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To describe the principles and the first clinical application of a novel prototype automated weaning system called Evita Weaning System (EWS). EWS allows an automated control of all ventilator settings in pressure controlled and pressure support mode with the aim of decreasing the respiratory load of mechanical ventilation. Respiratory load takes inspired fraction of oxygen, positive end-expiratory pressure, pressure amplitude and spontaneous breathing activity into account. Spontaneous breathing activity is assessed by the number of controlled breaths needed to maintain a predefined respiratory rate. EWS was implemented as a knowledge- and model-based system that autonomously and remotely controlled a mechanical ventilator (Evita 4, Drager Medical, Lubeck, Germany). In a selected case study (n = 19 patients), ventilator settings chosen by the responsible physician were compared with the settings 10 min after the start of EWS and at the end of the study session. Neither unsafe ventilator settings nor failure of the system occurred. All patients were successfully transferred from controlled ventilation to assisted spontaneous breathing in a mean time of 37 ± 17 min (± SD). Early settings applied by the EWS did not significantly differ from the initial settings, except for the fraction of oxygen in inspired gas. During the later course, EWS significantly modified most of the ventilator settings and reduced the imposed respiratory load. A novel prototype automated weaning system was successfully developed. The first clinical application of EWS revealed that its operation was stable, safe ventilator settings were defined and the respiratory load of mechanical ventilation was decreased.

Mortality in intensive care unit (ICU) patients is affected by multiple variables. The possible impact of the mode of ventilation has not yet been clarified; therefore, a secondary analysis of the “epidemiology of sepsis in Germany” study was performed. The aims were (1) to describe the ventilation strategies currently applied in clinical practice, (2) to analyze the association of the different modes of ventilation with mortality and (3) to investigate whether the ratio between arterial partial pressure of oxygen and inspired fraction of oxygen (PF ratio) and/or other respiratory variables are associated with mortality in septic patients needing ventilatory support. A total of 454 ICUs in 310 randomly selected hospitals participated in this national prospective observational 1-day point prevalence of sepsis study including 415 patients with severe sepsis or septic shock according to the American College of Chest Physicians/Society of Critical Care Medicine criteria. Of the 415 patients, 331 required ventilatory support. Pressure controlled ventilation (PCV) was the most frequently used ventilatory mode (70.6 %) followed by assisted ventilation (AV 21.7 %) and volume controlled ventilation (VCV 7.7 %). Hospital mortality did not differ significantly among patients ventilated with PCV (57 %), VCV (71 %) or AV (51 %, p = 0.23). A PF ratio equal or less than 300 mmHg was found in 83.2 % of invasively ventilated patients (n = 316). In AV patients there was a clear trend to a higher PF ratio (204 ± 70 mmHg) than in controlled ventilated patients (PCV 179 ± 74 mmHg, VCV 175 ± 75 mmHg, p = 0.0551). Multiple regression analysis identified the tidal volume to pressure ratio (tidal volume divided by peak inspiratory airway pressure, odds ratio OR = 0.94, 95 % confidence interval 95% CI = 0.89–0.99), acute renal failure (OR = 2.15, 95% CI = 1.01–4.55) and acute physiology and chronic health evaluation (APACHE) II score (OR = 1.09, 95% CI = 1.03–1.15) but not the PF ratio (univariate analysis OR = 0.998, 95 % CI = 0.995–1.001) as independent risk factors for in-hospital mortality. This representative survey revealed that severe sepsis or septic shock was frequently associated with acute lung injury. Different ventilatory modes did not affect mortality. The tidal volume to inspiratory pressure ratio but not the PF ratio was independently associated with mortality.

Despite its ability to reduce overall ventilation time, protocol-guided weaning from mechanical ventilation is not routinely used in daily clinical practice. Clinical implementation of weaning protocols could be facilitated by integration of knowledge-based, closed-loop controlled protocols into respirators.To determine whether automated weaning decreases overall ventilation time compared with weaning based on a standardized written protocol in an unselected surgical patient population.In this prospective controlled trial patients ventilated for longer than 9 hours were randomly allocated to receive either weaning with automatic control of pressure support ventilation (automated-weaning group) or weaning based on a standardized written protocol (control group) using the same ventilation mode. The primary end point of the study was overall ventilation time.Overall ventilation time (median [25th and 75th percentile]) did not significantly differ between the automated-weaning (31 [19-101] h; n = 150) and control groups (39 [20-118] h; n = 150; P = 0.178). Patients who underwent cardiac surgery (n = 132) exhibited significantly shorter overall ventilation times in the automated-weaning (24 [18-57] h) than in the control group (35 [20-93] h; P = 0.035). The automated-weaning group exhibited shorter ventilation times until the first spontaneous breathing trial (1 [0-15] vs. 9 [1-51] h; P = 0.001) and a trend toward fewer tracheostomies (17 vs. 28; P = 0.075).Overall ventilation times did not significantly differ between weaning using automatic control of pressure support ventilation and weaning based on a standardized written protocol. Patients after cardiac surgery may benefit from automated weaning. Implementation of additional control variables besides the level of pressure support may further improve automated-weaning systems. Clinical trial registered with www.clinicaltrials.gov (NCT 00445289).

