Sex differences in chest electrical impedance tomography findings.

Objective.Electrical impedance tomography (EIT) has been used to determine regional lung ventilation distribution in humans for decades, however, the effect of biological sex on the findings has hardly ever been examined. The aim of our study was to determine if the spatial distribution of ventilation assessed by EIT during quiet breathing was influenced by biological sex.Approach.219 adults with no known acute or chronic lung disease were examined in sitting position with the EIT electrodes placed around the lower chest (6th intercostal space). EIT data were recorded at 33 images/s during quiet breathing for 60 s. Regional tidal impedance variation was calculated in all EIT image pixels and the spatial distribution of the values was determined using the established EIT measures of centre of ventilation in ventrodorsal (CoVvd) and right-to-left direction (CoVrl), the dorsal and right fraction of ventilation, and ventilation defect score.Main results.After exclusion of one subject due to insufficient electrode contact, 218 data sets were analysed (120 men, 98 women) (age: 53 ± 18 vs 50 ± 16 yr (p= 0.2607), body mass index: 26.4 ± 4.0 vs 26.4 ± 6.6 kg m-2(p= 0.9158), mean ± SD). Highly significant differences in ventilation distribution were identified between men and women between the right and left chest sides (CoVrl: 47.0 ± 2.9 vs 48.8 ± 3.3% of chest diameter (p< 0.0001), right fraction of ventilation: 0.573 ± 0.067 vs 0.539 ± 0.071 (p= 0.0004)) and less significant in the ventrodorsal direction (CoVvd: 55.6 ± 4.2 vs 54.5 ± 3.6% of chest diameter (p= 0.0364), dorsal fraction of ventilation: 0.650 ± 0.121 vs 0.625 ± 0.104 (p= 0.1155)). Ventilation defect score higher than one was found in 42.5% of men but only in 16.6% of women.Significance.Biological sex needs to be considered when EIT findings acquired in upright subjects in a rather caudal examination plane are interpreted. Sex differences in chest anatomy and thoracoabdominal mechanics may explain the results.

[Ultrasound visualization of the guidewire and positioning of the central venous catheter : A prospective observational study]. / Sonographische Visualisierung des Führungsdrahtes und Positionierung des zentralen Venenkatheters : Eine prospektive Beobachtungsstudie.

BACKGROUND: After insertion of a central venous catheter (CVC) the catheter position must be controlled and a pneumothorax ruled out. OBJECTIVE: The aim was to examine whether the use of two standard acoustic windows known from emergency sonography examination techniques is feasible to 1) verify the correct intravenous localization and direction of the guidewire before final CVC insertion and 2) correctly predict the required CVC length for positioning of the catheter tip in the lower third of the superior vena cava. MATERIAL AND METHODS: This single center prospective observational study included adult patients (age ≥18 years) with an indication for CVC insertion after institutional ethics approval was obtained. Puncture sites were restricted to bilateral internal jugular and subclavian veins and except for duplicate examinations no further exclusion criteria were defined. After vessel puncture and insertion of the guidewire, the vena cava was displayed by an additional ultrasound examiner (sector scanner 1.5-3.6 MHz) using the transhepatic or subcostal acoustic window to localize the guidewire. For positioning of the CVC tip, the required catheter length in relation to the cavoatrial junction was measured using the guidewire marks during slow retraction and consecutive disappearance of the J­shaped guidewire tip from each acoustic window. From the resulting insertion length of the guidewire 4 cm was subtracted for the transhepatic and 2 cm for the subcostal window under the assumption that this length correlates to the distance from the cavoatrial junction. The CVC was finally inserted and a chest radiograph was performed for radiological verification of the CVC position. RESULTS: Of 100 included patients, 94 could finally be analyzed. The guidewire could be identified in the vena cava in 91 patients (97%) within a time period of 2.2 ± 1.9 min. In three patients, the wire could not be visualized, although two catheters had the correct position, while one catheter was incorrectly positioned in the opposite axillary vein. In the second study part, positioning of the CVC was evaluated in 44 of the 94 patients. In 5 of these 44 patients, the correct direction and disappearance of the guidewire from the acoustic window could also be reliably visualized; however, with the left subclavian vein as the puncture site, the respective catheters were up to 6 cm too short for correct positioning. Thus, these 5 patients were excluded from this analysis. In the remaining 39 patients, the position of the CVC tip was optimally located in the lower third of the superior vena cava according to the chest radiograph in 20 patients (51%), while it was relatively too high in 5 patients (13%) and too low (entrance of the right atrium) in 9 patients. In the other 5 patients, disappearance of the guidewire from the acoustic window was not definitely detectable. CONCLUSION: The presented intraprocedural ultrasound-based method using two standard acoustic windows is reliable for verification of the correct intravenous location and direction of the guidewire even before dilatation of the vessel puncture site for insertion of the catheter. Furthermore, the method allows the clinically acceptable measurement of the required length for catheter positioning. A chest radiograph can be waived provided the ultrasound examination (identification of the guidewire and exclusion of puncture-related complications such as pneumothorax) is unambiguous.

