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B Eberle

Publications and source records attributed to B Eberle.

At least 37 records · Page 2Linked to original sources
PubMed2001

Volumetry of ventilated airspaces by 3He MRI: preliminary results.

RATIONALE AND OBJECTIVES: To develop a validated post-processing routine for volumetry of the ventilated airspaces by 3He MRI. METHODS: 3Helium MRI and pulmonary function tests were performed in seven healthy volunteers. After segmentation of ventilated airspaces, their volumes were calculated. Functional residual capacity (FRC) was used as a reference. For comparison of absolute volumes, correction factors were evaluated. RESULTS: Mean lung volume (+/- standard deviation) calculated from 3He MRI was 4,082 +/- 908 mL and mean FRC was 3,696 +/- 1166 mL, with a mean difference of 386 mL (r = 0.88). After correction for the relative pulmonary air content (factor 0.82), posture (0.72), and the individual tidal volume, 3He MRI volume was 3,348 +/- 744 mL and mean FRC was 3,422 +/- 817 mL, with the mean difference down to -74 mL (r = 0.9). Comparison on an individual basis confirmed an improvement in the estimation of absolute lung volume. CONCLUSIONS: Volumetry of ventilated lung from 3He MRI shows high correlation and good agreement with the results of pulmonary function tests.

Adult↗
PubMed2000

(3)He MRI in healthy volunteers: preliminary correlation with smoking history and lung volumes.

MRI with hyperpolarized helium-3 ((3)He) provides high-resolution imaging of ventilated airspaces. The first aim of this (3)He-study was to compare observations of localized signal defects in healthy smokers and non-smokers. A second aim was to describe relationships between parameters of lung function, volume of inspired (3)He and signal-to-noise ratio. With Ethics Committee approval and informed consent, 12 healthy volunteers (seven smokers and five non-smokers) were studied. Imaging was performed in a 1.5 T scanner using a two-dimensional FLASH sequence at 30V transmitter amplitude (TR/TE/alpha = 11 ms/4.2 ms/<10 degrees ). Known amounts of (3)He were inhaled from a microprocessor-controlled delivery device and imaged during single breath-holds. Images were evaluated visually, and scored using a prospectively defined 'defect-index'. Signal-to-noise ratio of the images were correlated with localization, (3)He volumes and static lung volumes. Due to poor image quality studies of two smokers were not eligible for the evaluation. Smokers differed from non-smokers in total number and size of defects: the 'defect-index' of smokers ranged between 0.8 and 6.0 (median = 1.1), that of non-smokers between 0.1 and 0.8 (median = 0.4). Intraindividually, an anteroposterior gradient of signal-to-noise ratio was apparent. Signal-to-noise ratio correlated with the estimated amount of hyperpolarization administered (r = 0. 77), but not with static lung volumes. We conclude that (3)He MRI is a sensitive measure to detect regional abnormalities in the distribution of ventilation in clinically healthy persons with normal pulmonary function tests.

Adult↗
PubMed2000

Flip angle considerations in (3)helium-MRI.

3Helium-MRI ((3)He-MRI) can be used for analysis of lung function, e. g. dynamic imaging of ventilation and gas diffusion within the lung, assessment of intrapulmonary oxygen concentrations and their time course. During imaging, the irreversible signal loss due to depolarizing radio frequency excitations can be described using the flip angle (FA) alpha. This parameter has to be quantified in order to account for it during quantitative assessment of the (3)helium signal intensity and its temporal development. This technical report reviews two different methods to determine alpha. Limitations and possible error sources of each method are discussed.

Computer Simulation↗
PubMed2000

(3)he-MRI-based measurements of intrapulmonary p(O2) and its time course during apnea in healthy volunteers: first results, reproducibility, and technical limitations.

