Fibroproliferative phase of ARDS. Clinical findings and effects of corticosteroids

Fever in the ICU

Fever is a common problem in ICU patients. The presence of fever frequently results in the performance of diagnostic tests and procedures that significantly increase medical costs and expose the patient to unnecessary invasive diagnostic procedures and the inappropriate use of antibiotics. ICU patients frequently have multiple infectious and noninfectious causes of fever, necessitating a systematic and comprehensive diagnostic approach. Pneumonia, sinusitis, and blood stream infection are the most common infectious causes of fever. The urinary tract is unimportant in most ICU patients as a primary source of infection. Fever is a basic evolutionary response to infection, is an important host defense mechanism and, in the majority of patients, does not require treatment in itself. This article reviews the common infectious and noninfectious causes of fever in ICU patients and outlines a rational approach to the management of this problem.

Hepatocyte growth factor is elevated in chronic lung injury and inhibits surfactant metabolism

Adult respiratory distress syndrome may incorporate in its pathogenesis the hyperplastic proliferation of alveolar epithelial type II cells and derangement in synthesis of pulmonary surfactant. Previous studies have demonstrated that hepatocyte growth factor (HGF) in the presence of serum is a potential mitogen for adult type II cells (R. J. Panos, J. S. Rubin, S. A. Aaronson, and R. J. Mason. J. Clin. Invest. 92: 969-977, 1993) and that it is produced by fetal mesenchymal lung cells (J. S. Rubin, A. M.-L. Chan, D. P. Botarro, W. H. Burgess, W. G. Taylor, A. C. Cech, D. W. Hirschfield, J. Wong, T. Miki, P. W. Finch, and S. A. Aaronson. Proc. Natl. Acad. Sci. USA 88: 415-419, 1991). In these studies, we expand on this possible involvement of HGF in chronic lung injury by showing the following. First, normal adult lung fibroblasts transcribe only small amounts of HGF mRNA, but the steady-state levels of this message rise substantially in lung fibroblasts obtained from animals exposed to oxidative stress. Second, inflammatory cytokines produced early in the injury stimulate the transcription of HGF in isolated fibroblasts, providing a plausible mechanism for the increased amounts of HGF seen in vivo. Third, HGF is capable of significantly inhibiting the synthesis and secretion of the phosphatidylcholines of pulmonary surfactant. Fourth, HGF inhibits the rate-limiting enzyme in de novo phosphatidylcholine synthesis, CTP:choline-phosphate cytidylyltransferase (EC 2.7.7.15). Our data indicate that fibroblast-derived HGF could be partially responsible for the changes in surfactant dysfunction seen in adult respiratory distress syndrome, including the decreases seen in surfactant phosphatidylcholines.

Evolution of leukotriene B4, peptide leukotrienes, and interleukin-8 plasma concentrations in patients at risk of acute respiratory distress syndrome and with acute respiratory distress syndrome: mortality prognostic study

OBJECTIVE

To compare the evolution of plasma concentrations of leukotriene (LT) B4, LTC4, LTD4, and interleukin (IL)-8 in patients with acute respiratory distress syndrome (ARDS) and in patients at risk of ARDS and to assess the value of these mediators in predicting mortality rate from ARDS.

DESIGN

A case-control study comparing ARDS patients and patients at risk of ARDS as well as survivors and nonsurvivors with ARDS.

SETTING

Hospital intensive care unit, laboratory, and department of hematology.

PATIENTS

Twenty-one patients with ARDS and 14 patients at risk of ARDS.

INTERVENTION

Arterial blood samples were collected on days 0, 1, and 5 after admission to the intensive care unit.

MEASUREMENTS AND MAIN RESULTS

LTs were extracted, separated by high-pressure liquid chromatography and quantified by enzyme immunoassay. IL-8 was analyzed by ELISA. Plasma concentrations of LTB4 and LTC4 plus LTD4 were significantly higher in ARDS patients than in patients at risk of ARDS during the first 24 hrs. Concentrations of IL-8 were also higher in ARDS patients than in patients at risk throughout the study, although the differences between the two groups were only significant on day 5. Only the plasma concentration of LTB4 on day 1 was a marker of ARDS (72.2% sensitivity, 84.6% specificity). A logistic regression analysis showed that LTB4 and IL-8, on day 1, were markers of mortality rate in patients with ARDS (70.0% sensitivity, 87.5% specificity).

CONCLUSIONS

LTs are elevated during the early phases of ARDS, whereas IL-8 increases throughout the study. The evaluation of LTB4 and IL-8 may be useful prognostic indices in patients with early phase ARDS after admission to the intensive care unit.

Discrimination of infectious and noninfectious causes of early acute respiratory distress syndrome by procalcitonin

OBJECTIVE

To test the sepsis marker procalcitonin (PCT) for its applicability to discriminate between septic and nonseptic causes of acute respiratory distress syndrome (ARDS).

DESIGN

Prospective study, assessing the course of PCT serum levels in early (within 72 hrs after onset) ARDS. The three other inflammation markers neopterin, interleukin-6 (IL-6), and C-reactive protein (CRP) were tested in parallel.

SETTING

Twenty-four-bed medical intensive care unit of a 1,990-bed primary hospital, providing health care for an estimated 39,000 patients.

PATIENTS

Twenty-seven patients, 18 male and nine female, aged 16-85 yrs, with early ARDS of known cause (17 with septic and ten with nonseptic ARDS) were enrolled in a prospective study between May 1994 and May 1995.

INTERVENTIONS

Serum samples were drawn every 4-6 hrs for measurement of PCT, neopterin, IL-6, and CRP concentrations. Blood cultures, tracheal aspirates, and urine samples were obtained every 12-24 hrs. In 24 of 27 patients, bronchoscopic cultures were also obtained. Clinical sepsis criteria as defined by the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference were checked daily.

MEASUREMENTS AND MAIN RESULTS

Assessment of inflammation marker serum levels in septic vs. nonseptic ARDS. PCT serum levels were significantly higher (p < .0005) in the patients with septic ARDS than in patients with nonseptic ARDS within 72 hrs after onset of ARDS. There was no overlap between the two groups. Also, neopterin allowed a differentiation (p < .005), although a substantial overlap between serum levels of septic and nonseptic patients was observed. No discrimination could be achieved by determination of CRP and IL-6 levels.

CONCLUSION

PCT determination in early ARDS could help to discriminate between septic and nonseptic underlying disease.

