Identification and analysis of stable breathing periods in electrical impedance tomography recordings

Objective. In this paper, an automated stable tidal breathing period (STBP) identification method based on processing electrical impedance tomography (EIT) waveforms is proposed and the possibility of detecting and identifying such periods using EIT waveforms is analyzed. In wearable chest EIT, patients breathe spontaneously, and therefore, their breathing pattern might not be stable. Since most of the EIT feature extraction methods are applied to STBPs, this renders their automatic identification of central importance.Approach. The EIT frame sequence is reconstructed from the raw EIT recordings and the raw global impedance waveform (GIW) is computed. Next, the respiratory component of the raw GIW is extracted and processed for the automatic respiratory cycle (breath) extraction and their subsequent grouping into STBPs.Main results. We suggest three criteria for the identification of STBPs, namely, the coefficient of variation of (i) breath tidal volume, (ii) breath duration and (iii) end-expiratory impedance. The total number of true STBPs identified by the proposed method was 294 out of 318 identified by the expert corresponding to accuracy over 90%. Specific activities such as speaking, eating and arm elevation are identified as sources of false positives and their discrimination is discussed.Significance. Simple and computationally efficient STBP detection and identification is a highly desirable component in the EIT processing pipeline. Our study implies that it is feasible, however, the determination of its limits is necessary in order to consider the implementation of more advanced and computationally demanding approaches such as deep learning and fusion with data from other wearable sensors such as accelerometers and microphones.

Regional lung function measures determined by electrical impedance tomography during repetitive ventilation manoeuvres in patients with COPD

OBJECTIVE

Current standards for conducting spirometry examinations recommend that the ventilation manoeuvres needed in pulmonary function testing are carried out repeatedly during sessions. Chest electrical impedance tomography (EIT) can determine the presence of ventilation heterogeneity during such manoeuvres, which increases the information content derived from such examinations. The aim of this study was to characterise regional lung function in patients with chronic obstructive pulmonary disease (COPD) during repetitive forced full ventilation manoeuvres. Regional lung function measures derived from these manoeuvres were compared with quiet tidal breathing.

APPROACH

Sixty hospitalised patients were examined during up to three repeated ventilation manoeuvres. Acceptable spirometry manoeuvres were performed and EIT recordings suitable for analysis obtained in 53 patients (12 women, 41 men; age: 68 ± 12 years (mean ± SD)). Pixel values of tidal volume, forced full inspiratory and expiratory volume in 1 s, and forced inspiratory and expiratory vital capacity were calculated from the EIT data. Spatial ventilation heterogeneity was assessed using the coefficient of variation, global inhomogeneity index, and centres and regional fractions of ventilation. Temporal inhomogeneity was determined by examining the pixel expiration times needed to exhale 50% and 75% of regional forced vital capacity.

MAIN RESULTS

All EIT-derived measures of regional lung function showed reproducible results during repetitive examinations. Parameters of spatial heterogeneity obtained from quiet tidal breathing were comparable with the measures derived from the forced manoeuvres.

SIGNIFICANCE

Measures of spatial and temporal ventilation heterogeneity obtained in COPD patients by EIT provide comparable findings during repeated examinations within one testing session. Quiet tidal breathing generates similar information on ventilation heterogeneity as forced manoeuvres that demand a high amount of patient effort.

The Impact of Immersion on Cluster Identification Tasks

Recent developments in technology encourage the use of head-mounted displays (HMDs) as a medium to explore visualizations in virtual realities (VRs). VR environments (VREs) enable new, more immersive visualization design spaces compared to traditional computer screens. Previous studies in different domains, such as medicine, psychology, and geology, report a positive effect of immersion, e.g., on learning performance or phobia treatment effectiveness. Our work presented in this paper assesses the applicability of those findings to a common task from the information visualization (InfoVis) domain. We conducted a quantitative user study to investigate the impact of immersion on cluster identification tasks in scatterplot visualizations. The main experiment was carried out with 18 participants in a within-subjects setting using four different visualizations, (1) a 2D scatterplot matrix on a screen, (2) a 3D scatterplot on a screen, (3) a 3D scatterplot miniature in a VRE and (4) a fully immersive 3D scatterplot in a VRE. The four visualization design spaces vary in their level of immersion, as shown in a supplementary study. The results of our main study indicate that task performance differs between the investigated visualization design spaces in terms of accuracy, efficiency, memorability, sense of orientation, and user preference. In particular, the 2D visualization on the screen performed worse compared to the 3D visualizations with regard to the measured variables. The study shows that an increased level of immersion can be a substantial benefit in the context of 3D data and cluster detection.

Current clinical use of intravenous fosfomycin in ICU patients in two European countries

PURPOSE

In Europe, intravenous fosfomycin (IV) is used particularly in difficult-to-treat or complex infections, caused by both Gram-positive and Gram-negative pathogens including multidrug-resistant strains. Here, we investigated the efficacy and safety of intravenous fosfomycin under real-life conditions.

METHODS

Prospective, multi-center, and non-interventional study in patients with bacterial infections from 20 intensive care units (ICU) in Germany and Austria (NCT01173575).