We applied a recently developed method of following the time course of the intrapulmonary oxygen partial pressure p(O2)(t) during apnea by (3)He MRI to healthy volunteers. Using two imaging series with different interscan times during two breathholds (double acquisition technique), relaxation of (3)He due to paramagnetic oxygen and depolarization by RF pulses were discriminated. In all four subjects, the temporal evolution of p(O2) was found to be linear, and was described by an initial partial pressure p(0) and a decrease rate R. Also, regional differences of both p(0) and R were observed. A correlation between p(0) and R was apparent. Finally, we discuss limitations of the double acquisition approach.

Adult↗
PubMed2000

[Ultrafast MRI of lung ventilation using hyperpolarized helium-3].

OBJECTIVE: Assessment of the temporal and spatial dynamics of hyperpolarized Helium-3 (3He) distribution in the lung with ultrafast gradient-echo magnetic-resonance imaging. MATERIAL AND METHODS: Coronal images of the lung were acquired using ultrafast gradient-echo pulse sequences with TR/TE = 3.3 ms/1.3 ms (slice thickness, 40 mm) and TR/TE = 2.0 ms/0.7 ms (without slice selection). A series of 80 or 160 projection images was obtained with 210 ms or 130 ms temporal resolution, respectively. Imaging was performed during several respiratory cycles after application of a single bolus of 300 mL hyperpolarized 3He. Measurements were performed in six healthy volunteers (spontaneous breathing). RESULTS: Different phases of in- and expiration could be visualized. During the course of consecutive respiratory cycles the 3He signal decreased due to dilution of 3He in residual alveolar gas and by inspired air, relaxation due to oxygen and the RF pulses, and due to Helium-3 washout. The signal of a single bolus of 3He was detected in the lung for up to four respiratory cycles. Anatomical structures were better visualized on slice selective images than on images without slice selection. CONCLUSION: Distribution of inspired 3He within the tracheobronchial tree and alveolar space and its washout can be visualized by ultrafast imaging of a single bolus of hyperpolarized 3He gas. This method may allow for regional analysis of lung function with temporal and spatial resolution superior to conventional methods.

Helium↗
PubMed2000

[19F-MRT of pulmonary ventilation in the breath-hold technic using SF6 gas].

OBJECTIVE: Development of a method to analyze lung ventilation by 19F-magnetic resonance imaging (MRI) of inspired SF6 gas during breath hold. MATERIAL AND METHODS: Measurements were performed with a Siemens Magnetom Vision 1.5 T scanner using the conventional gradient overdrive. Coronal images of the lung were acquired using ultrafast gradient-echo pulse sequences with TR/TE/alpha = 1.4 ms/0.48 ms/40 degrees without slice selection. With NEX = 200 averages and MA = 32 x 64 raw data matrix, the acquisition time was 9 s/image. Higher spatial resolution of 4.7 x 6.3 x 15 mm3 was obtained with a three-dimensional pulse sequence (TR/TE/alpha = 1.6 ms/0.48 ms/65 degrees, NEX = 20) running for 49 s. Measurements wer performed in three anesthetized and ventilated pigs (18 kg). RESULTS: A nearly linear relation between SF6 concentration and 19F signal intensity was observed. The signal-to-noise ratio in images obtained without slice selection was 30.9, with slice selection it was 14.9. No differences between SF6 distribution to both lungs were observed in the animals. CONCLUSION: Breath-hold MRI of SF6 gas distribution in the lung was demonstrated for the first time. The low spin-density was compensated for by highly repetitive signal averaging. Breath-hold 19F-MR imaging of ventilated airspaces to assess SF6 distribution in the human lung appears to be an interesting new method, which can be implemented with little technical efforts, and does not rely on radioactive isotopes.

Animals↗
PubMed2000

The carotid pulse check revisited: what if there is no pulse?