Clinical diagnosis of ventilator associated pneumonia revisited: comparative validation using immediate post-mortem lung biopsies

BACKGROUND

A study was undertaken to assess the diagnostic value of different clinical criteria and the impact of microbiological testing on the accuracy of clinical diagnosis of suspected ventilator associated pneumonia (VAP).

METHODS

Twenty five deceased mechanically ventilated patients were studied prospectively. Immediately after death, multiple bilateral lung biopsy specimens (16 specimens/patient) were obtained for histological examination and quantitative lung cultures. The presence of both histological pneumonia and positive lung cultures was used as a reference test.

RESULTS

The presence of infiltrates on the chest radiograph and two of three clinical criteria (leucocytosis, purulent secretions, fever) had a sensitivity of 69% and a specificity of 75%; the corresponding numbers for the clinical pulmonary infection score (CPIS) were 77% and 42%. Non-invasive as well as invasive sampling techniques had comparable values. The combination of all techniques achieved a sensitivity of 85% and a specificity of 50%, and these values remained virtually unchanged despite the presence of previous treatment with antibiotics. When microbiological results were added to clinical criteria, adequate diagnoses originating from microbiological results which might have corrected false positive and false negative clinical judgements (n = 5) were countered by a similar proportion of inadequate diagnoses (n = 6).

CONCLUSIONS

Clinical criteria had reasonable diagnostic values. CPIS was not superior to conventional clinical criteria. Non-invasive and invasive sampling techniques had diagnostic values comparable to clinical criteria. An algorithm guiding antibiotic treatment exclusively by microbiological results does not increase the overall diagnostic accuracy and carries the risk of undertreatment.

Proliferation, C-myc, and cyclin D1 expression in diffuse alveolar damage: potential roles in pathogenesis and implications for prognosis

In this study we compared expression of DNA topoisomerase IIalpha, a marker of cellular proliferation, c-myc, and cyclin D1 in lung biopsy specimens showing diffuse alveolar damage (DAD) with control lung tissues. We subsequently correlated DNA topoisomerase IIalpha, c-myc, and cyclin D1 expression with survival. We hypothesized that poor outcome may correlate with a higher proliferation index, and that c-myc and cyclin D1 activation are potentially important regulators of both proliferation and apoptosis in DAD. Immnuohistochemical stains for c-myc, cyclin D1, and DNA topoisomerase IIalpha were performed on 10 cases of DAD (15 cases for DNA topoisomerase IIalpha) and 10 control lungs. A proliferation index for each case was calculated by dividing the number of nuclei expressing DNA topoisomerase IIalpha by the total number of nuclei counted. The percentages of alveolar pneumocytes and interstitial cells staining positively for c-myc and cyclin D1 were estimated. The average proliferation index (DNA topoisomerase IIalpha index) in DAD (0.16 +/- 0.06, n = 15) was significantly greater than in control lungs (0.00 +/- 0.01, n = 10) (P < .0001). The average proliferation index of patients with DAD who died of respiratory failure (0.18 +/- 0.05, n = 9) was significantly greater than the average proliferation index of patients whose respiratory disease resolved or stabilized (0.11 +/- 0.05, n = 5) (P < .03). Expression of c-myc in alveolar pneumocytes and interstitial cells was more intense and slightly more widespread in cases of DAD compared with control lungs. In 9 of 10 cases of DAD, cyclin D1 expression was present in up to 30% of alveolar pneumocytes and up to 10% of interstitial cells. No staining for cyclin D1 was present in control lungs. These results show that the proliferation index in DAD potentially correlates with patient survival. Furthermore, enhanced expression of c-myc and cyclin D1 may contribute to dysregulation of cellular proliferation and apoptosis observed in DAD.

Respiratory infectious complications in the intensive care unit

Ventilator-associated pneumonia is the most common infectious respiratory complication in intensive care unit patients, particularly those needing mechanical ventilation. Ventilator-associated pneumonia represents a challenging problem in terms of diagnosis, treatment, and prevention. Nosocomial sinusitis is another respiratory infection, not uncommon in mechanically ventilated patients. This type of infection has to be suspected in nasally intubated patients and may be a hidden focus of fever and sepsis.

The utility of open lung biopsy in patients requiring mechanical ventilation

STUDY OBJECTIVE

To determine the diagnostic yield, morbidity, mortality, and therapeutic impact of the open lung biopsy in patients requiring mechanical ventilation.

DESIGN

Retrospective review of patient records.

SETTING

Tertiary ICU.

PATIENTS

Patients with respiratory failure and diffuse pulmonary infiltrates requiring mechanical ventilation, leading up to or following an open lung biopsy.

MEASUREMENTS

Information included patient demographics, organ failure, microbiological results before open-lung biopsy, Pao,/fraction of inspired oxygen values before and after biopsy, immunosuppression, timing of open lung biopsy, biopsy-related morbidity and mortality, duration of after-biopsy ventilation, open lung biopsy results, biopsy-initiated treatment alterations, and hospital outcome.

RESULTS

Twenty-four patients were identified. The mean age was 48.9 years (confidence interval, 42.1 to 55.7). Twenty-one percent had respiratory infections diagnosed before open lung biopsy but not confirmed by open lung biopsy. Intraoperative complications occurred in 21% of patients, and postoperative complications occurred in 17% of patients. Operative mortality was 8.4%. The specific and the nonspecific diagnostic rates were both 46%. Lung histology was normal in two patients; one of those patients had a false-negative finding. No patient with respiratory failure plus 2 2 other organ failures survived. Alteration of therapy did not differentiate between survivors. Open lung biopsy-guided alteration of therapy directly benefited 39%, and withdrawal was possible in 8.4% of the patients.

CONCLUSIONS

The multiple organ dysfunction score should be considered when deciding the relative risk of performing an open lung biopsy, which in this group of patients provided a specific diagnosis in 46% and carried a mortality rate of 8.4%.