RESULTS

Overall, 209 patients were included (77 females, 132 males, mean age: 59 ± 16 years), 194 of which were treated in intensive care (APACHE II score at the beginning of fosfomycin therapy: 23 ± 8). Main indications (± bacteremia or sepsis) were infections of the CNS (21.5%), community- (CAP) and hospital-acquired pneumonia (HAP)/ventilator-associated pneumonia (VAP, 15.3%), bone and joint infections (BJI, 11%), abdominal infections (11%), and bacteremia (10.5%). Most frequently identified pathogens were S. aureus (22.3%), S. epidermidis (14.2%), Enterococcus spp. (10.8%), E. coli (12.3%) and Klebsiella spp. (7.7%). At least one multidrug-resistant (MDR) pathogen was isolated from 51 patients (24.4%). Fosfomycin was administered with an average daily dose of 13.7 ± 3.5 g over 12.4 ± 8.6 days, almost exclusively (99%) in combination with other antibiotics. The overall clinical success was favorable in 81.3% (148/182) of cases, and in 84.8% (39/46) of patients with ≥ 1 MDR pathogen. Noteworthy, 16.3% (34/209) of patients developed at least one, in the majority of cases non-serious, adverse drug reaction during fosfomycin therapy.

CONCLUSION

Our data suggest that IV fosfomycin is an effective and safe combination partner for the treatment of a broad spectrum of severe bacterial infections in critically ill patients.

No evidence of hepatitis B virus reactivation in patients with resolved infection treated with direct-acting antivirals for hepatitis C in a large real-world cohort

BACKGROUND

Hepatitis B virus (HBV) reactivation has been observed following interferon (IFN)-based treatment in HBV/hepatitis C virus (HCV) co-infected patients. Recent reports suggest that reactivation may also occur in both hepatitis B surface antigen (HBsAg)-positive and HBsAg-negative patients during HCV treatment with direct-acting antivirals (DAAs).

AIM

To investigate the rate of patients with HBV reactivation during IFN-based and IFN-free HCV treatment in a large real-world cohort.

METHODS

A total of 848 patients with chronic hepatitis C were treated with different combinations of DAAs. Among patients with available outcome and HBV data, there were 272 patients hepatitis B core antibody (HBcAb)-positive (HBsAg-positive, n=9; HBsAg-negative, n=263), and 536 were HBcAb-negative. All HBcAb-positive patients were tested for HBV DNA at the end of DAA therapy and alanine transaminase (ALT) levels were frequently measured during therapy and follow-up.

RESULTS

Seventy-three percent (n=192/263) of HBsAg-negative/HBcAb-positive patients had elevated ALT levels at baseline, which declined to normal values in all but 18 patients, and no HBV reactivation was observed. Eight patients had detectable but not quantifiable HBV DNA (<20 IU/mL) at end of treatment, but none were associated with elevated ALT. Five of nine HBsAg-positive/HBcAb-positive patients experienced transient or permanent HBV reactivation, three of whom required nucleos(t)ide treatment during (n=1) or after (n=2) DAA therapy.

CONCLUSIONS

HBV reactivation was not observed in HBsAg-negative/HBcAb-positive patients but common in HBsAg-positive/HBcAb-positive patients treated with different combinations of DAAs for HCV.

Global and regional assessment of sustained inflation pressure-volume curves in patients with acute respiratory distress syndrome

OBJECTIVE

Static or quasi-static pressure-volume (P-V ) curves can be used to determine the lung mechanical properties of patients suffering from acute respiratory distress syndrome (ARDS). According to the traditional interpretation, lung recruitment occurs mainly below the lower point of maximum curvature (LPMC) of the inflation P-V curve. Although some studies have questioned this assumption, setting of positive end-expiratory pressure 2 cmH₂O above the LPMC was part of a 'lung-protective' ventilation strategy successfully applied in several clinical trials. The aim of our study was to quantify the amount of unrecruited lung at different clinically relevant points of the P-V curve.

APPROACH

P-V curves and electrical impedance tomography (EIT) data from 30 ARDS patients were analysed. We determined the regional opening pressures for every EIT image pixel and fitted the global P-V curves to five sigmoid model equations to determine the LPMC, inflection point (IP) and upper point of maximal curvature (UPMC). Points of maximal curvature and IP were compared between the models by one-way analysis of variance (ANOVA). The percentages of lung pixels remaining closed ('unrecruited lung') at LPMC, IP and UPMC were calculated from the number of lung pixels exhibiting regional opening pressures higher than LPMC, IP and UPMC and were also compared by one-way ANOVA.

MAIN RESULTS

As results, we found a high variability of LPMC values among the models, a smaller variability of IP and UPMC values. We found a high percentage of unrecruited lung at LPMC, a small percentage of unrecruited lung at IP and no unrecruited lung at UPMC.

SIGNIFICANCE

Our results confirm the notion of ongoing lung recruitment at pressure levels above LPMC for all investigated model equations and highlight the importance of a regional assessment of lung recruitment in patients with ARDS.

[Health-related quality of life after mechanical ventilation in the intensive care unit]

BACKGROUND

It is unknown whether health related quality of life measured in German patients one year after mechanical ventilation in the intensive care unit is impaired or not.

OBJECTIVES

The aim of this study was to assess health related quality of life one year after inclusion into a randomized controlled trial for weaning from mechanical ventilation with the help of a questionnaire that has never been used in critically ill patients and to investigate whether health related quality of life scores differ between the study population and a general German population.

