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Biomedical subjects

G Wolff

Publications and source records attributed to G Wolff.

At least 145 records · Page 8Linked to original sources
PubMed1985

[Relation between intraoperative blood flow measurements and graft patency afer aortocoronary bypass surgery].

During aorto-coronary bypass surgery, electromagnetic flow measurements of venous grafts were performed in 50 consecutive patients at rest and after stimulation with papaverine (2 mg) to assess whether early postoperative patency was predictable. The overall patency rate at day 9-11 was 95.4% (145/152 distal grafts; 118 proximal grafts). Flow in all bypass grafts averaged 52.5 +/- 31.4 ml/min and increased after papaverine stimulation by 46.9 +/- 32.2 ml/min (p less than 0.01). 5 of 6 grafts with a flow of less than 30 ml/min and without adequate flow increase after papaverine (less than 80%) were occluded. Grafts with a flow of greater than or equal to 30 ml/min or an increase of greater than or equal to 80% after papaverine, had a high short-time patency rate (98%). Thus, perioperative flow measurements combined with papaverine stimulation predicted early patency of single grafts with an accuracy of 95%.

Coronary Artery Bypass↗
PubMed1985

A new X-linked syndrome with muscle atrophy, congenital contractures, and oculomotor apraxia.

Six men from three generations of one family had manifestations of a possible new syndrome. All had congenital contractures of the feet at birth, a slowly progressive predominantly distal muscle atrophy, dyspraxia of the eye, face, and tongue muscles, and mild mental retardation. The pedigree is compatible with X-linked recessive inheritance with no detectable manifestations in the obligate carriers. Linkage analysis excludes close linkage with the Xg locus and a polymorphic DNA sequence from the long arm of the X chromosome (DXS17).

Adolescent↗
PubMed1985

Reliable detection of inspiration and expiration by computer.

A new computer assisted method is proposed to distinguish between the inspiratory and expiratory phases of breathing. The method is based on the analysis of both gas flow and CO2-concentration. The algorithm is effective and reliable and is most suitable in critical care patients when an uninterrupted sequence of breaths is to be analysed immediately at the bedside. Marked variations in tidal volume such as are seen in intermittent mandatory ventilation or spontaneous breathing during the phase of weaning from the ventilator, artefacts such as mechanical vibrations of the flow transducer or its connecting tubes do not disturb the analysis.

Computers↗
PubMed1985

A simple method for estimating compliance.

In intensive care medicine, pulmonary compliance is one of the very helpful diagnostic indices. Because of technical difficulties, however, the measurement of pulmonary compliance is often reduced to a rough guess of the compliance of the total respiratory system. The technical problems can be overcome using a computer to solve the basic equations with the least-squares fit (LSF) method. Unfortunately, this method requires such a long calculation time that bedside breath-by-breath calculations are impracticable on small computers. A simple computer algorithm (mean-values method) was therefore developed and compared to the LSF method. Compliance values calculated by either procedure were practically identical in ventilated patients. However, by reducing computing time to 30% of the LSF method, our mean-values algorithm enabled real-time estimation of compliance breath-by-breath.

Humans↗
PubMed1985

Accurate measurement of N2 volumes during N2 washout requires dynamic adjustment of delay time.

Measurement of respiratory gas composition by a mass spectrometer lags behind the measurement of gas flow. To obtain specific gas volumes (e.g., the N2 volume) by multiplication and integration of concentration and flow, one has to synchronize flow and concentration signals using the delay time (TD) of the gas analyzer. During the N2 washout, however, gas composition changes and causes alterations of TD. This leads to errors of up to 17 and 70% in the measurement of pulmonary volume and series dead space, respectively, in an ideally mixing physical model of the lung. On the basis of Poiseuille's law and exact measurements of the characteristics of the capillary it is possible to adjust the synchronization, which improves the absolute accuracy considerably.

Animals↗
PubMed1985

[Parental guilt experience in diseases of their children].

Parents of sick or handicapped children often exhibit strong guilt feelings. These can be justified but equally can be irrational, based on magic, prescientific thinking. However, quite often they have an emotionally stabilising function for the parents. Using clinical examples possible reasons for, and the importance of these parental guilt feelings in coping with the disease are analysed. Suggestions for dealing with these guilt feelings in a differentiated manner are formulated.

Anger↗
PubMed1984

Series dead space volume assessed as the mean value of a distribution function.

Series dead space (VdS) is assumed to be represented by that volume exhaled until alveolar gas is observed. Phase II of the single breath CO2-diagram contains the (flow, concentration and sequence weighted) distribution off all stationary interfaces (SI) expired before phase III. We describe a new method to estimate the mean value of VdS based on the differentiation of phase II. This approximation of VdS is called the 'Pre Interface Expirate' (PIE) and is compared in this study with the integrative approach of Langley. Tidal volume (Vt) and PEEP were varied from 71 to 123% and from 0 to 6 cmH2O respectively. The estimation of VdS by differentiation of phase II (PIE) shows excellent reproducibility and depends only on phase II - not on phase III and IV as does VdS-Langley. PIE does not depend on Vt and PEEP per se but reflects the distension of convective airways due to elevated end-inspiratory airway pressure. Our results confirm the predictions of Paiva's model calculations in that the size of VdS is determined by the distension of airways rather than by the altered position of the SI.

