[Is it really an acute respiratory distress syndrome? : Current definitions, pathophysiology and differentiated diagnoses]. / Ist es wirklich ein akutes Lungenversagen? : Aktuelle Definitionen, Pathophysiologie und Differentialdiagnosen.

Although the Berlin definition of the acute respiratory distress syndrome (ARDS) is generally recognized, the differentiation from other diseases with severe gas exchange disturbances is often difficult in clinical practice. In particular, the assessment of radiological findings and identification of primary noncardiogenic lung edema pose problems. In ARDS typical inflammatory processes can be found with involvement of activated neutrophilic granulocytes. Anti-inflammatory treatment strategies were unsuccessful. Lung protective ventilation strategies and prone positioning are the only evidence-based treatment options. Identifying ARDS phenotypes according to the etiology or disease progression can possibly provide a targeted individualized treatment option. The control of various biomarkers for assessment and treatment is the main focus of scientific interest. The results of appropriate studies remain to be seen.

[Ventilation in acute respiratory distress. Lung-protective strategies]. / Beatmung beim akuten Lungenversagen. Lungenprotektive Strategien.

Ventilation of patients suffering from acute respiratory distress syndrome (ARDS) with protective ventilator settings is the standard in patient care. Besides the reduction of tidal volumes, the adjustment of a case-related positive end-expiratory pressure and preservation of spontaneous breathing activity at least 48 h after onset is part of this strategy. Bedside techniques have been developed to adapt ventilatory settings to the individual patient and the different stages of ARDS. This article reviews the pathophysiology of ARDS and ventilator-induced lung injury and presents current evidence-based strategies for ventilator settings in ARDS.

[Positive end-expiratory pressure : adjustment in acute lung injury]. / Positiver endexspiratorischer Druck : Einstellung bei respiratorischer Insuffizienz.

Treatment of patients suffering from acute lung injury is a challenge for the treating physician. In recent years ventilation of patients with acute hypoxic lung injury has changed fundamentally. Besides the use of low tidal volumes, the most beneficial setting of positive end-expiratory pressure (PEEP) has been in the focus of researchers. The findings allow adaption of treatment to milder forms of acute lung injury and severe forms. Additionally computed tomography techniques to assess the pulmonary situation and recruitment potential as well as bed-side techniques to adjust PEEP on the ward have been modified and improved. This review gives an outline of recent developments in PEEP adjustment for patients suffering from acute hypoxic and hypercapnic lung injury and explains the fundamental pathophysiology necessary as a basis for correct treatment.

Impact of early vs. late tracheostomy on weaning: a retrospective analysis.

BACKGROUND: Early tracheostomy has been advocated for a number of reasons. Especially in association with weaning from mechanical ventilation, it is known that an early timepoint can help patients being weaned more rapidly from the ventilator. However, timing of tracheostomy is still unknown and evidence is lacking. The effects of early tracheostomy compared with intermediate and late tracheostomy were assessed in critically ill patients. METHODS: Data collected from January 2005 to December 2007 were conducted for retrospective analysis. All patients needing tracheostomy due to extubation failure and/or weaning failure were included (N.=296). Early tracheostomy (ET) was defined as ≤4 days, intermediate tracheostomy (IT) as tracheostomy within 5-9 days, and late tracheostomy (LT) was defined as ≥10 days after endotracheal intubation. After proving normal distribution, significant changes between the three groups were tested by ANOVA followed by post hoc tests for multiple comparisons (Bonferroni's test). RESULTS: Intensive care unit (ICU) mortality was significantly higher in the LT group when being compared with the ET but not when being compared with the IT group (40.7% vs. 24.8% vs. 17.1%). Further, a significantly reduced incidence of VAP and sepsis, a smaller amount of ventilator days and a shorter ICU length of stay could be observed for the ET group. Length of weaning was not significantly different between the groups. CONCLUSION: The length of weaning after tracheostomy is not affected by the timing. It seems beneficial to favour early tracheostomy in order to reduce the time of mechanical ventilation and its associated risks.

Outcome and mortality risk factors in long-term treated ICU patients: a retrospective analysis.

