Interest of a therapeutic optimization strategy in severe ARDS

Extracorporeal carbon dioxide removal in acute hypoxaemic respiratory failure: a systematic review, Bayesian meta-analysis and trial sequential analysis

Purpose:

To assess the safety and efficacy of extracorporeal carbon dioxide removal (ECCO2R)versusstandard care in patients with acute hypoxaemic respiratory failure (AHRF).

Methods:

MEDLINE, Embase and clinical trial registries were searched from 1994 to 31 December 2021. We included randomised controlled trials (RCTs) and observational studies. Pairs of reviewers independently extracted data and assessed the risk of bias. The primary outcome was mortality. Secondary outcomes included ventilator-free days, length of stay, safety and adverse events and physiological changes. As a primary analysis, we performed a meta-analysis of mortality until day 30 using a Bayesian random effects model. We then performed a trial sequential analysis of RCTs.

Results:

21 studies met inclusion criteria: three RCTs, enrolling 531 patients, and 18 observational studies. In a pooled analysis of RCTs, the posterior probability of increased mortality with the use of ECCO2R was 73% (relative risk 1.19, 95% credible interval 0.70–2.29). There was substantial heterogeneity in the reporting of safety and adverse events. However, the incidence of extra and intracranial haemorrhage was higher (relative risk 3.00, 95% credible interval 0.41–20.51) among those randomised to ECCO2R. Current trials have accumulated 80.8% of the diversity-adjusted required information size and the lack of effect reaches futility for a 10% absolute risk reduction in mortality.

Conclusions:

The use of ECCO2R in patients with AHRF is not associated with improvements in clinical outcomes. Furthermore, it is likely that further trials of ECCO2R aiming to achieve an absolute risk reduction in mortality of ≥10% are futile.

Drainage of transudative pleural effusion: how does it affect weaning from mechanical ventilation?

Background

Pleural collections of the transudative type occur frequently in patients who need mechanical ventilation (MV). Treatment of the etiology of the effusion takes a prolonged duration of time. The study intended to assess the effect of transudative effusion drainage through chest tube on the process of weaning from MV.

Results

No statistically significant difference was found between the two studied groups regarding age, sex, and comorbidities. Total duration of MV was significantly shorter in patients of group I compared with patients of group II (P = 0.002). Successful weaning from MV within 2 days after the start of the study was statistically significantly more achieved in patients of group I (56.7%) compared with patients of group II (23.3%) (P = 0.017). One and 3 days after beginning of the study, patients in group I showed a significant improvement in oxygenation as demonstrated by a statistically significantly higher value of PaO2/FiO2 ratio compared with patients of group II (P = 0.003 and 0.008, respectively).

Conclusion

More work is needed to determine the physiological benefits of transudate pleural effusion drainage and the effect of the specific procedure on the clinical parameters. Further studies are needed to study different modalities or tools of drainage of transudate effusion and the effect of each on the different clinical outcomes in comparison with each other to reach the optimum way of drainage of transudate effusion with the best results and least complications.

Utility of pleural effusion drainage in the ICU: An updated systematic review and META-analysis

PURPOSE

The effects on the respiratory or hemodynamic function of drainage of pleural effusion on critically ill patients are not completely understood. First outcome was to evaluate the PiO₂/FiO₂ (P/F) ratio before and after pleural drainage.

SECONDARY OUTCOMES

evaluation of A-a gradient, End-Expiratory lung volume (EELV), heart rate (HR), mean arterial pressure (mAP), left ventricular end-diastolic volume (LVEDV), stroke volume (SV), cardiac output (CO), ejection fraction (EF), and E/A waves ratio (E/A). A tertiary outcome: evaluation of pneumothorax and hemothorax complications.

MATERIALS AND METHODS

Searches were performed on MEDLINE, EMBASE, COCHRANE LIBRARY, SCOPUS and WEB OF SCIENCE databases from inception to June 2018 (PROSPERO CRD42018105794).