Optimized breath detection algorithm in electrical impedance tomography.

OBJECTIVE: This paper defines a method for optimizing the breath delineation algorithms used in electrical impedance tomography (EIT). In lung EIT the identification of the breath phases is central for generating tidal impedance variation images, subsequent data analysis and clinical evaluation. The optimisation of these algorithms is particularly important in neonatal care since the existing breath detectors developed for adults may give insufficient reliability in neonates due to their very irregular breathing pattern. APPROACH: Our approach is generic in the sense that it relies on the definition of a gold standard and the associated definition of detector sensitivity and specificity, an optimisation criterion and a set of detector parameters to be investigated. The gold standard has been defined by 11 clinicians with previous experience with EIT and the performance of our approach is described and validated using a neonatal EIT dataset acquired within the EU-funded CRADL project. MAIN RESULTS: Three different algorithms are proposed that improve the breath detector performance by adding conditions on (1) maximum tidal breath rate obtained from zero-crossings of the EIT breathing signal, (2) minimum tidal impedance amplitude and (3) minimum tidal breath rate obtained from time-frequency analysis. As a baseline a zero-crossing algorithm has been used with some default parameters based on the Swisstom EIT device. SIGNIFICANCE: Based on the gold standard, the most crucial parameters of the proposed algorithms are optimised by using a simple exhaustive search and a weighted metric defined in connection with the receiver operating characterics. This provides a practical way to achieve any desirable trade-off between the sensitivity and the specificity of the detectors.

Characteristic pattern of pleural effusion in electrical impedance tomography images of critically ill patients.

BACKGROUND: Electrical impedance tomography (EIT) is increasingly used for continuous monitoring of ventilation in intensive care patients. Clinical observations in patients with pleural effusion show an increase in out-of-phase impedance changes. We hypothesised that out-of-phase impedance changes are a typical EIT finding in patients with pleural effusion and could be useful in its detection. METHODS: We conducted a prospective observational study in intensive care unit patients with and without pleural effusion. In patients with pleural effusion, EIT data were recorded before, during, and after unilateral drainage of pleural effusion. In patients with no pleural effusion, EIT data were recorded without any intervention. EIT images were separated into four quadrants of equal size. We analysed the sum of out-of-phase impedance changes in the affected quadrant in patients with pleural effusion before, during, and after drainage and compared it with the sum of out-of-phase impedance changes in the dorsal quadrants of patients without pleural effusion. RESULTS: We included 20 patients with pleural effusion and 10 patients without pleural effusion. The median sum of out-of-phase impedance changes was 70 (interquartile range 49-119) arbitrary units (a.u.) in patients with pleural effusion before drainage, 25 (12-46) a.u. after drainage (P<0.0001) and 11 (6-17) a.u. in patients without pleural effusion (P<0.0001 vs pleural effusion before drainage). The area under the receiver operating characteristics curve was 0.96 (95% limits of agreement 0.91-1.01) between patients with pleural effusion before drainage and those without pleural effusion. CONCLUSIONS: In patients monitored with EIT, the presence of out-of-phase impedance changes is highly suspicious of pleural effusion and should trigger further examination.

Clinical performance of a novel textile interface for neonatal chest electrical impedance tomography.

