Wolfgang Lederer - Academia.edu (original) (raw)
Papers by Wolfgang Lederer
Notfall & Rettungsmedizin, 2001
Deut Med Wochenschr, 2006
Most epidemiological studies suffer from misclassification in the response and/or the covariates.... more Most epidemiological studies suffer from misclassification in the response and/or the covariates. Since ignoring misclassification induces bias on the parameter estimates, correction for such errors is important. For measurement error, the continuous analog to misclassification, a general approach for bias correction is the SIMEX (simulation extrapolation) originally suggested by . This approach has been recently extended to regression models with a possibly misclassified categorical response and/or the covariates by , and is called the MC-SIMEX approach. To assess the importance of a regressor not only its (corrected) estimate is needed, but also its standard error. For the original SIMEX approach. developed a method for estimating the asymptotic variance. Here we derive the asymptotic variance estimators for the MC-SIMEX approach, extending the methodology of . We also include the case where the misclassification probabilities are estimated by a validation study. An extensive simulation study shows the good performance of our approach. The approach is illustrated using an example in caries research including a logistic regression model, where the response and a binary covariate are possibly misclassified.
Der Anaesthesist
The number of diagnostic and surgical procedures being performed outside the core operating area ... more The number of diagnostic and surgical procedures being performed outside the core operating area is growing disproportionately. Due to the higher perioperative risk for such patients, anesthesia should only be provided by a very experienced anesthesiologist, even for supposedly small interventions. At these locations, timely and direct access to the anesthesia machine and/or the patient is often limited and if additional personnel or supplies are required, substantial time delays usually occur and should be allowed for. Standard operating procedures that are optimized to local requirements and providing a specially equipped anesthesia trolley for diagnostic and surgical procedures outside of the core operating area, may decrease the likelihood of complications induced by poorly equipped anesthesia workplaces. For electroconvulsive therapy (ECT), the standard drugs are methohexital in combination with short-acting opioids, such as remifentanil and succinylcholine. Significant variations in arterial blood pressure and heart rate are possible. Anesthesia induction in children with a known difficult airway or difficult intravascular access should initially be performed in a location with optimal infrastructure with subsequent transfer to the diagnostic or surgical suite outside the core operating area. Before entering the magnetic resonance imaging (MRI) suite, personal ferromagnetic items (e.g. pens, credit cards, stethoscopes, keys, telephones, USB sticks) should be removed to prevent injury and data loss; a MRI-compatible anesthesia machine and equipment is compulsory. Patients with cardiac pacemakers, cochlea implants, aneurysm or other clips, metallic-based tattoos or make-up are not normally compatible with MRI. General anesthesia should be preferred over conscious sedation for magnetic resonance imaging and ear protection is necessary for anesthetized patients. Gastroscopy in children should be performed under general anesthesia; and when concluding the procedure, air insufflated into the gastrointestinal tract should be suctioned in all patients. For angiography, maximum monitoring needs to be available to provide hemodynamically unstable patients with adequate anesthesia care; comprehensive radiation protection for patients and staff as well as temperature monitoring for prolonged diagnostic procedures is also necessary. Monitoring oxygen saturation and end-tidal carbon dioxide as well as employing visual and audible alarms is an essential requirement even during conscious sedation. In summary, the number of diagnostic and surgical procedures performed outside the core operating area should be reduced to a minimum and, whenever possible, diagnostic or surgical procedures should be performed within the core operating area.
Anesthesia and Analgesia, 2008
For the "Helfen Berü hrt" Study Team BACKGROUND: Many surgical interventions worldwide are perfor... more For the "Helfen Berü hrt" Study Team BACKGROUND: Many surgical interventions worldwide are performed in developing countries. To improve survival of acutely and critically ill patients in these countries, basic problems and demands of anesthesia care need to be identified. Using this survey, we evaluated the current status of anesthesia and its allied disciplines (intensive care medicine, emergency medicine, and pain therapy) in the Republic of Zambia. METHODS: Questionnaires were sent to 87 hospitals registered at the Zambian Ministry of Health as performing minor or major surgery. The questionnaire consisted of 111 questions grouped into five sections: general hospital information, anesthesia, intensive care, emergency medicine, and pain therapy. RESULTS: Sixty-eight questionnaires could be statistically evaluated (78%). The most common operations were obstetric/gynecological and abdominal surgical procedures. Dissociative ketamine anesthesia was the technique most often used for general anesthesia (50%). Endotracheal intubation was performed in 10% of patients undergoing general anesthesia. In most hospitals (78%), anesthesia was administered by nonphysicians. Only 5 of 68 hospitals (7%) reported having an intensive care unit, with 29 beds to serve the entire country. Anesthesiologists play almost no role in emergency medicine and pain therapy. CONCLUSIONS: Anesthesia in the Republic of Zambia is a highly under-developed and under-resourced medical specialty.