RESULTS

We included 31 studies (2265 patients). Pleural drainage improved the P/F ratio (SMD: -0.668; CI: -0.947-0.389; p < .001), EELV (SMD: -0.615; CI: -1.102-0.219; p = .013), but not A-a gradient (SMD: 0.218; CI: -0.273-0.710; p = .384). HR, mAP, LVEDV, SV, CO, E/A and EF were not affected. The risks of pneumothorax (proportion: 0.008; CI: 0.002-0.014; p = .138) and hemothorax (proportion: 0.006; CI: 0.001-0.011; p = .962) were negligible.

CONCLUSIONS

Pleural effusion drainage improves oxygenation of critically ill patients. It is a safe procedure. Further studies are needed to assess the hemodynamic effects of pleural drainage.

Rapid Reduction of Oxygenation Index by Employment of a Recruitment Technique in Patients with Severe ARDS

Mechanical ventilation of patients with acute respiratory distress syndrome (ARDS) may contribute to pulmonary injury and systemic inflammation. The objective of this study was to examine the safety and efficacy of a recruitment maneuver that rapidly improves atelectasis and oxygenation, and in so doing may reduce the potential for ventilator-induced lung injury. Nineteen patients with severe ARDS (defined as PaO2: FiO2 ≤ 150) from diverse etiologies were turned prone and a positive pressure of 40 cmH2O was applied for a period of 90 seconds. This pressure was increased in 5 cmH2O increments in subsequent maneuvers to a maximum of 50 cmH2O if there was an inadequate initial response. Subsequently pressure-limited mechanical ventilation with a PEEP of 15 cmH2O was instituted to prevent derecruitment. Peak pressures were maintained at ≤35 cmH2O. Outcome measures were oxygenation index, PaO2: FiO2 ratio, and alveolar-arterial oxygen difference. The oxygenation index decreased from a median of 31 cmH2O/mmHg to 14 cmH2O/mmHg immediately after recruitment and to 11 cmH2O/mmHg (p < 0.0001) 24 hours later. The A-aDO2 improved from 454 mmHg to 128 mmHg (p < 0.0001) and the PaO2:FiO2 ratio from 75 to 218 (p < 0.0001) 24 hours later. Twenty-five percent of patients had PaO2:FiO2 ratios of more than 300 mmHg at 24 hours. Mean airway pressure increased by 3 cmH2O initially, from 23 cmH2O to 26 cmH2O as a consequence of the increase in PEEP, but this had decreased to 25 cmH2O after 24 hours. There were no significant complications. Rapid reductions in FiO2 can be achieved safely by the implementation of a relatively simple recruitment technique.

Effects of pleural effusion drainage on oxygenation, respiratory mechanics, and hemodynamics in mechanically ventilated patients

OBJECTIVES

In mechanically ventilated patients, the effect of draining pleural effusion on oxygenation is controversial. We investigated the effect of large pleural effusion drainage on oxygenation, respiratory function (including lung volumes), and hemodynamics in mechanically ventilated patients after ultrasound-guided drainage. Arterial blood gases, respiratory mechanics (airway, pleural and transpulmonary pressures, end-expiratory lung volume, respiratory system compliance and resistance), and hemodynamics (blood pressure, heart rate, and cardiac output) were recorded before and at 3 and 24 hours (H24) after pleural drainage. The respiratory settings were kept identical during the study period.

MEASUREMENTS AND MAIN RESULTS

The mean volume of effusion drained was 1,579 ± 684 ml at H24. Uncomplicated pneumothorax occurred in two patients. Respiratory mechanics significantly improved after drainage, with a decrease in plateau pressure and a large increase in end-expiratory transpulmonary pressure. Respiratory system compliance, end-expiratory lung volume, and PaO2/FiO2 ratio all improved. Hemodynamics were not influenced by drainage. Improvement in the PaO2/FiO2 ratio from baseline to H24 was positively correlated with the increase in end-expiratory lung volume during the same time frame (r = 0.52, P = 0.033), but not with drained volume. A high value of pleural pressure or a highly negative transpulmonary pressure at baseline predicted limited lung expansion following effusion drainage. A lesser improvement in oxygenation occurred in patients with ARDS.

CONCLUSIONS

Drainage of large (≥500 ml) pleural effusion in mechanically ventilated patients improves oxygenation and end-expiratory lung volume. Oxygenation improvement correlated with an increase in lung volume and a decrease in transpulmonary pressure, but was less so in patients with ARDS.