Epidemiology of ventilator-acquired pneumonia based on protected bronchoscopic sampling

We performed a prospective observational cohort study of the epidemiology and etiology of nosocomial pneumonia in 358 medical ICU patients in two university-affiliated hospitals. Protected bronchoscopic techniques (protected specimen brush and bronchoalveolar lavage) were used for diagnosis to minimize misclassification. Risk factors for ventilator-associated pneumonia were identified using multiple logistic regression analysis. Twenty-eight cases of pneumonia occurred in 358 patients for a cumulative incidence of 7.8% and incidence rates of 12.5 cases per 1, 000 patient days and 20.5 cases per 1,000 ventilator days. Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Hemophilus species made up 65% of isolates from the lower respiratory tract, whereas only 12.5% of isolates were enteric gram-negative bacilli. Daily surveillance cultures of the nares, oropharynx, trachea, and stomach demonstrated that tracheal colonization preceded ventilator-associated pneumonia in 93.5%, whereas gastric colonization preceded tracheal colonization for only four of 31 (13%) eventual pathogens. By multiple logistic regression, independent risk factors for ventilator- associated pneumonia were admission serum albumin <= 2.2 g/dl (odds ratio [OR] 5.9; 95% confidence interval [CI] 2.0-17.6; p = 0.0013), maximum positive end-expiratory pressure >= 7.5 cm H2O (OR, 4.6; 95% CI, 1.4 to 15.1; p = 0.012), absence of antibiotic therapy (OR, 6.7; 95% CI, 1.8 to 25.3; p = 0.0054), colonization of the upper respiratory tract by respiratory gram-negative bacilli (OR, 3.4; 95% CI, 1.1 to 10.1; p = 0.028), pack-years of smoking (OR, 2.3 for 50 pack-years; 95% CI, 1. 2 to 4.2; p = 0.012), and duration of mechanical ventilation (OR, 3. 4 for 14 d; 95% CI, 1.5 to 7.8; p = 0.0044). Several of these risk factors for ventilator-associated pneumonia appear amenable to intervention.

Procollagen types I and III aminoterminal propeptide levels during acute respiratory distress syndrome and in response to methylprednisolone treatment

Ineffective lung repair in patients with unresolving acute respiratory distress syndrome (ARDS) is accompanied by progressive fibroproliferation, inability to improve lung injury score (LIS), progressive multiple organ dysfunction syndrome (MODS), and an unfavorable outcome. Our aim was to investigate the relationship between fibrogenesis, pulmonary and extrapulmonary organ dysfunction, and outcome during the natural course of ARDS and in response to prolonged methylprednisolone treatment. We investigated 29 patients with ARDS. We obtained serial measurements of plasma and BAL procollagen aminoterminal propeptide type I (PINP) and type III (PIIINP) levels and components of the lung injury score (LIS) and MODS score. A reduction in LIS greater than one point from day 1 to day 7 of ARDS divided patients in improvers (group 1, n = 7) and nonimprovers (n = 22). Nonimprovers included those who were recruited (day 9 +/- 3 of ARDS) into a prospective, randomized, double-blind, placebo-controlled trial investigating prolonged methylprednisolone therapy in unresolving ARDS (group 2, n = 17), and those who died (all by day 10 of ARDS) prior to meeting eligibility criteria for the randomized trial (group 3, n = 5). On day 1 of ARDS, plasma PINP or PIIINP levels were elevated in all patients. By day 7 of ARDS, mean plasma PINP or PIIINP levels were unchanged in group 1 but increased significantly in group 2 (p = 0. 0002) and group 3 (p = 0.03). On day 7, patients with plasma PINP levels less than 100 ng/ml were 2.5 times more likely to survive (95% CI: 0.855-7.314), and patients with plasma PIIINP levels greater than 25 ng/ml were nine times more likely to die (95% CI: 1. 418-55.556). In group 2, patients taking placebo (n = 6) had no change in plasma PINP or PIIINP levels over time, while patients treated with methylprednisolone (n = 11) had a rapid and sustained reduction in mean plasma and bronchoalveolar lavage (BAL) PINP and PIIINP levels. By day 3 of treatment, mean plasma PINP and PIIINP levels (ng/ml) decreased from 100 +/- 9 to 45 +/- 8 (p = 0.0001) and 31 +/- 3 to 12 +/- 3 (p = 0.0008), respectively. After 8 to 15 d of methylprednisolone, mean BAL PINP and PIIINP levels (ng/ml) decreased from 63 +/- 25 to 6 +/- 23 (p = 0.002) and 42 +/- 5 to 10 +/- 3 (p = 0.003), respectively. Estimated partial correlation coefficients indicated that as plasma PINP and PIIINP levels decreased over the first 7 d of methylprednisolone treatment, positive end-expiratory pressure, creatinine, bilirubin, and temperature also decreased, while PaO2:FIO2 increased. In early ARDS, plasma PINP and PIIINP levels are elevated and continue to increase over time in those not improving. Among nonimprovers, those randomized to prolonged methylprednisolone treatment had a rapid and significant reduction in plasma and BAL aminoterminal propeptide levels and similar changes in lung injury and MODS scores. These findings provide additional evidence of an association between biological efficacy and physiologic response during prolonged methylprednisolone treatment of unresolving ARDS.

Ventilation in the trauma and surgical patient

Changes in the understanding of the pathophysiology of ARDS and effects of mechanical ventilation with high pressures have led to treatment strategies that resulted in improved survival rates. The central principle in these strategies is to avoid ventilation induced lung injury by allowing the lungs to rest. A number of promising new treatments emphasizing this principle are under investigation. Physicians caring for patients who develop ARDS should make every effort to avoid alveolar overdistention by ventilating patients in the compliant portion of pressure-flow loop and avoid peak inspiratory pressures in excess of 40 cm H2O.

Neutrophil accumulation is reduced during partial liquid ventilation

OBJECTIVE

This study evaluates the ability of perflubron to inhibit pulmonary neutrophil accumulation during partial liquid ventilation (PLV) in the setting of acute lung injury.

DESIGN

Randomized, controlled, nonblinded study.

SETTING

Research laboratory at a university.

SUBJECTS

Male, Sprague-Dawley rats (n = 120, 506 +/- 42 g).

INTERVENTIONS

Animals were divided into eight groups (n = 15 in each group, of which n = 12 for myeloperoxidase content and n = 3 for histologic neutrophil counting): a) GV-CVF group, animals received gas ventilation (GV) with the induction of lung injury using cobra venom factor (CVF); b) PLV-CVF group, animals received partial liquid ventilation before the induction of lung injury; c) PEEP-CVF group, animals received positive end-expiratory pressure (PEEP) before the administration of cobra venom factor; d) CVF-PLV group, animals received partial liquid ventilation after cobra venom factor; e) CVF-PEEP group, animals received PEEP after cobra venom factor; f) PLV only group, animals received partial liquid ventilation only; g) GV only group, animals received gas ventilation only; and h) NVSBA group, nonventilated spontaneous breathing animals.

