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Biomedical subjects

M Baum

Publications and source records attributed to M Baum.

At least 487 records · Page 27Linked to original sources
PubMed1976

Evaluation of radiography and isotopic scintigraphy for detecting skeletal metastases in breast cancer.

Experience with technetium-phosphate compounds for skeletal scintigraphy in patients with breast cancer was analysed. When tumours were 5 cm or less in diameter (T1-2N0-1M0) metastases were demonstrated by radiographs in 1-7% (2/114). However, when radiography did not demonstrate metastases, lesions were found by scintigraphy in 41-3% (19/46). When lesions demonstrated by scintigraphy at the same site as abnormalities regarded as "benign" by radiography were excluded, 23% (11/46) had scintigraphs strongly suggestive of metastases. It is proposed that routine radiographic skeletal survey for patients presenting with breast cancer be abandoned, and replaced by skeletal scintigraphy, chest radiography, and specific localised radiographs of lesions demonstrated by scintigraphy. It is suggested that with this policy the development of expertise in interpreting scintigraphs will be accelerated, the cost of pre-treatment assessment will be reduced, and clinical management rationalised.

Bone Neoplasms↗
PubMed1976

The final examination in United Kingdom medical schools, 1974.

The structure, character and results of the final M.B. examinations held in United Kingdom medical schools in 1974 were investigated by postal questionnaire. The mean failure rate (10-5%, range 0-24-6%) was significantly higher in the student sample from the London medical schools compared with those in the periphery. No significant sex difference in total failure rate was noted. Wide variations were observed in the length and character of the examinations.

Education, Medical, Undergraduate↗
PubMed1976

Surface properties of amniotic fluid and fetal lung maturity.

Surface activity of 75 amniotic fluid samples from pregnancies which ended before term or at term with small-for-date newborns was measured in the surface balance. The results were correlated with the clinical symptomatology and the birth weight of the newborn. The surface properties of the lungs of those infants who had died were assessed by the buble stability method (Pattle), by recording of pressure-volume diagram and by measurements of surface activity of lung extracts. The results indicate that gamma-min is the essential parameter in determining the degree of fetal lung maturity. In cases with gamma-min values of amniotic fluid above 27 dyn/cm, a 100% respiratory distress syndrome (RDS) incidence is to be expected; values between 23 and 27 dyn/cm have a 70% values between 17 and 23 dyn/cm have a 30% incidence of RDS and in all cases with values below 17 dyn/cm, RDS may be rules out. When induced delivery before term is considered, this method of determining the degree of fetal lung maturity is, therefore, of significant prognostic reliability.

Amniotic Fluid↗
PubMed1976

Prediction of human spleen size by computer analysis of splenic scintigrams.

A method of assessing spleen size from splenic scintigraphs obtained using autologous heat damaged 99Tcm labelled red cells is described. The method depends on a "computed volume" estimate. The method has a correlation coefficient of 989 with the exsanguinated weight ofthe spleen after splenectomy and has been shown to have an accuracysuperior to methods previously described.

Computers↗
PubMed1976

A fluidic-controlled, miniature respirator with a new positive airway pressure device.