Extracorporeal carbon dioxide removal for patients with acute respiratory failure secondary to the acute respiratory distress syndrome: a systematic review

Acute respiratory distress syndrome (ARDS) continues to have significant mortality and morbidity. The only intervention proven to reduce mortality is the use of lung-protective mechanical ventilation strategies, although such a strategy may lead to problematic hypercapnia. Extracorporeal carbon dioxide removal (ECCO₂R) devices allow uncoupling of ventilation from oxygenation, thereby removing carbon dioxide and facilitating lower tidal volume ventilation. We performed a systematic review to assess efficacy, complication rates, and utility of ECCO₂R devices. We included randomised controlled trials (RCTs), case-control studies and case series with 10 or more patients. We searched MEDLINE, Embase, LILACS (Literatura Latino Americana em Ciências da Saúde), and ISI Web of Science, in addition to grey literature and clinical trials registries. Data were independently extracted by two reviewers against predefined criteria and agreement was reached by consensus. Outcomes of interest included mortality, intensive care and hospital lengths of stay, respiratory parameters and complications. The review included 14 studies with 495 patients (two RCTs and 12 observational studies). Arteriovenous ECCO₂R was used in seven studies, and venovenous ECCO₂R in seven studies. Available evidence suggests no mortality benefit to ECCO₂R, although post hoc analysis of data from the most recent RCT showed an improvement in ventilator-free days in more severe ARDS. Organ failure-free days or ICU stay have not been shown to decrease with ECCOvR. Carbon dioxide removal was widely demonstrated as feasible, facilitating the use of lower tidal volume ventilation. Complication rates varied greatly across the included studies, representing technological advances. There was a general paucity of high-quality data and significant variation in both practice and technology used among studies, which confounded analysis. ECCO₂R is a rapidly evolving technology and is an efficacious treatment to enable protective lung ventilation. Evidence for a positive effect on mortality and other important clinical outcomes is lacking. Rapid technological advances have led to major changes in these devices and together with variation in study design have limited applicability of analysis. Further well-designed adequately powered RCTs are needed.

Pleural effusions on the intensive care unit; hidden morbidity with therapeutic potential

Despite 50-60% of intensive care patients demonstrating evidence of pleural effusions, there has been little emphasis placed on the role of effusions in the aetiology of weaning failure. Critical illness and mechanical ventilation lead to multiple perturbations of the normal physiological processes regulating pleural fluid homeostasis, and consequently, failure of normal pleural function occurs. Effusions can lead to deleterious effects on respiratory mechanics and gas exchange, and when extensive, may lead to haemodynamic compromise. The widespread availability of bedside ultrasound has not only facilitated earlier detection of pleural effusions but also safer fluid sampling and drainage. In the majority of patients, pleural drainage leads to improvements in lung function, with data from spontaneously breathing individuals demonstrating a consistent symptomatic improvement, while a meta-analysis in critically ill patients shows an improvement in oxygenation. The effects on respiratory mechanics are less clear, possibly reflecting heterogeneity of underlying pathology. Limited data on clinical outcome from pleural fluid drainage exist; however, it appears to be a safe procedure with a low risk of major complications. The current level of evidence would support a clinical trial to determine whether the systematic detection and drainage of pleural effusions improve clinical outcomes.

Utility of draining pleural effusions in mechanically ventilated patients

PURPOSE OF REVIEW

Pleural effusions are prevalent in mechanically ventilated patients, and clinicians frequently consider draining the effusions. It is controversial whether patients benefit from pleural drainage in terms of either physiological or clinical outcomes.

RECENT FINDINGS

Pleural drainage may be undertaken for a variety of reasons. Effusions are an important potential source of infection in patients with undifferentiated sepsis. Pleural drainage may improve hypoxemia or lung mechanics, but the physiological response depends on a complex interplay between lung and chest wall compliance, applied positive end-expiratory pressure and drainage volume. Pleural effusions may be associated with significant cyclic lung recruitment and collapse during tidal ventilation. Because effusions are primarily accommodated by descent of the diaphragm, they can also impair diaphragm mechanics significantly. There is very limited data in the literature to support the use of pleural drainage to accelerate liberation from mechanical ventilation, and there are no randomized controlled trials published to date.