Notfall & Rettungsmedizin, 2002
ABSTRACT Grundpfeiler der Versorgung von blitzschlaginduziertem Atem- und Herzstillstand ist die ... more ABSTRACT Grundpfeiler der Versorgung von blitzschlaginduziertem Atem- und Herzstillstand ist die Basisreanimation durch Ersthelfer. Die Hauptaufmerksamkeit gilt der adäquaten Beatmung und Thoraxkompression. Herz-Lungen-Wiederbelebung kann auch nach verzögertem Beginn und sogar nach länger dauernden Reanimationsmaßnahmen erfolgreich sein. Wenn mehrere Personen gleichzeitig betroffen sind, müssen die Standardprinzipien der Triage modifiziert werden. Oberste Priorität erhalten bewusstlose Patienten ohne spontane Atmung und Kreislauf. Wenn weiterhin Blitzschlaggefahr besteht, und die Sicherheitsbedingungen der Helfer eingeschränkt sind, ist es vertretbar, mit den CPR-Maßnahmen erst nach der Rettung des Verletzten zu beginnen. In regelmäßigen Auffrischungskursen für Wiederbelebung sollte vermehrt auf wirkungsvolle Basisreanimation und primäre Blitzprävention hingewiesen werden. The mainstay of management of lightning-induced respiratory and cardiac arrest is provision of basic life support (BLS) by bystanders. Attention should focus on adequate artificial ventilation and thoracic compressions. Cardiopulmonary resuscitation (CPR) may be effective after delayed onset and even after prolonged resuscitative attempt. In case of numerous victims struck simultaneously, standard triage principles must be modified. Highest priority is given to the unconscious patient with no spontaneous breathing and circulation. When exposure to lightning is still ongoing and conditions of rescuer safety remain limited, it is acceptable to rescue the patient prior to initiation of CPR. Once spontaneous circulation is re-established, intravenous fluid therapy must be restricted. Regular CPR refresher courses should emphasize on effective bystander CPR and primary prevention of lightning casualties.
The Science and Practice of Resuscitation Medicine, 2001
The Medical journal of Australia
Resuscitation, 2004
The long-term outcome in patients who received recombinant tissue plasminogen activator during ca... more The long-term outcome in patients who received recombinant tissue plasminogen activator during cardiopulmonary resuscitation (CPR) in out-of-hospital cardiac arrest (OHCA) of non-traumatic aetiology was assessed. The neurological outcome in survivors and their level of performance, subjective well-being and quality of life were evaluated. A follow-up study of 27 cardiac arrest survivors was conducted; four patients (15%) died during the first year, a total of seven patients (26%) within 5 years. Twenty-two patients (81%) were discharged from hospital without neurological deficit (cerebral performance category (CPC) score: 1), three patients scored CPC 2 and two patients CPC 3. Heart failure classification on discharge was, according to the New York Heart Association (NYHA) criteria 2.1 +/- 0.9. Fifteen patients (56%) managed to return to their previous level of activity. At the time of follow-up 18 patients (67%) were still alive, of whom 15 responded to a survey regarding life sati...