This study was undertaken to evaluate the diagnostic accuracy and time required by first responders to assess the carotid pulse in potentially pulseless patients. We conducted a prospective, randomized study of first responders (n = 206; four different training levels) and were blinded as to the patients' conditions in the cardiac operating rooms of a university hospital. Sixteen patients underwent coronary artery bypass surgery on nonpulsatile cardiopulmonary bypasses. Carotid pulse check was performed either during pulsatile (spontaneous) or during nonpulsatile (extracorporeal) circulation. Patients' hemodynamic status at the time of assessment, diagnostic accuracy of the first responders, and the time required to diagnose carotid pulsatility or pulselessness were documented. Within 10 secs, only 16.5% of the participants (34 of 206) were able to reach any decision about their patients' pulse status. Assessments that were both rapid and correct (15%, i.e., 31 of 206) occurred almost exclusively in pulsatile patients. Advanced training level shortened the delay to decision and improved its accuracy. However, merely 2% of the participants (1 of 59) correctly recognized a truly pulseless patient within 10 secs. Recognition of pulselessness of the carotid artery by rescuers with basic cardiopulmonary resuscitation training is time-consuming and highly inaccurate. Although the carotid pulse check needs to be taught, its importance in the context of layperson basic life support should be de-emphasized.

Cardiopulmonary Resuscitation↗
PubMed1999

Quantification of regional intrapulmonary oxygen partial pressure evolution during apnea by (3)He MRI.

We present a new method to determine in vivo the temporal evolution of intrapulmonary oxygen concentrations by functional lung imaging with hyperpolarized (3)Helium ((3)He-->). Single-breath, single-bolus visualization of (3)He--> administered to the airspaces is used to analyze nuclear spin relaxation caused by the local oxygen partial pressure p(O(2))(t). We model the dynamics of hyperpolarization in the lung by rate equations. Based hereupon, a double acquisition technique is presented to separate depolarization by RF pulses and oxygen induced relaxation. It permits the determination of p(O(2)) with a high accuracy of up to 3% with simultaneous flip angle calibration using no additional input parameters. The time course of p(O(2)) during short periods of breathholding is found to be linear in a pig as well as in a human volunteer. We also measured the wall relaxation time in the lung and deduced a lower limit of 4.3 min.

Adult↗
PubMed1999

[Hemodynamic effects of a ventriculo-cisternal perfusion of bupivacaine].

OBJECTIVES: The cardiotoxic properties of bupivacain have been well documented under in-vitro, as well as under in-vivo conditions. A further mechanism of cardiovascular impairment by bupivacaine via the central nervous system gained investigational interest in animal studies. The aim of our study was to demonstrate the effect of a ventriculocisternal perfusion of bupivacain on systemic hemodynamic variables and their reversibility by wash-out with mock-CSF. METHODS: After obtaining animal investional committee consent, nine anaesthetized and relaxed pigs were prepared for a ventriculocisternal perfusion (VCP). Hemodynamic data were obtained by invasive blood pressure measurements in the high and low pressure system as well as cardiac output (thermodilution technique), intracranial pressure and electrocardiogram. Systemic vascular resistance and stroke volume were calculated using standard formulas. A second group of three animals were exposed to an intravenous infusion of the same dose of bupivacain over the same period of time to rule out direct cardiac effects. After instrumentation baseline data were obtained (K0 1) under VCP with mock-CSF for 30 minutes. The mock-CSF was replaced by 0.05% bupivacaine in mock-CSF and VCP was continued with 3 ml.h-1 for 20 minutes. After administration of 500 micrograms bupivacaine data were collected (BU). The bupivacaine solution was replaced by mock-CSF and after twenty minutes hemodynamic measurement were repeated (K02). RESULTS: The intravenous administration of 500 micrograms bupivacaine had no effect on all measured variables. VCP of the same dose resulted in significant increase in heart rate, systolic, diastolic and mean arterial blood pressures. Left and right heart filling pressures as well as systemic vascular resistance were not affected while the stroke volume decreased. After continuation of VCP with mock-CSF hemodynamic changes were reversed. DISCUSSION: Our results demonstrate that bupivacaine initiates an indirect cardiovascular stimulating effect of a VCP with 500 micrograms of bupivacaine via the central nervous system. The intravenous administration of the same dose had no effect. The centrally mediated cardiovascular effect of bupivacaine was reversed by wash-out with mock-CSF. The cardiovascular stimulation observed in this animal experiment may be of clinical relevance as a potential sign of toxic effects of bupivacaine on the CNS.