SUMMARY

Pleural drainage may benefit certain patient populations based on individual physiological considerations, but randomized controlled trials evaluating the impact on weaning outcomes are lacking. Future research efforts should focus on identifying patient populations most likely to benefit and clarify the mechanisms by which weaning may be accelerated after pleural drainage.

Utility and safety of draining pleural effusions in mechanically ventilated patients: a systematic review and meta-analysis

INTRODUCTION

Pleural effusions are frequently drained in mechanically ventilated patients but the benefits and risks of this procedure are not well established.

METHODS

We performed a literature search of multiple databases (MEDLINE, EMBASE, HEALTHSTAR, CINAHL) up to April 2010 to identify studies reporting clinical or physiological outcomes of mechanically ventilated critically ill patients who underwent drainage of pleural effusions. Studies were adjudicated for inclusion independently and in duplicate. Data on duration of ventilation and other clinical outcomes, oxygenation and lung mechanics, and adverse events were abstracted in duplicate independently.

RESULTS

Nineteen observational studies (N = 1,124) met selection criteria. The mean PaO2:FiO2 ratio improved by 18% (95% confidence interval (CI) 5% to 33%, I2 = 53.7%, five studies including 118 patients) after effusion drainage. Reported complication rates were low for pneumothorax (20 events in 14 studies including 965 patients; pooled mean 3.4%, 95% CI 1.7 to 6.5%, I2 = 52.5%) and hemothorax (4 events in 10 studies including 721 patients; pooled mean 1.6%, 95% CI 0.8 to 3.3%, I2 = 0%). The use of ultrasound guidance (either real-time or for site marking) was not associated with a statistically significant reduction in the risk of pneumothorax (OR = 0.32; 95% CI 0.08 to 1.19). Studies did not report duration of ventilation, length of stay in the intensive care unit or hospital, or mortality.

CONCLUSIONS

Drainage of pleural effusions in mechanically ventilated patients appears to improve oxygenation and is safe. We found no data to either support or refute claims of beneficial effects on clinically important outcomes such as duration of ventilation or length of stay.

[Diagnosis and management of pleural effusions in critically iII patients]

INTRODUCTION

Pleural effusions are common in ICU patients. Causes include massive fluid resuscitation in shock, pneumonia--either community acquired or nosocomial, cardiac insufficiency, hypoalbuminemia and hepatic impairment. Pleural effusions frequently complicate cardiac and abdominal surgery and haemothorax may complicate trauma.

STATE OF THE ART

The incidence of pleural effusions in the intensive care unit (ICU) varies depending on the screening method used, from about 8% for physical examination to more than 60% for routine ultrasonography. In the absence of clinical parameters to exclude infection pleurocentesis remains an essential aspect of management and is not contraindicated mechanical ventilation. This review of the diagnosis and management of pleural effusions in ICU patients reports the most recent data from the literature. Pleurocentesis can be performed safely in the ICU, even in mechanically ventilated patients. The absence of reliable clinical or laboratory test criteria for determining the cause of pleural effusions and the potentially devastating consequences of failing to diagnose and treat pleural infection are strong reasons to perform pleurocentesis in patients with clinically detectable pleural effusions and no contraindication to the procedure.

PERSPECTIVES

Although the data reviewed indicate that the diagnosis and treatment of pleural effusions should follow the same rules in the ICU as they do elsewhere, several incompletely resolved issues deserve further investigation. These are summarised in an agenda for future research.