Notfall + Rettungsmedizin, 2011
Originalien Zur Messung der Patientenzufriedenheit wurden in der Vergangenheit unterschiedliche A... more Originalien Zur Messung der Patientenzufriedenheit wurden in der Vergangenheit unterschiedliche Ansätze etabliert, die von stark subjektiven, ereignisorientierten qualitativen Messmethoden [5] bis zu mehr oder weniger standardisierten Fragebögen reichen [10, 1, 4, 14, 18]. Qualitativ hochwertige Studien verweisen auf die Wichtigkeit der Einbeziehung von Patienten und von Experten bei der Erstellung eines Fragebogens. Standardisierte Fragebögen zur Erfassung der Patientenzufriedenheit in der prähospitalen Notfallmedizin fehlen gänzlich. Bereits die Erstellung einer allgemein gültigen Definition von Zufriedenheit erweist sich als schwierig [3, 2]. Aufgrund der Komplexität des Begriffs existieren weltweit zahlreiche Definitionsvorschläge. Die Internationale Organisation für Standardisierung (ISO) definiert Zufriedenheit als den "Grad der Übereinstimmung von Anforderungen und Erwartungen (der Kunden/Patienten) und ihrer Erfüllung" [20]. Zufriedenheit ist stark subjektiv besetzt (kognitive und affektive Erfahrungswerte), hängt aber auch von sozioökonomischen, demographischen oder kulturellen Werthaltungen und Vorgaben ab [21]. Primäres Ziel dieser Studie war es, einen standardisierten, psychometrisch geprüften und validierten Fragebogen zur Evaluierung der Patientenzufriedenheit in der prähospitalen Notfallmedizin zu entwickeln und an einem ersten Notarztstützpunkt einzusetzen. Die Bewertung der Qualität der notfallmedizinischen Versorgung galt als sekundäres Ziel.
BMJ Case Reports, 2011
Air embolism (AE) is a potential complication during transthoracic needle biopsy (TNB). The autho... more Air embolism (AE) is a potential complication during transthoracic needle biopsy (TNB). The authors report on venous and systemic AE during CT-guided TNB under general anaesthesia. During the intervention, the radiologist observed accumulation of air bubbles in the left heart chambers, in the right subclavian vein, the superior vena cava and the right atrium. This was presumably due to pressure infusion of contrast medium (CM) air entrained via a stop-cock improperly fixed to the venous cannula or via the injection valve of the cannula by Venturi forces. Prevention of AE related to CM infusion is a subject for institutional risk management. Stop-cocks and injection valves should not be used in intravenous lines supplied by pressure infusions. Adverse outcome may be avoided by placing the patient head down, increasing FiO(2) to 1.0, administering antithrombotic therapy and immobilizing the patient on the intervention table until CT has proved complete remission of AE.
Resuscitation, 2004
Fractured ribs and sternum are frequent complications of thoracic compression during CPR in adult... more Fractured ribs and sternum are frequent complications of thoracic compression during CPR in adults. This study was conducted to determine whether findings of plain chest radiography (CXR) correlate with post-mortem findings in patients who underwent cardiopulmonary resuscitation (CPR) after out-of-hospital cardiac arrest. CXR findings and autopsy results of CPR-related chest injuries comprising rib and sternum fractures were compared prospectively in 19 patients. Fractures were diagnosed in nine of 19 patients by means of radiology and in 18 of 19 patients by autopsy (rib fractures in 6/19 versus 17/19, P=0.002; sternum fractures in 5/19 versus in 9/19, P=0.227. The total number of isolated bone fractures detected by CXR was 18 (12 rib and six sternum fractures) and by autopsy 92 (83 rib and nine sternum fractures). The majority of rib fractures was located in the anterior part of the thoracic cage. Sternum fractures predominantly occurred in the lower third. Eight of 19 patients received either thrombolytic or antithrombotic treatment during CPR but no major bleeding complication associated with CPR was detected by autopsy. The findings of this study indicate that fractures associated with CPR are underreported in conventional radiographic investigations. No major bleeding complications related to CPR-associated fractures was detected.
Resuscitation, 2001
Thrombolytic therapy during cardiopulmonary resuscitation (CPR) is a controversial issue in emerg... more Thrombolytic therapy during cardiopulmonary resuscitation (CPR) is a controversial issue in emergency medicine practice. This study was conducted to determine whether administration of recombinant tissue plasminogen activator (rt-PA) in out-of-hospital cardiac arrest of non-traumatic aetiology improves CPR outcome. A retrospective chart review of 401 patients with out-of-hospital cardiac arrest who were resuscitated by the emergency medical services (EMS) during a 6 year period was performed. A total of 108 patients received rt-PA during CPR and were compared to 216 controls, closely matched according to baseline characteristics, arrival status and ECG findings. Administration of rt-PA was optional. Return of spontaneous circulation (ROSC) occurred in 76 patients under rt-PA treatment (70.4 vs. 51.0% in controls; P=0.001). Fifty-two patients from the lysis group survived the first 24 h (48.1 vs. 32.9% in controls; P=0.003), while 27 (25.9%) survived to discharge. Autopsy reports revealed major bleeding complications in six patients receiving rt-PA treatment. Fulminant intracranial haemorrhage was observed in one patient who received rt-PA and in two cases from the control group. Thrombolytic therapy may improve frequency of return of spontaneous circulation substantially and increase primary survival in patients with non-traumatic cardiac arrest. Serious bleeding complications are not frequently observed under rt-PA treatment.