OBJECTIVE: Critically ill neonates and infants might particularly benefit from continuous chest electrical impedance tomography (EIT) monitoring at the bedside. In this study a textile 32-electrode interface for neonatal EIT examination has been developed and tested to validate its clinical performance. The objectives were to assess ease of use in a clinical setting, stability of contact impedance at the electrode-skin interface and possible adverse effects. APPROACH: Thirty preterm infants (gestational age: 30.3 ± 3.9 week (mean ± SD), postnatal age: 13.8 ± 28.2 d, body weight at inclusion: 1727 ± 869 g) were included in this multicentre study. The electrode-skin contact impedances were measured continuously for up to 3 d and analysed during the initial 20-min phase after fastening the belt and during a 10 h measurement interval without any clinical interventions. The skin condition was assessed by attending clinicians. MAIN RESULTS: Our findings imply that the textile electrode interface is suitable for long-term neonatal chest EIT imaging. It does not cause any distress for the preterm infants or discomfort. Stable contact impedance of about 300 Ohm was observed immediately after fastening the electrode belt and during the subsequent 20 min period. A slight increase in contact impedance was observed over time. Tidal variation of contact impedance was less than 5 Ohm. SIGNIFICANCE: The availability of a textile 32-electrode belt for neonatal EIT imaging with simple, fast, accurate and reproducible placement on the chest strengthens the potential of EIT to be used for regional lung monitoring in critically ill neonates and infants.

[Bedside implantation of a new temporary vena cava inferior filter : German results from the European ANGEL registry]. / Bettseitige Implantation eines neuen passageren V.-cava-inferior-Filters : Deutsche Daten aus dem europäischen ANGEL-Register.

BACKGROUND: Pulmonary embolism (PE) is a frequently occurring complication in critically ill patients, and the simultaneous occurrence of PE and life-threatening bleeding is a therapeutic dilemma. Inferior vena cava filters (IVCF) may represent an important therapeutic alternative in these cases. The Angel® catheter (Bio2 Medical Inc., San Antonio, TX, USA) is a novel IVCF that provides temporary protection from PE and is implanted at bedside without fluoroscopy. MATERIAL AND METHODS: The European Angel® Catheter Registry is an observational, multicenter study. In our German substudy, we investigated patients from three German hospitals and four intensive care units, who underwent Angel® catheter implantation between February 2016 and December 2016. RESULTS: A total of 23 critically ill patients (68 ± 9 years, 43% male) were included. The main indication for implantation was a high risk for or an established PE, combined with contraindications for prophylactic or therapeutic anticoagulation due to either an increased risk of bleeding (81%) or active bleeding (13%). The Angel® catheter was successfully inserted in all patients at bedside. No PE occurred in patients with an indwelling Angel® catheter. Clots with a diameter larger the 20 mm, indicating clot migration, were detected in 5% of the patients by cavography before filter retrieval. Filter retrieval was uneventful in all of our cases, while filter dislocation occurred in 3% of the patients. CONCLUSION: The German data from the multicenter European Angel® Catheter Registry show that the Angel® catheter is a safe and effective approach for critically ill patients with a high risk for the development of PE or an established PE, when an anticoagulation therapy is contraindicated.

[Instantaneous wave-free ratio (iFR®) in patients with coronary artery disease]. / "Instantaneous wave-free ratio" (iFR®) bei Patienten mit koronarer Herzkrankheit.

Coronary angiography is considered as the gold standard in the morphological representation of coronary artery stenosis. Coronary angiography is often performed without preprocedural non-invasive proof of ischemia and the assessment of the severity of a coronary lesion by morphology is very subjective. Thus, invasive fractional flow reserve (FFR) measurement represents the current standard for estimation of the hemodynamic relevance of coronary artery stenosis and facilitates decision making for percutaneous coronary intervention (PCI) and stenting. The FFR-guided revascularization strategy has been classified as a class IA recommendation in the 2014 ESC/EACTS guidelines on myocardial revascularization. Both the DEFER and the FAME studies showed no treatment advantage of hemodynamically irrelevant stenosis. By use of FFR (and targeted interventions), clinical results could be improved as well as the procedure costs were reduced; however, the use in clinical practice is still limited due to the need of adenosine administration and a significant prolongation of the procedure. Instantaneous wave-free ratio (iFR®) is a new innovative approach for the determination of the hemodynamic relevance of coronary stenosis which can be obtained at rest without the use of vasodilators. Regarding periprocedural complications as well as prognosis, iFR® showed non-inferiority compared to FFR in the SWEDEHEART and DEFINE-FLAIR trials.

