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Biomedical subjects

M Leuwer

Publications and source records attributed to M Leuwer.

At least 55 records · Page 3Linked to original sources
PubMed1999

Craniospinal axis irradiation in children. Treatment in supine position including field verification as a prerequisite for anesthesia without intubation.

PURPOSE: For craniospinal axis irradiation in young children sometimes anesthesia is required. In order to minimize risks from the anesthesist's point of view supine position would be preferable to standard prone position. In case of irradiation in supine position verification of the 3-field junction in the cervical region causes problems, because there is no direct visual control. For such situations the clinical application of a new technique is presented. PATIENTS AND METHODS: For treatment planning a modern 3D planning system was necessary. Patient's positioning was done by using a vacuum-form body immobilizer and an integrated head mask. Radiation fields were placed only by table movements being calculated by the planning system in relation to a reference point at the patient's surface. In addition to common verification films specially prepared small films were used for the 3-field junction in the cervical region. These films were placed close to the patient for the whole time of each radiation session being exposed by every radiation field. RESULTS: Two children (age 3 and 5 years, respectively) were irradiated as described. Twenty-eight of those specially prepared films were exposed. Two films (7%) had to be excluded because of inadequate exposure. An overlap of radiation fields was seen on 1 of the 26 remaining films (4%), whereas an unacceptable gap was not found. Acute skin reactions were comparable to those observed in patients being irradiated in standard prone position. CONCLUSION: The presented technique for craniospinal axis irradiation in supine position including field verification was not only precise and reproducable, but also comfortable and safe for the patient. We suggest it as a new option for craniospinal axis irradiation in children.

Anesthesia, General↗
PubMed1999

GM-CSF increases in vitro the respiratory burst of human neutrophils after liver transplantation.

OBJECTIVE: Superoxide production by polymorphonuclear neutrophils (PMNs) under cyclosporin A (CsA) therapy following kidney transplantation is impaired. We investigated if the respiratory burst of PMNs is similarly depressed in patients undergoing CsA treatment following orthotopic liver transplantation (OLTx). Additionally, the in vitro influence of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the superoxide anion production was examined during the respiratory burst. PATIENTS: 10 patients after OLTx and 10 healthy blood donors (control group). MEASUREMENTS AND RESULTS: PMNs were stimulated with bacteria (Escherichia coli) or a combination of tumour necrosis factor alpha (TNFalpha) and N-formyl-methionyl-leucyl-phenylalanine (FMLP). The respiratory burst was measured by oxidation of non-fluorescent dihydrorhodamine to the fluorescent rhodamine by means of flow cytometry. No differences in respiratory bursts from OLTx patients compared to those from healthy blood donors could be seen. Under TNFalpha/FMLP stimulation, the respiratory burst was significantly increased after in vitro incubation with GM-CSF (500 U ml(-1)) in patients following OLTx (from 58.2 to 74.5 %) as well as in the control group (from 47.4 to 61.9%). CONCLUSIONS: Our results demonstrate that superoxide production is not impaired under CsA treatment following OLTx. The respiratory burst of these patients' PMNs can even be augmented by GM-CSF in vitro.

Cyclosporine↗
PubMed1999

Septic shock after liver transplantation for Caroli's disease: clinical improvement after treatment with C1-esterase inhibitor.

The extent of complement and contact activation is related to outcome in sepsis. A low functional index of their main blocker C1-esterase inhibitor (C1-INH) is considered as a relative deficiency of C1-INH and might contribute to the development of fatal complications in the intensive care unit. The first results of therapeutic intervention with C1-INH concentrate in septic shock are promising. We report on our experience of C1-INH concentrate administration in a young woman with Caroli's disease as ultimate rescue therapy for septic shock with capillary leakage syndrome after combined liver and kidney transplantation. No focus of infection was detectable and thus surgical intervention was not indicated. Antibiotic therapy at that time included vancomycin, tobramycin, meropenem and fluconazol. Hemodynamic stabilization occurred within hours after administration of C1-INH concentrate. Simultaneously a reduction in vasopressor medication was possible and negative fluid balance was achieved.