METHODS

We followed up with patients one year after inclusion into a randomized control trial investigating the effect of SmartCare/PS on total ventilation time compared to protocol-driven weaning (ASOPI trial, clinicaltrials.gov ID00445289). Health related quality of life was measured using the quality of life questionnaire C‑30 version 3.0 from the European Organization of Research and Treatment of Cancer (EORTC). Mean differences of at least 10 score points in the quality of life scales were considered clinically significant.

RESULTS

Of the 232 patients who were alive 90 days after study inclusion, 24 patients died one year after study inclusion and 64 patients were lost to follow-up. Of the remaining145 patients who were successfully contacted, 126 patients agreed to fill out the questionnaire. Questionnaires were sent back to the study site by 83 patients and these were analyzed. Health-related quality of life was significantly lower in five of the six functional scales (physical functioning, role functioning, cognitive functioning, social functioning, global health status) and in eight of the nine symptom scales (fatigue, pain, dyspnea, insomnia, appetite loss, constipation, diarrhea, financial difficulties) compared to the reference values of a German normal population.

CONCLUSIONS

The EORTC QLQ-C30 questionnaire is suitable for the acquisition of the health-related quality of life in formerly critically ill patients. Health-related quality of life is severely impaired after mechanical ventilation in the intensive care unit. Future studies should consider health related quality of life as a possible study endpoint.

The efficacy and safety of direct acting antiviral treatment and clinical significance of drug-drug interactions in elderly patients with chronic hepatitis C virus infection

BACKGROUND

Direct antiviral therapies for chronic hepatitis C virus (HCV) infection have expanded treatment options for neglected patient populations, including elderly patients who are ineligible/intolerant to receive interferon (IFN)-based therapy.

AIM

To investigate the efficacy, tolerability and potential for drug-drug interactions (DDIs) of IFN-free treatment in patients aged ≥65 years in a large real-world cohort.

METHODS

A total of 541 patients were treated with different combinations of direct antiviral agents (DAAs: ledipasvir/sofosbuvir ±ribavirin; daclatasvir/sofosbuvir ±ribavirin; paritaprevir/ombitasvir ±dasabuvir ±ribavirin or simeprevir/sofosbuvir ±ribavirin in genotype 1/4, and daclatasvir/sofosbuvir ±ribavirin or sofosbuvir/ribavirin in genotype 2/3). Efficacy, safety and potential DDIs were analysed and compared between patients aged <65 years (n = 404) and patients aged ≥65 years (n = 137) of whom 41 patients were ≥75 years.

RESULTS

Sustained virological response rates were 98% and 91% in patients aged ≥65 years and <65 years, respectively. Elderly patients took significantly more concomitant medications (79% vs. 51%; P < 0.0001). The number of concomitant drugs per patient was highest in patients ≥65 years with cirrhosis (median, three per patient; range, 0-10). Based on the hep-druginteractions database, the proportion of predicted clinically significant DDIs was significantly higher in elderly patients (54% vs. 28%; P < 0.0001). The number of patients who experienced treatment-associated adverse events was similar between the two age groups (63% vs. 65%; P = n.s.).

CONCLUSIONS

Elderly patients are at increased risk for significant DDIs when treated with DAAs for chronic HCV infection. However, with careful pre-treatment assessment of concomitant medications, on-treatment monitoring or dose-modifications, significant DDIs and associated adverse events can be avoided.

Influence of torso and arm positions on chest examinations by electrical impedance tomography

Electrical impedance tomography (EIT) is increasingly used in patients suffering from respiratory disorders during pulmonary function testing (PFT). The EIT chest examinations often take place simultaneously to conventional PFT during which the patients involuntarily move in order to facilitate their breathing. Since the influence of torso and arm movements on EIT chest examinations is unknown, we studied this effect in 13 healthy subjects (37  ±  4 years, mean age  ±  SD) and 15 patients with obstructive lung diseases (72  ±  8 years) during stable tidal breathing. We carried out the examinations in an upright sitting position with both arms adducted, in a leaning forward position and in an upright sitting position with consecutive right and left arm elevations. We analysed the differences in EIT-derived regional end-expiratory impedance values, tidal impedance variations and their spatial distributions during all successive study phases. Both the torso and the arm movements had a highly significant influence on the end-expiratory impedance values in the healthy subjects (p  =  0.0054 and p  <  0.0001, respectively) and the patients (p  <  0.0001 in both cases). The global tidal impedance variation was affected by the torso, but not the arm movements in both study groups (p  =  0.0447 and p  =  0.0418, respectively). The spatial heterogeneity of the tidal ventilation distribution was slightly influenced by the alteration of the torso position only in the patients (p  =  0.0391). The arm movements did not impact the ventilation distribution in either study group. In summary, the forward torso movement and the arms' abduction exert significant effects on the EIT waveforms during tidal breathing. We recommend strict adherence to the upright sitting position during PFT when EIT is used.