Medical Hypotheses, 2006
The likelihood of successful defibrillation in patients with sustained ventricular fibrillation (... more The likelihood of successful defibrillation in patients with sustained ventricular fibrillation (VF) is increased after administering thrombolytics during cardiopulmonary resuscitation (CPR). While dissolution of coronary artery thrombosis resolves the underlying cause of myocardial infarction in the majority of patients, improved microcirculatory reperfusion and alteration of the electrical activity of the fibrillation process may increase the likelihood of restoring spontaneous circulation in cardiac arrest patients. Electrocardiography is a sensitive means of displaying current myocardial perfusion in VF using changes in the frequency and amplitude of fibrillation. Our hypothesis postulates that thrombolytic therapy during CPR increases fibrillation frequency, fibrillation amplitude and amplitude spectrum area, thus improving ventricular fibrillation status and the chance of successful defibrillation.
Journal of Medical Engineering & Technology, 2010
Improved microcirculatory reperfusion in patients with ventricular fibrillation (VF) enhances the... more Improved microcirculatory reperfusion in patients with ventricular fibrillation (VF) enhances the electrical activity of the fibrillation process and increases the likelihood of successful defibrillation. Changes in amplitude spectrum area (AMSA) and mean fibrillation (MF) in patients with sustained VF were analysed after administration of rt-PA variant tenecteplase in out-of-hospital cardiac arrest (OHCA) during cardiopulmonary resuscitation (CPR). A total of 69 ECG sequences from nine patients were evaluated. Patients who received tenecteplase showed significantly longer duration of VF (p = 0.016). While AMSA declined significantly during CPR (p = 0.001), MF did not differ between groups. There were two survivors in the treatment group and one in the control group. When tenecteplase was administered during CPR, VF lasted significantly longer than in controls. Changes in MF and AMSA did not indicate improved myocardial perfusion in patients who received tenecteplase during CPR.
Journal of Medical Case Reports, 2013
Introduction: Intra-hepatic cholestasis arising from biliary strictures is a frequent complicatio... more Introduction: Intra-hepatic cholestasis arising from biliary strictures is a frequent complication in pediatric patients after liver transplantation. Minimally invasive procedures such as percutaneous drainage placement and balloon dilation are the preferred diagnostic and therapeutic modalities. Case presentation: We report the case of a 12-month-old Caucasian boy with biliary atresia who was initially treated with hepatoportoenterostomy. In the following months, he developed biliary cirrhosis, accompanied by cystic bile retention, recurrent bile duct infections and malabsorption. Six months after the initial surgical intervention, he underwent living donor liver transplantation. Within two months, the hepatico-jejunostomy became occluded leading to progressive intra-hepatic cholestasis. Under sonographic guidance, external drainage of bile was accomplished by percutaneous trans-hepatic cholangiography and drainage. In total, our patient underwent 12 interventions under general anesthesia until balloon dilatation of the hepatico-jejunostomy was successfully performed. Finally, our patient's general condition improved and he gained weight. Conclusions: Minimally invasive techniques are preferred to surgical revisions and justify even multiple attempts. Interventions under general anesthesia, though not without risks, are still reasonable. Co-operation with parents and multidisciplinary approach to complication management by the involved surgeon, radiologist, pediatrician and anesthesiologist are important.
Journal of Forensic Sciences, 2005
A bench study was performed to investigate the potential of air bubbles entering a central vein v... more A bench study was performed to investigate the potential of air bubbles entering a central vein via a central venous catheter to ascend retrograde to the brain. The results support the hypothesis that air bubbles may rise retrograde against the venous blood flow, depending on bubble size, central vein diameter and cardiac output. A review of radiological findings in published case reports indicates that the occurrence of retrograde cerebral air embolism is underestimated.