BACKGROUND: Little is known about the prognosis and outcome of critically ill patients with a prolonged length of stay (LOS). The aim of this study was to examine mortality and its risk factors in patients requiring intensive care therapy for more than 30 days. METHODS: A retrospective, single-center analysis of data collected in a surgical intensive care unit (ICU) of a university hospital in Germany from 2005 to 2007 was conducted. All demographic data and clinical variables were collected. A univariate analysis followed by multivariate regression was performed to detect the relevant risk factors for short and long-term mortality. RESULTS: Altogether, 10 737 patients were admitted to the ICU; 136 patients fulfilled the criteria for long-term treatment, 75% (N=102) of whom were discharged from ICU. The one-year survival rate was 61.8% (N=60). The most significant risk factors were pulmonary compromise with prolonged mechanical ventilation and infectious disorders leading to sepsis. However, sepsis was not a predictor of outcome. Weaning failure was present in 67.6% (N=92) at day 30 but was reduced to 37.5% of the cases (N=51) over the total course of the stay. Acute and long-term prognoses were determined by a successful weaning. CONCLUSION: Although the long-term treatment of critically ill patients requires significant effort, the outcome for this particular cohort was reasonably favorable. Prolonged mechanical ventilation and weaning are the factors that influence mortality independently of sepsis. Because reasonable improvements can be shown even after a prolonged LOS, further attention should be paid to weaning processes.

Harrahill's technique: a simple screening test for intra-abdominal pressure measurement.

BACKGROUND: Repair of giant incisional hernias may lead to an increase in intra-abdominal pressure (IAP) and, sometimes, to abdominal compartment syndrome. Measurement of IAP using Kron's technique (Kron et al. in Ann Surg 199:28-30, 1984) is currently accepted as the gold standard, whereas Harrahill has described a simple measurement setup using urinary drainage manometry (Harrahill in J Emerg Nurs 24:465-466, 1998). The aim of this clinical trail was to evaluate the correlation, reproducibility and effectiveness of this device. METHODS: A prospective cohort study was performed in 43 patients undergoing elective standard abdominal intervention with laparotomy. These patients remain under surveillance in the intensive care unit and require a urinary catheter because of the operation. We performed comparative measurements of IAP using both Korn's (IVM) and Harrahill's (UDM) technique. RESULTS: Evaluating the correlation between the IVM and UDM techniques, we measured median IAPs of 9.8 +/- 4.1 mmHg (2.9-19.9 mmHg) and 10.0 +/- 4.1 mmHg (min-max: 1.5-19.9 mmHg), respectively. Pearson's coefficient of correlation was r = 0.97. The average of difference between UDM and IVM was -0.2 +/- 0.9 mmHg with limits of agreement of -1.7 to 2.0 mmHg. Evaluating the reproducibility of Harrahill's technique, we found median IAPs of 10.4 +/- 2.1 mmHg (min-max: 2.9-19.1 mmHg) and 10.4 +/- 2.7 mmHg (3.7-19.9 mmHg), respectively, in 43 comparative measurements (Pearson's coefficient of correlation, r = 0.97. The average difference between both measurements was -0.1 +/- 1.1 mmHg with limits of agreement of -2.3 to 2.2 mmHg. CONCLUSIONS: We were able to demonstrate good correlation and high reproducibility of IAP measurement using Harrahill's technique compared to the gold standard Korn method. We consider this technique as a suitable method for quick and simple screening test for intra-abdominal hypertension, especially after repair of giant incisional hernias.

[Intensive care medicine as a component of the compulsory medical curriculum. Evaluation of a pilot curriculum at the University Hospital Aachen]. / Intensivmedizin als Bestandteil des Pflicht-Curriculums: Evaluation eines Pilot-Curriculums am Universitätsklinikum Aachen.