Regional lung function determined by electrical impedance tomography during bronchodilator reversibility testing in patients with asthma

The measurement of rapid regional lung volume changes by electrical impedance tomography (EIT) could determine regional lung function in patients with obstructive lung diseases during pulmonary function testing (PFT). EIT examinations carried out before and after bronchodilator reversibility testing could detect the presence of spatial and temporal ventilation heterogeneities and analyse their changes in response to inhaled bronchodilator on the regional level. We examined seven patients suffering from chronic asthma (49  ±  19 years, mean age  ±  SD) using EIT at a scan rate of 33 images s(-1) during tidal breathing and PFT with forced full expiration. The patients were studied before and 5, 10 and 20 min after bronchodilator inhalation. Seven age- and sex-matched human subjects with no lung disease history served as a control study group. The spatial heterogeneity of lung function measures was quantified by the global inhomogeneity indices calculated from the pixel values of tidal volume, forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak flow and forced expiratory flow between 25% and 75% of FVC as well as histograms of pixel FEV1/FVC values. Temporal heterogeneity was assessed using the pixel values of expiration times needed to exhale 75% and 90% of pixel FVC. Regional lung function was more homogeneous in the healthy subjects than in the patients with asthma. Spatial and temporal ventilation distribution improved in the patients with asthma after the bronchodilator administration as evidenced mainly by the histograms of pixel FEV1/FVC values and pixel expiration times. The examination of regional lung function using EIT enables the assessment of spatial and temporal heterogeneity of ventilation distribution during bronchodilator reversibility testing. EIT may become a new tool in PFT, allowing the estimation of the natural disease progression and therapy effects on the regional and not only global level.

Influence of tidal volume on ventilation inhomogeneity assessed by electrical impedance tomography during controlled mechanical ventilation

The global inhomogeneity (GI) index is a parameter of ventilation inhomogeneity that can be calculated from images of tidal ventilation distribution obtained by electrical impedance tomography (EIT). It has been suggested that the GI index may be useful for individual adjustment of positive end-expiratory pressure (PEEP) and for guidance of ventilator therapy. The aim of the present work was to assess the influence of tidal volume (VT) on the GI index values. EIT data from 9 patients with acute respiratory distress syndrome ventilated with a low and a high VT of 5   ±   1 (mean  ±  SD) and 9   ±   1 ml kg(-1) predicted body weight at a high and a low level of PEEP (PEEPhigh, PEEPlow) were analyzed. PEEPhigh and PEEPlow were set 2 cmH2O above and 5 cmH2O below the lower inflection point of a quasi-static pressure volume loop, respectively. The lower inflection point was identified at 8.1   ±   1.4 (mean  ±  SD) cmH2O, resulting in a PEEPhigh of 10.1   ±   1.4 and a PEEPlow of 3.1   ±   1.4 cmH2O. At PEEPhigh, we found no significant trend in GI index with low VT when compared to high VT (0.49   ±   0.15 versus 0.44   ±   0.09, p = 0.13). At PEEPlow, we found a significantly higher GI index with low VT compared to high VT (0.66   ±   0.19 versus 0.59   ±   0.17, p = 0.01). When comparing the PEEP levels, we found a significantly lower GI index at PEEPhigh both for high and low VT. We conclude that high VT may lead to a lower GI index, especially at low PEEP settings. This should be taken into account when using the GI index for individual adjustment of ventilator settings.

The wingless-related integration site-5a/secreted frizzled-related protein-5 system is dysregulated in human sepsis

Sepsis and type 2 diabetes exhibit insulin resistance as a common phenotype. In type 2 diabetes we and others have recently provided evidence that alterations of the proinflammatory wingless-related integration site (wnt)-5a/anti-inflammatory secreted frizzled-related protein (sFRP)-5 system are involved in the pathogenesis of insulin resistance. The aim of the present study was to investigate whether this novel cytokine system is dysregulated in human sepsis, which may indicate a potential mechanism linking inflammation to metabolism. In this single-centre prospective observational study, critically ill adult septic patients were examined and proinflammatory wnt5a and wnt5a inhibitor sFRP5 were measured in serum samples by enzyme-linked immunosorbent assay (ELISA) at admission to the intensive care unit (ICU) and 5 days later. Sixty sepsis patients were included, and 30 healthy individuals served as controls. Wnt5a levels were found to be increased significantly in septic patients compared to healthy controls (2·21 ± 0·33 versus 0·32 ± 0·03 ng/ml, P < 0·0001). In contrast, sFRP5 was not altered significantly in septic patients (19·72 ± 3·06 versus 17·48 ± 6·38 ng/ml, P = 0·07). On admission to the ICU, wnt5a levels exhibited a significant positive correlation with the leucocyte count (rs  = 0·3797, P = 0·004). Interestingly, in patients recovering from sepsis, wnt5a levels declined significantly within 5 days (2·17 ± 0·38-1·03 ± 0·28 ng/ml, P < 0·01). In contrast, if sepsis was worsening, wnt5a levels increased in the same time-period by trend (2·34 ± 0·59-3·25 ± 1·02 ng/ml, P > 0·05). sFRP5 levels did not change significantly throughout the study period. The wnt5a/sFRP5 system is altered in human sepsis and might therefore be of interest for future studies on molecular pathophysiology of this common human disease.

Tacrolimus effects and side effects after liver transplantation: is there a difference between immediate and extended release?