Adult↗
PubMed1999

Neutrophil respiratory burst following liver transplantation: in vitro effects of granulocyte colony-stimulating factor.

Early postoperative infections and septic complications are predominant causes of morbidity and mortality in patients following orthotopic liver transplantation (OLTx). Prophylactic granulocyte colony-stimulating factor (G-CSF) administration after OLTx was found to decrease the number of sepsis episodes and sepsis-related mortality. Since polymorphonuclear neutrophils (PMNs) are one of the major determinants of antimicrobial defense, alteration of their functions may influence the development of sepsis in these patients. Therefore, we investigated in vitro whether or not priming with G-CSF affects the neutrophils' respiratory burst (RB) in immunosuppressed liver-transplanted patients. Venous blood was drawn from liver allograft recipients (n=12) between the 5th and 15th day postoperatively. Patients without clinical signs of infection or rejection were included in this study. Leukocytes were obtained as supernatant following sedimentation and incubated with 1000 IE ml-1 G-CSF. The RB was measured by the intracellular oxidation of non-fluorescent dihydrorhodamine to the fluorescent rhodamine by flow cytometry. The results were expressed as a percentage of increasing stimulation compared to the control responses, which are made up of the percentage of cells with RB reaction after stimulation with phorbol ester (PMA), bacteria (E. coli), or the combination of a cytokine (TNF-alpha) and a bacterial peptide (FMLP) in the absence of G-CSF. In vitro priming with G-CSF resulted in significantly increased activity of the RB after PMA (from 71.7% to 85.6%) and TNF-alpha/FMLP (from 58.4% to 72.7%) stimulation. These data demonstrate that G-CSF in vitro augments the RB of PMNs, thereby suggesting a possible therapeutic role for G-CSF as immunomodulating agent during bacterial and fungal infections following OLTx.

Flow Cytometry↗
PubMed1999

Xenon inhalation increases airway pressure in ventilated patients.

BACKGROUND: The inert gas xenon, known as an anaesthetic for nearly 50 years, is also used as a contrast agent during computerised tomography (CT)-scanning. As xenon has a higher density and viscosity than air, xenon inhalation may increase airway resistance. METHODS: In a retrospective study we investigated the effects of 33% xenon/67% oxygen on airway pressure and cardio-respiratory parameters in 37 long-term mechanically ventilated patients undergoing cerebral blood flow (rCBF) measurements by means of stable xenon-enhanced CT. RESULTS: Xenon administration caused a significant increase in peak airway pressure from 31.6+/-8.0 cm H2O to 42.7+/-16.9 cm H2O. This effect was reproducible, did not occur after reduction of inspiratory flow rate by 50% from 0.56+/-0.15 L x s(-1) to 0.28+/-0.08 L x s(-1), and vanished immediately after termination of xenon delivery. CONCLUSION: Due to the higher density and viscosity of this gas mixture, ventilation with xenon/oxygen produces a higher Reynolds' number than oxygen/air when given at the same flow rate. This means that during xenon ventilation the zone of transition from turbulent to laminar gas flow may be located more peripherally (in smaller airways) than during oxygen/air ventilation with a subsequent increase in airway resistance. Our results indicate that xenon inhalation may cause a clinically relevant increase of peak airway pressure in mechanically ventilated patients.

Administration, Inhalation↗
PubMed1999

Voltage-dependent block of normal and mutant muscle sodium channels by 4-Chloro-m-Cresol.

1 The effects of 4-Chloro-m-Cresol (4-CmC) were examined on heterologously expressed wild type (WT), Paramyotonia Congenita (R1448H) and Hyperkalemic Periodic Paralysis (M1360V) mutant alpha-subunits of human muscle sodium channels. 2 Block of rested sodium channels caused by 4-CmC was concentration-dependent with an ECR50 of 0.40 mM in WT, 0.45 mM in R1448H and 0.49 mM in M1360V. 3 Inactivation significantly promoted 4-CmC-induced sodium channel block in all clones indicated by 4-CmC-induced shifts of steady-state availability curves, reflecting a higher proportion of channel block at depolarized membrane potentials. Channel block was almost complete (>90%) at concentrations close to the ECR50 (0.5 mM) on application of an inactivating prepulse before the test pulse. 4 4-CmC accelerated the current decay following depolarization and prolonged recovery from inactivation in all clones. Of these, R1448H, the mutant which displayed severely impaired inactivation in the controls, responded to 4-CmC with the most pronounced acceleration of inactivation. Control experiments revealed enhanced recovery from inactivation in the mutants, which was restored to normal in 0.1 mM 4-CmC. 5 4-CmC induced no additional frequency-dependent block. 6 Our results clearly demonstrate that 4-CmC is as effective as lidocaine (Fan et al., 1996) in blocking muscle sodium channels. Low concentrations of the compound (</=ECR50) were able to restore pathologically accelerated recovery from inactivation and impaired inactivation in the mutants to the WT value.