Anesthetics, Local↗
PubMed1999

[Intraoperative blood requirements and allogeneic blood transfusion in cardioanesthesia. Data analysis of 7729 patients in 12 cardiac surgical clinics].

UNLABELLED: Allogeneic blood requirements in cardiac surgery shows a wide variation even for comparable procedures. The aim of the present study was to compare the intraoperative allogeneic blood requirement in defined cardiac operations among 12 cardiac centers in Germany. METHOD: A data set with 25 variables concerning the intraoperative course in adult cardiac patients with myocardial revascularization, valve replacement (aortic or/and mitral valve) or combined procedures was distributed to the participating centers. The data of all patients between January 1th 1998 and June 30th 1998 were included. Besides demographic data, the intraoperative transfusion of allogeneic and autologous blood, fresh frozen plasma and the concomitant hematocrit values were registered. Data were analyzed for all centers and separated for each center. RESULTS: The data of 7,729 patients were analyzed. The intraoperative allogeneic blood requirement was 0.6 +/- 1.3 units for all patients. It varied among the centers from 0.25 +/- 0.6 units to 0.97 +/- 1.6 units (P < 0.05). The percentage of patients receiving allogeneic blood was 27% and differed among the centers from 17% to 35%. Female patients were transfused in 53% (36-39%) compared to male patients with 16% (9-20%) (P < 0.05). The rate of autologous blood predonation varied from 0.5% to 23%. Patients without autologous predonation were transfused in 28% compared to 4% in patients with predonation (P < 0.05). In patients with autologous predonation the intraoperative transfusion of allogeneic blood was significantly reduced (0.1 +/- 0.39 vs 0.6 +/- 1.4 units, P < 0.05). However, some centers with a high percentage of autologous predonation also demonstrated a high rate of perioperative allogeneic transfusion. CONCLUSION: The incidence of allogeneic blood transfusion in cardiac surgery depends on the institution and not on the surgical procedure. A common threshold value of hemoglobin for the transfusion of blood trigger even for comparable procedures could not be detected among the centers. Especially in female patients, there was a wide variation in allogeneic blood transfusion. Autologous blood predonation reduces blood requirement significantly, however, it is practiced with variing intensity. The data set did not include information about transfusion regimen in the postoperative period, thus, these data do not allow to draw conclusions for the whole perioperative period.

Adult↗
PubMed1999

Successful treatment of a patient with ARDS after pneumonectomy using high-frequency oscillatory ventilation.

High frequency oscillatory ventilation (HFOV) was used in a patient who developed the acute respiratory distress syndrome 5 days following a right pneumonectomy for bronchogenic carcinoma. When conventional pressure-controlled ventilation failed to maintain adequate oxygenation, HFOV dramatically improved oxygenation within the first few hours of therapy. Pulmonary function and gas exchange recovered during a 10-day period of HFOV. No negative side effects were observed. Early use of HFOV may be a beneficial ventilation strategy for adults with acute pulmonary failure, even in the postoperative period after lung resection.

Airway Resistance↗
PubMed1999

Reduced inotropic support after aprotinin therapy during pediatric cardiac operations.

