears that the disease process itself, rather than the age of the patient, is the major determinant of outcome. Additional studies suggest that other comorbid factors may be more important than age. Only when comorbid processes are taken into account should decisions be made about the efficacy of instituting mechanical ventilation. In addition, because outcome prediction appears to be more accurate for groups of patients rather than for individual patients a well-structured therapeutic trial of instituting mechanical ventilation, even if comorbidities are present, may be indicated in certain patients if appropriately informed patients wish to pursue this course. This approach requires careful and realistic definition of potential outcomes, focus on optimizing treatment of the reversible components of the illness, and continuous communication with the patient and family. Although many clinicians share a nihilistic view regarding the potential usefulness of mechanical ventilation in elderly patients few data warrant this negative prognostication and more outcome studies are needed to delineate the optimum application of this element of supportive care. As with other interventions individualization of the decision must take into account the patient's premorbid status, concomitant conditions, the nature of the precipitating illness and its prospects for improvement, and most important, patient preferences. In this determination pursuing the course most consistent with the patient's wishes is essential and it must be appreciated that caregivers' impressions regarding the vigor of support desired by the patient are often erroneous. The SUPPORT investigators observed that clinicians often underestimated the degree of intervention desired by older patients assuming that less care would be desired [13]. Thus, as in other circumstances, effective communication and elicitation of patients' preferences regarding management options is crucial in the management of respiratory failure. The frequent discordance between patient preferences and the wishes of family members or other surrogate decision makers impose major clinical challenges and also mandates further investigation.

Acute respiratory distress syndrome epidemiology and pathophysiology

Acute respiratory distress syndrome is a devastating syndrome of lung injury following known risk factors, with a persistently high mortality. A consensus conference definition of ARDS has been adopted by clinical researchers, but potential problems remain. ARDS may represent more than one entity, and radiographic and mechanical differences between pulmonary versus extrapulmonary initiated ARDS have been described. There is increasing recognition of inflammatory mediators in the pathophysiology of acute lung injury. Surfactant abnormalities contribute to the associated lung dysfunction. A growing body of evidence supports the presence of VILI and a potential mechanism for developing MOSF, and has led to new management strategies. The importances of apoptosis to the repair process, and mechanisms that may lead to persistent fibrosis, such as the activation of the coagulant pathway with fibrin deposition, are increasingly recognized.

The epidemiology of acute respiratory failure in critically ill patients(*)

STUDY OBJECTIVES

To describe the risk factors for the development of and mortality resulting from acute respiratory failure (ARF) in a large patient population.

DESIGN

A substudy of a prospective, multicenter, observational cohort study, which was designed to validate the sequential organ failure assessment score.

SETTING

Forty ICUs in 16 countries.

PATIENTS

All critically ill patients who were admitted to one of the participating ICUs during a 1-month period were observed until the end of their hospital course.

MEASUREMENTS AND RESULTS

Of the 1,449 patients who were enrolled into the study, 458 (32%) were admitted to an ICU with ARF, as defined by a PaO(2)/fraction of inspired oxygen ratio of < 200 mm Hg and the need for respiratory support. Patients who presented with ARF were older than the other patients (63 vs 57 years, respectively; p < 0.001) and more commonly had an infection (47% vs 20%, respectively; p < 0.001). The length of ICU stay was longer (6 vs 4 days, respectively; p < 0.001) and the ICU mortality rate was more than double (34% vs 16%, respectively; p < 0.001) in ARF patients compared to non-ARF patients. Of the 991 patients who were admitted to an ICU without ARF, 352 (35%) developed ARF later during the ICU stay. The independent risk factors for the development of ARF were infection developing in the ICU (odds ratio [OR], 7.59; 95% confidence interval [CI], 5.08 to 11.33) or present on ICU admission (OR, 2.3; 95% CI, 1.68 to 3.16), the presence of neurologic failure on ICU admission (OR, 2.73; 95% CI, 1.90 to 3.91), and older age (OR, 1.70; 95% CI, 1.30 to 2.22). Of all 810 patients with ARF, 253 (31%) died. The independent risk factors for death were multiple organ failure following ICU admission, history of hematologic malignancy, chronic renal failure or liver cirrhosis, the presence of circulatory shock on ICU admission, the presence of infection, and older age.

CONCLUSIONS

The present study stresses that ARF is common in the ICU (56% of all patients) and that a number of extrapulmonary factors are related to the risk of development of ARF and to mortality rate in these patients.

Prospective, randomized, controlled pilot study of partial liquid ventilation in adult acute respiratory distress syndrome

We evaluated the safety and efficacy of partial liquid ventilation (PLV) with perflubron in adult patients with acute lung injury and the acute respiratory distress syndrome (ARDS) in a multicenter, prospective, controlled, randomized exploratory clinical trial. Ninety adult patients with PaO2/FIO2 ratios > 60 and < 300 with ARDS for no more than 24 hours were randomized to receive PLV (n = 65) with administration of perflubron through an endotracheal tube sideport or conventional mechanical ventilation (CMV, n = 25) for a maximum of five days. Although a significant reduction in progression to ARDS was noted among patients with PLV, no significant differences in the number of days free from the ventilator at 28 days (CMV = 6.7 +/- 1.8, PLV = 6.3 +/- 1.0 days, p = 0.85), the incidence of mortality (CMV = 36%, PLV = 42%, p = 0.63), or any pulmonary-related parameter were observed. During a post hoc subgroup analysis, significantly more rapid discontinuation of mechanical ventilation (p = 0.045) and a trend toward an increase in the number of days free from the ventilator at 28 days (CMV = 3.2 +/- 1.9, PLV = 8.0 +/- 2.2 days, p = 0.06) were observed during PLV among those patients under 55 years of age with acute lung injury or ARDS. Episodes of hypoxia, respiratory acidosis, and bradycardia occurred more frequently in the PLV group, but these were transient and self-limited. Further evaluation of PLV is warranted to further define beneficial effects in well-defined groups of patients and also to gain additional information regarding safety.