A prospective international observational prevalence study on prone positioning of ARDS patients: the APRONET (ARDS Prone Position Network) study.

INTRODUCTION: While prone positioning (PP) has been shown to improve patient survival in moderate to severe acute respiratory distress syndrome (ARDS) patients, the rate of application of PP in clinical practice still appears low. AIM: This study aimed to determine the prevalence of use of PP in ARDS patients (primary endpoint), the physiological effects of PP, and the reasons for not using it (secondary endpoints). METHODS: The APRONET study was a prospective international 1-day prevalence study performed four times in April, July, and October 2016 and January 2017. On each study day, investigators in each ICU had to screen every patient. For patients with ARDS, use of PP, gas exchange, ventilator settings and plateau pressure (Pplat) were recorded before and at the end of the PP session. Complications of PP and reasons for not using PP were also documented. Values are presented as median (1st-3rd quartiles). RESULTS: Over the study period, 6723 patients were screened in 141 ICUs from 20 countries (77% of the ICUs were European), of whom 735 had ARDS and were analyzed. Overall 101 ARDS patients had at least one session of PP (13.7%), with no differences among the 4 study days. The rate of PP use was 5.9% (11/187), 10.3% (41/399) and 32.9% (49/149) in mild, moderate and severe ARDS, respectively (P = 0.0001). The duration of the first PP session was 18 (16-23) hours. Measured with the patient in the supine position before and at the end of the first PP session, PaO2/FIO2 increased from 101 (76-136) to 171 (118-220) mmHg (P = 0.0001) driving pressure decreased from 14 [11-17] to 13 [10-16] cmH2O (P = 0.001), and Pplat decreased from 26 [23-29] to 25 [23-28] cmH2O (P = 0.04). The most prevalent reason for not using PP (64.3%) was that hypoxemia was not considered sufficiently severe. Complications were reported in 12 patients (11.9%) in whom PP was used (pressure sores in five, hypoxemia in two, endotracheal tube-related in two ocular in two, and a transient increase in intracranial pressure in one). CONCLUSIONS: In conclusion, this prospective international prevalence study found that PP was used in 32.9% of patients with severe ARDS, and was associated with low complication rates, significant increase in oxygenation and a significant decrease in driving pressure.

Diagnostic Performance of Contrast Enhanced Pulmonary Computed Tomography Angiography for the Detection of Angioinvasive Pulmonary Aspergillosis in Immunocompromised Patients.

Invasive pulmonary aspergillosis (IPA) is one of the major complications in immunocompromised patients. The mainstay of diagnostic imaging is non-enhanced chest-computed-tomography (CT), for which various non-specific signs for IPA have been described. However, contrast-enhanced CT pulmonary angiography (CTPA) has shown promising results, as the vessel occlusion sign (VOS) seems to be more sensitive and specific for IPA in hematologic patients. The aim of this study was to evaluate the diagnostic accuracy of CTPA in a larger cohort including non-hematologic immunocompromised patients. CTPA studies of 78 consecutive immunocompromised patients with proven/probable IPA were analyzed. 45 immunocompromised patients without IPA served as a control group. Diagnostic performance of CTPA-detected VOS and of radiological signs that do not require contrast-media were analyzed. Of 12 evaluable radiological signs, five were found to be significantly associated with IPA. The VOS showed the highest diagnostic performance with a sensitivity of 0.94, specificity of 0.71 and a diagnostic odds-ratio of 36.8. Regression analysis revealed the two strongest independent radiological predictors for IPA to be the VOS and the halo sign. The VOS is highly suggestive for IPA in immunocompromised patients in general. Thus, contrast-enhanced CTPA superior over non-contrast_enhanced chest-CT in patients with suspected IPA.

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]. / Gesundheitsbezogene Lebensqualität nach Beatmung auf der Intensivstation.

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 C­30 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.

[Computed tomography in patients with chronic stable angina : Fractional flow reserve measurement]. / Computertomographie bei Patienten mit stabiler Angina Pectoris : Messung der fraktionellen Flussreserve.