BACKGROUND: In order to provide early achievement of practical experience during medical education, the medical faculty of the university Aachen has developed a new medical school curriculum which was offered in 2003 for the first time. In this curriculum anaesthesiology became a compulsory subject with practical training both in the operation theatre and in emergency medicine. Accordingly, a practical course in the field of intensive care medicine has also been designed with respect to the planned schedule and personnel resources. This course was evaluated by both students and teaching staff in a written, anonymous form as a quality control. METHODS: A dedicated course was developed for medical students of the 8th and 9th semesters. In this course comprised of 6 students and lasting 1 week, practical training is provided by intensive care physicians and accompanied by theoretical lessons focusing on the definition, diagnosis, therapy and prophylaxis of sepsis, essentials of mechanical ventilation and patient presentation at the bedside during daily rounds. On the last day of training students were required to present patients by themselves thereby recapitulating the acquired knowledge. In the summer semester 2007 this intensive care training course was offered for the first time. All participating 83 students and 23 physicians involved in teaching evaluated the course with marks from 1 to 6 according to the standard German school grading system using an online questionnaire. RESULTS: Students rated the course with 1.6+/-0.7 (mean +/- SD) for comprehensibility, with 1.6+/-0.7 for structural design, and with 1.7+/-0.7 for agreement between teachers. They graded their personal learning success with 1.7+/-0.7. With a cumulative mark of 1.7+/-0.6, the course was ranked as 1 of the top 3 courses of the medical faculty from the very beginning. The majority of the teaching staff (80%) appreciated the focus on few selected teaching subjects. However, comprehensibility, structural design, agreement between teachers and personal learning success were graded one mark worse than by the students. CONCLUSIONS: According to the results, efficiency and acceptance of intensive care training courses were high. Major criteria for the high grading were a limited number of participants, the focus on few subjects, and a clear structural design. However, according to several personal notes from the students, simulation-based sessions and written teaching material might further improve success of this course.

[Ventilator-associated pneumonia]. / Ventilatorassoziierte Pneumonie.

Ventilator-associated pneumonia (VAP) is the most common nosocomial infection in critical care medicine and has been shown to be an independent risk factor for mortality. However, ventilator induced lung injury itself is probably only a minor factor predisposing to VAP. In contrast, invasive ventilation using an endotracheal tube is obviously a more important measure. Thus, microaspiration of potentially infectious secretion from the oropharynx into the trachea along the tube has been suggested to be the most critical pathophysiological event in the process of VAP development. Accordingly, non-invasive ventilation provides a decreased risk of VAP. Therefore, all measures aimed at averting microaspiration or shorten the duration of mechanical ventilation are appropriate to prevent VAP. Moreover, oropharyngeal decontamination may be helpful by reducing bacterial colonisation. Effectiveness of therapy depends on early treatment and therefore requires early diagnosis. With this aim combined clinical, radiologic, and microbiological parameters should be taken into account. Adequate antimicrobial therapy in due consideration for individual risk factors and local antibiotic resistance is the most important therapeutic measure.

[Mechanical ventilation of acute lung injury]. / Beatmung beim akuten Lungenversagen.

Acute lung injury (ALI) is of paramount importance for modern intensive care since it is one of the most frequent conditions necessitating admission to an ICU. ALI is characterised by severe life threatening hypoxemia which is based on ventilation perfusion mismatching within the lung. This is mostly resulting from atelectasis formation due to primary or secondary inflammation of lung tissue. Many studies showed that this inflammatory process is not restricted to the respiratory system but might result in non pulmonary organ failure and hemodynamic compromise as well. Mechanical ventilation is considered the hallmark treatment for ALI patients aimed to recruit lung tissue and thereby reverse hypoxemia without causing additional lung injury potentially resulting from overdistention or cycling collapse during expiration. Scientific evidence shows us that prevention of ventilator induced lung injury by protective ventilation with reduced tidal volumes is resulting in better clinical outcomes. Moreover, different technologies and adjunctive therapies have been suggested based on their pathophysiology. All these treatment options will be summarized in this article. Given the clear evidence for protective ventilation and bearing in mind that clinical application of this easy concept is still not widespread we will focus on this aspect.

Role of extracorporeal lung assist in the treatment of acute respiratory failure.

For patients with most severe acute respiratory distress syndrome (ARDS) conservative treatment with lung protective ventilation is often not sufficient to prevent life-threatening hypoxemia and additional strategies are necessary. Extracorporeal lung assist (ECLA) or extracorporeal membrane oxygenation (ECMO) using capillary membrane oxygenators can provide sufficient gas exchange and lung rest. In 2 randomized trials mortality was unchanged for ECMO. Today an technically enhanced ECMO is used for most severe ARDS using clinical algorithm and different case studies demonstrated a survival rate about 56%. Today miniaturized ECMO with optimized blood pumps and oxygenators are available and could enhance safety and clinical management. Another approach is an arterio-venous pumpless interventional lung assist (ILA) with a low resistance oxygenator. Advantages seem a simplified clinical management and less blood trauma. At present new devices are developed for chronic respiratory failure or bridge to lung transplant. Oxygenators with even less flow resistance could be implanted paracorporeal using the right ventricle as driving force. An intravascular oxygenator has been developed using the combination of a miniaturized blood pump and an oxygenator for implantation in the vena cava. Well designed clinical trials are necessary to demonstrate a clinical benefit for these experimental devices.

