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W Panzer

Publications and source records attributed to W Panzer.

At least 37 records · Page 2Linked to original sources
PubMed1998

Calculation of backscatter factors for diagnostic radiology using Monte Carlo methods.

Backscatter factors were determined for x-ray beams relevant to diagnostic radiology using Monte Carlo methods. The phantom size considered most suitable for calibration of dosimeters is a cuboid of 30 x 30 cm2 front surface and 15 cm depth. This phantom size also provides a good approximation to adult patients. Three different media were studied: water, PMMA and ICRU tissue; the source geometry was a point source with varying field size and source-to-phantom distance. The variations of the backscatter factor with phantom medium and field geometry were examined. From the obtained data, a set of backscatter factors was selected and proposed for adoption as a standard set for the calibration of dosimeters to be used to measure diagnostic reference doses.

Adult↗
PubMed1997

The decision to terminate resuscitative efforts: results of a questionnaire.

Despite all the progress made in emergency medicine, out-of-hospital resuscitative efforts still remain unsuccessful in the majority of cases and a decision concerning termination of cardiopulmonary resuscitation (CPR) has to be made. We used a multi-question survey to assess the attitude of emergency physicians towards the duration of an unsuccessful resuscitation attempt in non-traumatic cardiac arrest, and to identify the criteria affecting the decision to terminate CPR in the prehospital setting. More than 400 physicians participated in the inquiry on CPR in adults. If spontaneous circulation cannot be restored, the majority (65%) abandon the resuscitation attempt at the latest after performing advanced cardiac life support for 45 min. The participants indicated the following factors as criteria for the termination of unsuccessful CPR: pre-existing diseases (92%), presumed interval between onset of arrest and application of CPR (92%), duration of the resuscitation attempt (90%), age of the patient (89%), electrocardiographic (ECG) alterations such as persistent asystole/ventricular fibrillation or electromechanical dissociation (83%), persistent fixed and dilated pupils (78%), lack of brain stem reflexes (31%), body temperature (12%) and suspected drug intoxication (8%). The answers reflect the physicians opinions on termination of CPR even if they do not present real decisions under emergency conditions. The results indicate that in addition to the failure to restore spontaneous circulation, other factors are involved in decision making at the scene. A high rate of respondents include criteria of weak diagnostic value such as the pupillary status, or factors of doubtful prognostic significance such as the patient's age. Concerning the patient's history and underlying diseases, the emergency physician often has to resort to presumptions. We conclude that the decision to terminate CPR is made by most physicians considering the specific circumstances of the cardiac arrest.

Adult↗
PubMed1997

Skills of lay people in checking the carotid pulse.

American Heart Association as well as European Resuscitation Council require the carotid pulse check to determine pulselessness in an unconscious victim and to decide whether or not cardiopulmonary resuscitation (CPR) should be initiated. Recent studies on the ability of health professionals to check the carotid pulse have called this diagnostic tool in question and led to discussions. To contribute to this discussion we performed a study to evaluate skills of lay people in checking the carotid pulse. A group of 449 volunteers (most had participated in a first aid course) were asked to check the carotid pulse in a young healthy, non-obese person by counting aloud the detected pulse rate. Time intervals until correct detection of the carotid pulse were registered. Overall the volunteers needed an average of 9.46 s, ranging from 1 to 70 s. Only 47.4% of the volunteers were able to detect a pulse within 5 s, and 73.7% within 10 s. A level of 95% volunteers detecting the pulse correctly was reached only after 35 s. Based on these findings we conclude that the intervals established for carotid pulse check may be too short and that perhaps the value of pulse check within in the scope of CPR needs to be reconsidered.

Adult↗
PubMed1997

[Exitus letalis caused by liquid nitrogen].

A 24-year old student died from asphyxiation while filling flasks with liquid nitrogen. The upper and lower extremities and the back were frozen. The face, ears and neck were livid with a horizontal line of demarcation. A few wide ventricular complexes were seen in the initial ECG, followed by asystole. The patient's trachea was intubated, his lungs ventilated with 100% oxygen and CPR initiated. The site of larynx and pharynx were without pathological findings. 250 ml of a crystalloid solution were infused into the external jugular vein. It was not possible to measure the body temperature. Venous blood gas analysis showed a metabolic acidosis and hyperkaliaemia. CPR was terminated after 90 minutes. Own protection is most important for the rescue team if a nitrogen atmosphere is expected.

Adult↗
PubMed1996

Influence of different types of recovery positions on perfusion indices of the forearm.