Amino Acid Substitution↗
PubMed1999

Different effects of dopamine and dopexamine on the isolated perfused rat kidney.

We have investigated the effect of dopamine and dopexamine on the isolated perfused rat kidney. After an equilibration period of 20 min and two control periods of 10 min, dopexamine 1.0, 2.5 or 4.0 micrograms kg-1 min-1 or dopamine 2.0 micrograms kg-1 min-1 were perfused for a further 40 min in random order. Renal blood flow, urine volume, glomerular filtration rate, absolute sodium excretion and fractional sodium reabsorption of the isolated perfused kidney were measured every 10 min during the experiment. Dopamine increased significantly urine production from mean 61.54 (SEM 4.7) to 117.2 (9.7) microliters min-1 g-1 and absolute sodium excretion from 0.4 (0.1) to 1.2 (0.1) mumol min-1 g-1, and decreased significantly fractional sodium reabsorption from 97.3 (0.5) to 90.7 (0.7)%. Renal blood flow and glomerular filtration rate were not altered. In contrast, dopexamine had no effect on the isolated kidney. These data suggest that the diuretic and natriuretic effects of dopexamine in humans may not result from a direct action on the kidney.

Adrenergic beta-Agonists↗
PubMed1999

Increased reading speed for stories presented during general anesthesia.

BACKGROUND: In the absence of explicit memories such as the recall and recognition of intraoperative events, memory of auditory information played during general anesthesia has been demonstrated with several tests of implicit memory. In contrast to explicit memory, which requires conscious recollection, implicit memory does not require recollection of previous experiences and is evidenced by a priming effect on task performance. The authors evaluated the effect of a standardized anesthetic technique on implicit memory, first using a word stem completion task, and then a reading speed task in a subsequent study. METHODS: While undergoing lumbar disc surgery, 60 patients were exposed to auditory materials via headphones in two successive experiments. A balanced intravenous technique with propofol and alfentanil infusions and a nitrous oxide-oxygen mixture was used to maintain adequate anesthesia. In the first experiment, 30 patients were exposed randomly to one of the two lists of 34 repeated German nouns; in the second experiment, 30 patients were exposed to one of two tapes containing two short stories. Thirty control patients for each experiment heard the tapes without receiving anesthesia. All patients were tested for implicit memory 6-8 h later: A word stem completion task for the words and a reading speed task for the stories were used as measures of implicit memory. RESULTS: The control group completed the word stems significantly more often with the words that they had heard previously, but no such effect was found in the anesthetized group. However, both the control and patient groups showed a decreased reading time of about 40 ms per word for the previously presented stories compared with the new stories. The patients had no explicit memory of intraoperative events. CONCLUSIONS: Implicit memory was demonstrated after anesthesia by the reading speed task but not by the word stem completion task. Some methodologic aspects, such as using low frequency words or varying study and test modalities, may account for the negative results of the word stem completion task. Another explanation is that anesthesia with propofol, alfentanil, and nitrous oxide suppressed the word priming but not the reading speed measure of implicit memory. The reading speed paradigm seems to provide a stable and reliable measurement of implicit memory.

Adult↗
PubMed1999

Compositional, structural, and functional alterations in pulmonary surfactant in surgical patients after the early onset of systemic inflammatory response syndrome or sepsis.