[Pulmonary hypertension]. / Pulmonale Hypertonie.

Pulmonary hypertension can arise in the presence of acute cardiopulmonary decompensation or develop as a chronic and progressive disease in association with connective tissue diseases, infectious diseases, or metabolic diseases, or in the form of idiopathic pulmonary hypertension. Impaired regulation of endogenous vasoactive mediators, growth factors, and thrombotic factors leads to pulmonary artery vasoconstriction, endothelial and epithelial proliferation, and thrombotic vascular obstruction, with resulting right heart failure. There is no curative treatment for chronic pulmonary hypertension, and the immediate objective of palliative treatment is to relieve right heart stress by reducing pulmonary arterial pressure with the aid of pulmonary vasodilators. Depending on the severity of the illness, perioperative mortality is high, which must be borne in mind by both anesthetists and intensivists. Chronic medical treatment for these patients must be optimized before any surgery is undertaken. In the perioperative period, it is essential that anything that could lead to worsening of pulmonary hypertension is avoided, or at least recognized and treated at an early stage. Intraoperatively, imminent acute right heart decompensation is treated by improving right-ventricular contractility and reducing right-ventricular afterload. In the postoperative period, monitoring and optimization of the cardiopulmonary status, adequate analgesia and sedation, and careful anticoagulation must be ensured.

Artificial lung and extracorporeal gas exchange.

Over the last years, several observational studies have suggested that extracorporeal lung assist (ECLA) may be an important contribution to clinical algorithms for the treatment of most severe acute respiratory distress syndrome (ARDS). Today ECLA is used only as a rescue therapy in life threatening gas exchange disorders if maximal conventional therapy fails to prevent from hypoxemia. With subsequent reduction of complications and improvement of biocompability, extracorporeal membrane oxygentation (ECMO) indications may be extendend to treat patients earlier and not only in rescue situations along the original idea to buy the lung some time to heal by avoiding further ventilator associated lung injury. Veno-venous ECMO therapy at present is an important therapeutic option in severe ARDS with persisiting life threatening gas exchange disorder as a rescue therapy. The development of smaller, less complex and more secure ECMO or pumpless veno-arterial ECLA systems has the potential to perform controlled studies of its use in ARDS and potentially expand indications.

Cardiopulmonary effects of iloprost in experimental acute lung injury.

Iloprost, a prostacyclin analogue with a prolonged plasma half-life has beneficial effects in chronic pulmonary hypertension, whereas the effects in acute lung injury (ALI) are unknown. The present study was performed to evaluate the cardiopulmonary effects of iloprost in experimental ALI. ALI was induced in 18 pigs by repeated lung lavage. Animals were randomised to controls, i.v. or inhaled iloprost for 15 min. Haemodynamics, gas exchange and ventilation-perfusion distribution were measured at the end of iloprost application and after 1 and 2 h. As a short-term effect, both i.v. and inhaled iloprost significantly decreased pulmonary artery pressure without major effects on gas exchange or systemic haemodynamics. After 1 and 2 h, a reduction of pulmonary hypertension was no longer present. As a long-term effect, inhaled, but not i.v., iloprost decreased pulmonary shunt and significantly improved gas exchange after 1 and 2 h. In conclusion, the single application of iloprost revealed short-term pulmonary vasodilation without other major cardiopulmonary effects. However, inhaled iloprost improved gas exchange due to a decrease of pulmonary shunt as a long-term effect, possibly as a result of a reduction of lung oedema formation.

Modulating the pulmonary circulation: an update.