BACKGROUND

Immunosuppressive therapy after orthotopic liver transplantation (OLT) requires a high degree of patient compliance to guarantee safety and avoid side effects. In 2007, prolonged-release tacrolimus was launched in Europe to improve compliance. In this prospective observational crossover single-center trial, we analyzed effects and side effects of prolonged-release tacrolimus in OLT patients.

METHODS

LT patients at our center were included if they were older than l8 years of age, had had the procedure at least 6 months prior, and were outpatients currently on twice-daily tacrolimus. Patients were observed for 6 months before switching to once-daily tacrolimus. Patient history, clinical examination, and laboratory examinations were recorded on inclusion as well as after 3, 6, 9, 12, and 18 months.

RESULTS

The rates of rejection, hypertension, hypercholesterolemia, and diabetes mellitus were compared during twice-daily and once-daily tacrolimus. Similarly, laboratory parameters were identical during both periods with the exception of glycated hemoglobin, which was significantly elevated under once-daily tacrolimus (P = .00l).

CONCLUSION

Converting patients to extended-release tacrolimus with was safe in terms of rejection, hypertension, and hypercholesterolemia as well as renal and liver functions. Further investigations concerning pharmacokinetics and glucose metabolism will be needed to evaluate prolonged-release tacrolimus.

Pulmonary function testing in children and infants

Pulmonary function testing is performed in children and infants with the aim of documenting lung development with age and making diagnoses of lung diseases. In children and infants with an established lung disease, pulmonary function is tested to assess the disease progression and the efficacy of therapy. It is difficult to carry out the measurements in this age group without disturbances, so obtaining results of good quality and reproducibility is challenging. Young children are often uncooperative during the examinations. This is partly related to their young age but also due to the long testing duration and the unpopular equipment. We address a variety of examination techniques for lung function assessment in children and infants in this review. We describe the measuring principles, examination procedures, clinical findings and their interpretation, as well as advantages and limitations of these methods. The comparability between devices and centres as well as the availability of reference values are still considered a challenge in many of these techniques. In recent years, new technologies have emerged allowing the assessment of lung function not only on the global level but also on the regional level. This opens new possibilities for detecting regional lung function heterogeneity that might lead to a better understanding of respiratory pathophysiology in children.

Model-based setting of inspiratory pressure and respiratory rate in pressure-controlled ventilation

Mechanical ventilation carries the risk of ventilator-induced-lung-injury (VILI). To minimize the risk of VILI, ventilator settings should be adapted to the individual patient properties. Mathematical models of respiratory mechanics are able to capture the individual physiological condition and can be used to derive personalized ventilator settings. This paper presents model-based calculations of inspiration pressure (pI), inspiration and expiration time (tI, tE) in pressure-controlled ventilation (PCV) and a retrospective evaluation of its results in a group of mechanically ventilated patients. Incorporating the identified first order model of respiratory mechanics in the basic equation of alveolar ventilation yielded a nonlinear relation between ventilation parameters during PCV. Given this patient-specific relation, optimized settings in terms of minimal pI and adequate tE can be obtained. We then retrospectively analyzed data from 16 ICU patients with mixed pathologies, whose ventilation had been previously optimized by ICU physicians with the goal of minimization of inspiration pressure, and compared the algorithm's 'optimized' settings to the settings that had been chosen by the physicians. The presented algorithm visualizes the patient-specific relations between inspiration pressure and inspiration time. The algorithm's calculated results highly correlate to the physician's ventilation settings with r = 0.975 for the inspiration pressure, and r = 0.902 for the inspiration time. The nonlinear patient-specific relations of ventilation parameters become transparent and support the determination of individualized ventilator settings according to therapeutic goals. Thus, the algorithm is feasible for a variety of ventilated ICU patients and has the potential of improving lung-protective ventilation by minimizing inspiratory pressures and by helping to avoid the build-up of clinically significant intrinsic positive end-expiratory pressure.

Comparative analysis of in situ versus ex situ perfusion on micro circulation in liver procurement--an experimental trial in a porcine model

INTRODUCTION

The Achilles heel of liver transplantation remains the biliary system. The crucial step for liver preservation is effective rinsing and perfusion of the peribiliary plexus (PBP). Due to the physiology of the vascular tree, it seems almost impossible to achieve the necessary physiologic ranges of pressure and flow by the in situ perfusion technique. We investigated the role of additional ex situ perfusion via the hepatic artery in this animal model.

MATERIALS AND METHODS

Fifteen German Landrace pigs underwent standardized multiorgan procurement. In situ perfusion and additional ex situ perfusion were performed consecutively. Meanwhile the external pressure applied to the perfusion system was increased stepwise. To visualize the effects on the liver parenchyma and PBP, we administered colored microparticles (MPs; 10 μm). Frozen sections of the explanted liver were studied histologically by quantitative evaluation of the MPs.

RESULTS

Ex situ perfusion was able to build up significantly higher values of pressure (P < .001) and flow (P < .001) than in situ perfusion. Those of ex situ perfusion reached physiological levels under application of an external pressure of 200 mm Hg. Considering the liver parenchyma, significantly higher amounts of MPs originating from ex situ perfusion were evident (P < .001) and PBP (P < .001).

CONCLUSION

MPs provide an appropriate tool to determine organ perfusion quantitatively in experimental models. Considering flow, pressure, and microcirculation, we consider that additional ex situ perfusion of the liver is more effective than in situ perfusion.