BACKGROUND: Basic life support guidelines of the European Resuscitation Council (ERC) suggest a modified type of recovery position compared to that recommended by the American Heart Association (AHA). However, anecdotal reports and the results of a small study by Fulstow and Smith (Resuscitation 1993; 26: 89-91) gave evidence that the new ERC position may cause an impairment of perfusion of the lower forearm. The aim of our study was to evaluate the effects of different recovery positions on arterial perfusion and venous drainage of the forearm. METHODS: We placed 20 young healthy volunteers randomly in either ERC or AHA position for 15 min first, and in the other position thereafter. Before and between volunteers were positioned supine. In a second series 10 volunteers were positioned according to the same protocol in semiprone positions as described by Morrison, Mirkhur and Craig (MMC), and Rautek's position, respectively. Forearm perfusion indices of the dependent arm were continuously assessed by photoplethysmographic pulsatility change, photoplethysmographic volume change, invasive peripheral venous pressure and non-invasive blood pressure amplitude. Subjective discomfort was assessed non-qualitatively. RESULTS: All indices of arterial perfusion demonstrated an impairment of arterial inflow in ERC, MMC and Rautek's position as well as venous congestion in these three positions. On the contrary, AHA position was associated with no significant changes of arterial flow and only moderate, insignificant signs of venous congestion. CONCLUSION: The results of this study suggest that AHA position causes less circulatory disturbances than the ERC, MMC and Rautek's positions.

Adult↗
PubMed1996

ACD versus standard CPR in a prehospital setting.

BACKGROUND: Animal and human studies in cardiac arrest demonstrate significant improvements in systolic blood pressure, coronary perfusion pressure and total brain and myocardial blood flow with active compression-decompression (ACD) cardiopulmonary resuscitation (CPR). The results of recent studies in patients with out-of-hospital cardiac arrest and use of ACD-CPR are non-uniform and require supplementation. METHODS: In a retrospective non-randomised design, 152 adult patients with prehospital cardiac arrest, not caused by trauma or hypothermia, were studied. Compressions were performed according to the recommendations of the American Heart Association. Three ACD devices were assigned to seven rescue units changing monthly. Study end-points were the rates of return of spontaneous circulation (ROSC), admission to hospital, survival at 24h, hospital discharge and neurologic outcome. RESULTS: 70 (46%) patients underwent standard (STD) CPR and 82 (54%) patients were treated with ACD-CPR. Both groups were comparable with regard to age, sex, witnessed cardiac arrests, bystander CPR, cause of arrest, time intervals, number of defibrillations, and total amount of epinephrine. No significant differences in outcome could be found: 20 patients (29%) who received STD-CPR, and 14 patients (17%) who underwent ACD-CPR survived to hospital discharge. Neither at other end-points nor in any subgroups could any significant differences be discovered. Patients regaining ROSC showed a significant difference in favour of STD-CPR for the end-points of hospital admission, 24-h survival and hospital discharge. CONCLUSION: No significant differences in hospital discharge and neurological outcome were found between STD-CPR and ACD-CPR.

Adult↗
PubMed1996

[Radiation exposure in interventional radiology as exemplified by the chemoembolization of hepatocellular carcinoma and laser angioplasty of the pelvic arteries].

PURPOSE: Estimation of radiogenic risks for patient and radiologist in chemoembolisation of hepatocellular carcinoma (HCC) and laser angioplasty of the pelvic arteries. METHODS: In 5 chemoembolisations of HCC (4 males, one female) and 6 laser angioplasties of the pelvic arteries (5 males, one female) the surface doses received by patient and operator were measured using thermoluminescent dosimeters in standardised positions. The organ doses of the patient were derived by conversion factors employed on the measured surface doses. Effective dose was determined according to the recommendations of ICRP 60. RESULTS: The risk of lethal malignant disease and genetic disorder derived from the doses in the patient was found to be of the magnitude of 10(-4)-10(-5). The thresholds for transient erythema of the skin and depression of hematopoiesis can be reached after high expositions. A theoretical maximum of 700 laser angioplasties of the pelvic arteries allowable in one year was calculated based on the dose to the operator's left hand. For chemoembolisation of HCC, the dose to the left eye lens would reach the yearly maximum after approximately 1000 procedures. Remarkable risks for malignant disease of skin and thyroid as well as detectable opacities of the eye lens can occur after frequent interventions for many years. CONCLUSIONS: Because of the lower life expectancy the patient's risk for stochastic effect can be seen as minimal. No clinically relevant deterministic effects will occur. In the case of frequent interventions, the dose absorbed by the radiologist is likely to exceed the prescribed dose limit and to cause remarkable risk for stochastic and non-stochastic effects after many years.

Aged↗
PubMed1993

Effective dose--how effective for patients?