OBJECTIVES: Sepsis is one of the most important predisposing factors for the development of the acute respiratory distress syndrome (ARDS). Alterations of pulmonary surfactant contribute in the pathogenesis of ARDS. However, little is known about surfactant in patients with less severe grades of lung injury related to sepsis or systemic inflammatory response syndrome (SIRS). Therefore, the purpose of this study was to characterize endogenous surfactant in surgical intensive care patients with sepsis or SIRS. DESIGN: Prospective, observational study. SETTING: University-affiliated, interdisciplinary intensive care unit. PATIENTS: Eleven patients after major surgery with SIRS or sepsis included within 12 hrs of onset and 11 controls without infection or lung disease. INTERVENTIONS: Operating room and standard intensive care unit management. MEASUREMENTS AND MAIN RESULTS: Four serial bronchoalveolar lavage samples (BAL) were recovered over 7 days from the patients and single BAL samples were obtained from controls. BAL cells, total protein, surfactant-associated protein A (SP-A), surfactant alveolar transition forms, and surface activity were analyzed. Two of 11 patients met criteria for acute lung injury and six of the 11 patients met ARDS consensus conference criteria but acute lung injury or ARDS was not persistent. The mean Pao2/F(IO)2 for the patients over 7 days was 253.2+/-15.1 (SEM) and Murray's lung injury score was 1.12+/-0.12, indicating mild-to-moderate lung injury. BAL neutrophil counts were increased (p< .01), and the ratio of poorly functioning light aggregate surfactant to superiorly functioning heavy aggregate surfactant was increased compared with controls (0.32+/-0.06 vs. 0.09+/-0.01, p < .05). SP-A was decreased (1.9+/-0.4 vs. 3.5+/-0.6 microg/mL of BAL, p< .05) and there were increases in the ratios of phospholipid to SP-A (p < .05), protein to SP.A (p < .01), and protein to phospholipid (p < .05). The surface tension-lowering ability of purified heavy aggregate surfactant was significantly impaired (15.6+/-1.6 vs. 2.8+/-0.6 milliNewtons/m, p< .05). CONCLUSIONS: These observations show that surgical patients with SIRS or sepsis who have mild-to-moderate lung injury develop surfactant dysfunction detectable within 7 days of onset. We propose, therefore, that therapeutic strategies to modulate these severe surfactant abnormalities should be considered, as these strategies may have the potential to reduce lung injury, which is associated with a high mortality in sepsis.

APACHE↗
PubMed1999

[Value of the laryngeal mask in emergency care--a survey of North German emergency physicians].

In clinical routine, the laryngeal mask airway (LMA) has proved an alternative to both endotracheal intubation and mask ventilation. In a survey among North German emergency physicians, aspects such as doctors' acquaintance with the LMA, the degree of ist distribution, its use and its potential benefits under non-hospital emergency conditions were evaluated. Seventeen per cent (n = 162) of physicians responded to the questionnaire, 75% of them (n = 122) anaesthetists. Although 73% (n = 119) were familiar with the use of the LMA from clinical experience, and again 73% would welcome having LMA use and application as part of the training of non-academic members of ambulance teams, only 24% (n = 37) of the responding doctors have an LMA on their emergency ambulances and merely twelve (7.4%) physicians reported actually using the LMA, one of them unsuccessfully. Sixty-three per cent considered the LMA the first-choice alternative in an unexpected "can't-ventilate-can't-intubate" situation. Use of the LMA should be extended in emergency medicine especially as its application is relatively easy to learn in clinical routine.

Attitude of Health Personnel↗
PubMed1998

Standard calculation of ethanol elimination rate is not sufficient to provide ethanol substitution therapy in the postoperative course of alcohol-dependent patients.