BACKGROUND: Several reports indicate that aprotinin treatment before and during cardiopulmonary bypass (CPB) might have a protective effect on the myocardium. We evaluated the hemodynamic effects of perioperative aprotinin treatment. METHODS: We conducted a randomized, double-blind, placebo-controlled trial in 34 infants (mean age, 2.5 years) who had cardiac operations. Half of the patients received high-dose aprotinin therapy. There were no significant differences between the aprotinin and placebo groups with respect to age, weight, sex, aortic cross-clamp time, and CPB time. The following data were recorded at arrival in the intensive care unit 6, 12, 24, and 48 hours after termination of CPB: heart rate, blood pressure, left atrial pressure, central-peripheral temperature difference, arterial-central venous oxygen saturation difference, urine output, serum creatinine, lactate and neutrophil elastase levels, the Doppler echocardiographic factors shortening fraction and preejection period/left-ventricular ejection time, and cumulative doses of catecholamines (epinephrine), enoximone, and furosemide. RESULTS: No hemodynamic variable showed any significant difference between aprotinin and placebo groups. Urine output, creatinine, lactate, and elastase levels, as well as the cumulative doses of furosemide and epinephrine were not significantly different. Twelve hours after CPB 10 patients in the placebo group and 4 in the aprotinin group had received enoximone (p<0.05). The placebo group had received significantly larger doses of enoximone than the aprotinin group at arrival in the intensive care unit (0.13+/-0.05 versus 0 mg/kg), 12 hours after CPB (0.58+/-0.14 versus 0.18+/-0.09 mg/kg), 24 hours after CPB (1.11+/-0.24 versus 0.42+/-0.16 mg/kg), and 48 hours after CPB (1.61+/-0.40 versus 0.86+/-0.28). At 6 hours the difference did not reach statistical significance. CONCLUSIONS: Clinical and hemodynamic status of the aprotinin-treated patients was similar to that of the placebo-treated patients in the first 48 hours after CPB. The placebo group, however, required significantly more inotropic support by enoximone than the aprotinin group to achieve this goal.

Adolescent↗
PubMed1999

Computed tomography-based tracheobronchial image reconstruction allows selection of the individually appropriate double-lumen tube size.

OBJECTIVES: To determine whether individualized selection of double-lumen tubes or alternatives based on three-dimensional reconstruction of the tracheobronchial image from routine preoperative computed tomography (CT) scans leads to clinically appropriate choices. DESIGN: Prospective observational study; comparison to historic controls. SETTING: Anesthesia and radiology facilities of a university medical center. PARTICIPANTS: Forty-nine patients undergoing thoracic surgery requiring one-lung ventilation. INTERVENTIONS: Three-dimensional image reconstruction of individual tracheobronchial anatomy was performed from routine preoperative spiral CT scans as well as from scans of five left-sided and four right-sided double-lumen tubes. Results of image-based tube size selection were compared with literature recommendations. Prospectively, individualized tube selection was performed by superimposition of printed transparencies of tubes over the tracheobronchial system and was validated using bronchoscopic and clinical criteria (n = 24). MEASUREMENTS AND MAIN RESULTS: Three-dimensional reconstruction visualized individual anatomy with good accuracy and resolution. Correlations between patient morphology and tracheobronchial dimensions were weak (height versus mainstem bronchial diameters: r < 0.50). In 11 of 48 patients (23%). CT-fitted double-lumen tube sizes would have differed from a conventional height-based and gender-based selection. Individual, prospective, CT-based double-lumen tube selection was associated with (1) good fit and positioning confirmed by fiberoptic bronchoscopy, (2) adequate bronchial cuff seal volumes, (3) complete lung separation, and (4) oxygenation and ventilation parameters during one-lung ventilation similar to those with conventional size selection. In one patient, three-dimensional CT study allowed noninvasive evaluation of a tracheal stenosis precluding double-lumen tube placement. CONCLUSION: Individualized selection of double-lumen tube size using CT-based reconstructions of tracheobronchial anatomy leads to clinically appropriate choices. Risks resulting from variations in tracheobronchial morphology are recognized in advance.

Adolescent↗
PubMed1999

[Multi-rotation CT during continuous ventilation: comparison of different density areas in healthy lungs and in the ARDS lavage model].