Notfall & Rettungsmedizin, 2001
Deut Med Wochenschr, 2006
Most epidemiological studies suffer from misclassification in the response and/or the covariates.... more Most epidemiological studies suffer from misclassification in the response and/or the covariates. Since ignoring misclassification induces bias on the parameter estimates, correction for such errors is important. For measurement error, the continuous analog to misclassification, a general approach for bias correction is the SIMEX (simulation extrapolation) originally suggested by . This approach has been recently extended to regression models with a possibly misclassified categorical response and/or the covariates by , and is called the MC-SIMEX approach. To assess the importance of a regressor not only its (corrected) estimate is needed, but also its standard error. For the original SIMEX approach. developed a method for estimating the asymptotic variance. Here we derive the asymptotic variance estimators for the MC-SIMEX approach, extending the methodology of . We also include the case where the misclassification probabilities are estimated by a validation study. An extensive simulation study shows the good performance of our approach. The approach is illustrated using an example in caries research including a logistic regression model, where the response and a binary covariate are possibly misclassified.
Der Anaesthesist
The number of diagnostic and surgical procedures being performed outside the core operating area ... more The number of diagnostic and surgical procedures being performed outside the core operating area is growing disproportionately. Due to the higher perioperative risk for such patients, anesthesia should only be provided by a very experienced anesthesiologist, even for supposedly small interventions. At these locations, timely and direct access to the anesthesia machine and/or the patient is often limited and if additional personnel or supplies are required, substantial time delays usually occur and should be allowed for. Standard operating procedures that are optimized to local requirements and providing a specially equipped anesthesia trolley for diagnostic and surgical procedures outside of the core operating area, may decrease the likelihood of complications induced by poorly equipped anesthesia workplaces. For electroconvulsive therapy (ECT), the standard drugs are methohexital in combination with short-acting opioids, such as remifentanil and succinylcholine. Significant variations in arterial blood pressure and heart rate are possible. Anesthesia induction in children with a known difficult airway or difficult intravascular access should initially be performed in a location with optimal infrastructure with subsequent transfer to the diagnostic or surgical suite outside the core operating area. Before entering the magnetic resonance imaging (MRI) suite, personal ferromagnetic items (e.g. pens, credit cards, stethoscopes, keys, telephones, USB sticks) should be removed to prevent injury and data loss; a MRI-compatible anesthesia machine and equipment is compulsory. Patients with cardiac pacemakers, cochlea implants, aneurysm or other clips, metallic-based tattoos or make-up are not normally compatible with MRI. General anesthesia should be preferred over conscious sedation for magnetic resonance imaging and ear protection is necessary for anesthetized patients. Gastroscopy in children should be performed under general anesthesia; and when concluding the procedure, air insufflated into the gastrointestinal tract should be suctioned in all patients. For angiography, maximum monitoring needs to be available to provide hemodynamically unstable patients with adequate anesthesia care; comprehensive radiation protection for patients and staff as well as temperature monitoring for prolonged diagnostic procedures is also necessary. Monitoring oxygen saturation and end-tidal carbon dioxide as well as employing visual and audible alarms is an essential requirement even during conscious sedation. In summary, the number of diagnostic and surgical procedures performed outside the core operating area should be reduced to a minimum and, whenever possible, diagnostic or surgical procedures should be performed within the core operating area.
Anesthesia and Analgesia, 2008
For the "Helfen Berü hrt" Study Team BACKGROUND: Many surgical interventions worldwide are perfor... more For the "Helfen Berü hrt" Study Team BACKGROUND: Many surgical interventions worldwide are performed in developing countries. To improve survival of acutely and critically ill patients in these countries, basic problems and demands of anesthesia care need to be identified. Using this survey, we evaluated the current status of anesthesia and its allied disciplines (intensive care medicine, emergency medicine, and pain therapy) in the Republic of Zambia. METHODS: Questionnaires were sent to 87 hospitals registered at the Zambian Ministry of Health as performing minor or major surgery. The questionnaire consisted of 111 questions grouped into five sections: general hospital information, anesthesia, intensive care, emergency medicine, and pain therapy. RESULTS: Sixty-eight questionnaires could be statistically evaluated (78%). The most common operations were obstetric/gynecological and abdominal surgical procedures. Dissociative ketamine anesthesia was the technique most often used for general anesthesia (50%). Endotracheal intubation was performed in 10% of patients undergoing general anesthesia. In most hospitals (78%), anesthesia was administered by nonphysicians. Only 5 of 68 hospitals (7%) reported having an intensive care unit, with 29 beds to serve the entire country. Anesthesiologists play almost no role in emergency medicine and pain therapy. CONCLUSIONS: Anesthesia in the Republic of Zambia is a highly under-developed and under-resourced medical specialty.