Coronary computed tomography angiography (cCTA) has been established for the non-invasive diagnosis of coronary artery disease (CAD). Previous studies demonstrated the high diagnostic accuracy of cCTA, particularly for ruling out CAD. As a known limitation of cCTA a large number of visually significant coronary stenoses are found to be hemodynamically not relevant by invasive fractional flow reserve (FFR). CT-based FFR (CT-FFR) builds on recent advances in computational fluid dynamics and image simulation techniques. Along with CT myocardial perfusion imaging, CT-FFR is a promising approach towards a more accurate estimation of the hemodynamic relevance of coronary artery stenoses. CT-FFR is derived from regular CT datasets without additional image acquisitions, contrast material, or medication. Two CT-FFR techniques can be differentiated. The initial method requires external use of supercomputers and has gained approval for clinical use in the USA. Furthermore, a prototype-software has been introduced which is less computationally demanding via integration of reduced-order models for on-site calculation of CT-FFR. The present article reviews these methods in the context of available study results and meta-analyses. Furthermore, limitations and future concepts of CT-FFR are discussed.

[Acute pulmonary embolism and contraindication of anticoagulation : Bedside implantation of a new temporary vena cava inferior filter]. / Akute Lungenembolie und Kontraindikation für eine Antikoagulation : Bettseitige Implantation eines neuen passageren V.-cava-inferior-Filters.

Pulmonary embolism (PE), mostly caused by deep vein thrombosis, is a life-threatening complication in critically ill patients in the intensive care unit. A potential strategy to prevent PE in patients with contraindication for anticoagulant therapy is the implantation of a vena cava filter (VCF), to provide fast and safe PE protection against ascending thrombi. We report the case of a 56-year-old woman with an intracranial hemorrhage, who developed a PE. Because of acute contraindications for anticoagulant therapy, bedside implantation of a new VCF was performed to overcome the period of absolute contraindications for anticoagulation. After explanation, several thrombi were found on the filter.

Comparison and outcome analysis of patients with apical and non-apical takotsubo cardiomyopathy.

BACKGROUND: Takotsubo cardiomyopathy (TTC) is a relevant differential diagnosis in patients presenting with signs of an acute coronary syndrome. Although recent literature has highlighted some salient features of this disorder, there has been little information elucidating the differences in clinical features, electrocardiographic findings, echocardiographic data and TTC-related complications associated with the different variants of TTC. METHODS AND RESULTS: Our institutional database constituted a collective of 114 patients diagnosed with TTC between 2003 and 2015 and these patients were subsequently divided into two groups based on the presence (n = 82, 72%) or absence (n = 32, 28%) of the apical form of TTC. The protocol for our proposed study was approved by the Ethics Committee of the University Medical Centre in Mannheim. It was noticed that the patients presenting with the apical form of TTC belonged to an older age group as compared to those presenting with the non-apical form (61.1 ± 8.9 years vs. 69.5 ± 11.2; P < 0.01). The QTc interval prolongation at index-event was observed to be quantifiably greater in the 'apical variant' patients group (484.8 ± 57 ms vs. 464 ± 34.1 ms; P = 0.06). With respect to cardiovascular risk factors, patients with arterial hypertension did have a higher predilection to present with the apical form (63.4% vs. 43.7%; P = 0.06), however, the impact of smoking was less pronounced in this patient group (24.4% vs. 50%, P = 0.01). Furthermore, our study highlighted a significant impact on ejection fraction (EF), with a compromised left ventricular function (36 ± 9% vs. 42.4 ± 9.7%, P < 0.01) and greater involvement of the right ventricle in the apical variant patients group (23% vs. 3%, P = 0.04). Patients with the apical form also showed a greater tendency to develop TTC-related complications such as cardiogenic shock and required longer monitoring and care in comparison. CONCLUSIONS: The apical and non-apical variants of TTC are manifestations of the same syndrome. They differ significantly, however, in their clinical presentation, related complications and prognosis.

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.

[Hyponatremia-induced life-threatening cerebral edema after ecstasy use]. / Hyponatriämieinduziertes lebensbedrohliches Hirnödem nach Ecstasykonsum.

Ecstasy, a psychoactive amphetamine derivative, is a popular party drug. We report the cases of 2 young adults who developed cerebral edema due to hyponatremia. One patient was released from the hospital without any sequelae, whereas the second patient died due to cerebral edema. Severe cases of symptomatic hyponatremia after ecstasy consumption are described in the literature with partially fatal clinical outcomes. Thus, physicians should be aware of early and consequent control of the sodium and choose an interdisciplinary treatment decision.