Pleural effusions in the intensive care unit

The incidence of pleural effusions in the intensive care unit varies depending on the screening methods, from approximately 8% for physical examination to more than 60% for routine ultrasonography. Several factors contribute to the occurrence of pleural effusions in intensive care unit patients: large amounts of intravenous fluid are often administered, pneumonia is common, and heart failure, atelectasis, extravascular catheter migration, hypoalbuminemia, or liver disease are present in many intensive care unit patients. In surgical intensive care units, cardiac or abdominal surgery is often followed by pleural effusions, and in trauma patients, hemothorax is a dreaded event. Because no clinical parameter excludes pleural infection, and because of the impact of thoracentesis on diagnosis and treatment, this procedure should be performed unless contraindicated. Thoracentesis is safe in mechanically ventilated patients. The author discusses the following points regarding pleural effusions in the intensive care unit: screening intensive care unit patients for pleural effusion, safety of thoracentesis in patients receiving invasive mechanical ventilation, distinguishing exudates from transudates, and diagnosing and managing infected pleural effusions in critically ill patients. Lastly, the author suggests a research agenda for pleural effusions in intensive care unit patients.

Survival of severe ARDS with five-organ system failure following burns and inhalation injury in a 15-year-old patient

OBJECTIVE

To show the effectiveness of an integrated therapeutical approach in a severe case of acute respiratory distress syndrome (ARDS) following burns, inhalation injury with therapy-refractory oxygenation under maximized ventilatory settings, and an overall complicated clinical course.

PATIENT AND METHODS

Case report of a patient with severe inhalation injury and burns in an intensive care unit setting, undergoing cardiopulmonary resuscitation (CPR), nitric oxide (NO)-inhalation, surfactant-, kinetic-, and urodilatin-therapy.

CASE REPORT

A 15-year-old male presented with deep dermal and full thickness thermal injuries involving 25% of his total body surface area. Shortly after presentation, the patient developed therapy-refractory respiratory failure, cardiac arrest, and subsequently suffered five-organ system failure (lung, heart, gastrointestinal, liver, kidney), in addition to burn injury, and ischemia related cerebral lesions. The patient was successfully treated with cardiac resuscitation, extra corporeal membrane oxygenation (ECMO), NO, kinetic therapy, surfactant, urodilatin, and other standard intensive care regimens. Three months post-trauma the patient was discharged home, nearly fully recovered.

CONCLUSIONS

In a patient with severe ARDS, oxygenation failure under maximized ventilatory settings, and subsequent five-organ system failure, an integrated therapeutical approach comprising ECMO, NO, kinetic therapy, surfactant, and urodilatin did cross-bridge respiratory and vital functions, enabling overall survival.

Comparison of prone positioning and continuous rotation of patients with adult respiratory distress syndrome: results of a pilot study

OBJECTIVE

To compare prone positioning and continuous rotational therapy with respect to oxygenation and hemodynamics in patients suffering from adult respiratory distress syndrome (ARDS).

DESIGN

Randomized, prospective pilot study.

SETTING

Intensive care unit at a university hospital.

PATIENTS

Twenty-six mechanically ventilated patients with ARDS from nontraumatic causes.

INTERVENTIONS

Twelve patients were turned prone (group 1), 14 patients underwent continuous axial rotation from one lateral position to the other with a maximum angle of 124 degrees in specially designed beds (group 2). All patients had received inhaled nitric oxide (NO) therapy before positioning.

MEASUREMENTS AND MAIN RESULTS

Gas exchange and hemodynamics were assessed using a pulmonary artery catheter. In both groups, an improvement in PaO2/RFIO2-ratio and intrapulmonary shunt fraction occurred after initiation of NO as well as during the first 72 hrs of positioning therapy. During the study period, seven patients died in group 1 and nine patients in group 2 (p = NS). Comparing the areas under the curve during the first 72 hrs, no significant differences with respect to PaO2/FIO2-ratio, PaCO2, positive end-expiratory and peak inspiratory pressure levels, intrapulmonary shunt fraction, the alveolar-arterial oxygen difference, and oxygen delivery and consumption, as well as cardiac index, pulmonary and arterial blood pressures, and pulmonary arterial occlusion pressure could be detected between the groups. Prone positioning was tolerated well, continuous rotational therapy had to be modified according to hemodynamic instability in three patients.

CONCLUSIONS

In severe lung injury, continuous rotational therapy seems to exert effects comparable to prone positioning and could serve as alternative when prone positioning seems inadvisable.