Notfall & Rettungsmedizin, 2002
ABSTRACT Grundpfeiler der Versorgung von blitzschlaginduziertem Atem- und Herzstillstand ist die ... more ABSTRACT Grundpfeiler der Versorgung von blitzschlaginduziertem Atem- und Herzstillstand ist die Basisreanimation durch Ersthelfer. Die Hauptaufmerksamkeit gilt der adäquaten Beatmung und Thoraxkompression. Herz-Lungen-Wiederbelebung kann auch nach verzögertem Beginn und sogar nach länger dauernden Reanimationsmaßnahmen erfolgreich sein. Wenn mehrere Personen gleichzeitig betroffen sind, müssen die Standardprinzipien der Triage modifiziert werden. Oberste Priorität erhalten bewusstlose Patienten ohne spontane Atmung und Kreislauf. Wenn weiterhin Blitzschlaggefahr besteht, und die Sicherheitsbedingungen der Helfer eingeschränkt sind, ist es vertretbar, mit den CPR-Maßnahmen erst nach der Rettung des Verletzten zu beginnen. In regelmäßigen Auffrischungskursen für Wiederbelebung sollte vermehrt auf wirkungsvolle Basisreanimation und primäre Blitzprävention hingewiesen werden. The mainstay of management of lightning-induced respiratory and cardiac arrest is provision of basic life support (BLS) by bystanders. Attention should focus on adequate artificial ventilation and thoracic compressions. Cardiopulmonary resuscitation (CPR) may be effective after delayed onset and even after prolonged resuscitative attempt. In case of numerous victims struck simultaneously, standard triage principles must be modified. Highest priority is given to the unconscious patient with no spontaneous breathing and circulation. When exposure to lightning is still ongoing and conditions of rescuer safety remain limited, it is acceptable to rescue the patient prior to initiation of CPR. Once spontaneous circulation is re-established, intravenous fluid therapy must be restricted. Regular CPR refresher courses should emphasize on effective bystander CPR and primary prevention of lightning casualties.
The Science and Practice of Resuscitation Medicine, 2001
The Medical journal of Australia
Resuscitation, 2004
The long-term outcome in patients who received recombinant tissue plasminogen activator during ca... more The long-term outcome in patients who received recombinant tissue plasminogen activator during cardiopulmonary resuscitation (CPR) in out-of-hospital cardiac arrest (OHCA) of non-traumatic aetiology was assessed. The neurological outcome in survivors and their level of performance, subjective well-being and quality of life were evaluated. A follow-up study of 27 cardiac arrest survivors was conducted; four patients (15%) died during the first year, a total of seven patients (26%) within 5 years. Twenty-two patients (81%) were discharged from hospital without neurological deficit (cerebral performance category (CPC) score: 1), three patients scored CPC 2 and two patients CPC 3. Heart failure classification on discharge was, according to the New York Heart Association (NYHA) criteria 2.1 +/- 0.9. Fifteen patients (56%) managed to return to their previous level of activity. At the time of follow-up 18 patients (67%) were still alive, of whom 15 responded to a survey regarding life sati...