MEASUREMENTS AND MAIN RESULTS

After the experimental period, total lung myeloperoxidase content was significantly decreased in the PLV-CVF (0.29 +/- 0.08, p = .02) and PEEP-CVF (0.34 +/- 0.04, p = .01) groups when compared with the GV-CVF group (0.62 +/- 0.07). When compared with the GV-CVF group, a trend toward a reduction in myeloperoxidase was observed in the CVF-PLV (0.42 +/- 0.05, p = .07) and the CVF-PEEP (0.39 +/- 0.06, p = .07) groups. When compared with the cobra venom factor only group (GV-CVF 47 +/- 2 neutrophils/high-power field), reductions in neutrophil count were observed in all groups (neutrophils/high-power field): PLV-CVF (20 +/- 2, p = .009); PEEP-CVF (24 +/- 1, p = .01); CVF-PLV (30 +/- 2, p = .03); and CVF-PEEP (37 +/- 1, p = .04).

CONCLUSION

These data suggest that both partial liquid ventilation and PEEP result in a reduction in neutrophil accumulation in the setting of acute lung injury.

Pharmacologic adjuncts to mechanical ventilation in acute respiratory distress syndrome

This article reviews pharmacologic approaches to treating acute respiratory distress syndrome (ARDS). The authors discuss the therapeutic effects of ketoconazole, antioxidants, corticosteroids, surfactant, ketanserin, pentoxifylline, bronchodilators, and almitrine in ARDS. Current animal data and proposed mechanics which may foster future pharmacologic therapies are also examined.

Pneumonia in acute respiratory distress syndrome. A prospective evaluation of bilateral bronchoscopic sampling

We evaluated the diagnostic yield of bilateral bronchoalveolar lavage (BAL) in patients with acute respiratory distress syndrome (ARDS) with suspected ventilator-associated pneumonia (VAP) and compared BAL results from contralateral sites. Ninety-four ARDS patients with suspected VAP underwent 172 bronchoscopies (344 BALs). BAL was processed for quantitative cultures, total cell count and subjected to microscopic analysis for cell differential, presence of intracellular organisms (ICO), and Gram stain. The diagnostic threshold for VAP was a growth of >= 10(4) cfu/ml in BAL culture. Most episodes (68%) had bilateral insignificant bacterial growth. Forty (43%) patients had one or more episodes of VAP. Thirty-three of the 55 (60%) positive bronchoscopies had significant growth in only one side, 18 were right BAL, and 15 were left BAL. Episodes with bilateral significant growth were more likely to be polymicrobial, to have a bacterial growth >= 10(5) cfu/ml in the BAL, and to possess a higher percentage of neutrophils and ICO. Among 65 microorganisms recovered in significant concentration, Pseudomonas aeruginosa occurred in 43% and S. aureus in 15%. Overall, Gram stain had a sensitivity of 54% and a specificity of 87%; and Giemsa stain (> 2% ICO) had a sensitivity of 46% and a specificity of 93%. Antibiotic treatment was modified by the results of BAL cultures in 50 (91%) episodes of pneumonia. In patients with ARDS and suspected VAP, bilateral BAL quantitative bacterial cultures had significant growth on one side only in 19% and in both sides in 13%.

Incidence of acute respiratory distress syndrome: a comparison of two definitions

OBJECTIVES

To determine the incidence and outcome of acute respiratory distress syndrome (ARDS) in children by comparing two commonly used definitions: the lung injury score and the American-European Consensus Conference definition. The causes and risk for developing ARDS were also studied.

METHODS

Part prospective and retrospective analysis of 8100 consecutive hospital admissions from 1 June 1995 to 1 April 1997.

RESULTS

Twenty one patients fulfilled the criteria for ARDS. Both definitions identified the same group of patients. The incidence was 2.8/1000 hospital admissions or 4.2% of paediatric intensive care unit admissions. The main causes were sepsis and pneumonia. Mortality was 13 of 21. Factors predicting death were a high admission paediatric risk of mortality (PRISM) score (30.38 v 18.75) and the presence of multiple organ dysfunction syndrome (92% v 25%).

CONCLUSION

Both definitions identified similar groups of patients. The incidence in this population was higher than that reported elsewhere, but mortality and cause were similar to those in developed countries. Poor outcome was associated with sepsis, a high admission PRISM score, and simultaneous occurrence of other organ dysfunction.

Partial liquid ventilation decreases albumin leak in the setting of acute lung injury

PURPOSE

This study evaluated the ability of partial liquid ventilation (PLV, gas ventilation of the perfluorocarbon-filled lungs) to reduce the amount of lung albumin leak present in the setting of acute lung injury.

MATERIALS AND METHODS

An experimental controlled, randomized design was used. All studies were performed in the liquid ventilation laboratories at the University of Michigan Medical Center. Twenty-five Sprague-Dawley male rats 500+/-50 g were divided into five experimental groups: (1) CVF only (n=5), animals were cobra venom factor (CVF) lung injured; (2) PLV-CVF (n=5) animals received perflubron and PLV before CVF lung injury; (3) CVF-PLV (n=5) animals received PLV after CVF lung injury; (4) PLV only (n=5) animals underwent partial liquid ventilation without lung injury; and (5) Gas only (n=5) animals underwent gas ventilation without lung injury. In all groups iodinated bovine serum albumin (125I-BSA) was delivered by intravenous injection along with CVF or a saline placebo.

RESULTS

When the CVF animals were compared with all other groups, a decrease in albumin leak was observed for all groups when compared with the CVF only controls (P < .001 by ANOVA; CVF only=1.22+/-0.12 versus PLV-CVF=0.46+/-0.08, P < .001; CVF-PLV=0.70+/-0.25, P < .001; PLV only=0.22+/-0.01, P < .001; Gas only=0.17+/-0.02, P < .001).

CONCLUSIONS

These data suggest that intratracheal instillation of perfluorocarbon before or after induction of lung injury results in a reduction in pulmonary albumin leak.

Corticosteroids in life-threatening varicella pneumonia

BACKGROUND

Varicella pneumonia that results in respiratory failure or progresses to the institution of mechanical ventilation carries a significant morbidity and mortality despite intensive respiratory support and antiviral therapy. There has been no reported study of the role of corticosteroids in life-threatening varicella pneumonia.