Pulmonary oxygen (O(2)) uptake during apnoea results in a fall in lung volume. Given that electrical impedance tomography (EIT) provides reliable data on regional lung volume changes we hypothesized that EIT could be used to measure regional O(2) uptake. A total of 12 lung healthy supine patients were studied. EIT measurements were performed during volume-controlled mechanical ventilation followed by apnoea with the endotracheal tube clamped at end-expiration. Lung function parameters were assessed by spirometry. A device for breath-by-breath monitoring metabolic gas exchange was used to measure global O(2) uptake. Relative impedance changes during ventilation and apnoea were related to the corresponding tidal volumes. Regional O(2) uptake was analysed as absolute values and as a ratio to regional ventilation in two regions of interest (ventral and dorsal). The global O(2) uptake measured by EIT was 208 ± 79 ml min(-1) corresponding to the values obtained by metabolic gas exchange (259 ± 73 ml min(-1); Spearman correlation coefficient: 0.81, p = 0.02). Regional O(2) uptake was significantly higher in the ventral lung region, while the regional O(2) uptake/ventilation ratio showed no significant difference between the regions. In conclusion, our pilot study indicates that EIT holds substantial potential to detect global and regional pulmonary O(2) uptake concordant with a linear lung volume decrease during apnoea.

Purpose: To compare unenhanced lung ventilation-weighted (VW) and perfusion-weighted (QW) imaging based on Fourier decomposition (FD) magnetic resonance (MR) imaging with the clinical reference standard single photon emission computed tomography (SPECT)/computed tomography (CT) in an animal experiment. Materials and Methods: The study was approved by the local animal care committee. Lung ventilation and perfusion was assessed in seven anesthetized pigs by using a 1.5-T MR imager and SPECT/CT. For time-resolved FD MR imaging, sets of lung images were acquired by using an untriggered two-dimensional balanced steady-state free precession sequence (repetition time, 1.9 msec; echo time, 0.8 msec; acquisition time per image, 118 msec; acquisition rate, 3.33 images per second; flip angle, 75 degrees; section thickness, 12 mm; matrix, 128 x 128). Breathing displacement was corrected with nonrigid image registration. Parenchymal signal intensity was analyzed pixelwise with FD to separate periodic changes of proton density induced by respiration and periodic changes of blood flow. Spectral lines representing respiratory and cardiac frequencies were integrated to calculate VW and QW images. Ventilation and perfusion SPECT was performed after inhalation of dispersed technetium 99m ((99m)Tc) and injection of (99m)Tc-labeled macroaggregated albumin. FD MR imaging and SPECT data were independently analyzed by two physicians in consensus. A regional statistical analysis of homogeneity and pathologic signal changes was performed. Results: Images acquired in healthy animals by using FD MR imaging and SPECT showed a homogeneous distribution of VW and QW imaging and pulmonary ventilation and perfusion, respectively. The gravitation-dependent signal distribution of ventilation and perfusion in all animals was similarly observed at FD MR imaging and SPECT. Incidental ventilation and perfusion defects were identically visualized by using both modalities. Conclusion: This animal experiment demonstrated qualitative agreement in the assessment of regional lung ventilation and perfusion between contrast media-free and radiation-free FD MR imaging and conventional SPECT/CT. (C) RSNA, 2011