Inhaled nitric oxide and acute lung injury

The nitric oxide (NO) field has been one of the most exciting scientific ventures over the past 10 years. Among the researches developed, the use of inhalation of NO gas allowed us to propose this therapy in lung diseases with promising results. Because of its property as a "selective" pulmonary vasodilator and because of its apparent clinical safety, inhaled NO has been proposed in acute lung injury (ALI) to improve severe hypoxemia. In this situation, the abnormal ventilation-perfusion ratio is improved by inhaled NO, limiting arterial hypoxia. The major clinical trials performed in adults, however, have failed to show any benefit on mortality and on mechanical ventilation requirements. Inhaled NO has been shown as an efficient therapy in pediatric ALI, probably because of a lower comorbidity. Because of the inhaled NO uptake by the lung, the extra vascular lung effects might be in the future the most important development in relation with platelet anti-agregant and anti-inflammatory properties.

Acute respiratory distress syndrome: resource use and outcomes in 1985 and 1995, trends in mortality and comorbidities

PURPOSE

The purpose of this study was to compare resource consumption and mortality between (ARDS) patients with adult respiratory distress syndrome treated at our center in 1985 (45 patients) and those treated in 1995.

MATERIALS AND METHODS

This was a retrospective observational study, considering trauma and nontrauma ARDS separately. We recorded severity index scores (APACHE III), infectious complications and multiorgan failure, intensive care unit (ICU) resource consumption (TISS 28), length of stay, time on mechanical ventilation, and ICU mortality.

RESULTS

We found no variation in overall ARDS mortality and no reduction in mortality in the ARDS trauma group (43.5% in 1985 vs. 38.5% in 1995, not significant) but a significant increase in mortality among nontrauma septic ARDS patients (68.2% vs. 82.9%, P < .001), largely attributable to the new comorbidities of human immunodeficiency virus (HIV) infection and hematologic malignancy. TISS-28 showed an overall reduction over this time period (49.7 +/- 6.6 vs. 38.3 +/- 9.7, P < .001), due to fewer monitoring measures, particularly a lower use of pulmonary artery catheter. There were no overall changes in length of stay or days on mechanical ventilation between 1985 and 1995, but these variables did increase among the trauma subgroup.

CONCLUSION

In our setting, mortality remained constant from 1985 to 1995 among ARDS trauma patients but not among nontrauma ARDS patients because of the new case-mix of the latter population, which now includes HIV and other immunodepressed patients.

Transtracheal oxygen delivery

Tracheal insufflation of oxygen has at least three major uses for chronic oxygen supplementation through a percutaneous catheter, it is an adjunctive measure to enhance gas exchange during mechanical ventilation, and it provides an emergency therapy for oxygen delivery with upper airway obstruction. In this article the mechanisms of gas exchange and techniques of oxygen delivery are described for each of these major uses.

Nitric oxide and almitrine: the definitive answer for hypoxemia

Hypoxia-induced by acute lung injury results from abnormal ventilation/perfusion ratio distribution towards shunt or low ventilation/perfusion zones. Pharmacological modification of pulmonary blood flow distribution improving ventilation/perfusion ratio should correct hypoxia. The development of inhaled nitric oxide therapy had confirmed this concept, but with a relatively high proportion of 'non responders'. Then development of other drugs used alone or in association with nitric oxide may reinforce the benefit of nitric oxide. This has been tested with almitrine bismesylate, a lipophilic drug that reinforce hypoxic pulmonary vasoconstriction. Using inhaled nitric oxide in combination with almitrine, several studies in adult respiratory distress syndrome or acute lung injury patients have shown spectacular results in term of PaO2 and pulmonary shunt reduction. Moreover, the proportion of responders to this combination seems largely great than those observed for each drug alone. In conclusion, pulmonary blood flow manipulation improving ventilation/perfusion mismatching is one of the major strategies to correct severe hypoxia.