[Change in therapy target and therapy limitations in intensive care medicine. Position paper of the Ethics Section of the German Interdisciplinary Association for Intensive Care and Emergency Medicine]

The task of physicians is to maintain life, to protect and re-establish health as well as to alleviate suffering and to accompany the dying until death, under consideration of the self-determination rights of patients. Increasingly more and differentiated options for this are becoming available in intensive care medicine. Within the framework of professional responsibility physicians must decide which of the available treatment options are indicated. This process of decision-making is determined by answering the following question: when and under which circumstances is induction or continuation of intensive care treatment justified? In addition to the indications, the advance directive of the patient is the deciding factor. Medical indications represent a scientifically based estimation that a therapeutic measure is suitable in order to achieve a defined therapy target with a given probability. The ascertainment of the patient directive is achieved in a graded process depending on the state of consciousness of the patient. The present article offers orientation assistance to physicians for these decisions which are an individual responsibility.

Liver transplantation for hepatocellular carcinoma--is there a risk of recurrence caused by intraoperative blood salvage autotransfusion?

BACKGROUND/AIMS

The use of intraoperative blood salvage autotransfusion (IBSA) during surgical approaches may contribute to tumour cell dissemination. Therefore, IBSA should be avoided in cases of malignancy. However, the risks of IBSA might be acceptable in liver transplantation (LT) for selected small hepatocellular carcinoma (HCC).

METHODS

In total, 136 recipients of LT with histologically proven HCC in the explanted liver were included in this analysis. With regard to tumour recurrence, 40 patients receiving IBSA despite HCC (IBSA group) were compared to 96 patients without IBSA (non-IBSA group).

RESULTS

Milan criteria as assessed in the explanted liver were fulfilled in 24 of 40 IBSA patients and 58 of 96 non-IBSA patients (p = 0.85). Five of 40 patients in the IBSA group and 18 of 96 patients in the non-IBSA group experienced tumour recurrence (p = 0.29). In spite the theoretical risk of tumour cell dissemination, the recurrence rate was not increased in the IBSA group.

CONCLUSION

Our results indicate that IBSA does not modify the risk of HCC recurrence. Therefore, in highly selected HCC patients undergoing LT, the use of IBSA appears to be justified.

Effects of restricted thoracic movement on the regional distribution of ventilation

BACKGROUND

Restricted thoracic movement is often encountered in patients, necessitating mechanical ventilation during surgery or intensive care treatment. High intraabdominal pressure, obesity or thorax rigidity and deformity reduce the chest distensibility and deteriorate the lung function. They render the selection of proper ventilator settings difficult and complicate the weaning process. Electrical impedance tomography (EIT) is currently being proposed as a bedside imaging method for monitoring regional lung ventilation. The objective of our study was to establish whether the effects of decreased chest compliance on regional lung ventilation can be determined by EIT.

METHODS

Ten healthy male volunteers were studied in our pilot study under three conditions: (1) unrestricted breathing and (2) restricted breathing by abdominal and (3) lower rib cage strapping. The subjects were followed during spontaneous tidal breathing in five postures (sitting, supine, prone, left and right side). EIT and spirometry data were acquired in each condition.

RESULTS

The distribution of ventilation in subjects with unrestricted breathing corresponded with the physiologically expected values. In the left and right lateral postures, abdominal and thoracic cage restrictions reduced the ventilation in the dependent lung areas; the non-dependent areas were unaffected. In the prone position, the ventilation of the dependent and non-dependent areas was reduced. The effects of strapping were least pronounced in the supine posture.

CONCLUSIONS

We conclude that EIT is able to measure changes in the regional distribution of ventilation induced by restricted chest movement and has the potential for optimising artificial ventilation in patients with limited chest compliance of different origins.

Prevention, diagnosis, therapy and follow-up care of sepsis: 1st revision of S-2k guidelines of the German Sepsis Society (Deutsche Sepsis-Gesellschaft e.V. (DSG)) and the German Interdisciplinary Association of Intensive Care and Emergency Medicine (Deutsche Interdisziplinäre Vereinigung für Intensiv- und Notfallmedizin (DIVI))

Practice guidelines are systematically developed statements and recommendations that assist the physicians and patients in making decisions about appropriate health care measures for specific clinical circumstances taking into account specific national health care structures. The 1^st revision of the S-2k guideline of the German Sepsis Society in collaboration with 17 German medical scientific societies and one self-help group provides state-of-the-art information (results of controlled clinical trials and expert knowledge) on the effective and appropriate medical care (prevention, diagnosis, therapy and follow-up care) of critically ill patients with severe sepsis or septic shock. The guideline had been developed according to the “German Instrument for Methodological Guideline Appraisal” of the Association of the Scientific Medical Societies (AWMF). In view of the inevitable advancements in scientific knowledge and technical expertise, revisions, updates and amendments must be periodically initiated. The guideline recommendations may not be applied under all circumstances. It rests with the clinician to decide whether a certain recommendation should be adopted or not, taking into consideration the unique set of clinical facts presented in connection with each individual patient as well as the available resources.