Computers↗
PubMed1984

Virilization without adrenal hyperplasia in 21-hydroxylase deficiency during fetal life.

The characteristic excess production of androgens in the cortisol 21-hydroxylase defect is generally considered to be secondary to ACTH stimulation of alternate pathways. Whenever a morphological examination of the adrenals has been possible in this disorder, adrenocortical hyperplasia was a constant finding. The availability of methods for the prenatal diagnosis of the 21-hydroxylase defect has made it possible to examine some of the manifestations of this disorder during fetal life. We studied a severely virilized 20-week-old aborted female fetus with the 21-hydroxylase defect whose adrenals were neither grossly enlarged nor microscopically hyperplastic. In a pregnancy at risk for congenital adrenal hyperplasia due to a 21-hydroxylase deficiency, amniocentesis was performed in the 18th week of gestation. The 21-hydroxylase defect was established by HLA typing and highly elevated levels of 17-hydroxyprogesterone, testosterone, and androstendione in amniotic fluid. After counselling, the parents, who already had a girl with the salt-wasting form of 21-hydroxylase deficiency, wished termination of the pregnancy. The aborted 20-week-old fetus was within the normal range for gestational age in weight and height. The external genitalia were ambiguous and extremely virilized, with an enlarged clitoris and fused labioscrotal folds. A urogenital sinus opened at the base of the clitoris. The internal organs were female, with a normal uterus and ovaries. Both adrenals were normal in size and weight for their gestational age. Histological examination of the adrenals revealed no abnormalities, and no hyperplasia was detectable. Thus, the adrenals in the 21-hydroxylase defect during fetal life secrete excessive amounts of androgens and cause virilization in the absence of adrenocortical hyperplasia.

Adrenal Hyperplasia, Congenital↗
PubMed1984

[Incidence of chronic gastritis in foreign patients with chronic dyspepsia].

In 55 Patients with non-ulcer dyspepsia from Non-European countries gastric mucosa from antrum and corpus was examined (by taking at least two specimens, at least one of them includes muscularis mucosae). For comparison we took 87 patients from European countries (incl. GDR). With regard to the gastritis of antrum we observed no differences. On the other hand in corpus we found a normal mucosa more often among patients from Non-European countries, especially from Asia and Africa and in age group 40-49 years. Presumably in these patients chronic gastritis comes in older age.

Adult↗
PubMed1983

[The impossibility of direct flow measurements in lung function studies. Analysis of errors and compensation].

The authors demonstrate that the conditions for correct flow measurement are not fulfilled when a resistive flow transducer (Fleisch pneumotachograph, screen pneumotachograph etc.) is connected directly to the mouth or to the end of the endotracheal tube. This is because the composition, temperature and water content of the respiratory gas varies markedly within a respiratory cycle, the mechanically ventilated patient exhales with a huge expiratory initial peak flow, and laminar flow tends to switch over to turbulent flow in this system. Methods are proposed of continuously compensating the effects of changing gas composition, reducing expiratory peak flow without an increase in expiratory resistance, and preventing the occurrence of turbulent flow. The improvement of measuring accuracy to 2% makes the estimation of respiratory volumes more reliable. Secondly, the increased quality of primary data enables one to analyze these data in a more complex and sophisticated manner (N2-washout compartment analyses, VDS, investigation of complicated modes of ventilation such as IMV, etc.).

Humans↗
PubMed1983

[Behavior of functional residual capacity in acute respiratory insufficiency].

Variations of functional residual capacity (FRC, estimated by the N2-washout technique) and oxygenation (PaO2/FIO2) were investigated in patients mechanically ventilated for acute respiratory failure (ARF, caused by pneumonia). The various ventilatory modes were compared. The results were as follows: 1. If FRC is reduced due to ARF, the reduction is diminished by PEEP. The quantitative amount of this effect cannot be predicted in the individual patients. 2. If CPPV is switched to IMV or CPAP with an equal PEEP value, FRC was not usually changed when the clinical course was favourable; however, FRC decreased if clinical signs of insufficient spontaneous respiration were present. The proportion of FRC reduction following such a change of respiratory mode was equal to the effect of removal of PEEP from 10 cm H2O to zero. 3. FRC and oxygenation do not undergo a parallel change in every situation. 4. Treatment and further research should focus not only on increasing reduced lung volume but mainly on diverting ventilation to perfused lung regions.

Acute Disease↗
PubMed1983

Direct accurate gas flow measurement in the patient: compensation for unavoidable error.

It is shown that the conditions for accurate flow measurement are not met if the resistant flow meter (e.g., Fleisch pneumotachograph or screen pneumotachograph) is attached directly at the mouth or endotracheal tube and the breath flows directly through it, firstly because its gas composition, temperature, and humidity change radically even within the course of one respiratory cycle, secondly because the expiratory peak flow of the patient being ventilated rapidly tends to become too high, and thirdly because the entire system is sensitive to turbulence. Methods are proposed to compensate continuously for the influence of the changing gas concentrations and to reduce expiratory peak flow without increasing resistance. With the resulting reduction in the error from 20% to about 2%, tidal volume can be more reliably determined, and the higher quality of primary data allows a more differentiated and more complex evaluation (N2-washout compartment analysis, VDS measurement, analysis of complicated patterns of spontaneous breathing or mechanical ventilation such as IMV, etc.).

Humans↗