DESIGN AND METHODS

This was an uncontrolled retrospective and prospective study of all adult patients with a diagnosis of varicella pneumonia who were admitted to the ICUs of the Johannesburg group of academic hospitals in South Africa between 1980 and 1996. Patient demographics, clinical and laboratory features, necessity for mechanical ventilation, and complications were reviewed. The outcome and therapy of varicella pneumonia was evaluated with particular reference to the use of corticosteroids. Patients with comorbid disease and those already taking immunosuppressive agents were excluded. Key endpoints included length of ICU and hospital stay and mortality.

MEASUREMENTS AND RESULTS

Fifteen adult patients were evaluated, six of whom received corticosteroids in addition to antiviral and supportive therapy. These six patients demonstrated a clinically significant therapeutic response. They had significantly shorter hospital (median difference, 10 days; p<0.006) and ICU (median difference, 8 days; p=0.008) stays and there was no mortality, despite the fact that they were admitted to the ICU with significantly lower median ratios between PaO2 and fraction of inspired oxygen than those patients (n=9) who did not receive corticosteroid therapy (86.5 vs 129.5; p=0.045).

CONCLUSION

When used in addition to appropriate supportive care and early institution of antiviral therapy, corticosteroids appear to be of value in the treatment of previously well patients with life-threatening varicella pneumonia. The observations presented in this study are important and should form the basis for a randomized controlled trial, as no other relevant studies or guidelines are available.

The American-European Consensus Conference on ARDS, part 2: Ventilatory, pharmacologic, supportive therapy, study design strategies, and issues related to recovery and remodeling. Acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last 10 years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathologic features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.

The American-European Consensus Conference on ARDS, part 2. Ventilatory, pharmacologic, supportive therapy, study design strategies and issues related to recovery and remodeling

The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last ten years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathological features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.

Acute respiratory distress syndrome

Acute Respiratory Distress Syndrome (ARDS) occurs in a wide range of adult and pediatric critical care settings. This article provides an overview of ARDS including the controversies in definition, a summary of pathophysiology, diagnosis, clinical presentation, and management options. The article also attempts to emphasize new management options in the management of ARDS, and highlights differences between adults and children.

Acute respiratory distress syndrome: an overview

Acute Respiratory Distress Syndrome (ARDS) is a fulminant form of respiratory failure which has diverse aetiology. Although the pathophysiology of the disease is understood in some depth today, much is still elusive and, despite technological advances in intensive care medicine, mortality rates remain high. This article focuses on the key areas of: the inflammatory processes in ARDS, the altered pulmonary physiology, and finally the outcomes, treatments and the need for future research. A knowledge of these aspects is useful to intensive care nurses.

Experimental therapies to support the failing lung

Many conventional therapies are designed to treat acute lung injury. Although evidence exists that improved outcomes are a result of these therapies, mortality remains high in this population. Perhaps one of the key reasons why mortality remains high in the failing lung population is that current therapies do not "cure" the problem; current therapies are designed to support the lung, rather than fix the pulmonary problem. In this paper, a review of new and experimental therapies to support the failing lung are presented. Therapies such as prone positioning, nitric oxide, and mediator therapies are addressed. It is likely that newer therapies offer the most hope for improving the high mortality associated with acute lung injury.

Evolving concepts in the ventilatory management of acute respiratory distress syndrome

With few modifications, a high tidal volume, normoxic, normocapnic ventilation paradigm developed as the standard approach to supporting most critically ill patients. Large tidal volumes, high end-tidal (plateau) alveolar pressures, and low levels of positive end-expiratory pressure are still common in many ICUs during ventilation of acute respiratory distress syndrome (ARDS). A body of scientific literature now suggests that this traditional approach may retard healing of the injured lung. A relatively small but growing number of practitioners are shifting their first priority from optimizing oxygen exchange, oxygen delivery, or respiratory system compliance to ensuring adequate lung protection. This article reviews the basis for concern about traditional ventilatory support in ARDS and develops an approach based on current evidence and newer options for management.

The clinical use of 99m-Tc-labeled WBC scintigraphy in critically ill surgical and trauma patients with occult sepsis

OBJECTIVE

To evaluate the clinical use of radionuclide-labeled white blood cell scintigraphy in the detection of focal sepsis.

DESIGN

Prospective clinical study.

SETTING

A medical/surgical 12-bed intensive care unit (ICU) in a university hospital.

PATIENTS

26 trauma and surgical patients affected by sepsis of unknown origin were studied.

MEASUREMENTS AND RESULTS

After the usual diagnostic approach, patients were submitted to a total body scan by using the patient's leukocytes labeled with technetium-99m (99m-Tc) HMPAO; three scintigraphy were performed within 20 h of tracer injection; the result of scan was completed with all clinical and instrumental data, including ultrasound (US) arnd computed tomography (CT), and the diagnostic efficacy was demonstrated for each patient on discharge from the ICU. The scan was able to detect 20 sites of infection; it was possible to rule out 11 suspected sites; only in two cases was the result considered to be false positive or false negative; in two cases the result was considered to be uncertain. These results show the high sensitivity (95%), specificity (91%) and accuracy (94%) of the method.

CONCLUSIONS

In ICU patients with sepsis, nuclear medicine can provide additional data, as the injection of radionuclide-labeled white blood cells (WBCs) allows the imaging of sites of infection. Analysis of our results suggests that scintigraphy with 99m-Tc-labeled WBCs can be considered a useful tool in the detection of the source of infection.

The role of gallium-67 scintigraphy in diagnosing sources of fever in ventilated patients

OBJECTIVE

To evaluate the diagnostic value of gallium-67 scintigraphy in febrile ventilated patients by correlating the findings of 67Ga scintigraphy to sources of fever and pulmonary density, as determined by a comprehensive protocolized diagnostic evaluation.

DESIGN

Prospective observational study.

PATIENTS

Thirty-two intubated patients on mechanical ventilation for > or = 3 days with fever (> or = 38.3 degrees C) and a new or progressive density on chest radiograph. Twenty patients (21 tests) had adult respiratory distress syndrome (ARDS).

INTERVENTION

Diagnostic evaluation for fever included bronchoscopy with protected specimen brushing and (protected) bronchoalveolar lavage (BAL); computed tomography (CT) of sinuses; cultures of blood, urine, and central lines; and CT of the abdomen in high-risk patients.