Reliable assessment of regional lung ventilation and good reproducibility of electrical impedance tomography (EIT) data are the prerequisites for the future application of EIT in a clinical setting. The aims of our study were to determine (i) the reproducibility of repeated EIT measurements and (ii) the effect of the studied transverse chest plane on ventilation distribution in different postures.Ten healthy adult subjects were studied in three postures on two separate days. EIT and spirometric data were obtained during tidal breathing and slow vital capacity (VC) manoeuvres. EIT data were acquired in two chest planes at 13 scans/s. Reproducibility of EIT findings was assessed by Bland-Altman analysis and Pearson correlation in 16 regions of interest in each plane. Regional ventilation distribution during tidal breathing and deep expiration was determined as fractional ventilation in four quadrants of the studied chest cross-sections.Our study showed a good reproducibility of EIT measurements repeated after an average time interval of 8 days. Global tidal volumes and VCs determined by spirometry on separate days were not significantly different. Regional ventilation in chest quadrants assessed by EIT was also unaffected. Posture exerted a significant effect on ventilation distribution among the chest quadrants during spontaneous breathing and deep expiration in both planes. The spatial distribution patterns in the two planes were not identical.We conclude that regional EIT ventilation findings are reproducible and recommend that the EIT examination location on the chest is carefully chosen especially during repeated measurements and follow-up.

Training of medical personnel using simulation techniques is an acknowledged measure of process optimization and quality assurance in a clinical setting. In 2006, a simulator-based training of anaesthesiologists was introduced in the University Medical Centre of Schleswig-Holstein, Campus Kiel, Germany. The training was performed on a human patient simulator (Meti, Sarasota, USA) and the course was conducted by instructors and engineers from the Simulation Centre Mainz in an operation room equipped with common anaesthesia devices. Special lectures focused at crisis resource management and human errors were held in separate rooms. Parallel daily trainings of 6 physicians and 4 nurses were conducted during 9 days. The training was offered to the anaesthesia personnel of whole Schleswig-Holstein, Germany. A higher and more balanced overall performance of the participants was determined by the instructor teams in comparison to the training results in their own simulation centre. This improved performance was ascribed to the special circumstances of this training namely the familiar surroundings and team members.

To identify current clinical practice regarding nutrition and its association with morbidity and mortality in patients with severe sepsis or septic shock in Germany.Nationwide prospective, observational, cross-sectional, 1-day point-prevalence study.The study included 454 intensive care units from a representative sample of 310 hospitals stratified by size.Participants were 415 patients with severe sepsis or septic shock (according to criteria of the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference).None.Data were collected by on-site audits of trained external study physicians during randomly scheduled visits during 1 yr. Valid data on nutrition were available for 399 of 415 patients. The data showed that 20.1% of patients received exclusively enteral nutrition, 35.1% exclusively parenteral nutrition, and 34.6% mixed nutrition (parenteral and enteral); 10.3% were not fed at all. Patients with gastrointestinal/intra-abdominal infection, pancreatitis or neoplasm of the gastrointestinal tract, mechanical ventilation, or septic shock were less likely to receive exclusively enteral nutrition. Median Acute Physiology and Chronic Health Evaluation II and Sepsis-related Organ Failure Assessment scores were significantly different among the nutrition groups. Overall hospital mortality was 55.2%. Hospital mortality was significantly higher in patients receiving exclusively parenteral (62.3%) or mixed nutrition (57.1%) than in patients with exclusively enteral nutrition (38.9%) (p = .005). After adjustment for patient morbidity (Acute Physiology and Chronic Health Evaluation II score, presence of septic shock) and treatment factors (mechanical ventilation), multivariate analysis revealed that the presence of parenteral nutrition was significantly predictive of mortality (odds ratio, 2.09; 95% confidence interval, 1.29-3.37).Patients with severe sepsis or septic shock in German intensive care units received preferentially parenteral or mixed nutrition. The use of parenteral nutrition was associated with an increased risk of death.

In spite of decreasing incidence stress-related gastrointestinal bleeding is still an important problem in intensive care medicine. Especially patients with severe sepsis or septic shock are prone to develop lesions of the upper gastrointestinal tract with consecutive bleeding. In order to prevent gastrointestinal bleeding various pharmacological agents are used to either suppress gastric acid or neutralize its effect. The following article presents an update on important aspects of stress-related mucosal disease. It further reviews current literature to provide evidence-based recommendations for stress ulcer prophylaxis in septic patients.