OBJECTIVE: Alcohol withdrawal syndrome (AWS) is a severe complication during postoperative treatment of alcohol-dependent patients. Besides the use of clomethiazole, clonidine, and benzodiazepines, there is another possible way to prevent AWS by deliberate administration of ethanol. The appropriate dosage of ethanol has not been known up to now and it could be defined according to the average ethanol elimination rate (EER) which, from forensic analysis, is known to be 15 mg/dl per h in a normal population. However, it is questionable whether these data are suitable for the calculation of the correct dosage in alcohol-dependent patients. DESIGN: Preliminary retrospective descriptive study. SETTING: Intensive care unit of a university teaching hospital. PATIENTS: 11 alcohol-dependent patients (9 males, 2 females, mean age 50.8 years, range 33 to 60 years). INTERVENTIONS: Ethanol substitution (ES) by parenteral application. MEASUREMENTS AND RESULTS: Ethanol kinetics were evaluated by repeated measurement of the blood ethanol concentration (BEC) over a period of at least 6 h parallel to the administration of ethanol. The average EER was found to be 28 mg/dl per h with a standard deviation of 11 mg/ dl per h. The minimum value was 18 mg/dl per h and the maximum 50 mg/dl per h. These EERs were significantly higher than the EERs known from forensic analysis. AWS was prevented in all 11 patients. CONCLUSIONS: Close control of BEC and precise adjustment of ethanol administration are necessary prerequisites for ES. The standard EER is not sufficient to define the appropriate ethanol dosage due to enormous variations in the ethanol metabolism of alcohol-dependent patients.

Adult↗
PubMed1998

Predictors of respiratory function deterioration after transfer of critically ill patients.

OBJECTIVES: Critically ill patients are often transferred due to the growing number of diagnostic procedures required to be performed outside the intensive care unit. These transfers have proved to be very critical. The aim of this study was to evaluate predictors for the deterioration of respiratory function in critically ill patients after transfer. DESIGN: Prospective, clinical, observational study. SETTING: 1800-bed university teaching hospital. SUBJECTS: 98 mechanically ventilated patients were investigated during transfer. MEASUREMENT AND MAIN RESULTS: Before transfer, all patients were classified according to the Acute Physiology and Chronic Health Evaluation (APACHE) II score and the Therapeutic Intervention Scoring System (TISS). Haemodynamics and arterial blood gases were measured at 11 different times. Arterial oxygen tension (PaO2), fractional inspired oxygen (FIO2), PaO2/FIO2 ratio, lowest PaO2/FIO2 ratio, minimal PaO2 and maximal FIO2, APACHE II score, TISS before transfer, age and duration of transfer were analysed as potential predictors for deterioration of respiratory function after transfer. Variables were analysed using Classification and Regression Trees and Clustering by Response. In 54 transports (55%) there was a decrease in the PaO2/FIO2 ratio, and a decrease of more than 20% from baseline was noted in 23 of the transferred patients (24%). Age > 43 years and FIO2 > 0.5 were identified as predictors for respiratory deterioration. CONCLUSIONS: Our predictors were able to indicate deterioration after transfer correctly in 20 of 22 patients (91%), combined with a false-positive rate in 17 of 49 (35%).

APACHE↗
PubMed1998

[Pulse oximetry and capnography in intensive care transportation: combined use reduces transportation risks].

OBJECTIVE: Due to the growing number of diagnostic and therapeutical procedures intensive-care patients must be transported intra- and interhospitally more often. These transports are among the most critical events during intensive-care therapy, with a high incidence of potentially life-threatening mishaps [23]. The aim of this study was to evaluate the possible benefit of the combined application of pulse oximetry and capnometry for patient safety during transport. METHODS: In a prospective clinical study 48 mechanically ventilated patients were allocated at random in 2 main study groups, 24 patients were investigated during interhospital transportation with an ambulance car, the other 24 patients during intrahospital transports. They were classified according to APACHE II and TISS. Blood pressure, heart rate and arterial blood gases were measured at eleven selected times. Twelve randomly chosen patients out of each main study group were monitored additionally with pulse oximetry and capnometry. The results were compared using the Mann-Whitney-U test. P < or = 0.05 was considered significant. RESULTS: Thirty-four patients had a TISS more than 40. The mean APACHE II-Score was 14 +/- 5. The overall incidence of potentially life-threatening mishaps was 9. Six out of these 9 occurred in the 24 patients with additional monitoring and were immediately detected by pulse oximetry or capnometry. CONCLUSIONS: The combination of pulse oximetry and capnometry offers the possibility to detect potentially life-threatening problems in ventilated patients during transport. This allows for early therapeutical consequences and may help to reduce the risk of transports.

APACHE↗