MEASUREMENTS AND RESULTS

Uptake of 67Ga was reported as either focal or diffuse pulmonary uptake and extrapulmonary uptake. The combined causes of fever were pneumonia (9), fibroproliferation of late ARDS (7), abdominal process (4), sinusitis (4), urinary tract infection (3), and others (6). Causes of the pulmonary densities were pneumonia (9), ARDS (13), atelectasis (7), congestive heart failure (3), and empyema (1). Marked and diffuse pulmonary uptake was found only in patients with ARDS; however, it was not useful in discriminating those patients with pulmonary fibroproliferation as the sole cause of fever (p = 0.167) from those with infection. 67Ga scintigraphy was inadequate for detecting pneumonia but valuable in identifying extrapulmonary sites of infection in patients with ARDS (p = 0.021).

CONCLUSIONS

67Ga scintigraphy should be considered only as an adjunct diagnostic test in the febrile, ventilated patient who has no obvious source of fever, despite a negative evaluation that includes testing for pneumonia, sinusitis, and urinary tract infection, conditions that are rarely detected by 67Ga scintigraphy.

Diagnostic value of direct examination of protected specimen brush samples in nosocomial pneumonia

The value of direct examination of Giemsa and Gram stains of cytospin preparations of protected specimen brush samples was compared to that of quantitative culture. Sixty-one samples from patients suspected to have nosocomial pneumonia were analysed. Twenty-five samples were positive by quantitative culture, 21 of which contained microorganisms seen by direct examination. The presence of leucocytes was not specific for a positive culture, but in their absence, a positive culture was unlikely. The presence of intracellular organisms always correlated with a positive culture, but was not very sensitive.

Diagnostic imaging of idiopathic adult respiratory distress syndrome (ARDS)/diffuse alveolar damage (DAD) histopathological correlation with radiological imaging

In ten patients with idiopathic adult respiratory distress syndrome (ARDS) who had histopathologically diffuse alveolar damage (DAD), and who did not have specific underlying diseases, we compared the histopathological findings with their radiographic images in order to study the detail analysis of radiographic images and the clinical courses. These patients were roughly classified as having the interstitial pneumonia dominant type (type IP) of idiopathic ARDS, in which alveolar septal thickening, alveolitis, or both were the predominant histological findings and images showed increasing attenuation of lung fields with small honeycomb lung, or the organizing pneumonia dominant type (type OP), in which organizing exudate predominantly filled the alveoli histologically and images showed consolidation shadows with some air. Hyaline membrane was seen very frequently in patients with a short clinical course, and in accordance with a longer clinical course, widespread fibrosis and honeycomb lung covered by organizing hyaline membrane was seen with both types. Patients with type OP in whom collapse of the normal pulmonary structure was less and for whom changes on radiographic images were larger seemed to respond relatively favorably to steroid treatment, as judged from pulmonary function and radiographic images.

Plasma and BAL cytokine response to corticosteroid rescue treatment in late ARDS

BACKGROUND

In late ARDS, a persistent and exaggerated inflammatory response causes recurrent injury to the alveolocapillary barrier and amplification of intra-alveolar fibroproliferation. When ARDS patients fail to improve, corticosteroid (CS) rescue treatment frequently leads to rapid improvements in lung function. We tested the hypothesis that response to CS treatment is related to suppressing the inflammatory response by comparing changes in lung function to inflammatory cytokine (IC) levels in the plasma and BAL.

METHODS

Blood samples were obtained on days 1, 3, 5, and 7 of ARDS, and on days -5, -3, 0 (initiation of treatment), +3, +5, +7, +10, and +14 of CS treatment. Bilateral BAL was obtained on day 1 of ARDS, before administration of CS treatment, and at weekly intervals. We analyzed changes in IC levels during CS treatment in relation to improvements in lung injury score (LIS), indices of endothelial permeability, and final outcome. We also analyzed data to identify timing to a significant reduction in plasma IC levels and predictors of response.

RESULTS

Nine patients entered the study. CS treatment was initiated 15 +/- 9 days into ARDS. Improvement in LIS (> 1-point reduction) was rapid (< 7 days) in five, delayed (< 14 days) in two, and absent in two. Baseline plasma and BAL IC levels in study patients were similar to a previously reported comparison group of 12 ARDS nonsurvivors. No significant changes in plasma and BAL IC levels were observed before CS administration. Following initiation of CS treatment, significant reductions in plasma tumor necrosis factor-alpha and interleukin 6 (IL-6) levels were seen by day 7 in both rapid and delayed responders (p = 0.03). IL-1 beta was significantly reduced by day 5 (p = 0.04) in rapid responders and by day 10 (p = 0.03) in delayed responders. In responders, improvement in LIS and BAL albumin paralleled reduction in plasma and BAL IC levels. At initiation of treatment, rapid responders had significantly lower tumor necrosis factor-alpha and IL-6 levels. Nonresponders had a significantly higher plasma IL-6 level on days 1 to 3 of ARDS (p = 0.004) and lower ratio of arteriolar oxygen tension to inspired oxygen concentration at initiation of treatment (p < 0.01).

CONCLUSIONS

In patients with late ARDS and a low likelihood of survival, prolonged corticosteroid rescue treatment was associated with a reduction in plasma and BAL IC levels and parallel improvements in indices of endothelial permeability and LIS.

Inflammatory cytokines in the BAL of patients with ARDS. Persistent elevation over time predicts poor outcome

BACKGROUND

Inflammatory cytokines (ICs) are important modulators of injury and repair. ICs have been found to be elevated in the BAL of patients with both early and late ARDS. We tested the hypothesis that recurrent injury to the alveolocapillary barrier and amplification of intra-alveolar fibroproliferation observed in nonresolving ARDS is related to a persistent inflammatory response. For this purpose, we obtained serial measurements of BAL IC and correlated these levels with lung injury score (LIS), BAL indexes of endothelial permeability (albumin, total protein [TP]), and outcome.

METHODS

We prospectively studied 27 consecutive patients with severe medical ARDS. Using enzyme-linked immunosorbent assay methods, levels of tumor necrosis factor-alpha (TNF-alpha) and interleukins (IL) 1 beta, 2, 4, 6, and 8 were measured at frequent intervals in both plasma and BAL. In 22 patients, bilateral BAL was obtained on day 1 of ARDS and at weekly intervals when possible. Right and left BALs were analyzed separately for IC levels, total cell count and differential, albumin, TP, and quantitative bacterial cultures.