The question discussed in this paper is whether effective dose can reflect the risk to patients from radiological procedures and can be used, for example, to optimise procedures and compare risks of various methods, to define dose constraints, and to estimate the risks to individuals or populations attributed to medical exposures. This report demonstrates that the use of effective dose for patients could be misleading or even wrong due to inappropriate simplifications of the underlying biological mechanisms and inappropriateness of the weighting factors connected with the definition of effective dose for a given patient population. We show that the choice of the most meaningful quantities to express patient exposure depends strongly on the respective situation.

Bone Marrow↗
PubMed1988

[A field study to determine dosages in computed tomography].

122 CT scanners were studied in order to determine close values free in air on the axis of rotation during the most common types of examination. In addition, other exposure parameters were collected, which may be important in relation to dose to patients. The results showed a surprising variation in the dose values of CT examinations. It is concluded that it is not possible to estimate patient exposure reliably by using the information on exposure parameters supplied by the operator.

Humans↗
PubMed1986

[Analysis of 35,013 gynecologic laparoscopies (East German survey). 1].

Statistic from 81 women hospitals in which a total of 35,013 laparoscopies had been made figures were collected by means of questionnaires (inquiry forms). The largest increase of laparoscopies (56.2%) could be found since 1980. Results showed that in 48 hospitals (59.3%) less than 50 laparoscopies were made per year. In all hospitals laparoscopy was performed under clinical conditions by the gynaecologist, mainly using endotracheal anesthesia (96.3%). 20 hospitals (24.7%) are able to perform laparoscopies in the day-time only. More than 90% of the questioned ones regarded thoracic roentgenogram, electrocardiogram as well as urine examination and hemoglobin determination as sufficient pre-examinations. 70.4% of the questioned hospitals demand a written confirmation that before the operation was carried out appropriate instructions had been given. The technical performance of laparoscopy corresponds to today's usual practice. For the pneumoperitoneum, for which 51.8% of the hospitals use an automatic system, CO2 (6.7%) is preferred. Patients are dismissed from hospital on 1st (19.8%), 2nd (50.6%) or 3rd day after the operation and later in 29.5% of the cases. Women are unable to work for an average of eight days following laparoscopy.

Diagnostic Tests, Routine↗
PubMed1986

[Analysis of 35,013 gynecologic laparoscopies (East German survey). 2].

In 81 women's hospital, in which 35,013 gynaecological laparoscopies were made, 42.9% of the specialists are able to perform laparoscopies by themselves. 51.9% of the questioned hospital directors recommend learning how to perform laparoscopies during specialization, and 48.1% plead for laparoscopy training only for gynaecologic specialists. 64.2% of the questioned ones were in favour of laparoscopy courses. Performance of diagnostic laparoscopies was recommended for all gynaecological institutions by 82.7%. In the opinion of the majority (74.8%) operative laparoscopies should be done only in larger central hospitals. It was generally agreed that chronic diseases of the lower abdomen, sterility and suspected ectopic pregnancy are indications for laparoscopy. Other acute complaints have been diagnosed less frequently by means of laparoscopy. Second-look-laparoscopies were made by 59.3% and 55.6% of the questioned doctors, mainly for checking the situation operations because of ovarian cancer and sterility. In 61.1% of all hospitals other diagnostic and therapeutic operations per laparoscopiam are done. The rate of severe complications was 0.21%, and the mortality rate amounted to 0.057%.

Curriculum↗
PubMed1983

Slot technique--an alternative method of scatter reduction in radiography.

The most common method of scatter reduction is the use of an antiscatter grid. Its disadvantage is the absorption of a certain percentage of primary radiation in the lead strips of the grid and the fact that due to the limited thickness of the lead strips their scatter absorption is also limited. A possibility for avoiding this disadvantage is offered by the so-called slot technique, ie, the successive exposure of the subject with a narrow fan beam provided by slots in rather thick lead plates. In this paper the results of a comparison between grid and slot technique regarding dose to the patient, scatter reduction, image quality and the effect of automatic exposure control are reported.

Radiation Dosage↗
PubMed1979

Stripping of X-ray bremsstrahlung spectra up to 300 kVp on a desk type computer.

The direct result of a spectrometric measurement is a pulse height distribution. In the energy region up to 300 keV three corrections in particular need to be applied to get the photon spectrum: corrections for K-escape, Compton scattering and inefficient photon absorption. A simple 'stripping' procedure is described which may be implemented on a desk type computer. All data necessary are either available in the literature or may be derived from the measurement of very heavily filtered X-ray spectra. The accuracy of the procedure is better than +/- 5% of the peak value. Results are compared with a more detailed stripping procedure, based on Monte Carlo calculated data.

Computers↗