Notfall + Rettungsmedizin, 2011
Originalien Zur Messung der Patientenzufriedenheit wurden in der Vergangenheit unterschiedliche A... more Originalien Zur Messung der Patientenzufriedenheit wurden in der Vergangenheit unterschiedliche Ansätze etabliert, die von stark subjektiven, ereignisorientierten qualitativen Messmethoden [5] bis zu mehr oder weniger standardisierten Fragebögen reichen [10, 1, 4, 14, 18]. Qualitativ hochwertige Studien verweisen auf die Wichtigkeit der Einbeziehung von Patienten und von Experten bei der Erstellung eines Fragebogens. Standardisierte Fragebögen zur Erfassung der Patientenzufriedenheit in der prähospitalen Notfallmedizin fehlen gänzlich. Bereits die Erstellung einer allgemein gültigen Definition von Zufriedenheit erweist sich als schwierig [3, 2]. Aufgrund der Komplexität des Begriffs existieren weltweit zahlreiche Definitionsvorschläge. Die Internationale Organisation für Standardisierung (ISO) definiert Zufriedenheit als den "Grad der Übereinstimmung von Anforderungen und Erwartungen (der Kunden/Patienten) und ihrer Erfüllung" [20]. Zufriedenheit ist stark subjektiv besetzt (kognitive und affektive Erfahrungswerte), hängt aber auch von sozioökonomischen, demographischen oder kulturellen Werthaltungen und Vorgaben ab [21]. Primäres Ziel dieser Studie war es, einen standardisierten, psychometrisch geprüften und validierten Fragebogen zur Evaluierung der Patientenzufriedenheit in der prähospitalen Notfallmedizin zu entwickeln und an einem ersten Notarztstützpunkt einzusetzen. Die Bewertung der Qualität der notfallmedizinischen Versorgung galt als sekundäres Ziel.
BMJ Case Reports, 2011
Air embolism (AE) is a potential complication during transthoracic needle biopsy (TNB). The autho... more Air embolism (AE) is a potential complication during transthoracic needle biopsy (TNB). The authors report on venous and systemic AE during CT-guided TNB under general anaesthesia. During the intervention, the radiologist observed accumulation of air bubbles in the left heart chambers, in the right subclavian vein, the superior vena cava and the right atrium. This was presumably due to pressure infusion of contrast medium (CM) air entrained via a stop-cock improperly fixed to the venous cannula or via the injection valve of the cannula by Venturi forces. Prevention of AE related to CM infusion is a subject for institutional risk management. Stop-cocks and injection valves should not be used in intravenous lines supplied by pressure infusions. Adverse outcome may be avoided by placing the patient head down, increasing FiO(2) to 1.0, administering antithrombotic therapy and immobilizing the patient on the intervention table until CT has proved complete remission of AE.
Resuscitation, 2004
Fractured ribs and sternum are frequent complications of thoracic compression during CPR in adult... more Fractured ribs and sternum are frequent complications of thoracic compression during CPR in adults. This study was conducted to determine whether findings of plain chest radiography (CXR) correlate with post-mortem findings in patients who underwent cardiopulmonary resuscitation (CPR) after out-of-hospital cardiac arrest. CXR findings and autopsy results of CPR-related chest injuries comprising rib and sternum fractures were compared prospectively in 19 patients. Fractures were diagnosed in nine of 19 patients by means of radiology and in 18 of 19 patients by autopsy (rib fractures in 6/19 versus 17/19, P=0.002; sternum fractures in 5/19 versus in 9/19, P=0.227. The total number of isolated bone fractures detected by CXR was 18 (12 rib and six sternum fractures) and by autopsy 92 (83 rib and nine sternum fractures). The majority of rib fractures was located in the anterior part of the thoracic cage. Sternum fractures predominantly occurred in the lower third. Eight of 19 patients received either thrombolytic or antithrombotic treatment during CPR but no major bleeding complication associated with CPR was detected by autopsy. The findings of this study indicate that fractures associated with CPR are underreported in conventional radiographic investigations. No major bleeding complications related to CPR-associated fractures was detected.
Resuscitation, 2001
Thrombolytic therapy during cardiopulmonary resuscitation (CPR) is a controversial issue in emerg... more Thrombolytic therapy during cardiopulmonary resuscitation (CPR) is a controversial issue in emergency medicine practice. This study was conducted to determine whether administration of recombinant tissue plasminogen activator (rt-PA) in out-of-hospital cardiac arrest of non-traumatic aetiology improves CPR outcome. A retrospective chart review of 401 patients with out-of-hospital cardiac arrest who were resuscitated by the emergency medical services (EMS) during a 6 year period was performed. A total of 108 patients received rt-PA during CPR and were compared to 216 controls, closely matched according to baseline characteristics, arrival status and ECG findings. Administration of rt-PA was optional. Return of spontaneous circulation (ROSC) occurred in 76 patients under rt-PA treatment (70.4 vs. 51.0% in controls; P=0.001). Fifty-two patients from the lysis group survived the first 24 h (48.1 vs. 32.9% in controls; P=0.003), while 27 (25.9%) survived to discharge. Autopsy reports revealed major bleeding complications in six patients receiving rt-PA treatment. Fulminant intracranial haemorrhage was observed in one patient who received rt-PA and in two cases from the control group. Thrombolytic therapy may improve frequency of return of spontaneous circulation substantially and increase primary survival in patients with non-traumatic cardiac arrest. Serious bleeding complications are not frequently observed under rt-PA treatment.