RESULTS

On day 1 of ARDS, the 10 nonsurvivors had significantly higher (p = 0.0002) BAL TNF-alpha, IL-1 beta, IL-6, and IL-8 levels, which remained persistently elevated over time, indicating a continuous injury process. In contrast, the 12 survivors had a lesser elevation and a rapid reduction over time. Initial BAL IL-2 and IL-4 levels were significantly higher in patients with sepsis (p = 0.006); both increased over time in survivors and nonsurvivors. BAL levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 correlated with BAL albumin and TP concentrations but not with LIS or ratio of arterial oxygen tension to inspired oxygen concentration. BAL: plasma ratios were elevated for all measured cytokines, suggesting a pulmonary origin. On day 1 of ARDS, nonsurvivors had significantly higher (p = 0.04) BAL: plasma ratios for TNF-alpha, IL-1 beta, IL-6, and IL-8. Over time, BAL:plasma ratios for TNF-alpha, IL-1 beta and IL-6 remained elevated in nonsurvivors and decreased in survivors.

CONCLUSIONS

Our findings indicate that an unfavorable outcome in ARDS is associated with an initial, exaggerated, pulmonary inflammatory response that persists unabated over time. Plasma IC levels parallel changes in BAL IC levels. The BAL:plasma ratio results suggest, but do not prove, a pulmonary origin for IC production. BAL TNF-alpha, IL-1 beta, and IL-8 levels correlated with BAL indices of endothelial permeability. In survivors, reduction in BAL IC levels over time was associated with a decline in BAL albumin and TP levels, suggesting effective repair of the endothelial surface. These findings support a causal relationship between degree and duration of lung inflammation and progression of fibroproliferation in ARDS.

Acute respiratory distress syndrome

OBJECTIVE

To review the pathophysiology, epidemiology, and therapy of patients with acute respiratory distress syndrome (ARDS).

DATA SOURCES

Articles pertaining to the pathophysiology, epidemiology, and supportive therapy of ARDS were chosen from a computerized literature search. Recent review articles addressing the specifics of treatment in an intensive care unit are cited rather than restating these specific aspects.

DATA EXTRACTION

Primary literature was chosen in reference to the pathophysiology, epidemiology, and supportive therapy of ARDS. Both human and animal studies were included. Review articles were cited regarding areas of ARDS supportive therapy rather than citing the primary literature.

STUDY SELECTION

Only peer-reviewed primary literature sources were chosen to describe the specifics of pathophysiology and epidemiology. When human data were unavailable, animal studies were cited. Recent review articles were cited for specifics on supportive therapy.

DATA SYNTHESIS

Consensus regarding the definition of ARDS and the difficulties of performing large controlled trials in patients with ARDS has made development of new modalities problematic. Understanding the underlying pathophysiology and risk factors for mortality are key to supportive therapy. Although many pharmacologic agents are being tested in patients with ARDS, attention to the aspects of supportive therapy is the only method to decrease mortality.

CONCLUSION

The mortality of ARDS continues to be 70%. Pharmacists can play an active role in the supportive therapy of patients with ARDS, which is currently the only way to impact mortality.

Establishing the relative accuracy of three new definitions of the adult respiratory distress syndrome

OBJECTIVES

Over the last few years, new definitions of the adult respiratory distress syndrome (ARDS) have been introduced that potentially identify patients earlier in their course of acute lung injury. However, these definitions have never been compared with any of the older and potentially stricter definitions of ARDS to determine if similar patients are eventually identified. We compared new definitions of ARDS--as represented by the Lung Injury Score, a modified Lung Injury Score, and the American-European Consensus Conference definition--against a stricter definition of ARDS to determine their accuracy.

DESIGN

Prospective.

SETTING

Intensive care unit (ICU) patients in a tertiary, university-affiliated city hospital.

PATIENTS

ICU patients with clearly defined at-risk diagnoses for ARDS (group 1, n = 111) and general medical ICU patients without clearly defined at-risk diagnoses for ARDS (group 2, n = 125).

MEASUREMENTS AND MAIN RESULTS

Measurements of hypoxemia, static respiratory system compliance, positive end-expiratory pressure, radiographic changes, and general demographic information were collected. The sensitivity, specificity, positive-predictive value, negative-predictive value, and accuracy of all three new definitions were determined. Accuracy was defined as the true-positive plus the true-negative results divided by the total number of patients. When compared with a stricter definition of ARDS, all three definitions maintained a high degree of accuracy in those patients with a clearly defined at-risk diagnosis (group 1): Lung Injury Score 90.0% (95% confidence interval 84-96); modified Lung Injury Score 97.3% (95% confidence interval 94-100), and the American-European Consensus Conference definition 97.3% (95% confidence interval 94-100). For these at-risk patients, the accuracy of the modified Lung Injury Score and the American-European Consensus Conference definition was significantly better than the Lung Injury Score when compared with the strict definition (p = .027 for both comparisons). Although all three definitions maintained an accuracy of > 90% for general medical ICU patients (group 2), the low frequency of ARDS in these patients (3.4%) produced a low positive-predictive value for all three definitions.

CONCLUSIONS

We conclude that the Lung Injury Score, the modified Lung Injury Score, and the American-European Consensus Conference definition identify similar patients, provided that these methods are applied to patients with clearly defined at-risk diagnoses for ARDS.

The role of bronchoalveolar lavage in the diagnosis of bacterial pneumonia

Bronchoalveolar lavage (BAL) has become an invaluable diagnostic tool with important clinical implications in both opportunistic infections and the pulmonary pathology of immunologic disease. Until recently, the use of BAL was limited primarily to two areas: the study of interstitial lung diseases and the diagnosis of lung infections by opportunistic microorganisms in severely immunocompromised patients with lung infiltrates. Over the past decade, the use of BAL has been expanded to include the conventional diagnosis of bacterial pneumonia in non-immunocompromised patients. In the past, different clinical studies proposed using BAL to quantify cultures in the sample obtained as a means of increasing the tool's effectiveness. Recent developments have led to a number of newer applications of BAL, such as bronchoscopic BAL, non-bronchoscopic BAL and protected BAL. The most important use of BAL in the non-immunocompromised patient is the diagnosis of pneumonia in the mechanically ventilated patient.