In acute lung injury (ALI), the application of positive end-expiratory pressure (PEEP) is known to prevent the alveoli from cyclic collapse and reopening and to homogenize ventilation. The setting of adequate PEEP could be optimized by the knowledge of regional lung opening and closing pressures at the bedside. The aim of our study was to determine regional opening and closing pressures in ventilated patients by electrical impedance tomography (EIT).Eight patients with healthy lungs and 18 patients with ALI were studied. A low-flow inflation and deflation maneuver with constant gas flow was performed. Regional opening and closing pressures were calculated for every pixel of the EIT scan. These pressures were defined as those values of global airway pressure at which the lung areas opened up or started to close.Injured lungs exhibited significantly higher regional opening pressures compared with healthy lungs (P.05). In ALI, significantly higher opening pressures were found in the dependent lung regions. Regional closing pressures did not significantly differ between healthy and injured lungs.Regional lung opening and closing pressures can be assessed by EIT. This information may facilitate the setting of adequate PEEP levels in patients in future.

Introduction Interventional lung assist (ILA), based on the use of a pumpless extracorporeal membrane oxygenator, facilitates carbon dioxide (CO2) elimination in acute respiratory distress syndrome (ARDS). It is unclear whether an ILA system should be clamped during cardiopulmonary resuscitation (CPR) in patients with ARDS or not. The aim of our study was to test the effects of an ILA on haemodynamics and gas exchange during CPR on animals with ARDS and to establish whether the ILA should be kept open or clamped under these circumstances. Methods The study was designed to be prospective and experimental. The experiments were performed on 12 anaesthetised and mechanically ventilated pigs (weighing 41 to 58 kg). One femoral artery and one femoral vein were cannulated and connected to an ILA. ARDS was induced by repeated bronchoalveolar lavage. An indwelling pacemaker was used to initiate ventricular fibrillation and chest compressions were immediately started and continued for 30 minutes. In six animals, the ILA was kept open and in the other six it was clamped. Results Systolic and mean arterial pressures did not differ significantly between the groups. With the ILA open mean ± standard deviation systolic blood pressures were 89 ± 26 mmHg at 5 minutes, 71 ± 28 mmHg at 10 minutes, 63 ± 33 mmHg at 20 minutes and 83 ± 23 mmHg at 30 minutes. The clamped ILA system resulted in systolic pressures of 77 ± 30 mmHg, 90 ± 23 mmHg, 72 ± 11 mmHg and 72 ± 22 mmHg, respectively. In the group with the ILA system open, arterial partial pressure of CO2 was significantly lower after 10, 20 and 30 minutes of CPR and arterial partial pressure of oxygen was higher 20 minutes after the onset of CPR (191 ± 140 mmHg versus 57 ± 14 mmHg). End-tidal partial pressure of CO2 decreased from 46 ± 23 Torr (ILA open) and 37 ± 9 Torr (ILA clamped) before intervention to 8 ± 5 Torr and 8 ± 10 Torr, respectively, in both groups after 30 minutes of CPR. Conclusions Our results indicate that in an animal model of ARDS, blood pressures were not impaired by keeping the ILA system open during CPR compared with the immediate clamping of the ILA with the onset of CPR. The effect of ILA on gas exchange implied a beneficial effect.

Critical care 26(1), 23 (1922). doi:10.1186/s13054-022-03896-3, Published by BioMed Central, London

Introduction Current international sepsis guidelines recommend low-dose enteral nutrition (EN) for the first week. This contradicts other nutrition guidelines for heterogenous groups of ICU patients. Data on the optimal dose of EN in septic patients are lacking. Our aim was to evaluate the effect of energy and protein amount given by EN on clinical outcomes in a large cohort of critically ill septic patients.

Background Lung tissue of patients with acute respiratory distress syndrome (ARDS) is heterogeneously damaged and prone to develop atelectasis. During inflation, atelectatic regions may exhibit alveolar recruitment accompanied by prolonged filling with air in contrast to regions with already open alveoli with a fast increase in regional aeration. During deflation, derecruitment of injured regions is possible with ongoing loss in regional aeration. The aim of our study was to assess the dynamics of regional lung aeration in mechanically ventilated patients with ARDS and its dependency on positive end-expiratory pressure (PEEP) using electrical impedance tomography (EIT). Methods Twelve lung healthy and twenty ARDS patients were examined by EIT during sustained step increases in airway pressure from 0, 8 and 15 cm H2O to 35 cm H2O and during subsequent step decrease to the corresponding PEEP. Regional EIT waveforms in the ventral and dorsal lung regions were fitted to bi-exponential equations. Regional fast and slow respiratory time constants and the sizes of the fast and slow compartments were subsequently calculated. Results ARDS patients exhibited significantly lower fast and slow time constants than the lung healthy patients in ventral and dorsal regions. The time constants were significantly affected by PEEP and differed between the regions. The size of the fast compartment was significantly lower in ARDS patients than in patients with healthy lung under all studied conditions. Conclusion These results show that regional lung mechanics can be assessed by EIT. They reflect the lower respiratory system compliance of injured lungs and imply more pronounced regional recruitment and derecruitment in ARDS patients.