Pulmonary hypertension is a common finding in pulmonary circulatory disorders of different origin. Chronic pulmonary hypertension may develop due to either cardiopulmonary or systemic diseases whereas acute and acute-on-chronic pulmonary hypertension often occur in the course of cardiothoracic surgery. Right heart failure is the major risk particularly in the course of acute pulmonary hypertension. Thus, besides basic treatment of the underlying disease the use of vasodilators is a valuable therapeutic option to decrease right ventricular afterload, but intravenous vasodilators may provoke systemic arterial hypotension and impair gas exchange due to vasodilation of pulmonary shunt areas. Therefore, inhaled vasodilators such as nitric oxide and prostacyclin have been suggested for the treatment of pulmonary hypertension especially when concomitant hypoxemia is present due to a ventilation-perfusion mismatch. However, randomised controlled trials performed to evaluate long-term effects revealed different results: thus, in chronic pulmonary hypertension inhaled vasodilators improved outcome whereas the results for the treatment of the acute respiratory distress syndrome revealed beneficial effects only when used as a rescue and/or bridging therapy in severe hypoxemia. In cardiothoracic surgery, inhaled vasodilators have been shown to improve pulmonary circulation when severe pulmonary hypertension is present. Although effective in experimental studies no clear recommendation can be made in view to the use of other vasodilators such as phosphodiesterase inhibitors or endothelin antagonists. Likewise, the combination of different vasodilators merit further investigations to prove efficacy in randomised controlled trials.

Anesthetic considerations in patients with chronic pulmonary diseases.

AIM: Increasing age and co-morbidities of patients admitted for surgery impose new challenges on the anesthesiologist. METHODS: Review of current literature regarding the perioperative management of patients with chronic pulmonary disease. RESULTS: If patients are treated adequately, surgery can be safely performed under regional and general anaesthesia. Major risk factors include type of surgery, type and duration of anesthesia, general health status and smoking history, but not certain lung function parameters. Regional anesthesia remains the first choice for intra- and postoperative care, and if general anesthesia is necessary, early extubation should be achieved. Non-invasive ventilation could be a possible alternative in weaning failure. CONCLUSION: Assessing the functional status of patients admitted to surgery remains a difficult task, and in patients identified at risk by clinical examination additional spirometry and blood gases may be helpful. If there are signs of respiratory failure, the anaesthetist should monitor the patient closely and invasively, yet there is no reason to deny any patient a substantially beneficial operation.

[Extracorporeal membrane oxygenation by acute respiratory distress syndrome]. / Extrakorporale Membranoxygenierung beim akuten Lungenversagen.

After various observational studies demonstrated a benefit of extracorporeal membrane oxygenation (ECMO) in the therapy of severe acute respiratory distress syndrome (ARDS), ECMO now represents an important contribution for ARDS therapy using clinical algorithms despite a lack of positive controlled studies. In specialized centers patients with severe ARDS and imminent hypoxia despite intensive conventional therapy, are treated with ECMO using blood pumps and artificial membrane lungs (oxygenators) for extracorporeal lung assist. The development of new surface modifications, optimized oxygenators and miniaturized blood pumps should increase hemocompatibility and lead to simplified treatment as well as less complications. New oxygenators with significantly decreased blood resistance allow the clinical application of pumpless arteriovenous extracorporeal lung assist (ECLA). After these new developments indications for ECMO could be extended from use not only as ultimate ratio but to less severe ARDS to enable lung protective, less invasive mechanical ventilation.

[Treatment of acute respiratory distress syndrome in a treatment center. Success is dependent on risk factors]. / Therapie des akuten Lungenversagens in einem Behandlungszentrum. Der Erfolg ist abhängig von der Indikationsstellung.

SUBJECT: Mortality rates remain high for the acute respiratory distress syndrome (ARDS) despite standardised treatment algorithms. Little is known about prognostic factors and exclusion criteria for advanced treatment including extracorporeal membrane oxygenation (ECMO). METHODS: In an observational study design a cohort of 93 patients with severe ARDS admitted to a referral centre were analysed according to ventilatory and vital parameters. RESULTS: Overall survival rate was 70% and in patients who received ECMO treatment it was 67%. In patients exhibiting relevant co-morbidity the odds ratio for fatal outcome increased to 4.7 (95% CI: 3.3-24.9), and patients with multiple organ failure had a 7.5-fold increase (95% CI: 2.3-25.2) for risk of death. Survivors demonstrated a more pronounced improvement in oxygenation ( p<0.05) and CO(2) removal ( p<0.05) than non-survivors. CONCLUSIONS: Advanced treatment of ARDS including ECMO represents a therapeutic option if none of the currently considered contraindications are present. An improvement in gas exchange parameters, but not a defined value per se may be useful as a prognostic factor for favourable outcome.