Mechanical ventilation of patients with acute lung injury

Ventilatory management of patients with acute lung injury (ALI), particularly its most severe subset, acute respiratory distress syndrome (ARDS), is complex. Newer lung protective strategies emphasize measures to enhance alveolar recruitment and avoid alveolar overdistention, thus minimizing the risk of ventilator-induced lung injury (VILI). Key components of such strategies include the use of smaller-than-conventional tidal volumes which maintain peak transpulmonary pressure below the pressure associated with overdistention, and titration of positive end-expiratory pressure to promote maximal alveolar recruitment. Novel techniques, including prone positioning, inverse ratio ventilation, tracheal gas insufflation, and high frequency ventilation, are considerations in severe ARDS. No single approach is best for all patients; adjustment of ventilatory parameters to individual characteristics, such as lung mechanics and gas exchange, is required.

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.

An approach to the treatment of severe adult respiratory failure

OBJECTIVES

The purpose of this article is to evaluate outcome in adult patients with severe respiratory failure managed with an approach using (1) limitation of end inspiratory pressure, (2) inverse ratio ventilation, (3) titration of PEEP by SvO2, (4) intermittent prone positioning, (5) limitation of FiO2, (6) diuresis, (7) transfusion, and (8) extracorporeal life support (ECLS) if patients failed to respond.

PATIENTS AND METHODS

This study was designed as a retrospective review in the intensive care unit of a tertiary referral hospital. One-hundred forty-one consecutive patients with hypoxic (n = 135) or hypercarbic (n = 6) respiratory failure referred for consideration of ECLS between 1990 and 1996. Overall, initial PaO2/FiO2 (P/F) ratio was 75+/-5 (median = 66).

RESULTS

Lung recovery occurred in 67% of patients and 62% survived. Forty-one patients improved without ECLS (83% survived); 100 did not and were supported with ECLS (54% survived). Survival was greater in patients cannulated within 12 hours of arrival (59%) compared with those cannulated after 12 hours (40%, P < .05). Multiple logistic regression identified age, duration of mechanical ventilation before transfer, four or more dysfunctional organs, and the requirement for ECLS as independent predictors of mortality.

CONCLUSIONS

An approach that emphasizes lung protection and early implementation of extracorporeal life support is associated with high rates of survival in patients with severe respiratory failure.

Cytokines and soluble cytokine receptors in pleural effusions from septic and nonseptic patients

The balance between proinflammatory cytokines and their inhibitors has rarely been investigated in pleural effusions of nonmalignant or noninfectious origin. To evaluate the impact of a lung and/or intrathoracic infection in such a circumstance, we compared the levels of proinflammatory cytokines (interleukin-8 [IL-8]); tumor necrosis factor-alpha (TNF-alpha); the cytokine antagonists and inhibitors (IL-1 receptor antagonist [IL-1ra]) and soluble TNF receptors Types I and II (sTNFRI, sTNFRII); and antiinflammatory cytokines (transforming growth factor-beta [TGF-beta]) in pleural effusion and plasma from septic (n = 15) and nonseptic (n = 9) patients. In addition, we analyzed the levels of IL-6 and its soluble receptor (sIL-6R). Bronchoalveolar lavage fluids (BALFs) were also studied in a few septic patients. High and nonsignificantly different levels of cytokines and inhibitors were detected in both groups of patients. The levels of IL-6 and sTNFRI and sTNFRII in pleural effusion were higher than in plasma, whereas the levels of IL-1ra and sIL-6R were higher in plasma. The levels of sIL-6R influenced the bioactivity of IL-6. There was no correlation between the levels of cytokines in plasma and in pleural effusion. In contrast, a significant correlation was observed for the soluble receptors sIL-6R (r = 0.67, p < 0.001), sTNFRI (r = 0.76, p < 0.001) and sTNFRII (r = 0.66, p = 0.001). Furthermore, a high correlation was found between the levels of both forms of sTNFRs in plasma (r = 0.95, p < 0.001) and in pleural effusion (r = 0.79, p < 0.001). In addition, a correlation was observed between the levels of TGF-beta in pleural effusion and in BALF. The highest levels of some markers in plasma and of others in pleura argue in favor of both a systemic and a compartmentalized response, independently of the presence of infection. Because cytokines can be trapped by the surrounding cells in their environment, measurable levels of cytokines in biologic fluids represent the "tip of the iceberg," which is not the case for soluble receptors. The correlations of these latter markers between plasma and pleura strongly suggest that exchanges between both compartments can occur in both directions.