Introduction To accomplish early enteral feeding in the critically ill patient a new transnasal endoscopic approach to the placement of postpyloric feeding tubes by intensive care physicians was evaluated. Methods This was a prospective cohort study in 27 critically ill patients subjected to transnasal endoscopy and intubation of the pylorus. Attending intensive care physicians were trained in the handling of the new endoscope for transnasal gastroenteroscopy for two days. A jejunal feeding tube was advanced via the instrument channel and the correct position assessed by contrast radiography. The primary outcome measure was successful postpyloric placement of the tube. Secondary outcome measures were time needed for the placement, complications such as bleeding and formation of loops, and the score of the placement difficulty graded from 1 (easy) to 4 (difficult). Data are given as mean values and standard deviation. Results Out of 34 attempted jejunal tube placements, 28 tubes (82%) were placed correctly in the jejunum. The duration of the procedure was 28 ± 12 minutes. The difficulty of the tube placement was judged as follows: grade 1: 17 patients, grade 2: 8 patients, grade 3: 7 patients, grade 4: 2 patients. In three cases, the tube position was incorrect, and in another three cases, the procedure had to be aborted. In one patient bleeding occurred that required no further treatment. Conclusions Fast and reliable transnasal insertion of postpyloric feeding tubes can be accomplished by trained intensive care physicians at the bedside using the presented procedure. This new technique may facilitate early initiation of enteral feeding in intensive care patients.

Hintergrund: In Deutschland sind Unfälle die häufigste Todesursache in der Altersgruppe der 15 bis 40-Jährigen. Schwerstverletzte Patienten haben das Risiko eine akzidentelle Hypothermie im Rahmen der „Lethal triad“ zu entwickeln. Die akzidentelle Hypothermie ist ein fortdauernder Gegenstand der Diskussion im klinischen Verlauf einer Schwerstverletzung. Zielsetzung: Das Ziel dieser Arbeit sind die Erfassung und Beschreibung der akzidentellen Hypothermie des schwerstverletzten Patienten. Methoden: In einer retrospektiven Analyse werden dazu Patientendaten aus den Jahren 2002 bis 2012 aus dem Trauma Register der Deutschen Gesellschaft für Unfallchirurgie (DGU) ausgewertet. Die Daten werden durch den Standard-Dokumentationsbogen des TraumaRegister DGU® erhoben und beinhalten präklinische und klinische Parameter. Die Patienten sind anhand der Körpertemperatur in verschiedene Gruppen eingeteilt. Es werden die schwerstverletzen Patienten mit und ohne vorliegende akzidentelle Hypothermie verglichen. Eine univariate Analyse demonstriert die Ergebnisse als Mittelwert mit Standardabweichung. Kategorische und kontinuierliche Variablen werden mittles χ² Test, beziehungsweise mittels Student t Test und mittels Varianzanalyse zweier Gruppen analysiert. Das statistische Signifikanzniveau liegt bei p

Eine mögliche Komplikation der aortokoronaren Bypassoperation (ACB) ist der perioperative Myokardinfarkt (PMI). Ein wichtiges Diagnosekriterium des PMI ist der laborchemische Nachweis von Herzmuskelenzymen, speziell kardiales Troponin T, aus dem Blut der Patienten. Seit 2010 Markteinführung von neuen Immunoassays, das sogenannte hochsensitive Troponin T der fünften Generation (hsTnT). Dadurch noch sensitiverer und exakterer Nachweis von Troponin T möglich. Es gibt bislang keine Studien, welche die Kinetik des hsTnT nach ACB untersuchen. Fragestellung Ziel der Arbeit ist die Darstellung der Kinetik des hsTnT nach elektiver ACB im Vergleich zu Aortenklappenersatz-Operationen (AKE), jeweils On-Pump. Ergebnisse Deutliche Überschreitung der aktuell gültigen laborchemischen Definition eines PMI im Zusammenhang mit ACB (Myokardinfarkt Typ V) zu den Messzeitpunkten bis 24 Stunden postoperativ der ACB Gruppe Schlussfolgerung Eine >10fache Erhöhung der 99. Perzentile eines gesunden Vergleichskollektives als laborchemischer Cut-off-Wert zur Diagnose eines PMIs ist zu niedrig.