A simple and miniature respirator was developed providing controlled ventilation and application of a positive airway pressure. The positive airway pressure is achieved by an airflow through a canula into the airways. During expiration the direction of this insufflated air-flow is changed and the dynamic pressure necessary for it manifests itself as a positive airway pressure. Mechanical ventilation functions according to the principle of the Ayre-T-Piece: flow direction and, therefore ventilation, is controlled by occlusion of the expiratory limb. Occlusion is brought about by inflating a balloon. The inflation of the balloon is controlled by fluidic-circuits. They allow setting of frequency, duration of inspiration and pressure limit. As the above mentioned system for creating a positive airway pressure is integrated, mechanical ventilation with PEEP is achieved. Tests on a lung model were performed to establish the variables which influence the amount of positive pressure produced by an air-flow through a canula into a tube. Results indicate that the positive pressure obtained is inversely correlated to the diameter of tube and canula and varies with the angle of inflow (Tab. I, II, Fig. 4). The pressure-rise-velocity depicted in Fig. 5 suggests that sighing is possible in an open system. On an anencephalic newborn pressure-flow-ratios were established (Fig. 6). Pressure-time curves during spontaneous breathing, CPAP assisted breathing and sighing combined with CPAP were recorded in a 3 month old baby (Fig. 7, 8, 9). The discussion states the technical performance of the respirator (frequency 100/min-1/3 min., tidal volume 5-100 ml, controlled ventilation with pressure limitation, application of PEEP) and additional advantages (no apparatus deadspace, disposable i.e. sterile air supply-system, the miniature dimensions 10 x 10 x 5 cm, versatility and simple therefore technically reliable construction).

Humans↗
PubMed1976

The influence of the internal compliance of a respirator on the alveolar gas distribution.

The occurrence of intrapulmonary redistribution "pendelluft" during the plateau phase of a respirator, with and without internal compliance, was studied in a lung-model which simulated an obstructive inhomogeneity. Internal compliance was achieved by adding a flask, with a variable volume, to the patient circuit of a respirator which had a low compressible volume (Engström Care System ECS 2000, Junger Instrument AB, Sweden). The amount of redistributed volume was found to be dependent upon the internal compliance. Without additional compressible volume, the ventilator produced up to 18% redistribution which under all conditions could be brought below the 1% level when an internal compliance was introduced. A highly significant correlation between the amount of redistributed volume (pendelluft) and the discharge time-constant of the plateau (taupl = CI (RI + Rtr) could be established. The results of mathematical consideration gained from an electrical analogue coincided with our experimental findings. From this, some consequences could be derived for the design of an internal compliance for use with a respirator.

Airway Obstruction↗
PubMed1976

[Direct measurement of papillary muscle dynamics in the intact canine left ventricle during acute coronary occlusion (author's transl)].

UNLABELLED: The functions of the normal and ischemic papillary muscle in the intact canine heart were studied using an ultrasonic transit time method. Miniaturized piezoelectric crystals (1.5-2 mm 0) were implanted during extracorporeal circulation into the root and tip of the anterior and posterior papillary muscle of the left ventricle. RESULTS: 1. Phasic changes of left ventricular geometry during the heart cycle determine the dynamic pattern of papillary muscle movements. 2. The amplitude and velocity of papillary muscle length is directly related to those of myocardial wall segments. 3. Experimental ischemia induces total dysfunction of the papillary muscle within seconds. 4. Despite total muscle dysfunction no mitral insufficiency occured.

Animals↗
PubMed1975

Physical aspects of automatic respirators.

Objective of artificial ventilation is to maintain sufficient gas exchange with the lowest degree of mechanical burden to the lung that is possible. The basic principle of IPPV is a pressure gradient between the upper airways and the alveoli during inspiration, thus creating a positive gas flow to the lungs. Different technical arrangements can be chosen to overcome the resistances of the lung, depending upon whether the flow or the pressure is the underlying parameter for artificial ventilation. The driving system can be either compressed gas from a pipeline or an electrically driven pump or compressor. With the direct acting generator, the force of the driving mechanism directly inflates the lung, whereas the indirect acting generator has flexible coupling element between pump and patient. The switchover from inspiration to expiration is determined by the cycling parameter, uhich can either be the pressure, the flow, the volume or the time. The mode of cycling influences the reaction of the respirator to changing lung conditions. Only the volume and time cycled types maintain a constant ventilation volume with changing lung resistances. Lastly, the different behavior of respirators during expiration is discussed. An active support of expiration by means of a negative pressure has less meaning nowadays. On the other hand, a positive end expiratory pressure (PEEP) has turned out to be a very helpful tool in long-term ventilation.

Airway Resistance↗