Prevention and therapy of the adult respiratory distress syndrome

The complex pathophysiology of adult respiratory distress syndrome (ARDS) makes preventive and therapeutic concepts difficult. Ample experimental evidence indicates that ARDS can be prevented by blocking systemic inflammatory agents. Clinically, only heparin, for inhibition of coagulation phenomena, is presently used among this array of approaches. Corticosteroids have not proven to be beneficial in ARDS. Alternative antiinflammatory agents are being proposed and are under current clinical investigation (e.g. indomethacin, acetylcysteine, alpha 1-proteinase inhibitor, antitumor necrosis factor, interleukin 1 receptor antagonist, platelet-activating factor antagonists). Symptomatic therapeutic strategies in early ARDS include selective pulmonary vasodilation (preferably by inhaled vasorelaxant agents) and optimal fluid balance. Transbronchial surfactant application, presently tested in pilot studies, may be available for ARDS patients in the near future and may have acute beneficial effects on gas exchange, pulmonary mechanics, and lung hemodynamics; its impact on survival cannot be predicted at the present time. Strong efforts should be taken to reduce secondary nosocomial pneumonia in ARDS patients and thus avoid the vicious circle of pneumonia, sepsis from lung infection, and perpetuation of multiple organ dysfunction syndrome. Optimal respirator therapy should be directed to ameliorate gas-exchange conditions acutely but at the same time should aim at minimizing potentially aggravating side effects of artificial ventilation (barotrauma, O2 toxicity). Several new techniques of mechanical ventilation and the concept of permissive hypercapnia address these aspects. Approaches with extracorporeal CO2 removal and oxygenation are being used in specialized centers.

Persistent elevation of inflammatory cytokines predicts a poor outcome in ARDS. Plasma IL-1 beta and IL-6 levels are consistent and efficient predictors of outcome over time

BACKGROUND

Inflammatory cytokines have been related to the development of adult respiratory distress syndrome (ARDS), shock, and multiple organ dysfunction syndrome (MODS). We tested the hypothesis that unfavorable outcome in patients with ARDS is related to the presence of a persistent inflammatory response. For this purpose, we evaluated the behavior of inflammatory cytokines during progression of ARDS and the relationship of plasma inflammatory cytokines with clinical variables and outcome.

METHODS

We prospectively studied 27 consecutive patients with severe medical ARDS. Plasma levels of tumor necrosis factor alpha (TNF-alpha) and interleukins (ILs) 1 beta, 2, 4, 6, and 8 were measured (enzyme-linked immunosorbent assay [ELISA] method) on days 1, 2, 3, 5, 7, 10, and 12 of ARDS and every third day thereafter while patients were receiving mechanical ventilation. Subgroups of patients were identified based on outcome, cause of ARDS, presence or absence of sepsis, shock, and MODS at the time ARDS developed. Subgroups were compared for levels of plasma inflammatory cytokines on day 1 of ARDS and over time.

RESULTS

Of the 27 patients, 13 survived ICU admission and 14 died (a mortality rate of 52%). Overall mortality was higher in patients with sepsis (86 vs 38%, p < 0.02). The mean initial plasma levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 were significantly higher in nonsurvivors (p < 0.0001) and in those patients with sepsis (p < 0.0001). Plasma levels of IL-1 beta (p < 0.01) and IL-6 (p = 0.03) were more strongly associated with patient outcome than cause of ARDS (p = 0.8), lung injury score (LIS), APACHE II score, sepsis (p = 0.16), shock, or MODS score. Plasma levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 remained significantly elevated over time (p < 0.0001) in those who died. Although it was the best early predictor of death (p < 0.001), plasma IL-2 > 200 pg/mL lost its usefulness after the first 48 h. A plasma IL-1 beta or IL-6 level > 400 pg/mL on any day in the first week of ARDS was associated with a low likelihood of survival.

CONCLUSIONS

Our findings indicate that unfavorable outcome in acute lung injury is related to the degree of inflammatory response at the onset and during the course of ARDS. Patients with higher plasma levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 on day 1 of ARDS had persistent elevation of these inflammatory cytokines over time and died. Survivors had lesser elevations of plasma inflammatory cytokines on day 1 of ARDS and a rapid reduction over time. Plasma IL-1 beta and IL-6 levels were consistent and efficient predictors of outcome.

The acute respiratory distress syndrome

ARDS is a complex response of the lung to direct (inhalational) and indirect (hematogenous) insults. It is easy to be pessimistic about the benefit of the approaches we have described, but there is evidence that overall survival has improved in recent years. To maintain this progress, new therapies for ARDS must be rigorously evaluated, and their routine use should be recommended only after careful scrutiny of the evidence. Such a course will eliminate the unnecessary risks and costs often associated with unproved therapies.

Pulmonary fibrosis correlates with outcome in adult respiratory distress syndrome. A study in mechanically ventilated patients

STUDY OBJECTIVE

The present study was carried out to evaluate the prognostic value of pulmonary fibrosis diagnosed on the basis of pulmonary samples obtained by fiberscopic transbronchial lung biopsy (TBLB) in patients treated for severe established adult respiratory distress syndrome (ARDS).

DESIGN

Prospective cohort study.

SETTING

Intensive Care Unit of a University Hospital.

PATIENTS

Consecutive patients with a diagnosis of established ARDS.

INTERVENTIONS

Samples of pulmonary tissue (3 to 6 in each patient) were obtained by fiberoptic TBLB. Severity of pulmonary fibrosis was assessed based on pathologic changes. Hematoxylin and eosin and Masson's trichrome stains were performed on each tissue sample.

MAIN RESULTS

Twenty-two lung specimens were obtained from 25 consecutive patients with ARDS of various origin (postsurgical complications, 7 patients; multiple trauma, 8 patients; medical problems, 7 patients). Transbronchial lung biopsy was complicated by small or moderate hemorrhage in three patients. No case of pneumothorax was identified. Pathologic findings showed that 14 patients (64%) had pulmonary fibrosis, either mild (9 patients) or moderate to severe fibrosis (5 patients). In the patients with pulmonary fibrosis, mortality rate was 57% (8 out of 14 patients), which was significantly different (p < 0.02) from the 0% mortality rate observed in patients without pulmonary fibrosis. Severity of pulmonary fibrosis (mild vs moderate and severe) did not influence outcome. With the exception of pathologic findings, characteristics of patients with and without pulmonary fibrosis (PaO2, PaCO2, the ratio of PaO2 to fraction of inspired oxygen, and positive end-expiratory pressure) were not different.

CONCLUSION

In the study patients, pulmonary fibrosis diagnosed on the basis of TBLB was closely related to fatality in established ARDS.