Medical Hypotheses, 2006
The likelihood of successful defibrillation in patients with sustained ventricular fibrillation (... more The likelihood of successful defibrillation in patients with sustained ventricular fibrillation (VF) is increased after administering thrombolytics during cardiopulmonary resuscitation (CPR). While dissolution of coronary artery thrombosis resolves the underlying cause of myocardial infarction in the majority of patients, improved microcirculatory reperfusion and alteration of the electrical activity of the fibrillation process may increase the likelihood of restoring spontaneous circulation in cardiac arrest patients. Electrocardiography is a sensitive means of displaying current myocardial perfusion in VF using changes in the frequency and amplitude of fibrillation. Our hypothesis postulates that thrombolytic therapy during CPR increases fibrillation frequency, fibrillation amplitude and amplitude spectrum area, thus improving ventricular fibrillation status and the chance of successful defibrillation.
Journal of Medical Engineering & Technology, 2010
Improved microcirculatory reperfusion in patients with ventricular fibrillation (VF) enhances the... more Improved microcirculatory reperfusion in patients with ventricular fibrillation (VF) enhances the electrical activity of the fibrillation process and increases the likelihood of successful defibrillation. Changes in amplitude spectrum area (AMSA) and mean fibrillation (MF) in patients with sustained VF were analysed after administration of rt-PA variant tenecteplase in out-of-hospital cardiac arrest (OHCA) during cardiopulmonary resuscitation (CPR). A total of 69 ECG sequences from nine patients were evaluated. Patients who received tenecteplase showed significantly longer duration of VF (p = 0.016). While AMSA declined significantly during CPR (p = 0.001), MF did not differ between groups. There were two survivors in the treatment group and one in the control group. When tenecteplase was administered during CPR, VF lasted significantly longer than in controls. Changes in MF and AMSA did not indicate improved myocardial perfusion in patients who received tenecteplase during CPR.
Journal of Medical Case Reports, 2013
Introduction: Intra-hepatic cholestasis arising from biliary strictures is a frequent complicatio... more Introduction: Intra-hepatic cholestasis arising from biliary strictures is a frequent complication in pediatric patients after liver transplantation. Minimally invasive procedures such as percutaneous drainage placement and balloon dilation are the preferred diagnostic and therapeutic modalities. Case presentation: We report the case of a 12-month-old Caucasian boy with biliary atresia who was initially treated with hepatoportoenterostomy. In the following months, he developed biliary cirrhosis, accompanied by cystic bile retention, recurrent bile duct infections and malabsorption. Six months after the initial surgical intervention, he underwent living donor liver transplantation. Within two months, the hepatico-jejunostomy became occluded leading to progressive intra-hepatic cholestasis. Under sonographic guidance, external drainage of bile was accomplished by percutaneous trans-hepatic cholangiography and drainage. In total, our patient underwent 12 interventions under general anesthesia until balloon dilatation of the hepatico-jejunostomy was successfully performed. Finally, our patient's general condition improved and he gained weight. Conclusions: Minimally invasive techniques are preferred to surgical revisions and justify even multiple attempts. Interventions under general anesthesia, though not without risks, are still reasonable. Co-operation with parents and multidisciplinary approach to complication management by the involved surgeon, radiologist, pediatrician and anesthesiologist are important.
Journal of Forensic Sciences, 2005
A bench study was performed to investigate the potential of air bubbles entering a central vein v... more A bench study was performed to investigate the potential of air bubbles entering a central vein via a central venous catheter to ascend retrograde to the brain. The results support the hypothesis that air bubbles may rise retrograde against the venous blood flow, depending on bubble size, central vein diameter and cardiac output. A review of radiological findings in published case reports indicates that the occurrence of retrograde cerebral air embolism is underestimated.