[Study protocol of the VISEP study. Response of the SepNet study group]

In the commentary by Zander et al. the authors appear concerned about the methods and results of our, at that time, unpublished sepsis trial evaluating hydroxyethyl starch (HES) and insulin therapy. Unfortunately, the authors' concerns are based on false assumptions about the design, conduct and modes of action of the compounds under investigation. For instance, in our study the HES solution was not used for maintenance of daily fluid requirements, so that the assumption of the authors that this colloid was used "exclusively" is wrong. Moreover, the manufacturer of Hemohes, the HES product we used, gives no cut-off value for creatinine, thus the assumption that this cut-off value was "doubled" in our study is also incorrect. Other claims by the authors such as that lactated solutions cause elevated lactate levels, iatrogenic hyperglycemia and increase O(2) consumption are unfounded. There is no randomized controlled trial supporting such a claim - this claim is neither consistent with our study data nor with any credible published sepsis guidelines or with routine practice worldwide. We fully support open scientific debate. Our study methods and results have now been published after a strict peer-reviewing process and this data is now open to critical and constructive reviewing. However, in our opinion this premature action based on wrong assumptions and containing comments by representatives of pharmaceutical companies does not contribute to a serious, unbiased scientific discourse.

Performance of electrical impedance tomography in detecting regional tidal volumes during one-lung ventilation

BACKGROUND

Electrical impedance tomography (EIT) is becoming a new medical imaging modality for continuous monitoring of regional lung function in the intensive care unit or operating room. The aim of our study was to evaluate the performance of EIT in detecting regional tidal volumes in patients during volume-controlled mechanical ventilation of one or both lungs.

METHODS

Ten adult patients undergoing elective thoracic surgery were included. EIT measurements were performed with the Goe-MF II EIT system. Data were collected before surgery during ventilation of both, the right and left lungs. Tidal volumes of 800 and 400 ml were applied during bilateral and unilateral ventilation, respectively.

RESULTS

Ventilation-related impedance changes determined in the whole chest cross-section during the right and left lung ventilation did not significantly differ from each other and were equal to 47.6+/-5.6% and 48.5+/-7.8% (mean+/-SD) of the value determined during bilateral ventilation. During unilateral ventilation, EIT clearly separated the ventilated and non-ventilated lung regions; nevertheless, ventilation-related impedance changes were also detected at the non-ventilated sides in areas corresponding to 3.4+/-4.1% and 12.4+/-6.9% of the scan halves during ventilation of the left and right lung, respectively. Changes in global tidal volumes were adequately detected by EIT during both bilateral and unilateral lung ventilation.

CONCLUSION

Although good separation of the ventilated and non-ventilated sides of the chest was possible, the data indicate that reliable quantification of regional tidal volumes during asymmetric or inhomogeneous distribution patterns requires regions-of-interest analysis.

M-Entropy guidance vs standard practice during propofol-remifentanil anaesthesia: a randomised controlled trial

Seventy-two patients undergoing routine surgical procedures under propofol-remifentanil anaesthesia were randomly assigned to receive either standard clinical practice (n = 35) or standard practice plus monitoring of depth of anaesthesia with M-Entropy (n = 37). Patients in the standard practice group received more propofol than the entropy group (mean (SD) 95 (14) vs 81 (22) microg.kg(-1).min(-1), respectively; p < 0.01), and less remifentanil (0.39 (0.08) vs 0.46 (0.08) microg.kg(-1).min(-1), respectively; p < 0.001). Loss of consciousness was best predicted by BIS (prediction probability (P(K)) 0.96) and response entropy (P(K) 0.93), whereas emergence was best predicted by response entropy (P(K) 0.94). The frequency of unwanted patient responses was higher in the standard practice group than in the entropy group (47 vs 27 total events, respectively; p < 0.01). Both regimens resulted in fast recovery with no clinical advantage for either one. There were no significant differences in haemodynamic parameters, postoperative nausea and vomiting or satisfaction with the procedure.

Reproducibility of regional lung ventilation distribution determined by electrical impedance tomography during mechanical ventilation

Electrical impedance tomography (EIT) has the potential to become a new tool for bedside monitoring of regional lung ventilation. The aim of our study was to assess the reproducibility of regional lung ventilation distribution determined by EIT during mechanical ventilation under identical ventilator settings. The experiments were performed on 10 anaesthetized supine pigs ventilated in a volume-controlled mode. EIT measurements were performed with the Goe-MF II device (Viasys Healthcare, Höchberg, Germany) during repeated changes in positive end-expiratory pressure (PEEP) from 0 to 10 cm H2O. Regional lung ventilation was determined in the right and left hemithorax as well as in 64 regions of interest evenly distributed over each chest side in the ventrodorsal direction. Ventilation distributions in both lungs were visualized as ventrodorsal ventilation profiles and shifts in ventilation distribution quantified in terms of centres of ventilation in relation to the chest diameter. The proportion of the right lung on total ventilation in the chest cross-section was 0.54+/-0.04 and remained unaffected by repetitive PEEP changes. Initial PEEP increase resulted in a redistribution of ventilation towards dorsal lung regions with a shift of the centre of ventilation from 45+/-3% to 49+/-3% of the chest diameter in the right and from 47+/-2% to 50+/-2% in the left hemithorax. Excellent reproducibility of the results in the individual regions of interest with almost identical patterns of ventilation distribution was found during repeated PEEP changes.