PURPOSE: In this animal study, density ranges for CT-based quantification of ventilated lung area were determined. Healthy lungs and ARDS lungs were compared during artificial respiration. MATERIAL AND METHODS: CT-scans were performed in 5 anesthetized pigs using a dynamic multiscan CT option on a predefined transverse slice (slice thickness 1 mm; effective temporal resolution, 250 ms). During continuous CT acquisition, airway pressure was increased or decreased in a stepwise manner. In all images, areas of defined HU ranges were determined planimetrically. The lower threshold was set to -910 HE in all images. The upper threshold was varied from -800 HE to -200 HE in steps of 100 HE. RESULTS: During inspiration in healthy lungs the HU-range of -910 to -700 HU showed the largest increase in area. During inspiration in ARDS lungs the HU range from -910 to -300 HU allowed the most sensitive assessment of area changes. These findings can be explained by recruitment of atelectases (HU-range > -300 HU) and their transition to a HU range from -700 to -300 HU. CONCLUSION: Dynamic multiscan CT acquisitions are a useful method to determine changes of ventilated lung area during a respiratory cycle. Different HU-ranges are required to access volume changes in healthy lungs and in ARDS lungs.

Animals↗
PubMed1999

Analysis of intrapulmonary O(2) concentration by MR imaging of inhaled hyperpolarized helium-3.

Inhalation of hyperpolarized (3)He allows magnetic resonance imaging (MRI) of ventilated airspaces. (3)He hyperpolarization decays more rapidly when interacting with paramagnetic O(2). We describe a method for in vivo determination of intrapulmonary O(2) concentrations ([O(2)]) based on MRI analysis of the fate of measured amounts of inhaled hyperpolarized (3)He in imaged regions of the lung. Anesthetized pigs underwent controlled normoventilation in a 1.5-T MRI unit. The inspired O(2) fraction was varied to achieve different end-tidal [O(2)] fractions (FET(O(2))). With the use of a specifically designed applicator, (3)He (100 ml, 35-45% polarized) was administered at a predefined time within single tidal volumes. During subsequent inspiratory apnea, serial two-dimensional images of airways and lungs were acquired. At least once in each animal studied, the radio-frequency excitation used for imaging was doubled at constant FET(O(2)). Signal intensity measurements in regions of interest of the animals' lungs (volume range, 54-294 cm(3)), taken at two different radio-frequency excitations, permitted calculation of [O(2)] in these regions of interest. The [O(2)] fractions in the regions of interest correlated closely with FET(O(2)) (R = 0.879; P < 0.0001). O(2)-sensitive (3)He-MRI may allow noninvasive study of regional distribution of ventilation and alveolar PO(2) in the lung.

Administration, Inhalation↗
PubMed1999

[Significance of the absorption of macromolecules for the immune response of an organism].

Numerous antigens are offered to the living organism by the daily food. With these investigations the influence of orally administered human gammaglobulin (HGG) on the immunity of sensitized animals after systemic immunization should be clarified. Experiments were performed in rabbits. Changes of the circulation were measured by bloodpressure registration and measurements of the organ flow. Simultaneous investigations of the antibody content, complement C3 and histamin were performed in the peripheral blood. In orally fed animals as well as in non fed controls an i.v. antigen challenge was performed. The level of circulating antibodies could be significantly decreased (60%) by the oral administration of HGG. In control animals the parenteral antigen challenge resulted in a mortality rate of 50%. In these animals the bloodpressure decreased significantly and long lasting, whereas antigen fed animals showed only a slight change in bloodpressure with normalization after a short period. During oral absorption of antigen complement factor C3 remained unchanged. In the first hour after the oral antigen administration a significant increase of histamin in the peripheral blood could be observed. Investigation with regard to the fate of the antibodies which were decreased by antigen feeding showed a storage in the layers of the gut which was depending on the dosage. It could be demonstrated that it is possible to influence the systemic immune response by the enteral application of macromolecules and this is also relevant for reactions of the circulation.

Animals↗