[Diagnosis and therapy of sepsis]

A recent survey conducted by the publicly funded Competence Network Sepsis (Sep- Net) reveals that severe sepsis and/or septic shock occurs in 75,000 inhabitants (110 out of 100,000) and sepsis in 79,000 inhabitants (116 out of 100,000) in Germany annually. This illness is responsible for approx. 60,000 deaths and ranges as the third most frequent cause of death after acute myocardial infarction. Direct costs for the intensive care of patients with severe sepsis alone amount to approx. 1.77 billion euros, which means that about 30% of the budget in intensive care is used to treat severe sepsis. However, until now German guidelines for the diagnosis and therapy of severe sepsis did not exist. Therefore, the German Sepsis Society initiated the development of guidelines which are based on international recommendations by the International Sepsis Forum (ISF) and the Surviving Sepsis Campaign (SSC) and take into account the structure and organisation of the German health care system. Priority was given to the following guideline topics: a) diagnosis, b) prevention, c) causative therapy, d) supportive therapy, e) adjunctive therapy. The guidelines development process was carefully planned and strictly adhered to according to the requirements of the Working Group of Scientific Medical Societies (AWMF).

[Diagnosis and therapy of sepsis. Guidelines of the German Sepsis Society Inc. and the German Interdisciplinary Society for Intensive and Emergency Medicine]

A recent survey conducted by the publicly funded Competence Network Sepsis (SepNet) reveals that severe sepsis and/or septic shock occurs in 75,000 inhabitants (110 out of 100,000) and sepsis in 79,000 inhabitants (116 out of 100,000) in Germany annually. This illness is responsible for approximately 60,000 deaths and ranges as the third most frequent cause of death after acute myocardial infarction. Direct costs for the intensive care of patients with severe sepsis alone amount to approximately 1.77 billion euros, which means that about 30% of the budget in intensive care is used to treat severe sepsis. However, until now German guidelines for the diagnosis and therapy of severe sepsis did not exist. Therefore, the German Sepsis Society initiated the development of guidelines which are based on international recommendations by the International Sepsis Forum (ISF) and the Surviving Sepsis Campaign (SSC) and take into account the structure and organization of the German health care system. Priority was given to the following guideline topics: a) diagnosis, b) prevention, c) causative therapy, d) supportive therapy, e) adjunctive therapy. The guidelines development process was carefully planned and strictly adhered to the requirements of the Working Group of Scientific Medical Societies (AWMF).

[Diagnosis and therapy of sepsis: guidelines of the German Sepsis Society Inc. and the German Interdisciplinary Society for Intensive and Emergency Medicine]

A recent survey conducted by the publicly funded Competence Network Sepsis (SepNet) reveals that severe sepsis and/or septic shock occurs in 75,000 inhabitants (110 out of 100,000) and sepsis in 79,000 inhabitants (116 out of 100,000) in Germany annually. This illness is responsible for approximately 60,000 deaths and ranges as the third most frequent cause of death after acute myocardial infarction. Direct costs for the intensive care of patients with severe sepsis alone amount to approximately 1.77 billion euros, which means that about 30% of the budget in intensive care is used to treat severe sepsis. However, until now German guidelines for the diagnosis and therapy of severe sepsis did not exist. Therefore, the German Sepsis Society initiated the development of guidelines which are based on international recommendations by the International Sepsis Forum (ISF) and the Surviving Sepsis Campaign (SSC) and take into account the structure and organization of the German health care system. Priority was given to the following guideline topics: a) diagnosis, b) prevention, c) causative therapy, d) supportive therapy, e) adjunctive therapy. The guidelines development process was carefully planned and strictly adhered to the requirements of the Working Group of Scientific Medical Societies (AWMF).

Cardiac function and haemodynamics during transition to high-frequency oscillatory ventilation

BACKGROUND AND OBJECTIVE

This prospective observational study analyses cardiovascular changes in adult patients with acute respiratory distress syndrome (ARDS) during transition from pressure-controlled ventilation to high-frequency oscillatory ventilation (HFOV), using transoesophageal echocardiography (TOE) and invasive haemodynamic monitoring.

METHODS

Nine patients (median age 65 years; range 42-70) with ARDS were studied. HFOV was started and maintained with an adjusted mean airway pressure of 5 cmH2O above the last measured mean airway pressure during pressure-controlled ventilation. Haemodynamic and TOE measurements were performed in end-expiration during baseline pressure-controlled ventilation, and again 5 and 30 min after the start of during uninterrupted HFOV.

RESULTS

Right atrial pressure increased immediately (P = 0.004). After 30 min, pulmonary arterial occlusion pressure increased (P = 0.008), cardiac index decreased (P = 0.01), stroke volume index decreased (P = 0.02) and both left ventricular end-diastolic and end-systolic area indices decreased (P = 0.02). Fractional area change, left ventricular end-systolic wall stress, heart rate, mean arterial pressure and mean pulmonary artery pressure remained unchanged.

CONCLUSIONS

Transition to HFOV at a mean airway pressure of 5 cmH2O above that during pressure-controlled ventilation induced significant, but clinically minor, haemodynamic effects, which are most probably due to airway pressure-related preload reduction.